Research On Resonance Mechanism And Suppression Method Of Distributed PV Clusters

With the further advancement of the national energy strategy,the proportion of clean renewable energy represented by solar energy and wind energy in the national energy structure has also increased,and the photovoltaic industry has developed rapidly in this era.Distributed photovoltaic cluster power generation is the main form of solar energy utilization.However,due to the existence of grid impedance and the passive high-order characteristics of LCL filters,distributed PV clusters are prone to resonance in the process of grid connection,which seriously affects the safe and stable operation of distributed PV cluster grid-connected systems.Therefore,the research on the resonance mechanism and resonance suppression method of distributed PV cluster grid-connected system has very important practical significance.In this paper,the equivalent physical model and equivalent mathematical model of a single PV inverter grid-connected system and a distributed PV cluster grid-connected system are established for the structure and control mode of distributed PV cluster grid-connected system.Based on the system equivalent model,the resonance mechanism of a single PV inverter grid-connected system and a distributed PV cluster grid-connected system is revealed and compared.Based on the system equivalent mathematical model,the reasons for the strong coupling of the distributed photovoltaic cluster grid-connected system are explained.The influence of grid equivalent inductance on single PV inverter grid-connected system and distributed PV cluster grid-connected system is analyzed and compared from three aspects: system stability,transient performance and steady-state performance.The simulation results verify the correctness of the theoretical analysis.Based on the equivalent mathematical model of the grid-connected system of distributed photovoltaic cluster and the theoretical analysis results of system resonance mechanism and the effect of grid impedance on the system,the dual-system parameter design method is proposed to meet the resonance suppression and grid-connected performance requirements of distributed PV cluster grid-connected systems.The dual-system parameter design method can meet the requirements of grid-connected performance of single PV inverter grid-connected system and distributed PV cluster grid-connected system.The simulation results verify the correctness of the dual-system parameter design method.