Research On Parallel Operation Control Of PV Inverter System

With the intensification of energy crisis and environmental deterioration,more and more attention has been paid to the development and utilization of new energy.Among them,solar energy has been vigorously exploited and utilized for its rich,clean and environment-friendly advantages.Photovoltaic technology is considered to be the most promising new energy technology,and is gradually becoming one of the leading new energy utilization modes in the future.With the development of industrial production and social life,the demand for capacity and reliability of the power supply system is becoming more and more important,and the single photovoltaic power plant has gradually shown its limitations in its application.The operation mode of parallel inverter can not only greatly increase the capacity of the system,but also make the system redundant,thus it can ensure the reliability and flexibility of the power supply system,and have a great influence on the development of photovoltaic power generation technology.Therefore,this paper chooses photovoltaic inverters parallel operation technology as research content.The parallel control technology of single-phase inverters is studied in this paper.Firstly,the principle of single inverter operation is analyzed,the mathematical model of single inverter is set up,and the LC filter,current inner loop control and voltage external loop control are designed respectively.The output voltage waveform is compensated instantaneously,so the stability and precision of the output voltage is improved.On this basis,the mathematical model of the parallel operation of two inverters is built.The mechanism of the circulation of the parallel inverters system is analyzed in detail.The difference of the amplitude and phase of the output voltage of the parallel inverters is important factor that leads to the circulation of the system,and the different factors that affect the circulation are made through the Matlab/Simulink simulation software.The simulation results show that the difference between voltage amplitude and phase difference can be reduced by adjusting the output power of the system.In view of the traditional droop control only considering the erroneous regulation problem of active frequency modulation and reactive power regulation,the traditional droop method is improved.By taking into account the effect of the output power of the inverter on the output voltage,an improved droop control strategy is proposed and the related parameters in the improved droop control are calculated to improve the operation effect of the inverters parallel system.The simulation model of parallel system is built,and the function and parameter design of each module in the system are introduced in detail.The simulation results show that the improved droop control method can effectively achieve the power sharing between parallel inverters and reduce the circulating current.It provides some technical guidance for improving the safe and stable operation level of inverters parallel system.