Case study in improving protection system reliability with automatic NERC PRC-005 inspection, testing, reporting, and auditing

Abstract

This paper is a case study of the design process and validation of a simple and effective solution to satisfy the North American Electric Reliability Corporation (NERC) PRC-005 protection system maintenance program (PSMP) requirements. The example solution is a protection system monitoring (PSM) application for an in-service system at a hydroelectric generating station. This PSM system uses simple digital communication to collect information from intelligent electronic devices (IEDs) to perform real-time validation and status reporting to keep components in working order and to quickly restore the malfunctioning components to proper operation. The PSM controller and all communications are separate from protection and supervisory control and data acquisition (SCADA) communications channels to prevent the possibility of affecting these communications channels. Control is not possible via the PSM communication, and the links are safely added to in-service systems, which simplifies conformance for existing plants. The PSM controller has a real-time operator interface that provides an up-to-the-second audit status of compliance, detected anomalies, and true alarms. The embedded maintenance program automatically performs all of the possible PRC-005 maintenance program activities, including the following: ; Verification - a means of determining that the component is functioning correctly. ; Monitoring - the observation of the routine in-service operation of the component. ; Testing - the application of signals to a component to observe functional performance, observe output behavior, or diagnose problems. ; Inspection - an operator interface to present visible signs of component failure, reduced performance, and degradation. ; Calibration - the recommendations for and confirmation of the adjustment of the operating threshold or measurement accuracy of a measuring element to meet the intended performance requirement. ; Upkeep - the routine activities to ensure that the component remains in good working order and ensure the visibility of any hardware and software service advisories that are relevant to the device application. ; Restoration - the description and acknowledgement of the completion of actions to restore the proper operation of malfunctioning components. Critical protection system components, including potential transformers, current transformers, relays, controllers, station dc supply, and communications channels, are automatically monitored for function and accuracy. The system includes the automatic collection of event reports and disturbance records to provide enterprise-level event storage and analysis. The system is scalable in size and function. A discussion of future enhancements, such as trip circuit validation, is included in this paper. The isolation of the PSM system from the protection, control, and monitoring (PCM) network operation is also discussed to address system security. The system was tested using the design of an actual hydroelectric generating station. The test also included a full simulation of the system. Two major distinctions between traditional protection system maintenance and the testing performed by the PSM system are the automatic and the continuous nature of the reporting. The PSM system constantly performs evaluations on in-service equipment, evaluating and reporting the overall system health. The PSM system not only improves the overall reliability of the bulk electric system by performing real-time evaluations of critical protection system components but also reduces or eliminates fines due to a missed test.