Transient Minimization Within Static Var Compensated Distribution Systems

Abstract

VAR support should be supplied as close to the load as possible to minimize transmission losses. For voltage control and for improvement of total power factor in a distribution system the circuit- breaker switched capacitor banks can be used. The problems with this solution are the voltage steps caused by the large sizes of the capacitor banks as well as the transients caused on insertion. Thyristor-switched capacitors (TSC) as applied to distribution systems are the main focus of this paper. The advantage of thyristor switching is that finer and frequent switching can be used without wear on the switching element. In addition, the thyristor can give "point on wave" switching with the potential of very low transients on insertion or removal. The interaction of inrush-limiting inductors, the supply transformer and also the effect of initial conditions of capacitor banks to minimize transients have been studied. In this paper transient minimization is examined by simulation and confirmed by experimental studies.