Integration of an Optimal Power Flow Package into the New STEWEAG Energy Management System

Abstract This paper reports on how the special operating problems of the STEWEAG utility have been solved by the implementation of a general purpose Optimal Power Flow (OPF) function in the new Energy Management System (EMS) supplied by ABB. The key operational issues concern the optimal import of energy from the national utility over the various tie lines, and the need to limit parallel power flows through STEWEAG’s network. This is achieved with the help of in-phase and out-of-phase transformers as controls to minimize losses in defined parts of the power system, subject to flow limits on sets of branches (interface constraints). The paper also discusses the problem of integrating third-party application software into the EMS.