Redundant Observability PMU Placement in the Presence of Flow Measurements Considering Contingencies

Abstract

Phasor measurement units (PMUs) have made it possible to observe and control wide-area power systems. In this paper, a new redundant observability method as a mixed-integer linear programming (MILP) is presented for optimal PMU placement. Redundant observation of buses enhances measurement reliability. The proposed method improves observability redundancy by a new objective function while using the same number of PMUs as the existing methods. Because of using MILP, the global optimal integer solution is achieved with a zero optimality gap. In addition, a systematic novel approach is proposed to incorporate already installed branch flow measurements in the PMU placement problem leading to a reduced number of PMUs required for system observability. This approach is able to handle both single and multiple flow measurements incident to a bus. PMU placement in case of PMU failure or branch outage is also studied. The proposed method along with an existing method is tested on four IEEE and Polish 3375-bus test systems. Obtained results, discussed in detail, show the efficiency of the proposed method in both speed and accuracy.