DC Power Distribution Network Fault Diagnosis Based On Power Flow Information

With the development of power electronic equipment and distributed energy,the DC distribution network injects a new vitality into the traditional distribution network construction.However,DC distribution technology is still in the early stages of development.The research on the grounding mode,protection scheme and fault diagnosis technology of DC distribution network still needs to be carried out in large quantities.First of all,this paper gives three kinds of grounding system of DC power distribution network by combining the grounding method both of coupling transformer of AC side and the neutral point of DC side.According to the structural characteristics of different grounding system,this paper analyzes and summarizes various grounding modes Under the DC distribution network fault characteristics.Then according to the fault characteristics of DC distribution network,a protection scheme of DC distribution is proposed.According to the characteristics of overcurrent blocking of high current system inverters,a DC distribution network based on the current direction information after the blocking of the converter is proposed Fault isolation scheme,the method can identify the fault section in situ,neither need to calculate the setting nor the control center issued a circuit breaker breaking command,has good speed and accuracy.Finally,a fault diagnosis scheme of DC distribution network based on power flow information is proposed,which is applicable to different grounding modes of DC distribution network.Firstly,based on power flow equation.,The power flow distribution could be obtained quickly and accurately according to the voltage measurement point configuration scheme.The power flow distribution after the fault is predicted according to the power flow distribution during normal operation,and a power flow prediction library is formed.At the same time according to the fault current size of the system is divided into a large current system with small current system,fault current circuit breaker system,rapid action,fault isolation,will lead to distribution network topology changes,computing all possible new topology in the current distribution can generate trend prediction information database,the with the actual trend of information comparison,when the same trend prediction information extracted with the actual flow of information,can be completed online fault diagnosis methods.Forecasting current information is used to predict the changes of each electrical system of the system after the fault occurs.Combined with some measured information in the system after the fault,the fault location is completed.And the feasibility of the diagnosis scheme is verified through simulation.And the method can analyze the relationship between the change of power network structure and the change of power flow information on-line,which is more fault-tolerant and accurate than the fault location based on switch information alone.The method of fault diagnosis to online analysis of changes and trends of network structure distribution,which is rapid and accurate,intelligent features,and with the amount of information to achieve fault location switch has higher fault tolerance.