Development of an algorithm for identifying single-phase ground fault conditions in cable and overhead lines in the networks with isolated neutral
The paper addresses the issue of identification of the type of single-phase ground fault in medium voltage networks operating mainly with an isolated neutral . By an alyzing the published research , the most promising method for detection of a single-phase ground fault were selected . Further, using the selected parameters, algorithms were designed to determine the parameters , process them , and use them to identify the type of a single-phase ground fault. The algorithm developed by the authors was formalized for the application on the basis of microprocessor -based protection systems using digital signal processors . The operation process was modeled using real oscillograms of single-phase ground fault. The use of high-frequency zero-sequence current and voltage components, as well as the root mean-square value of the zero-sequence voltage, made it possible to design an algorithm that identifies any of the possible single-phase ground fault types (bolted, arc, or contact resistance ones). The first part of the article gives an overview of the state-of-the-art of research in the field of detection and identification of single-phase-to-earth faults . In the second part , the parameters of emergency operating conditions are analyzed and the key parameters are determined based on them . The third part contains a description of the single-phase fault identification algorithm developed by the authors and the output osci llograms. The fourth part makes conclusions on the applicability of the algorithm.