Research And Design On Grid-Connected Inverter For Wind Power Generation System

In order to relieve the pressure of electricity and protect the ecological and social problems, with the concept of the "energy saving and environmental protection" is put forward, new energy power generation has attracted international attention, it will become a vital form of power generation. The grid connected inverter is the important energy conversion medium of the wind energy, which is essential in the reasonable design for the guarantee of the power generation efficiency and the power quality optimization. This article studied the low voltage grid connected inverter from the aspects of principle analysis, research on control strategy, the design of main circuit and control circuit, modeling and simulation, and experimental design.Firstly, the theoretical analysis of the grid connected inverter of wind power generation is analyzed. First of all, the inverter principle and control technology are analyzed, and then the operation process of grid connected inverter system is analyzed, then the mathematical model of grid connected inverter is established, a mathematical model is established in the three-phase static coordinate system, equivalent model of two phase rotating coordinate system, and model under small signal disturbance.Secondly, the disadvantages of traditional control theory are analyzed, then the control theory of instantaneous reactive power theory is introduced, and the active power and reactive power are derived in the three-phase coordinate system, two-phase stationary coordinate system and two-phase rotating coordinate system, so, the application of instantaneous reactive power theory in the control of grid connected inverter system is determined. In the control aspect, the current inner loop and the voltage outer loop of the system are regulated by PI,and the theoretical analysis of the open loop system and the closed loop system shows the importance of the PI regulation.Again,according to the theoretical analysis, the overall structure of the grid connected inverter is designed, and the corresponding parameters are proposed, then the theoretical analysis is made on the parameters of the main circuit of the system to be designed, include the selection of DC side capacitor and the selection of AC side inductance are analyzed. In the control aspect, the TMS320F2812 chip is used as the core component of DSP, then the hardware design of the control system is carried out, include DSP and its basic peripheral circuits, DSP power circuit and reset circuit, JTAG simulation circuit, external extended RAM circuit, A/D sampling circuit, D/A conversion circuit, CPLD circuit, zero crossing detection circuit, current sampling and processing circuit, voltage sampling and processing circuit, PWM signal generating circuit, inverter driver circuit. And then the design of control system software is carried out, include the design of main program, design of interrupt service routine, and the design of generating SPWM wave.Finally, the grid connected inverter system is modeled, simulated and analyzed with MATLAB simulation software in SIMULINK environment, the simulation results meet the design criteria. In addition, a prototype of grid connected inverter controller based on 12KVA/220 V is designed in the laboratory, and the actual operation waveform is recorded and analyzed, so the rationality of the design scheme is verified.