A Real-Time Harmonic Extraction Approach for Distorted Grid

Harmonic interference is a major hazard in the current power system that affects quality. How to extract harmonics quickly and accurately premise ensure sustainable operation of system, which particularly important field new energy generation. In this paper, harmonic extraction method based on time-varying observer proposed. Firstly, frequency estimation algorithm used estimate grid frequency, can real time. Then, applying zero-crossing detection convert into phase variable. Finally, using variable integral signal as input, modeled each order component. The proposed evaluated FGPA test platform, shows components converge within 80 ms even presence distortions. verification case, relative errors 1st, 5th, 7th 11th are 0.005%, −0.003%, 0.251% 0.620%, respectively, sufficiently small.