Analysis and Operating Experience for Back-to-Back 115 kV Capacitor Banks

This paper describes design studies, protective relaying, operating experience, and an automatic control system for a 115-kV capacitor installation involving back-to-back capacitors. The design studies evaluated switching concerns and equipment requirements for the installation. The paper details concerns which are unique to back-to-back capacitor installations. The automatic control system is designed to implement switching strategies based on power flow levels, system voltage, and equipment protection. The operating experience includes switch restrikes which are suspected to have caused equipment failures. These restrike transients are analyzed and solutions to the problem described.