Contingency-constrained congestion management with a minimum number of adjustments in preferred schedules

Transmission network plays a major role in the open access deregulated power market. In this environment, transmission congestion is a major problem that requires further consideration especially when inter-zonal/intra-zonal scheme is implemented. A congestion problem formulation should take into consideration interactions between intra-zonal and inter-zonal hows and their effects on power systems. It is perceived that phase-shifters and tap transformers play vital preventive and corrective roles in congestion management. These control devices help the ISO mitigate congestion without re-dispatching generation away from preferred schedules. In this paper, we introduce a procedure for minimizing the number of adjustments of preferred schedules to alleviate congestion and apply control schemes to minimize interactions between zones while taking contingency-constrained limits into consideration. The paper shows the stage where the ISO performs contingency analysis during congestion management, and shows the effect of contingency limits on congestion management. The proposed formulation will save computation time, increase the system security and apply control variables efficiently in the transmission system management to keep power system operation close to preferred schedules. (C) 2000 Elsevier Science Ltd. Ail rights reserved.