Development and Testing of New Equipment for Faulty Phase Earthing by Applying RTDS

摘要

In neutral-isolated medium-voltage (MV) networks, the earth fault arc is typically extinguished by an automatic reclosing function. It causes a short interruption for the feeder in question. The earth fault arc can also be extinguished by using a shunt circuit breaker (SCB) to earth the faulty phase temporarily at the feeding, typically the 110/20 kV substation. The functioning of the SCB does not change phase-to-phase voltages of the MV system. Therefore, voltage breaks or dips to customers or distributed-generation units can be avoided. The SCB is used for reducing the harmful short interruptions experienced by the customers and electricity producers connected to MV or low-voltage networks. This paper describes the development of the modern SCB equipment. Main attention was paid to the development, testing, and prototyping of the novel SCB. The developed algorithm for the faulty phase selection was implemented to the feeder terminal. The prototype equipment, including the SCB, the programmable logic controller, and intelligent electronic device was tested by applying the real-time digital simulator environment. The prototype has also been installed and tested with artificial earth faults in the real network.