Research Of Z-Source Grid-connected Inverter Based On Photovoltaic System

In future, the photovoltaic power generation technology and development tendency is the Photovoltaic (pv) Grid-connected System, the grid-connected inverter play an very important role, therefore, the essence of photovoltaic technology is grid inverter research, it has been the important subject in photovoltaic grid technology is the research on grid inverter circuit topology and grid-connection control. Based on the Z source grid inverter, this paper launches a research of its circuit topology and grid-connection control strategy.Firstly, this article briefly introduced the photovoltaic grid-connected technology, make the role of gird inverter clearly, after compared with traditional inverter, because of the Z source inverter’s unique X network, it allows the inverter bridge up arm and down arm shoot-through, produce low current waveform distortion, allow input voltage variation, controlling the direct duty ratio can realize the step-up and step-down function, so it is widely used in various occasions. But the current of Z source grid inverter is larger in the instant impact, so this article adopted optimized Z source inverter topology structure, namely increasing inductance and switch power tube before the X network, advantage of the characteristics of inductance current can’t mutations to reduce the impact of the Z source grid inverter at startup current. In the thorough analysis the optimization of Z source inverter working principle, then we design PV grid power generation system with it. On the comparison to several grid-connection control strategy, in view of the conventional grid control strategy in the performance is insufficient, complex algorithm and so on, based on the virtual flux direct power control strategy, adapting power closed loop control and directly taking the instantaneous active and reactive power of inverter output as a controlled object. It achieved power fast control response by using the SVPWM switching function with straight as the virtual flux switch table of direct power control strategy. Oriented phase and frequency of the grid voltage accurately, realized the unity power factor of grid connected inverter synchronous operation.Finally, the simulation model of grid-connected system of Optimized Z-source grid inverter is been set up in MATLAB/SIMULINK environment.relying on the existing lOkW photovoltaic grid connected power system, through the analysis of the experimental waveform, Results show that the Z source grid-connected inverter based on photovoltaic power generation, it can live up to the power grid parallel operation.