The optimum power flow (OPF) in an interconnected grid system is an important operation with respect to transmission loss and other operational constraints of the power system. Moreover with the deregulation of the power industry there has been a huge change in the process of operation and control strategies of optimum power flow (OPF). The increase in power transaction with respect to real time increase in demand and for satisfying those demand the competition of the market players (GENCOs), are creating stress on the power system and preventing normal flow of power. Thus leading to power congestion in the system. To allow smooth and quality flow of power the problem of congestion has to be solved. This can be done by rescheduling the generation level of generators at minimum cost and with minimum loss, subjected to load balance. In this work a modified Differential Evolution (DE) algorithm has been utilized to solve the problem of Power Congestion by rescheduling of active power of generators, which are selected on the basis of sensitivity to congested network. It is seen that the proposed method is capable of producing better results.