Research On Z/Q-Z Source Inverter Photovoltaic Grid System Based On Deadbeat Algorithm

Photovoltaic power generation is the main way of development and utilization of solar energy which core is the maximum power point tracking and power grid connected inverter, and improve the quality of grid connected power. It has huge potential and immense prospects.Z source inverter utilizes "X" type capacitor,inductor network to achieve buck-boost conversion, not only improve the efficiency and reliability of photovoltaic grid connected system, but also reduce the control complexity. The new Z source inverter can greatly reduce the capacitor voltage value of the energy storage net compared with the Z source inverter, thus reducing the volume and cost of the capacitor which is significance in improving economic benefit.Firstly, the photovoltaic cell is analyzed, and the simulation model is built, and the simulation is carried out under different light intensity and temperature, The output voltage, current and power are not the same. Therefore, it is necessary to track the maximum power point of photovoltaic cells in order to improve the efficiency of light energy conversion and output. The maximum power point control is carried out by using the conductance increment method, which can reduce the start impact and make the direct duty ratio increase linearly from zero,The soft start of Z source and Q-Z source inverter is realized.Secondly, in Z source and q-z source inverter, deadbeat control algorithm is studied, for enhancing the Z source, q-z source inverter output efficiency and power quality and reducing the grid connected current harmonic distortion, the algorithm of deadbeat is proposed. Using the algorithm of deadbeat to control the grid, it can achieve single power factor operation and digital control, and has the advantages such as fast response,high efficiency, good power quality, convenient control and so on. The Z source, Q-Z source inverter, and non beat algorithm model are established,and the Z source and Q-Z inverter are connected to the grid by using the deadbeatalgorithm. There is a large DC component in the control of the deadbeat so the DC component needs to be restrained. In this paper, the combination of the grid current compensation and the isolation capacitor is adopted, which has good effect.Finally, by the simulation analysis, the conductance increment method can track the maximum power point, improve the utilization rate and conversion efficiency of the solar energy. Correctness and feasibility of the deadbeat algorithm is applied to the control strategy Z source,Q-Z grid connected inverter, grid connected effect is excellent, grid connected current harmonic distortion rate is less than 1% and q-z source capacitor voltage value decreases half an order of magnitude than Z-source.Soft start control can effectively solve the problem of the start impact on Z source,Q-Z source capacitance voltage, the voltage of the inverter bridge, the start process is stable, and improve the life of electronic devices and the reliability of the system. DC component suppression strategy is adopted which has obvious effect, the grid connected current DC component is less than 0.5% without increasing the grid current harmonic distortion rate of the case,to achieve efficient grid-connected.