Revisit Optimal PMU Placement With Full Zero-Injection Cluster and Redundancy Sharing

Due to the expensive deployment cost, finding the minimum Phasor Measurement Unit (PMU) to meet the observability requirement has been attractive since the invention of PMU. Many research efforts have been put to zero-injection nodes (ZINs) in optimal PMU placement (OPP). We revisit OPP and define a full Zero-injection cluster (ZIC) as a set of nodes adjacent to ZINs together with at least one ZIN, establishing a novel ZIC-based OPP model. Compared with the existing literature, the full ZIC can cover more nodes, resulting in a better solution. To find all full ZIC, we propose a dynamic adjacency matrix based full-ZIC search algorithm, which has quadratic-time complexity. It could have wide applications, and can be applied in many OPP works. Besides, redundant PMUs within the full ZIC can be shared within large areas post contingency. A concept of redundancy sharing is proposed for post-contingency ZIC model, whose observability can be guaranteed with proposed redundancy-sharing conditions. Comprehensive case studies are conducted using the proposed approaches. The simulation results for both IEEE cases and a real-world system show the proposed method can further reduce PMU deployment number.