Research Of Dynamic Equivalent Of Power Machine Based On Sensitivity Analysis

With the pace of hydropower development in C hina accelerated,more and more hydeopower units has been built.Their impact can not be ignored.Due to the large number,widely distributing,complex network structure of the units, there is an urgent need to the dynamic equivalence of hydeopower units,to carry on the analysis of the power system in the simulation on the grid.At present,the analysis method of dynamic equivalence is mainly composed of coherency method and parameter identification method.Coherency method requires all the parameters in external system.It has strong theoretical basis and long-time application in engineering, with rich theoretical basis and practical experience. With the increasing scale and structure complexity of power system in recent years,online equivalent has been put forward,which coherency method cannot complete.So t he parameter identification method is more and more popular in the application of dynamic equivalent due to its real time.In addition,the sensitivity of parameters is widely used in dynamic equivalence,It's of great help to the dynamic characteristic analysis of power system.Firstly this paper introduces the coherency method and make detailed study of the specific methods and steps.Then we make an equivalent calculation of the concrete example and get the ideal equivalent results.Secondly,in this paper, the parameters identification method is introduced.The equivalent value model and intelligent optimization algorithm is described in detail.Then trajectory sensitivity, eigenvalue sensitivity are researched in detail.Starting from the perspective of parameter sensitivity,parameter identifiability is analysed,which provides another way of the analysis of the parameter identifiability.Combine coherency method and parameter identification method, the dynamic equivalent improvement method based on sensitivity analysis is put forward. The degree of difficulty of the parameter identification is judged from the sensitivity analysis to distinguish the unknown parameters. Sensitive parameters are identified by parameter identification,while the insensitive ones are got from the results of coherent equivalent.Finally,the feasibility and validity of the method is verified by simulation in the actual example.