The presence of distributed generators with DC output power and the advancement in power electronics devices have motivated system planners and grid operators to move towards integration of DC micro grids into conventional AC grid. In this paper, the optimal power flow (OPF) problem in AC-DC networks is addressed. The goal of the AC-DC OPF problem is to jointly minimize the total electricity generation cost of the network and the cost of transferring active power from the AC grid to the DC micro grids. The optimization problem is subject to the power flow constraints, voltage magnitude limits, the limits of the network power lines, and the limits imposed by the power ratings of AC-DC power electronic converters. Since the formulated AC-DC OPF problem is shown to be nonlinear, an approach to reformulate the AC-DC OPF problem as an equivalent traditional AC OPF problem is proposed. Due to the non-convexity of the AC OPF problem, a modified adaptive differential evolution algorithm is proposed. Simulation studies are performed on an IEEE 30-bus system and IEEE 39-bus system connected to 6-bus and 9-bus DC micro grids under both normal operation and network contingency condition. Obtained results from the proposed approach for the test cases confirm the validity of the developed approach.
Volume 10 | 05 - Special Issue
Pages: 1590-1603