Cost-Effective Upgrade of PMU Networks for Fault-Tolerant Sensing

This paper considers robust allocation of additional phasor measurement units (PMUs) into a PMU network in order to meet a data availability profile in the face of random communication interruptions and transmission line faults. Synchrophasor availability (SA) at a bus is the fraction of time the time-synchronized current/voltage phasors are correctly present for real-time usage. An algorithm that achieves the above objectives is developed. The algorithm switches between a placement step solved via integer programming and an SA evaluation step that uses a bus-centric stochastic model to efficiently determine the need for another placement step with a tightened constraint. The algorithm is shown to subsume the phasor observability and is equally applicable PMU network upgrade and creation. Scalability and computational efficiency of the algorithm are analyzed. The results of tests of the algorithm applied to the IEEE 118-bus system are reported, which are performed under a variety of availability specifications and random event arrival rates associated with communication interruptions, equipment faults, and their removals. Superior accuracy and fault tolerance in state estimation are achieved by PMU networks meeting more stringent SA.