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In Electrical Engineering, a static VAR compensator (SVC) is a set of electrical devices for providing fast-acting reactive power on high-voltage electricity transmission networks. [ 1 ] [ 2 ] SVCs are part of the flexible AC transmission system [ 3 ] [ 4 ] device family, regulating voltage, power factor, harmonics and stabilizing the system.
The STATCOM also provides better reactive power support at low AC voltages than an SVC, since the reactive power from a STATCOM decreases linearly with the AC voltage (the current can be maintained at the rated value even down to low AC voltage), as opposed to power being a function of a square of voltage for SVC. [38]
The task of additional reactive power compensation (also known as voltage compensation) is assigned to compensating devices: [7] passive (either permanently connected or switched) sinks of reactive power (e.g., shunt reactors that are similar to transformers in construction, with a single winding and iron core [9]).
Heavily loaded lines consumed reactive power due to the line's inductance, and as transmission voltage increased throughout the 20th century, the higher voltage supplied capacitive reactive power. As operating a transmission line only at it surge impedance loading (SIL) was not feasible, [ 2 ] other means to manage the reactive power was needed.
The reactive power produced by a capacitor bank is in direct proportion to the square of its terminal voltage, and if the system voltage decreases, the capacitors produce less reactive power, when it is most needed, [2] while if the system voltage increases the capacitors produce more reactive power, which exacerbates the problem. In contrast ...
A unified power flow controller (UPFC) is an electrical device for providing fast-acting reactive power compensation on high-voltage electricity transmission networks. It uses a pair of three-phase controllable bridges to produce current that is injected into a transmission line using a series transformer. [ 1 ]
It consists of a power capacitor connected in series with a bidirectional thyristor valve and, usually, a current limiting reactor . The thyristor switched capacitor is an important component of a Static VAR Compensator (SVC), [1] [2] where it is often used in conjunction with a thyristor controlled reactor (TCR).
V svc is the rms value of the line-to-line busbar voltage to which the SVC is connected L tcr is the total TCR inductance per phase The current lags 90° behind the voltage in accordance with classical AC circuit theory. As α increases above 90°, up to a maximum of 180°, the current decreases and becomes discontinuous and non-sinusoidal.