A security-based observability method for optimal PMU-sensor placement in WAMS

•Proposing a security-based observability model of optimal PMU-sensor placement.•A reliable sensor-based communication system method based on PPSNs and EHSNs.•Contingency analysis of power grid to improve the WAMS security.•The impacts of ZIB and radial buses consideration in PMU-sensor placement problem. Optimal PMU placement (OPP) problem is one of the most important issues in wide area measurement systems (WAMS). Delivering the measured data to the control center is possible through communication infrastructure (CI) that is a part of the WAMS. However, to well estimate the state of the system, observability of the measurement system is necessary. In this paper, a security-based observability (SBO) method for the PMUs and related CI is proposed. A hybrid wireless sensor-based structure including energy harvesting sensor nodes (EHSNs) and plug-in powered sensor nodes (PPSNs) is utilized as the communication system. The contingency-constraint optimal PMU placement and related sensor-based CI is proposed and formulated. To increase the reliability of the CI, a reliability index for the wireless sensors is added as a constraint to the objective function which includes the total cost minimization subject to power system observability and communication constraints. The effect of zero-injection buses (ZIBs) and radial buses in the power system are also included in the model to get more practical results. A mixed-integer linear programming (MILP) is used for contingency constraint PMU placement and a binary-coded genetic algorithm (BCGA) is accordingly used for solving the examined communication optimization. The IEEE 13-bus and IEEE 37-bus test feeder systems are utilized to evaluate the effectiveness of the proposed method.