A PWM Based Series Compensator for Power System Performance Enhancement

Abstract

Enhancement of power system stability through a relatively new FACTS device named pulse width modulated series compensator (PWMSC) in the transmission line has been investigated in this article. The three-phase PWMSC is realized with a simple pulse width modulated (PWM) AC link converter consisting of four force-commutated switches and a three-phase diode bridge. The PWMSC is modeled as a continuously controllable series capacitive reactance in the transmission line of a power system. Nonlinear model of single machine infinite bus (SMIB) and multi-machine power system with PWMSC installed are derived and tested for various disturbances including three phase faults in the system. Proportional-integral-derivative (PID) controllers are incorporated to control the duty ratio of the switches of the PWMSC, thus controlling the equivalent injected line reactance. Effectiveness of different stabilizing input signals for the supplementary controllers has been investigated. A real-coded genetic algorithm has been employed to optimize the controller parameters. The effect of PWMSC placement in the multi-machine system in power system stabilization is also explored. From a number of simulation studies on a single machine infinite bus system and also a multi-machine power system, it was observed that the proposed PWMSC with optimally tuned controllers provide excellent damping characteristics to power system transients.

Keywords: Pulse width modulated series compensator (PWMSC), PID control, real-coded genetic algorithm (RCGA), stability of power systems

Cite this Article

Rahim AHMA, Kamal Romman M. A PWM based series compensator for power system performance enhancement. Journal of Power Electronics and Power Systems. 2016; 6(1): 12–25p.