A New Type of Faulty Line Selection in Distribution Network Based on Improved Model Recognition

The A new type of faulty line selection in small current grounding system based on model recognition is proposed. When single phase grounding occurs in the distribution network, in different frequency range the zero sequence network equations of internal fault and external fault are constructed, then the model error is established. Model error of external fault is far greater than model error of internal fault for faulty line, however, model error of external fault is far less than model error of internal fault for sound line. According to this feature, fault line selection criterion is pro-posed, and no model parameter is required to be calculated. The simulation shows that the principle is not affected by the initial phase angle and transition resistance, and has high reliability.