Research On Fault Diagnosis Of DC Power-supply System In Substation

As the main power supply of secondary system in substation,DC power supply system plays a crucial role in secondary equipment`s safe and stable operation of dc system.In the event of DC system failure,the breaker may reject to work or not work normally,which gives rise to heavy damage to the power grid equipment.Therefore,this paper analyzed the fault diagnosis of DC power supply system in intelligent substation.First of all,this paper studied secondary circuit,the structure of power supply,DC working mode,typical design of DC power system in intelligent substation.Secondly,the fault reason,type and fault mechanism of DC power system components and secondary circuit were studied,which laid the theoretical foundation for fault diagnosis.Again,the fault diagnosis method of DC grounding fault were studied,through the comparison of advantages and disadvantages of five kinds of fault diagnosis methods,the method of resistance balance and imbalance bridge method was presented to measure the bus grounding resistance in this paper.The method of the combination of the resistance balance and dc difference value was adopted to achieve branch feeder grounding fault diagnosis.And then the circuit of bus bar grounding fault diagnosis and branch feeder grounding fault diagnosis were designed.Then,optimizing strategy of faulty line detection was proposed based on event-driven,the core idea of the strategy was to dynamically adjust the next step according to the results of last step,which can adopt the unbalanced bridge method dynamically and minimize disturbance to the DC power system.It analyzed faulty line detection process and verified the efficiency through analysis of examples.Finally,it studied the design of dc power system fault diagnosis platform and put forward the hierarchical design.The platform can be divided into acquisition layer,communication layer and monitoring layer.The function of each layer was designed and the modular design of the acquisition layer was proposed.In the design of communication layer,it proposed that the TCP/IP protocol will be converted into a positive C61850 statute.In the design of the monitoring layer,the system upgrade based on event-driven grounding line optimization strategy and logic requirements.