A Solution Method Of Dynamic Security Region Of Power System Based On Critical Instability Modes

With the socio-economic rapid development,the level of interconnection of power system is improving,the complexity and diversity of the power system scale is rising,if a fault occurs suddenly in power system and operators don't implement timely effective measures,it is likely to be in a state of transient instability for power system,and in severe cases the system will be in a state of disruption which will lead to large-scale power blackout and catastrophic consequences,therefore dynamic security analysis of power system is very important for safe and stable operation of the power system,method of domain of the power system can provide more extensive information about security,and it has great prospects.The method about domain proposed is dynamic security region of power system,there are many ways to calculate dynamic security region of power system,but it is a problem to calculate dynamic security region of power system quickly and accurately.The structure of the power network is more complex and large scale,when a fault occurs in power system,the dynamic response of the system may show a more diverse pattern of instability modes,it is very important significance to identify instability modes for making effective measures which make the system operate stably and safely.This paper presents a new method of identifying instability modes.It is based on initial acceleration of the generator and takes discrete Fréchet distance as means of the analysis of similarity of swing curve of the generator to identify instability modes.New England 10-machine 39-bus system is verification and the results are verified by the swing curve of the generator,we found that the method is reasonable and feasible,the calculation is simple,identification is rapid.Border nature is that dynamic security domains of the power system consists of hyperplane which is calculated by various instability modes about the given system under the conditions of given fault and parameters.and thus,this paper proposes a method of dynamic security domain based on the critical instability modes,it is first step to search the critical point of the system by the quasi-orthogonal method,and then it needs to identify theinstability modes of critical point,and then it needs to compute hyperplanes of the same instability modes by the differential methods according to the number of critical generator,If the critical generator set of instability modes only has one generator,we choose improved analytical method as the method of computing hyperplanes.Otherwise,we choose fitting method as the method of computing hyperplanes,At this time,we only chose the generator of the critical generator set as critical node to make of dimension reduce.finally each hyperplane of the same instability modes constitutes border of the dynamic security domains.Case studies on New England10-machine 39-bus system shows that the speed of calculation is quick and the accuracy is quite credible.