INNOVATIVE DIGITAL LOW IMPEDANCE BUS DIFFERENTIAL RELAY: PRINCIPLES and APPLICATIONS

Power system busbars are electrical nodes that interconnect several circuits such as transmission lines, transformers and generators. Although the probability of a busbar fault is much lower than for other items of a power system, when it occurs it produces serious consequences for the whole electrical network. High-speed selective bus protection can do much towards limiting the effects of a busbar fault on the system.

An innovative microprocessor based busbar differential relay that offers fast and sensitive operation under internal fault conditions and ensures improved stability during external faults is presented. The relay is low impedance with a biased differential characteristic and includes means to detect CT saturation.

The relay includes 2 separate bus differential zones to cover different bus sections using a dynamic bus replica mechanism that allows for protecting buses with circuits interconnectable between various sections.