Dynamics of thyristor switched capacitors

What is a thyristor switched capacitor?

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 is a thyristor-switched series capacitor (tssc)?

Thyristor-switched series capacitor (TSSC). Thyristor-controlled series capacitor (TCSC). Switching converter series FACTS controllers use switching converters to provide variable series voltage sources. They include: Static synchronous series compensator (SSSC).

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.

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 can a series capacitor be continuously controlled?

In this compensator, the equivalent value of the series connected reactor can be continuously controlled by adjusting the firing angle of the thyristors. As a consequence, this device presents a continuously controllable series capacitor. Various practical systems based on this concept are under operation around the world [13–15].

Can a thyristor switch be used to bypass a capacitor?

It is impossible to obtain rapid or frequent bypassing and re-insertion of capacitor sections using conventional mechanically operated switchgear, but faster switching can be achieved using thyristor switches for one or more sections, Figure 41.37 (a).