First Generation of FACTS

8/2/2019 First Generation of FACTS

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FACTS Devices


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There are two generations for realization of power

electronics-based FACTS controllers.

The first generation has resulted in the Static VAR

Compensator (SVC), and the Thyristor- Controlled

Series Capacitor (TCSC).

The second generation has produced the Static

Synchronous Compensator (STATCOM), the StaticSynchronous Series Compensator (SSSC), and the

Unified Power Flow Controller (UPFC).


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Thyristor-Controlled Series Capacitor

(TCSC)


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Location of TCSC in power system

It has been proven that the mid-point of

transmission line is the optimal location of

TCSC. But the optimal position to connect a

TCSC is at the sending end where there is

reactive power to be compensated.


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Circuit components

Series fixed capacitor (FC)

Thyristor controlled reactor (TCR)


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Practical Module


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Mov : A metal-oxide varistor.

Ld : A current limiting inductor.

UHSC : An ultra high-speed contact.


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Modes of TCSC Operation

1- Bypassed-Thyristor Mode.

2- Blocked-Thyristor Mode.3- Partially Conducting Thyristor, or Vernier,

Mode.


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Advantages of TCSC

Rapid and continuous control of the

transmission-line series-compensation level.

Dynamic control of power in selected

transmission lines within the network to enable

optimal power conditions and prevent the loop

of power.

Damping of the power swings from local and

inter-area oscillations.


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Suppression of sub synchronous oscillations.

Enhanced level of protection for series

capacitors.

Reduction of the short-circuit current.


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Disadvantages


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Static VAR Compensator (SVC)


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Static VAR Compensator (SVC)

It is an electrical device using power electronics for

providing fast acting reactive power on high voltage

electricity transmission networks. The term "static"refers to the fact that the SVC has no moving parts

(other than circuit breakers and disconnects, which do

not move under normal SVC operation), so it requires

low maintenance. It is connected in shunt with the

power system.
http://en.wikipedia.org/wiki/Circuit_breakerhttp://en.wikipedia.org/wiki/Circuit_breaker


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Circuit components


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1. Step down transformer

2. Medium voltage switches gear.

3. Compensation reactor.

4. Thyristor valves converter.5. High order harmonics filtering device (capacitor

banks).

6. water cooling system .7. Full digital control system.


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Principles of operation

The SVC regulates voltage at its terminal bycontrolling the amount of reactive power injectedinto or absorbed from the power system. When

system voltage is low, the SVC generates reactivepower (SVC capacitive). When system voltage ishigh, it absorbs reactive power (SVC inductive).The variation of reactive power is performed by

switching three-phase capacitor banks andinductor banks connected on the secondary side ofa coupling transformer.


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Location of SVC in power system

It has been proven that the mid-point of

transmission line is the optimal location of

SVC. This proof is based on the linear load

which is not valid practically. For non-linear

load model it was found that the best location

for advanced static var compensator close to

the receiving end where a wide range ofreactive power could be controlled.


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Advantages of SVC

1. Cheaper2. Higher capacity

3. Faster & more reliable

4. Simple operation

5. Improve steady state stability & transient stability

6. Voltage regulation

7. Reduce transmission losses

8. Increase power transfer capacity


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Disadvantages of SVC

Same degradation in reactive capability asvoltage drops as capacitors.


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The problems solved with SVC

1. Harmonics.

2. The need for additional reactive power.

3. Voltage fluctuation.

4. Unbalanced loads.

5. Rapid changes in reactive power.

6. Power oscillation.


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Benefits


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How Static var compensator different

from other FACT devices

Static Var Compensators are the most important

FACTS devices; SVC's have high accuracy,

availability and fast response and therefore give bettersteady state and transient voltage control compared to

classical shunt compensation. SVC's require large

inductive and capacitive components and occupy a

larger space than STATCOMs. STATCOMs givehigher reactive outputs at low voltages compared to

SVCs.

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First Generation of FACTS