FACTS (1)

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FACTS Flexible AC Transmission System

Presented by: Dr Ahmed Massoud

Dr Ahmed Massoud University of Strathclyde 1

FACTS

1. POWER SYSTEMS 2. FACTS definition 3. FACTS controllers 4. Parallel controllers 5. Series controller 6. Series-parallel controllers 7. HVDC 8. Others Dr Ahmed Massoud University of Strathclyde 2

POWER SYSTEM

GENERATION TRANSMISSION DISTRIBUTION Dr Ahmed Massoud University of Strathclyde 3

Characteristics of Transmission Bottlenecks

• • • • •

Steady-State Power Transfer Limit Voltage Stability Limit Transient Stability Limit Thermal Limit Short-Circuit Current Limit

Dr Ahmed Massoud University of Strathclyde 4

Conventional System Solutions to enhance Transmission capability

• • • • •

Series Capacitors (X) Switched Shunt-Capacitor and Reactor (V) Transformer LTC’s (V) Phase Shifting Transformers (

δ

) Synchronous Condensers (V)

Dr Ahmed Massoud University of Strathclyde 5

FACTS

1. POWER SYSTEMS 2. FACTS definition 3. FACTS controllers 4. Parallel controllers 5. Series controller 6. Series-parallel controllers 7. HVDC 8. Others Dr Ahmed Massoud University of Strathclyde 6

F A C T

Systems (FACTS)

FACTS AC transmission systems incorporating the power electronic-based to enhance controllability and increase power transfer capability.

FACTS Controllers A power electronic based system & other static equipment that provide control of one or more AC transmission parameters.

Dr Ahmed Massoud University of Strathclyde 7

Power Electronics Devices For FACTS Controllers

• • •

Line-Commutated Thyristors Electrically Triggered (ETT) Light Triggered (LTT)

• • •

Self-Commutated Gate-Turn Off Thyristors (GTO) Insulated Gate Bipolar Transistors (IGBTs) Integrated Gate Commutated Thyristors (IGCTs)

Dr Ahmed Massoud University of Strathclyde 8

FACTS

1. POWER SYSTEMS 2. FACTS definition 3. FACTS controllers 4. Parallel controllers 5. Series controller 6. Series-parallel controllers 7. HVDC 8. Others Dr Ahmed Massoud University of Strathclyde 9

F A C T S c o n tro lle rs lin e c o m m u ta te d

S e rie s

thy ris to r c o ntro lle d s e rie s c a pa c ito r (TC S C )

B a c k -to -b a c k

c o nv e ntio na l HVD C

S h u n t

thy ris to r c o ntro lle d re a c to r o r s w itc he d c a pa c ito r (TCR or TS C)

S e rie s -s e rie s

inte rline po w e r flo w c o ntro lle r (IP F C )

fo rc e d c o m m u ta te d

S e rie s

static synchronous series com pensator (S S S C )

S h u n t

s ta tic s y nc hro no us c o mpe ns a to r (S TATC O M )

S h u n t-S e rie s

unifie d po w e r flo w c o ntro lle r (UP F C ) B a tte ry e ne rgy s to ra ge (B E S S )

S e rie s -s e rie s

inte rline po w e r flo w c o ntro lle r (IP F C ) S upe rc o nduc ting M a gne tic E ne rgy S to ra ge (S M E S ) Dr Ahmed Massoud University of Strathclyde

B a c k -to -b a c k

light HVD C 10

___

V s X P

=

s X r

sin δ δ

V s

I.X

V r

I

___

V r

Dr Ahmed Massoud University of Strathclyde 11

Controllable parameters

Control of the line impedance

current and active power control

Control of angle

current and active power control

Series voltage injection

Current, active, and reactive power control

Parallel voltage injection

Current, active, and reactive power control Dr Ahmed Massoud University of Strathclyde 12

Series control

V 1 X series X V 2 V series

P=V

1

.V

2

.sin(

δ

)/(X-X

s e rie s

)

