Redesign of frequency controls for CPS evaluations in an isolated power system

Since North American Electric Reliability Council (NERC) issued the new control performance standard (CPS) in 1997, this standard has become the major paradigm of operating principle for load frequency control among the interconnection systems in North America. Based on the interconnected structure, NERC´s CPS is to define the permissible distribution of areas´ frequency deviations, and to limit areas´ unscheduled tie-flows within an interconnection. As far as the whole power system is concerned, CPS is meant to monitor long-term performance of frequency controls. It naturally allows short term control relaxation from the control point of view. Accordingly, two operational concepts are proposed in this paper to achieve the objectives of both unit maneuvering relaxation and CPS quality. Using multi-objective optimization algorithm, the proposed concepts are successfully implemented and verified in the simulation cases.