Modification of DC Optimal Power Flow, Based on Nodal Approximation of Transmission Losses

The Optimal Power Flow is one of the fundamental problems in power system analyses. Some essential studies in power system operation and planning typically require a large number of repetitive OPF solutions. In these analyses, the convergence speed of the OPF solutions beside their accuracy are two key objects. The full ACOPF is accurate, but takes long solution time. The DCOPF is a simple approximation of OPF that is very fast but is not so accurate. This paper presents a method to improve the accuracy of DCOPF, based on evaluating some nodal shares of transmission losses. Like the previous DCOPF, the Modified DCOPF is derived from a non-iterative DC power flow, and thus its solution requires no long run time. Moreover, it can simply be realized in the form of Lagrange representation, makes it possible to be considered as some constraints in the body of any bi- level optimization problem, with its internal level including the OPF satisfaction. The efficiency of the Modified DCOPF is illustrated through implementing on three test cases (IEEE 30 118 Bus test systems and Iran 2006 Transmission Network) and comparing the results (generation levels, line flows, and voltage angles) with the conventional DCOPF and full ACOPF.