Editing Static VAR compensator (section)

===Principle===
Typically, an SVC comprises one or more banks of fixed or switched shunt [[capacitor]]s or [[inductor|reactors]], of which at least one bank is switched by thyristors. Elements which may be used to make an SVC typically include:
*[[Thyristor-controlled reactor]] (TCR), where the reactor may be air- or iron-cored
*[[Thyristor-switched capacitor]] (TSC)
*[[LC_circuit#Series_circuit|Harmonic filter(s)]]
*Mechanically switched capacitors or reactors (switched by a [[circuit breaker]])

[[File:Static VAR Compensator 2a.png|center|thumb|560px|[[One-line diagram]] of a typical SVC configuration; here employing a [[thyristor-controlled reactor]], a [[thyristor-switched capacitor]], a [[LC_circuit#Series_circuit|harmonic filter]], a mechanically switched capacitor and a mechanically switched reactor]]

By means of phase angle modulation switched by the thyristors, the reactor may be variably switched into the circuit and so provide a continuously variable [[AC power|VAR]] injection (or absorption) to the electrical network.<ref name="Deb" /> In this configuration, coarse [[Potential difference|voltage]] control is provided by the capacitors; the thyristor-controlled reactor is to provide smooth control. Smoother control and more flexibility can be provided with thyristor-controlled capacitor switching.<ref name="Padiyar">{{cite book|last=Padiyar|first=K. R.|title=Analysis of Subsynchronous Resonance in Power Systems|publisher=Springer|year=1998|pages=169&ndash;177 |isbn=978-0-7923-8319-2|url=https://books.google.com/books?id=QMSELoMjsg0C&pg=PA169}}</ref>

[[File:Thyristor Controlled Reactor circuit.png|thumb|Thyristor-controlled reactor (TCR), shown with delta connection]]

[[File:Thyristor Switched Capacitor circuit.png|thumb|Thyristor-switched capacitor (TSC), shown with delta connection]]

The thyristors are electronically controlled. Thyristors, like all semiconductors, generate  heat and [[deionized water]] is commonly used to cool them.<ref name="Ryan"/> Chopping reactive load into the circuit in this manner injects undesirable odd-order [[harmonic]]s and so banks of high-power [[Electronic filter|filters]] are usually provided to smooth the waveform. Since the filters themselves are capacitive, they also export MVARs to the power system.

More complex arrangements are practical where precise voltage regulation is required. Voltage regulation is provided by means of a [[Feedback|closed-loop]] controller.<ref name="Padiyar" /> Remote [[SCADA|supervisory control]] and manual adjustment of the voltage set-point are also common.