Research On Active Damping Suppression Method Of Cluster Resonance Of Photovoltaic Grid-connected Inverter

Photovoltaic inverter cluster power generation improves the thesis generation efficiency of photovoltaic thesis plants,but its complex structure will cause resonance problems in the grid-connected system,cause the grid-connected current to be distorted,and affect the thesis quality of the grid,and in severe cases,the safety of the thesis system Stable operation.Therefore,it is of great significance to solve the resonance problem of photovoltaic grid-connected inverter clusters.This thesis takes photovoltaic grid-connected inverter cluster system as the research object,and proposes two resonance suppression methods.The main research contents are as follows:First,the system establishes two mathematical models of photovoltaic grid-connected inverters under different coordinates,and derives the output characteristics of the system under different coordinates;According to the characteristics of the influence of different structures on the resonance of the photovoltaic grid-connected inverter system,the problems of different resonance types caused by a single grid-connected inverter and multiple grid-connected inverters are discussed;Based on comprehensive consideration of the inverter power loss,grid-connected current standard,design cost,and resonance characteristics,the influence of filter inductance and capacitance parameters on the resonance characteristics of the grid-connected inverter is analyzed.Then,in view of the high cost and more complex limitations of traditional active damping control structures,an improved active damping resonance suppression method is proposed,add an improved parallel feedforward compensation damper between the filter and the capacitor current feedback,and by forming an active damping loop in the control system,the method reduces the complexity of the control structure and the power loss of the system,and improves the control bandwidth and effective harmonic compensation range,the resonance of the photovoltaic grid-connected inverter system can be effectively suppressed,and a simulation model built using Matlab/Simulink to verify the effectiveness of this method of resonance suppression.Finally,aiming at the resonance suppression problem of photovoltaic grid-connected inverter clusters,a dual-current closed-loop resonance suppression method with active harmonic conductance is proposed,add a conductance feedback loop to the dual current closed-loop control loop,and add active filter conductance to suppress the low-order harmonic current on the inverter side,which can effectively prevent the harmonic current of the inverter from entering the grid system,so as to achieve the resonance suppression effect of the photovoltaic inverter cluster,the simulation model is constructed by Matlab/Simulink,and the results show that this method can safely and stably integrate the output signal of the inverter into the power grid system,which verifies the effectiveness and correctness of the resonance suppression method.