Inter-regional transmission line fault often results in power flow transferring, tie-line overloading and system islanding. Traditional control methods such asgenerator tripping and load shedding are costly, and also ...Inter-regional transmission line fault often results in power flow transferring, tie-line overloading and system islanding. Traditional control methods such asgenerator tripping and load shedding are costly, and also have undesirable impacts on theloadside. In this paper, a new emergency power control strategy is proposed for multi-channel interconnected system by using the overload capacity of non-fault DC lines. First of all, the capacity of emergency power control can be acquired by critical transmission power of a certain tie-line for stability. Secondly, the shortest electric distance can be calculated by Dijkstra algorithm, and then the priority of emergency control of the DC lines can be obtained by the entropy weight method. When the inter-regional transmission power decreases and the effect of single DC line emergency control is poor, the multi-channel cooperative emergency control strategy is proposed to ensure the system stability. Simulation results verify the effectiveness of the method proposed.展开更多
We propose and experimentally demonstrate an integrated silicon photonic scheme to generate multi-channel millimeter-wave(MMW) signals for 5 G multi-user applications. The fabricated silicon photonic chip has a footpr...We propose and experimentally demonstrate an integrated silicon photonic scheme to generate multi-channel millimeter-wave(MMW) signals for 5 G multi-user applications. The fabricated silicon photonic chip has a footprint of 1.1 × 2.1 mm^2 and integrates 7 independent channels each having on-chip polarization control and heterodyne mixing functions. 7 channels of4-Gb/s QPSK baseband signals are delivered via a 2-km multi-core fiber(MCF) and coupled into the chip with a local oscillator(LO) light. The polarization state of each signal light is automatically adjusted and aligned with that of the LO light, and then 7 channels of 28-GHz MMW carrying 4-Gb/s QPSK signals are generated by optical heterodyne beating. Automated polarizationcontrol function of each channel is also demonstrated with ～7-ms tuning time and ～27-dB extinction ratio.展开更多
This article investigates the dynamic characteristics of deflectable nose missiles with rotary single-channel control. After introduction of effective attack and sideslip angles as well as quasi-body coordinates based...This article investigates the dynamic characteristics of deflectable nose missiles with rotary single-channel control. After introduction of effective attack and sideslip angles as well as quasi-body coordinates based on the spin characteristics of the missile＇s body, an integrated rigid kinetic model of missile with deflectable nose control is set up in the quasi-body coordinates considering the interaction between the missile＇s nose and body by using rootless multi-rigid-body system dynamics and is linearized. Then an analysis with simulation is conducted to investigate the coupling characteristics between the channels, the influences of nose deflection on the body and the dynamic characteristics of missile＇s body. The results indicate that various channels of missiles with deflectable nose control are coupled cross-linked; the nose deflection tends to make the body move in the opposite direction and, finally, evidences the correctness and reasonability of the kinetic model proposed by this article.展开更多
新能源场站的次/超同步振荡给电力系统的安全稳定运行造成威胁,调相机可以在一定程度上抑制次/超同步振荡。为进一步发挥调相机抑制振荡的能力,提出一种基于储能型双馈调相机的多通道附加阻尼控制策略。首先,设计针对特定频段振荡的附...新能源场站的次/超同步振荡给电力系统的安全稳定运行造成威胁,调相机可以在一定程度上抑制次/超同步振荡。为进一步发挥调相机抑制振荡的能力,提出一种基于储能型双馈调相机的多通道附加阻尼控制策略。首先,设计针对特定频段振荡的附加阻尼控制器,公共耦合点(point of common coupling,PCC)的电流信号经过附加阻尼控制器调制后被输出到机侧控制系统,调节调相机的无功输出实现对系统振荡的有效抑制;其次,根据移相环节的相位补偿偏差将控制器划分为多个通道,每个通道针对特定频段进行振荡抑制;然后,使用Prony算法提取功率振荡信号进行阻尼比计算,评估多通道附加阻尼控制器的振荡抑制效果;最后,在单机系统及新能源场站系统中进行仿真,结果表明多通道附加阻尼控制策略能够显著提高储能型双馈调相机对次/超同步振荡的抑制能力。该策略提高了新能源场站的小干扰稳定性,有利于新能源发电的长期可持续发展。展开更多
文摘Inter-regional transmission line fault often results in power flow transferring, tie-line overloading and system islanding. Traditional control methods such asgenerator tripping and load shedding are costly, and also have undesirable impacts on theloadside. In this paper, a new emergency power control strategy is proposed for multi-channel interconnected system by using the overload capacity of non-fault DC lines. First of all, the capacity of emergency power control can be acquired by critical transmission power of a certain tie-line for stability. Secondly, the shortest electric distance can be calculated by Dijkstra algorithm, and then the priority of emergency control of the DC lines can be obtained by the entropy weight method. When the inter-regional transmission power decreases and the effect of single DC line emergency control is poor, the multi-channel cooperative emergency control strategy is proposed to ensure the system stability. Simulation results verify the effectiveness of the method proposed.
