Complex phenomena such as prolongedly undamped ultra-low frequency oscillation(ULFO)and eigenmode re-excitation are observed in the simulations of hydroelectric power systems.Emphases are put on nonlinearities and mod...Complex phenomena such as prolongedly undamped ultra-low frequency oscillation(ULFO)and eigenmode re-excitation are observed in the simulations of hydroelectric power systems.Emphases are put on nonlinearities and mode interactions,which cannot be analyzed by traditional eigen-analysis methods.In order to investigate the mechanism of the evolvement of the nonlinear dynamic process in ULFO,this paper proposes a method to analyze the mode interactions quantificationally.First,a disturbed trajectory is decoupled into a set of time-varying components.Second,transfer matrices of eigenmodes are extracted along the trajectory.Third,consecutive sequences of eigenvalues and trajectories of components are formed by a proposed technique.Based on the decoupled components and transfer matrices,the mechanisms of mode interactions and inheritance relationships between eigenmodes are analyzed.The causes and developments of the above complex phenomena are revealed by the proposed method in a test two-machine system.Meanwhile,the accuracy of the eigenmode matching technique is verified in the New England system.展开更多
Affected by the nonlinear time-varying factors due to fault scenarios,protection relaying,and control measures,the dynamic behaviors of a power system may be significantly different from the results of previous method...Affected by the nonlinear time-varying factors due to fault scenarios,protection relaying,and control measures,the dynamic behaviors of a power system may be significantly different from the results of previous methods.In order to analyze the oscillation characteristics of complex power systems more accurately and suppress the low frequency oscillation more effectively,this paper improves the trajectory section eigenvalue method.Firstly,the time response of a system is obtained by numerical simulation in a given fault scenario.Secondly,the algebraic variables are substituted to the differential equations along the trajectory.Thus,the original time-varying differential-algebraic equations are approximated by a set of linear ordinary differential equations,which can be updated along the trajectory.On this basis,this paper proposes a method to extract instantaneous features of the oscillation from the micro perspective.The non-equilibrium points with strong nonlinearity or critical eigenmodes are identified by the proposed method.The simulation test results of the IEEE 3-machine 9-bus system and the New England system illustrate the validity of the proposed method.展开更多
基金supported by the Program of State Grid Corporation of China“Theoretical BasisAlgorithmand Application of Trajectory Eigenvalue Method”
文摘Complex phenomena such as prolongedly undamped ultra-low frequency oscillation(ULFO)and eigenmode re-excitation are observed in the simulations of hydroelectric power systems.Emphases are put on nonlinearities and mode interactions,which cannot be analyzed by traditional eigen-analysis methods.In order to investigate the mechanism of the evolvement of the nonlinear dynamic process in ULFO,this paper proposes a method to analyze the mode interactions quantificationally.First,a disturbed trajectory is decoupled into a set of time-varying components.Second,transfer matrices of eigenmodes are extracted along the trajectory.Third,consecutive sequences of eigenvalues and trajectories of components are formed by a proposed technique.Based on the decoupled components and transfer matrices,the mechanisms of mode interactions and inheritance relationships between eigenmodes are analyzed.The causes and developments of the above complex phenomena are revealed by the proposed method in a test two-machine system.Meanwhile,the accuracy of the eigenmode matching technique is verified in the New England system.
基金supported by Science and Technology Program of State Grid Corporation of China(Theoretical Basis,Algorithm and Application of Trajectory Eigenvalue Method).
文摘Affected by the nonlinear time-varying factors due to fault scenarios,protection relaying,and control measures,the dynamic behaviors of a power system may be significantly different from the results of previous methods.In order to analyze the oscillation characteristics of complex power systems more accurately and suppress the low frequency oscillation more effectively,this paper improves the trajectory section eigenvalue method.Firstly,the time response of a system is obtained by numerical simulation in a given fault scenario.Secondly,the algebraic variables are substituted to the differential equations along the trajectory.Thus,the original time-varying differential-algebraic equations are approximated by a set of linear ordinary differential equations,which can be updated along the trajectory.On this basis,this paper proposes a method to extract instantaneous features of the oscillation from the micro perspective.The non-equilibrium points with strong nonlinearity or critical eigenmodes are identified by the proposed method.The simulation test results of the IEEE 3-machine 9-bus system and the New England system illustrate the validity of the proposed method.
