Research On Active Damping Resonance Suppression Of Grid-connected Inverters Based On LCL

Among them,the issue of energy is exacerbated as a link not to be overloo ked.The goal of peaks,carbon sinks and deep on human life,to accelerate clean clean for renewable energy,distributed systems and successive expansions of si ngle-pilot installed power still need an inverter connected to the grid scenarios i n which the systems increasingly in the inverter system connected to the grid,It s development is rife with resonance the problem of resonance in the operation of inverter systems multiconnected to the grid has therefore become a central po int of research.The LCL type inverter systems were studied to study the topolog y,the stability of the system and the methods of suppression of resonances of th e monoblock and multimachine inverter systems connected to the grid respectiv ely.The main elements of the research are:Firstly,an equivalent model of the davinan circuit was constructed for a sin gle inverter and the law of distribution of the resonance peaks was analyzed for the case where the impedance of the electrical grid varies widely;Simulation cal culations were used to verify the validity of this method.In addition,we build th e Davynam equivalent circuit model for the operation of the multionduleur syste m connected to the network.When the number of inverters in parallel changes,we analyze the phenomenon of resonance peaks of the parallel system.A simula tion model was built using Matlab/Simulink and validated by simulating monomachine and multi-machine systems.Simulation results indicate that the resona nt frequency of the connected system is reduced with the increasing of net induc tance and thenumber of inverters in parallel,which influences the safety of the c onnected system.Secondly,as for the conventional capacitive current feedback resonance su ppression strategy,its control bandwidth is limited after a network impedance m odification,a resonance suppression strategy based on improved PR control has been proposed.The control system structure is modified by adding a compensat or.This structure increases the control bandwidth of the system and increases th e effective harmonic compensation range.When filter parameters change,the fr equency used also varies over a wide range,eliminating the resonances generate d by inverter systems connected to the distributed generation grid.A simulation model has been developed with Matlab/Simulink to verify the validity of this str ategy.Finally,a multi-machine resonance suppression strategy based on enhance d VPI control is proposed for resonance suppression in multi-network inverter s ystems.The method is based on improving the VPI controller.Based on the dou ble closed current control loop,a conductance feedback loop is added to remove the lower harmonic current on the inverter side.It can effectively prevent the ha rmonic current of inverter from entering the network system,so that the resonan ce of the inverter system multi-connected to the network is suppressed.The sim ulation model was developed by Matlab/Simulink.The results show that this me thod can suppress the resonance of the grid-connected inverter and ensure safe a nd stable operation of the grid-connected system.