Research on the Invasive Measurement Method of System Harmonic Impedance Based on Capacitor Switching

The harmonic problem of the power grid is getting more and more serious as a significant number of power electronic devices and associated control technologies are used to new energy generation and load control. Accurate measurement of the harmonic impedance of the power system is important for the classification of harmonic responsibility, harmonic control, research of harmonic penetration characteristics and the design and operation of the power grid itself. To enhance the conventional capacitor switching method, wave trap and windowed Fourier transform algorithm are introduced. Wavelet transform theory is used to reduce noise, and a better denoising effect is obtained while taking into account the impact of background harmonic and noise of the actual power grid. The simulation experiment findings demonstrate that even when dealing with background harmonic and noise influences, the enhanced approach is still capable of achieving excellent measurement accuracy.