Transient recovery voltage requirements associated with the application of current-limiting series reactors

This paper describes transient recovery voltage (TRV) requirements for switching devices used in the application of current-limiting series reactors. For fault current-limiting reactors, the series reactor is used during high fault current conditions. During these conditions, the line breaker is required to interrupt faults that may occur on the line-side of the reactor. For load current-limiting reactors, the series reactor bypass switch is normally closed and is opened to insert the reactor if the load current exceeds the line ampacity. For this situation, the bypass switch must interrupt the load current as it transfers from the switch to the series reactor. The study approach and modeling techniques described in this paper examine TRV requirements for circuit breakers and bypass switches to address (a) TRVs exceeding the rating of the line breaker following the interruption of a fault current, and (b) TRVs exceeding the bypass switch capabilities during reactor insertion. The study results are compared to ANSI/IEEE TRV Standards and corrective actions recommended, including control of series reactor natural frequencies. Effects of variations in the series reactor impedance, variations in bus-fault duty, and impacts of wave-traps and current chopping on TRV are described in the investigation. The results of the study provide guidance for the application of line breakers and bypass switches associated with the installation of current-limiting series reactors.