The Research Of Probabilistic Small Signal Stability Based On Cloud Models

With the extended implementation of the strategy of “West to East PowerTransmission, Mutual Supply Between South and North, Nationwide Interconnection” andthe gradually formed interconnection of market-oriented bulk power grids, our powersystems have already entered the generation of large units, extra high voltage, very largescale, long distance, ac-dc hybrid transmission. Nationwide interconnection and high gainexciters can enhance the power system stability, while they can lead to low frequencyoscillation. Regional negative and weak damping can cause the problem of small signalstability, making the interconnection tie oscillated and serious influence on the capacity ofthe transmission line. Analysis of probabilistic small signal stability is of practicalsignificance.Firstly, this article introduces the meaning of power system stability assessment, andpoints out the disadvantage of dealing the problem with uncertainties such as nodal loadand the parameters of operation using deterministic approaches. The results of deterministicapproaches are conservative through the comparison of traditional deterministic analysisand probabilistic stability analysis. The probabilistic method can consider the uncertaintiesconcerning the operational states and provide the useful information for department ofpower dispatch center. So the probabilistic stability assessment has wide application invarious fields. Secondly, a method which combines eigenvalue analysis and Monte Carlosimulation was implemented to the power system evaluation. The probabilistic index andmodels of load and system operational parameters are established, in the meantime aMATLAB based program is developed to analysis the New England system. Thirdly, themethod is based cloud model which have advantage of expressing uncertainties, and themulti-player load model is established using the IEEE-RTS data. Finally, the proposedmulti-layer cloud load model has effective effect on New England System by comparingwith other methods.