1.National Active Distribution Network Technology Research Center, Beijing Jiaotong University, Beijing 100044, China;2.Collaborative Innovation Center of Electric Vehicles in Beijing, Beijing 100044, China;3.State Key Laboratory of Control and Operation of Renewable Energy & Storage Systems;(China Electric Power Research Institute), Beijing 100192, China
This work is supported by National Key R&D Program of China (No. 2018YFB0905200).
The grid-connected control based on inductor current on the side of converter in synchronous rotating coordinate system is widely applied in the grid-connected converter with LCL-filter. However, the axe-cross-coupling exist in the dq models of LCL filter and digital delay, which constrains the grid-connected performance and becomes worse as the switching frequency decreases. To address this issue, based on the complex vector modeling of grid-connected converter with LCL-filter, this paper analyzes the coupling characteristics of the grid-connected converter and the conventional decoupling scheme. Aiming at the shortcomings of the existing control strategies, this paper proposes an improved control strategy of the grid-connected converter with LCL-filter based on phase compensation and virtual impedance optimization. Then, the effect of virtual impedance on system coupling and system damping characteristics is analyzed in detail through the zero-pole plots. And the method for determining optimization values of three parameters are given. Finally, the simulation and experimental results show that the proposed strategy can achieve independent control of system coupling degree and damping characteristics, while effectively realize decoupling and improve system dynamic performance.
GAO Yinghan,TANG Fen,LIU Jingdou,et al.Improved Control of Grid-connected Converter with LCL Filter Based on Phase Compensation and Virtual Impedance Optimization[J].Automation of Electric Power Systems,2020,44(3):167-175.DOI:10.7500/AEPS20190330002Copy