Research On Line Selection For Small Current Neutral Grounding

For small current grounding line,which means that single-phase-to-earth fault occurs in small current grounding system,we can use this method to find the fault line and select the wrong one to make sure the power system can operate properly and safely.There has already been methods for selecting the small current grounding line,but it has some disadvantages,such as it’s limited scope and poor reliability.In this regard,the author in this paper uses evidence theory to put forward a new way to solve those problems.First,selecting system information form two aspects,one is the steady state information,the other is transient information.According to the difference between these two kinds of information of the fault line and right line respectively,we can obtain data of selection criterion,high frequency energy and flow direction of transient power.The data are all numerical simulation.We can simulate the data to obtain the fault measures of all lines under different fault types.On the above conditions,according to the actual use space of small current grounding line selection and the definition of evidence theory,we can define the concept of recognition framework,create a suitable credit assignment function for small current grounding line and get three evidence for the fusion.After that,combing with the features of each evidence,we exam those evidence to pick put the appropriate group.In the meantime,we make the line selection decision,and finally get the results.We simulate according to the six kinds of common fault,and find that the new way to select small current line based on the evidence theory after improving the combination rules can find the fault line accurately,.What’s more,the method is stable and reliable and can be applied to many places.lt’s actual value is very high.