Due to a wide range of field vibration problems caused by flood discharge at the Xiangjiaba Hydropower Station, vibration characteristics and influencing factors were investigated based on prototype observation. The r...Due to a wide range of field vibration problems caused by flood discharge at the Xiangjiaba Hydropower Station, vibration characteristics and influencing factors were investigated based on prototype observation. The results indicate that field vibrations caused by flood discharge have distinctive characteristics of constancy, low frequency, small amplitude, and randomness with impact, which significantly differ from the common high-frequency vibration characteristics. Field vibrations have a main frequency of about 0.5-3.0 Hz and the characteristics of long propagation distance and large-scale impact. The vibration of a stilling basin slab runs mainly in the vertical direction. The vibration response of the guide wall perpendicular to the flow is significantly stronger than it is in other directions and decreases linearly downstream along the guide wall. The vibration response of the underground turbine floor is mainly caused by the load of unit operation. Urban environmental vibration has particular distribution characteristics and change patterns, and is greatly affected by discharge, scheduling modes, and geological conditions. Along with the increase of the height of residential buildings, vibration responses show a significant amplification effect. The horizontal and vertical vibrations of the 7th floor are, respectively, about 6 times and 1.5 times stronger than the corresponding vibrations of the 1st floor. The vibration of a large-scale chemical plant presents the combined action of flood discharge and working machines. Meanwhile, it is very difficult to reduce the low-frequency environmental vibrations. Optimization of the discharge scheduling mode is one of the effective measures of reducing the flow impact loads at present. Choosing reasonable dam sites is crucial.展开更多
柔性直流输电系统(high voltage direct current transmission system based on voltage source converter,VSC-HVDC)具有功率独立可控、可向无源负荷供电、能够抑制可再生能源并网发电功率波动等技术优势。该文研制了一套背靠背的VSC-H...柔性直流输电系统(high voltage direct current transmission system based on voltage source converter,VSC-HVDC)具有功率独立可控、可向无源负荷供电、能够抑制可再生能源并网发电功率波动等技术优势。该文研制了一套背靠背的VSC-HVDC实验样机,基于输电系统的工作机理设计了电压源换流器(voltage source converter,VSC)的电气参数及其控制策略,设计了输电系统控制功能协调的系统级控制与功率跟踪的换流器级控制结合的分层控制结构。在并网输电和向无源负荷供电工况下,对样机运行特性进行实验,结果表明,该样机并网输电时具备有功、无功功率独立可控,以及功率反转的能力,同时具有向无源负荷供电功能,且动态性能良好、运行稳定,验证了样机系统设计的正确性。展开更多
In order to study the dynamic response of the unmanned aerial vehicle cabin door opening and closing system under impact load conditions, considering the flexible treatment of mechanical components, and the system’s ...In order to study the dynamic response of the unmanned aerial vehicle cabin door opening and closing system under impact load conditions, considering the flexible treatment of mechanical components, and the system’s motion with different stiffness of energy-absorbing components, a rigid-flexible coupling model of the cabin door actuation system was established in LMS. Virtual. Motion. In Amesim, a control model of the motor was created. Through the Motion-Amesim co-simulation module, the dynamic module of the system was combined with the motor control module to complete the electromechanical coupling simulation and analyze the results. .展开更多
基金supported by the National Natural Science Foundation of China(Grants No.51479124 and 51109143)the Open Cooperation Fund of State Key Laboratory of Hydraulics and Mountain River Engineering(Grant No.SKHL1422)the Nanjing Hydraulic Research Institute Foundation(Grant No.Y115006)
文摘Due to a wide range of field vibration problems caused by flood discharge at the Xiangjiaba Hydropower Station, vibration characteristics and influencing factors were investigated based on prototype observation. The results indicate that field vibrations caused by flood discharge have distinctive characteristics of constancy, low frequency, small amplitude, and randomness with impact, which significantly differ from the common high-frequency vibration characteristics. Field vibrations have a main frequency of about 0.5-3.0 Hz and the characteristics of long propagation distance and large-scale impact. The vibration of a stilling basin slab runs mainly in the vertical direction. The vibration response of the guide wall perpendicular to the flow is significantly stronger than it is in other directions and decreases linearly downstream along the guide wall. The vibration response of the underground turbine floor is mainly caused by the load of unit operation. Urban environmental vibration has particular distribution characteristics and change patterns, and is greatly affected by discharge, scheduling modes, and geological conditions. Along with the increase of the height of residential buildings, vibration responses show a significant amplification effect. The horizontal and vertical vibrations of the 7th floor are, respectively, about 6 times and 1.5 times stronger than the corresponding vibrations of the 1st floor. The vibration of a large-scale chemical plant presents the combined action of flood discharge and working machines. Meanwhile, it is very difficult to reduce the low-frequency environmental vibrations. Optimization of the discharge scheduling mode is one of the effective measures of reducing the flow impact loads at present. Choosing reasonable dam sites is crucial.
文摘柔性直流输电系统(high voltage direct current transmission system based on voltage source converter,VSC-HVDC)具有功率独立可控、可向无源负荷供电、能够抑制可再生能源并网发电功率波动等技术优势。该文研制了一套背靠背的VSC-HVDC实验样机,基于输电系统的工作机理设计了电压源换流器(voltage source converter,VSC)的电气参数及其控制策略,设计了输电系统控制功能协调的系统级控制与功率跟踪的换流器级控制结合的分层控制结构。在并网输电和向无源负荷供电工况下,对样机运行特性进行实验,结果表明,该样机并网输电时具备有功、无功功率独立可控,以及功率反转的能力,同时具有向无源负荷供电功能,且动态性能良好、运行稳定,验证了样机系统设计的正确性。
文摘In order to study the dynamic response of the unmanned aerial vehicle cabin door opening and closing system under impact load conditions, considering the flexible treatment of mechanical components, and the system’s motion with different stiffness of energy-absorbing components, a rigid-flexible coupling model of the cabin door actuation system was established in LMS. Virtual. Motion. In Amesim, a control model of the motor was created. Through the Motion-Amesim co-simulation module, the dynamic module of the system was combined with the motor control module to complete the electromechanical coupling simulation and analyze the results. .
