Non-setting Fault Line Selection And Fault Section Location Method For Single-phase Grounding Fault In Smart Distribution Grid

The distribution systems of China are in the high speed development period.Meanwhile,the operation condition of the distribution systems is complicated increasingly.The flexible operation condition proposed great challenges for the design of the relaying protection system of distribution systems.When fault occurs,the rapid and accurate fault diagnosis and fault section location is the basis of fault isolation,fault removal,load transfer and power recover.And it is of great significance for the reliability of power supply.However,most distribution systems of China are neutral ineffectively earthed power systems(NIEPS)in which the fault features of single-phase grounding fault is weak.Therefore,the fault line selection and fault section location are difficult to realize.Firstly,the research situation at home and abroad of fault line selection and fault section location in NIEPS were introduced.By comparing the advantages and disadvantages of various protection methods,the introduce of fuzzy clustering analysis into fault grounding protection is proposed.By studying the generation mechanism of various fault features,the transmission and distribution rule of fault features is revealed.The non-setting fault line selection scheme is proposed.Through gathering the fault information under different operation states and fault conditions and extracting the fault features to form the feature samples,the historical feature sample set were divided into fault group and non-fault group by fuzzy clustering algorithm and the cluster center were obtained.The fault diagnosis was realized by comparing the distances between the real-time feature sample and the cluster centers.The non-setting fault section location scheme is proposed.Various features were selected to form the detected feature samples,all FTUs in the distribution systems were divided into fault group with obvious fault information and non-fault group with indistinctive fault information.The fault section location was realized by affirming the fault information source section.A 35kV NIEPS is simulated with wide variations of operating conditions,non-linear loads and complex fault cases by PSCAD/EMTDC simulator.Results showed that the proposed non-setting fault line selection and fault section location schemes can protect the system correctly under all kinds of faults.Theoretical analysis and simulation results show that the proposed non-setting fault line selection and fault section location method can fuse various fault features to describe the operation condition of the protected feeder from multi-dimensional perspectives and the accuracy was increased.The multi-dimensional fault feature space was established to measure the similarity between the feature samples and to self-adaptively determine the attributes of the samples then.The distances between fault feature samples were selected as the protection criterion instead of setting value.The fault line selection and fault section location can be realized under different operation conditions and fault conditions.The protection scheme has strong self-adapt ability and robustness.