On-line evaluation and verification of protection relay settings - design and field experience

This presentation describes a system that has been developed for on-line evaluation and verification of protection relay settings based on the advanced information and computer technology. The inputs to the system are real-time topology and operation data of electricity networks from the energy management system (EMS), and protection settings obtained from relays. The relay settings are evaluated by simulating various faults on the real-time topology of the networks. It can check the sensitivity and selectivity of the main and backup protection settings. The evaluation results are then displayed in a visualization window on a workstation. If a setting value is found to be incorrect or inadequate, an alarm is raised and a new setting is recommended. The operator can then change the setting or adjust the network operating mode to minimize the risk of protection mal-operations. This system has realized the online checking for the reliable operation of protection relays, and early warning of any inadequate protection settings. The system has been installed in a distribution network in China Southern Power Grid. Since it is in operation in December 2013, its performance is satisfactory.