Gcsc gto thyristor controlled series capacitor

gcsc
seminar

1. GCSC - GTO Thyristor controlled series capacitor Presented by Leo paul chittilappilly

2. INTRODUCTION Proposed by Karady & others in 1992. It consists of Fixed capacitor in parallel with anti parallel GTO pair or valve. Thyristor valve has the capability to turn on and turn off mechanism. Act as a dual of TCR.

3. BASIC SCHEME OF GCSC

4. The GCSC controls the voltage across the capacitor ( Vc ) for a given line current. when the GTO is closed the voltage across the capacitor is zero when the GTO is open the voltage across the capacitor is at its maximum value The magnitude of the capacitor voltage can be varied continuously by the method of delayed angle control For practical applications, the GCSC compensates either the voltage or reactance

5. working Closing and opening of valve is carried out in each half cycle in synchronism with supply frequency. Turn off instant of each half cycle is controlled by a delay angle ᵞ wrt peak of line current. Here ᵞ varies from 0 to 90 degrees. Line current i and Vc are shown for ᵞ =0 and at an arbitary value of ᵞ

6. principle of turn-off delay angle control

7. Variation of VCF is normalized to maximum voltage GCSC can be operated in either to control Voltage or reactance Fundamental component of the series capacitor voltage vs. the turn-off delay angle γ .

8. GCSC in voltage compensating mode GCSC can be operated either to compensate voltage or to compensate Xc (ᵞ). In first case, GCSC is used to maintain the rated compensating voltage in association with decrease of line current over an interval I min ≤ I ≤I max n this case, Xc is selected in such a manner that Vc max/I min = Xc . When I is increased from I min to I max, ᵞ is also increased

9. GCSC in reactance compensating mode GCSC is used to maintain the max rated compensating reactance at any line current up to max. In this case, Xc is selected in such a manner that Vc max/I max = Xc . GCSC can be used to vary Xc from 0≤ Xc ( ᵞ) ≤ Xc

10. Thank you