HEST
Operation Manual
for
HWJT-09C Microcomputer
Excitation Equipment
WUHAN HONGSHAN ELECTRICAL SCIENCE& TECHNOLOGY CO., LTD.
HEST
Operation Manual for HWJT-09C Micro-computer Excitation Regulator
1、 Modification records
Document name: Operation manual for HWJT-09C micro-computer excitation equipment
Subject: HWJT series micro-computer excitation control equipment
Applicable to control of IGBT and Thyristor Bridge
Modification records
Modification
index
Chapter
Modification
contents
Pre-modified
contents/modificatio
n date
Modification records
Version
3.0
Compiling
date
Compiled
by
Reviewed
by
Reviewing
date
Wuhan Hongshan Electrical Science & Technology Co., Ltd
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2、 Instructions of the version
Version-3.0 HWJT-09C excitation AVR is the upgraded version of HWJT-08C
micro-computer excitation AVR, which is the third generation excitation regulator
dominated by DSP control chip launched by our company, and which is especially
designed for the small- and medium-sized synchronous generator excitation control
equipment. Version-3.0 HWJT-09C excitation AVR is considerably improved in
functions and greatly strengthened in expandability of control system functions. At the
same time, with modularized interfaces and monitoring functions, it is provided all
interfaces and functions of PSS2A function module, which can adapt to the function
test requirements of the current power network upon the set access network; the
whole regulation & control equipment is significantly improved in terms of the overall
performance.
HWJT-09C excitation regulator is the excitation control equipment primarily
launched by our company currently, which is mainly applied in the small- and
medium-sized synchronous generator excitation control equipment, with the
comprehensive restriction and protection functions. It is totally designed and
processed with SMT process, and completely applies the AC sampling technology,
which provides the touch screens of various specifications (HMI) for selection, as well
as more flexible matching.
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Contents
HEST.........................................................................................................................................1
1、 MODIFICATION RECORDS......................................................................................... 1
2、 INSTRUCTIONS OF THE VERSION........................................................................... 2
CONTENTS..............................................................................................................................3
PART I OVERVIEW.............................................................................................................. 6
PART II FUNCTION SPECIFICATION AND APPLICATION ENVIRONMENT.....10
2.1 MAIN CHARACTERISTICS................................................................................................. 10
2.2 SCOPE OF APPLICATION...................................................................................................15
2.3 FUNDAMENTAL FUNCTIONS.............................................................................................15
2.4 TECHNICAL DATA............................................................................................................ 16
2.5 MAIN TECHNICAL INDICATORS........................................................................................ 17
2.6 SERVICE CONDITIONS...................................................................................................... 18
PART III PRINCIPLE OF EXCITATION CONTROL EQUIPMENT..........................19
3.1 COMPOSITION OF EXCITATION CONTROL EQUIPMENT..................................................... 19
3.1.1 Thyristor power system............................................................................................19
3.1.2. IGBT power system................................................................................................ 19
3.1.3. De-excitation system...............................................................................................20
3.2 DESCRIPTION OF CONTROL PART OF EXCITATION SYSTEM.............................................. 21
3.2.1. Introduction to AVR hardware system.................................................................... 24
3.2.1.1 Input...................................................................................................................... 31
3.2.1.2 Output................................................................................................................... 31
3.2.2. Control power supply..............................................................................................33
3.2.3. Introduction to software system..............................................................................34
3.2.4. Excitation monitoring unit...................................................................................... 44
3.3 COMPOSITION OF POWER PART........................................................................................63
3.3.1. Thyristor power unit............................................................................................... 63
3.3.2. IGBT power system................................................................................................ 65
3.4 DE-EXCITATION AND OVER VOLTAGE PROTECTION EQUIPMENT...................................... 69
3.4.1. Composition of de-excitation and over voltage protection system.........................69
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3.4.2. Operational principle of de-excitation and rotor over voltage protection equipment
...........................................................................................................................................69
3.4.3. Technical specification and common setting calculation method of de-excitation
and rotor over voltage protection equipment.................................................................... 74
3.4.4. Introduction to high energy zinc oxide voltage dependent resistor........................ 77
3.5. INDEPENDENT EXCITATION CURRENT REGULATION CHANNEL (OPTIONAL)....................79
3.6 PLC OPERATION AND CONTROL SYSTEM (OPTION).........................................................80
PART IV OPERATION INSTRUCTIONS FOR CONTROL EQUIPMENT................ 81
4.1 INTRODUCTION TO SYSTEM..............................................................................................81
Regulator and power amplifier power supply...................................................................81
4.2. INSTRUCTIONS OF REGULATOR PANEL........................................................................... 82
4.3 OPERATION INSTRUCTIONS FOR HMI..............................................................................84
PART V EX-FACTORY TEST AND SITE ADJUSTMENT............................................85
5.1 EX-FACTORY TEST........................................................................................................... 85
5.1.1. Inspection and calibration of display state..............................................................87
5.1.2. Signal and switch quantity inspection.....................................................................88
5.1.3. Trigger pulse measurement..................................................................................... 88
5.1.4. Small load waveform observation.......................................................................... 88
5.1.5. Large current test.................................................................................................... 89
5.1.6. Anti-interference test...............................................................................................89
5.2 SITE ADJUSTMENT........................................................................................................... 90
5.2.1. Site wiring inspection............................................................................................. 90
5.2.2. Static test of regulator............................................................................................. 91
5.2.3. Dynamic test of adjuster......................................................................................... 96
5.2.4. Test records........................................................................................................... 104
PART VI BASIC OPERATION METHODS AND MAINTENANCE OF EQUIPMENT
105
6.1 BASIC OPERATION......................................................................................................... 105
6.1.1. Safety requirements and basic regulations............................................................105
SAFETY REGULATION.......................................................................................................... 105
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6.1.2. Input and withdrawal of excitation equipment..................................................... 109
6.1.3. Operation of control unit.......................................................................................110
6.2 ABNORMALITY HANDLING.............................................................................................111
6.2.1. General abnormalities........................................................................................... 111
6.2.2. Fault and abnormality of excitation equipment.................................................... 113
6.3 POINTS FOR ATTENTION FOR OPERATION.......................................................................117
6.3.1. Points for attention for operators.......................................................................... 117
6.3.2. Points for attention for repair and maintenance personnel................................... 117
6.4 BASIC MAINTENANCE.................................................................................................... 118
PART VII EQUIPMENT STRUCTURE.......................................................................... 120
PART VIII ORDER GUIDE...............................................................................................122
8.1 ENVIRONMENTAL REQUIREMENTS................................................................................. 122
8.2 NOTICES FOR ORDER..................................................................................................... 122
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Part I Overview
HWJT-09C micro-computer excitation regulator is the latest generation
micro-computer excitation regulation & control equipment researched and developed
by Wuhan Hongshan Electrical Science & Technology Co., Ltd in 2007, which is
possessed of the following characteristics:
 DSP control chip (foreground) + man-machine interface (HMI) + PLC (option)
hybrid structure
AVR adopts the hybrid structure composed of DSP control chip and intelligent
man-machine
interface
(HMI),
which
achieves
the
better
anti-interference
performance and expands the functions of the excitation regulation & control system.
Main characteristics:

Possessing a minimum number of wires and high reliability;

Being able to adapt to adverse environment such as high temperature, high
humidity, corrosion, vibration & impact and dust;

Possessing
strong
electro-magnetic
compatibility,
high
anti-interface
capability and favorable common-mode rejection ability.
 Excitation
regulation
controller
consisting
of
double-channel
DSP
processor for mutual thermal standby
The control system can select double channels as mutual standby in terms of
redundancy, which involves two standby modes, i.e. cold standby and hot standby.
The cold standby means that only one channel is involved in output under normal
operation of the system, while the other channel traces the operation of the master
channel; such standby mode is usually called master/slave redundancy mode. The
key technology of such standby mode lies in switching, the process of which shall be
reliable. At the same time, the standby channel shall always trace the operation of the
working channel. The judgment and switching circuit independent of double channels
are the disadvantages of such mode, which normally lead to switching problems, i.e.
the master channel may usually fail to be switched to the standby channel.
Hot standby—parallel operation of double channels. The greatest advantage of
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the mode is that double channels are both involved in output under normal operation
of the system.
Double channels of HWJT-09C micro-computer excitation regulator for hot
standby—parallel operation of double channels. In the event of any fault in one
channel, the control system automatically ceases the operation of the faulty channel
through its own software & hardware diagnosis system (WATCHDOG) and mutual
communication. The advantage of such standby mode is that a series of problems
resulting from switching and judgment under master/slave redundancy mode can be
basically avoided, thus achieving high reliability of the system.
The operation mode may also adopt the master/slave standby mode.
 Excitation monitoring unit
The excitation monitoring unit takes the man-machine interface as the main
component, which is the man-machine interaction platform very popular in the
industrial control. The man-machine interface usually enables haphazard selection of
size and color of LCD, and provides the touch screen, which is the general fitting
piece in the industrial field. The man-machine interface is connected with the
excitation regulator unit through RS232C/RS485 serial communication port, thereby
achieving centralized control and management of various component parts of the
excitation system.
The monitoring unit of the excitation system can display voltage, current, active
power and reactive power of generator stator, excitation current (voltage), pulse angle,
generator frequency, fault and abnormity of regulator, idling of generator (network
combination) and on-off state of switches.
Data transmission: the data can be uploaded to the computer-based monitoring
system of the power plant, and the control data can also be received from such
monitoring system through the serial bus (RS232C, RS422 and RS485), site bus
(ProfiBus and CAN) and MODBUS.
 Independent excitation current regulation channel (option)
The totally independent excitation current regulation channels of both hardware
and software take the single chip microcomputer as the control core, and through the
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excitation current (voltage) closed loop PID (PI) regulation, realizes the operation
mode of the generator with constant excitation current (voltage).
 Programmable logical control unit replacing routine logical control wiring
(option)
HWJT-09C excitation regulation system can replace the traditional relay logical
operation control circuit with PLC (programmable controller). Based on the operation
circuit required by different excitation systems, the PLC of different capacities is
chosen (joint number). PLC realizes not only the logical control of the excitation
control system, simplifying the system circuit, but also monitoring of working state,
abnormity and fault of the excitation system.
 Remote drive realized (option)
When the excitation control part is far from the excitation power part, the remote
transmission can be achieved through the tele-transmission function module, and
therefore the problems like attenuation and interference of control signal can be
basically solved.
 Large power switch module power supply, characterized by wide scope of
application and strong anti-interference.
Whether the working power supply of the excitation regulator or the power supply
of the pulse power amplifier can adopts the advanced high frequency switch power
supply or exported power supply module. The large power switch module power
supply, due to taking into consideration the special factors of the excitation system like
peak, medium frequency waveform distortion and large fluctuation range of voltage,
possesses the wider scope of application and better anti-interference performance.
 Switch excitation and thyristor excitation allowed concurrently
Compared with the traditional SCR (thyristor) power unit, the IGBT-based
controllable power unit is characterized by simple, reliable power control link and
greatly reduced power controller parts, thus significantly simplifying the whole power
circuit, improving reliability of the equipment, and achieving convenient maintenance.
All the above-mentioned systems reach satisfactory use effect in the power plant.
Therefore, HWJT-09C excitation regulator takes into full consideration high
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universality of the equipment in terms of design. In this way, it is applicable to not only
the thyristor excitation system but also the switch excitation system, and at the same
time, the double sheath synchronous parallel operation can be realized. It can meet
the synchronous control functions of various AC and DC excitation systems, to enable
the favorable application of the excitation control system, switch excitation power
system or thyristor power system in the generator excitation systems of each kind.
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Part II Function Specification and Application Environment
2.1 Main characteristics
HWJT-09C
micro-computer
excitation
control
equipment
is
primarily
characterized by simple structure, with 32-digit DSP control chip by TI Corporation as
the core and supported by the peripheral interface chip to constitute the main control
module.
1. The excitation regulator AVR can be equipped with two independent auto
channels, which do not share the voltage transformer, current transformer and
stabilized voltage power supply. The double channels adopt the parallel operation or
master/slave operation.
2. The excitation regulator has the on-line parameter setting function. The
background man-machine interface can display the actual value (per-unit value) of the
output quantity of the parameters and function units of the regulator.
3. The time constant of the voltage measuring unit of the excitation regulator is
less than 25ms.
4. The phase shifter of the excitation regulator applies cosine phase shift.
5. The working power supply applies two independent power sources, one
derived from DC power supply system for the plant and the other from AC power
supply system, which varies with the excitation mode.
6. AVR is per se equipped with the perfect software and hardware diagnosis
system, and can automatically cease the operation of the faulty channel when
detecting any fault therein.
7. The excitation regulator is equipped with the perfect restriction and protection
functions.
8. The excitation regulator is equipped with PSS additional control unit, and PSS
adopts double input signals involving electrical power and frequency. PSS has the
functions such as automatic input, manual input, output amplitude limiting
(±5%~±10%) and automatic quit for fault. The output noise of PSS is 2%~5% less
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than output amplitude limit.
9. The excitation regulator has the PT balance protection function, namely, it
prevents faulty force excitation when the circuit of one voltage transformer is
subjected to voltage loss.
10. HWJT-09C regulator also has the following functions:
1) Self diagnosis function and examining and adjusting software and
interfaces for various functions;
2) Connecting serial port with computer monitoring system of power plant,
receiving control and regulation commands, and providing state and value of
quantity of excitation system;
3) Event sequence recording function.
4) Intelligent detection and operation function:
 Power detection: the system has the power detection function, which
is mainly used to detect and real-time display the temperature of primary power
parts of the system; when the temperature is higher than the set value, the cooling
fan is automatically started, and the alarm signal is sent out;
 Over current detection: the system real-time detects and display the
current of power elements; when over current occurs, the outlet switch of the
circuit is automatically tripped, with faulty point cut off and alarm signal sent out;
 Pulse detection: the system real-time detects the pulse output state of
the regulator; when the pulse is lost, the alarm signal is sent out;
 Monitoring of working power supply of the regulator: under normal
operation, the regulator is supplied with power by AC and DC power source for
the power plant; when the power source disappears (or its input or output exceeds
the limit), the alarm signal is immediately sent out;
 The system real-time detects the temperature of the excitation
transformer; when the temperature is higher than one set value, the cooling fan is
automatically started, and the alarm signal is sent out.
11. Manual excitation control mode can meet the excitation equipment test and
generating set test. Both channels can be manually or automatically switched without
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any fluctuation.
Application specification and technical indicators:
The technical performance of the regulator can meet the technical requirements
of DL/T650-1998, DL/T583-1995 and Synchronous Motor Excitation System
GB/T7409.3-1997:
When HWJT-09C excitation regulator is used to form the generator excitation
system, the generator excitation system shall meet the following technical indicators:
The excitation system shall fully meet the requirements such as power generation,
peak adjustment, frequency adjustment, phase adjustment, synchronous paralleling,
line charging, phase advance running and zero-starting voltage step-up with line.
The increase in the voltage response time of the excitation system shall not be
more than 0.08s, and the decrease therein shall not be more than 0.10s.
The delay time of the excitation system shall be less than 0.02s.
The static voltage difference rate of the generator shall be ±0.5%.
When the voltage of the generator is boosted from zero, the maximum value of
the generator voltage of the excitation regulator shall not be more than 110% of rated
value, the number of oscillations shall not be more than 3 times, and the adjustment
time shall not be more than 10s.
The given step response of the voltage of the excitation control system shall meet
the following items: no-load step response: the overshoot shall not be more than 30%
of step quantity, the number of oscillations shall not be more than 3 times, the
increasing time shall not be more than 0.08s, and the response time shall not be more
than 5s.
When the generator is with the rated reactive power, the maximum voltage of the
generator shall not be more than 115% of the rated value.
The excitation voltage regulator conducts stable, smooth adjustment within the
range of 10%~130% of the no-load rated voltage of the generator. The voltage
resolution shall not be more than 0.5% of the rated voltage.
The manual control ensures that the generator excitation voltage can be stably
and smoothly adjusted between 10% of the no-load rated excitation voltage and 110%
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of the rated excitation voltage.
Under no-load operation state of the generator, the given voltage regulation
speed of the excitation regulator shall not be more than 1% rated voltage/s or less
than 0.3% rated voltage/s.
The regulator adopts the reactive difference adjustment for the generator voltage.
The range of the difference adjustment shall not be less than ±10%.The setting of the
difference adjustment rate undergoes the split adjustment throughout the process.
When the generator is involved in the no-load operation, the change in frequency
is 1%, and the voltage fluctuation at the generator end shall not be more than ±0.25%
of the rated value.
The mean time between failures (MTBF) of the excitation regulator shall not be
less than 24,000h, the annual forced disengaging ratio shall be less than 0.04%, the
mean time to failure of the excitation equipment shall be less than 4h/year, the
utilization rate shall be more than 99.0%, and the failure rate shall be less than 0.25
time/set-year.
Within the following deviation range of the power voltage and frequency for the
power plant, the excitation regulator ensures its long-term continued normal
operation.
For the AC 380/220V system, the voltage deviation range is ±15％ of the rated
value, the frequency deviation range is -3 ～ +2 ％ HZ; for the DC 220V system, the
voltage deviation range is -20％～+10％ of the rated value.
When the short-time fluctuation range of the AC working power supply is
55%~120% of the rated value, the excitation regulator ensures its normal operation
and the smooth operation of the force excitation and rapid excitation.
For the electrical devices or components of the excitation regulator directly
connected with the excitation winding in terms of electricity, when the rated excitation
voltage of the generator is not more than 500V, the ex-factory power frequency test
voltage shall be 10 times the rated excitation voltage, the minimum value of which
shall not be less than 1,500V; when the rated excitation voltage of the generator is
more than 500V, the ex-factory power frequency test voltage shall be 2 times the
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rated excitation voltage plus 4,000V.
The power frequency test voltage of other electrical components is as follows:
when the rated working voltage is 12V~60V, the power frequency test voltage shall be
500V; when the rated working voltage is 60V, the power frequency test voltage shall
be 2 times rated working voltage plus 1,000V, the minimum value of which shall not
be less than 1,500V.
The ex-factory test voltage for 200V DC power circuit shall be 2,500V. The
ex-factory test voltage for the 380V circuit of the system for the power plant shall be
3,800V. Other ex-factory test voltage is in accordance with the pertaining provisions.
For the 500V megameter for signal line, the insulation resistance shall be more
than 10M; for the 1KV megameter for power line, the insulation resistance shall be
more than 10M.
When being subjected to any electro-magnetic interference like electrical
operation, thunderbolt, static electricity and radio transceiver, the excitation regulator
will not suffer mis-adjustment, maladjustment, accidental operation and refused
operation.
The excitation regulator is equipped with the software and hardware for the
interfaces of the computer monitoring system. The interfaces are divided into three
modes, i.e. computer data communication, switch quantity and analog quantity.
The data communication may adopt serial bus (RS232C, RS422 and RS485),
site bus (ProfiBus and CAN), and so on.
