The Research Of Photovoltaic System Interconnection Control Strategy And Its Application

The failure in large-scale grid-connected photovoltaic system can cause harmonic pollution and the problem of reactive power compensation, which may hurt the reliability and stability of the whole system. Consequently, this paper focuses on the problem of harmonic pollution and reactive power compensation. Precisely, we set up a mathematic model about the transient characristics of photovoltaic system, and investigate the control strategy on two-stages grid connected photovoltaic system in case of failure. Simulation results verify that the Proportion Integration(PI)-Proportion Resonant(PR) control method in the application of voltage is able to reduce the reactive power compensation and harmonic suppression. Specific work content is as follows:Firstly, we theoretically investigate the work principles of the photovoltaic array, booster circuit, and grid inventor. Based on the analysis of the traditional classical Maximum Power Point Tracking(MPPT) control method, we propose the adaptive variable step length conductance increment method, which is used to achieve MPPT of photovoltaic system. Simulation results in MATLAB/SIMULINK verified the superiority of the proposed strategy.Secondly, we compare the control theory of PI and PR in photovoltaic system. Accordingly, we propose the PI-PR control strategy to combine their advantages. The performance of PI-PR control strategy is compared with PI and PR via simulation in MATLAB/SIMULINK, and simulation results verify the feasibility of control strategy of PI-PR.Finally, we simulate the PI-PR control strategy in the application of LVRT in MATLAB/SIMULINK. Simulation results show that the PI-PR control strategy is not only able to restrain the higher harmonic current in fault, but also able to quickly issued a reactive power. In conclusion, this work is meanful for the study of the photovoltaic system low voltage across and the harmonic suppression technology, which is very important for the control of photovoltaic system.