Research On Topology-based Intelligent Recognition Algorithm For Instability Mode Of Large Power Grid

The three-layer security defense system of China’s power grid consists of preventivecontrol, emergency control and restorative control. The setting of preventive control strategyshould base on transient stability assessment. Nowadays the transient stability assessmentworkflow includes procedures stated below: enumerating accidents, solving differentialequations for each accident, observing changes of output variables. Since there are no rules ormodels about the relationship between changes of operation mode and changes of stabilitylevel, power grid operators have to tentatively regulate the arrangement of operation modeover and over relying on their experience and numerous offline simulation results underspecific operation modes. With growth of grid-connection amount of new energy electricityand increase of complexity of grid structure and operation condition, unpredictability of largepower grid is enhancing. It becomes more difficult to guarantee safety in grid operationsimply depending on the operator’s experience.Online and offline stability assessments towards different operation mode are performeddaily by dispatch control center. These results provide huge samples for research in therelationship between operation mode and stability level. Meanwhile, information from widearea measurement system strengthens the observability of grid states. Study of therelationship between operation mode and stability level can start from combination oftransient stability mechanism analysis, data mining technique and pattern recognitiontechnique. Such study will be important application of power grid intelligent dispatch andpower grid big-data mining. Besides, such stud can support intelligent preventive controldecision-making on bulk power systems.The movement of Dominant Instability Generator Group (DIGP) is the main factor oftransient stability level. The paper first proposes a method for recognition of DIGP whichbases on information from operation mode, grid topology and short-circuit voltage at failureoccurrence time. On this basis, an online transient stability assessment algorithm whichmerely adopts steady-state electric variables is presented. The validity of the method is testedon IEEE39-node system and China Southern Grid system.