SOURCE:

Faculty: Engineering
Department: Electrical Engineering

CONTRIBUTORS:

Akpeh V. Anthony
Ezechukwu O. A
Madueme T. C

ABSTRACT:

This dissertation proffered ways to mitigate the enormous constant power losses encountered during implementation of Current Limiting Reactors (CLRs) on feeders. It improved on the efficiency and reduces the cost of circuit breakers required under Current Limiting Reactor implementation in medium and high voltage systems. Two methods were used. One method involved circuit breaker contacts design modification - modifying the straight moving contact to a forked moving contact and the other method - the design of adapters for coupling CLRs and circuit breakers. The results were compared with the result from the existing circuit breaker on Nkalagu-Abakaliki 132kV line, a network in Transmission Company of Nigeria (TCN), and the modified circuit breaker resulted in minimal (negligible) constant power losses in the system, among other benefits. The adapter usage is highly applicable in the Nigerian power system where increasing demand for energy and network expansions lead to short circuit levels of more than the installed capacity of the circuit breakers. The power losses as well as the behavior of the key parameters that determine the operating mechanism energy requirements of circuit breakers during the implementation of the CLRs via the use of adapters or forked moving contacts in circuit breakers were analyzed using MATLAB. The power flow on Nkalagu-Abakaliki 132kV line with the existing circuit breaker and CLR and with the improved circuit breaker and CLR were simulated on POWERWORLD environment. The results obtained showed negligible power loss across the CLR (from 128.11kW to 1.75W and 1.38W for the forked contact and the adapter application respectively) during healthy system condition, nineteen percent reduction in the CB moving contact cross-sectional area (from 9.61 x 10-4m2 to 7.8 x 10-4m2), for a 40kA short-circuit current on a 132kV CB, fifty percent reduction in interrupted fault current (from 40kA to 20kA), sixty-nine percent reduction in the CB cost (from N15,000,000.00 to N4,650,000.00) and seventy-five percent reduction in the heat generated (from 15.52kJ to 3.88kJ), when operating the CB.