In a market environment

transmission congestion (TC) poses a threat to the system security and facilitates market power abuse. Interruptible load (IL) can be viewed as a power resource

and the TC problem could be relieved using this source. An IL based TC management model is proposed

in which customers can bid their IL quantities and prices to the wholesale market. This model consists of a two-level optimization model. The outer optimal power flow (OPF) model is to determine nodal prices and dispatch power generation. The inner optimal model is to determine appropriate ILs to relieve the TC. To solve the nonlinear complementarity problems (NCP) in the model solution

NCP functions are used to reformulate NCPs as a set of nonlinear algebraic equations

and then an inexact Levenberg-Marquardt algorithm is employed to solve all the equations. A modified IEEE 30-bus system is used to illustrate the validity of the proposed model.