Analysis and Design of Grid-Connected Inverter Impedance Remodeling with Fixed Stability Margin in Weak Grid
Tu Chunming1, Gao Jiayuan1, Zhao Jinbin2, Zhang Yunfei2, Guo Qi1
1. National Electric Power Conversion and Control Engineering Technology Research CenterHunan University Changsha 410082 China; 2. School of Electrical Engineering Shanghai University of Electric Power Shanghai 200090 China
Abstract：The stability control of grid-connected inverter in weak grid is studied. Based on the reconstructed impedance-based stability criterion, the current double closed-loop control of three-phase LCL grid-connected inverter is used as a model to establish a Norton equivalent series and parallel impedance mathematical model for the inverter grid-connected system. By analyzing the characteristics of inverter equivalent output impedance, the parallel equivalent output impedance of inverter is selected to be reconstructed. The impedance reconstruction control technology includes three units: grid impedance detection, phase margin compensation and amplitude correction. The reconstructed equivalent impedance model can always maintain a constant stability margin for the inverter grid-connected system when the grid impedance varies widely, meanwhile, considering the detection error of the grid impedance, the system can still maintain good steady-state and dynamic performance. Simulation and experimental measurements verify the analysis.
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2020, Vol. 35 
