On the use of Real-Time transformer temperature estimation for improving transformer operational tripping Schemes

Abstract

During each summer, the super grid transformers (SGTs) inside GB transmission network are maintained according to the schedule which is determined by the asset management strategies. The outage of selected transformer often results in an increased loading on the rest of transformers in the adjacent circuits. Any type of faults occurring on circuits or other elements during this period of time is likely to cause overloads on the remaining transformers which could lead to a breach of the Security and Quality of Supply Standards (SQSS). The transformer operational tripping scheme (OTS) is a technique for protecting transformers from overloading by tripping pre-selected groups of generations so that the loading on the monitored transformers can be relieved during the contingencies. An event-based transformer OTS has been constantly armed in the GB network. This paper presents a novel technique to integrate the real time transformer temperature estimation into an existing transformer OTS. This technique improves the OTS by reducing the number of unnecessary generation tripping, which is initiated from the overly conservative transformer ratings. This novel scheme will generate enormous economic benefits as well as provide significant flexibility to the GB system operator – National Grid Electricity System Operator (NGESO). The new scheme is an example of a Wide Area Monitoring, Protection and Control (WAMPAC) application.