Series Capacitor Bypass Control and Overvoltage Protection
May 13, 2005
Sponsor: Dr. Brian Johnson (University of Idaho)
Submitted by:
Design COPS
Chris Butterworth - butt1290@uidaho.edu
Michael Dole - dole2239@uidaho.edu
Randy Mallo - mall7208@uidaho.edu
Prasanna Upadhyaya - upad8536@uidaho.edu
Table of Contents
Abstract
1.0 Project Description
1.1 Problem Statement
1.1.1
Primary Objectives
1.1.2
Secondary Objectives
1.1.3
Constraints
1.1.4
Requirements
1.2 Solution Methods
2.0 Status (Function Block Diagram)
2.1 Subsystems
2.1.1
Breaker Bypass Subsystem
2.1.2
Thyristor Circuit Subsystem
2.1.3
Sensing Subsystem
2.1.4
Microcontroller Subsystem
2.1.5
Metal Oxide Varistor (MOV)
3.0 Methods of Solution
3.1 Technical Description
3.2 Theoretical Basis and Fundamental Relationships
4.0 Validation Procedure
4.1 Test Plan
5.0 Results
5.1 Operating Procedures
5.2 Validation Results
5.3 Cost Analysis
6.0 Biography
APPENDIX
a. Specification (Physical and electrical)
b. Bill of Materials
c. Test Information
d. Design Project Status Diagram
e. Schedule
2
Abstract
The power industry uses capacitors inserted in series with a power line to lower
the impedance of transmission lines. A lower impedance line can carry more current
without expensive upgrading of the rest of the line. A problem with this scheme of
operation is that a fault on the transmission system can cause the capacitors to see
overvoltage conditions. To protect the capacitors, metal oxide varistors (MOVs) are used
to shunt energy away. Under sustained overload conditions, the MOVs themselves are in
danger of being damaged. This project implements a method of protecting the capacitors
and MOVs. This will allow the Analog Model Power System (AMPS) to safely include
series capacitance in its modeling settings, thereby expanding the capability of the AMPS
as a teaching and research tool.
3
1.0 Project Description
1.1 Problem Statement
The main objective of this project is to design, construct, test, and implement a
series capacitor overvoltage bypass system for one of the series capacitor banks on the
University of Idaho’s Analog Model Power System (AMPS). Documentation of this
Capacitor Overvoltage Protection System (COPS) will be provided to enable duplication
of the bypass system on the other series capacitor banks, if desired.
1.1.1 Primary Objectives
The primary objective of this project is to design a protection system for the series
capacitors of the AMPS. Initial fault protection will be provided by a MOV placed in
parallel with the capacitor bank. A microcontroller will be used to receive sensed inputs
and control various aspects of the protection system. One option for protecting the MOV
is placing anti-parallel thyristors in parallel with the MOV and triggering them with a
firing circuit. The firing circuit will be setup to gate the thyristors if the energy dissipated
by the MOV is high enough to cause damage. The microcontroller will signal the firing
circuit to gate the thyristors on. A second option being considered is to use solid state
relays to provide a current path around the MOV. For the sake of simplicity, this report
is written designating the thyristor option as the chosen method. A sensing system will
provide data to the microcontroller. In case the MOV and the thyristors fail to reduce the
voltage across the capacitor, the microcontroller will trip a breaker to bypass the MOV
and the capacitor bank in the protected phase. The bypass breaker is a precaution to
protect technicians and equipment.
4
1.1.2 Secondary Objectives
•
Indication lights – In the event the thyristors are triggered or the breaker is closed, an
indication light will show that the system has left normal operation. One indication
light will signal when the thyristors have begun triggering and a second light will
display if the bypass breaker has closed.
•
System expandability – The system will be capable of being upgraded to incorporate
the other phases of the model power system. We will be designing a protection
system for only one capacitor bank. The system will be designed for implementation
of the remaining capacitor banks.
•
Segmented capacitance – The capacitor bank on each of the three phases will be split
to provide three different levels of series capacitance. This is not necessary for the
protection system but has been requested, by the sponsor, for added system
configuration flexibility.
