Pricing of System Security with Voltage Stability Constraint

Deregulation of electric power industry has affected its overall operation, which in turn has altered the pricing strategy. In this paper, we present a suitable pricing system for this emerging environment. The proposed multi-objective OPF gives optimum pricing while incorporating voltage stability, security and reliability constraints. Voltage stability constraint is included to ensure the stability of the system by maintaining a minimum distance of the operating point from the voltage collapse point. Security and reliability constraints are added to the pricing mechanism as cross-subsidy for these services is not allowed in this environment, unlike the monopolistic structure. The effect of contingency and congestion on pricing is also analyzed. The congestion is estimated from the available transfer capability, which is calculated by repeated power flow considering bus voltage and line thermal limit. Finally, the model is tested on IEEE 14-bus and 30-bus systems and also on the North-Eastern India grid.