Power electronics in electric utilities: static VAR compensators

The author deals with dynamic VAR compensation of electric power systems, applying power electronics for reactive power generation and control. After an overview of the emergence and status of modern, solid-state VAR compensators in utility and industrial applications, it is shown how dynamic VAR compensation increased transmittable power by providing voltage support, transient stability improvement, and power oscillation damping in electric power transmission systems. Methods of reactive power generation and control using thyristor-controlled reactors, with fixed and thyristor-switched capacitors or modern gate-turn-off (GTO) power converters that can function without AC capacitors or reactors, are described. A summary is included of the control structure and operation to provide the desired characteristics and performance in power systems applications