Dynamic quadrature booster as an aid to system stability

Quadrature boosters (QB) have been widely used to control the power flow distribution between parallel transmission lines. The advent of very fast thyristor/vacuum switch tap changers makes the dynamic quadrature booster a powerful FACTS device for the improvement of the transient and dynamic stability of power systems. The basic concepts of the dynamic QB operation, the modelling aspects of multimachine power systems in which dynamic QB are situated, the ideal control strategy and practical considerations are presented. Simulations show that in a small simple power system, the QB can substantially suppress disturbances before swings in load angle have become large. In a large interconnected system, the action is less successful