The Research Of Control Strategy On Multiple Single-phase Photovoltaic Inverter Operated In Parallel

With the global energy crisis and environmental pollution becoming more and moreserious, the new energy power generation technology is increasingly becoming a focus forresearchers. Photovoltaic technology has its unique advantage so that it becomes one of thedominant modes of the new energy generation, owning a huge developmental prospects. Withpeople’s increasing demand for electricity,high requirements for system capacity andreliability of power supply, single photovoltaic device has been difficult to meet therequirements, so it is of great significance to conduct research on the photovoltaic parallelinverter system.This paper takes the inverter parallel system which contains two single-phase PVinverter as the research object to study the control strategies of multiple inverters operated inparallel. At the same time, the experiment platform of two2kW single-phase PV invertersoperated in parallel is built in the laboratory.Firstly, this paper established a mode of single-phase photovoltaic inverter which is anonisolated structure of two-stage topology. The circuit parameters of the former Boost circuitand the latter inverter circuit are also designed in detail. For the designed circuit, an integratedcontroller for the decoupled former and latter circuits is also designed and analyzed indetail.At the same time, simulation verification is also done.After the establishment of a single-phase photovoltaic inverter model, this paperestablished an equivalent circuit of the inverter parallel system by taking a parallel invertersystem which contains two single-phase PV inverters as the research object. Through theequivalent circuit, the circulation among multi-inverter parallel system was analyzed in detailand a simulation analysis was carried out by using Matlab/Simulink simulation platform. Forthe case of multi-inverter parallel system with nonlinear loads, a control strategy based onfrequency-divided virtual resistor is proposed in multi-inverter parallel system and acomparative simulation analysis was carried out between the traditional control strategy andthe proposed control strategy by using Matlab/Simulink simulation platform.Finally, the hardware circuit and the software flow of the control system are designed indetail, the experiment platform of two2kW single-phase PV inverters operated in parallel isbuilt in the laboratory. Through prototype experiment, the proposed control strategy isverified by experiment. The results shows that: the proposed control strategy can significantlyimprove the quality of the multi-inverter parallel system’s output voltage, thereby inhibitingthe circulation between the inverters and achieving precise allocation for the inverter’s power, effectively improving the multi-inverter parallel system’s performance with nonlinear load.