The document discusses Thyristor Controlled Series Compensation (TCSC), a FACTS device that uses thyristors to control the capacitive reactance of transmission lines. TCSC can enhance power flow, limit fault current, improve stability and transients. It introduces benefits like mitigating subsynchronous resonance risks, damping power oscillations, and improving post-contingency stability. TCSC operates in modes like blocking, bypass, capacitive boost and inductive boost to accurately regulate power flow and damp oscillations while increasing transmission capacity and stability.

1. FACTS
EEE-B
Batch-5

2. INTRODUCTION
 The TCSC concept is that capacitor is inserted directly
in series with the transmission line and the thyristor
controlled inductor is mounted directly in parallel
with the capacitor.
 Thus no interfacing equipment like high voltage
transformer is required.
 So TCSC is more economic than some other
challenging FACTS technologies.

3. TCSC
Thyristor controlled series capacitor is a series FACTS
device. TCSC is a capacitive reactance compensator.
It is a more effective and provides suitable solutions due to
flexible control of thyristor. TCSC is connected in series
with the transmission line conductors.

4. Basic scheme of TCSC

5. TCSC
 TCSC plays vital roles in the operation and control of power
systems such as
1. Enhancing power flow
2. limiting fault current
3. Enhancing transient
4. Dynamic stability

6. Uses of TCSC
 Increase power transmission capability
 Improve system stability
 Reduce system losses
 Improve voltage profile of the lines

7. TCSC
Thyristor-controlled series compensation (TCSC)
introduces a number of important new benefits in the
application of series capacitors
• Mitigation of subsynchronous resonance risks
• Damping of active power oscillations
• Post-contingency stability improvement
• Dynamic power flow control

8. Damping of power oscillations
 Oscillations of active power in power transmission
systems may arise in corridors between generating
areas as a result of poor damping of the
interconnection, particularly during heavy power
transfer. Such oscillations can be excited by a number
of reasons such as line faults or a sudden change of
generator output.

9. Damping of power oscillations
Uncontrolled
TCSC

10. Operating modes of TCSC
 Blocking mode
 Bypass mode
 Capacitive boost mode(Capacitive vernier mode)
 Inductive boost mode(Inductive vernier mode)

11. Modes of TCSC

12. Cont…
 In case of blocked operating mode, the thyristor valve is not triggered
and the thyristor are kept in non- conducting state.
 In case of bypass mode, as the thyristors are fully conducting, most of
the line current flows through thyristors and hence TCSC has small net
inductive reactance.
 In Vernier control, thyristors are conducted in such a manner that a
controlled amount of inductive current can circulate through the
capacitor, thereby increasing effective capacitive/inductive reactance of
the module.

13. Advantages of TCSC
 Increase power transmission capability
 Improve system stability
 Reduce system losses
 Improve voltage profile of the lines
 Optimize power flow between parallel lines
 Damping of the power swings from local and inter area
oscillations

14. Application of TCSC
 Accurately regulating the power flow on a
transmission line
 Damping inter area power oscillations,
 Mitigating subsynchronous resonance (SSR)
 Improving transient stability