Research On Pv Grid-connected System MPPT Technology And Double Closed Loop Control Strategy

The increasingly severe problems of energy and environmental issues have led to rapid development of new energy power generation technologies such as wind power and solar energy.But these two kinds of new energy power generation systems are vulnerable to the weather,and the grid-connected inverter is the core part of the grid-connected system,so its reliability is particularly important.Therefore,this paper takes photovoltaic grid-connected system as the research object,and studies the maximum power point tracking and double closed-loop control technology.The photovoltaic power generation system and photovoltaic cell were modeled and analyzed.Based on this,some commonly used MPPT algorithms were introduced,aiming at the defects of poor convergence,anti-jamming capability and possible misjudgment of traditional methods.We propose in this paper,a new Bio-inspired MPPT controller based on the Ant colony Optimization algorithm with a New Pheromone Updating strategy(ACO NPU MPPT)that saves the computation time and performs an excellent tracking capability with high accuracy,zero oscillations and high robustness.In the double-closed-loop control strategy of voltage and current,the power converter system is firstly analyzed,and on this basis,a double closed-loop control system based on discrete sliding mode and robust control is proposed.The advantages of discrete sliding mode control and robust control methods applied in this system are analyzed.Robust servo control is introduced into the voltage outer loop.Discrete sliding mode control is introduced into the inner current loop.The combination of discrete sliding mode and robust control greatly improves the robustness of the double closed loop system and overcomes the traditional double closed loop system.The disadvantage of poor ability to quickly control the current and reduce the steady-state error.Matlab Simulink is used to simulate the whole grid system of photovoltaic power generation.The module of each part of the system is constructed through the Matlab GUI interface,and the DC voltage source based on the DC-DC converter model is used as compensation to solve the problem of solar energy output instability under natural weather conditions.Simulation results show that the double closed-loop control based on discrete sliding mode and robust control can effectively suppress the occurrence of power quality disturbance.In order to prove the superiority and robustness of the proposed ACO NPU MPPT controller,the simulation results were compared and analyzed with the simulation results of traditional methods and artificial intelligence soft calculation methods and other biological heuristics.The obtained results show that the proposed ACO NPU MPPT controller gives the best performances under variables atmospheric conditions.In addition,it can easily track the global maximum power point(GMPP)under partial shading conditions.