A New Sequential AC-DC Power Flow Algorithm for Multi-Terminal HVDC Systems

Abstract

This paper presents a new algorithm based on the sequential method for power flow calculation in integrated multi-terminal, high-voltage, direct current (HVDC) systems. Unlike similar studies in the literature, a real equivalent circuit model is considered for under-load tap changer (ULTC) transformers of the DC converters, for the first time. So, new DC equations are obtained. Thus, exact and accurate results can be obtained for practical applications by the proposed algorithm. Adjustment effects of the DC converters' ULTCs tap values are included in the Jacobian matrix instead of the bus admittance matrix in the sequential AC power flow algorithm as well as other ULTCs in AC system. To this aim, new equations for the calculation of power and Jacobian matrix elements are obtained for the AC system. The proposed approach is tested on the modified IEEE 17-bus AC-DC test system. Numerical results show that the proposed approach is accurate and reliable in convergence. (C) 2017 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.