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Improvement to observability measures of LFO modes in power systems with DFIGs

Shenghu LI

《能源前沿（英文）》 2021年第15卷第2期页码 539-549 doi: 10.1007/s11708-019-0617-z

摘要： Observation of the low-frequency oscillation (LFO) modes in power systems is important to design the damping scheme. The state equations of the power system with the doubly-fed induction generators (DFIGs) are derived to find the LFO modes related to the synchronous generator (SGs) and the DFIGs. The definition of the observability measure is improved to consider the initial output and the attenuation speed of the modes. The sensitivities of the observability measures to the control parameters are derived. The numerical results from the small and large-disturbance validate the LFO modes caused by the DFIGs, and different observability measures are compared. Adjustment of the control parameters is chosen based on the sensitivity model to improve the observability and damping ratio of the LFO mode, and the stability of the wind power system.

关键词： wind power system low-frequency oscillation (LFO) observability measure sensitivity doubly-fed induction generator (DFIG)

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电力系统低频振荡中的非线性奇异现象

马景兰,王伟,万京生,张永丽

《中国工程科学》 2009年第11卷第8期页码 93-96

摘要：

低频振荡是影响电力系统稳定运行的一个重要方面。阐述了低频振荡产生的机理和分析方法，利用Hopf分歧理论，针对一个四阶模型的单机无穷大系统，分析了在临界点附近时可能出现的非线性奇异现象。研究表明：由于分歧的存在，导致系统稳定性在临界点附近出现奇异，从而影响了电力系统的稳定域。

关键词：低频振荡分歧理论非线性奇异

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Improving retrieval precision of NO

Jinpeng YANG

《机械工程前沿（英文）》 2009年第4卷第1期页码 92-96 doi: 10.1007/s11465-009-0001-5

摘要： The NO density error retrieved by the traditional method of differential optical absorption spectroscopy (DOAS) was analyzed. The technique for reducing the error is proposed and used to obtain the NO density of Chengdu through DOAS.

关键词： absorption structure low-frequency structure absorption cross-section NO₂ density

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Oscillation frequency of simplified arterial tubes

Hui AN, Fan HE, Lingxia XING, Xiaoyang LI

《机械工程前沿（英文）》 2009年第4卷第3期页码 300-304 doi: 10.1007/s11465-009-0038-5

摘要： To construct the spatial kinetic equation of an arterial tube and obtain its radial natural frequency, a linear-elastic and small deformation condition is assumed. The theoretical analysis is first presented and the finite element method is then used to numerically simulate the spatial kinematics. The results show that the first-order frequency is 15.8 Hz and the obtained exact analytical solutions agree well with numerical solutions, which proves that the theoretical analysis and numerical simulation are both correct.

关键词： spatial kinematics natural frequency finite element method

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智能电网状态估计中用于提高数据完整性的超分辨率感知技术 Article

梁高琪, 刘国龙, 赵俊华, 刘艳丽, 顾津锦, 孙广中, 董朝阳

《工程（英文）》 2020年第6卷第7期页码 789-800 doi: 10.1016/j.eng.2020.06.006

摘要：

智能电网是一个结合了可再生能源与先进信息和通信技术的国家关键基础设施，为社会提供经济且安全的电力供应。为了应对可再生能源的间歇性特点并确保智能电网的安全性，应该进行更高频率的状态估计运算，而高频率的状态估计运算需要更加完整的系统状态信息。本文从智能电网状态估计数据完整性角度出发，将如何基于低频数据恢复高频数据的问题视为一个超分辨率感知（super resolution perception, SRP）问题。然后提出了一种新颖的基于机器学习的SRP方法，即超分辨率状态估计网络（super resolution perception net for state estimation, SRPNSE）来提高状态估计的数据完整性。此方法主要包含三部分：特征提取、信息补全和数据重建。算例证明了我们提出的SRPNSE方法在状态估计中从低频数据恢复至高频数据的有效性和实用价值。

关键词：状态估计低频数据高频数据超分辨率感知数据完整性

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一种基于数据驱动的浅海低频声源目标位置估计方法 Research Articles

