Least-Cost Joint Placement of PMUs and Flow Measurements for Ensuring Topological Observability under N-2 Contingencies While Improving State Estimation Accuracy

This paper discusses an optimal joint placement problem of phasor measurement units (PMUs) and flow measurement devices for ensuring topological observability of power systems under N-2 transmission contingencies. Previous relevant studies focus on topological observability with the least-cost deployment of PMUs and flow measurement devices. In comparison, besides minimizing the total investment cost of PMUs and flow measurements, the proposed optimal location-based joint placement model also optimizes their locations for avoiding PMUs on radial nodes and encouraging flow measurements incident to nodes that are adjacent to PMU installed buses. The proposed model can be equivalently formulated as a mixed-integer linear programming (MILP) problem and solved via a decomposition based algorithm. Effectiveness of the proposed model is verified via a 14-bus IEEE power system. Numerical results show that, compared to traditional optimal joint placement models, optimal locations obtained by the proposed approach lead to noticeable improvements in state estimation accuracy when time skew errors are considered.