Research On Protection Strategy Of Distribution Network Containing Microgrid

Under the social background of the growing scale of power grid development and the more diverse load demand,the distribution network system is facing a huge challenge,which puts forward higher requirements in power transmission,new energy utilization,fault recovery,system stability and power flow balance.Various flexible devices provide an effective way to solve the problem of the distribution network.SNOP is a flexible device that replaces the traditional contact switch.It is connected between the loads of the distribution network and can realize the precise transmission of power at both ends.At the same time,it can rapidly provide voltage support for the load of power failure,and has certain research significance for improving the stability and reliability of the distribution network,which makes the distribution network have the main advantages of radiation network and ring network.Firstly,this paper introduces the functions of SNOP,and determines the scenario of the two terminal distribution network system studied in this paper.The device selection of SNOP is based on B2B VSC type.The working principle is analyzed and the mathematical model is established in d-q coordinate system.The operation status of SNOP is divided into two states:system overload and fault.The control strategy is analyzed and researched.In the case of power transmission,SNOP uses Udc Q-PQ control strategy to ensure the accuracy of power transmission;in the case of power supply for power loss load,it uses UdcQ-VF control strategy to ensure the normal operation of load.Finally,the simulation model is built in Matlab/Simulink,and the results show that SNOP has good control over the power transmission between the systems,and it can also provide stable voltage support for the load when the distribution network fails.SNOP is effective to improve the power supply reliability of the system.In order to enlarge the application range of the SNOP device,the energy storage type SNOP device which combines the energy storage system with the SNOP device is put forward,which can improve the absorptive capacity of new energy.Through the analysis of the energy storage system,it establishes the relationship with the SNOP,and carries out the charge and discharge control through the appropriate control strategy in cooperation with the SNOP.At the same time,the control strategy of the SNOP is modified.The charge and discharge of the energy storage system cooperate with the control of the rectifier converter to stabilize the DC voltage when the load changes many times.Add real-time load power feedback to power control,track load changes,and achieve accurate power control.Finally,the simulation analysis in Matlab/Simulink verifies that the access of the energy storage system has certain significance for the suppression of DC voltage fluctuation,power supply and new energy consumption.Figures[52]Tables[5]References[66]...