孙显彬1,2,贾鑫明1,郑轶2,王振2

《信息与电子工程前沿（英文）》 2021年第22卷第7期页码 1020-1030 doi: 10.1631/FITEE.2000181

摘要：由于水听器的布置成本高且水下声音传播模型复杂，在浅海环境中进行低频声源目标位置估计较为困难。提出一种基于数据驱动的压缩循环神经网络（compressed recurrent neural network, C-RNN）模型。该模型首先将矢量水听器接收到的声源信号压缩为动态声强信号，然后将声源位置进行GeoHash编码用于该模型的先验训练，最后使用训练好的模型进行浅海低频声源目标的位置估计。与传统数学模型相比，所提C-RNN模型能在复杂声场环境和地形条件下以低参数工况实时估计声源位置。实验结果表明，该模型对浅海环境中低频声源目标位置的平均定位精度为56米。

关键词：矢量水听器；浅海；低频；位置估计；循环神经网络

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含有任意边界的m×n阶RLC网络的等效复阻抗特性 Article

Zhi-zhong TAN, Hong ZHU, Jihad H. ASAD, Chen XU, Hua TANG

《信息与电子工程前沿（英文）》 2017年第18卷第12期页码 2070-2081 doi: 10.1631/FITEE.1700037

摘要：现阶段，精确地计算拓扑网络中任意两节点间等效电阻的技术已经取得较大进展，特别是利用递推-变换（recursion-transform, RT）方法确定含有任意边界的非规则m×n电阻网络的一般等效电阻公式。然而，等效阻抗具有不同于等效电阻的性质，复杂阻抗网络的研究比电阻网络研究困难得多。基于电阻公式，本文研究了含有任意阻抗边界的非规则m×n阶RLC网络的等效复阻抗问题，并发现等效复阻抗的振荡特性和谐振特性。在RLC网络中，当边界阻抗取得一系列特殊值时，复阻抗公式与外部交流电产生共振。结果表明，该公式可以应用到谐振电路中。

关键词： RLC网络；谐振性质；振荡特性；幅频特性

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Frequency domain a9ctive vibration control of a flexible plate based on neural networks

Jinxin LIU, Xuefeng CHEN, Zhengjia HE

《机械工程前沿（英文）》 2013年第8卷第2期页码 109-117 doi: 10.1007/s11465-013-0252-z

摘要：

A neural-network (NN)-based active control system was proposed to reduce the low frequency noise radiation of the simply supported flexible plate. Feedback control system was built, in which neural network controller (NNC) and neural network identifier (NNI) were applied. Multi-frequency control in frequency domain was achieved by simulation through the NN-based control systems. A pre-testing experiment of the control system on a real simply supported plate was conducted. The NN-based control algorithm was shown to perform effectively. These works lay a solid foundation for the active vibration control of mechanical structures.

关键词： active vibration control (AVC) neural network (NN) low frequency noise frequency domain control multi-frequency control

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Comparative study of oscillating flow characteristics of cryocooler regenerator at low temperatures

Yonglin JU , Qingqing SHEN ,

《能源前沿（英文）》 2009年第3卷第1期页码 80-84 doi: 10.1007/s11708-009-0008-y

摘要： A brief review is presented on previous experimental results and correlations on the friction factor of cryocooler regenerators operating at oscillating flow and pulsating pressure conditions, for different mesh sizes of packed woven screens, focusing on the effects of different operating frequencies ranging from 20 to 80 Hz, at room and cryogenic temperatures. A comparison of the friction factor data with those of other studies is presented to clarify the reason for the difference. Finally, a new oscillating flow correlation of regenerators, in terms of several non-dimensional parameters, is discussed and compared.

