A review of under-frequency load shedding scheme on TNB system

Safe operation of a power system requires that system frequency be kept within a specified range. When the generation is insufficient due to disturbances, the frequency might fall under the minimum allowable value, which may lead to system blackout if not properly counteracted. This frequency decline may be corrected by shedding certain amount of load so that the system is back into balanced state. This paper reports a case study on Malaysia´s TNB system. UFLS scheme used by TNB was reviewed. Then modification and improvement was made to reflect the current changes in the system making the scheme more up to date. Effect of having more stages to reduce over shedding and combination of different amount of load at each stage are discussed.