Optimal Placement of Phasor Measurement Units Ensuring Power System Observability

Abstract

Optimal Phasor measurement unit (PMU) placement is the strategic placement of a minimum number of PMUs to ensure power system observability. Optimal PMU placement (OPP) is essential to overcome the economic burden during the deployment of PMU on every bus. A strategy integrated with the modified Simulated Annealing (SA) algorithm is proposed in this paper with the consideration of the effect of the radial buses during the OPP problem. To recognize the superior placement set from diverse solutions given by the meta-heuristic algorithm, a placement set with the least number of PMUs and a higher system observability redundancy index (SORI) is used. In addition to modified SA, the strategy of ensuring or restricting the PMU placement on the radial bus has been implemented in MATLAB. In addition to the normal case, cases for single PMU outage and zero injection bus (ZIB) have been implemented in IEEE 14-bus, 30-bus, 57-bus, and 118-bus systems. The algorithm has been also used on the existing 90-bus Integrated Nepal Power System. The result of the proposed strategy on modified SA has improved the result in terms of the optimal number of PMUs, the probability of finding an optimal number of PMUs, and SORI. For normal cases, the number of PMUs required for complete power system observability is found to be in the range of 28-33% of the total number of buses. Similarly, with the consideration of single PMU outages and ZIB, the number of PMUs required is found to be in the range of 57-70 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">%</sup> and 21-26% respectively.