Dr Ahmed Massoud δ University of Strathclyde

I V 1 V 2

13

V 1

Parallel control

X V 2 Q P= V 1 .V

2 .sin(

δ

)/X

Dr Ahmed Massoud δ University of Strathclyde

V1 I I V 1

14

V 2

Series and parallel control

V 1 X series X V 2 V series Q

Dr Ahmed Massoud University of Strathclyde 15

FACTS

1. POWER SYSTEMS 2. FACTS definition 3. FACTS controllers 4. Parallel controllers 5. Series controller 6. Series-parallel controllers 7. HVDC 8. Others Dr Ahmed Massoud University of Strathclyde 16

Static VAR compensator

• • • • • • •

TCR = Thyristor Controlled Reactor TSR = Thyristor Switched Reactor TSC = Thyristor Switched Capacitor MSC = Mechanically-Switched Capacitor MSR = Mechanically-Switched Reactor FC = Fixed Capacitor Harmonic Filters

Dr Ahmed Massoud University of Strathclyde 17

Thyristor Controlled Reactor (TCR)

Parallel-connected static var generator or absorber ● Output is adjusted to exchange capacitive or inductive current ● Maintain or control specific parameters of the electrical power system (typically bus voltage).

● ● Thyristor-based Controllers Lower cost alternative to STATCOM Dr Ahmed Massoud University of Strathclyde 18

8 6 4 2 0 -2 -4 -6 -8 Voltage Current 0.005

0.01

Time (s) 0.015

Firing angle of 90

0.02

1 0.667

0.333

0 -0.333

-0.667

-1 0 0.005

0.01

Time (s) 0.015

Firing angle of 135

0.02

Dr Ahmed Massoud

Thyristor Controlled Reactor

University of Strathclyde 19

Thyristor Switched Capacitor (TSC)

Dr Ahmed Massoud University of Strathclyde 20

Static Synchronous Compensator (STATCOM)

● Parallel-connected static var compensator ● Capacitive or inductive output current controlled independently of the ac system voltage 21 Dr Ahmed Massoud University of Strathclyde

Inverter

(IGBT, GTO, or GCT)

L Q V

dc Dr Ahmed Massoud

P

(if no energy source is provided) University of Strathclyde 22

Parallel Active Power Filters (Parallel APF)

• Reactive power • Compensation • Source current’s higher • Harmonics compensation • DC element voltage control Dr Ahmed Massoud University of Strathclyde 23

3-phase supply

i s e i L i f L v

Shunt active filter non-linear load Shunt active power filter single line diagram Dr Ahmed Massoud University of Strathclyde 24

i dc (t) v dc (t)

+ _ C S a

v an

S b S' a

v bn

S' b S c

v

S' c

cn

L a L b L c

i a i b i c e a e b e c

Two level voltage source inverter Dr Ahmed Massoud University of Strathclyde 25

Dr Ahmed Massoud University of Strathclyde 26

Voltage source inverters

1. Two level Voltage source inverter 2. Multilevel voltage source inverter 3. Series connection Current source inverter ?

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Multilevel inverter

1. Neutral point clamped 2. Cascaded 3. Flying capacitor Dr Ahmed Massoud University of Strathclyde 28

Neutral point clamped

Dr Ahmed Massoud University of Strathclyde 29

Flying capacitor

Dr Ahmed Massoud University of Strathclyde 30

Cascaded

Dr Ahmed Massoud University of Strathclyde 31

E S1 S4 S5 E S8

i load >0

Dr Ahmed Massoud

2E volt

D1 i load E D4 2E D5 E

University of Strathclyde

i load <0

D8 i load 2E

32

E

E volt

i l o a d E i l o a d D 3 S 4 S 3 D 4 E D 5 S 5 E

i load >0

Dr Ahmed Massoud

S 8 E

University of Strathclyde

i load <0

D 8

33

E

E

0 volt

i l o a d E i l o a d D 3 S 4 S 3 D 4 0 E D 7 S 8

i load >0

Dr Ahmed Massoud

E

University of Strathclyde

S 7

i load <0

D 8

34

0

-E volt

i l o a d E E S 3 D 3 S 4 -E E D 7

i load >0

Dr Ahmed Massoud

D 6 E S 7

University of Strathclyde

i load <0

S 6 D 4 i l o a d

35

-E

-2E volt

D 2 i l o a d E S 2 E S 3 D 3 -2 E E D 7

i load >0

Dr Ahmed Massoud

D 6 E S 7

University of Strathclyde

i load <0

S 6 i l o a d

36

-2 E

Output of 5-level inverter (PWM)

