ON06 – Feasibility of Maximizing Operational Flexibility with Minimal Cost (RMU Close Ring Operation)

Regarding 132kV area transmission network, CLP typically have three configurations (Direct Feed, RMU Radial Feed, and RMU Open Ring). Each configuration obtains its unique characteristics and is deployed to specified scenario. This project aims to fully utilize the existing equipment in RMU Open Ring configuration and further enhance the operational flexibility in power grid. Simply said, this project proposes eliminating the normally open point in RMU Open Ring configuration that two bulk substations will be operated in parallel through plain feeders and RMUs circuits existing. The advantage of such operation is to provide higher flexibility for outage planning and contingency. In outage planning, N-1-1 criterion must be considered before switching off the circuit. Parallel operation aids for increase the maximum allowable substation loading for circuit outage. In contingency, RMU Close Ring Operation provides backup channels for electricity delivery. Such brings significant benefits to the power grid operation. Before implementing RMU Close Ring Operation, several considerations (Maximum Fault Level, Load Flow, and Protection Scheme) must be addressed. Under the use of existing equipment, permissive overreaching transfer tripping scheme is introduced. Although the proposal is technically feasible, the actual implementation subjects to the balance of system security, power quality, and operation flexibility.