Research On The Control Technology Of Grid-connected Photovoltaic Inverter Parallel System

The grid-connected PV power has become an important direction in the field ofnew energy development and utilization,having a bright prospect of development,asthe inverter is one of the most key equipment in the grid-connected PV system,itsperformance has the important meaning to improve the PV power efficiency andreduce the cost,the capacity of single module inverter is limited, In order to meet thedemand for large capacity inverter system,at the same time,to improve the powersupply’s reliability and the maintainability of the system,we often use the invertersparallel technology.In addition,with the rising of high-performance digital signalprocessing chip (DSP),it becomes possibly to using some advanced control strategysfor the grid-connected PV inverters parallel system.This paper is under thisbackground,to make a more in-depth research for the grid-connected PV invertersparallel technology, and having the important practical meaning.In this paper,we firstly establish the equivalent model of the inverters parallelsystem,analyze the circulation and power characteristics of the inverters parallelsystem,and comparing several typical inverters parallel control mode, making a keyresearch on the technology of parallel inverters based on without interconnect.According to the characteristics of grid-connected PV system and the limitation oftraditional inverter parallel control strategy,we improve a control method of parallelinverters based on without interconnect which is fit for the grid-connected PV system,meanwhile,to carry on the design of two-stage grid-connected PV inverter, equallygiving the design method of control parameters and output filter parameters,thenaccording to the total control scheme of the system, to carry on the hardware designand software design for the system which use the TMS320F2407ADSP as the controlcore, finally,we make a simulation analysis on the improved control strategy,thesimulation results show that the system has obvious balanced current effect,andpossess higher stability and good dynamic performance.