The Research On Grounding Fault Location Of Feeder In Distribution Networks

Distribution power systems in our country are almost ineffective grounded systems, it is called Small Current Neutral System(SCNS).But the unique characteristics of ground-faults of the SCNS make it difficult to locate exactly the fault point of transmission lines.Based on the analysis of the transient and stable features of fault information on line in single carrier power supply with ineffective grounding neutral, this paper puts forward a new method for fault location in small current power system called "Gradual Identifying Law". It includes four criterions of locating fault point–"Transient zero sequence current Amplitude law","Stable Base wave zero sequence current Phase law","Stable seventh harmonic zero sequence current Phase law"and"S injection law". Pointing out how the Law locate the fault point to minimal fault section by applying these criterions gradually. The law will not only make up the blemishes existing in current methods for single-phase fault location in small current grounding system, but also locate the fault point to minimal fault isolating unit on fault line. And this paper structures the emulation model of 10KV transformer substation by utilizing MATLAB toolbox, emulations the fault course when single-phase ground fault occurs in the small current earth system. And validates the validity of the "Gradual Identifying Law".This paper Makes a deep research in the software and hardware realization of fault location system with radial feeders, stressing on the design of the hardware system and software programming scheme. As to the hardware designation of the location device, this paper evaluates the functions and dependability of the device. Adopting TMS320F2812 as the host computer and C8051F040 as the sub computer, this paper designs a complete hardware system and also makes a detailed designation on each modules of the hardware. As to the software designation of the location device, this paper gives the scheme of the location software, and designs the flow chart of the host computer and the sub computer. This device which is designed on the basis of "Gradual Identifying Law" has such characteristics as accurately locating the fault point, being simple to operate and having a good adaptability.