A voltage stability evaluation method for electrical system with load uncertainty

A new voltage stability evaluation method for electricity system associated with load uncertainty is presented. For evaluating the voltage stability, minimal load margin has to be determined under the condition which load of each bus and sum are valued in an interval. In this paper, Low limit of load interval is regarded as current operation point at first, and then get load remnant which is available to dispatch into each bus using bottom boundary of total load subtract from its top boundary. Determine the most dangerous direction through continuous power flow method at current operation point. Then increase load towards this direction as much as possible, the method of boundary fixing is used to amend violating load elements if they exist, iterating repeatedly until finding a set of load distributions, which the distance away from the closest collapse point is shortest. This distance can be regarded as voltage stability evaluation index for electricity system associated with load uncertainty. The simplification and effectiveness of this method are validated on IEEE14-bus and 57-bus System.