All inputs of the switch quantity shall be passive nodes, and the detection reveals
that the power supply is ＋24V（220V）3mA, serial resistance is less than 10, and
the parallel resistance is more than 1M ; all outputs of the switch quantity shall be
passive nodes, and the capacity and resistive load are 24 ～ 220Vdc and 5A
respectively.
The output signal of the analog quantity is 4mA~20mA (or 0~5V), with precision
of 0.5%.
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2.2 Scope of application
HWJT-09C series micro-computer excitation equipment has great adaptability
and universality, which can be applied in 200MV and below various synchronous
generating sets. The excitation system includes:
1. DC excitation system:
Input DC voltage:
30V～300V
Output current:
5A～100A
2. Three-generator excitation system:
Input voltage:
90V～130V
Input frequency:
50Hz～500Hz
Output current:
50A～300A
3. Double-generator AC excitation system:
Input voltage:
50V～500V
Input frequency:
50Hz～500Hz
Output current:
50A～500A
4. Self shunt excitation system:
Input voltage:
50V～1000V
Output current:
300A～3000A
2.3 Fundamental functions
 Operation mode of generator with constant terminal voltage
 Operation mode of generator with constant terminal current
 No-load over-voltage protection
 Force excitation upper limit
 Over excitation opposite time limit
 Low excitation limit
 Breakage detection and protection of excitation/instrument voltage
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transformer
 V/F limit, low frequency protection
 Optional positive and negative difference adjustment rate
 Start-up voltage auto setting and shut-down voltage auto resetting
 PID and PI control & adjustment, additional PSS adjustment and
self-adaptive adjustment of variable parameters (optional)
 Communication interfaces with other auto instruments and computer
monitoring system
 HMI LCD touch screen, online displaying multiple parameters
 Pulse output double-layer vibration isolation, panel measurement and
indication
 Output of fault signal of power supply, hardware and software and other
fault signals
 On-line modification of control parameters
 Software anti-mal-operation locking
 Power supply with double power sources, panel measurement and state
signal indication
 Power-off data protection
 One-key start-up function
2.4 Technical data
1. Generator terminal voltage UF:
Rated value at secondary side of
voltage transformer 100V or 105V
2. Stator current measurement IF:
Rated value 5A input or 1A input
3. Rotor current measurement IL:
Hall current sensor measurement
4~20mA or 0~5V signal input
4. Output pulse:
50Hz~500Hz thyristor trigger pulse (thyristor
excitation system)
Output pulse:
50Hz~300Hz
duty
ratio
of
variable
rectangular wave (IGBT excitation system)
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5. Output range of excitation current:
50～3000A
6. Output range of excitation voltage:
50V~1,000V (thyristor excitation
system)
7. AC and DC parallel power supply:
AC input 220V+10%，-20%
DC input 220V+5%，-15%
2.5 Main technical indicators
1. Pulse adjustment range:
10～150(thyristor excitation system)
Variable range of duty ratio of rectangular wave:
0%～100%
2. Pulse width adjustment precision:
Superior to 0.0036 
(50Hz
thyristor excitation system); 0.036 (500Hz system)
Pulse width adjustment precision of rectangular
wave: superior to 0.01%
3. A/D switching resolution: Superior to 2 － 12
4. Adjustment speed:
3ms/period
5. Voltage adjustment range:
10% ～ 130%Ue(manual 10% ～
110%Ue)
6. Voltage adjustment precision:
Superior to 0.5%
7. Difference adjustment characteristics:
±15%
can be
set,
step
length 0.1%;
8. Frequency characteristics:
Frequency change 1%, the change
of generator terminal voltage is less than ±0.1% of rated value
9. Frequency range:
40～77.5Hz
10. Given adjustment speed:
Not more than 1%/s, and not less than
0.1%/s
11. 32-digit DSP processor adopted: main frequency 125MHz
12. Excitation PT and IF, instrument PT, system PT and 12-digit AD for AC
sampling
13. FFT AC sampling algorithm
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14. 36-point 12-digit AD synchronous sampling
15. Built-in PSS software module of PSS2A module applied
16. Complete PSS testing interface
17. Isolating RS-232C/RS-485 communication interfaces, and supporting
standard ModBusRTU communication protocol
18. Man-machine interfaces (HMI) of several specifications for choice,
printer and micro printer supporting inking and laser.
19. Power consumption:
Less than 25W.
2.6 Service conditions
1. Installation location: indoor;
2. Ambient temperature is －5℃～＋45℃;
3. Storage temperature is -25℃～＋75℃;
4. Height above sea level: ≤2000m; relative humidity: ≤90%, without
condensation;
5. Installation vertical inclination: ≤5°;
6. When the allowable vibration is 10~150Hz, the vibration acceleration shall not
be more than 5m/s2;
7. Seismic fortification intensity: ≤ magnitude Ⅷ;
8. The surrounding medium of the service environment shall be free from any
explosion risk and corrosive gas, and the concentration of the conductive dust
contained shall not reduce the insulation level to the allowable limit value.
9. When the altitude exceeds 1,000m, the relevant regulations on maximum air
temperature are as follows:
Height
above
sea level (m)
Maximum
air
temperature (℃)
H≤1000
50
1000<h≤1500
47.5
1500<h≤2000
45
2000<h≤2500
42.5
When the conditions of the service environment exceed the above regulations,
they shall be expressly indicated in the order.
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Part III Principle of Excitation Control Equipment
3.1 Composition of excitation control equipment
The excitation system is composed of control part, power part and DC output part.
The regulation & control part is constituted of double-sheath (or single sheath)
HWJT-09C micro-computer excitation regulator and switching control link of input and
output of various signals.
3.1.1 Thyristor power system
The power part is mainly made up of three-phase bridge thyristor, and the self
shunt static excitation system consists of micro-computer excitation regulator box,
thyristor power part and de-excitation part. The function units can also form the
cabinets independently (the parallel quantity of the power cabinets are increased
depending on the excitation current).For the three-generator excitation system and
double-generator AC excitation system, the control part and power part can be
separately located within one cabinet, to form one standard excitation control cabinet.
The generator excitation control equipment is constituted of the equipment end
excitation transformer (self shunt static excitation system), excitation regulator,
thyristor power unit, de-excitation part and operation measurement.
3.1.2. IGBT power system
The power part is made up of the three-phase non-controllable rectifier unit (the
DC excitation system requires no such unit), one set or multiple sets of IGBT switch
control units and relevant filtering and protective circuit.
In the three-generator excitation system (or double-generator excitation system),
the power part is one set of three-phase rectifier bridges and one or more IGBT
switch pipes, which is installed in one cabinet with the micro-computer excitation
regulator. The over 100,000kw set normally applies the operation mode of parallel
double cabinets for hot standby, thus further improving reliability.
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For the self shunt static excitation system, two micro-computer excitation
regulator casings form one excitation regulator cabinet; in addition, the three-phase
rectifier bridge and IGBT power switch pipe form the power cabinet, the quantity of
which is based on the magnitude of the generator excitation current.
3.1.3. De-excitation system
The de-excitation and rotor over voltage protection equipment is made up of the
zinc oxide voltage dependent resistor components and exclusive rapid DC switches,
which is characterized by simple operation, rapid de-excitation speed, large switch
capacity and controllability of over voltage protection level, and which is applicable to
the de-excitation of large- and medium-sized generating set and over voltage
protection of the rotor.
The main technical requirement of the de-excitation of the generating set is as
follows: while the rotor voltage of the setting-off de-excitation does not exceed the
allowable value of long-term safe, stable operation, the de-excitation time shall be
short as much as practicable. The de-excitation and over voltage protection system
may be composed of various magnetic filed breakers and de-excitation resistors; in
terms of the de-excitation mode, the de-excitation equipment formed by single break
de-excitation switch and the de-excitation equipment made up of double-break
de-excitation switch are divided into the linear de-excitation equipment, non-linear
de-excitation equipment and contact-free de-excitation equipment, each of which can
meet the needs of matching the home-made generating sets.
The de-excitation and over voltage protection system is flexibly assembled.
Based on the de-excitation capacity of the generating set, it can form the whole panel
together with adjustment part and power part, and can be also indepently assembled
into the cabinet.
The whole generator excitation system is also composed of the excitation
regulator, power unit, de-excitation unit and other units.
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3.2 Description of control part of excitation system
HWJT-09C micro-computer excitation regulation system is mainly composed of
the following parts:
1. DSP controller
2. Excitation monitoring unit
3. Independent excitation current regulation channel (option)
4. Programmable logical control circuit (option)
5. Power output of regulation system
1) Power rectifier bridge (which is divided into thyristor bridge and IGBT
switch type power output)
2) Generator de-excitation equipment (linear de-excitation and non-linear
de-excitation)
3) Over voltage protection equipment of generator rotor
4) Initial excitation equipment
General functions of excitation regulator
 Functions of “frequency measurement disappearing” and “synchronism
disappearing”
The “frequency measurement disappearing” and “synchronous disappearing” are
the signals sent out by the control chip when it does not receive the “frequency
measurement” or “synchronous” pulse, which are used to monitor the internal working
state of the excitation regulator.
The “frequency measurement disappearing” warning is one relatively important
working state. The “frequency measurement disappearing” is used to control the FFT
AC and DC sampling frequency in the regulator, and also the main method of
rectifying the SCR pulse output angle. When the “frequency measurement
disappearing” acts, the default frequency is 50Hz. The regulator applies the fixed
frequency of 50Hz to control the sampling frequency and rectify the SCR pulse output
angle.
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 Function of “constant reactive” and “constant power factor”
The “constant reactive” and “constant power factor” is one control function
attached to PID.
 Function of “hard start-up” and “soft start-up”
Increasing time of auto soft start-up: it refers to the given increasing time from the
initial given value of soft start-up to auto soft start-up goal. The setting principle of the
increasing time is that the given increasing speed shall not be more than 0.5%/s.
The “hard start-up” means that the given value directly increases to the pre-set
value when the start-up occurs.
 Function of “network voltage tracing”
The “network voltage tracing” produces some effect in the “hard start-up”, since
the given value is directly set to the power network voltage value in start-up.
 Start-up, initial excitation and failure of initial excitation
The “start-up” conditions are not connected to power network, UF＜5～30%, and
the regulator is free from any signal of abnormality and failure of initial excitation, and
receives the valid start-up command. The regulator sends out the signal of “initial
excitation”. When the duration is 5s and UF>30%, the regulator ceases its operation;
when the duration is more than 5s, the regulator ceases its operation, and sends out
the signal of “failure of initial excitation”; when the duration is more than 30s, the
regulator resets the signal of “failure of initial excitation”.
While sending out the signal of “initial excitation”, the regulator starts the program
of “hard start-up” and “soft start-up” pursuant to the pertaining conditions, to initialize
the excitation and sets up voltage.
 Double-set communication of regulator
The regulator hardware has the configuration of double-set communication,
which is utilized to complete the data exchange between regulator A and B and
coordinate the difference between these two regulators.
The regulator has one isolated RS232 full-duplex communication interface, which
is utilized to complete the data exchange between redundant regulators. These two
regulators exchange the data acquisition quantity, working state signs, various given
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outputs and control ring outputs between each other.
The regulators coordinate their difference through these data, to enable the
parallel operation of these two regulations and then to cooperate together in
completing the same work, to accomplish the purpose of hot standby.
 Master/slave function of regulator
The master/slave function is for the purpose of better coordinating the difference
between these two regulators, which is one of the indispensable conditions for
parallel operation of them.
The master/slave function affects the control of the regulator in two respects.
1: Double-set tracing
During the course of long-term operation of the regulator, owing to the subtle
difference of hardware circuit (e.g. measurement, magnetism enhancing and
reducing operation) and high magnification factor in PID link, coupled with the time
accumulation, the greater accumulated difference may occur in the final output. The
method of adjusting or reducing the error is to determine the tracing direction.
The “slave” regulator set actively traces the “master” regulator. In this way, the
final output (control voltage) is made to approach the “master” regulator.
Tracing conditions are as follows:
 Double-regulator communication is in normal condition;
 The body is the “slave” regulator, while the other is the “master” regulator;
 Both regulators are free from any “abnormality” signal;
 The control voltage of the “master” regulator is 0.05v~0.75v.
The final goal of tracing is to make the control voltage of the “slave” regulator is
0.01v lower than that of the “master” regulator, and to adjust the dead zone to be
±0 .001.
2: Constant reactive and constant power factor
Two kinds of circumstances are involved:
 Only If the “communication” is in normal condition, and one regulator is
the “master” regulator and the other one being the "slave” regulator, the
“master” regulator has the function of “constant reactive” or “constant
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power factor”.
 If the “communication” is not in normal condition, the “master” regulator
has the function of “constant reactive” or “constant power factor”, while
the “slave” regulator does not.
3.2.1. Introduction to AVR hardware system
HWJT-09C excitation regulator is of modularized structure, which can form the
adaptive redundant system through replacing, increasing or reducing the modules,
based on the requirements of different excitation systems.
As the core control link
adopts the modularized structure, without any exterior bus, the reliable framework of
the bus is unnecessary to be considered; in addition, as the connection between
modules applies the rapid data exchange technology, and at the same time, during
the deign the consummate single module function and SMT element are applied to
reduce the area of the circuit board, the minimum number of interconnected lines
among modules is ensured, and the equipment reliability can be greatly improved.
The structural layout of the micro-computer excitation controller is shown in the
following figure (reference drawing).
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HWJT-09C 系列微机励磁调节器 HWJT-09C series micro-computer excitation regulator
电源 Power supply
并网 Network connection
异常 Abnormality
运行 Operation
空载 No-load
增磁 Magnetism enhancing
减磁 Magnetism reducing
手动 Manual
灭磁 De-excitation
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切脉冲 Pulse pruning
 Panel setting
On the panel there are 5 buttons, 14 luminotrons and one switch. They are:
A. Buttons: pulse pruning—red with lamp, lock and protective over;
Magnetism enhancing and reducing—red without lamp, lock or
protective cover;
Manual, de-excitation--—red without lamp, lock or protective cover;
B. Luminotrons: operation—flash green luminotron;
Power supply—long bright green luminotron;
Network connection, PSS, master/slave, communication, constant PF input
and constant COS input—green luminotrons;
Manual,
de-excitation,
abnormality,
over
excitation
and
fault—red
luminotrons;
C. Switch: black switch—switch for working power supply of the module
 Simulation input signal
The simulation signal input of the module applies the high precision linear
variable current isolation technology. The isolation switching of two three-phase AC
voltage, one two-phase AC voltage and two three-phase AC current is achieved, as
shown in the following figure. The application of high performance variable current
part and active switching ensures higher electrical isolation (>3,000V), and acquires
the linearity and phase distortion of the signal switching which are greatly superior to
those of the conventional transformer and converter. The linearity of signal switching
is better than 0.1%, and the phase shift is less than 5mm.
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Through the isolation switching, the module is at most able to switch the signals
of one set of excitation PT, one set of instrument PT, one set of system (bus bar) PT,
one set of generator stator CT and one set of generator general excitation current CT,
and outputs the standard AC voltage signals through conversion.
Excitation PT and instrument PT:
(100V or 105V) three-phase positive
sequence Δ/Y－12 input;
Synchronous UT:
(100V or 105V) three-phase positive
sequence Δ/Y－11 input;
System PT:
Stator IF and rotor IL:
（100 V or 105 V）single phase input；
(5A or 1A) three-phase positive sequence
Y/Y0-12 input.
Simulation signal conversion circuit:
The module mainly acquires the excitation PT voltage, instrument PT voltage,
system PT voltage, synchronous voltage, rotor voltage, stator current, rotor excitation
current (LEM), rotor AC current, excitation current (LEM) of the regulator and
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excitation current (AC) of the regulator. The primary function of the signal processing
circuit inside the module is to convert the analog quantity signal required by the
excitation regulation system into the signal accepted by the DSP processor for
handling by DSP processor.
The DC quantity of the module directly comes inside, while AC quantity enters
inside through internal PT and CT conversion. Such as the excitation PT voltage,
instrument PT voltage, system PT voltage, synchronous voltage, rotor voltage, stator
current, rotor excitation current (LEM), rotor AC current, excitation current (LEM) of
the regulator and excitation current (AC) of the regulator in the above-mentioned
acquisition quantity.
HWJT-09C AVR applies the AC sampling algorithm. The AC sampling method is
to acquire the voltage and current quantity required by the excitation regulation
system directly through DSP, and at the same time, to calculate the voltage, current
and power quantity corresponding to the acquisition time. Such AC sampling method
requires less hardware, accompanied by flexible signal processing and high operation
reliability.
The AC sampling method involves 36 points each cycle, with 12-digit precision,
applies the FFT algorithm, and within the full range of signal switching filter off the
waveform interference arising during the switch-off and phase shifting of such
elements as large power thyristor, diode and IGBT, thus improving measuring linearity
and accuracy.
The unit can, based on the measurement of difference excitation systems,
acquire the standard analog quantity signals: excitation PT, instrument PT, stator IF,
system PT, synchronous UT, rotor UL, rotor IL, IL of the regulator, active power,
frequency measurement and synchronous trigger pulse signals.
 Input & output channels of switch quantity
Under general circumstances, the module has a total of 10 output channels for
the relay (including one standby signal) and 10 input channels for switch quantity
(including one standby signal):
Signal description
Signal type
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Signal
Remarks
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direction
Magnetism
Button of the
Regulator
The
enhancing
regulator/active joint
input
panel/remote
Magnetism
Button of the
Regulator
The
reducing
regulator/active joint
input
panel/remote
Manual
Button of the
Regulator
The
regulator/active joint
input
panel/remote
Active joint
Regulator
The
input
panel/remote
Regulator
Remote
Start-up
Network
Active joint
connection
De-excitation
Force elimination
input
Button of the
Regulator
The
regulator/active joint
input
panel/remote
Active joint
Regulator
The panel
input
PSS remote input
Active joint
Regulator
Remote
input
Standby
Active joint
Regulator
input
Pulse pruning
Button
of
regulator
Abnormality
Fault
Initial excitation
Failure of initial
Passive joint
Passive joint
Passive joint
Passive joint
excitation
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the
Regulator
The panel
input
Regulator
The
output
panel/remote
Regulator
The
output
panel/remote
Regulator
The
output
panel/remote
Regulator
The
output
panel/remote
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Fan
No-load over
Passive joint
Passive joint
voltage
PSS input
Passive joint
operation
Constant reactive
Passive joint
input
Constant PF input
Standby
Passive joint
Passive joint
Regulator
The
output
panel/remote
Regulator
The
output
panel/remote
Regulator
The
output
panel/remote
Regulator
The
output
panel/remote
Regulator
The
output
panel/remote
Regulator
output
A phase pulse
Pulse signal
Regulator
The panel
output
B phase pulse
Pulse signal
Regulator
The panel
output
C phase pulse
Pulse signal
Regulator
The panel
output
-A phase pulse
Pulse signal
Regulator
The panel
output
-B phase pulse
Pulse signal
Regulator
The panel
output
-C phase pulse
Pulse signal
Regulator
The panel
output
Positive group
Pulse signal
PWM pulse
Reverse group
Regulator
The panel
output
Pulse signal
PWM pulse
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Regulator
The panel
output
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3.2.1.1 Input
All I/O inputs of the module include 9 exterior joint inputs and 5 button inputs of
the regulator.
