A DC Optimal Power Flow Model to Improve the Accuracy of DC Power Flow

Application of directed current (DC) power flow model to describe the static security constraints could considerably simplify the complexity of the optimization problems and increase the solving speed and reliability. However, the accuracy of directed current power flow (DCPF) model could not satisfy the accuracy requirement in real applications, especially when the target is large scale power grid. Based on the accurate AC power flow results, a directed current optimal power flow (DCOPF) model is proposed to modify the states of power grid, which aims to reduce the approximation error of DC security constraints comparing with the accurate AC security constraints. The proposed DCOPF model is a linear programming problem in mathematics, which can be solved conveniently and reliably. Using DC security constraints with the modified power system model could generally satisfy the accuracy requirement in optimization applications. The solving difficulties and convergency characters are also significantly better than that of AC power flow method. The proposed method has already applied to some part of southern grid of China.