1.1.3 Constraints
The design needs to be small enough to be easily moved with a small cart. The
system will need to be able to successfully handle 20 amps of continuous line current.
The system will also need to be able to operate at a room temperature between 50-85°F
without exceeding junction temperatures of 100°C for the thyristors. Since the protection
system will be implemented and tested on the AMPS, it will have to able to operate at the
existing 208V line to line supply system.
1.1.4 Requirements
For increased reliability, the system will be designed to protect the MOV without
personnel action. The only user interaction required will be to change initial system
variables. Appropriate documentation will be provided for adjusting system variables.
5
1.2 Solution Method
A microcontroller will be used to perform calculations and control the protection
system. The microcontroller will continuously monitor the sensor inputs. Isolated
transducers will be used to provide voltage and current sensing inputs for the
microcontroller. When setpoints are reached indicating that the capacitor bank is
approaching its maximum allowable current, a signal will be sent to gate on two back-toback thyristors; effectively bypassing the MOV and capacitor bank. In the event the
thyristors fail to adequately reduce the voltage, a bypass breaker will close to protect the
capacitor bank and the MOV. The bypass and overvoltage protection system will be
modeled using ATP.
2.0 Project Status
2.1 Subsystems
For an efficient solution to protect the capacitor bank and the MOV of the AMPS,
it is helpful to modularize the problem in list of simple tasks or subsystems, rather than
tackling it as a whole. For that very reason, this project is modularized into four
subsystems viz. breaker subsystem, thyristor circuit subsystem, sensing subsystem, and
microcontroller subsystem. Special consideration will be taken for MOV selection. A
functional block diagram of the project development status can be seen in the appendix.
The completed areas of the diagram have been shaded. The unshaded areas are either
currently being worked on or yet to be started.
2.1.1 Breaker Subsystem
This subsystem employs a three-pole breaker that is actuated by a 120VAC main
coil. A solid state relay is used to control current flow to the coil. When a 5VDC signal
is sent from the microcontroller to the relay, the relay completes the breaker main coil
6
circuit. This in turn closes the main contacts. Each pole of the breaker’s main contacts
will be connected in parallel with one phase of the capacitor bank. Therefore closing the
breaker shorts the capacitor bank out of the transmission line. The breaker will reopen
after a delay period designated by the user during initialization. If the fault condition still
remains, the breaker will again close and remain closed until reset.
This subsystem was tested using the procedure given in the validation section of
this report. The data in Table 1 of the appendix was obtained using a solid state relay
borrowed from another project due to delayed delivery of our intended relay. When the
correct relay arrives, the test procedure will be repeated and the data given in this report
will be replaced by the new information.
Using the loaned relay, the bypass breaker subsystem fell well within
specifications.
2.1.2 Thyristor Circuit Subsystem
The purpose of this subsystem is to rapidly reduce the flow of current through the
series bypass capacitor if the MOV protection system, which is described below, begins
to exceed its power handling capability. The thyristor circuit is connected in parallel with
the MOV and the breaker subsystem. This provides a low resistance path like the breaker
but is much faster to turn on when activated. Most of the current will then be diverted
past the MOV and bypass capacitor if a fault condition causes line current in excess of
specifications. The thyristor circuit can then be disabled quickly and the line put back in
normal operation if the fault condition clears limiting disruption of the line.
The thyristors are a special kind of power semiconductor device that when placed
in anti-parallel acts like a bi-directional high-speed switch. A thyristor is similar to a
diode except it has an additional terminal called a gate. Without a gate current the
7
thyristor can conduct if the voltage between the anode and cathode exceeds the breakover
voltage VBO. The gate current lowers the breakover voltage allowing control over when
the thyristor conducts. Once triggered into the on condition, the thyristor stays on until
load current drops below the holding current IH. By connecting two of these devices
together in parallel but opposite in polarity to each other, alternating current can be
controlled when the gates are properly triggered.
