Design and analysis of pole-placement controller for dynamic stability improvement of VSC-HVDC based power system

Immense improvement in power system stability can be achieved by the inclusion of Voltage Source Converter (VSC) based Back to Back (BtB) HVDC in the system. In this paper, a single machine infinite bus (SMIB) power system incorporating VSC based BtB HVDC is considered for dynamic stability assessment and linearised model of the system is presented. The system dynamic response is analyzed under small disturbance. A supplementary controller is designed based on pole placement technique which enhances damping of system low frequency oscillation. Pole placement is a control method assigned to arbitrary close loop poles by state or output feedback. The system step response with and without controller is determined which demonstrates the effectiveness of the pole placement controller. Moreover, the system step response is evaluated for all the four control input signals of HVDC. The desired values of gain have been calculated by Ackermann´s formula. Simulation results carried by MATLAB show that the pole placement controller, provides significant improvement in the system dynamic performance in terms of peak overshoot and settling time.