Estimation of Electric Power Quantities for Nonsinusoidal Conditions Based on Operating Point Fluctuations

ABSTRACT

As the penetration of power electronic converters and renewable generation increases, voltage and current waveforms in power systems are increasingly distorted and nonstationary. Accurate estimation and fast tracking of electric power quantities are essential for energy metering and billing, online monitoring, and safe operation of power systems. However, most existing estimation methods assume that the waveform within an observation window is stationary and periodic, which often leads to a slow dynamic response under nonstationary conditions and introduces estimation errors when the fundamental frequency deviates from its nominal value. To address these challenges, this paper introduces a framework termed operating point fluctuations (OPF). In the OPF framework, a nonstationary waveform is reinterpreted by treating the time‐varying fundamental component as a dynamic operating point and describing all distortions as fluctuations around it. Based on this framework, a set of single‐phase and three‐phase power quantity expressions is derived. Furthermore, an estimation method is proposed. Comprehensive simulation studies demonstrate that the proposed method achieves high accuracy under stationary conditions, fast dynamic tracking under nonstationary conditions, low computational burden, and robustness to noise and fundamental frequency deviation. Validation using field measurement data further confirms these results and demonstrates its suitability for practical applications.