LMP calculation and OPF based congestion management in deregulated power systems

Abstract

In restructured electricity markets, an effective transmission pricing method is required to address transmission issues and to generate correct economic signals. Transmission line constraints can result in variations in energy prices throughout the network. These prices depend on generator bids, load levels, and transmission network limitations. A congestion charge is incurred when the system is constrained by physical limits. Locational marginal pricing (LMP) has become a popular method in restructured power markets to address the congestion price. This paper presents, LMP calculations at each bus when system working under normal and congested condition, and the congested system has been relieved by optimal placement of TCSC and DG unit. The optimal placement of TCSC and DG unit are suggested by real power flow and transmission line relief (TLR) sensitivity indexes. Optimal power flow based congestion management (OPF based CM) problem is employed to minimize the cost, calculate LMP's and relieve network congestion in the systems. Were the OPF based CM problem solutions have been obtained by Primal Linear Programming (PLP) and Genetic Algorithm (GA), the developed models have been applied for 26 bus power system network. The comparison is made between PLP and GA OPF CM problem solutions, where the solution by the GA method gave better economic results.