5 button inputs of the regulator include magnetism enhancing, magnetism
reducing, manual, de-excitation and pulse pruning.
9 exterior joint inputs include start-up, network connection, manual, de-excitation,
magnetism enhancing, magnetism reducing, force elimination, PSS remote input and
standby.
9 exterior joint input control signals are as follows:
Magnetism enhancing—increasing given Ug or Ig
Magnetism reducing—reducing given Ug or Ig
Manual—operation mode of constant excitation current
De-excitation--① network connection: invalid; ② Disconnection: given resetting
and de-excitation
Start-up--① Network connection: invalid; ② Disconnection: when UF <30V, set
Ug to the set value or corresponding value of system PT voltage
Network connection—generator outlet breaker (DL switch) state
Force elimination—power cabinet fan sate or power unit temperature state
PSS remote input—remote control PSS function input
Standby—standby input channel
9 exterior signals, after undergoing optocoupler isolation and treatment of
anti-interference and error protection, are sent to DSP host computer board.
3.2.1.2 Output
All node outputs include abnormality, fault, initial excitation, failure of initial
excitation, fan, no-load over voltage, PSS input, constant PF input, constant COS
input and standby.
6/2 trigger pulses: A phase pulse, B phase pulse, C phase pulse, -A phase pulse,
-B phase pulse, -C phase pulse/positive group PWM pulse and reverse PWM pulse.
 DSP control core board
The DSP control core board adopts the DSP control chip imported from American
IT Corporation, which is 32-digit rapid digital signal processor, with main frequency of
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125MHz.
The circuit design is simple and reliable, which ensures the normal operation of
the system when the excitation monitoring unit (HMI) withdraws from the operation.
The independent automatic and manual control functions meet the user’s normal
and special excitation control requirements, and the anti-error double-way tracing
technology is adopted, to realize the standby channels (“auto” and ”manual”) and
full-process tracing working channels (“auto” and ”manual”);
The host computer board outputs the pulse signals with certain load carrying
capacity: 6-phase thyristor trigger pulse (or 2 positive and reverse group PWM pulses),
which can not only control the single-set power circuit, but also accurately transmit the
trigger control signals of multi-set power units.
Main characteristics:
 The current advanced 32-digit control type DSP is adopted;
 Internal multiple frequency technology, external frequency 25MHz and
operating speed 125MHz;
 Multi-layer (6-layer) board design, high reliability, fine stability and good EMC
performance;
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 32-digit command single-cycle execution capacity, which reaches 0.15 billion
commands/s;
 32x32
hardware
multiplier
and
64-digit
shift
accumulator,
ensuring
high-precision data calculation ability and extremely great processing speed.
 Rapid 12-digit and 36-point each cycle AC sampling;
 Tracing & synchronous sampling technology:
 FFT (Fourier) algorithm, which can directly calculate the voltage, current,
active power and reactive power at the generator side;
 Each cycle 36-point sampling technology, which avoids frequency spectrum
leakage and reduces measuring error;
 FFT calculation applies the sliding data window technology, which increases
the calculation speed, and the response time of actual measurement is 25ms
(tested by North China Electric Power Research Institute).
 3-meter AC sampling technology, which not only samples Ua, Ub, Uc, Ia, Ib
and Ic, but also effectively avoids the measuring error caused by LPT and
generator CT faults.
3.2.2. Control power supply
The control power supply is the high performance industrial high-frequency
switch power supply, which can ensure the reliable operation of the modules; the
circuit board module and power supply module are shown in the following figure. The
power supply of the control system applies the mode of double power sources, the
voltage from which is supplied to the power supply module after power supply
combination; the main characteristics are as follows:
 Scope of power supply
Scope of application of working power supply under normal conditions:
Three-phase line voltage input:
When the rated voltage is 220V, it is
60V~270V;
DC Input voltage:
When the rated voltage is 220V, it is100V~400V;
When the rated voltage is 110V, it is 50V~200V;
The AC input can adopt the self excitation transformer, excitation PT, AC power
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supply for power plant and permanent magnetic machine.
 Fine interchangeability
AC power supply and DC power supply are interchangeable in use.
 High reliability
The power supply has powerful anti-interference capacity, stable output and high
precision;
3.2.3. Introduction to software system
The design of HWJT-9C AVR software system complies with the following
principle:
1. The scientific software structural design is adopted, to improve the operating
speed and reliability of the system;
2. The software modules possess strong independence, high efficiency and high
reliability;
3. The program of each module is brief and efficient, facilitating the detection of
the program;
4. Each module ensures its tightness and clarity of flowing direction;
5. Each variable and sign has its strict scope of utilization, thus improving the
anti-interference capacity of the data;
6. The module may be regarded as one process of input, treatment and output,
namely, IPO (Input Process Output) form of module. For the modules connected in
sequence, the output of the former module should be the input of the next module as
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much as possible, to avoid the extra switching, such as the connection of working
procedures in the streamline, thus improving efficiency and reliability.
7. Standardized data processing converts all external input data into per-unit
value for computation, which improves the standardization of both data and program,
avoids the complication of working data due to different parameters of the excitation
system and prevents unnecessary overflow of large data and low precision of small
data.
Sub-program modules: given adjustment, protection and judgment of switch
quantity, acquisition, power calculation, restriction and protection, PID, PSS, selection
of adjustment mode (P, PI, PD and PID), selection of positive and negative difference
adjustment and magnitude of difference adjustment rate, manual tracing auto, auto
tracing manual, double-set control unit communication and upper machine
communication. Flow chart of primary program principle is as follows:
上电 Connected to the power supply
监测 Monitoring
复位 Resetting
CPU 自检 CUP self inspection
PSD 自检
PSD self inspection
参数自检 Self inspection of parameters
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PSD 初始化 PSD initialization
系统初始化 System initialization
给定调节 Adjustment of given value
开关量检测 Detection of switch quantity
采集 Collection
功率计算 Power calculation
限制和保护 Restriction and protection
自动 PID Auto PID
手动低励 PID Manual low excitation PID
PSS
控制方式选择 Selection of control modes
自动手动跟踪 Auto/manual tracing
通讯 Communication
参数自检 Self inspection of parameters
状态自检 Self inspection of state
WATCHDOG
HWJT-9C application program includes two parts, i.e. primary program and
control & regulation program.
 Flow and function of primary program
1. System initialization
As the regulator begins to operate, the system initialization program conducts
setting of the mode and initialization state of the computer board and interface board,
including initialization of interruption and initialization of serial port and parallel port;
when the initialization is completed, the adjustment gets ready. Once the initial
excitation conditions are met, the regulator will immediately enter into the regulation
and control state.
2. Judgment of start-up conditions and setting before start-up
As the start-up conditions vary with the power plants, the program will, based on
the start-up conditions of the power plants, first judge whether the initial excitation
occurs or not.
The setting before start-up is to set given value for voltage, and reset some fault
restriction signs.
3. Start-up interruption
When the start-up conditions are met, the micro-computer excitation regulator
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will enter into the regulation & control state. As the regulation and control program
serves as the interruption program, the interruption operation shall be started. After
the interruption operation begins, the interruption signal may come into existence,
and CPU will interrupt the execution of the master program and start the execution of
the interruption program. When the interruption program is finished, the execution of
master program will be restored and continued.
4. Setting of fault detection
The regulator is provided with the fault detection programs for the excitation
system, which are placed in the master program or interruption program based on the
real-time requirements, such as PT breakage judgment, stabilized voltage power
supply detection, self recovery and hardware detection signal.
5. Terminal display and micro-computer command interface
In order to monitor the operation situation of the generator and regulator, the
industrial control machine is utilized to display on the screen some parameters and
quantity of state in a dynamic manner.
During the course of adjustment, some parameters shall be altered, so they can
be input through the interface of the industrial control machine. Through the
man-machine interface command, some dynamic tests are also enabled, such as
10% step response (see the operation manual for the adjustment equipment for
specific operation).
 Flow and function of control & regulation program
The control & regulation program flow of the micro-computer excitation regulator
is as shown above. The no-load inversion conditions are as follows:
(1) Shut-down command;
(2) The terminal voltage is more than 130%, or the rotor current is more than
rated value of the load;
(3) The frequency is less than 45Hz;
If any of the above-mentioned conditions is met, the control & regulation program is
converted into the inversion de-excitation program; otherwise it is converted into the
regulation & control calculation program.
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1. Adjustment calculation of voltage
The adjustment calculation of the voltage is primarily composed of three parts, i.e.
sampling, difference adjustment calculation and PID calculation. The difference
adjustment calculation is a reactive compensation as the reactive power is rationally
distributed among parallel sets when the unit wiring is expanded.
2. Power plus frequency PSS module
PSS controller is one standard software module of large generator excitation
regulator, whose function is to support the control excitation output, for the purpose of
inhibiting low frequency oscillation of the generator and improving the stability of
power network.
PSS2A module of our company’s double input signal (power plus frequency) is as
follows:
Tw3S
1 + Tw3S
f
Tw4S
1+ Tw4S
+
+
 1  T6 S

M
 (1  T7 S )



N
+
-
Ks3
Pe
Tw1S
1 +Tw1S
Tw2S
1+Tw2S
Ks1
1+T1S
1+T2S
Ks2
1+T5 S
1+T3S
1+T4S
PSS out
The function module is put into operation when the generator power exceeds
certain value, and automatically withdraw from its operation when the generator
power is lower than such value, to avoid over voltage in the generator under the
impact of PSS when the system rejects the load; in case the function module is put
into operation manually, it will automatically withdraw from its operation when being
subjected to fault or failure.
The output amplitude limit of the PSS is ±5%～±10%, and the output noise is less
than 2%～5% of the output amplitude limit
The frequency characteristics of PSS have relatively stable phase compensation
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when being within the wider frequency band.
3. Restriction flow
The generator in service is provided with many restriction functions, to ensure
safe operation and uneasy tripping. The current micro-computer excitation regulator
is provided with, when the generator is without load, maximum magnetic flux V/F
restriction, inverse time limit force excitation upper restriction, lagging phase reactive
inverse time limit or time delay restriction and leading phase reactive instantaneous
restriction. The restriction judgment program is to judge whether the generator enters
into these restriction states or not. As these restriction characteristics are always
linear, they shall be judged based on the non-linear curve of these characteristics.
◆V/f restriction
V/f restriction is to avoid the generator and its outlet transformer from
suffering magnetic saturation. V/f restriction is put into operation, when the generator
is not connected with network, V/f restriction switch is input, the frequency is less than
V/f failure threshold, and no abnormality occur. When the generator frequency is less
than V/f failure threshold, the given value of the voltage is restricted to no more than
UFG1; when the frequency is further reduced, the given value of the voltage is
restricted in terms of the curve; when the frequency is less than 45Hz, the lower
frequency protection acts, and the inversion de-excitation program is started. When
the generator frequency is more than V/f failure threshold, the low frequency
protection does not participates in the control & regulation.
L
UREF'
A
0
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C
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Calculation formula: U G '  UF G 
Where:
F
U 0
F0
UG′ is UG restriction value calculated
UFG is the given value of V/f restriction
F is the current generator frequency, Hz
F0 is the given value of the generator frequency, 50
U0 is the rated per-unit value of the voltage at the generator side,
1
◆ Low frequency protection
The low frequency protection is put into operation when the generator is not
connected to the network, and automatically withdraws from its operation when the
generator is connected to the network. The restriction function is without restriction
switch. When the frequency is less than the “given value of low frequency protection”,
the excitation regulator proceeds with the inversion de-excitation, and resets all given
values.
◆ Forced restriction judgment
The force excitation restriction is the excitation restriction measure adopted for
avoiding over current of generator rotor excitation winding. In terms of the heat
generation of the rotor excitation winding, when the force excitation occurs, the
maximum excitation current of the generator is restricted.
The force excitation restriction is controlled by PI current closed loop. After the
force excitation restriction is started, the force excitation output control angle acts;
when the excitation current exceeds the set value, AVR control is transformed from
the voltage closed loop adjustment to PI current closed loop control, thus restricting
the rotor current within the scope of the given value.
◆ Over excitation restriction judgment
When the generator excitation current (voltage) exceeds the rated value (1.1
times), the excitation current will undergo the inverse time limit and delay restriction.
After the inverse time limit and delay restriction acts, AVR is controlled by the PI
current closed loop, to achieve steady, smooth transition of the excitation equipment
to steady operation at restriction value.
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In accordance with the principle that the heat generation of the generator rotor is
in direct proportion to the current square, the over excitation delay time is calculated in
the square of the specific value of the excitation current or voltage to rated value.
When the over excitation acts, the regulator will make two actions.
1. PID output result may be more than restriction value, and at this point, PI
current closed loop outputs the restriction value as the result. If the output result of
PID is less than restriction value, the PID result is directly output.
2. When IL≥ l.1 times rated excitation current, and the over excitation acts, the
program will automatically reduces UG, until IL≤1.1 times rated excitation current.
◆ Under-excitation restriction judgment
The PQ action curve of under-excitation restriction is determined upon the static,
stable restriction of different active power of the generator and heat generation
conditions at the generator end. When the generator runs with phase advance and
outputs certain active power P, for the purpose of maintaining static, stable operation,
the excitation current shall be prevented from being reduced below the value required
by the stable operation. Namely, the phase advance reactive Qc output by the
generator shall be restricted within the curve.
Based on the actual active power, the maximum allowable phase advance
reactive power corresponding to PQ characteristics curve is calculated. If the actual
phase advance reactive power is less than the allowable phase advance reactive
power, the under-excitation restriction sign shall be given within the shortest time
(0.06s delayed). In this way, the under-excitation control program is driven, to restrict
the phase advance reactive power to the allowable value.
The increased given value for the under-excitation restriction action shall not
make the output of the auto PID exceed the under-excitation restriction value.
Under-excitation restriction: when the generator is connected to the power
network, the reactive power corresponding to the current active power in the
under-excitation restriction PQ curve is taken as the object value; when the current
reactive power is the feedback quantity, the Pi is calculated; when the output is more
than the automatic PID output, it shall serve as the actual excitation control output.
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When the reactive power experiences abrupt change, the restriction action is rapid
and stable. The under-excitation PI adjustment restriction is provided with the
additional feedback of the excitation current. When the reactive power experiences
abrupt change, the stability of under-excitation PI adjustment restriction is enhanced.
Both P and Q take the apparent power as the per-unit reference value.
The "reactive power" value when the “under-excitation setting Q0” is equal to “0
active power”.
The "active power" value when the “under-excitation setting Q0” is equal to “0
reactive power”.
The “under-excitation restriction flexible feedback factor” is the flexble feedback
factor in under-excitation PI, which is reduced by 100 times in value.
The “under-excitation integral adjustment time” is the integral time constant in
under-excitation PI, whose unit is ms.
The “under-excitation magnification factor” is the steady state magnification factor
KDL in under-excitation PI.
The “current flexible feedback time constant” is the recovery time constant Tr of
excitation current.
Transfer function of under-excitation restriction PI adjustment:
K DL 
1  T DS
TrS
 [Q '' Q ']  K DI 
 IL
1  10T DS
1  TrS
Where: KDL is the steady state magnification factor
TD is the integral time constant
Q″ is the reactive power of the set broken line of the under-excitation
restriction value corresponding to the current active power, and
Q′ is the current actual reactive power.
KDI is the flexible feedback factor, with its range of 0~100%
Tr is the recovery time constant of the excitation current
IL is the excitation voltage or current, with its range of 0~100% of the
per-unit value;
◆ Under excitation restriction
When the generator is connected to the power network, the current reactive
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power is not more than the reactive power corresponding to the current active power
in the “under-excitation restriction PQ curve”, and the automatic output of the PID is
restricted and increased (UG increased).
The increased given value for the low excitation restriction action shall not make
the output of the auto PID exceed the under-excitation restriction value.
Under the mode the excitation is still under the control of the main adjustment
channel, with stable and reliably action. Under the operating condition in which the
reduction in the reactive power is slowed down by the greatly reduced given UREF or
system voltage, the restriction function is reliable, stable.
◆ No-load over-voltage protection
When the generator is not connected to the power network and operates under
the auto mode, and the generator terminal voltage exceeds the restriction protection
value, the “no-load over voltage protection” will not make time delay action.
When the no-load over voltage protection acts, the excitation regulator will
perform the inversion de-excitation, and reset all given values. At the same time, the
“de-excitation switch” relay acts, the de-excitation switch is tripped, and the power
circuit is cut off.
◆ Phase sequence error
After receiving the synchronous pulse, AVR will detect the sequence of the
synchronous pulse. If the sequence is correct, the “phase sequence error” sign will not
act; if the sequence is incorrect, the “phase sequence error” sign will act. When
detecting the pulse, the AVR has certain fault-tolerant capacity, and is able to
eliminate the contingent circumstance with 2 pulses lost continuously.
When these two conditions, i.e. “phase sequence error” and “not connected to
power network”, are met synchronously, the excitation regulator will lock out the pulse
input, thus achieving the purpose of protecting the generating set.
◆ LPT breakage and YPT breakage
When the voltage of either “LPT” or “YPT” is lower than 10% of the rated voltage
of the other, the breakage signal is sent out. When the breakage signal is sent out, the
excitation regulator will operate with the bigger one as the feedback voltage, and
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meanwhile, all restriction protection or adjustment functions in related to power will
withdraw their operation.
3.2.4. Excitation monitoring unit
HMI is short for Human Machine Interface. In terms of generalized definition, HMI
refers to “one interface used to communicate, deliver and receive information
between the user and machine.”
AVR channel shares one HMI, through which AVR completes the data display,
parameter modification and adjustment, and HMI is also the current development
direction of the modern automated equipment.
HMI display unit may select 256 gray scale or 64K color display of 5.7 inch, 8 inch,
10.4 inch or greater size, which is controlled by the precision touch screen or buttons.
The standard ModBusRTU protocol is adopted for communication with the
excitation regulator, and the interface is compiled with EV5000 configuration software,
for selection and replacement.
Each touch screen interface has one taskbar at its left lower part, which is able to
change the menu display and switch the displayed windows in a rapid way. The
taskbar generally has two work buttons, i.e. menu and taskbar. By clicking the menu
button, on the left of the screen may appear the window containing the buttons for
entering each function window, and the function buttons contained therein include
about, A channel, B channel, double channels, control parameter, measurement
correction, test command and safety grade. The relevant display interface is entered
by clicking function buttons. The taskbar primarily controls the display of the whole
taskbar.
