基于物理模型的同步电机参数可辨识性研究

针对实际辨识过程中出现的参数辩识结果不稳定及多解的情况,提出并研究了基于物理模型的同步电机参数的可辨识性.根据模型可辨识性的概念及分析方法,结合三相同步电机的物理模型特点,推导了三相同步电机的观测方程和忽略定子暂态的状态方程,然后基于该状态方程和观测方程,推导了三相同步电机的传递函数矩阵,最后根据可测输入、输出所对应的传递函数,构造了传递函数系数与待辨识参数之间的关系,实现了基于物理模型的三相同步电机参数的可辨识性分析.仿真结果验证了理论分析的正确性,即仅利用暂态和次暂态过程的测量数据就可以辨识三相同步电机的所有电抗参数.     

基于HL7标准的生理参数传输平台设计

提出了一个基于HL7标准的嵌入式生理参数传输平台的设计,然后主要介绍平台的通信层面实现。生理参数采集之后,通过HL7消息的构建与解析实现生理参数在监护终端和医院、社区监护中心之间的数据格式转换,并将HL7消息编码成可扩展标记语言XML进行网络传输;然后介绍了WiFi网络驱动程序的开发过程,通过WLAN无线局域网实现XML数据通信。     

基于参数自适应的直流微源虚拟发电机控制策略

针对分布式电源波动及负载功率突变引起直流微电网母线电压大幅波动的问题,传统虚拟直流电机控制通过模拟直流电机外特性,可抑制母线电压波动,但动态响应较差。对此,提出一种参数自适应的虚拟直流发电机控制策略。以Buck/Boost变换器作为研究对象,结合下垂控制将虚拟直流发电机应用于多变换器并联系统中。建立其小信号模型,分析关键控制参数变化对系统稳定性的影响,并给出惯性系数和阻尼系数自适应调节方程。最后,搭建仿真模型及StarSim HIL实验平台。结果表明所提控制策略在有效抑制直流母线电压波动的同时,使系统具有较快的动态响应速度。     

利用Rabbit2000实现抄表数据在Internet网络的传输

介绍了Rabbit2000微处理器功能特性以及Dynamic C的软件开发环境，研究了基于Rabbit2000的嵌入式系统对网络和串口的编程技术；实现了抄表数据通过Internet网络的传输，介绍了PPP连接的建立以及利用UDP报文传输抄表数据的方法。     

UHVDC系统换相失败故障过程分析及运行参数影响研究

受端交流系统故障是诱发特高压直流系统换相失败的主要原因,严重影响电网安全。为充分明晰交流系统故障下特高压直流系统换相失败期间阀组换相过程和控制响应,通过故障过程的电磁暂态仿真,基于换相面积理论对比阀组实际关断面积和最小关断面积,分析换相失败的主要原因。对运行参数与换相失败和故障恢复的灵敏度展开研究,发现低压限流环节参数和逆变侧控制的比例系数、积分系数对换相失败和故障恢复过程有明显影响,可以在控制系统优化时重点考虑。该研究可为特高压直流换流站换相失败故障分析及稳定运行提供参考。     

通信电缆绝缘单线加工工艺参数的计算

介绍长途对称通信电缆中绝缘单线加工工艺参数的计算。根据长途对称通信电缆工作电容标准值 ,可分别计算出绝缘单线的外径和同轴电容 ,并可计算出挤出机出胶量 ,以及氮气的注入量。另外 ,对挤出温度设置和模具设计等也进行了讨论     

基于乘法器的模拟电路参数测量系统的设计与实现

针对现有模拟电路参数测量方法复杂、测量结果精度低的缺点,构建了基于乘法器的模拟电路参数测量系统。系统中由信号源产生2路正交同频正弦模拟信号,取出一路信号通过待测模拟电路与原信号源产生的2路信号做乘法、滤波处理,产生两路直流信号,之后通过DAQ、LABVIEW采集,得到模拟电路相位差和幅度。经测量,幅度和相位的误差均小于3％,表明该系统具有电路简单、易于实现、误差小、运算速度快等优点,为模拟电路参数测量的研究提出一种可行性方案。     

传动链模型参数对双馈风电机组暂态性能影响

为了较准确地研究并网双馈风电机组机电耦合作用对其暂态性能的影响,考虑风力机和发电机之间传动轴扭转柔性因素,采用等效集中质量法,建立风力机传动链的等效为两个质量块模型.基于并网双馈风力发电机组的功率控制策略和电磁暂态模型,在电网电压跌落故障下,对采用两个等效质量块传动链模型时的机组暂态运行性能进行仿真,并和不考虑传动链柔性的等效为一个质量块模型时的结果进行比较.应用传动链柔性模型,选取不同参数值时的机组暂态效果进行仿真比较和分析.结果表明:考虑风力机传动链柔性有助于准确分析双馈风力发电机组暂态性能,其暂态性能和传动轴系刚度系数、风力机和发电机惯性时间常数密切相关.     

