Research On Resonance Mechanism And Sup-Pression Strategies Of Multi-Inverter Grid-Con-Nected System With Effect Of Delay

With the increasing amount of fossil energy,energy crisis and environmental problems are imminent,so demand for renewable energy is gradually increased.In recent years,with the increase in the scale and grid capacity of renewable energy,multiple inverters are often needed,but this will also make harmonics in the grid more serious.And because the inverter often uses a digital control system,it is inevitably caused the array of control delays,thereby exacerbating the harmfulness of harmonics,resulting in a decrease in the stability of the system.Therefore,the multi-inverter also needs to consider the influence of the number of control delays in the system.This article is based on the digital control multi-inverter grid network system as the research object,and discusses in-depth discussion under the influence of CNC delay.The resonance mechanism of the multi-inverter grid network system,and targeted the strategy of resonant suppression,providing a certain theoretical guidance and technical support for multi-inverter stabilizing and running.Based on the in-depth analysis and research of the digital control delay,the number of control delays is physically and chemically contribute to the grid-connected inverter in the S domain.Therefore,in the case of interactive approximation and approximation,use secondorder Pade Approximation to meet the reaches of delay,and establish a Norton equivalent model of a single inverter grid on this basis.The Norton Equivalent Model of the Multi-inverter grid system is obtained in parallel with an equivalent model of a single grid-connected inverter.According to the modeling of the multi-inverter grid network system,the effect of the inverter itself,other inverters,and grid on the inverter electrical network side current is analyzed.The study laid the theoretical basis for further investigation of the effects of stable operation in multi-inverter grid network systems.As the grid capacity increases,the plurality of inverters meet the demand while also leading to the complexity of resonance in the system,and the existence of several control delays will exacerbate the impact of resonance,which is destroyed to the system’s stability operation.So,the Norton equivalent model of the multi-inverter grid network system is used to study the effect of the harmonic mechanism of the multi-inverter and the frequency domain analysis method.The results show that with the increase in grid,the low frequency resonant frequency in the system is lowered,and the high-frequency resonant frequency will not be affected.The impact of the resonant mechanism of the multi-inverter grid network system is studied in the multi-inverter,and the resonance suppression strategy of the multi-inverter grid network system is conducive to the multi-inverter stabilize and operate.Provide certain theoretical support.To effectively inhibit the number of inverter systems to stabilize the operation of the multiinverter system,this paper is based on the principle of recursive impulse response,and a type ⅡR capacitor current feedback active damping control method can effectively expand the damping area.Compared to the traditional capacitance current feedback active damping control method,ⅡR type capacitor current feedback active damping control has a greater effective damping area,which can fully ensure the stability of the system grid-connected operation and a high thunder resistance of the power grid impedance.The proposal of the resonant suppression strategy is of importance to the promotion of grid-connected power generation technology.