Performance parameters of HMI unit
 Display of 5.7 inch, 8 inch, 10.4 inch or greater size;
 256 gray-scale or 64K color display; controlled by precision touch screen or
buttons;
 Internal communication interface: standard ModBusRTU protocol adopted for
communication with AVR;
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 Interface programming: the EV5000 configuration software is applied for
interface programming, facilitating selection and replacement;
 2 high speed serial port;
 The
serial
port
supports
the
communication
and
connection
with
RS232/RS485/RS422;
 One printer port;
 200MHz RSIC processor;
 21～28V DC working voltage and working current MAX=400mA/24V DC；
 Protection level is IP65;
 Complying with EN50081-2 and EN50082-2 standard;
 Complying with FFC Class A compatibility standard;
The following photo shows the touch screen:
The HMI completes such work as data display, parameter modification and
adjustment. The primary functions of the interface are described as follows:
Data display function
The data display is the primary and basic function of HMI. HMI displays both
single channel information and double channel data.
The analog quantity and switch quantity of the data display include three parts, i.e.
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A channel, B channel and double channels.
A channel displays analog quantity and switch quantity of A channel.
Double channels display analog quantity and switch quantity of these two
channels.
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The respective window can be entered by clicking A channel, B channel and
double channels in the menu, in which the analog quantity and switch quantity of the
regulator are shown. The information displayed in both A channel and B channel is
also shown in double channels. At the lower part of 3 display interfaces there are
function buttons for realizing the switching among these three display interfaces. The
buttons of “previous page” and “next page” at the lower part of the double-channel
display interface are utilized to realize the switching between analog quantity display
interface and switch quantity display interface.
The basic contents of the displayed information are introduced as below. As the
double channels include all information as shown in A channel and B channel, the
contents displayed in the double channels are only described.
Analog quantity
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All analog quantity displayed is as follows:
The following table shows the meaning and scope of the
parameters:
ID
Symbol
Meaning
number
00
Typical
Scope
value
CWYGZ
Network voltage tracing
0
ks
1 or 0
switch
CZCKG
Master/slave switch
0
1 or 0
02
CTJKG
Auto shut-down switch
0
1 or 0
03
CVFKG
VF switch
0
1 or 0
04
CVFXZ
VF restriction value
110
95～120
05
CVFSXF
Low frequency failure
4750
4200～6000
action
CDPBH
Low frequency
0 not
input;
01
06
Remar
1 input
42～
60HZ
4500
4700～4200
protection
07
CKZXF
No-load output
12000
16000～8000
restriction
08
CFXXF
Minimum output
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12000
16000～3000
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restriction after network
connection
09
CQLBS
Force excitation multiple
180
250～130
10
CQLSJ
Force excitation time
20
30～10
11
CQLXF
Force excitation output
18000
秒
20000～12000
restriction
12
CKZIL
No-load rated IL
4000
6000～1000
13
CGYGD
No-load over-voltage
13000
15000～9000
protection
14
CKZJY
Step size
1000
2000～100
15
CTCFX
Difference adjustment
1
1 or 0
direction
Positiv
e or
negati
ve
16
CTCXS
Difference adjustment
0
1500～0
coefficient
17
CZDGD
Auto UG set value
10000
12000～4000
18
CRQKG
Auto flexible start-up
0
1 or 0
3000
9500～2000
10000
12000～8000
140
600～10
秒
140
600～10
秒
1 input
switch
19
CRQQD
Initial given value of auto
flexible start-up
20
CRQZD
Object given value of
auto flexible start-up
21
CRQBC
Holding time of auto
flexible start-up
22
CRQSD
Increasing time of auto
flexible start-up
23
CZDKP
Auto Kp
12
60～8
24
CQJF
De-integral
1
1 or 0
1 input
25
CQWF
De-differential
1
1 or 0
1 input
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26
CZDTI
Auto integral time
1000
10000～100
Ms
27
CZDTD
Auto differential time
200
1000～50
Ms
28
CZDKI
Auto integral factor
8000
15000～1000
29
CZDKD
Auto differential factor
200
1000～10
30
CZDYFK
Auto current hard
0
2000～0
feedback coefficient
31
CSDGD
Manual Ig set value
1000
2500～100
32
CSDKI
Manual integral
100
1000～0
3
20～1
1
1 or 0
1 input
1
1 or 0
1 input
8500
10000～3000
9500
12000～4000
3
20～1
100
1000～0
0
2000～0
8000
15000～0
Ms
adjustment time
33
CSDKP
Manual magnification
coefficient
34
CDLKG
Low-excitation
restriction switch
35
CQLKG
Under-excitation
restriction switch
36
CDLQ0
Low excitation setting
Q0
37
CDLP0
Low excitation setting
P0
38
CQLKP
Under-excitation
magnification coefficient
39
CQLKI
Under-excitation manual
Ms
integral adjustment time
40
CQLRKP
Under-excitation flexible
feedback coefficient
41
CQLRTW
Under-excitation flexible
毫秒
feedback recovery time
42
CHGFS
Constant power mode
0
5～0
43
CHWGGD
Constant reactive power
12000
18000～8000
(Var) value
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CHGLGD
Constant power factor
8500
10000～7500
8500
11000～5000
(PF) value
45
CJDQL
Relay force excitation
setting
DC
excitatio
n
46
CJDQJ
Relay forced reduction
11500
13000～9500
setting
DC
excitatio
n
47
CNOKG
White noise switch
0
1 or 0
PSS
signal
48
CNOKP
White noise
0
2000～0
superposition coefficient
49
………
Standby
50
CPSTW1
Recovery time constant
PSS
signal
4000
15000～100
4000
15000～100
4000
15000～100
0
15000～0
Ms
Tw1
51
CPSTW2
Recovery time constant
Tw2
52
CPSTW3
Recovery time constant
Tw3
53
CPSTW4
Recovery time constant
Tw4
54
CPSKS1
PSS enhancement
100
50000～100
55
CPSKS2
Compensation coefficient of
100
5000～100
10
5000～10
0
2500～0
0
2500～0
electrical power integral
56
CPSKS3
Signal composite
coefficient
57
CPST1
Time constant of
compensation link
58
CPST2
Time constant of
compensation link
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CPST3
Time constant of
0
2500～0
0
2500～0
100
30000～100
0
2500～0
0
2500～0
compensation link
60
CPST4
Time constant of
compensation link
61
CPST7
Time constant of
electrical power integral
62
CPST8
Time constant of notch
filter
63
CPST9
Time constant of notch
filter
64
CPSXF
PSS amplitude limit
500
1500～100
65
CPSSP
PSS active input value
4500
9000～500
66
CPSKG1
PSS input switch
1～0～
1 or 0
1 input
1 or 0
1 input
0
67
CPSKG2
PSS input switch
1～0～
0
68
………
Standby
0
60000～0
69
CFWJS
Reset monitoring
0
20000～0
70
CLPKP
LPTA correction
10000
13000～7000
10000
13000～7000
10000
13000～7000
coefficient
71
CYPKP
YPT correction
coefficient
72
CXPKP
XPT correction
coefficient
73
CIFKP
IFA correction coefficient
10000
20000～7000
74
CILKP
IL correction coefficient
10000
20000～6000
The analog quantity is displayed in terms of per-unit value. For example, the
generator voltage 6.3KV corresponds to 100, so when the displayed generator
voltage is 101.20, the actual voltage of the generator is 6.3KV*101.20/100=6.3756KV.
Switch quantity
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The switch quantity is displayed with the graph of the indicator lamp. The displayed
switch quantity is as follows:
The following table shows the meaning and scope of the parameters:
Parameter
name
LPT
breakage
VPT
breakage
Parameter
Parameter meaning
name
Failure of
Excitation PT breakage
initial
excitation
Instrument PT breakage
Phase
Phase sequence error of
sequence
three-phase AC electricity of
error
synchronous generator
V/f restriction
Voltage/frequency restriction
Under
Under-excitation restriction
Relay force
excitation
Parameter meaning
Initial excitation voltage of
the synchronous
generator fails to reach
30% of rated value
Relay
force
excitation
command of DC exciter
Relay forced
Relay forced reduction
reduction
command of DC exciter
Network
Network connection state
connection
of synchronous generator
De-excitation
De-excitation state
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signal
restriction
No-load
No-load minimum output
restriction
restriction
Network
voltage
tracing
Network voltage tracing
input signal
No-load
mistaken
No-load over excitation current
Flexible
Flexible start-up
force
restriction
start-up
command
No-load generator over voltage
Manual
excitation
No-load over
voltage
Over
excitation
restriction
Force
excitation
restriction
Low
excitation
restriction
Frequency
measurement
disappearing
Excitation current exceeding 1.1
Over low excitation current
restriction
power
Constant
power factor
regulation mode
PSS input signal
Constant reactive power
input signal
Constant power factor
input signal
Generator frequency
measurement disappearing
disappearing
disappearing
protection
reactive
force excitation times restriction
Synchronous signal
frequency
Constant
Excitation current exceeding
Synchronism
Low
PSS input
times rated value restriction
Current closed loop
Generator frequency lower than
set value protection
For the above state quantity representing
For the above related state quantity
abnormality and fault, flash indicates yes, and no
indicating operating state of the regulator,
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flash denotes no
on denotes yes, while off indicates no.
Operation instructions for interface
Safety grade
The safety grade operation is described as below:
The safety grade is utilized to set the access jurisdiction of different users, which
can greatly increase the safety of the system. Only possession of high grade code
enables access to high safety grade windows, which greatly increases the safety of
the system.
The system has totally 3 safety grades, i.e. high (grade 2), ordinary (grade 1) and
low (grade 0). The user with high safety grade has access to the windows of higher
safety grade; the user with low safety grade has no such access to the windows of
higher safety grade.
By clicking the safety grade button in the menu to enter the safety grade window,
the code can be modified, to realize the switching among these three said safety
grades: click the safety grade to enter the switching window of safety grade, key into
code and relevant grade code, to modify the safety grade.
The safety grade of about, A channel, B channel, double channels and safety
grade window is low (grade 0).
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Any body has access to them. The grade involves no system operation, and it is
the safety grade under normal operation.
The safety grade of control parameters and test command window is ordinary
(grade 1). The adjustment personnel and power station workers have access to the
windows of such grade, which enables them to modify parameters and issuance
control commands, and generally exerts no deadly effect upon the system.
The safety grade of the measurement correction window is high (grade 2). Only
the adjustment personnel have access to the window, while other personnel are not
allowed to enter such window to modify the parameters. The said grade is the
exclusive grade, which is utilized to adjust and correct the excitation system by the
specialists.
The setting of initial code is as follows: grade-1 code is 8489, and grade-2 code is
****.
Control parameters:
The control parameter menu is described as follows:
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By clicking the control parameters in the menu, the control parameter window can
be entered (notes: at this point, the safety grade shall be grade 1 or higher, otherwise
the access will be refused.)The control parameters displayed are all internal
parameters of the regulator. By clicking the “previous page” and “next page” on the
parameter page, the function of page turning can be realized. The specific definitions
and related attributes of the parameters are shown in the parameter list.
By clicking the parameter value, it can be modified. The specified method is as
follows: by clicking the parameter value screen, the parameter input keyboard will
appear. Input the parameter value, and then click “ENTER”.
Test command
The test command menu is descried as follows:
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There are mainly two test commands, i.e. step up and step down. By clicking the
test command in the menu, the test command window is entered. In the menu, the
user is allowed to select to send commands to either channel at random, or to two
channels at the same time. By clicking the relevant command, one confirmation
window will appear. Click “Confirm” to confirm command sending, and click “Cancel”
to cancel command sending.
Measurement correction
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The measurement correction of the excitation PT, instrument PT, system PT,
stator current PT and excitation current of HWJT-09C excitation regulator is
performed with the software. Their respective measured values can be corrected by
modifying their respective correction factors.
The measurement correction factors are modified in the same way as the
parameter values: by clicking the measurement correction button in the menu,
the measurement correction window is entered (notes: the safety grade of the
measurement correction is grade 2, so only the adjustment personnel with
second safety grade have access to the window); By clicking the factor value,
one value input keyboard will appear, then input modification value and click
“ENTER”.
3.3 Composition of power part
3.3.1. Thyristor power unit
Figure 2 hereunder is the schematic diagram of the primary circuit of the
thyristor power part
Figure 2
1.1 Main circuit
KP1~KP6 in the above figure constitute the thyristor rectifier bridge circuit.
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The three-phase AC power supply is input through QS switch, and the magnitude
of DC output voltage varies with the onstate of the adjustment thyristor of auto
excitation regulator.
1.2 Protection circuit
The rectifier element is poor in bearing over current and over voltage. For the
purpose of safe operation of the element and equipment, some protective
measurement shall be taken.
Over current protection:
The short-circuit protection equipment applies the quick fuse, as shown in
RD1~RD6 in Figure 2. The quick fuse is also equipped with the quick fuse
indicator, which is able to send out the fuse indication and turn on the relevant
signal lamp when the fused mass is melted.
Over voltage protection:
As shown in Figure 2, YMA~YMC and YMR are mainly used to absorb the
over voltage at AC and DC side. R1C1~R6C6 form the over voltage
absorption circuit in the element.
1.3 Signal circuit
a When the switch at the AC or DC side is off, the equipment will give local
indication and send the signal to the central control room and related control
system, to help the force elimination circuit of the excitation regulator act.
b When the fuse is melted, the equipment will give local indication and send
the "melted" signal to the central control room and excitation regulator.
c When the fan is subjected to abnormality, the equipment will send the
abnormal condition of the fan to the central control room.
d The DC side is provided with the DC output voltmeter and DC output
ammeter (local and remote).
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1.4 Fan circuit
When the force air cooling is adopted, the equipment applies one or two sets
of low noise axial flow fan, and the power supply utilized is the AC power supply
from the rectifier equipment through voltage adjustment and isolation and power
supply for the power plant (totally two power sources). The fan in service
generally applies the rectifier power supply. When such power supply suffers any
fault, it will be automatically switched to the power supply for the power plant, to
ensure power supply for the fan.
3.3.2. IGBT power system

Composition and principle of power unit
IGBT element incorporates the power characteristics of double-polarity
transistor and simple control of the field effect, which has been widely applied in
the industrial and national defense field since 1990s. The application of IGBT
element in the excitation field may simplify the power part, and also eliminate
some disadvantages of the controllable rectification mode of the SCR transistor.
Both economic nature and reliability of the system are greatly enhanced.
The power unit is mainly composed of two parts, i.e. rectifier equipment and
power switch. The former converts the AC excitation power supply into DC power
supply, while the latter is controlled by the regulator. The magnitude of the
excitation current can be controlled by adjusting the closing time of the power
switch. In other words, the excitation input power of the generator can be
controlled by adjusting the onstate time of the power tube. The schematic
diagram is shown in Figure 3
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Figure 3
ABC in Figure 3 is the three-phase excitation power supply, and LQ is the
rotor winding. When QS is closed, the three-phase AC excitation power supply
undergoes the three-phase rectification through D1~D6, to produce DC voltage
Ue; when the IGBT is switched on, Ue is added to the winding LQ, to increase the
current in LQ; when IGBT is switched off, the current continues to be supplied to
LQ through D7 onstate.
The DC voltage after rectification is Ue, and onstate time of IGBT is Ton.
When the IGBT is switched on, Ue is added to both ends of the rotor. Closing time
of the IGBT is Toff. When the IGBT is switched off, the rotor voltage is equal to the
voltage drop of the continuous current diode D7, which is equal to zero when
being ignored. The excitation voltage waveform of the excitation winding is shown
in Figure 4.
Figure 4
The figure shows that the average value of the excitation voltage is:
U LL  U e 
Ton
Ton
 Ue  D ， D 
Ton  Toff
Ton  Toff is duty ratio.
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This shows that when D is changed based on such factors as generator
terminal voltage, rotor current or reactive load, the duty ratio of IGBT drive square
wave is altered. Namely, the voltage at both ends of the excitation winding can be
changed to achieve the purpose of adjusting the output voltage and reactive
power of the generator.
 IGBT drive
Large power IGBT switch excitation equipment applies the exclusive drive
module for control, whose schematic diagram is shown in Figure 5 as follows:
Figure 5
过流保护 Over current protection
VCC and VEE are power sources, and the opto-coupler isolates the control
circuit and IGBT. Dz is the stabilized voltage tube, which provides the reverse bias
when IGBT is switched off. When there is the onstate control signal, the
opto-coupler OP1 is switched on, which switches on the output triode T1 through
the magnifier A and switches off T2. VCC is output to the grid electrode G of IGBT
through T1, to provide IGBT grid electrode with positive bias and switch on IGBT.
When there is no onstate control signal, OP1 is not switched on, and the
magnifier A switches off T1 while switches on T2. The voltage in the stabilized
tube Dz subjects IGBT grid electrode voltage to reverse bias through T2, to
ensure reliable closing of IGBT. When IGBT is subjected to over current, the over
current protection acts, and the magnifier A is closed, to subject the IGBT grid
electrode voltage to reverse bias for protection.
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 Comparison between self shunt switch excitation and thyristor exciation
of IGBT
a Simple drive of switch excitation
In the thyristor excitation, six sets of drive circuits and pulse transformers
shall be provided; however, IGBT just needs to provide one drive signal. In
addition, as IGBT is the voltage control element, it can, with small drive power,
easily utilize the opto-coupler to realize high voltage isolation.
b Simple synchronization of IGBT switch excitation
In the thyristor excitation system, the output voltage is directly correlated with
the control angle α of the thyristor. Furthermore, as the AC synchronous signal
input is subjected to serious distorsion, for the purpose of obtaining accurate
synchronous zero passage trigger signal, the AC synchronous signal shall
undergo more complex treatment. In the IGBT excitation system, the output is
related to the onstate duty ratio D of IGBT, and the relative time relation between
the duty ratio D and AC power supply exerts no great effect upon the equipment
output, so no complex synchronous circuit requires to be designed.
c Simple control of IGBT switch excitation
In the thyristor excitation, the relation between input & output and control
angle α is as follows: ULL=1.35UIN×COSα. For the purpose of improving the
linearity and stability of the system, the generation of the thyristor trigger pulse
requires cosine compensation, thus adding to the complexity of system control. In
the IGBT switch excitation, the relation between input & output and control angle
α is as follows: ULL=1.35UIN×D. Therefore, the system is possessed of fine
linearity and stability, thus reducing the control complexity.
d The switch excitation may greatly reduce the capacity of the excitation
transformer, thus decreasing cost.
In the thyristor excitation, the continuous current of the rotor winding goes
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through the thyristor and excitation transformer coil. While in the IGBT switch
excitation, the continuous current of the rotor winding only goes through the diode
but the excitation transformer coil, so that the capacity of the excitation
transformer can be reduced by over 30%.
