Thyristor controlled series compensation technology
From a principal technology point of view, the TCSC resembles the conventional series capacitor. The power equipment is located on an isolated steel platform, including the thyristor valve used to control the inductor in parallel with the capacitor bank. The inductor is placed on support insulators outside the platform. Control and protection systems are located on ground potential, together with other auxiliary systems.
Thyristor controlled series compensation principle
There are two main principles supporting TCSC technology.
- First, the TCSC provides electromechanical damping between large electrical systems by modulating the reactance of one or more specific interconnecting power lines, in other words, the TCSC will provide a variable capacitive reactance.
- Second, the TCSC will change its apparent impedance (as seen by the line current) for subsynchronous frequencies in such a way that a potential subsynchronous resonance is avoided.
The TCSC achieves both objectives by using control algorithms that work concurrently. The controls will function on the thyristor circuit (this in parallel to the main capacitor bank) such that controlled charges are added to the main capacitor, making it a variable capacitor at fundamental frequency but a "virtual inductor" at subsynchronous frequencies.