Propagation Delay Measurement and Evaluation for SV Based on HSR Networks

Relay protection devices based on sampling and tripping over shared networks, including the switch tree network and high-availability seamless redundancy ring network, have been widely used in smart substations. These networks all have uncertainties in the relay operation system, such as data congestion, delays, errors, and storms, etc., leading errors to sampled value (SV) in digital protection. Therefore, the effective delay measurement and evaluation method over shared networks are important for the reliable relay operation. Based on the principle and implementation of SV propagation delay measurement in shared network, a novel evaluation method of propagation delay measurement is proposed in this article. With this method, the credibility of the delay measurement could be evaluated and the threshold of delay could be adjusted flexibly in engineering. The credibility indicator and engineering threshold method could mitigate spurious tripping and improve the reliable operation in the protection system.