Estimating restoration duration

Restoration durations are typically estimated based on the availability of various prime mover types, sizes and numbers. In these estimates it is assu med that load can be picked up as soon as generation becomes available, and the time required for switching operation to energize transformers, energi ze lines and pickup loads is much less than the time required to make the g eneration available. In this paper, a case study is presented, supported by a field test, showin g that the above assumptions may not necessarily be correct, and restoratio n duration should be estimated considering both the prime movers timings as well as the switching operations. The paper recommends that the restoration plans should be reviewed and brok en down to its restoration levels, tasks and basic operating actions. Opera ting actions to include: opening/closing breakers, raising/lowering transfo rmer taps, adjusting voltage and frequency set points, starting auxiliary m otors, etc. Then, based on operators' experience, the optimistic time, pess imistic time and the most likely time for each action be estimated and assi gned. The overall restoration duration then can be estimated using the Crit ical Path Method, which in turn may dictate revision of the overall restora tion plan.