Research On The Control Strategy Of Single Phase Grid-connected Inverter In Wind Power Generation System

The energy crisis has accelerated the human to the research and development of renewable energy, wind power generation has developed into one of the ways of power generation which technology is the most mature and has the most development potential in renewable energy.This paper has researched the control technology of single phase grid connected inverter and its related issues aimed at medium or small wind power generation system. Grid-connected system adopts AC-DC-AC structure, this paper studies the level DC-AC transform, does the overall design to the single-phase grid-connected inverter, each function module unit is also introduced in detail. Inverter circuit adopts the single phase full bridge structure, the working condition is analyzed, the turn-on and turn-off of switch tube is controlled by using the bipolar SPWM modulation technology, gives the design method of the main circuit device selection.Single phase grid connected inverter based on the mode which is voltage source input and controls current output, analysis their respective characteristics of indirect current control and direct current control, and introduces two kinds of commonly used direct current control method:hysteresis control and triangular wave comparison control. This paper adopts the triangle wave comparison control, built mathematical model of the current closed loop control system. Aiming at the shortcomings of the conventional PI controller, analysis the advantages, structure model of the quasi PR controller, and set up simulation model respectively according to the two controllers, make the comparison to their steady performance and the ability response to the disturbance of grid, the simulation results show that the control strategy is feasible.This paper gives the design method of specific hardware circuit of each function module in a single-phase grid-connected inverter, and introduces the software design ideas. For the realization of grid-connected current with the same frequency and phase to grid voltage, the design of phase locked loop is very important. This paper introduces several methods of design of phase locked loop, and this design using DSP capture grid voltage rising edge to realize the PLLFinally, according to the design idea, built the experimental platform, debugged the hardware circuit, measured various output waveforms, and aimed at the phenomena in experimental process, analysis its causes and the hardware circuit is improved. The experimental results show that, the hardware circuit can run reliably and the control strategy is feasible.