3 -1 -2 -3 0 2 1 0 0 . 0 0 5 0 .0 1 T i me (s ) University of Strathclyde 0 .0 1 5 0 .0 2 Dr Ahmed Massoud 37

Series connection of IGBT

Dr Ahmed Massoud University of Strathclyde 38

Output of two-level inverter (PWM)

3 2 -1 -2 1 0 -3 0 0. 0 05 0 .0 1 T im e (s ) 0 .0 1 5 0 . 02 Dr Ahmed Massoud University of Strathclyde 39

FACTS

1. POWER SYSTEMS 2. FACTS definition 3. FACTS controllers 4. Parallel controllers 5. Series controller 6. Series-parallel controllers 7. HVDC 8. Others Dr Ahmed Massoud University of Strathclyde 40

Series Capacitors Applied For:

Increasing Power Transfer Increasing Stability Limits Improving Voltage Profile Improving Load Division

Dr Ahmed Massoud University of Strathclyde 41

Series Active Power filter (Series APF)

• Voltage harmonics compensation • Stability improvement • Current harmonics blocking 42 Dr Ahmed Massoud University of Strathclyde

Static Synchronous Series Compensator (SSSC)

● ● ● Output voltages in quadrature with, and controllable independently of, the line current Control the transmitted electric power.

May include energy storage to enhance the dynamic behavior of the power system by additional temporary real power compensation, to increase or decrease momentarily, the overall real (resistive) voltage drop across the line.

Dr Ahmed Massoud University of Strathclyde 43

Thyristor Controlled Series Capacitor (TCSC)

● Smooth control of series capacitive reactance Dr Ahmed Massoud University of Strathclyde 44

FACTS

1. POWER SYSTEMS 2. FACTS definition 3. FACTS controllers 4. Parallel controllers 5. Series controller 6. Series-parallel controllers 7. HVDC 8. Others Dr Ahmed Massoud University of Strathclyde 45

Unified Power Flow Controller (UPFC)

● A combination of STATCOM and SSSC coupled via a common dc link ● Bi-directional flow of real power between the SSSC and the STATCOM

Unified Power Flow Controller = Static Synchronous Series Compensator + STATCOM

Dr Ahmed Massoud University of Strathclyde 46

In v e r te r (I G B T , G T O , o r G C T ) S e r ie s c o n v e r te r C S h u n t c o n v e r te r L Dr Ahmed Massoud University of Strathclyde 47

Unified Power Quality Conditioner (UPQC)

• Source current harmonics compensation • System stability improvement • Reactive power compensation • DC element voltage control • Voltage harmonics compensation Dr Ahmed Massoud University of Strathclyde 48

Combination of active power filter and passive filter

Supply Load Active filter Passive filter Parallel active power filter and passive filter Dr Ahmed Massoud University of Strathclyde 49

Supply Load Passive filter Active filter Parallel active power filter in series with passive filter Dr Ahmed Massoud University of Strathclyde 50

Supply Active filter Load Passive filter Series active power filter and parallel passive filter Dr Ahmed Massoud University of Strathclyde 51

Supply Active filter Load Active filter Series and parallel active power filter (unified power quality conditioner UPQC) Dr Ahmed Massoud University of Strathclyde 52

Series VS. Parallel

● Series is more powerful in controlling the current/power flow and damp oscillations ● Parallel is more effective in voltage control and damping of voltage oscillations Dr Ahmed Massoud University of Strathclyde 53