Multiple Gaussian process models for direct time series forecasting

This paper focuses on the problem of time series forecasting using the Gaussian process models. The Gaussian process model is a nonparametric model and the output of the model has Gaussian distribution with mean and variance. The multiple Gaussian process models as every step ahead predictors are used for time series forecasting in accordance with the direct approach. The separable least‐squares approach that combines the genetic algorithm with the linear least‐squares method is applied to train these Gaussian process models. Simulation results are shown to illustrate the effectiveness of the proposed direct forecasting method. © 2011 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

基于ZigBee的电力参数实时监控系统的研究

针对目前国内外电力参数实时监控系统的局限性,提出了一种以ZigBee/IEEE802.15.4无线传感网络和单片机技术为应用平台的电力参数实时监控系统。重点介绍了通过SPI智能终端采集数据,并在ZigBee无线网络中进行数据和信息的无线传输,以实现对电力参数实时监控的方法。     

Enhanced soft-handoff scheme for real-time streaming services in intelligent transportation systems based on CDMA

Code division multiple access (CDMA)-based radio-on-fiber road-vehicle communication systems were proposed to support real-time streaming services in intelligent transportation systems (ITSs). Soft handoff should be provided for real-time streaming services because these services are required to guarantee real-time property and quality of service (QoS). However, soft handoff of real-time streaming services causes the shortage of resource in view of the system. In this paper, the double-adjustment soft-handoff (DASH) scheme is proposed to support seamless service regardless of the shortage of resource and maximize the resource efficiency when real-time streaming services are served in CDMA-based ITSs. The DASH scheme adjusts the data rate of a call when it starts and finishes soft handoff. The performance of the DASH scheme is evaluated by analytical and simulation methods. Performances are evaluated with respect to the blocking probability, the handoff failure probability, and the carried traffic. Numerical results show that the proposed scheme can give relative good maintenance of calls and good throughput.     

Sc filters based on scattering parameters

A systematic method for the simulation of LC ladders and unit-element filters by means of switched capacitor (SC) circuits is proposed. the method is based on the use of wave equivalents of various two-port subnetworks which are now realized by the same type of SC symmetric subcircuits. These subcircuits serve as the structural unit-blocks for realizing high-order circuits. Parasitic-free circuits of practical interest can be developed. Examples of high-order circuits are given. This wave method is simple in its concept and also in the circuit design. Through the alternative solutions which are described, the flexiblity of the method is demonstrated.     

采用脉冲函数建立馈线等效负荷密度模型

提出了以脉冲函数为基的等效负荷密度模型简化配电网分析的方法.针对8种基本负荷分布,求解馈线两端的电压方程和馈线沿线损耗方程,分别获得各种分布的特征值和相似系数,从而不需要量测馈线沿线的各个负荷,也能计算出馈线电压降落和沿线线损.文中给出了若干实例,并与严格计算法、负荷均匀分布法的计算结果进行了比较,结果表明提出的方法是可行的.     

以沃尔什函数为基的馈线等效负荷密度模型

提出了以沃尔什函数为基建立等效负荷密度模型,不需要量测各配电变压器的供出负荷,根据馈线两端的量测数据,确定负荷分布,对配电网进行简化分析计算.文中给出了若干实例,并与严格计算法、负荷均匀分布法的计算结果进行了比较,结果表明了提出的方法是可行的.     

以沃尔什函数为基的馈线等效负荷密度模型

提出了以沃尔什函数为基建立等效负荷密度模型 ,不需要量测各配电变压器的供出负荷 ,根据馈线两端的量测数据 ,确定负荷分布 ,对配电网进行简化分析计算。文中给出了若干实例 ,并与严格计算法、负荷均匀分布法的计算结果进行了比较 ,结果表明了提出的方法是可行的     

采用脉冲函数建立馈线等效负荷密度模型

提出了以脉冲函数为基的等效负荷密度模型简化配电网分析的方法。针对8种基本负荷分布,求解馈线两端的电压方程和馈线沿线损耗方程,分别获得各种分布的特征值和相似系数,从而不需要量测馈线沿线的各个负荷,也能计算出馈线电压降落和沿线线损。文中给出了若干实例,并与严格计算法、负荷均匀分布法的计算结果进行了比较,结果表明提出的方法是可行的     

Computational models for investigation of channel amplifier’s optimal parameters

Microchannel electron multipliers, which amplify the input current of electrons through complicated stochastic processes, have found wide applications in different areas of science and engineering due to a number of remarkable properties. However, the loss of information caused by the statistical fluctuations in the gain of the channels, increases a noise factor which is a measure of the loss of available information. Investigations dealing with reducing of the noise factor are of considerable practical interest. The method, based on 3D Monte Carlo simulations and theorems about serial and parallel amplification stages, is used to show the dependence of the average gain and noise factor on the energy and the incidence angle of the input electron beam, and to find their optimal combination. The spread in incidence coordinates of the electrons of the input beam on the interior surface of a channel is taken into account in the model. The results are compared with a model where the incidence coordinate is same for all input electrons. The numerical experiments show that the spread in the collision coordinates of primary electrons significantly affects the average gain and the noise factor, and must be taken into account in theoretical models. The optimal combinations of the energy and the angle of the input electron beam, which provide the minimal noise factor and maximum gain, are obtained. Such investigations are effectively conducted using the method of serial and parallel amplification stages, and would be practically impossible using only direct simulations by the Monte Carlo methods.     

Performance evaluation of soft handoff for multimedia services in intelligent transportation systems based on CDMA

To support multimedia services in intelligent transportation systems (ITS), CDMA based radio-on-fiber road-vehicle communication systems were proposed. Soft handoff should be provided for multimedia services because these services are required to guarantee real-time property and quality of service (QoS). The performance evaluation of soft handoff is important in view of system management such as determination of optimal resource allocation, cell configuration, and admission strategy. But, the performance evaluation of soft handoff when multimedia services are serviced has not been previously researched, even though there have been some previous works for voice-call service. In this paper, we develop a new analytical model of soft handoff when multimedia services are served in CDMA based ITS. We evaluate the performance of soft handoff scheme by analytical and simulational method. Blocking probability, handoff failure probability and carried traffic are obtained.