A critical path method for the estimation of service restoration time in power distribution systems

Distribution systems (DSs) are invariably subjected to various types of faults, causing power blackouts to occur. Distribution Engineers have the main responsibility to minimizing the duration of these power blackouts. This minimization can be achieved by the detailed study of pre-fault load condition of the DS, isolating the faulted section, and restoring the supply to healthy sections of the DS. Hence the estimation of service restoration time (SRT) is very important in electrical distribution systems (EDS). The estimation of SRT requires detailed knowledge of the commencement time of the emergency diesel generator (EDG) in EDS and also the operating time of the various relays in EDS. This paper introduces a new concept of optimistic time (OT), pessimistic time (PT), and most likely time (MT) of starting of the EDGs in addition to the OT, PT, and MT of the operation of the relays. The proposed concept is tested on 14-bus, 17-bus, and 29-bus distribution networks. The results reveal that it is highly suitable technique for the estimation of SRT under abnormal conditions. Hence this technique can easily be improved in distribution automation/service restoration algorithms. Copyright © 2007 John Wiley & Sons, Ltd.