Redundancy based PMU placement in state estimation

An alternative method to obtain a PMU placement with maximum measurement redundancy is proposed in this paper. By considering the number of branches adjacent to each bus, the proposed method can be formulated in a linear and compact way. The effectiveness of the proposed method is shown by comparing its results with those of the existing methods (Two-step Method and Quadratic Programming Method) under the IEEE 14-, 30-, 57- and 118-bus test systems. Different scenarios, such as normal condition, contingencies and consideration of zero-injection buses, are also discussed. Moreover, a post-processing optimization is presented to improve the redundancy distribution. After the optimization, the number of red-1 buses, i.e. buses which are made observable one time only by the measurements, is reduced. In this way the redundancy becomes more evenly distributed and the state estimation is more robust. The short execution time of the post-processing optimization and its effectiveness are verified by using various IEEE test systems.