A High-Accuracy Phasor Estimation Algorithm for PMU Calibration and Its Hardware Implementation

Abstract

Phasor measurement units (PMUs) are one of the most effective devices for measuring power system dynamics, and it is critically important that they have good performance. This paper proposes a high-accuracy synchrophasor estimation algorithm and builds a PMU calibrator to offer reference values for PMU test and calibration in the laboratory. Based on a general signal-fitting model, a nonlinear-fitting-based phasor and frequency estimation algorithm using an iterative solution are proposed. A rate-of-change-of-frequency (ROCOF) estimation method using the filter spectrum characteristic of a least-squares method is proposed to improve ROCOF measurement accuracy under dynamic conditions. For PMU laboratory tests, an interference suppression method and a post-processing method for step tests are presented. Then, the selected hardware for the PMU calibrator is tested, and its influence on phasor measurement is analyzed. Simulations and experiments verify that the accuracy of the calibrator is at least 30 times better than the requirements in PMU compliance standards of both IEEE and China, indicating that it can be used for PMU testing and calibration. In addition, the calibrator is also verified that it can offer references with high accuracy under combined tests, since the proposed algorithm is based on one general signal-fitting model.