Damping Performance Enhancement of a Power System by STATCOM and its Frequency Stability Consideration

Abstract

This thesis investigates the damping performance of power systems through eigenvalue analysis and the impact of cyber-attack on power systems in frequency disturbing aspects during sudden changes of load. It also proposes a solution method to make the system stable. The analysis is firstly carried out on the Western System Coordinating Council (WSCC) 9-bus test system to find the impact of location of Flexible AC Transmission System (FACTS) devices on the static voltage stability. The maximum loadability of the load buses is determined using continuation power flow method with static var compensator (SVC) and static synchronous compensator (STATCOM). The result shows that the reactive power support from the FACTS devices depends on the proper placement of the FACTS devices in the network. The analysis is then conducted on an IEEE 14-bus test system. The maximum loading limits of the load buses are determined using continuation power flow method and a static synchronous compensator (STATCOM) is installed as an objective to increase the systems loadability. Then, the dominant modes and associated states that affect the damping of the system are identified and an oscillation damping controller is designed. The result shows that the proposed damping controller equipped with STATCOM can improve the damping performance of the system significantly. In order to analyze the impact of cyber attack on power systems, the stable limit of speed regulation for load frequency control (LFC) and integral controller gain for automatic generation control (AGC) is derived from their characteristic equations. Depending upon the nature of cyber-attack (positive biased or negative biased attack), simulations are performed to show the frequency deviations and oscillations of the power system. Finally, a feedback LFC block with a three input switch is proposed to remove these oscillations.