The aim of this paper is to establish a general decay result for a one-dimensional porous elastic system with different speeds of wave propagation in the presence of macrotem- perature effect and visco-porous dissipat...The aim of this paper is to establish a general decay result for a one-dimensional porous elastic system with different speeds of wave propagation in the presence of macrotem- perature effect and visco-porous dissipation.展开更多
A new variable speed control moment gyro(VSCMG) steering law is proposed in order to achieve higher torque precision. The dynamics of VSCMGs is established, and two work modes are then designed according to command to...A new variable speed control moment gyro(VSCMG) steering law is proposed in order to achieve higher torque precision. The dynamics of VSCMGs is established, and two work modes are then designed according to command torque: control momentum gyro(CMG)/reaction wheel(RW) hybrid mode for the large torque case and RW single mode for the small. When working in the CMG/RW hybrid mode, the steering law deals with the gimbal dead-zone nonlinearity through compensation by RW sub-mode. This is in contrast to the conventional CMG singularity avoidance and wheel speed equalization, as well as the proof of definitely hyperbolic singular property of the CMG sub-mode. When working in the RW single mode, the motion of gimbals will be locked. Both the transition from CMG/RW hybrid mode to RW single mode and the reverse are studied. During the transition, wheel speed equalization and singularity avoidance of both the CMG and RW submodes are considered. A steering law for the RWs with locked gimbals is presented. It is shown by simulations that the VSCMGs with this new steering law could reach a better torque precision than the normal CMGs in the case of both large and small torques.展开更多
Droop control has been widely used for controlling distributed generators.As capacity of the MMC inverter may be insufficient,a power allocation method for grid-connected MMC inverter based on droop control is present...Droop control has been widely used for controlling distributed generators.As capacity of the MMC inverter may be insufficient,a power allocation method for grid-connected MMC inverter based on droop control is presented to improve the stability of the power system.As there is potential for large disturbances in the power grid,an equal speed regulation strategy is adopted to make the speed of the voltage collapse be the same as the frequency collapse.With obtaining the active and reactive power references of MMC inverter according to equal speed regulation strategy,the deadbeat control method is calculated using these power references and adopted to track the reference currents.The Routh criterion is used to analyze the influence of the inductance measurement error on the control system.Additionally,a simulation model is established with Matlab and Simulink.The simulation results show that the stability of the power grid has been improved with the proposed control method.展开更多
文摘The aim of this paper is to establish a general decay result for a one-dimensional porous elastic system with different speeds of wave propagation in the presence of macrotem- perature effect and visco-porous dissipation.
基金supported by the National Natural Science Foundation of China (No. 11272027)
文摘A new variable speed control moment gyro(VSCMG) steering law is proposed in order to achieve higher torque precision. The dynamics of VSCMGs is established, and two work modes are then designed according to command torque: control momentum gyro(CMG)/reaction wheel(RW) hybrid mode for the large torque case and RW single mode for the small. When working in the CMG/RW hybrid mode, the steering law deals with the gimbal dead-zone nonlinearity through compensation by RW sub-mode. This is in contrast to the conventional CMG singularity avoidance and wheel speed equalization, as well as the proof of definitely hyperbolic singular property of the CMG sub-mode. When working in the RW single mode, the motion of gimbals will be locked. Both the transition from CMG/RW hybrid mode to RW single mode and the reverse are studied. During the transition, wheel speed equalization and singularity avoidance of both the CMG and RW submodes are considered. A steering law for the RWs with locked gimbals is presented. It is shown by simulations that the VSCMGs with this new steering law could reach a better torque precision than the normal CMGs in the case of both large and small torques.
基金by the National Key Research and Development Plan of China under Grant 2016YFB0901001。
文摘Droop control has been widely used for controlling distributed generators.As capacity of the MMC inverter may be insufficient,a power allocation method for grid-connected MMC inverter based on droop control is presented to improve the stability of the power system.As there is potential for large disturbances in the power grid,an equal speed regulation strategy is adopted to make the speed of the voltage collapse be the same as the frequency collapse.With obtaining the active and reactive power references of MMC inverter according to equal speed regulation strategy,the deadbeat control method is calculated using these power references and adopted to track the reference currents.The Routh criterion is used to analyze the influence of the inductance measurement error on the control system.Additionally,a simulation model is established with Matlab and Simulink.The simulation results show that the stability of the power grid has been improved with the proposed control method.
