Research On Single Phase Photovoltaic Gird-connected Inverter And Its Control

With the increasing scarcity of fossil fuels, the tension of power supply, the deteriorationof ecological environment, the use of renewable energy is imperative. Solar energy as greenenergy has been widely applied, and photovoltaic generation becomes a major way of usesolar energy. The grid connected photovoltaic inverter is the key component of grid connectedPV system, so the research is becoming increasingly important.In this thesis, the purpose and significance of the grid-connected photovoltaic inverter isresearched, the research status is introduced and then the requirements of the photovoltaicgrid are provided. Photovoltaic power generation system structure and the circuit topology isstudied, and the comparative analysis of the advantages and disadvantages of all kinds ofcommon conversion circuit, in the thesis, the system has small and medium-sized power, usesa typical two non-isolated structure, the front stage DC/DC converter selects Boost circuitand the final stage DC/AC converter uses a full bridge circuit. The analysis is focused on theworking principle of the photovoltaic cells and equivalent model, the output characteristiccurve is obtained then the common MPPT control method is also discussed, for misjudgmentperturbation and observation method is provided based on the phenomenon of powerprediction optimization algorithm.The research focus on the grid control technology, the choice of current and voltagedouble-loop control strategy and simulation using MATLAB. For PI control can not eliminatethe exchange volume of the steady state error, the double closed loop control with repeatedcomplex control strategy is provided, so that PV systems have fast response characteristic ofPI control and also have superior steady-state performance of repetitive control, eliminatestatic error.