SECURITY-CONSTRAINED OPF - INFLUENCE OF FIXED TAP TRANSFORMER FED LOADS

An earlier study considered the behavior of conventional OPF solutions (neglecting contingencies) in the presence of loads not controlled by ULTC transformers. In the present paper, the behavior of the conventi onal security-constrained OPF solutions is studied under similar condi tions. Modified versions of the AEP/IEEE 30 bus system with exponentia l type load models are used to create a variety of test situations. Th e present study reveals that with loads not controlled by ULTC transfo rmers, the solution to a conventional security-constrained OPF can be different from its practically observed version. This conclusion is si milar to that obtained for OPF neglecting contingencies. In the presen t case, since the voltages are usually higher than for OPF neglecting contingencies, it follows that an increase in fuel costs, power demand , total and net revenue can be expected in more cases than in the prev ious study. Moreover, unlike the previous study, limit violations in t he present case are observed mainly during contingencies.