A firing board that is purposely built for this function controls the gate circuit and
provides the rated gate current pulse and timing for each device. This board is controlled
by a low voltage dc signal and provides isolation from the output voltage to protect
sensitive control circuitry. The firing board is an expensive component of this project, so
to reduce cost and complexity we are currently exploring replacing the firing board and
discrete thyristors with solid state relays that include the thyristors, firing circuitry, and
isolated dc control all in a relatively small encapsulated package.
2.1.3 Sensing Subsystem
A sensing subsystem is a must for the AMPS. This is the subsystem that detects
the overvoltage across and current through the capacitor. Isolated transducers will
measure the voltage across and the current through the capacitor. The transducer outputs
will feed the input ports of the microcontroller board. These signals will help
microcontroller take the necessary action to protect the MOV and the capacitor bank
during a fault condition. The current transducer is connected in series with the capacitor
bank, while the voltage transducer is connected in parallel with the capacitor bank and
the MOV. Their outputs enable microcontroller to get desired parameters for the
necessary calculation and initiate corresponding action.
8
A couple of current transducers (LEM model: LT 100-P, and LT 100-S), and a
voltage transducer (LEM model: LV 100) have been donated to this project. Testing the
available transducers to check if they are suitable for the AMPS is yet to be done.
Looking at the data sheet of the respective transducers, both types of current transducers
will work well for the AMPS, while there is a slight doubt on voltage transducers due to
its primary voltage rating (100…2500V), though the AMPS operates above 120VAC. In
an event that the given voltage transducer is not suitable for the AMPS, other options will
be explored. Testing and making sure that the transducers are suitable for measuring the
voltage across and the current through the capacitor bank is the next step in this project.
The transducers’ output should be compatible with the Analog to Digital Converter of the
microcontroller board.
2.1.4 Microcontroller Subsystem
The microcontroller will be the brain of this project. The microcontroller will
have an initialization menu to allow a user to set specific system parameters. After the
desired capacitance and menu options have been selected, sensing inputs will be provided
to the microcontroller so it can monitor the system. Several setpoints will be calculated
for the segmented capacitance so the microcontroller knows when to signal the thyristors.
The microcontroller outputs will control the thyristor firing circuit board and the solid
state relay for the breaker bypass system. When the microcontroller senses a designated
current value through the capacitor bank, it will begin conducting continuous MOV
energy calculations. When a setpoint is reached that designates possible damage to the
MOV, the thyristors will be triggered to bypass the MOV and the capacitor bank. If the
thyristors fail to reduce the current across the capacitor bank, the microcontroller will
send a signal to close the bypass breaker.
9
2.1.5 Metal Oxide Varistor (MOV)
The metal oxide varistor (MOV) is connected in parallel with the series capacitor
and is used to limit high energy, short duration overloads to the capacitor. A MOV is a
special kind of non-linear resistor that changes from a high resistance state to a low
resistance state as the voltage across it exceeds its normal operating voltage. As the
voltage across the MOV increases its current carrying capacity also increases. The MOV
parameters include a minimum and maximum varistor voltage VNOM that outlines the
beginning conduction region. MOVs are also separated by their physical diameter, which
is a direct representation of their peak current parameter. Finally, MOVs have a
maximum voltage parameter called the clamping voltage, which is designed into the
device when manufactured. This voltage is the maximum voltage the connected circuit
can see when the MOV is forced to its maximum rated current.
3.0 Method of Solution
3.1 Technical Description
ATP will be used to simulate our design. Two schematic diagrams and their
simulated plots are attached in the appendix, Figures 5 & 6. The schematics represent a
single phase of the AMPS. The diagram in Figure 5 shows the system with the MOV
excluded. The multiple paths utilized to bypass the series capacitance can clearly be seen
in Figures 5 & 6. Charts 1 & 2 illustrate what happens to the system when the thyristors
activate and when the breaker closes. The red waveform on the left side of both Charts 1
& 2 represents the voltage across the capacitor. The blue and green waveforms represent
the current through the thyristors and the purple waveform represents the current through
the bypass breaker. The activation of the thyristors removes the voltage, red wave, across
the capacitor protecting it from potentially high voltage that could cause damage. The
10
switch represents the bypass breaker, which only actuates if the thyristors fail, but for the
purpose of simulated results it is set to activate at 0.2 seconds. When the switch is closed
it bypasses everything, this is demonstrated as the blue and green thyristor currents go to
zero and the purple breaker current picks up where they dropped off. Unfortunately the
bypass breaker is not fast enough to protect the capacitor during a fault. A fault generates
a high current very rapidly and this current can damage the capacitor in the time it takes
the breaker to close, so a MOV is added to absorb that initial current.
