Joint improvement of system loadability and stability through a multi-stage planning of a UPFC with a PMU-based supplementary damping control

One of the most important issues for power system security is to effectively damp the power system oscillations in order to enhance transient stability and improve dynamic performance. Traditionally, oscillations have been damped by Power System Stabilizer (PSS). In recent years, FACTS devices combined with a supplementary controller-known as a Power Oscillation Damper (POD)-have been also used to damp low-frequency oscillations in power systems. In this paper, a multi-step plan is developed to implement a Wide-Area Power Oscillation Damping (WA-POD) controller of a UPFC in 14-bus test system. The first step of this plan is to find the optimal location for the UPFC to maximize power system loadability; the second step is to estimate the dynamic states of the synchronous generators; and the third step is to implement the WA-POD controller using the states estimated in step two. The estimated rotor angles are used to provide the input signal of the WA-POD controller while the estimated rotor speed deviations will be used for an off-line parameter tuning of both PSS and WA-POD using the genetic algorithm. Different types of faults are applied to the network to compare the performance of the traditional PSS and the WA-POD controller in the 14-bus test system. Simulation results show the effectiveness of the implemented WA-POD controller in damping low-frequency oscillations and improving the dynamic performance of the system.