3.4 De-excitation and over voltage protection equipment
3.4.1. Composition of de-excitation and over voltage protection
system
The de-excitation and rotor over voltage protection equipment includes
several kinds, i.e. the non-linear de-excitation and rotor over voltage protection
equipment made up of zinc oxide voltage dependent resistor components, linear
de-excitation and rotor over voltage protection equipment composed of the linear
resistor and contact-free de-excitation and rotor over voltage protection system
realized by the electrical elements.
3.4.2. Operational principle of de-excitation and rotor over voltage
protection equipment
 Non-linear de-excitation and rotor over voltage protection equipment
The wiring diagram of the de-excitation and rotor over voltage protection
equipment is shown in Figure 6. FMK is the main contact of the de-excitation
switch. The non inductive resistor (R) and voltage dependent resistor (YMR) form
the voltage dependent resistor components, which are directly connected to both
ends of the rotor. The other group of components at the excitation power supply
side serves to protect the power supply.
The rated rotor voltage U fN 0.25×U 10mA ， U 10mA is generally adopted as
the breakover voltage U 10mA =U 10mA （R 1 ）+···+U 10mA （R n ) of each series of
voltage dependent resistor components.
Under normal operation, as the rotor voltage is relatively low, and the current
going through the voltage dependent resistor is leakage current, which is several
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ten or hundred mA, therefore exerting no any effect on the operating condition of
the rotor. Furthermore, the aging speed is also extremely low.
Once the over voltage occurs, the voltage dependent resistor may
immediately operate within the large current area, and the over voltage is
restricted and absorbed. The voltage dependent resistor is in parallel connected
to both ends of the rotor, and the zinc oxide resistor chip has no any time delay
response, without matching problem in respect of the voltage-second
characteristics, thus being extremely reliable in protecting the rotor.
FMK
R
YMR
YMR
R
YMR
F
L
Q
FMK
Figure 6 Wiring diagram of de-excitation and over voltage protection
When the de-excitation is required, FMK is commanded for breakage. As
FMK can establish voltage and achieve de-excitation in a rapid manner, it rapidly
cut off the link between the rotor and excitation power supply. As the rotor is a
large inductance, the di/dt increases rapidly. When it exceeds the breakover
voltage of the voltage dependent resistor components, the onstate of the voltage
dependent resistor is at the low resistance state. The rotor current is shifted from
FMK to the voltage dependent resistor, to complete current change. The rotor
energy is released through the voltage dependent resistor, to achieve
de-excitation. During the course of de-excitation, the voltage at both ends of the
voltage dependent resistor (namely rotor voltage) is almost a constant value, and
the de-excitation process approaches ideal de-excitation.
The de-excitation process of an example is shown in Figure 7.
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u
100m s
f
Figure 7 Waveform diagram of measured rotor voltage in de-excitation
(S=50MW，I fn =600A)
The figure shows that only several seconds are required from switch
disconnection to complete voltage establishment, and total time for completing
de-excitation is about 400ms.
The external characteristics of any two voltage resistors may be not identical.
In this case, two voltage dependent resistors directly connected in parallel may
absorb different energy under large current. Figure 8 shows that the current
through #1 and #2 resistors is quite different under the same voltage.
U
#1
#2
I
I1
I2
Figure 8 External characteristics of two voltage dependent resistors
When several ten and even hundred voltage dependent resistors are
combined, the problem in respect of even energy is of great significance. At
present, the external characteristics of each voltage dependent resistor can be
acquired through various perfect detection methods, and then input into the
computer. Some groups of voltage dependent resistor components with basically
consistent external characteristics and especially in the large current area, with
slightly different external characteristics, are selected among a large number of
valves. The de-excitation and over voltage protection equipment formed in this
way has over 0.9 even energy coefficient. In addition, HMC series are also
connected in series with non inductive linear resistor and voltage dependent
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resistor components, thus achieve better even current and even energy effect. As
shown in Figure 9, after non inductive resistor is connected in series, its even
current effect becomes more remarkable. Under extreme circumstances, even
though one group of voltage dependent resistor is damaged, the linear resistor in
series connected with such resistor may be quickly burned out, to cut off the
damaged voltage dependent resistor. The linear resistor also has the function of
fuse.
U
#1
#2
IR
I
I1 I2
I1
I2
Figure 9 External characteristics of voltage dependent resistor in series
connected with linear resistor
For the problem in respect of even energy of the de-excitation resistor
(non-linear), we do not recommend the fuse method for the causes as follows:
1）
The linear resistor is superior to the fuse in even energy effect;
2）
When the energy is uneven, the burn-out time of the linear resistor is
longer than that of the fuse, thus avoiding the “cracker effect”.
 Linear de-excitation and rotor over voltage protection equipment
Considering the decentrality of non-linear resistor parameters and restriction
of service life of the non-linear resistor, together with impossibility for the turbine
generating set to realize rapid de-excitation, the turbine generating set and
foreign de-excitation equipment almost applies the linear resistance de-excitation
method, which is basically identical with the wiring method of the non-linear
resistor de-excitation equipment. The de-excitation switch almost utilizes the
auxiliary normally closed joint to connect the linear resistance. Typical wiring of
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the linear resistance de-excitation is shown in Figure 10.
FMK
发电机
G
YMR
F
L
Q
V
Rm
FMK
Figure 10 Wiring diagram of HMC-01 double break linear de-excitation and over
voltage protection
 Contact-free de-excitation and rotor over voltage protection equipment
With development of electric & electronic technologies, a lot of large power, high
voltage withstand new electric & electronic elements, which have been applied to the
main circuit of the excitation. Wuhan Hongshan Electrical Science & Technology Co.,
Ltd, after developing the fresh excitation adjustment equipment based on GTR and
IGBT, now applies the new electric and electronic elements IGBT and IGCT to the
filed of generator de-excitation and rotor over voltage protection, whose composition
is similar to the jumper method widely utilized at early times. Figure 11 and Figure 12
are the schematic diagrams of the new de-excitation equipment.
发电机
YMR
F
L
Q
V
Rm
Figure 11 Wiring diagram of HMC-02 linear de-excitation and over voltage protection
发电机 Generator
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发电机
YMR
YMR
V
F
L
Q
Rm
Figure 12 Wiring diagram of HMC-02 non-linear de-excitation and over voltage
protection
发电机 Generator
3.4.3. Technical specification and common setting calculation
method of de-excitation and rotor over voltage protection
equipment
 Related technical requirements of Technical Specifications for Self Shunt
Static Excitation System of Large Turbine Generator in respect of
de-excitation equipment and rotor over voltage protection:
1) The generator de-excitation shall apply two methods, i.e. inversion and
switch excitation. The de-excitation equipment shall be simple and reliable.
When the de-excitation occurs under force excitation, the over voltage of the
generator shall not exceed 4~6 times rated excitation voltage.
2) When the operating voltage is 80% of the rated value, the de-excitation
switch shall be reliably closed; when the operating voltage is 30%~65% of
the rated value, it shall be reliably opened.
3) The de-excitation resistor shall generally apply the linear resistor, which can
be 2~3 times the hot state value of the magnetic field resistor.
4) The generator rotor over voltage protection equipment shall be simple and
reliable. The action voltage shall be higher than the over voltage when the
de-excitation and asynchronism operate after force excitation, and at the
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same time, lower than 70% ex-factory power frequency voltage withstand
test amplitude of the rotor winding.
 Related technical requirements of Technical Specifications for Static
Rectifier Excitation System of Large- and Medium-sized Turbine
Generator in respect of de-excitation equipment and rotor over voltage
protection:
1) The excitation system shall be equipped with auto de-excitation equipment
and switch. Under any operating condition where the de-excitation is
required (including the case of no-load mistaken force excitation of
generator), the auto de-excitation equipment and switch shall ensure reliable
de-excitation, and the de-excitation time shall be short (or according to the
user’s requirement).
2) The de-excitation equipment adopting the zinc oxide non-linear resistor shall
meet the following requirements:
a．
During de-excitation, the reverse voltage of the excitation winding
shall be generally lower than 30% of the test voltage to ground of the
excitation winding in ex-factory test, or higher than 50% thereof;
b．
Non-linear resistor load rate shall not be more than 60%;
c．Non-linear coefficient of the whole set of non-linear resistor equipment
<0.1;
d．
Under the operating condition where the most severe de-excitation
occurs, the energy dissipation capacity of the non-linear resistor shall not
exceed 80% of its working capacity; at the same time, when 20%
components within the equipment withdraw from their operation, the
requirements of the operating condition where the most severe
de-excitation occurs shall be met;
e．
Under other operating conditions, except when the de-excitation
occurs under internal fault of the generating set or no-load mistaken force
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excitation, two continuous de-excitation is allowed;
f． The service life of the non-linear resistor elements shall not be less than
10 years, which is generally not restricted by the de-excitation times.
-
The magnetic field breaker--non-linear resistor de-excitation system shall
conform to the following requirements:
g．
The minimum setting-off capacity shall not be more than 60% of the
rated excitation current;
h．
The maximum setting-off capacity shall not be less than 300% of the
rated excitation current.
 Calculation method of non-linear de-excitation
Based on the related technical requirements above, the calculation method of the
non-linear de-excitation is as follows:
Test voltage of rotor winding:
Us＝10ULe
Maximum allowable reverse voltage in de-excitation:
Umax ＝0.5 2 US, namely,
U60A of non-linear resistor
Minimum reverse voltage in de-excitation:
Umin=0.3 2 US ，namely, U10mA of
non-linear resistor， and U10mA≥ 2 U2／0.6.
In accordance with U10mA=U60A/KC, (where KC=1.4~1.5 is residual voltage ratio
of de-excitation resistance), the voltage parameters of non-linear resistor are
reasonably selected.
Total energy of the rotor when the generator runs without load:
J0＝(1/2)LI02
Where: L is rotor inductance, L＝RLTdo`；
RL＝(235+75)RLt/(235+t) is the rotor resistance at 75℃;
Tdo`
is
the time constant of the rotor when the generator stator is subjected to
open circuit.
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Maximum de-excitation capacity (no-load mistaken force excitation of generator):
JM＝4J0
The consumed energy in non-linear resistor is generally 70% of total energy, so
its total energy capacity is:
JNR＝0.7JM
Even energy coefficient is chosen as 0.9, and the total energy capacity is:
JN=JNR/0.9
The maximum de-excitation energy capacity shall be ensured in 80% withdrawal,
and the final non-linear resistor energy capacity is:
J=JN/0.8=1.94Tdo’RLI02
 Calculation of linear de-excitation
The linear de-excitation resistance is generally 4~5 times the hot state resistance
of the generator rotor winding, and its rated current is 0.15~2 times of the rated
excitation current of the generator. Therefore:
RM=(４～６)RL(75℃)
IR=(0.15～0.2)ILe
3.4.4. Introduction to high energy zinc oxide voltage dependent
resistor
The zinc oxide voltage dependent resistance has excellent linearity, whose
characteristics can be described with the following formula:
U=KI 
Where: U is voltage of voltage dependent resistor; I is current through voltage
dependent resistor;  is non-linear coefficient, which is generally about 0.01; K is
coefficient of proportionality. The formula shows that when  is smaller, the change of
I exerts less influence upon U, namely, the non-linear characteristics are better. Of the
non-linear elements, the  of carborundum of traditional non-linear elements is about
0.1, while that of zinc oxide is 0.01, one order of magnitude lower than carborundum.
Therefore, the non-linear characteristics of zinc oxide are extremely excellent, almost
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approaching ideal case. Volt-ampere characteristics of zinc oxide are shown in Figure
13.
It can be divided into two areas: I is small current area, and II is large current area. In
the small current area, the current through the voltage dependent resistor is small;
while in the large current area, although the voltage is subjected to small change, the
current ranges from mA to several hundred A.
U
I
Figure 13 Volt-ampere characteristics of voltage dependent resistor
By means of its non-linear characteristics, the voltage dependent resistor is
connected in parallel to both ends of the protected object, as shown in Figure 14.
Under normal operation, the voltage dependent resistor works in the small current
area, and the current through the voltage dependent resistor is only several hundred
mA. In this way, the energy is not consumed, nor is the operating condition of the
protected object affected. Once over voltage occurs, it immediately comes to the
large current area without going through the time delay voltage dependent resistor,
the over voltage is restricted and absorbed, and the protected object is made safe.
Z
Figure 14 Wiring diagram of voltage dependent voltage and protected voltage
High energy voltage dependent resistor is a kind of zinc oxide resistors, which is
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mainly characterized by large energy capacity and quick response speed. The
nominal energy capacity of signal resistor is 20KJ, its breakover voltage U10mA is
generally 450~600V, and its response delay is approx. 100µs. Another indicator for
measuring
the
voltage
dependent
resistor
is
residual
voltage
ratio
KC=U100mA/U10mA. For the high energy voltage dependent resistor, KC is less
than 1.5.
China has been involved in the production of the high energy voltage dependent
resistor for nearly 20 years, and recently introduced several production lines, thus
greatly enhancing the production capacity and valve quality. The parameters of the
valve are relatively stable and consistent. In this way, the equipment quality is reliably
ensured.
3.5.
Independent
excitation
current
regulation
channel
(optional)
The independent excitation current adjustment channel is the non-standard
configuration. If such configuration is selected, it shall be indicated in the technical
agreement.
The excitation current adjustment channel with totally complete hardware and
software takes the Intel Corporation’s signal resistor as control core, and through the
adjustment by the excitation current (voltage) closed loop PID (PI), realizes the
operating mode of the generator constant excitation current (voltage).
When over one “auto” channel is in normal condition, the independent
measurement excitation voltage and current realizes the trigger angle tracing with the
excitation current as the feedback current, without outputting trigger pulse; when two
“auto” channels suffer fault or withdraw from their operation manually, the “excitation
current adjustment channel” withdraws from the tracing state, inputs the trigger pulse,
and thus realizes the operating mode of the generator constant excitation current
(voltage). Its main characteristics are as follows:
 Box type structure, with fine EMC (electro-magnetic compatibility)
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performance;
 Full digital micro-computer system, with totally independent hardware and
software;
 Digital cosine phase shift technology adopted, ensuring linear control of
the excitation system;
 CPU+MPU structure, with simple, reliable system;
 The input & output channels are completely electrically isolated, thus
possessing better anti-interference performance;
 Operating parameters are online displayed and set.
3.6 PLC Operation and control system (option)
PLC operation & control system is the non-standard configuration. If such
configuration is selected, it shall be indicated in the technical agreement.
In accordance with the user’s requirements, the system can replace the
traditional relay logical operation control circuit with PLC (programmable controller).
Based on the operating circuits required by the different excitation system, PLC of
different node capacity is adopted.
PLC not only realizes the logical programming of the excitation control system,
but also achieves the local direct-viewing logo board (made up of light bars) display of
working state, system abnormality and system fault of the excitation system.
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Part IV Operation Instructions for Control Equipment
In the operation instructions for the control system described in this part,
HWJT-09C micro-computer excitation control equipment completes electricity
collection like the generator and excitation input and output and output of control
switch quantity, and through the conversion and software control computation,
outputs state signals and control signals of power cabinet. For the switch type
excitation equipment, the regulator outputs the PWM square wave with variable duty
ratio; for the thyristor excitation equipment, the regulator outputs the thyristor trigger
angle. The control part of the excitation regulation & control system is generally
composed of the signal cabinet, which is referred to as control cabinet, and whose
output is utilized to control power output.
4.1 Introduction to system
HWJT-09C microcomputer excitation control cabinet is composed of two DSP
excitation regulation units, on pulse power amplifier power supply and one industrial
HMI.
Regulator and power amplifier power supply
Each regulator possesses independent electricity quantity measurement and
switch quantity input and output unit. The power of each regulator is supplied by one
power supply module. The module is provided by the external filtering rectifier circuit
especially designed, into which one DC power source for power plant, one AC power
source for power plant and one three-phase AC power source provided by the
excitation transformer can be input.
The power supply has one ship type switch, which is located on the regulator
panel; if the switch is in the off state, the equipment will lose the operating power, and
the regulator will completely cease its operation.
If necessary, the control cabinet is also equipped with two pulse power amplifier
power sources, to supply operating power to the exclusive drive module of IGBT or
thyristor pulse power amplifier. The operating power is also supplied by the filtering
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rectifier circuit or the switch of the regulator control cabinet.
4.2. Instructions of regulator panel
HWJT-09C microcomputer excitation regulator takes the 32-digit DSP control
chip by TI Corporation and the peripheral element of the programmable controller as
the core, supported by the integrated circuit composed of the serial controller popular
in industry. Through the serial communication circuit, the regulator exchanges data
with the main control CUP at 19.2K, and the main control CUP forms the double CUP
system together with system control CPU, thus greatly enhancing the system
reliability and stability.
The chapter primarily introduces the operating method and the functions of the
buttons and indicator lamps on the panel.
HWJT-09C 系列微机励磁调节器 HWJT-09C series micro-computer excitation regulator
电源 Power supply
并网 Network connection
异常 Abnormality
运行 Operation
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空载 No-load
增磁 Magnetism enhancing
减磁 Magnetism reducing
手动 Manual
灭磁 De-excitation
切脉冲 Pulse pruning
The indicator lamps on the panel are described as follows:
a> Power indicator lamp: used to indicate normal operation of the switch power.
b> Network connection indicator lamp: used to indicate location of the main switch of
the generator.
c> PSS indicator lamp: used to indicate operating state of regulator in PSS.
d> Constant reactive power indicator lamp: used to indicate operating state of the
regulator with constant reactive power.
e> Operating indicator lamp: used to indicate normal operation of the regulator.
f> Master/slave indicator lamp: used to indicate that the current regulator is the
leading regulator.
g> Communication indicator lamp: used to indicate normal communication when
flashing.
h> Constant PF indicator lamp: used to indicate operating state of the regulator with
constant power factor.
i> Manual indicator lamp: used to indicate manual operating state of the regulator.
j> Force elimination indicator lamp: used to indicate restricted force excitation output
of the regulator.
k> Abnormality indicator lamp: used to indicate that the regulator is subjected to
abnormality, to attract the attention of the operator.
l> De-excitation indicator lamp: used to indicate that the regulator is in the inversion
de-excitation state; at this point, the de-excitation switch is off, or the inversion switch
in the regulator is on.
m> Over excitation indicator lamp: used to indicate that the excitation current output
of the regulator is over great, which exceeds 1.1 times rated value.
n> Fault indicator lamp: used to warn the operator that the regulator is being in the
faulty operating state. At this point, timely treatment is required.
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The buttons and switches on the panel are described as follows:
a>
Power supply switch: used to connect or disconnect working power of the
regulator.
b>
“Magnetism enhancing” button: used to increase the given voltage of the
regulator generator (Ug or Ig).
c>
“Magnetism reducing” button: used to decrease the given voltage of the
regulator generator (Ug or Ig).
d>
“Manual” button ： used to convert the regulator into manual operation
(constant excitation current).
e>
“De-excitation” button：The inversion de-excitation of the regulator acts,
and the control angle is set at 129.6°.
f>
“Pulse cutting” button: when the pulse switch of one regulator is at the
position of “cutting”, the regulator outputs no pulse signal, but another regulator in
parallel connected thereto is not affected. If the pulse switches of these two regulators
are cut off, the whole excitation system will output no excitation current; however, the
equipment still carries electricity, and the measurement, computation and protection
units of the regulator are still working as usual. Once the pulse switches are again
closed, the regulator will output the control signal in terms of the current calculation
results.
