APPLICATIONS OF STATIC PHASE SHIFTERS IN POWER-SYSTEMS

A companion paper [1] describes different types of semiconductor-controlled (static) phase shifters feasible for power system applications. This paper examines various functions that can be assigned to a Static Phase Shifter (SPS) to enhance the performance of a power system during steady-state conditions, small-signal dynamics, and large-signal dynamics. The investigations are conducted on four test systems which exhibit typical power system operational problems, e.g. torsional oscillations, inter-area oscillations, transient instability, transient mechanical torques and loop-flow phenomenon. An ac-dc power flow program, an eigenvalue analysis program, an ac-dc transient stability program, and the EMTP are used as the study tools. The investigations show that depending upon the type and the location of an SPS, it may be utilized for mitigation of small-signal oscillations and/or enhancement of transient stability, in addition to steady-state power flow regulation. The studies also reveal that most dynamic characteristics of an SPS can be achieved by augmenting an existing conventional (mechanical) phase-angle regulator with a relatively small size static converter.