The modelling of the distribution transformer winding is the starting point and serves as important basis for the transformer characteristics analysis and the lightning pulse response prediction.A distributed paramete...The modelling of the distribution transformer winding is the starting point and serves as important basis for the transformer characteristics analysis and the lightning pulse response prediction.A distributed parameters model can depict the winding characteristics accurately,but it requires complex calculations.Lumped parameter model requires less calculations,but its applicable frequency range is not wide.This paper studies the amplitude-frequency characteristics of the lightning wave,compares the transformer modelling methods and finally proposes a modified lumped parameter model,based on the above comparison.The proposed model minimizes the errors provoked by the lumped parameter approximation,and the hyperbolic functions of the distributed parameter model.By this modification it becomes possible to accurately describe the winding characteristics and rapidly obtain the node voltage response.The proposed model can provide theoretical and experimental support to lightning protection of the distribution transformer.展开更多
In order to improve the identification capability of ultra wide-band radar,this paper in-troduces a step-variant multiresolution approach for the time-shift parameter estimation. Subsequently,combining with the approa...In order to improve the identification capability of ultra wide-band radar,this paper in-troduces a step-variant multiresolution approach for the time-shift parameter estimation. Subsequently,combining with the approach,a Geometrical Theory of Diffraction(GTD) model-based time-shift Invariant method to target identification using Matching Pursuits and Likelihood Ratio Test(IMPLRT) is developed. Simulation results using measured scattering signatures of two targets in an ultra wide-band chamber are presented contrasting the performance of the IMPLRT to the Wang's MPLRT technique.展开更多
There are some difficulties in using multi-transmission-line (MTL) model for wide band modeling of whole windings of the large power transformer. In this paper, the normalized MTL model is firstly de- rived, with whic...There are some difficulties in using multi-transmission-line (MTL) model for wide band modeling of whole windings of the large power transformer. In this paper, the normalized MTL model is firstly de- rived, with which not only the difficulty of modeling windings with different turn-lengths using MTL can be solved, but also the model can be extended to the modeling of the multi-winding transformer. Secondly, both MTL model and the lumped circuit model on turn basis are mathematically compared in validation of the frequency range and it is pointed out that the lumped circuit model on turn basis is generally valid below 2.5 MHz for EHV and UHV power transformers. Finally, based on the MTL equations, a novel lumped circuit model is derived and it is shown that the valid frequency range of the new circuit is extended to about 4 MHz for modeling large EHV and UHV power transformer windings.展开更多
TDOA(Time Difference of Arrival)测距方式是UWB(Ultra Wide Band)室内定位的常用方法,针对其不可避免的随机误差以及目标改变运动状态定位不准确的问题,文中提出了一种Chan-Taylor-IMMKF(Interacting Multiple Model Kalman Filter)...TDOA(Time Difference of Arrival)测距方式是UWB(Ultra Wide Band)室内定位的常用方法,针对其不可避免的随机误差以及目标改变运动状态定位不准确的问题,文中提出了一种Chan-Taylor-IMMKF(Interacting Multiple Model Kalman Filter)定位算法。该算法由Chan-Taylor加权算法与加入自适应算法IMM卡尔曼滤波算法组成,通过Chan-Taylor加权算法初次取得目标估计坐标,将该坐标值作为自适应算法IMM的卡尔曼滤波器的测量值,对目标坐标进行多次滤波处理,最终加权得到目标的最终估计坐标。实验将该算法与未滤波的Chan-Taylor加权算法、使用传统的卡尔曼滤波算法进行对比,结果显示该算法有效减小了系统的随机误差,并克服了传统卡尔曼滤波器在目标忽然改变运动状态时不能及时跟踪从而产生较大误差的问题,将误差标准差均值控制在15 cm之内。展开更多
