Fault Detection Method for Intelligent Distribution Network Based on Protected Element Model

The intelligent distribution network allows a large number of DGs to access. Under the influence of complex fault characteristics of DG and its control strategy, it is difficult for longitudinal comparison principle protection based on fault direction to reliably judge the fault sections. A fault detection method based on protected element model is proposed. This method no longer starts with analyzing the fault characteristics of DG, but takes the mathematical model of the protected object as the breakthrough point. Firstly, an appropriate physical quantity can be defined based on the mathematical constraints of the model. Then, by analyzing the variation law of the defined physical quantity under both the internal and the external fault of the model, the integrity of the model can be judged, which can be used as the basic information for pilot protection to constitute the corresponding fault judgment method. In this paper, the operation voltage is taken as the physical quantity to judge whether the model is intact, and the setting principles of the impedance in operation voltage method is analyzed in detail, so that the method proposed can adapt to the operating characteristics of intelligent distribution network. Simulation results show that the method proposed in this paper is basically not affected by the fault characteristics of DGs, and the comparison of the longitudinal logical results can accurately identify the fault section.