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
A nonlinear robust trajectory tracking strategy for a gliding hypersonic vehicle with an aileron stuck at an unknown position is presented in this paper. First, the components of translational motion dynamics perpendi...A nonlinear robust trajectory tracking strategy for a gliding hypersonic vehicle with an aileron stuck at an unknown position is presented in this paper. First, the components of translational motion dynamics perpendicular to the velocity are derived, and then a guidance law based on a time-varying sliding mode method is used to realize trajectory tracking. Furthermore, the rotational equations of motion are separated into an actuated subsystem and an unactuated subsystem. And an adaptive time-varying sliding mode attitude controller is proposed based on the actuated subsystem to track the command attitude and the tracking performance and robustness are therefore enhanced. The proposed guidance law and attitude controller make the hypersonic vehicle fly along the reference trajectory even when the aileron is stuck at an unknown angle. Finally, a hypersonic benchmark platform is used to demonstrate the effectiveness of the proposed strategy.展开更多
Time-varying channel modeling plays an important role for many applications in time-variant scenarios,while most clustering algorithms focus on static channels and cannot accurately model the channel time-evolution pr...Time-varying channel modeling plays an important role for many applications in time-variant scenarios,while most clustering algorithms focus on static channels and cannot accurately model the channel time-evolution properties.In this paper,a fuzzy clustering algorithm based on multipath component(MPC)trajectory is proposed.Firstly,both the distance and velocity similarities of the MPCs in different snapshots are taken into account to track the MPC trajectory,in which the fuzzy scheme and a kernel function are used to calculate the distance and velocity similarities,respectively.Secondly,a fuzzy MPC trajectory clustering algorithm is proposed to cluster the MPCs in multiple snapshots.The MPCs in a snapshot are clustered according to the membership,which is defined as the probability that a MPC belongs to different clusters.Finally,time-varying channels at 28 GHz are simulated to validate the performance of our proposed algorithm.The results show that our proposed algorithm is able to accurately identify the clusters in time-varying channels compared with the existing clustering algorithms.展开更多
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.
文摘A nonlinear robust trajectory tracking strategy for a gliding hypersonic vehicle with an aileron stuck at an unknown position is presented in this paper. First, the components of translational motion dynamics perpendicular to the velocity are derived, and then a guidance law based on a time-varying sliding mode method is used to realize trajectory tracking. Furthermore, the rotational equations of motion are separated into an actuated subsystem and an unactuated subsystem. And an adaptive time-varying sliding mode attitude controller is proposed based on the actuated subsystem to track the command attitude and the tracking performance and robustness are therefore enhanced. The proposed guidance law and attitude controller make the hypersonic vehicle fly along the reference trajectory even when the aileron is stuck at an unknown angle. Finally, a hypersonic benchmark platform is used to demonstrate the effectiveness of the proposed strategy.
基金supported by the National Key Laboratory of Electromagnetic Environment(No.202101004)the National Nature Science of China(NSFC)(No.61931001),respectively。
文摘Time-varying channel modeling plays an important role for many applications in time-variant scenarios,while most clustering algorithms focus on static channels and cannot accurately model the channel time-evolution properties.In this paper,a fuzzy clustering algorithm based on multipath component(MPC)trajectory is proposed.Firstly,both the distance and velocity similarities of the MPCs in different snapshots are taken into account to track the MPC trajectory,in which the fuzzy scheme and a kernel function are used to calculate the distance and velocity similarities,respectively.Secondly,a fuzzy MPC trajectory clustering algorithm is proposed to cluster the MPCs in multiple snapshots.The MPCs in a snapshot are clustered according to the membership,which is defined as the probability that a MPC belongs to different clusters.Finally,time-varying channels at 28 GHz are simulated to validate the performance of our proposed algorithm.The results show that our proposed algorithm is able to accurately identify the clusters in time-varying channels compared with the existing clustering algorithms.
