Dynamic Harmonic Phasor Estimator Considering Frequency Deviation

The fundamental frequency of power system may deviate from the nominal value due to various reasons, such as load variation, subsynchronous resonance and fault occurrence. The maximum frequency deviation considered by the latest IEEE standard is 5 Hz. This paper proposes a dynamic harmonic synchrophasor estimator, which can accurately estimate the dynamic harmonic parameters even if the frequency deviation reaches 5 Hz. Multiple discrete frequencies are generated at a fixed frequency interval on both sides of the nominal frequency, and multiple dynamic harmonic filters are generated offline based on those frequencies. The windowed interpolation discrete Fourier transform is adopted for online monitoring of the fundamental frequency. According to the detected frequency, a harmonic filter, which is generated with the discrete frequency that is closest to the detected frequency, can be selected to analyze the dynamic harmonic synchrophasor, frequency and rate of change of frequency. The performances of the proposed estimator are verified through tests under various frequency deviation conditions, and the test results show that the proposed estimator can accurately estimate the dynamic harmonic parameters when the frequency deviation is within 5 Hz.