Research On Operational Control Strategy Of Photovoltaic Storage Micro Grid Based On Multi-agent In Off-grid Mode

Microgrid is an effective way to integrate photovoltaic power generation into large grid.Because the photovoltaic power generation is easily affected by the weather and other external environment,and the controllability is weak,the charging and discharging control of energy storage unit is needed to maintain the stability of bus voltage and ensure the balance of power within the micro grid.In this paper,the off-grid optical storage micro grid is taken as the research object,the hybrid energy storage system is built in the single micro grid,the maximum power point tracking algorithm of photovoltaic power generation in the micro grid and the control strategy of the hybrid energy storage unit to maintain the dc bus voltage stability are analyzed.The economic dispatch between energy storage units and net load in a multi-microgrid is also studied.The main work is as follows:Firstly,the overall framework of the photovoltaic storage microgrid system based on MAS is built,and the equivalent models of photovoltaic cells,lithium batteries and super capacitors in the system are analyzed.In the photovoltaic cell,the traditional Boost circuit is improved,a double parallel Boost circuit is established,and a maximum power point tracking algorithm based on fuzzy control in asymmetric universe is proposed.The simulation results show that the proposed control strategy can effectively reduce the ripple amplitude of voltage and current,and has good tracking performance.Secondly,based on the performance analysis of lithium batteries and super capacitor,a hybrid energy storage system model is built to complement the advantages of the two systems,and then an energy allocation control strategy aiming at stabilizing DC bus voltage is proposed.For the control of lithium battery,the double closed-loop control system of power outer loop and inductance current inner loop is used to realize high-power charging and discharging function;For the control of super capacitor,the double closed-loop control of voltage outer loop and inductance current inner loop with fuzzy control is adopted to realize the function of "peak-shaving and valley-filling" for the output power of lithium battery.Simulation results under different conditions show that when the external conditions change,the control strategy can achieve rapid dynamic response and maintain the stability of dc bus voltage in the micro grid.Finally,under the framework of MAS system structure,a consistency-based economic dispatching method for multi-microgrid is proposed to solve the economic dispatching problem between net load and lithium batteries in multi-microgrid.Consistency includes information consistency in the system and consistency algorithm by introducing Lagrange multiplier.The simulation results show that the economic dispatching method proposed in this paper can adapt to the change of environment and realize the optimal economic dispatching of energy.