Development of a transient stability protection system for Eskom´s Matimba power station

This paper describes the special protection system that was developed for Eskom´s Matimba power station (South Africa). The power transfer of the Matimba interconnected power system is limited to 90% of the station´s full load output capacity due to the fact that faults on the power system will lead to network pole slipping and network breakdown at higher loads. The conventional solution of increasing the tie line strength or installing more lines was every expensive and an alternative solution had to be found. By implementing “generator dropping” or tripping a generator on severe faults, network pole slipping can be prevented. The protection scheme detects when faults on the power system will lead to a network pole slipping and disconnects a generator/s as well as trip line reactors, ensuring stable operation