Generalized Formulation for Optimal Placement of PMUs Considering Single Unit or Single Branch Outage Nima Amin, Mahdi Banejad Faculty of Electrical & Robotic Engineering Shahrood University of Technology Shahrood, Iran ni.amin@yahoo.com, m.banejad@shahroodut.ac.ir Abstract—Phasor Measurement Units (PMUs) are being considered as the essential tools in modern power system studies. In this paper a general approach is proposed to place the PMUs optimally in a power system and minimize the total installation cost to make the entire system completely observable. In this paper, the placement of PMUs is performed with respect to the maximum measurement redundancy, considering both cases of single PMU loss or single branch outages as just one problem. The proposed approach employs Binary Integer Linear Programming (BILP) to formulate the objective function. In order to consider more practical assumptions, with and without considering of zero injections buses, this method does not utilize the existing conventional measurement units in the power network. In addition, to show the effect of unequal PMU installation in each bus, modified cost matrix is added to the problem. The proposed approach is then applied to several standard IEEE test systems (14-bus, 30-bus and 57-bus) to find the optimal placement of the PMUs. The simulation results approve the capability of the proposed method in finding the optimal place of the PMUs with minimizing the installation cost. I. INTRODUCTION Phasor Measurement Units (PMUs) are important devices in Wide Area Measurement, Protection and Control (WAMPAC) system studies. PMU is a monitoring device, which can provide synchronized measurement of voltage and current phasor in a power system. Synchronized signals are achieved from Global Positioning System (GPS) satellites [1]. PMU measurements, in compare with SCADA system, are taken at higher speed. Time stamping of each measurement; provides the precise view of the entire network interconnections. The most phasor-based applications of PMUs in industries are: visualization, monitoring, control/protection, disturbance analysis, system dynamic and state estimation [2]. In recent years, due to high cost of having PMU at each node of the network, several research activities have been performed to locate minimal set of PMUs in order to make the power system completely observable, with considering different operation conditions. Phasor measurement placement method, using graph theoretical observability analysis has been formulated in [3] and to solve the minimum number of PMUs problem, both modified bisecting search and simulated annealing has been implemented. However possible measurement loss and branch outage is not considered. In [4], the optimal PMU placement proposed with Nondominated Sorting Genetic Algorithm (NSGA). Optimal solution of objective function has been solved with graph theory and simple GA and just single branch Contingency has been considered. The proposed method requires more complexity computation and restricted by the size of the problem. Reference [1] has introduced techniques for optimal PMU placement based on incomplete observability, using simulated annealing. In accordance to incomplete observability, depth of observability was introduced in this paper. PMU placement method for power system state estimation based on the minimum number of the normalized measurement matrix has been presented in [5]. Presented method in [6] is exhaustive search- based to find minimum number and optimal placement of PMUs for complete network observability. This method gives a global optimal solution for the PMU placement, but it becomes computationally intensive for large systems. Optimal PMU placement algorithm by using nonlinear integer programming, under the existence of conventional power flow or power injection measurement has been presented in [7]. An integer quadratic programming approach to maximize the measurement redundancy was used in [8]. In [9] and [10], a similar formulation of PMU placement problem was proposed. This algorithm with and without considering conventional power flow and power measurement in system is always linear. Presented method in this paper proposes an approach to place PMUs in a power system optimally, not only to make the entire network completely observable in normal operating condition, but also it maintains observable in the case of loss of any single PMU or single branch from the network. In this 978-1-4673-5634-3/13/$31.00 ©2013 IEEE