Online Measurement Method of Dynamic Harmonic Phasor for Frequency Deviation and Frequency Dynamic Changing Conditions

New energy power generations are integrated into power grids using power electronic devices, which intensifies the harmonic pollution of power grids. High-precision online measurement of dynamic harmonic phasor is the key prerequisite for harmonic monitoring, localization and suppression. The Taylor Fourier transform method can track time-varying harmonic phasor with high accuracy, but the heavy computational burden and memory requirement in the frequency deviation and frequency dynamic changing conditions make it difficult to be applied to embedded measurement units with limited resources, which is the main obstacle to engineering applications. In regard to this problem, the identification error is theoretically analyzed when the harmonic frequency deviates from the central frequency of passband of Taylor Fourier transform filter, and the nonlinear relationship between the measured value of frequency deviation and the true value is elucidated. Then a fast measurement method of dynamic harmonic phasor based on Newton iterative correction of frequency deviation is proposed, which solves the problem of high-precision online measurement of dynamic harmonic phasor based on Taylor Fourier transform in frequency deviation and dynamic change conditions. The simulation results show that the proposed method can achieve high- precision measurement of dynamic harmonic phasor in several conditions such as large-range frequency deviation, frequency ramp change, frequency oscillation change, magnitude ramp change, magnitude oscillation change, etc. The proposed method requires small memory space and low computational burden. Finally, the measurement method of dynamic harmonic phasor is implemented in the embedded measurement unit, and the measurement accuracy and execution speed are further verified by measuring the playback signal of the reconstructed electromagnetic waveform distorted by harmonics based on an actual dynamic condition of the power grid in real time, demonstrating the application potential of the proposed method in high-precision online measurement of dynamic harmonic phasor in the new energy power grids. ©2024 Chin.Soc.for Elec.Eng. 8759.