Thyrsitor Controlled Reactors


TCRs are extensively used in dynamic VAR compensation applications such as Static Var Compensation (SVC).
A thyristor-controlled reactor (TCR) is connected in series with a bidirectional thyristor valve. The TCR reactor generates inductive reactive power of SVC. TCR's are essentially shunt reactors, but the current is continuously regulated by the thyristor valves. The three phase reactors are delta connected and each phase is split into two coils and the thyristors are connected between the coils. Changing the trigger angle of a thyristor alter its admittance which will vary the fundamental current thereby varying the reactive power absorbed by the reactor.

The capacitor provides fixed compensation for the reactive power in SVC, while TCR can absorb continuously controlled reactive power with a lagging power factor. The SVC thus expands the dynamic compensation range with both lagging and leasing power factors.

Static VAr compensation system using thyristor controlled reactors can take care of PF correction, voltage variation, flicker compensation, harmonic suppression, containing oscillations etc all under one roof. The reactors current
can be controlled in continuous manner from zero, if the
switch is turned off, to its maximum value, when the
reactor is directly connected to the source. Quality Power
manufactures highly robust TCR's with Q factor >175 up to
1OO MVAr rating.

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