Improvement of power system dynamic performance with the magnitude and phase angle control of static phase shifter

Control strategies of static phase shifter (SPS) have been widely investigated to improve the stability of power systems. But the emphasis has been limited to the control of the phase angle of the SPS. However, much improvement in the system dynamic performance may be possible with the control of both the magnitude and the phase angle of the phase shifter. Installing such a phase shifter is equivalent to incorporating a general voltage source in series with transmission line. This will modify the system equations and therefore the power flows. Hence, the steady state and the dynamic performance of power system would depend on these modified equations. In this paper, we have derived the equations for a system incorporating SPS. We have also developed a control strategy considering control of both the magnitude and the phase angle of SPS. This may be one form of unified power flow controller (UPFC). Simulation results are presented to demonstrate the effectiveness of the developed control strategy. (C) 2000 Elsevier Science S.A. All rights reserved.