The Research And Realization Of Single-phase Grounding Fault Location About Middle Voltage Distribution Networks

The middle-low voltage distribution networks mostly adopt neuter point not- valid grounding (be so called to the small current groundding system). The distribution wire fault, particularly the fast and accurate location that the single grounding fault, not only to the repair wire and promise dependable power supply, and circulate to the safe stability and economy that promises the whole electric power system to all have a very important function.Introduced result of small current system to grounding choosing line and research career first, the technique problem that chooses line was basic to have already been resolve, choosing line currently if appear a problem is manage a problem. The middle voltage distribution networks single gruonding fault location is carried on a research to combine to be practical the research result to turn. The main contents in the fault location:(1)Put forward C type travelling wave location method and the low frequency AC location method to combine together, and carry out that method. Travelling wave method to carry on thick location with the C type travelling wave first, the assurance fault distance, position an error margin in 300 meters inside, then adopt the low frequency AC method to carry on a thin location, inject into the AC 60 Hz signal to the fault while have a power fail the appearance mutually, hold the signal detector by hand again to examine the 60 Hz low frequency signal in the 300 meters scope of the error margin, make sure the fault position.(2)At weakness pointed out a C type travelling wave method after, put forward the DC fault location method, and carry out that method. The DC fault location method is to have a power fail on off-line, to inject into the DC signal, then hold the DC signal detector to follow circuit to examine that DC signal, make sure fault concrete position. The main advantage of the DC signal method is the influence that inject into signal to be free from to wire distributing capacitance, so the location is apart from effectively long.At the DC signal examination aspect, put forward a kind of apply in the DC fault location of the wireless data deliver system, the hardware that designed a single slice the machine C8051F310 and nRF 2401 chips connects a people's electric circuit, give the hardware electric circuit of the system design to design and software, make DC detect part and show the part separates to attain a safety of purpose.(3)Give the distribution networks wire distributing capacitance to the influence calculation formula of the AC location method, put forward the AC signal method on this foundation of the choice method of inject current and the signal frequency, make sure the application of the AC signal method, and carry out that method.(4)Put forward the DC fault locatiom method and low frequency location method combine together of integration location method, and carry out that method. The advantage of the AC signal method is a signal to examine easily, the weakness is wire distributing capacitance influence big, but the DC method is exactly the opposite, the advantage of the DC method is free from to wire distributing capacitance influence, the weakness is a signal not easy examination, combine together two kinds of methods to carry out advantage to repair to make the distribution networks fault location come to a with each other practical turn degree.(5)Put forward the phase on line fault location method; Put forward the electric wire post current examination fault location method. The DC location method and integration location method belongs to the off line location method with all, but phase location method and the electric wire post current t measure method to belong to the on line location method, use zero order current detector detect the phase of fault point fore-and-aft current to locate fault.