Determination of the Load Restoration Sequence Taking into Consideration of the Cost of Power Interruptions ?An investigation of Computing Time of Branch and Bound Method’s Solution -

摘要

When power interruptions happen through fault in a power system, the load should be restored by a sequence which minimizes the cost of power interruptions. Although this problem can be formulated as a linear programing problem based on certain assumptions, it must be formulated as a nonlinear programing problem, if some of these assumptions cannot be held. In latter case, the problem can be effectively solved by the branch and hound method, but, generally, the computing time exceeds the range of practical use. This is a result of the large number of variables. In this problem, it is discovered that the computing time is more than 10 minutes using HITAC/M-180, as the number of variables increases to more than 400. This difficulty can be overcome by introducing a new concept : block priority. Block priority maintains the priority order of one load and the others, as well as minimizing the cost of power interruptions. It allocates simultaneously, the variables of the problem to different levels of priority, giving less than 400 variables to any one priority level, this can reduce the computing time significantly. Nevertheless, it is considered that more work is necessary to develop different effective methods which can further decrease the computing time.