Safety prompt: when the pulse switch is operated, close attention shall be given
to the output magnitude of the operated regulator, namely, its duty ratio or trigger
angle of the thyristor.
4.3 Operation instructions for HMI
HWJT-09C excitation regulator, through the excitation monitoring unit, realizes
the background functions of the excitation regulation system like human machine
interface, test and adjustment.
After being connected to the power supply, the regulator is automatically started,
and the HWJT-09C excitation display system is automatically driven.
See “3.2.4 Excitation monitoring unit” for detailed operations.
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Part V Ex-factory Test and Site Adjustment
5.1 Ex-factory test
In accordance with the drawing provided together with the equipment, first check
whether the wiring, terminal wiring and power wiring are correct or not, and whether
the electrical and mechanical performance of the installed power elements (electric
capacity of conductor, insulation, temperature, corrosion prevention, mechanical
strength, etc.) are qualified or not. At the same time, the said drawing is reviewed. It is
ensured that the delivered equipment and its drawing attached are complete and
consistent, and the ex-factory report is correctly prepared.
User’s preparations
The following preparations shall be carried out by the user:
1. All wires and cables are laid and connected to the excitation cabinet, and then
checked in accordance with the wiring diagram. The voltage transformer, current
transformer and protective circuit are included;
2. AC and DC power sources are connected to the control equipment, and then
the switch is closed;
3. If the generator test and some primary tests are required, the temporary power
source for the excitation transformer is prepared, and then the switch is closed;
4. Other devices, like monitoring & protection equipment, sub-station/cable,
speed regulator, original motor, generator and auxiliary equipment, shall be prepared
before the excitation adjustment;
5. Safety shield is prepared.
Installation inspection
1. Basic conditions
1) AC input of the rectifier equipment shall be removed;
2) DC output of the rectifier equipment shall be removed;
3) All other connections with the power plant shall be completed;
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4) All input power switches shall be cut off;
5) All power switches of internal equipment shall be cut off;
6) All inserters and formworks shall be removed from the framework.
2. Mechanical inspection
Check whether all devices are damaged during transportation and installation. If
any defect is detected, the record shall be made, and the after-sales service
department is in time informed thereof for treatment. Following this, the next work can
be proceeded with.
3. Cable inspection
It shall be ensured that all cables are correctly connected, and consistent with the
relevant installation drawing.
Note: the twisted-pair cables shall be utilized in strict accordance with the drawing;
the power and signal cables shall be isolated and shielded, and the shield layer shall
be correctly used. Special attention shall be paid to the phase sequence of PT, CT,
synchronous power supply and trigger pulse.
1) Check whether the twisted-pair cables are utilized or not;
2) Check whether the power and signal cables are isolated or not;
3) Check whether the shield layer is correctly treated and grounded or not;
4) Check whether the phase sequence of PT, CT, synchronous power and trigger
pulse is correct or not.
4. Grounding inspection
The grounding is of crucial significance. The cabinet shall be provided with the
grounding terminal, and the following places shall be supplied with convenient
grounding points.
· The equipment cabinet rack is grounded.
· The equipment is grounded with zero potential.
· Digital shield—shielding point connected with the digital signal cable
· Analog shield—shielding point connected with the analog signal cable
Note: during test these terminals can be temporarily connected, but at last they
shall be separately grounded as above.
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The above inspection shall be completed before the following tests are
proceeded with.
By means of added test power supply, the circuit units of the regulator undergo
tests and calibration, as well as routine anti-interference test. The test wiring is as
follows:
The PT voltage, CT current and synchronous voltage of the generator is sent to
the regulator through the analog test platform, which is then connected to the relevant
power unit or power cabinet for comprehensive analog test and aging test.
5.1.1. Inspection and calibration of display state

After the regulator is connected to the power supply, observe the
display situation of the power indicator lamp and 8-digit luminous digital
tube; when the display is normal, adjust the regulator used to simulating
PT voltage to 100V, and calibrate UF display value to 100.00.

Separately push the button for magnetism enhancing and the
button for magnetism reducing, and observe the change range of Ug; the
normal range is from 0 to 120.00.

When Ug<UF ～ Ug>UF, the duty ratio of the excitation system K
(displayed as H) ranges from -100% to +100%, and the trigger angle α of
the thyristor excitation system varies between 129.6 and 19.2.

The displayed frequency shall be 50.000HZ.

When the CT current of the generator input into the regulator is
changed, IF display will be altered accordingly. The correction coefficient
is adjusted through the keyboard, to make the displayed value consistent
with the actual converting value.

The analog current transformer outputs the excitation current signal;
the correction coefficient is adjusted through the keyboard, to make the
displayed value consistent with the actual converting value.

Change the phase of PT voltage and CT current input into the
regulator, simulate the change in reactive power, and observe and
calibrate the displayed readings.
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5.1.2. Signal and switch quantity inspection
Short connect switch quantity with peripheral input points on the terminal, and
observe changes in the relevant indicator lamp or HMI display.
 Short connect fan or temperature detection joint: when the power
supply of the fan is removed, the indicator lamp shall be off.
 Short connect oil switch joint: the network connection indicator lamp
shall be off, and no-load state is displayed.
 Short connect start-up joint: when PT voltage of the generator is less
than 30V, Ug shall be set to the relevant set value.
 Short connect de-excitation joint: reset Ug, set K of IGBT excitation system to
-100%, and set the trigger angle α of the thyristor excitation system to
inversion angle 129.6.
 Short connect manual joint: the manual lamp is on, and manual adjustment
state is entered; Kc of IGBT excitation system is equal to Ks, and α of the
thyristor excitation system is equal to 2α.
 Auto adjust state: Kc of IGBT excitation system is equal to Ks, and α of
the thyristor excitation system is equal to 2α.
5.1.3. Trigger pulse measurement
For the IGBT excitation system, the oscilloscope is utilized to observe the output
pulse waveform of the regulator. When the pulse increases by 2~7μs, the frequency
shall be consistent with the design, and the pulse duty ratio shall be in agreement with
the display. It is single pulse.
For the thyristor excitation system, the oscilloscope is utilized to observe the
output pulse waveform of the regulator. The pulse height varies with the thyristor,
which is generally 1.5~7V, the pulse width is 1ms (50Hz) or 0.1ms (500Hz), the
double pulse interval is 60, and the trigger angle is consistent with the display.
5.1.4. Small load waveform observation
Disconnect the output switch, add AC or DC power source, and check whether
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the electrical elements (e.g. power element, diode, resistor, capacitor, voltage
dependent resistor, switch, etc.) are normal or not, and whether they are subjected to
any abnormal heating, electrical leakage or breakdown.
For the IGBT excitation system, adjust the positive and reverse group pulse to be
smaller duty ratio output state (if the analog PT voltage suffers greater fluctuation, the
manual channel can be operated), apply the resistance load to the power DC output
side (if necessary, connected load in series of resistance and inductance is applied),
close the output switch, and observe whether the load waveform is consistent with the
control waveform. The on-off over voltage peak shall be less than 120% (inductive
load is less than 150%).
For the thyristor excitation system, adjust the control pulse of the regulator to be
smaller output state (if the analog PT voltage suffers greater fluctuation, the manual
channel can be operated), apply the resistance load to the power DC output side (if
necessary, connected load in series of resistance and inductance is applied), close
the output switch, and observe whether the load waveform is normal or not, and
whether 6 wave fronts are distributed evenly. In addition, check whether the
magnetism enhancing waveform or magnetism reducing waveform varies evenly or
not, without jump.
5.1.5. Large current test
When the large current test is carried out, the complete record shall be made of temperature
increase of various parts of the excitation equipment.
5.1.6. Anti-interference test
The large power interphone is utilized to conduct radio frequency interference to
the switch power, main control unit and display unit, and these units shall be in normal
condition, working parameters subjected to no change, and output waveform normal.
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5.2 Site adjustment
5.2.1. Site wiring inspection
The site wiring is completed by the user in accordance with the drawing provided
by our company. If the drawing is subject to any change, such change shall be
executed in a correct way.
1. Check main circuit wiring
First, learn about the related problems in respect of the matching generating
set of the equipment, such as the excitation mode, operating mode, power
magnitude and standby excitation or not. Then, check whether the main circuit
wiring of the excitation equipment is in consistence with the drawing or not. The
“consistence" means that the wiring is in any respect consistent with the drawing.
With respect to AC excitation mode, carefully check selection position and phase
connection of synchronous point, to achieve accurate, reliable synchronous
signal.
After the main circuit wiring is checked, clearly understand the connection
relationship among various parts: input source, output terminal, intermediate
transferring location, primary circuit voltage, primary circuit current and heat
generation. The handling of possible abnormality like over voltage, over current
and over heat shall be taken into account.
2. Check power supply circuit
The power of HWJT-09C regulator is generally supplied by two power
sources, i.e. AC power source and DC power source. The former comes from the
AC power supply for the power plant, AC exciter terminal or secondary side of the
excitation transformer; the latter is from the DC system for the power plant. First
confirm the type and amplitude of the power supply, and check the power supply
wiring, fuse, quick fuse and breaker; when they are all normal, the power supply
can be connected.
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In principle, the excitation equipment, when losing either power source, can
not operate normally (in fact, if the DC power source is lost, the DC operation
circuit of the equipment will not act).
Correct main circuit wiring and power supply circuit wiring is the fundamental
condition of the operation of the excitation regulator, and at the same time, is
related to the personal and equipment safety, so it shall be serious treated.
3. Check switch quantity signal
After correct power supply is confirmed, the equipment can be connected to
the power supply to test its basic operations. The local operation has been
checked in the ex-factory test; the remote operation shall be subjected to actual
operation
inspection
on
the
site,
which
includes
remote
magnetism
enhancing/reducing and various switches, breakers, relays and contactors of
remote closing/opening equipment. During the operation, close attention shall be
paid to whether the location indication signal of various switches is correct or not.
The operation circuit of the excitation equipment also includes some switch
quantity signals from and into the remote equipment, and there are more such
switch quantity signals in the hydropower generating unit, such as start-up,
shut-down and rotating speed signal. They are of great significance to the normal
operation of the excitation equipment, which shall undergo complete simulation
before being subjected to the tests. In the self shunt excitation mode, the switch
quantity signal transmitted between the power cabinet and the regulator
determines whether the regulator eliminates force excitation, and the logical
relation
thereof
is
relatively
complex,
which
shall
be
carefully
and
comprehensively judged.
5.2.2. Static test of regulator
The performance inspection of the regulator connected to the power supply is
generally referred to as the site static test (the subsequent operation test of the
closed loop of the regulator is called site dynamic test). In addition to repeating the
main items of the ex-factory test, the static test shall involve some specific adjustment
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of HWJT-09C excitation equipment based on different excitation systems. Four cases
are roughly involved:
1. DC excitation system:
The excitation power supply comes from the output of the DC exciter. The
power input power supply can be simulated through the DC 220 system for power
plant, and based on the actual situation of the working power supply, the power
circuit undergoes special adjustment. If the actual voltage is lower than 220V, the
power elements undergo test in the 220V system. The voltage withstand grade of
the power parts can meet the requirements, but the current shall be prevented
from exceeding restriction value.
Under the parallel operation of double control units, the synchronous signal of
these two units shall be tested, to ensure safe parallel operation of double
systems.
2. Three-generator excitation mode
Under three-generator excitation mode, the excitation power of the excitation
equipment is supplied by the pilot exciter. The pilot excite is divided into two kinds,
i.e. permanent magnetism and self excitation. The former requires no excitation
power, thus with higher reliability; the latter requires the self excitation constant
voltage equipment for self excitation. The self excitation constant voltage
equipment is actually small self shunt excitation equipment. Like other self shunt
equipment, the self excitation constant voltage equipment can not operate under
the condition of open loop, so full preparations shall be made for the static test.
For example, during the static test, by means of the simulation of the stochastic
change in the terminal voltage of the pilot exciter, observe whether its reaction is
correct; by use of the simulation of the process of self excitation voltage
establishment, observe whether the synchronous circuit and measurement of the
terminal voltage are stable and correct or not.
The pilot exciter provides the whole generating set with the preliminary
excitation power, whose waveform may be distorted under greater load, thus
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affecting the synchronous circuit of the regulator. Therefore, when the stator
current of the pilot exciter is greater, the waveform of various points in the
synchronous circuit of the regulator shall be carefully measured.
Note: the terminal voltage referred to here means the control object of the
excitation constant voltage equipment, and also the stator voltage of the pilot
exciter. In the case of the self shunt excitation mode of the generator, the terminal
voltage mentioned refers to the stator voltage of the generator When the dynamic
test is carried out, the stator winding of the pilot exciter provides the excitation
regulator with the excitation power, and the power element of the excitation
regulator provides the rotor winding of the main exciter with the excitation current.
When the conditions permit sometimes, the power output is connected to dummy
load, to ensure test safety, and at this point, the generator operates depending on
the standby excitation.
The excitation power of the regulator can be simulated with one medium
frequency power during the static test, which is different from the actual excitation
power. It can not be utilized for large power open loop test but for adjusting the
synchronous circuit of the regulator and load current output of the power unit.
Therefore during the test, the self excitation constant voltage or synchronous
measurement circuit of the regulator shall be carefully inspected, and the
synchronous pulse sequence of single regulator high-speed input port shall be
observed, to verify its accuracy and reliability.
3. Double generators—variable excitation mode
Under such excitation mode, the excitation power is supplied by the excitation
transformer at the generator side. Part of the power of the excitation equipment is
output to the exciter for excitation, to control the output of the exciter.
As the excitation power is derived from the end of the generator, the
excitation equipment shall be equipped with the initial excitation equipment.
When the equipment undergoes initial excitation, the regulator may operate under
lower voltage for some period of time; when it endures the static test, it shall be
confirmed whether the synchronous circuit can provide accurate synchronous
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pulse when the regulator works under extremely low voltage of the excitation
power.
As the frequency of the excitation power is not medium frequency any longer,
some inconvenience may be brought to the static adjustment. Under such
excitation mode, the output current of the excitation equipment is not great, but
the setting of the PID parameters of the regulator may be more complex that self
shun excitation.
4. Self shunt excitation mode
The self shunt excitation is the current popular excitation mode, which is
characterized by no rotating motor, simple structure and better control
characteristics.
The foregoing can be comprehensively consulted about the static adjustment
of the control part of the regulator. Key points for adjustment of the power part:
a As the power part sustains high voltage and large current, high
requirements are imposed on its insulation. Considering restriction in terms of
conditions, the voltage withstand test may not be completed in the ex-factory test;
when the site static test is carried out, the comprehensive AC voltage withstand
test shall be first considered. The key items are three input side and DC output
side to ground of each unit. In such voltage withstand test, the gate electrode,
cathode, anode or grid electrode of IGBT, source electrode and drain electrode
shall be short connected, to protect safety of elements; the resistance capacity
absorption network and meters in connection with the test circuit shall withdraw
from their operation. The withstand voltage of the test is related to the rated
excitation voltage of the generator (the rated excitation voltage is 5~10 times
rated excitation voltage, and not lower than 1,500V).Such test is destructive, so
more tests are not preferable.
b The meters of the power cabinet shall give correct indication, and the
insulation of the meters and wiring shall be inspected.
c If the power cabinet undergoes the forced cooling through the fan, the
direction of the cooling air and air pressure relay shall be inspected before the
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equipment closed loop operates.
d The wiring and insulation of the de-excitation circuit shall be carefully
inspected, and the dusts and foreign substances near the de-excitation switch
and de-excitation resistor shall be cleared off. The de-excitation switch of the zinc
oxide non-linear de-excitation shall not be opened under low voltage and small
current, to avoid contact burning due to failure to establish voltage. For
double-break de-excitation switch, the on-off consistence between double breaks;
for three-break de-excitation switch, in addition to the on-off consistence between
double breaks, the off-on time matching situation of the third normally closed
break. It shall be ensured that normal closing is performed by closing, normal
opening and disconnection; and normal closing is carried out by disconnection,
normal opening and closing.
e The initial excitation circuit provides the initial excitation current. During the
static test, the initial excitation command shall be simulated, to make the initial
excitation contactor act, and whether the excitation voltage amplitude is suitable
or not, and whether the initial excitation time is normal or not shall be checked.
The initial excitation time is generally set to be 3~6 seconds.
For the excitation equipment put into operation in the new plant, the test items
shall be more than reformation items in old plant, and more comprehensive
requirements are imposed on the excitation equipment. The detailed test scheme
shall be prepared in advance.
Regardless of the excitation mode, closed attention shall be given to the
following key points:
a Most parameters of the micro-computer adjuster can be on-line set.
However, all measured values of the electric quantity shall be verified before
being subjected to the static test.
b Under some rare circumstances, the setting value of the regulator may be
changed by mistake. Except artificial factors, when the equipment operates in the
environment with serious electro-magnetic interference and many and high power
harmonic components, the regulator shall undergo power connection and
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disconnection tests before being subjected to static test. At the same time, close
attention shall be given to the interference of the relay and contactor in the DC
operation circuit towards the display link of power supply and adjuster.
c The switch power supply of the regulator is designed to be 50Hz; when the
medium frequency is utilized as the input power supply, special treatment is
required.
d The panel of the adjuster is provided with one “pulse cutting” button (with
anti-error operating cover), which is utilized to send/cut off output pulse of the
adjuster. In the test it can be utilized to connect and disconnect the regulator,
while the working power of the regulator is unnecessary to be cut off. During the
static test, check whether the “pulse cutting” switch is correct or not. The
oscillograph is utilized for measurement.
5.2.3. Dynamic test of adjuster
After the static test is completed, full preparations shall be made for the dynamic
test to be done, which include treatment scheme and measures under various
abnormal circumstances.
1. Preparation prior to test
The preparations for the test, in addition to necessary tools and equipment,
shall at least include:
a No remaining problem upon completion of the static test;
b Prepared comprehensive dynamic test scheme.
c Full accident forecast and emergency measures for each test item.
d Related personnel for test and their understanding of test summary.
2. Fundamental principle of test
The dynamic test shall comply with some fundamental principles:
a Each item of the operation test of the equipment shall be provided with
technical preparations, and not go beyond or violate the design principles. If the
special test items are performed, the comprehensive consideration shall be made.
Such test items shall be reported to the technical leaders of the company and
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executed with the approval of the company and power plant.
b After the equipment closed loop operates, the other necessary personnel
shall be involved in switch operation and electric quantity measurement, who
shall fulfill their monitoring responsibilities.
c The measurement of high voltage grade electrical quantity shall be in strict
accordance with the use procedures of the instruments and meters, and the
protective measures like insulation shall be taken.
