This document describes the fixed capacitor thyristor controlled reactor (FC-TCR), which uses a fixed capacitor and thyristor controlled reactor (TCR) to maintain the desired voltage at a high voltage bus. It contains the circuit diagram and operating characteristics of the FC-TCR, explaining how the capacitive VAR output of the fixed capacitor can be opposed by the inductive VAR output of the TCR through firing delay angle control. It also discusses how losses in the FC-TCR can be minimized by switching the fixed capacitor using mechanical breakers.

1. FC-TCR
Prepared By :
Upadhyay Rakshita R .
Er No : 140370707018
Roll no : 24

2. Contents…
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 Introduction
 Circuit diagram
 Operating characteristics
 Losses in FC-TCR
 Conclusion
 References

3. Introduction
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 Objective : To maintain the desired voltage at a high
voltage bus.
 FC-TCR is a var generator arrangement using a
Fixed capacitance with a TCR.
 The current in the reactor is varied by the method of
firing delay angle control method. (Qc) of the fixed
capacitor is opposed by the (QL) of the TCR.

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 Capacitive var output :
1) By increasing current in TCR lead to decrease in output.
2) When TCR is off results in max var output.
 Zero var output :
1) cancelling var by equalling both capacitive and
inductive current.
 Inductive var output :
1) further increase in current lead to increase in output.

5. Circuit diagram:
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 Components :
1) A TCR
2) A fix capacitor across TCR
3) High pass filter

6. Operating characteristics :
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 Without stepdown transformer :
1) ISVC =VJ BSVC ,where BSVC =BC+BTCR
2) By dimensioning the ratings of the TCR and the
capacitor, respectively, the production and absorption
ranges can be selected according to the system
requirements.

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 With stepdown transformer :
1) BSVC= Bσ(BC+BTCR)/(Bσ+BC+BTCR )
2) BSVC MAX = (1-BC/Bσ)*BC (at α = 180˚)
3) BSVC MIN = (1-(BC+BL)/Bσ)*(BC+BL) (at α = 90˚)

8. Losses in FC-TCR
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 Circulation of large current for cancelling capacitive var
resulting high steady state losses.
 Losses can be minimized by switching the fixed
capacitors through mechanical breakers, ensuring that the
capacitors are inserted in the compensator circuit only
when leading vars are needed.

9. Conclusion
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 FC-TCR is useful for getting controllable range of var
output with a capacitor connected across TCR. And
losses can be minimized by switching the fixed capacitor
by mechanical breakers.

10. References
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 ‘Thyristor-based FACTS controllers for Electrical
Transmission Systems,’ R. Mohan Mathur, R K Verma,
Wiley IEEE Press
 ‘Reactive power control using FC-TCR’,Ms shilpa gupta,
IJITR,volume-1,january-2013,india

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