Figure 6 is a schematic drawing with the MOV included and is associated with
Chart 2. The MOV is active from the start of the Figure 6 simulation, which explains the
lower capacitor voltage amplitude when compared to Chart 1. The affects of the MOV
on the system are dramatic when comparing Figures 7 and 8. The rest of the system is
unaffected by the insertion of the MOV.
3.2 Theoretical Basis and Fundamental Relationships
The design sequence is peripherally based, meaning most microcontroller support
systems will be developed prior to the microcontroller itself. As mentioned previously,
the system will be modeled using the ATP simulation program. Subsystems that can be
tested without the microcontroller will be built first to confirm valid signal waveforms.
For instance, the microcontroller has set input and output tolerances so valid signal
confirmation is necessary for proper transducer implementation.
4.0 Validation
4.1 Test Plan (Specifications and Metrics)
•
Test Procedure for the Bypass Breaker Subsystem:
1. Connect microcontroller to control side of the solid state relay.
2. Connect load side of the solid state relay to 120VAC plug and breaker main coil.
11
3. Apply 5.0VDC across the breaker main contacts using a power supply and current
limiting resistor (510Ω).
4. Load Rabbit toggle program into microcontroller.
5. Attach the oscilloscope probe (#1) to the Rabbit microcontroller PORT F.2.
6. Attach the other oscilloscope probe (#2) across the breaker main contacts.
7. Adjust oscilloscope to obtain both signals clearly.
8. Setup oscilloscope to obtain a reading.
9. Cycle breaker by toggling the microcontroller using Button 2.
10. Close breaker and then reopen breaker after about 1 second.
11. Press Run/Stop button on oscilloscope to capture data.
12. Use oscilloscope cursors to read minimum and maximum closing time.
13. Record data.
14. Use oscilloscope cursors to read opening time.
15. Record data.
•
Test Procedure for the Thyristor/Relay Subsystem:
The testing procedure for the thyristor/relay subsystem will be similar in form to the
bypass breaker subsystem test procedure. The difference is the requirement to test the
thyristors for proper operation under loaded conditions. To conduct a test that is
comparable to actual operating conditions the AMPS will be used.
1. Connect thyristors and firing circuit in parallel with series capacitor in one phase of
AMPS.
2. Connect microcontroller, which has been loaded with the software used to toggle
firing circuit on and off.
12
3. Configure line impedance to limit current through the capacitor (Maximum of 6
amps).
4. Connect an Agilent 54622D oscilloscope to measure firing circuit drive voltage and
voltage across the series capacitor by using a transducer that will prevent a ground
loop condition that could harm the oscilloscope.
5. Connect a clamp on digital current meter in series with the phase being used for
testing to confirm line current.
6. Turn on AMPS and ensure that no fault conditions are set to occur.
7. Measure and record line current.
8. Set oscilloscope time base to 1 sec/division.
9. Push microcontroller switch to toggle the firing circuit drive voltage.
10. Capture and record the waveform of the drive circuit and voltage across the capacitor.
11. Measure thyristor shorting and dropout times.
12. Record data.
13. Measure voltage drop across thyristor to measure conduction impedance.
14. Record data.
•
Test Procedure for the Sensing Subsystem:
The sensing subsystem will be tested first to make sure the output is compatible with
the microcontroller analog to digital converter. After the compatibility is satisfied, the
microcontroller conversion of the sensed parameter will be compared with the actual
parameter.
