Improved zone 2 acceleration scheme using sound phase seen impedance

The acceleration of distance protection zone 2 schemes usually relies on the use of a communications channel. This paper describes a scheme capable of detecting the operation of the remote-end circuit breaker by analysing the seen impedance on sound phase elements in the relay. A series of simulation studies have shown that the technique works under a variety of system conditions. It proposed that the technique is used as a backup when the communications channel is unavailable.