Determining Method for the Position of Bus Transfer Disconnectors in Substations Based on Current Change Rates and Three-Phase Unbalance Degree

With the advancement of the integrated dispatch-control target mode, the risk of mis-operation caused by insufficient contact of isolating switches has become a significant factor restricting the implementation of programmed operation. Existing monitoring methods have unsatisfactory reliability, especially during hot bus transfer operation, where poor contact of isolating switches may lead to unplanned system outages and enormous load and economic losses. To address this challenge, this paper proposes a novel method for discriminating the position of a substation bus transfer disconnector switches based on current change rates and three-phase unbalance degree. By analyzing data from existing back-end monitoring system, current characteristics of the bus-tie disconnector switches and bus-side disconnector switches during bus transfer operations are extracted. A new criterion for evaluating the position status of disconnector switches is designed to eliminate the influence of external currents on bus system currents. This approach assists operators to accurately identify knife-switches anomalies and provide new criteria for avoiding mis-operation.