Critical analysis of PMU testing procedures for step response evaluation

The Phasor Measurement Units (PMUs) are becoming an important element for the measurement systems of the electrical grid. To assure the high penetration of these measurement devices, the interoperability of the PMUs from different vendors must be ensured. The IEEE Standard C37.118.1-2011, with its amendments of 2014, defines two accuracy classes, P and M, and provides the steady state and the dynamic tests to be passed to achieve compliance. This paper focuses on the dynamic compliance in presence of step changes in phase and magnitude. In particular, the approach proposed by the standard to evaluate the performance of a PMU when it is exposed to a step change signal input is analyzed and compared with a complete sample by sample approach in a simulation environment. The measurement results, in terms of response time, delay time and undershoots/overshoots and their accuracies, for different reporting rate, are discussed.