Harmonic Analysis and Suppression Strategies of Grid Current for Renewable Energy Grid Integration System

With a growing proportion of the wind,photovoltaic,fuel cells and other new energy grid integration system in the public power system,harmonic pollution has become an issues that can not be ignored.In order to resolve this problem,the reason that the grid generation produces harmonic currents were analyzed detailedly,and three-phase half-cycle of PWM modulation strategy was put forward.This strategy needn't set the dead time and can overcome the harmonic current whitch produced by the dead time effect of traditional three-phase PWM switching signal.At the same time,virtual resistor was adopted in inverter-side filter inductor to suppress the resonance of T filter and reduce harmonic current.These methods are simple and easy to implement.The results of simulations show the validity of the proposed strategy for harmonic suppression.