Design of LCL-filter considering the control impact for grid-connected inverter with one current feedback only

An LCL-filter draws much attention in grid-connected applications, but the design faces challenges. The LCL and controller parameters are interdependent and inter-restricted as the grid current quality and control stability rely on the parameters of them both. In the past, researchers found that extra sensors or complex algorithms were required for the stability when the LCL parameters were designed independently. Consequently, the system cost and complexity were increased. Indeed, the LCL-filter with the delay-dependent single-loop current control can be stable if the LCL parameters are properly selected. Based on this thought, this study proposes to design the LCL parameters by considering their impact on the stability and dynamic of the inverter. Extra sensors or complex algorithms are no longer required. Based on establishing the model of the single-loop inverter-side current controlled inverter, the criteria of LCL design are obtained in order to improve the stability and the rejections of low-order and switching current harmonics. Based on those design criteria, a step-by-step procedure is proposed. Selected results have been provided to demonstrate the effectiveness of the proposed design.