13
•
Test Procedure for the Microcontroller:
•
Test Procedure for the Board
1. Assemble the microcontroller, download sample code, run sample code, and
compare to the written results in the manual for first use.
2. Downloaded test code to board that toggles a pin for sending signals to relays.
3. Download test code to board that outputs a simple menu to test LCD screen and
the toggles LEDs on the keypad.
4. Connect a function generator to test the analog to digital converter. A LCD
readout of the converted signal will be compared to a measured quantity of the
signal.
•
Test Procedure of the Code
1. Download code designed for our project
2. If the code is written correctly an option menu will be displayed on the LCD
asking to select capacitance level being used and delay period for reinserting the
capacitor bank.
3. Connect the oscilloscope to pins that are signaling relays to capture signal and
response time.
5.0 Results
5.1 Operating Procedures
At this time there are no operating procedures. The operating procedures will be
developed in conjunction with the microcontroller subsystem. These procedures will
encompass initialization of system variables, connection of the COPS to the AMPS, and
the segmented capacitance configuration.
5.2 Validation Results
14
Minimum closing time (marked to the first bounce):
•
Maximum closing time: 13.9 ms
•
Average closing time:
12.088 ms
Maximum closing time (marked to the last bounce):
•
Maximum closing time: 20 ms
•
Average closing time:
18.488 ms
Opening time for the Bypass Breaker:
•
Maximum opening time: 15.08 ms
•
Average opening time:
12.896 ms
Note: Five data sets were taken.
15
5.3 Cost analysis
Labor costs included in the cost analysis, Table 1, are purely fictional and
included in the analysis only for budget realism. Professor Herbert Hess has donated the
firing circuit board and circuit breaker to the project. The Bill of Materials, which can be
seen as Table 2 in the appendix, shows that we have already paid for the microcontroller
with development kit, one solid state relay, and a few small items. We have currently
only used 35 percent of the budget allocated for the project.
Table 1: Estimated Budget
Labor Costs:
Chris Butterworth
Michael Dole
Randy Mallo
Prasanna Upadhyaya
Total Labor Costs:
Equipment Costs:
Thyristor Firing Board
Printed Circuit Board
Metal Oxide Varistor
Microcontroller
Circuit Breaker
Thyristors
Poster
Cart
Miscellaneous
Total Costs:
Grand Total:
Actual
Donated
Volunteer
$ 4,125.00
$ 4,125.00
$ 4,125.00
$ 4,125.00
$16,500.00
$265.00
$250.00
$ 25.00
$249.64
$200.00
$
$
$
$
15.00
45.00
80.00
75.00
$739.64
$465.00
16
$16,500.00
$17,704.64
6. Bibliography
[1]
Elneweihi A.F, Hydro B.C. “Excerpts from the IEEE Publication on Series
Capacitor Bank Protection.” (1998): p1-18.
[2]
Microprocessors and Development Kits. Rabbit Semiconductor. March 6, 2005.
<www.rabbitsemiconductor.com>
17
APPENDIX
18
a. Electrical and Physical Specifications:
Maximum Current Allowed to the Capacitor:
10Amps
Breaker Maximum Closing Time:
<2 Cycles
(<33.3ms @ 60Hz)
Breaker Maximum Opening Time:
<3 Cycles
(<50ms @ 60Hz)
Breaker Continuous Current Capability
>20 Amps
Thyristor Maximum Shorting Time:
<½ Cycle
(<8.33ms @ 60Hz)
Thyristor Maximum Dropout Time:
<1 ¼ Cycle
(<20.8ms @ 60Hz)
Thyristor Continuous Current Capability:
>20 Amps
Junction Temperature:
<100˚C @ Room Temp. 50 to 85˚F
Functional Specifications:
Successfully protect the capacitor bank during a fault situation
Successfully protect the MOV before damage occurs
Reinsert the capacitor bank after a user designated delay period
Contain a backup action in the event the primary protective action fails
Reasonably portable
Connect and disconnect from AMPS without disrupting existing equipment
Use existing instrumentation to record and evaluate performance
Use existing equipment for fault initiation
Platform existing that allows the user to designate the closing delay contact period and
the percentage of the monitored capacitor bank that is inline.
