• Energy Research

One of the major issues associated with the implementation of direct-current distribution systems is the design of a proper protection scheme. The fault current characteristics in direct-current distribution systems are quite different than those in conventional alternating-current grids. Thus, the performance of conventional protection schemes can adversely be affected, and it is necessary to modify the con-ventional protection schemes or design new protection methods for direct-current networks. This paper proposes a multi-zone differential protection scheme for direct-current distribution systems embedding distributed generators. The proposed method provides a selective and fast protection through the use of a communication link between two sides of a protected feeder. Moreover, the method provides a differential-based backup for the adjacent relays, which can enhance the protection system reliability. In addition, the method proposed in this paper also utilizes directional over-current elements to provide backup protection if the communication network fails. The effectiveness of the proposed protection scheme is evaluated through comprehensive hardware-in-the-loop simulation studies to obtain more realistic results and to investigate the impact of the communication delay. The results show that the proposed method can provide a selective and fast protection and effectively protect components of direct-current distribution systems against different types of faults. Peer Reviewed

©2019 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other uses, in any current or future media, including reprinting/republishing this material for advertising or promotional purposes, creating new collective works, for resale or redistribution to servers or lists, or reuse of any copyrighted component of this work in other works. This paper presents a network clustering (NC) method for active distribution networks (ADNs). Following the outage of a section of an ADN, the method identifies and forms an optimum cluster of microgrids within the section. The optimum cluster is determined from a set of candidate microgrid clusters by estimating the following metrics: total power loss, voltage deviations, and minimum load shedding. To compute these metrics, equivalent circuits of the clusters are estimated using measured data provided by phasor measurement units (PMUs). Hence, the proposed NC method determines the optimum microgrid cluster without requiring information about the network’s topology and its components. The proposed method is tested by simulating a study network in a real-time simulator coupled to physical PMUs and a prototype algorithm implementation, also executing in real time. Peer Reviewed