Utility interconnection and plant distribution protection modernization

This case study documents power system reliability improvement achieved at an industrial gas processing plant using digital multi-function relays. It reviews the power system protection schemes in-service at the utility interconnect, plant generation units and distribution feeder breakers. Utility separation techniques and negative sequence directional overcurrent elements are used to improve energy source selection and distribution system selectivity. The study describes protection programming that provides additional safety features and additional layers of equipment control. Methods to monitor electrical system disturbances and protection quality are presented. Derived conclusions show that multi-function microprocessor systems are capable of providing enhanced protection, control and monitoring.