Busbar Differential Protection Using an Alternative Generalized Alpha Plane

Abstract

This paper describes an alternative busbar differential protection function based on the generalized alpha plane. This approach faithfully maps several currents in two equivalent currents such that it preserves the original restraint and operation signals. The original formulation was applied to multi-terminal transmission lines protection but the number of terminals can be small if compared with the number of bays connected to busbars. For this reason, this first method is initially assessed in order to verify its suitability for busbar protection purposes. After that, an alternative algorithm to map the currents in the same plane is described and tested by using a double-bus-single-breaker 220 kV busbar configuration, modeled in ATPdraw. The simulations of internal and severe external faults, as well as evolving faults, are performed for a wide variety of scenarios including fault times, fault resistances and fault types. The results bring up a greater robustness and shorter response time if compared with original alpha plane approach, thus it represents an alternative as a busbar protection function which provides high reliability and it can be easily implemented in a commercial relay due to its mathematical simplicity.