Static VAR compensator

Prior to the invention of the SVC, power factor compensation was the preserve of large rotating machines such as synchronous condensers or switched capacitor banks.

In industrial applications, SVCs are typically placed near high and rapidly varying loads, such as arc furnaces, where they can smooth flicker voltage.

[5] Chopping reactive load into the circuit in this manner injects undesirable odd-order harmonics and so banks of high-power filters are usually provided to smooth the waveform.

[5] This reduces the size and number of components needed in the SVC, although the conductors must be very large to handle the high currents associated with the lower voltage.

The main advantage of SVCs over simple mechanically switched compensation schemes is their near-instantaneous response to changes in the system voltage.

Similar devices include the static synchronous compensator (STATCOM) and unified power flow controller (UPFC).

One-line diagram of a typical SVC configuration; here employing a thyristor-controlled reactor , a thyristor-switched capacitor , a harmonic filter , a mechanically switched capacitor and a mechanically switched reactor
Thyristor-controlled reactor (TCR), shown with delta connection
Thyristor-switched capacitor (TSC), shown with delta connection