A novel slack bus-free load flow method for dc microgrids and distribution systems with dc-bus signaling control methods

A significant section of the future electrical power systems, that is, smart grids, will be dc microgrids and distribution systems. Obviously, the voltage control is one of the important issues of these dc power systems. DC-bus signaling (DBS) control methods, as distributed, autonomous, simple, highly reliable, inexpensive, modular and practical control methods, are one of the most important categories of the voltage control methods in dc microgrids and distribution systems. In the dc power systems with DBS control methods, the determination of the generated power shares of the distributed power sources, as vital entries for the conventional load flow methods, before the execution of a load flow method, is not possible. Also, in these dc power systems, none of the power sources can be considered as a constant voltage source, that is, the slack source. Consequently, the conventional load flow methods are not applicable to dc microgrids and distribution systems with DBS control methods. In this paper, a novel, practical, robust, fast, precise load flow method is presented to overcome the mentioned serious complexities in the dc power systems. The proposed load flow method necessitates the least input data. It determines the generated power shares of all the sources during its execution. Besides, the load flow method necessitates no constant voltage source or slack source. Furthermore, the proposed load flow method benefits from low computational time and the storage requirements and the removal of the ill-conditioned problem. The algorithm validation and the numerical results derived in this paper confirm the accuracy and the remarkable performance of the load flow method. Copyright (C) 2015 John Wiley & Sons, Ltd.