Mechanism Analysis of the Harmonic Emission in Photovoltaic System

With the increasing integration of renewable energy sources represented by photovoltaic, harmonic issues can no longer be neglected. To better describe the harmonic emission properties of photovoltaic generation system, an equivalent model that can accurately calculate the output harmonic current of photovoltaic generation system is proposed by analyzing the mechanism of harmonic generation of photovoltaic power. Aiming at the problem of harmonics generated by photovoltaic modules and relevant control strategies, the harmonic current expression is constructed by analyzing the mechanism of harmonic generation. As for the harmonics generated by the inverter, the expression of inverter harmonic transfer function considering the impact of external harmonic disturbance and dead-time effect is established. The equivalent expression of photovoltaic output harmonic current is derived so as to establish a photovoltaic power generation harmonic equivalent model. Finally, the validity of the derived model is verified by the emulation.