When the oscillograph probe
is utilized, only one earth line can be applied.
3. Test steps
The dynamic test has higher requirements upon test time, and such test shall
be arranged in order.
Inspection before test
a Check whether the fasteners of all key positions (e.g. socket, transformer
wiring, cable, bus bar, etc.) are loosed or not;
b Re-check the fuse and switch of the synchronous circuit and power circuit
from excitation power to exciter.
c Check whether CT circuits are subjected to open circuit or not.
d Check pre-set parameters of the regulator.
In the case of self shunt excitation system, one initial excitation step-up
operation shall be simulated prior to commencement of the test: stop operation of
the regulator, push initial excitation button, and measure amplitude of three-phase
voltage of excitation sub-side and synchronous circuit. At the same time, record
the measured value of excitation PT, and estimate the voltage amplitude at the
excitation sub-side (namely, voltage of excitation power) is normal or not.
Regardless of excitation mode, in the first step-up the generator terminal voltage
shall not be boosted to the no-load rated value one time; the generator shall
maintain operation under low operating condition, and at the same time, check
whether the circuits are in normal operation. Attention: at this point, the power
supply circuit of the fan of the power cabinet shall be switched to the power
supply for the power plant.
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Basic test items:
30%~120% voltage adjustment (no load): after being subjected to various
tests, the generator shall operate normally, and main circuits shall be in normal
operation. The power plant shall confirm the basic step-up conditions of the
system.
Set the given setting value of the micro-computer excitation regulator at 15%,
close DC output switch (for the self excitation system, the given setting value is
set at 10%~30%, initial excitation), observe whether the generator voltage is
normal or not, increase given value, and pay attention to relevant changed in the
generator terminal voltage. Increase or decrease the given value to adjust the
generator terminal voltage, observe the full-process voltage stability and
temperature of power circuit. PID parameters shall be properly adjusted based on
the demands. Voltage adjustment range is 10%~120%, of which the upper limit is
restricted by the excitation transformer and generator withstand voltage.
10% or 5% step (no load): the step test can show the control characteristics of
the excitation equipment, and then one group of suitable PID parameters are
selected for the subsequent tests. Such test shall be first completed by one
regulator, and then another regulator is utilized to verify the set parameters in the
test.
In the first step, the generator terminal voltage shall not exceed 90% of the
rated value. After the test effect is determined, the rated value commences its
step. The overshoot, adjustment time and adjustment times of the step shall be
observed and recorded, and based on this, whether the PID parameter are
optimum or not is judged.
Note: The setting of PID parameters requires understanding of fundamental auto
control principles, as well as certain practical experiences. Generally speaking, if the
generator terminal voltage suffers overshoot during test, the differential and magnification
factor can be increased; if the voltage involves too many swinging times, the differential
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time can be decreased, or the integral time can be increased.
100% zero-initial voltage boosting (no load): the set parameters in the step
test are utilized for such test; if the test effect is not ideal, the PID parameters can
be properly adjusted. At last, the results of these two tests are generalized, and
one group of PID working parameters are chosen.
Note: some power plants may be not accustomed to boosting voltage to the rated
value in start-up one time, so the specific practice depends on the user. Under such
circumstance, the index of zero-initial voltage boosting is not as important as that in step
test.
For the self shunt excitation system, the process of initial excitation voltage
establishment shall be involved before all tests. In fact, one zero-initial voltage
boosting of the generator has been completed. Before knowing the optimum PID
parameters, we can set the start-up setting value to be 20%~30% of the rated
value, and the default PID parameters are applied to boost the voltage to the
setting value.
After the voltage is successfully established, the trigger signal of power
elements, the waveform between source electrode and drain electrode (cathode
and anode) of each power element and rotor voltage waveform shall be
immediately measured; when the generator terminal voltage approaches the
rated value, re-measurement is required. During the subsequent tests, the
waveform of each power element shall be continuously monitored.
It is impossible that working characteristics of large power elements are
completely identical, so their waveforms are also different. The analysis shall be
based on the actual situation, to accurately judge it is normal or abnormal.
Manual-auto switching (no load): HWJT-08 series regulator has one auto
channel and one manual channel, and the adjustment objects of them are
different; the former aims at the constant generator terminal voltage, while the
latter at the constant excitation current. Prior to switching test, it shall be
confirmed that the current working channel is in normal condition. In the case of
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abnormality, the current regulator shall be rapidly cut off.
The manual channel is the primary operation mode, so its parameters are all
set to be relatively conservative.
In the analog regulator, when the excitation PT is disconnected, it may be
switched to manual operation. The microcomputer regulator utilizes measured
values of two PTs for operation, and disconnection of one PT may exert no
influence upon its operation. The regulator is not provided with the auto switching
function of “auto” and “manual” channels. When two PTs are subjected to fault,
and the regulator fails to measure the generator terminal voltage in the
short-circuit current-boosting test of the generator, the manual channel shall be
put into operation.
After the generator is connected to network, the manual/auto switching test
can be repeated, to observe whether the reactive load of the generator is stable in
switching or not.
Note: the manual and auto channels of the regulator trace the output of the other,
and such tracing process takes some time. Therefore, the adjustment of the tracing
channel shall be waited in switching.
Frequency characteristics test (no load): such test can be conducted together
with the lower frequency protection test. First, the setting value of the low
frequency protection is reduced to the lower value of the frequency
characteristics test. The generator frequency is changed within the test range,
and the corresponding generator terminal voltage is recorded at this point. When
the frequency characteristics test is finished, the voltage frequency is maintained
at 50HZ; the setting value of the lower frequency protection is changed to the
pre-set value, and the generator frequency is reduced to make lower frequency
protection act. The generator frequency, when the lower frequency protection acts,
is recorded and compared with the pre-set value.
The action of the lower frequency protection may de-excite the regulator, and
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the generator voltage is rapidly reduced to zero. For IGBT excitation system, the
positive group output is decreased to zero; if the excitation equipment is provided
with reverse group circuit, the reverse group output is set to be maximum. For the
thyristor excitation system, the thyrsistor trigger pulse is adjusted to the inversion
angle (generally 1300).With respect to the hydropower generating unit with
frequent start-up and shut-down, it tends to operate under low frequency. The low
frequency operation may damage the inductive load of the transformer, which is
designed for this purpose.
If the zinc oxide non-linear de-excitation cabinet or unit is involved, the
de-excitation switch sub-section test shall be separately conducted. Close
attention shall be given to de-excitation time and switch contact.
The thermal power generating unit is rarely subjected to low frequency, and
even the low frequency protection test may be not required. However, the low
frequency protection shall be still put into operation. Generally speaking, if the
frequency of the generator terminal voltage is more accurately measured, then
the low protection will suffer no fault without any test.
Over excitation restriction test (no load/network connection): before the
generator is connected to the network, the no-load excitation current is utilized to
calibrate the measured value of the excitation current of the regulator, then the
duty ratio of the excitation restriction IGBT (or thyristor trigger angle) is set, to
make the over excitation restriction act by setting over excitation restriction value.
Observe the action time and whether the excitation current is restricted after the
over excitation restriction, and finally re-set the duty ratio of the over excitation
restriction IGBT (or thyristor trigger angle) and over excitation setting value, to
make full preparations for the over excitation restriction test after the network
connection.
After the generator is connected to the network, the generator carries
adequate reactive load, to make the excitation current to reach the over excitation
restriction setting value and then to make the over excitation restriction act. The
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effect after action is checked. When the generator is connected to network, the
set duty ratio of the over excitation restriction IGBT (or thyristor trigger angle)
shall be more than (the thyristor trigger angle shall be less than) no-load rated
value, to avoid phase advance operation of the generator. The duty ratio of the
restriction action (or trigger angle) shall be preferably set to be the setting duty
ratio of the excitation restriction (or trigger angle), to ensure no occurrence of
reactive fluctuation when the over excitation acts.
Low frequency restriction test (network connection): prior to the test, the
stator current measurement coefficient of the generator shall be carefully set, to
make the active and reactive measured value to be basically consistent with the
standard value. The desired phase advance limits are confirmed, which are
generally represented by two points: phase advance depth of rated active power
and maximum phase advance depth of zero active power. Both of them are
respectively set, and the phase advance operation is respectively made
corresponding to these two points, to verify the low excitation restriction function
of the regulator. If the excitation equipment is composed of two regulators, the
operation mode of single regulators is respectively adopted to complete the test.
If the test time permits, the parallel operation mode of two regulators can be
adopted for such test.
As over depth of the generator phase advance may result in instability of the
generating unit, one regulator can withdraw from its operation for standby during
such test, and its given voltage is set to be slightly higher than the no-load rated
value. Once any accident occurs, the regulator can be put into operation, and
another one is cut off.
For the excitation equipment composed of two regulators operating in parallel,
the switching test of two regulators may be conducted after the generator is
connected to network. In fact the test is very simple: if two regulators are in
normal condition, then they just need to be switched when their control duty ratio
(or trigger angle) approaches each other. The foregoing only covers the manual
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switching mode. As a matter of fact, the regulator also has the auto switching
function for fault. However, under normal condition, such function is difficult to be
simulated.
Load rejection test (network connection): for the hydraulic power plant, the
load rejection is an important test. Such test is generally conducted three times,
i.e. 50%, 75% and 100% of rated load. During the test, as the generator rejects all
loads abruptly, the disappearance of the stator current and increase of rotating
speed will rapidly boost the generator terminal voltage; at this point, the excitation
regulator shall quickly adjust the voltage to the normal value (as the difference
adjustment is different, the stabilized voltage may be slightly higher or lower than
the value before load rejection). At this point, the overshoot of the generator
terminal voltage shall not be more than 15%, adjustment times not less than 3
and adjustment time less than 5s (for the hydraulic power AC excitation system,
owing to such factors as time constant of generating set and over speed of water
turbine, the index may be slightly inferior).
When the load rejection or 10% step test is conducted, the pointer type
analog instrument is generally utilized to observe the generator terminal voltage.
Close attention shall be given to the mechanical damping and mechanical inertia
of the analog instrument, to avoid wrong test conclusions.
The operation test of the excitation equipment under different excitation modes is
slightly different. If the generator is of separate excitation mode, the regulator may
provide minimum output; otherwise, the regulator can only start to enhance the
excitation current from certain start point (10%～30%Ue). The start point is the given
voltage when the regulator makes initial excitation. The start point may not be over
low: its minimum amplitude shall make the regulator synchronous and power
elements operate normally.
After the dynamic test is concluded, the generating unit is put into trial operation.
During the trial operation, close attention shall be paid to the temperature increase of
the power part of the regulator and transformers. If the excitation equipment is the self
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shunt excitation system, the current sharing at AC and DC sides of the power
cabinets shall be carefully inspected. The current sharing at DC side is expressed
with the current sharing coefficient, which shall be more than 0.85. The current
sharing at the AC side means the balance of three-phase current at the AC input side
of the power cabinet. The AC current sharing of each rectifier cabinet reflects the
magnitude of the on-state voltage drop of its rectification elements and consistence of
its laid cables. The magnitude of the current of each phase of the excitation
transformer can be known by integrating the AC current sharing of each rectifier
cabinet. If the current of each phase is subject to wide difference, the excitation
transformer may suffer abnormal noise and vibration.
5.2.4. Test records
Prior to the test, one perfect test scheme shall be prepared, to schedule the test
and arrange relevant test time and personnel. The scheme shall cover the test items
and their required time, execution sequence and points for attention. If necessary,
some emergency measures shall be reasonably included.
After the operation test is finished, the test results shall be immediately
summarized. In case the equipment is subject to some alteration during the test, the
details and cause of such alteration shall be in time recorded, and written into the
document for record by the power plant and the company.
Finally, one test report shall be formulated, which shall cover the introduction to
the production functions, static test equipment, method, steps and data and operation
instructions of the equipment.
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Part VI Basic Operation Methods and Maintenance of
Equipment
6.1 Basic operation
As the operation of the excitation system varies with the power plant, some basic
items in respect of the operation are only introduced herein, and the specific
operation shall be carried out in reference to the drawing and related procedures.
6.1.1. Safety requirements and basic regulations
Safety regulation
Safety rules
When the operator works within the excitation system, the warning shall be given.
Otherwise, the contact with the live parts may result in severe personnel injuries. For
this reason, the design shall take into consideration all live parts of over 50V within the
equipment for protection. Without receiving some training and taking necessary
precautions, the maintenance personnel shall not enter the cabinet for operation.
图标 Icon
意义 Meaning
危险 Danger
当心带电 Be careful! It carries electricity!
The instructions hereunder are applicable to special circumstances of high
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voltage excitation system.
The parts within the excitation cabinet directly contacting with the excitation transformer
sub-side and generator rotor magnetic filed winding (radiator and copper busbar) carry
extremely high voltage, and the contact with them may bring about the danger of electric
shock. Therefore, the safety shield shall be erected to avoid accidental electric shock. To
measure the electrical elements of the equipment in service, such safety protection
equipment shall keep some distance from the live object. It shall be specially noted that
the maintenance personnel shall receive the relevant training. It is of crucial significance.
As the excitation transformer sub-side and generator rotor magnetic filed winding
are subject to high voltage, the extremely large short-circuit current may be caused
within the excitation cabinet.
It shall be specially pointed out that the discharging resistor of the de-excitation
switch and magnetic field circuit is directly connected to the generator rotor winding,
there is enormous danger of the electric shock. For this reason, the cabinet shall be
supplied with the protection equipment to protection personnel safety.
If such protection equipment is removed, the maintenance personnel shall be
kept distant from the danger of high voltage and large current. The cabinet door shall
be provided with the warning sign, to warn the maintenance personnel of voltage
(over 50V) within the control cabinet. What is most important, it is used to warn the
people that the voltage within the rectifier cabinet may be more than 1,000V, and the
current may be extremely large. During the operation, when the door of the control
cabinet is opened, such warning is a kind of protection.
The maintenance work can be conducted only when the voltage is cut off, and the
protective measures are taken. Otherwise the following precautions shall be observed:
the maintenance personnel shall not get close to the work area at will, and the safety
area shall be marked “high voltage! Danger!” with yellow signs.
Owing to control mistake or the reason of other persons, the off switch may be
closed again. To avoid such case, the relevant protective measures shall be taken
(e.g. the switch with the key is applied, to avoid re-closure of such switch by mistake).
Consequences arising from negligence
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Any unconformity with the safety regulations may bring about severe damage to
the equipment.
Warning: if the system carries electricity, and the cabinet is not supplied with the
protective equipment, the danger of electric shock may be caused to the operators
and any other person close to the live equipment.
If the required maintenance is not completed in whole or in part, the enormous
economic loss may be resulted in. In particular, if the rectifier cabinet is subject to any
remaining dirt or dust, the danger of high voltage flashover may be brought about.
Requirements upon operators
The operators shall be well acquainted with the safety regulations, influence of
the excitation system upon the system variables (such as generator voltage and
reactive power), their working sites and buttons, operation indication and warning
signals of the excitation system before the equipment cabinet, and the consequences
of the local commands and meaning of the remote warning signals.
The operators shall be familiar with safety regulations and installation operation,
and receive the training in respect of repair and maintenance; they shall be
acquainted with the control principles and related operations, and the warning in
connection with the excitation system issued by both the excitation equipment (local
control) and the control room (remote control, see the operation guide). The operators
shall have abundant experiences in both the power supply of the excitation equipment
and such accidents as emergency shut-down, and have the capability of shutting
down the system under emergency. In addition, they shall get familiar with the
measures against accidents on the work site, and participate in the training related to
first aid and fire prevention.
Description of emergencies
 Fire:
The workers shall know the location of the fire extinguisher and emergency exit,
and have the capacity of using the fire extinguisher. The fire extinguisher is separated
into halon extinguisher, CO2 and foam.
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CO2 extinguisher is especially designed for fire extinguishing of the electrical
equipment, which has no direct harm to the personnel.
The foam extinguisher is exclusively used for fire extinguishing of non-electrical
equipment. It can not be used for fire fighting of electrical equipment. It has direct
harm to the personnel.
When the system gets fire, the excitation shall be cut off locally or in the control
room; if necessary, the emergency shut-down equipment shall be applied (see
operation guide).Following this, all power sources of the system shall be disconnected.
When the live cabinet gets fire, the CO2 fire extinguisher is only needed instead of
foam or water extinguisher!
 Electric shock
1. First cut off the excitation power supply locally, and then disconnect all power
sources of the equipment.
2. Rescue injurers from the danger, and let them lay on the ground. By reference to
the procedures in respect of the electric injury cure, carry out the bridle-wise cure
practice, and call for help.
Basic regulations
1.1 The personnel other than the manufacturer’s persons are not allowed to plug
or pull the connectors carrying electricity!
1.2 Before the excitation system is put into operation, the control power switch
shall be first operated, followed by the generator signal (analog quantity and switch
quantity) and AC (DC) power input switch. In the case of no any abnormality, the
regulator is well adjusted (the setting depends on different test and operation
requirements) and stabilized, before the power output switch is applied. The
de-excitation switch, if any, can be first applied.
1.3 The exiting sequence of the excitation system is contrary to “2”, namely, first
disconnect power output switch, then power input switch, followed by generator signal
input switch and power supply switch.
Note: during the test, when the equipment withdraws from its operation, only the
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power output switch needs to be switched; but for the parallel system involving two control
units, the output control pulse of the regulator shall be disconnected.
The generator input signal and regulator control power can share the same switch.
1.4 For double or more power units that are connected in parallel, when one unit
withdraws from its operation, the other working units shall be in normal output and
free from fast fusing, fan shut-down and power switch loosening, and the protective
measures for the personnel shall be taken.
1.5 For parallel operation of double or more power units, when one non-working
unit is put into operation, its links shall be normal and free from short circuit, fast
fusing, fan shut-down and power switch loosening. The protective measures for the
personnel shall be taken.
6.1.2. Input and withdrawal of excitation equipment
1. The switches and buttons of the excitation equipment shall be in the following
state:
 The de-excitation switch FMK has been closed;
 The switches at both AC and DC sides of the power cabinet have been
closed;
 AC and DC power fuse has been applied;
 Initial excitation circuit is in normal condition, and the initial excitation power
has been applied;
 The power switch of the regulator has been applied;
 The backboard switch of the control box has been closed, the panel gives
normal indication, and the buttons are all not pushed;
 Given value of start-up setting voltage is correct;
 After the rotating speed is raised to the rated value, push the start-up button
to initialize excitation and boost voltage;
 Through magnetism enhancing and reducing operations, boost the voltage
to the rated value, and get ready for network connection.
2. Withdrawing operation of excitation equipment
 After the generator is put into operation, push the “de-excitation” button;
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after the generator terminal voltage is reduced to minimum, disconnect the
de-excitation switch
 If necessary, disconnect the switch at AC side of the power cabinet
 If the power is totally disconnected with the excitation equipment, only the
power fuse before the cabinet needs to be disconnected.
