Research on Harmonic Characteristics of Renewable Energy Grid Connection

With the high proportion of renewable energy integration, harmonic issues in the power grid are becoming increasingly prominent. This paper establishes models for wind power generation, photovoltaic power generation, and thermal power generation. It analyzes the harmonic characteristics of renewable energy grid-connected inverters and proposes a Norton equivalent model for inverters based on SPWM (Sinusoidal Pulse Width Modulation) modulation. Through simulation studies, the paper investigates the harmonic variation patterns of inverter output voltage and current under different renewable energy output ratios. The results show that the increase in the proportion of renewable energy significantly improves the harmonic distortion rate of voltage and current, especially the 5th and 7th harmonics, and high-order harmonics are prone to derive low order harmonics.