高压直流(high voltage DC,HVDC)换流站电磁骚扰主要由阀体内的晶闸管在周期性的导通和关断过程中产生。该骚扰中的高频分量通过辐射和传导2种形式可能会对换流站内的通讯设备、保护与控制系统和载波系统以及换流站附近的无线电台站等...高压直流(high voltage DC,HVDC)换流站电磁骚扰主要由阀体内的晶闸管在周期性的导通和关断过程中产生。该骚扰中的高频分量通过辐射和传导2种形式可能会对换流站内的通讯设备、保护与控制系统和载波系统以及换流站附近的无线电台站等产生影响,所以,建立换流系统的宽频等效电路模型对该骚扰进行计算和预测,研究其时频特性是进行干扰机理分析的前提条件。该文给出了HVDC换流站各主要设备的建模方法及其等效电路,包括阀组件、换流变压器、平波电抗器、滤波器等。其中,阀组件内各元件的阻抗通过网络分析仪测量,然后通过矢量匹配进行零极点提取,最后通过布隆法进行网络综合得到阀组件各器件的宽频等效电路。应用有限元方法计算了阀塔以及散热片的寄生电容参数。以阀塔作为整体,基于PSCAD/EMTDC建立了HVDC换流站换流系统宽频仿真模型。在此基础上,研究了传导电磁骚扰特性。计算结果和测量结果的比较,验证了该文建模方法的正确性。展开更多
基金supported by the National Key Research and Development Plan of China under Grant(2016YFB0900600XXX)
文摘The modelling of the distribution transformer winding is the starting point and serves as important basis for the transformer characteristics analysis and the lightning pulse response prediction.A distributed parameters model can depict the winding characteristics accurately,but it requires complex calculations.Lumped parameter model requires less calculations,but its applicable frequency range is not wide.This paper studies the amplitude-frequency characteristics of the lightning wave,compares the transformer modelling methods and finally proposes a modified lumped parameter model,based on the above comparison.The proposed model minimizes the errors provoked by the lumped parameter approximation,and the hyperbolic functions of the distributed parameter model.By this modification it becomes possible to accurately describe the winding characteristics and rapidly obtain the node voltage response.The proposed model can provide theoretical and experimental support to lightning protection of the distribution transformer.
文摘In order to improve the identification capability of ultra wide-band radar,this paper in-troduces a step-variant multiresolution approach for the time-shift parameter estimation. Subsequently,combining with the approach,a Geometrical Theory of Diffraction(GTD) model-based time-shift Invariant method to target identification using Matching Pursuits and Likelihood Ratio Test(IMPLRT) is developed. Simulation results using measured scattering signatures of two targets in an ultra wide-band chamber are presented contrasting the performance of the IMPLRT to the Wang's MPLRT technique.
文摘There are some difficulties in using multi-transmission-line (MTL) model for wide band modeling of whole windings of the large power transformer. In this paper, the normalized MTL model is firstly de- rived, with which not only the difficulty of modeling windings with different turn-lengths using MTL can be solved, but also the model can be extended to the modeling of the multi-winding transformer. Secondly, both MTL model and the lumped circuit model on turn basis are mathematically compared in validation of the frequency range and it is pointed out that the lumped circuit model on turn basis is generally valid below 2.5 MHz for EHV and UHV power transformers. Finally, based on the MTL equations, a novel lumped circuit model is derived and it is shown that the valid frequency range of the new circuit is extended to about 4 MHz for modeling large EHV and UHV power transformer windings.
文摘高压直流(high voltage DC,HVDC)换流站电磁骚扰主要由阀体内的晶闸管在周期性的导通和关断过程中产生。该骚扰中的高频分量通过辐射和传导2种形式可能会对换流站内的通讯设备、保护与控制系统和载波系统以及换流站附近的无线电台站等产生影响,所以,建立换流系统的宽频等效电路模型对该骚扰进行计算和预测,研究其时频特性是进行干扰机理分析的前提条件。该文给出了HVDC换流站各主要设备的建模方法及其等效电路,包括阀组件、换流变压器、平波电抗器、滤波器等。其中,阀组件内各元件的阻抗通过网络分析仪测量,然后通过矢量匹配进行零极点提取,最后通过布隆法进行网络综合得到阀组件各器件的宽频等效电路。应用有限元方法计算了阀塔以及散热片的寄生电容参数。以阀塔作为整体,基于PSCAD/EMTDC建立了HVDC换流站换流系统宽频仿真模型。在此基础上,研究了传导电磁骚扰特性。计算结果和测量结果的比较,验证了该文建模方法的正确性。
