Research On Prevention And Control Of Cascading Failure In Power System

With the development of power grid interconnection, not only was great economic benefit achieved, but also power grid was threatened. Some fault in local grid may extend and induce cascading failure. Components quited from grid one after another. This leads to blackouts. So prevention of cascading failures is the key to avoid blackouts.The processes of three blackouts, which are causes by cascading failures are analyzed in the paper. Generic scenario of a cascading blackout is summarizing. By summarizing the course of development of them, evaluative laws and general characteristics of cascading failures are drawn. It is long time between initial fault and trigger fault in typical cascading failure. And it is large intervals among faults in initial phase. The faults in initial phase deteriorate system state and the trigger fault results in cascading failure. Sometimes the faults in cascading phase happened simultaneously. So adjustments must be executed in initial phase to avoid entering into cascading phase.Mechanism of cascading failures is analyzed. In the process of blackout caused by cascading failure, the relation among components is gradually increased, the system enters into self-organized critical state and the system collapses. Based on analysis of evolution law of cascading failure, the paper analyses the mechanism and preventing strategies of cascading failure and puts forward search method of cascading failure by analogy with simple phenomenons.In the paper, a multi-stage sequential-move game model is set up. The model decompose multi-stage into single stage. Each side has one action during single stage: begin with disturbance and end with adjustment. The power grid which has been adjusted can bear next disturbances and it is readjusted after next disturbances. On this basis, the single-stage backwards induction method of solving game model. The process of game is described with game tree. The computation burden is greatly reduced by iterated elimination of weakly actions, and it is well suited for on-line application. The model has good openness, new types of disturbance and new problem can be included in the model.At last, two patterns are put forward to apply the game model to actual power grid. Matching method between two operation mode is brought forth. Based on this method, pattern one comes true.