Utility Implements Communications-Assisted Special Protection and Control Schemes for Distribution Substations

The City of College Station has implemented highspeed protection at multiple distribution substations using communications-assisted special protection and control schemes (SPCSs). Traditional protection and control schemes negatively impact fault-clearing time, power system restoration time, and equipment lifespan, and they involve significant wiring with associated costs. SPCSs use the state-of-the-art features of microprocessor-based intelligent electronic devices (IEDs) to improve the availability, selectivity, and security of the power system. This paper describes the functionality and benefits of the following SPCSs implemented using multifunction IEDs, rugged logic processors, and protection-speed communications: Fast bus tripping scheme for significantly reduced bus fault-clearing time. Breaker failure protection scheme for shorter breaker failure clearing time. Double-circuit feeder trip scheme for faster clearing of simultaneous faults without causing a substation outage, and stall reclose logic for system availability. Automatic source transfer scheme for higher power system availability.