Robust PMU Placement in Branch Switching Power Networks for Minimum Variance State Estimation

Abstract

Phasor Measurement Units (PMUs) are measurement devices that measure voltage phasor data of a bus and current phasors of adjacent branches in a power network. With information on the power network impedance, a finite number of PMUs are used to estimate the voltage on all buses, also known as the state of the power network. Traditionally, the problem of Optimal PMU Placement (OPP) focuses on having complete observability of the network state by strategically placing a minimum number of PMUs. A change in network topology caused, for example, by network switches, changes the solution to the OPP problem. Since it is not feasible to change the locations of PMUs after every change in topology, the contribution of this paper is a PMU placement optimization algorithm which minimizes the variance on the estimated voltages and is also robust to the changes to the network topology. The optimization guarantees robustness to the change in network topology. Since it considers each change in the switch position as a different network topology, the optimization criterion is a multi-objective optimization function for different network topologies caused by changing the switch positions of the same network. The proposed robust optimal placement algorithm can be used for single current-channel PMUs and multi-current channel PMUs. The algorithm is tested on IEEE 14 bus network. The results show that the robust optimal placement can significantly reduce the effects of PMU measurement noise on the estimated states on average for different switch positions.