COPS Ratings:
Nominal Voltage:
120VAC (Line to Neutral)
Nominal Frequency:
60 Hz
19
b. Bill of Materials
Table 2: Bill of Materials
Component:
Unit Price
Microcontroller Development Kit
$ 239.00
Solid State Relay
$ 15.68
Light Switch Assembly
$
6.85
AMPS Diagrams
$
4.67
Totals
$ 266.20
Shipping
$ 10.64
$ 6.70
$
$
$ 17.34
$ 283.54
Grand Total:
20
c. Test Information:
Equipment Used for Test Procedure:
1. Agilent 54622D 100 MHz Oscilloscope
2. Fluke 45 Dual Display Multimeter
3. Hewlett Packard E3610A DC Power Supply
Table 3: Breaker Test Data
Data Set
1
2
3
4
5
Average
Closing Time (ms)
Min
Max
13.900
20.000
10.600
19.400
11.700
17.600
11.000
17.080
13.240
18.360
12.088
18.488
Opening Time (ms)
11.240
15.080
14.900
14.000
9.260
12.896
Figure 1: Example Minimum Rise Time Waveform
21
Figure 2: Example Maximum Rise Time Waveform
Figure 3: Example Fall Time Waveform
22
d. Design Project Status Diagram
Figure 4: Functional Block Diagram Representing Project Status
Problem Definition
Conceptual Design
Design
Breaker
Bypass
Subsystem
Design
Thyristor
Circuit
Subsystem
Design
Sensing
Subsystem
Design
Microcontroller
Subsystem
Construct
Breaker
Bypass
Subsystem
Construct
Thyristor
Circuit
Subsystem
Construct
Sensing
Subsystem
Construct
Microcontroller
Subsystem
Test
Breaker
Bypass
Subsystem
Test
Thyristor
Circuit
Subsystem
Test
Sensing
Subsystem
Test
Microcontroller
Subsystem
Document
Breaker
Bypass
Subsystem
Document
Thyristor
Circuit
Subsystem
Document
Sensing
Subsystem
Document
Microcontroller
Subsystem
Integrate All Subsystems Together
Organize Final Project Documentation
Present Final Product
23
e. Schedule:
The project got off to a slow start but the group was able to make up time and
finish the semester as expected. In fact, the project is slightly ahead of schedule due to
work that was done concerning the firing subsystem. The group will continue to work as
actively as possible during the summer. At the beginning of the fall semester, work will
recommence on the sensing, firing, and microcontroller subsystems. There has been a
slight alteration of the schedule that was proposed. The microcontroller subsystem is
now slotted to be complete October 28th to allow additional time for integration of all of
the subsystems.
Spring Semester (2005)
Start Breaker Bypass Subsystem
Complete Breaker Bypass Subsystem
Start Sensing Subsystem
Start Microcontroller Subsystem
Project Report
March 21
April 1
April 4
April 11
May 9
Fall Semester (2005)
Start Firing Subsystem
Complete Firing Subsystem
Complete Sensing Subsystem
Complete Microcontroller Subsystem
Complete Integration of Subsystems
Document Project to Complete the Design
Present Final Report and Documentation
August 22
September 9
October 7
October 28
November 18
December 2
December 5-9 (Dead Week)
24
Figure 5: ATP Project Diagram with MOV Excluded
BYPASS
B6
OFF
FIRE
ON
BYPASS
FIRE
CA2
AN1
FIRE
VSRC
B2
B1
B3
B5
B6
U
Figure 6: ATP Project Diagram with MOV Included
BYPASS
B6
OFF
FIRE
FIRE
BYPASS
ON
CA2
AN1
FIRE
MOV1
VSCR
B1 B1
B2
B3
B7
U
25
Chris Butterworth
Individual Report
Specific Contributions:
•
Presented the idea for the bypass breaker subsystem to the group after discussing
technical ideas with Eric Bakie.