关键词： friction factor regenerator oscillating flow high frequency

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Analysis and design of pulse frequency modulation dielectric barrier discharge for low power applications

Tang-tang GUO,Xing-liang LIU,Shi-qiang HAO,Chi ZHANG,Xiang-ning HE

《信息与电子工程前沿（英文）》 2015年第16卷第3期页码 249-258 doi: 10.1631/FITEE.1400185

摘要： For low power dielectric barrier discharge (DBD) used in small-size material treatment or portable devices, highstep transformer parasitic capacitance greatly influences the performance of the resonant converter as it is of the same order of magnitude as the equivalent capacitance of DBD load. In this paper, steady-state analysis of the low power DBD is presented, considering the inevitable parasitic capacitance of the high-step transformer. The rectifier-compensated first harmonic approximation (RCFHA) is applied to linearize the equivalent load circuit of DBD at low frequency and the derived expressions are accurate and convenient for the analysis and design of the power supply. Based on the proposed linear equivalent load circuit, the influence of transformer parasitic capacitance on the key parameters, including the frequency range and the applied electrode voltage, is discussed when the power is regulated with pulse frequency modulation (PFM). Also, a design procedure is presented based on the derived expressions. A prototype is constructed according to the design results and the accuracy of the design is verified by experimental results.

关键词： Dielectric barrier discharge Rectifier-compensated first harmonic approximation Parasitic capacitance Power converter design

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Numerical analysis of strongly nonlinear oscillation systems using He’s max-min method

H. BABAZADEH, G. DOMAIRRY, A. BARARI, R. AZAMI, A. G. DAVODI

《机械工程前沿（英文）》 2011年第6卷第4期页码 435-441 doi: 10.1007/s11465-011-0243-x

摘要：

Nonlinear functions are crucial points and terms in engineering problems. Actual and physical problems can be solved by solving and processing such functions. Thus, most scientists and engineers focus on solving these equations. This paper presents a novel method called the max-min method for presenting an accurate approximate analytical solution to strong nonlinear oscillators. It can solve many linear or nonlinear differential equations without the tangible restriction of sensitivity to the degree of the nonlinear term. It is also quite convenient due to the reduction in the size of calculations. The algorithm suggests a promising approach and is systematically illustrated step by step.

关键词： min-max method nonlinear oscillation duffing equation mathematical pendulum He’s energy balance method

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解决未来低惯量电力系统的频率控制难题——英国视角 Perspective

洪启腾, Md Asif Uddin Khan, Callum Henderson, Agustí Egea-Àlvarez, Dimitrios Tzelepis, Campbell Booth

《工程（英文）》 2021年第7卷第8期页码 1057-1063 doi: 10.1016/j.eng.2021.06.005

摘要：

为实现全球艰巨的脱碳目标，电力系统需大规模整合可再生能源发电，这大大降低了系统惯量。除了系统惯量的降低，英国的输电系统还有一些特有的难题：其容量相对较小，同时又与其他输电系统分离，并且可再生资源在整个系统中的分布很大程度上不均匀。本文聚焦英国的输电系统，就低惯量系统中频率控制的相关挑战以及可能的解决方案提出了见解和建议。本文重点讨论了在不同时间尺度上发挥作用的三种主要技术：同步调相机、惯量模拟和快速频率响应。文中借鉴了英国最近的研究和开发项目，评估了其相对优势和局限性及其在解决未来低惯量系统频率控制难题方面的作用。

关键词：快速频率控制惯量模拟同步补偿低惯量系统

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Parametric oscillation of cables and aerodynamic effect

Yong XIA, Jing ZHANG, Youlin XU, Yozo FUJINO,

《结构与土木工程前沿（英文）》 2010年第4卷第3期页码 321-325 doi: 10.1007/s11709-010-0028-z

摘要： This paper addresses the aerodynamic effect on the nonlinear oscillation, particularly parametric vibration of cables in cable-stayed bridges. A simplified 2-DOF model, including a beam and a stayed cable, is formulated first. Response of the cable under global harmonic excitation which is associated with wind speed is obtained using the multiple scales method. Via numerical analysis, the stability condition of the cable in terms of wind speed is derived. The method is applied to a numerical example and a long-span bridge to analyze its all stay cables. It is demonstrated that very large vibration at one of the longest cables in the middle span of the bridge can be parametrically excited when the wind speed is over around 210 km/h (58.5 m/s).

关键词： parametric vibration cables cable-stayed bridge nonlinear vibration