Research On Fast Switching Device For Medium Voltage Distribution Network

With development of the economy,the distribution network is increasingly becoming the key to power supply,and the distribution network system is prone to large-scale impact or switching of non-linear loads,lightning,short circuit and other failures,which will lead to some problems in power quality.In order to ensure the uninterrupted power supply of the power system,it is necessary to switch the main power supply to the Emergency power in time when a fault occurs to ensure the reliability of the power supply.The traditional power supply switching methods are mostly applied in power plants and coal mines.The distribution network contains not only large load capacity but also a large number of distributed power supplies(DGs),which affect the setting devices and how to quickly and accurately detect faults after a fault.Become a necessary requirement for fast switching of power supply.Therefore,based on the traditional power supply switching device,this paper first analyzes the influence of DG on the fast-cutting device,and then uses the improved SSTS-controlled power switching device to not only overcome the control performance of the traditional device,but also reduce the The inrush current generated by the residual voltage,at the same time,proposes a model diagnosis method to diagnose the type of the fault in the power grid.The detected current and voltage are decomposed by the instantaneous symmetrical component method,and the amplitude and phase angle of the voltage obtained are determined and reduced.The fault detection time improves the rate of fast switching and ensures the success rate.The hardware and software flow of the power switch are designed in theoretical analysis.Finally,the simulation and experimental models show that the power switching device can achieve fast switching of dual power supply,and verify the control strategy proposed in this paper.