Research On Maximum Power Tracking And Droop Control Strategy Of Photovoltaic Microgrid System

At present,the development of renewable energy has received worldwide attention.Among them,solar energy has been widely developed because of its rich and clean characteristics,and microgrid has been widely concerned as the most effective integration mode of distributed energy.Therefore,photovoltaic microgrid system based on solar energy resources has become a research hotspot.However,with the developments of photovoltaic power generation and microgrid technology,there are two new problems: one is how to maintain the maximum power point tracking in the complex environment,and the two is how to realize the reliable and stable operation of the microgrid system.Photovoltaic cells are blocked by shadow,resulting in the output P-U characteristic curve showing multi-peak.The traditional MPPT control strategy is no longer applicable,so a compound MPPT control strategy based on PSO and INC is proposed.Among them,the traditional PSO algorithm structure is improved,P-D control is adopted,and the "replace" link is added;the INC algorithm takes variable step size disturbance.The improved dual diode photovoltaic array model is established,and the improved PSO algorithm is used to quickly locate the maximum power point,and then the variable step INC algorithm is used to accurately locate the maximum power point.This method can achieve fast and accurate optimization in complex environment.Because of its output instability,photovoltaic cells adopt PQ control to achieve maximum power output.For the microgrid energy storage device,the droop control is generally adopted,but the droop control has many disadvantages,such as slow dynamic adjustment speed,unequal power distribution of micro-source,and instability of frequency and voltage.A subsection dynamic adaptive droop control strategy is proposed.The droop coefficient is increased by piecewise droop control to improve the dynamic response speed of the system.The droop coefficient is adjusted by dynamic droop control to improve the power distribution effect.Adaptive droop control moves the droop curve to maintain frequency and voltage stable.The control strategy can effectively realize the stable operation of microgrid.Finally,aiming at the photovoltaic microgrid system,an integrated control strategy is proposed based on the above algorithm,which overcomes the shortcomings of traditional master slave control and peer to peer control.Through simulation and experiment,the effectiveness and superiority of the integrated control strategy are verified.