Congestion Management in Hybrid Electricity Market for Hydro - Thermal System

The power system restructuring has introduced competitiveness among different market players in electricity market and as a result transmission lines have to operate near to their thermal limits. System operators have a challenge to ensure reliable and secure transmission of power under these conditions. In this paper a rescheduling based congestion management solution is proposed for hybrid electricity market containing hydro-thermal units. The objective of the problem is to minimize the congestion management cost by suitably rescheduling the generation of hydro and thermal units based on their up and down generation cost bids. The hydro units having the least cost and fast start up time have been used to alleviate the congestion by considering the non-concave piecewise linear performance curves for them. The bilateral transactions between different entities have also been considered while rescheduling of the generators for congestion management. The proposed model has been tested on modified IEEE-24 bus system. It can be observed that presence of hydro units reduces the overall congestion management cost and reactive power requirement.