| Usually in the medium voltage grid 3 ~ 66 k V systems in our country,the current flowing through the single phase to ground fault is minor as the fault occurs.Under the influence of the factors,such as the weak fault current flowing,the unstable ground arc,etc,the problem of line selection by using the steady-state component fault device is quite difficult to perfectly solve.Since the 35 k V lines are the major transmission line of Daqing oil field power network,single phase to ground fault occurs more than 170 times per year.In order to solve the problem of fault line selection,this paper focus on the test and measurement research of single-phase earth fault line selection equipment in Daqing power grid 35 k V transmission line.First of all,this paper studies the basic principles of the transient zero sequence current magnitude comparator line selection algorithm and transient zero sequence current active component amplitude comparator Selection Algorithm,as well as the using conditions,combined with the definition of the features band in the algorithm and the capture method of the adapted features band.What’s more,the integrated selecting line algorithm,based on adaptive feature bands and transient zero sequence current amplitude comparator has been proposed,which provides a theory on the issue of single phase to ground fault selecting line in Daqing oil field grid 35 k V transmission line.Secondly,it analyzes Daqing oil field power 35 k V system conditions and the applied scope of small current grounding fault line selection device based on the integrated selecting line algorithm of transient zero sequence current amplitude comparator.It designs the small current to ground fault artificial ground test program,determines the type of fault simulation,fault simulation main parameters and the main content of the test,and shows the simulation methods of different single-phase ground faults in small current grounding system as well.All of them laid the foundation for artificial ground experimentsFinally,based on the experimental design as well as the actual test conditions,single-phase metal grounding,single-phase arc grounding,single-phase instantaneous ground,single-phase high impedance grounding,single-phase low-impedance grounding,single-phase ground through the branches and single-phase through meadows grounding are conducted,and then combined the results of various ground conditions to give a detail analysis.It also studies the practical application effect in small current grounding device of the two single-phase to ground faults in small current system which verifies and proves the feasibility of transient zero-sequence current in the single-phase to ground faultamplitude characteristics equipment. |