•
Researched both electromechanical and solid state relay options for the bypass
breaker subsystem.
•
Obtained some donated equipment for bypass breaker and thyristor subsystems.
•
Developed testing procedure that was used for the breaker subsystem and used as a
basis for the thyristor subsystem.
•
Ordered solid state relay for bypass subsystem.
•
Responsible for keeping track of budget and spending.
•
Conducted research on MOVs including figuring out what characteristics are
important to our project.
•
Initiated contact with several manufacturers and distributors to obtain MOVs. So far
we’ve gotten 3 samples of various sizes we can test.
•
Made copies of the AMPS diagram for each group member to use as reference.
•
Obtained poster quote information.
•
Strong contribution to project paperwork.
•
Developed a draft of specifications for proposal to the group.
•
Identified the contact from whom Prasanna obtained the LEMs.
26
Prasanna Upadhyaya
Individual Report
• With blank knowledge about the metal oxide varistor (MOV), and thyristors I tried to
stay active trying to find solution for the protection of the capacitor bank of the
Analog Model Power System (AMPS) in BEL G10 from overvoltage.
•
Michael and I checked prices for the possible components that we were going to use
like MOV, current and voltage transducer, firing system (thyristor) board, and
microcontroller.
•
I am responsible for the sensing subsystem portion of the design project.
•
Discussed to name our team and finalized to be represented as Design COPS.
•
Discussed the requirements of transducers (both current and voltage) for the AMPS.
•
Researched on transducers on the basis of those requirements and decided to get
transducers from LEM, USA.
•
Decided to use HAW 20-P for current transducer and CV 3-500 for voltage
transducer
•
Acquired spare LEMS from Greg Klemesrud down from the GJ Power Laboratory.
Got LT 100-P, and LT 100-S model for current transducers, and LV 100 for voltage
transducers. I researched on those transducers and decided that we could use both
type of current transducers for our system, but we have to do some testing before we
decide on using the voltage transducer because of its primary voltage rating
(100…2500V), though AMPS operates above 120V.
•
I was actively involved in making suggestions and decision in our team project. I was
active to make presentation slides for the presentation as well as help writing final
report for the semester. I took part in prototype demonstration as well as taking the
measurement before the demonstration.
27
Randy Mallo
Individual Report
Microcontroller
•
•
•
•
What the microcontroller has to do: like read a sensor, trip a relay, ect…
What board would be best to do the tasks needed
The cost of that board and what comes with the board
Then ordered the board
ATP Program
•
•
•
•
•
•
Worked on a schematic drawing with general parameters
Simulated it and charted the results
Showed what I had done at the Demo
Continuing learning of ATP Program
Organized meeting times and places to meet
Tried to organize what was to be done at meetings
28
Michael Dole
Individual Report
ƒ
Participated in the conceptual design process and when new problems were
discovered.
ƒ
Initially found LEM information and pricing until Prasanna took over the sensing
transducers system.
ƒ
I volunteered to continue designing the thyristor bypass circuit and select
components for its use.
ƒ
Presented a new idea for the thyristor system after researching firing board and
thyristor availability and price. I have modified the original design concept of a
firing board driving discrete thyristors to that of a simpler and cheaper solid state
relay design. Thyristor bypass is the next focus of our team after summer break.
ƒ
Made slides for and participated in the creation of the design review power point
presentation
ƒ
Purchased a switch box, switch, and assorted mounting parts for the bypass
breaker system and assisted in its preparation for the initial test and
demonstration.
ƒ
Developed an idea of how to sense the current thru the capacitor and power
dissipated in the MOV using only one current and voltage LEM. This idea was
initially dismissed, but may now be incorporated into the design because of a
change in sensing specifications.
ƒ
Have installed and am learning to run the ATP program to simulate the current
and voltage conditions the thyristors will need to operate under.
ƒ
I have enjoyed working with all of my team members. I think each of us have
skills that complement each other and have made this project easier to complete
so far.
29