Data-Availability-Constrained Placement of PMUs and Communication Links in a Power System

This paper presents a solution to placing a minimum number of phasor measurement units (PMUs) and communication links in a power system so that the steady-state availability of synchrophasor data at each bus meets a prescribed level. For this purpose, a Markov model suitable for the evaluation of synchrophasor availability is built. The model contains a set of binary decision variables representing actions or inactions to maintain PMUs or to utilize communication links. The decision variables are solved to minimize an expected cost for maintaining a PMU network and utilizing data links for synchrophasor inference, subject to a set of synchrophasor availability requirements at the buses. The new aspects of development in this paper concern first the selection of decision variables so that their solutions immediately imply whether a PMU should be placed at a bus and whether a communication link should be established between two buses and, second, the solution to PMU network placement in a large-scale electric network. In addition, permanent and random intermittent PMU outages are modeled. A five-bus power system is used to demonstrate the problem formulation, and placement results are presented. A method to treat a large power system as interconnected smaller power systems with common boundary buses is proposed to address the curse of dimensionality encountered. Each smaller power system formulates an independent optimal placement problem with constraints on matching boundary placement. The steps involved are illustrated through a 14-bus system. The complexity and optimality of a divided problem are compared to that of the original problem.