Research On Maximum Power Point Tracking And Control Strategy For Grid-connected Of Photovoltaic Power Generation

To address the problem that the efficiency of photovoltaic power generation and the quality of power connected to the grid in a two-stage,three-phase grid-connected photovoltaic system do not meet the desired requirements,this article has presented a maximum power point tracking control method in consequence of on the combination of improved bat algorithm and disturbance observation method and a grid-connected inverter control method in view of improved sliding mode control,and the chief study contents are as below.Firstly,the constituent form of two-stage PV grid-connected system is analyzed.The working principle of PV cell is explained,and the effect of temperature and light intensity on the output performance of PV array under uniform light and partial shadow conditions is simulated and analyzed;use the boost circuit to implement the maximum power point tracking;building a mathematical model of a grid-connected PV inverter;LCL-type filter arguments and resonance suppression are studied.Then,for the problem that the PV array output curve under local shading presents multiple peaks and The inability of conventional maximum power point tracking algorithms to track the maximum power point,this article brings forward a maximum power point tracking method so as to an integration of improved bat algorithm and perturbation observation method.A chaotic optimal bat-based algorithm for initializing populations and improving population diversity;introduces adaptive inertia weights and Lévy flight,which are beneficial to jump out of local extremes;and then shrinks the convergence range by dynamically shrinking the interval.The combinational algorithm first uses the modified bat algorithm to follow to close to the maximum power point,and then change to using Perturbation observation method to find the maximum power point taking advantage of the fact that it convergence fast.Matlab/Simulink simulation analysis shows that the combinational algorithm can track to the absolute optimum at express speed and precisely,verifying the superior tracking performance of the composite algorithm.Finally,to address the problem that the conventional control of LCL-type gridconnected PV inverters has failed to achieve the desired system control performance,this article has presented an optimised doal-closed-loop sliding-mode control method.Integral sliding surfaces designed to ensure the overall robustness of the system;the voltage loop introduces the P-order parametrization of the state variables based on the traditional exponential convergence law to adaptively adjust the system motion speed;the current loop adopts the second order sliding mode control combined with superhelix algorithm to integrate the discontinuous terms in the convergence law,so that the output control quantity is continuous.The simulation results with MATLAB/Simulink show that the proposed method can suppress the chattering of sliding control,improve the power supply quality and improve the robustness of power grid.