基金supported by the National Key R&D Pro-gram of China under Grant 2016YFB0402501in part by the Natural Science Foundation of China under grant 61605112Open Fund of IPOC under grant BUPT
文摘We propose and experimentally demonstrate an integrated silicon photonic scheme to generate multi-channel millimeter-wave(MMW) signals for 5 G multi-user applications. The fabricated silicon photonic chip has a footprint of 1.1 × 2.1 mm^2 and integrates 7 independent channels each having on-chip polarization control and heterodyne mixing functions. 7 channels of4-Gb/s QPSK baseband signals are delivered via a 2-km multi-core fiber(MCF) and coupled into the chip with a local oscillator(LO) light. The polarization state of each signal light is automatically adjusted and aligned with that of the LO light, and then 7 channels of 28-GHz MMW carrying 4-Gb/s QPSK signals are generated by optical heterodyne beating. Automated polarizationcontrol function of each channel is also demonstrated with ～7-ms tuning time and ～27-dB extinction ratio.
基金Weapons Preliminary Research Key Foundation of China (9140A01010106HK0307)
文摘This article investigates the dynamic characteristics of deflectable nose missiles with rotary single-channel control. After introduction of effective attack and sideslip angles as well as quasi-body coordinates based on the spin characteristics of the missile＇s body, an integrated rigid kinetic model of missile with deflectable nose control is set up in the quasi-body coordinates considering the interaction between the missile＇s nose and body by using rootless multi-rigid-body system dynamics and is linearized. Then an analysis with simulation is conducted to investigate the coupling characteristics between the channels, the influences of nose deflection on the body and the dynamic characteristics of missile＇s body. The results indicate that various channels of missiles with deflectable nose control are coupled cross-linked; the nose deflection tends to make the body move in the opposite direction and, finally, evidences the correctness and reasonability of the kinetic model proposed by this article.
文摘新能源场站的次/超同步振荡给电力系统的安全稳定运行造成威胁,调相机可以在一定程度上抑制次/超同步振荡。为进一步发挥调相机抑制振荡的能力,提出一种基于储能型双馈调相机的多通道附加阻尼控制策略。首先,设计针对特定频段振荡的附加阻尼控制器,公共耦合点(point of common coupling,PCC)的电流信号经过附加阻尼控制器调制后被输出到机侧控制系统,调节调相机的无功输出实现对系统振荡的有效抑制;其次,根据移相环节的相位补偿偏差将控制器划分为多个通道,每个通道针对特定频段进行振荡抑制;然后,使用Prony算法提取功率振荡信号进行阻尼比计算,评估多通道附加阻尼控制器的振荡抑制效果;最后,在单机系统及新能源场站系统中进行仿真,结果表明多通道附加阻尼控制策略能够显著提高储能型双馈调相机对次/超同步振荡的抑制能力。该策略提高了新能源场站的小干扰稳定性,有利于新能源发电的长期可持续发展。
