FACTS Technology

1. Variable impedance type series
compensators
By: G A Chougule
EE, SITCOE

2. Index
• GTO Thyristor-Controlled Series Capacitor
(GCSC)
• Thyristor-Switched Series Capacitor (TSSC)
• Operating control schemes for GCSC & TSSC
• Sub Synchronous Resonance

3. GTO Thyristor-Controlled Series
Capacitor (GCSC)

4. Analogues
GCSC
• Supplied from current source
• Thyristor valve is stipulated to
close at voltage zero
• Its controlled by turn off delay
γ wrt crest of line current,
which decides the blocking
interval ζ
• Controls voltage developed by
constant current source across
fixed capacitor – Variable
reactive impedance
TCR
• Supplied from voltage source
• Thyristor valve is stipulated to
close at current zero
• Its controlled by turn on delay
α wrt crest of line current,
which decides the conduction
interval σ
• Controls current in fixed
inductor from constant voltage
– Variable reactive admitance

9. Thyristor Switched Series Capacitor
TSSC

11. Operating Control Scheme GCSC

12. Operating Control Scheme TSSC

13. Sub Synchronous Resonance (SSR)

15. Thank You