Effect of congestion and voltage security on pricing in deregulated environment

Deregulation of electric industry has a direct impact on the increasing number of transactions. This lowers the available margin and leads to the increased congestion of transmission lines. Thus the system becomes more vulnerable to collapse. Analyzing the system security and congestion, and determining their effects on pricing becomes more important than ever in the deregulated environment. This paper studies the effect of congestion and voltage stability constraint (VSC) on pricing and that is applied on the 132 KV part of the North-Eastern Grid of India for practical reliability analysis of the proposed model. Locational marginal price (LMP) is used to study the effect of congestion in the pricing model. The VSC is included in the optimal power flow (OPF) problem that maximizes the social benefit and the distance from the nose point. Other security constraints like voltage limits and reactive power limits are also included in OPF. Available transfer capability (ATC) is evaluated using repeated power flow. The concept of loadability is used to include voltage stability constraint in OPF. Linear programming technique is used here to solve the OPF problem. The effect of N-1 contingency is also considered on congestion. N-1 contingency is incorporated by considering generator loss and line loss (one by one). Loss of heavily loaded lines is considered for this model. The model is tested on the 80 bus, 132 kV system of the North-Eastern Grid of India and implemented on Matlab environment.