An Improved Method for the DCOPF With Losses

This paper discusses the marginal line loss approximation in the dc optimal power flow (DCOPF) and proposes a new methodology that improves the accuracy of current practices. In practice, the DCOPF solution may have significant differences compared to the ac base point that determines marginal losses, and this paper provides the only published example that illustrates this problem to our knowledge. The proposed methodology updates the marginal losses without solving a new ac base point so that the optimal solution accurately reflects system losses. Previously proposed methodologies require nonlinear programming solvers, additional ac power flow solutions, or are less accurate compared to actual losses, and they only give results for one or two test networks. This paper provides results on nine different test networks. The key advantage of the proposed methodology is that it can be easily integrated into current market software.