The Power Flow Coordinated Control Strategy Of Microgrid

With the widespread attention to environmental issues,distributed generation technology has developed rapidly.However,the large number of micro-sources grid in distribution network leads to a series of problems.Therefore,the world's countries and standardization committees have developed corresponding standards.In order to solve the contradiction between distribution network and micro-sources,give full play to the value and benefits of micro-sources for distribution network and users,the concept of microgrid emerged as the times require.Firstly,the conception and research status of microgrid and microgrid cluster were introduced,and worldwide research results were summarized.Subsequently,several common micro-sources were introduced,including photovoltaic cells,wind turbines,fuel cells,micro turbines and energy storage devices.Among them,the model of photovoltaic cell is established with Matlab/Simulink and the correctness of the mathematical model is verified.After the micro-source transforms the external primary energy into electrical energy or intermediate form mechanical energy,the output power must be processed by related power equipment interface to meet related standards of grid connection.Therefore,the common inverter interface control methods were introduced,the grid connection and control mode of the micro-sources were introduced.Secondly,the current management and control methods of microgrid were analyzed.On this basis,the power flow coordinated control strategy of wind/solar/storage microgrid based on combination of hierarchical control and energy management was studied.The architecture of the coordinated control strategy and the coordinated control strategy of micro-sources and energy storage during grid connection statues were given.The output power of each micro-source was studied and the simulation analysis was carried out.The results showed that the proposed coordinated control strategy can effectively allocate the output of each micro-source.A function of state was defined by splitting the continuous probability density function of output power of wind turbine and photovoltaic array per hour into multiple sets of states.A new index was defined to evaluate the effect of energy management based on the distributed generation cost.The optimization of objective function was realized by genetic-tabu search algorithm,the allocation of the micro-sources in the microgrid cluster energy management was solved.Aiming at the proposed microgrid cluster energy management strategy,a simulation model of distribution network with micro-source based on PG&E69 bus system was established with Matlab/Simulink.The simulation of energy management of microgrid with or without microgrid cluster control was carried out.Through analyzing the change of daily cost of micro grid cluster with or without cluster energy management,the effectiveness of the proposed method was verified.