Research On Voltage Stability And Control Strategy Of Microgrid

Energy is an important guarantee for social development and human progress.Due to the limitations of traditional energy,clean and green new energy is highly respected.As an important product of the large-scale promotion and application of new energy power generation technology,microgrid has also been widely researched and applied.The microgrid brings together the advantages of various distributed power generation units and can supply power to a certain range of loads,but it is highly affected by environmental factors,and the randomness of internal load switching is also considered,making the microgrid safe and stable.Serious shock.If the stability of the microgrid is not controlled,it will be incorporated into the large power grid,which may cause damage or collapse of the entire power system.Therefore,in view of the stability of the microgrid and its control issues,this topic has completed the following aspects of work:First,for the voltage fluctuation problem of the microgrid bus,a hybrid control strategy combining traditional droop control and deviation control ideas is proposed.A second-order DC voltage deviation control strategy is used to set the upper and lower limits of the voltage deviation,and the real-time voltage and limit values are used.After comparing the deviation,determine the size of the deviation value.When the deviation value is greater than the upper limit deviation,the upper deviation control loop is triggered;in the same way,the lower deviation control loop is triggered,which can achieve dynamic fluctuations within the upper and lower limit values of the bus voltage.Considering the internal droop control characteristics of the microgrid,this control strategy is mainly used for the situation that the DG unit inside the microgrid cannot reduce bus fluctuations by itself,and the voltage of the microgrid is regulated by the energy injected or connected to the large grid to make it in a complex environment.Maintain the dynamic stability of the bus voltage,and build a model in Simulink to verify the correctness and effectiveness of the strategy.Secondly,in view of the voltage stability of the microgrid,based on the second-order DC voltage deviation control combined with the event trigger strategy,a control scheme with a three-layer event trigger structure is designed.In the first stable layer,the bus voltage changes dynamically within the safety threshold,so no additional control is required to maintain the current state of continuous operation;in the second layer of unstable controllable layers,the bus voltage fluctuations in the internal energy storage unit can be The adjustment range,so by frequently switching the operation mode of the energy storage unit,the fluctuation can be adjusted,and the characteristics of peak clipping and valley filling can also be achieved;in the third layer of switching layer,considering the limited adjustment capacity of the energy storage unit,and its own equipment Protection mechanism,so when the voltage exceeds its regulation range,the upper and lower limits of the voltage deviation control are set by the deviation controller to achieve interaction with the large power grid,the bus voltage is stabilized by the super-adjusting ability of the large power grid,and the microgrid is built The model verifies the correctness of the control strategy.Finally,the work done in this article is summarized,and the future research on this topic is prospected.