FACTS

1. POWER SYSTEMS 2. FACTS definition 3. FACTS controllers 4. Parallel controllers 5. Series controller 6. Series-parallel controllers 7. HVDC 8. Others Dr Ahmed Massoud University of Strathclyde 54

FACTS and HVDC

Grid 1 V 1

FACTS or HVDC

V 2 Grid 2

Dr Ahmed Massoud University of Strathclyde 55

High voltage DC transmission (HVDC)

• • • It is economically attractive: over a long distance from a remote generating to the load centre (>300 miles) underwater transmission when connecting two AC systems at two different frequencies Dr Ahmed Massoud University of Strathclyde 56

• • • • • • • • • •

Advantages of HVDC

No limits in transmitted distance. Fast control of power flow, which implies stability improvements. Direction of power flow can be changed very quickly. HVDC can carry more power for a given size of conductor improved transient stability dynamic damping of the electric system oscillations Require less space compared to ac for same voltage rating and size Ground can be used as a return conductor No charging current HVDC transmission limits short circuit currents Dr Ahmed Massoud University of Strathclyde 57

Cost AC Cost DC Cost

Dr Ahmed Massoud

600-800Km

University of Strathclyde

Distance

58

The HVDC technology

The fundamental process that occurs in an HVDC system is the conversion of electrical current from AC to DC (rectifier) at the transmitting end, and from DC to AC (inverter) at the receiving end. 1. Natural Commutated Converters. The component that enables this conversion process is the thyristor (high power and low switching frequency).

2. Forced Commutated Converters. It uses GTO or IGBT. They are known as VSC (Voltage Source Converters). Dr Ahmed Massoud University of Strathclyde 59

HVDC transmission system

Terminal A Positive pole 12 pulse

Y Y

Δ

Y

L d

DC filter AC system A AC filter and power factor correction capacitors Y Y

Δ

Y

Negative pole 12 pulse

Dr Ahmed Massoud

DC filter

L d

University of Strathclyde

HVDC transmission line Terminal B AC system B

60

1.

2.

3.

Components of HVDC

Converter: at one side rectifier and the other inverter each converter consists of a positive pole and a negative pole each pole consists of 6 pulse converters connected through star-delta and star-star transformer to yield 12 pulse converter On the AC side: * AC filters to reduce the current harmonics generated from the converters * Power factor correction capacitors to supply the lagging reactive power On the DC side: smoothing reactor and DC filters to filter the ripple in the DC currents Dr Ahmed Massoud University of Strathclyde 61

12 pulse line frequency converter

Objectives: 1. Reduce current harmonics on AC side 2. Reduce voltage ripple on DC side 3. High power 12 pulse converter consists of two six-pulse converters connected through star-star and delta-star transformer The 2 converters are connected in series from the DC side and parallel from the AC side Dr Ahmed Massoud University of Strathclyde 62

i a i a1 2N:1 as1 i as1 cs1 n1 bs1 i a2

Dr Ahmed Massoud

i as2 as2 cs2 n2 bs2

University of Strathclyde

I d L d v d1 v d2

63

Types of HVDC links

1. Monopolar: Having one conductor and the ground is the return path

DC pole return earth

64 Dr Ahmed Massoud University of Strathclyde

2. Bipolar: There are two conductors (poles). One operates with positive polarity and the second with negative. During fault of one them, the bipolar acts as a monopolar

+ DC pole

Dr Ahmed Massoud

return earth - DC pole

University of Strathclyde 65

HVDC Light

1. HVDC Light unit sizes range from a few tens of MW to presently 350 MW and for DC voltages up to ± 150 kV and units can be connected in parallel.

2. HVDC Light consists of two elements: converter stations and a pair of cables. The converter stations are Voltage Source Converters (VSCs) employing Self-commutated switch 66 Dr Ahmed Massoud University of Strathclyde

FACTS

1. POWER SYSTEMS 2. FACTS definition 3. FACTS controllers 4. Parallel controllers 5. Series controller 6. Series-parallel controllers 7. HVDC 8. Others Battery Energy Storage System Super conducting material Dr Ahmed Massoud University of Strathclyde 67

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