| The development of the world economy is highly dependent on the development of energy,and the efficient use of clean energy is an eternal topic.In the electricity market,traditional non-renewable energy sources such as coal and natural gas will gradually be eliminated by the market,while distributed generator(DG)of new energy sources such as solar energy and wind power will gradually gain a dominant position in the power market.However,when a large number of distributed power sources are connected to the grid,it will have a certain impact on the power quality of the grid.In order to solve these problems,the microgrid control technology has moved from the laboratory to the field.The microgrid is connected to the grid through a Point of Common Coupling(PCC),and relevant control technology is adopted to make it stably and effectively connected to the grid.When it encounters a fault,it can operate independently from the network.Compared with the large grid,it can be regarded as an independent "load".Therefore,studying the operation control strategy of the microgrid is of great significance for the stable operation of the grid.The specific research contents are as follows:Firstly,the principle of photovoltaic cell and energy storage system is studied,using the simulation model of photovoltaic cell and energy storage system built in MATLAB/Simulink to analyze the operating characteristics of photovoltaic cell,the charge and discharge characteristics of energy storage battery and the structure and control methods of bidirectional DC/DC.The model of the grid-connected inverter is also studied.Secondly,based on the previous analysis results,the operational control strategy of the AC microgrid is studied.To control the inverter,the PQ control strategy adopted by each power supply during grid-connected operation and the V/f control strategy adopted by the energy storage power supply during off-grid operation are designed.At the same time,the black start control strategy,the island detection method and the off-grid switching strategy of the microgrid are also studied.The optical storage microgrid model was built in MATLAB/Simulink for simulation research.The results of three operating states verified the correctness of the designed control strategy.Finally,starting from the actual project,the control strategy of theoretical research is applied to the micro-grid project of a community of Yuxi.By studying the waveform results of the experiment,such as grid connection,off-grid and off-grid switching,it is found that the designed control strategy has achieved the expected results in engineering. |
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