Research On Photovoltaic Grid-connected Inverter Technology Based On DSP

With the development of society, energy shortages and the deterioration of ecologicalenvironment have become an increasingly prominent problem. To develop less polluting,renewable energy has become the focus of the countries energy strategy in the21st century.The advantages of clean, evenly distributed, rich make solar energy become the focus of thecountries in the development of new energy. And the decline in the cost of solar cells to makephotovoltaic (PV) technology has been developing rapidly. Grid-connected PV technology isthe main direction of solar power. This article studies the topology and control methods of thelow-power photovoltaic grid-connected system, and elaborates the design of hardware andsoftware in low-power photovoltaic grid-connected system.Firstly, the article describes the curve characteristics of the photovoltaic panels, and theestablishment of the simulation model of the PV panels. Through the analysis of thedrawbacks of conventional MPPT algorithm, proposed a new and improved algorithm, whichcan effectively prevent the phenomenon of the power generated by the system when thechange in the external light misjudgment.Secondly, the controller of this inverter control method to do a detailed analysis, thechoice of voltage and current double loop control. Outer voltage loop is used to stabilize theinverter DC bus voltage, the inner current loop is used to adjust the output current of theinverter, and the use of digital technology real-time detection of the frequency and phase ofthe grid voltage, such that the output current of the inverter and the grid voltage samefrequency and phase. To prevent the grid current of the grid voltage changes, the article usesthe grid voltage feed-forward technology.Then, for a two-stage control structure used in this paper, to build a hardware testplatform, which includes: the previous level DC/DC circuit, after stage inverter circuit,analog sampling circuit, drive circuit, circuit protection, and articlethe important parametersfor the selection of methods to do a detailed calculation. Finally, based on DSP on the the MPPT module and the subsequent stage inverter circuitmodule software programming, collected on the output voltage and current values of thebattery plate and the inverter output current and voltage and the grid voltage signalsampling,signal input DSP in the main program, be programmed to perform MPPT functionand inverter output current same frequency and phase with the grid voltage. Algorithms andhardware circuit is designed in this paper given at the end of photovoltaic grid-connectedsystem simulation graphics and hardware output waveform to prove reasonable.