Research On The Analysis Method Of Power System Large Disturbance Dynamic Behavior Based On The Complementary-cluster Intergroup Energy

Power angle oscillation is a common problem in power system operation.The system may occur complex multi-swing low-frequency oscillation under large disturbance,which will harm the operation and stability of the power system.With the construction and operation of the large-scale AC/DC hybrid power grids and the wide application of power electronic equipment in the system,the characteristics of dynamic stability during the low-frequency oscillation process become more and more complex,and the consequences will be more serious.Thus,it is necessary to make further study on the analysis method of power system dynamic stability.Through reflect the effects of time-varying and nonlinear factors in the case of complex models,it can provide fundamental for the dynamic stability control.The nonlinear factors,which caused by complex model and the amplitude limit of controllers,and the time-varying factors,which caused by faults and the behavior of controllers,both will affect the oscillation behavior of power system under lager disturbance.Thus,it is difficult to reflect the variation of power angle during the oscillation process by the linear model at a stationary point.The variation of energy during the oscillation process can not be reflected by energy function defined by the finally structure of the system.Based on the view of the complementary-cluster intergroup energy,which is successful used in power system transient stability quantitative analysis.This dissertation studies the oscillation energy characteristic for the oscillation of complementary-cluster in different time scales.Therefore,the dynamic process of power system oscillation under large disturbance can be reflected in different resolutions.The chief research work of this paper are as follows:1)The rationality of reflecting the influence of nonlinear and time-varying factors from the perspective of energy for the complex dynamic process of the single-machine system oscillation with large disturbance is studied.Through expressing the oscillation energy as a single-valued function of the amplitude,the correspondence between the two and the characteristics of the oscillation energy change with the amplitude are analyzed.Thus,the view of energy and the amplitude both can be used to describe the dynamic stability of H-OMIB system.For the time-varying single-machine system,the relationship between oscillation energy variation and energy loss caused by the time-varying factor is established.Based on this,the rationality of dynamic stability analysis through the view of oscillation energy is studied.2)The feasibility of reflecting the influence of nonlinear and time-varying factors from the perspective of energy for the complex dynamic process of the multi-machine system oscillation with large disturbance is studied.The trajectory of multi-machine system can be mapped into a series of time-varying image system trajectories through the complementary-clusters center-of-inertial relative-motion(CCCOI-RM)transform,and the form unity of image system and time-varying OMIB system is analyzed.Thus,the feasibility of dynamic stability analysis through the view of oscillation energy is proved.3)The method to describe the dynamic behavior of power system based on energy of trajectory swing is presented.Based on the CCCOI-RM transform,the characteristic of energy variation is studied on the two dimensional mode image plane.For the swing identified by the extended equal-area criterion(EEAC),The conversion of kinetic energy and potential energy during the oscillation process is analyzed.Finally,the way to reflect the the macroscopic characteristics of power system oscillation through energy variation of trajectory swing is studied.4)The method to describe the dynamic behavior of power system based on energy of trajectory section is presented.For the image system calculated by CCCOI-RM transform,the souce of time-varying factors and the way by which they affect the oscillation behavior of power system are analyzed.On this basis,the energy of trajectory section is defined by the virtual Hamiltonian system at each section along with the trajectory of the image sysytem,and the way to reflect the local characteristics of power system oscillation through energy variation of trajectory section is studied.