6.1.3. Operation of control unit
1. Start-up
If the regulator is in the off-state when the generating unit has just completed
big repair or small repair, the following steps can be consulted about the start-up
operation:
1) Recover the wiring affected during the repair of the excitation equipment,
confirm that the power fuses are at the off positions, and then supply DC
operation power to the regulator.
2) Close de-excitation switch.
3) Measure the voltage along the power fuses, and close the fuses after no
error is confirmed.
4) Through the power indicator lamp on the regulator panel, confirm that the
regulator power is in normal condition.
5) Apply the AC switch of the power part and then DC switch, and confirm that
the indications of switch positions are right.
After the above steps are finished, the generating unit can be started, and the
voltage boosted.
If the generating unit is always in the standby state, the operator shall, before
starting the generating unit, check the aforesaid Items 2 and 4; at the same time,
confirm that the initial excitation circuit is in normal condition.
If the generating unit is in operation, the operator shall check Item 4 on a
periodical basis. In addition, close attention shall be paid to the temperature
increase of the power circuit, and check whether the indication of the output
current of the power branch is close to the normal position.
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The voltage establishment of the generator shall meet the following
conditions:
1) Close de-excitation switch.
2) Open generator outlet breaker (the generator is in the no-load state).
3) Close the switches at both AC and DC sides of the power cabinet.
4) Fast voltage boosting: when the regulator receives the start-up command,
or the start-up button is pushed, the process of fast voltage boosting is
commenced. The generator terminal voltage may be boosted to the former given
voltage pre-set by the regulator.
2. Shut-down operation
1) Reduce active load to zero.
2) Reduce reactive load to zero.
3) When the generator is connected to the system, the “de-excitation” signal
is sent from the central control room or locally, the generator terminal voltage is
automatically reduced to zero.
To sum up, if the generating unit is started or shut down in a remote manner, the
process of both voltage boosting and de-excitation can be automatically finished. The
operator only needs to conduct the “magnetism enhancing/reducing” operation to
control the generator terminal voltage or reactive power. Other operations are
generally not required. The repair & maintenance personnel can consult the above
descriptions for correctly operating the equipment during start-up and shut-down
thereof.
6.2 Abnormality handling
6.2.1. General abnormalities
During the operation, if any abnormality occurs, the “abnormality” indicator lamp
of the equipment will be on; the type of abnormality signal can be displayed by the
abnormality indicator lamp (red) on the panel of the control box. Example:
When the “break” lamp is on, it indicates that the excitation PT or instrument PT is
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subjected to break fault, while the regulator can operate as usual. Once PT is
recovered from the fault, the break signal will be automatically reset.
When the “over excitation” lamp is on, it indicates that the “over excitation
restriction” acts, and the regulator will restrict its output. The excitation current is
restricted to the setting value, and after about 20s time delay (which is related to the
current after restriction; the over excitation will be reset only when the generator rotor
undergoes favorable heat dispersion), the over excitation restriction is reset, and the
regulator operates as usual.
When the “low excitation” lamp is on, it indicates that the “low excitation
restriction” acts, and the regulator will restrict further reduction of its output. The
excitation current is automatically increased, the low excitation state is released, low
excitation lamp is off, and the regulator operates as usual.
When the “low frequency” lamp is on, it indicates that the measured PT voltage
frequency of the regulator is lower than the setting value. When the “low frequency
protection” acts, the regulator resets the given voltage, namely, the output becomes
zero.
When the “de-excitation” lamp is on, it indicates that the regulator resets the given
voltage and current, to reduce the generator terminal voltage and excitation current to
zero.
The results of “low frequency” and “de-excitation” are the same. In each case, the
output of the excitation equipment is made zero. In addition, both are locked and
become invalid after the generator is connected to the network.
The foregoing relates to the protection functions inside the excitation regulator.
These protection action signals serve as the abnormality signals during the operation
of the excitation equipment, which do not mean that the regulator suffers any fault or
damage.
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6.2.2. Fault and abnormality of excitation equipment
The essential meaning of the excitation accident is over excitation protection. The
“over excitation protection” action of the excitation regulator may make the regulator
withdraw from its operation automatically, and at the same time, the “over voltage
protection” signal is on and can not be reset. The “over excitation protection” is not
identical with the aforesaid “over excitation restriction”. The latter can be automatically
reset after the regulator restricts its output, and the regulator can continue operating.
If the “over excitation protection” of the regulator acts, the excitation equipment
will cease its operation. The “over excitation protection” signal lamp will not be reset
after the equipment is disconnected with the power supply.
Handling method: such case has been expressly defined as excitation fault. If
such case occurs, the equipment shall be stopped, and check whether the related
units are in normal condition.
In addition, other faults may also occur during the operation:
1) Output current of the power cabinet is abnormal (when there is redundant
power unit)
Phenomenon: the current of two cabinets is not consistent and suffers wide
difference.
Under normal conditions, the current sharing coefficient of the power cabinet is
generally not inferior to 85%.
The current unbalance of the power cabinet may be caused by the damage to the
elements of the power cabinet. For example, the damage to or fast fusing of one
rectifier tube results in the open circuit in the branch, and the decrease in the DC
voltage supplied to the AC circuit may reduce its output; however, as the regulator
may maintain the generator terminal voltage constant, the output current of another
cabinet may be increased accordingly.
Handling method: once such case occurs, the operator shall reduce the output
of the excitation current, to decrease the current load of the power cabinet; if
practicable, he shall stop the equipment and check it.
2) Operation of single power cabinet
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When the case 1) or 4) or 5) hereunder occurs, the single power cabinet of the
excitation equipment may operate; when the single power cabinet runs, the cooling
fan within the power cabinet shall, if necessary, be used to reduce the temperature
increase of the power elements.
3) The excitation transformer is subjected to temperature increase or over great
noise.
Phenomenon: the temperature measuring instrument of the excitation
transformer indicates that the temperature of one phase exceeds 115℃.
The excitation transformer is generally equipped with the cooling fan, which is
started when the body temperature of the excitation transformer reaches 90℃.In
addition, the fan may issue warning when such temperature exceeds 130℃.Under
general circumstances, over temperature increase may not occur.
Handling method: if the temperature rises to 115℃, this may be resulted in by
non-started fan or the problem of the transformer. Once the temperature continues
increasing to 130℃, the equipment shall be stopped and inspected.
If the transformer in service suffers abnormal noise and vibration, this may be
caused by unbalance of three-phase current. Check whether the output current of the
power cabinet is balanced or not, and the handling method is the same as Item 1) of
abnormal output current of power cabinet above.
4) The power cabinet is subjected to fast fusing.
Phenomenon: the fusing indicator lamp on the door of the power cabinet is on,
and at the same time the central control room sends out the sign of “excitation
accident”.
Such fault may result in inconsistence in output current of the power cabinet.
Handling method: if the fuse of the single cabinet is fused, the power cabinet
shall cease its operation, while the generator can operate normally, and the regulator
automatically restricts the force excitation multiple. If several power cabinets suffer
such fault, they shall be stopped and inspected.
5) The switch at the DC side of the power cabinet is tripped.
Phenomenon: when the power cabinet operates normally, the switch at the DC
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side is abruptly tripped, and the indicator lamp on the cabinet door indicates the “off”
state.
When the power cabinet is subjected over current, the switch at the cabinet outlet
is tripped; otherwise the switch may be tripped by mistake or mis-operated.
Handling method: same as “Item 1)” in respect of current abnormality.
6) Fault of regulator power
Phenomenon: the external input of the regulator is normal, while the indication of
the power inserters disappears.
Such phenomenon indicates that the internal power supply of the regulator is
subjected to the fault. The operation of the excitation equipment is executed by
another regulator.
Handling method: push the “pulse cutting” switch of the faulty regulator, to
cease its operation. Such fault is handled when the regulator is stopped later.
7) Reactive swinging of generator
Phenomenon: the reactive power of the generator continuously suffers
oscillation.
Handling method: through the LCD of the excitation monitoring unit, observe the
duty ratio of the regulator or the trigger angle output of the thyristor is subjected to
great fluctuation. One faulty or abnormal (in the case of no fault or abnormality, the
regulator with greater HG fluctuation is selected) regulator is selected, and its “pulse
cutting” switch is pushed to cease its operation. If the fault is not removed, the “pulse
cutting” switch of the regulator is released and put into operation again. Then another
regulator is cut off (the active swinging of the generator may also result in its reactive
change. The regulator may control such reactive change, to prevent it from becoming
swinging. However, the rotor voltage may be subjected to greater change than usual,
which is obviously a normal phenomenon. The unusual reactive swinging may be
caused by the system fluctuation or the load change of the adjacent generating set;
the measurement of the regulator or abnormality of the power circuit may also result in
the fluctuation in the generator terminal voltage or reactive load, but such possibility is
faint).
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8) The generator fails to establish voltage
Phenomenon: in the case of normal start-up, the rotating speed of the
generating set has reached the rated value, while the generator is without reactive
terminal voltage.
Handling method: first check whether there is the “initial excitation failure” signal
or not. If there is such signal, it proves that the conditions of the initial excitation
operation have been met, and the priority of inspection shall be given to the following
items:
1. Whether the initial excitation power is put into operation or not?
2. Whether the “de-excitation” button is at the “off” position or not?
3. Whether the AC and DC switches of the power cabinet are closed or not?
4. Whether the given voltage of the regulator is successfully set or not?
If there is no “initial excitation failure” signal, it can be judged that the conditions
of the initial excitation are not met, and the priority of inspection shall be given to the
following items:
1. Whether the de-excitation switch is closed or not?
2. Whether the “auto initial excitation set plate” is applied or not?
3. Whether the auto start-up command is given or not?
After the cause for failure to establish voltage is removed, the initial excitation and
voltage boosting can be performed manually, while the generating set maintains its
rated rotating speed.
The integration of various abnormal cases shows that after the power part of the
excitation equipment suffers abnormality, the load shall be in time reduced to ensure
continued safe operation of the generator and excitation equipment, and the
equipment shall be preferably stopped for handling. After the control part suffers
abnormality, the regulator may try to make use of the protection functions to achieve
continuous operation of the generator; if the abnormality continues developing, it can
be regarded as the excitation fault, and the equipment shall be stopped for repair.
If you have any question in respect of the excitation equipment, please contact
with the manufacturer for technical support on telephone or technical services on site.
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6.3 Points for attention for operation
Basic safety items:
Before the equipment is put into operation, the control power switch shall be
operated first. After it is confirmed that the regulator is in normal condition, the
de-excitation switch is applied, followed by the AC switch of the power circuit.
Before the excitation control equipment withdraws from its operation, the power
output switch shall be first disconnected, followed by the power input switch and then
excitation power switch.
6.3.1. Points for attention for operators
1) They are not allowed to modify the working parameters of the microcomputer
excitation regulator;
2) They are not allowed to conduct step operation after the generator establishes
voltage with no load;
3) When the equipment operates normally, they are not allowed to conduct
“manual” or “auto” switching operation ("manual” button of the regulator and “manual”
switch of control cabinet);
4) They are not allowed to remove the output pulse of the regulator at liberty
(“pulse cutting” switch of the regulator);
5) They are not allowed to cut off the power supply of the control box when the
regulator is in normal operation;
6) Except special circumstances, when the regulator is in normal operation (with
output), they are not allowed to cut off the switches of the excitation equipment at
liberty.
6.3.2. Points for attention for repair and maintenance personnel
1) They are not allowed to modify the working parameters of the microcomputer
excitation regulator;
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2) They are not allowed to conduct step operation after the generator establishes
voltage with no load;
3) They are not allowed to conduct “manual” or “auto” switching operation
("manual” button of the regulator and “manual” switch of the excitation equipment);
4) They are not allowed to apply or remove the output pulse of the regulator at
liberty (“pulse cutting” switch of the regulator);
5) They are not allowed to cut off the power supply switch of the control box when
the regulator is in normal operation;
6) Except special circumstances, when the regulator is in normal operation (with
output), they are not allowed to cut off the switches of the excitation equipment at
liberty.
6.4 Basic maintenance
The equipment has high reliability, thus generally requiring no special
maintenance. When the equipment is stopped, attention shall be only given to the
following points:
1. Check whether the inserters are loosened or not.
2. The de-excitation switch shall be periodically inspected, and the anti-rust oil on
the working polar plane of the magnet shall be cleared off. The rotational axes and
friction parts shall be filled with lubricant on a periodical basis, to ensure use safety
and reliability.
3. The knife switches shall also be cleaned, to avoid inflexible operation due to
accumulated dirt; if the drive mechanism is found to be inflexible, it shall be
immediately maintained or replaced, to ensure absolute safety.
The user shall
periodically check whether the fasteners are loosened or not, and the grounding part
is in good condition or not.
4. The dusts and foreign substances on the equipment shall be cleared away,
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especially on the power elements, cables and bus bars, to eliminate hidden danger of
accidents such as short circuit, reduced insulation and unfavorable heat dissipation
caused thereby.
5. The regulator is connected to the power supply, to check whether the switches
and indicator lamps are in good condition or not.
If more careful inspection is required, refer to the related items within the manual.
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Part VII Equipment Structure
HWJT-09C excitation adjustment system is generally composed of the excitation
control part and excitation power part. Except the small power excitation output
adjustment system which can be made up of single cabinets, under general
circumstances, the excitation control part separately forms one cabinet. The following
is the schematic diagram of composition of one typical excitation system.
带门正视 Front view with door
去门正视 Front view without door
侧视 Side view
背视 Back view
In the excitation regulator cabinet, the whole system is generally composed of
several parts, which is introduced one by one as follows:
1, 2, 3. Indicator lamp, meter and switch, button
The indicator lamp is generally used to indicate the state of working power of the
system and working state of the regulator; the meter setting is normally utilized to
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indicate the voltage, current or power closely correlated with the adjustment system;
the switch setting is usually applied to apply or remove the working power of the
regulator and special working modes of the regulator like de-excitation; the button
setting is primarily used to enhance or reduce magnetism for the generator,
equivalent to remote operations.
4. Industrial HMI
Industrial HMI is mainly used for HMI display, and the displays of various sizes
can be selected.
3. Control part of double-channel regulator
This part is the core part of the excitation adjustment and control, which is
generally composed of double-channel DSP excitation control system (symmetrically
arranged on the right and left), including controller case, power amplifier power panel,
control power panel (AC and DC), interface board, host computer board and collection
board. See other related parts of the manual for detailed introduction to the control
part.
4. Touch screen
Under normal circumstances, the regulator is generally operated on the touch
screen; if the regulator is equipped with the matching touch screen, the keys may be
provided for standby.
5. Pulse power amplifier module
The pulse signal sent out by AVR is amplified by the pulse power amplifier
module.
6, 12, 13. Power supply modules
7. Excitation regulator unit
8, 11. Relay module
9. Sampling board function module
10. Communication module
15. Power supply integration board function module
16. Power transformer unit
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Part VIII Order Guide
8.1 Environmental requirements
1. Installation location: indoor;
2. Ambient temperature is -10℃～+45℃;
3. Storage temperature is -25℃～＋75℃;
4. Height above sea level: ≤2000m; relative humidity: ≤90%, without
condensation;
5. Installation vertical inclination: ≤5°;
6. When the allowable vibration is 10~150Hz, the vibration acceleration shall not
be more than 5m/s2;
7. Seismic fortification intensity: ≤ magnitude Ⅷ;
8. The surrounding medium of the service environment shall be free from any
explosion risk and corrosive gas, and the concentration of the conductive dust
contained shall not reduce the insulation level to the allowable limit value.
9. When the altitude exceeds 1,000m, the relevant regulations on maximum air
temperature are as follows:
Height
above
sea level (m)
Maximum
air
temperature (℃)
H≤1000
50
1000<h≤1500
47.5
1500<h≤2000
45
2000<h≤2500
42.5
When the environmental conditions for operation exceed the above regulations,
consultation with our company is required.
8.2 Notices for order
As the design of HWJT-09C excitation regulator can meet the control
requirements of the excitation system under different excitation modes and different
power modes, the user shall, when ordering the equipment, pay attention to the
following items:
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1. Specify the excitation mode of the system. The common excitation modes
include the self shun excitation system, three-generator excitation system and DC
excitation system, and the provision of the schematic diagram of the original excitation
system is preferable. At the same time, the user shall confirm the power control of the
excitation system adopts the thyristor or IGBT.
2. Specify the excitation capacity required by the excitation adjustment. Generally,
the rated excitation voltage and current of the control object, no-load excitation
voltage and current and force excitation multiple required by the excitation system
shall be provided. For the above-mentioned parameters, in addition to the nameplate
parameters, the actual operation parameters shall be provided together.
3. Specify the input & output requirements of the system. Generally, CT
transformation ratio for excitation, capacity of excitation PT and instrument PT, wiring
group type and output voltage and requirements of output photon plate, remote
control and instrument shall be provided.
4. Main wiring mode of the generator system shall be provided.
5. The orientation and voltage grade of the AC/DC excitation control power (for
adjuster) shall be provided.
6. The requirements of installation mode and location and size of the excitation
equipment and cabinet color, as well as operating environment, shall be provided.
Please fill in the following data and requirements, to facilitate our company
in providing you with the products of most reasonable design and optimum
performance.
1. Excitation mode:
(Self
shun
excitation
mode
three-generator excitation mode)
2. Adjuster model:
（HWJT-09C）
3. Related parameters of generator
Items
Generator
AC/DC exciter
Pilot exciter
/
/
Capacity (KVA)
Active power (MW)
Power factor
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Terminal voltage (V)
PT change
/
/
Terminal current (A)
/
/
CT change
/
/
Frequency (HZ)
No-load excitation voltage (V)
/
Rated excitation voltage (V)
/
No-load excitation current (A)
/
Rated excitation current (A)
/
Force excitation multiple
/
/
Main wiring mode of generator
/
/
Different adjustment rate (%)
/
/
DC impedance of excitation winding
Ω/
℃
Ω/
℃
Ω/
℃
Short circuit ratio
/
/
Synchronous reactance Xd
/
/
Transient reactance Xdˊ
/
/
Super-transient reactance Xdˊ
/
/
Rotor time constant of stator open circuit
/
/
/
/
/
/
Tdo
Transient
time
constant
of
stator
three-phase short circuit current Tˊd3
Transient
time
constant
of
stator
three-phase short circuit current T″d3
Notes:
a. Main wiring mode of the generator refers to network connection wiring
mode, namely, expansion unit wiring; the exciter and pilot exciter refer to Y or Δ
mode.
b. For the self shunt excitation system, the force excitation multiple
corresponding to the voltage shall be indicated. For example, the reduction of
voltage to 80% required by the large generating set intends to meet double force
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excitation.
c. Different adjustment rate refers to the maximum value.
4. Type of excitation transformer:
(Oil immersed type, common dry type
or epoxy resin placing dry type), in the case of large epoxy resin placing dry type excitation
transfer, whether the temperature controller and shielded enclosure are required or not shall be
specified.
5. Other special requirements.
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