A thyristor-switched capacitor (TSC) is a type of equipment used for compensating in electrical power systems. It consists of a power connected in series with a bidirectional valve and, usually, a (). The thyristor switched capacitor is an important component of a (SVC), where it is often used in conjunction with a (TCR). Static VAR compensators are a member of the.
It consists of a power capacitor connected in series with a bidirectional thyristor valve and, usually, a current limiting reactor (inductor). The thyristor switched capacitor is an important component of a Static VAR Compensator (SVC), where it is often used in conjunction with a thyristor controlled reactor (TCR).
What happens if a thyristor valve is switched off?
In the off-state voltage, the TSC should be off and there is no current flow in the thyristor-switched capacitor. The voltage is supported by the thyristor valve. If the TSC is switched off for a long time, then the capacitor will fully discharge and the thyristor valve will experience the AC voltage of an SVC bus bar.
Why does a thyristor valve have a lower impedance than a capacitor?
The controlled reactor has a significantly lower impedance than the capacitor so that when the thyristor valve is fully conducting, the overall impedance of the capacitor section becomes inductive; the current through the reactor is greater than the line current and the capacitor current is smaller.
How thyristor switched capacitor is used in EHV lines?
The thyristor switched capacitor is used in EHV lines for providing leading VARs during heavy loads. The current through the capacitor can be varied by controlling the firing angles of back to back thyristor connected in series with the capacitor.
Are thyristor-controlled series capacitors sinusoidal?
Thyristor-controlled series capacitors (TCSC). Fig. 28.17 presents the current and voltage waveforms in the TCSC, showing that although there is a large amount of harmonics in the capacitor and reactor currents, capacitor voltage is almost sinusoidal.
When the current flows through the reactor is controlled by the firing angle of the thyristor. During every half cycle, the thyristor produces the triggering pulse through the controlled circuit. The TSC stands for the Thyristor switch capacitor. It is an equipment used for compensating the reactive power in the electrical power system.