Study On Voltage Level And Line Protection Of DC Distribution System

With the rapid development of social economy,the electrical load density of urban or industrial park is bigger and bigger.Increasing access of distributed power sources,energy storages and DC loads as well as power supply capacity,variable flow transformation,power quality and space constraints system have become a prominent problem for the traditional AC distribution system.Therefore,DC distribution system has become the research hotspot in recent years.However,DC distribution system is still lack of selection as well as evaluation standard for the voltage level and the first line of defense in safe operation--relay protection strategies.As a consequence,there are important theoretical significance and engineering application value to analyze on the voltage level of DC distribution system and study on the line protection,which is the basis to propose a protection scheme.In this paper,first of all,the concept and the structure of DC distribution system are summarized.On this basis,power supply requirements,insulating ability,and the design difficulty of system are considered in order to study the voltage level sequence of DC distribution system and its analysis method.Under different voltage level,the power supply capacity and radius are detailed calculated.Furthermore,taking advantage of RT-LAB experiment platform to construct a simulation model and carry out the simulation analysis of DC distribution system about the steady-state,load fluctuation and the fault transient process.In the end,based on the analysis of DC distribution system fault characteristics and the thought of parameter identification infer its calculation method of fault location and transition resistance and study its protection strategy in the use of parameter identification.Under the quantities fault simulations in the situation of different types,different transition resistance,different line parameters and different location,test the protection strategy feasibility with the use of parameter identification for DC distribution system.