Method of resonance instability analysis of multiple grid-connected inverters in weak grid
Zhang Zhanjun1, Li Jianwen2, Dong Yao1, Wang Jianfeng1, Yang Huaijian1
1. State Grid Haixi Power Supply Company, Golmud, Qinghai 817000; 2. State Key Laboratory of Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Baoding, Hebei 071003
Abstract：Aiming at the resonance instability problem of multiple grid-connected inverters in weak grid, in this paper, the modal analysis method based on the node admittance matrix of the grid-connected system is applied to study the multi-inverter grid-connected resonance instability. First, the equivalent impedance model of a multi-inverter grid-connected system is established. Then, the application principles of impedance analysis method, frequency domain analysis method and modal analysis method in the study of multi-inverter grid-connected resonance instability are expatiated respectively, and the application characteristics of the three methods are compared. And the modal analysis method is applied under multiple inverters with different control types. The results show that the resonance instability frequencies of grid-connected system obtained by the above three methods are the same, and the modal analysis method is the most convenient method, which could get more available and comprehensive resonance information. Finally, the validity and correctness of three analysis methods are verified by Matlab simulation.
2020, Vol. 21 
