《《Weighted Average Current Control in a Three-Phase Grid Inverter With an LCL Filter 》.pdf

IEEE TRANSACTIONS ON POWER ELECTRONICS, VOL. 28, NO. 6, JUNE 2013 2785 Weighted Average Current Control in a Three-Phase Grid Inverter With an LCL Filter Ning He, Dehong Xu, Senior Member, IEEE, Ye Zhu, Student Member, IEEE, Jun Zhang, Guoqiao Shen, Member, IEEE, Yangfan Zhang, Jie Ma, and Changjin Liu Abstract—A novel control method, named weighted average cur- easily leads to resonance due to lower damping characteristics rent control (WACC), is proposed for damping control of a three- of the high-order system. phase grid inverter with an LCL filter. In this method, the sum Current feedback proportional-integral (PI) control with grid of partial inverter current and partial grid current is used as the feedback of the current control loop. By using WACC, three-phase voltage feed-forward is commonly used in stationary reference current control of the grid inverter can be well decoupled un- frame for current-controlled inverters. But it has two main draw- der synchronous rotating frame. Furthermore, the system transfer backs: failure of tracking a sinusoidal reference without steady- function is reduced from the third-order system to the first-order state error and poor damping control ability to the inverter with system. Consequently, the control loop gain and bandwidth can an LCL filter. Grid voltage feed-forward is often used to get be increased, which improve the rejection capability to the back- ground grid voltage harmonics. The performance of the proposed a good dynamic response, but this leads to the increase of the control is also analyzed in case of filter inductance variation. Fi- grid v