Power quality detecting based on fast lifting wavelet transform
电压闪变与波动的外文翻译
Measurement of a power system nominal voltage, frequency and voltage flicker parametersA.M. Alkandari a, S.A. Soliman b,*a b s t r a c t:We present, in this paper, an approach for identifying the frequency and amplitude of voltage flicker signal that imposed on the nominal voltage signal, as well as the amplitude and frequency of the nominal signal itself. The proposed algorithm performs the estimation in two steps; in the first step the original voltage signal is shifted forward and backward by an integer number of sample, one sample in this paper.The new generated signals from such a shift together with the original one is used to estimate the amplitude of the original signal voltage that composed of the nominal voltage and flicker voltage. The average of this amplitude gives the amplitude of the nominal voltage; this amplitude is subtracted from the original identified signal amplitude to obtain the samples of the flicker voltage. In the second step, the argument of the signal is calculated by simply dividing the magnitude of signal sample with the estimated amplitude in the first step. Calculating the arccosine of the argument, the frequency of the nominal signal as well as the phase angle can be computing using the least error square estimation algorithm. Simulation examples are given within the text to show the features of the proposed approach.Keywords: Power quality Nominal frequency and amplitude measurements Voltage flicker Frequency and amplitude estimation Forward and backward difference1.IntroductionV oltage flicker and harmonics are introduced to power system as a result of arc furnace operation, and power utilities are concern about their effects. As such an accurate model for the voltage flicker is needed. The definition of voltage flicker in IEEE standards is the ‘‘impression of fluctuating brightness or color, when the frequency observed variation lies between a few hertz and the fusion frequency of image” [1]. The flicker phenomenon may be divided into two general categories, cyclic flicker and non-cyclic flicker. Cyclic flicker is repetitive one and is caused by periodic voltage fluctuations due to the operation of loads such as spot welders, compressors, or arc welders. Non-cyclic flicker corresponds to occasional voltage fluctuations, such as starting of large motors, some of loads will cause both cyclic andnon-cyclic flicker, such as arc furnace, welder, and ac choppers.Over the past three decades, many digital algorithms have been developed and tested to measure power system frequency and rate of change of frequency. Ref. [2] presents the application of the continuous Wavelet transform for power quality analysis. The transform appears to be reliable for detecting and measuring voltage sags, flicker and transients in power quality analysis. Ref. [3] pays attention to the fast Fourier transform and its pitfalls. A low pass.digital filter is used, and the effects of system voltage deviation on the voltage - flicker measurements by direct FFT are studied. The DC component leakage effect on the flicker components in the spectrum analysis of the effective value of the voltage and the windowing effect on the data acquisition of the voltage signal are discussed as well.A digital flicker meter is proposed in Ref. [6] based on forward and inverse FFT and on filtering, in the frequency domain, for the implementation of the functional blocks of simulation of lamp–eye–brain response. Refs. [5–7] propose a method based on Kalman filtering algorithms to measure the low frequency modulation of the 50/60 Hz signal. The method used, in these references, allows for random and deterministic variation of the modulation. The approach utilizes a combination of linear and non-linear Kalman filter modes.Ref. [8] presents a method for direct calculation of flicker level from digital measurements of voltage waveforms. The direct digital implementation uses Fast Fourier transform (FFT) as the first step in computation. A pruned FFT, customized for the flicker level computation, is also proposed. Presented in Ref. [9] is a static state estimation algorithm based on least absolute value error (LA V) for measurement of voltage flicker level. The waveform for the voltage signal is assumed to have, for simplicity, one flicker component. This algorithm estimates accurately the nominal voltage waveform and the voltage flicker component. An application of continuous wavelet transform (CWT) for analysis of voltage flicker-generated signals is proposed in Ref. [10] With the time-frequency localization characteristics embedded in the wavelets, the time and frequency information of a waveform can be integrally presentedRef. [11] presents an arc furnace model that implemented in the Simulink environment by using chaotic and deterministic elements. This model is obtained by solving the corresponding differential equation, which yields dynamic and multivalued v i characteristics of the arc furnace load. In order to evaluate the flicker in the simulated arc furnace voltage, the IEC flicker meter is implemented based on the IEC 1000-4-15 standard in Matlab environment.Ref. [12] presents an approach to estimate voltage flicker components magnitudes and frequencies, based on Lp norms (p = 1,2 and 1) and Taylor’s’ series linearization. It has been found that it is possible to design an Lp estimator to identify flicker frequency and amplitude from time series measurements. The Teager energy operator (TEO) and the Hilbert transform (HT) are introduced in Ref. [13] as effective approaches for tracking the voltage flicker levels. It has been found that TEO and HT are capable of tracking the amplitude variations of the voltage flicker and supply frequency in industrial systems with an average error 3%.Ref. [14] presents a control technique for flicker mitigation. This technique is based on the instantaneous tracking of the measured voltage envelope. The ADALINE (ADAptive LINear) neuron algorithm and the Recursive Least Square (RLS) algorithm are introduced for the flicker envelope tracking. In Ref. [15], an algorithm for tracking the voltage envelope based on calculating the energy operator of a sinusoidal waveform is presented. It is assumed that the frequency of the sinusoidal waveform is known and a lead-lag network with unity gain is used. Ref. [16] develops an enhanced method for estimating the voltage fluctuation (DV10) of the electric arc furnace (EAF). The method proposed considers the reactive power variation and also the active power variation in calculating DV10 value of ac and dc LEAFsControl and protection of power systems requires accurate measurement of system frequency. A system operates at nominal frequency, 50/60 Hz means a balance in the active power, i.e. The power generated equals the demand power plus losses. Imbalance in the active power causes the frequency to change. A frequency less than the nominal frequency means that the demand load plus losses are greater than the power generated, but a frequency greater than nominal frequency means that the system generation is greater than the load demand plus losses. As such, frequency can be used as a measure of system power balance.Ref. [17] presents a numerical differentiation-based algorithm for high-accuracy, wide-range frequency estimation of power systems. The signal, using this algorithm, includes up to 31st-order harmonic components. Ref. [18] presents a method for estimation of power frequency and its rate of change. The proposed methodaccommodates the inherent non-linearity of the frequency estimation problem. The estimator is based on a quadrature phase-look loop concept.An approach for designing a digital algorithm for local system frequency estimation is presented in Ref. [19]. The algorithm is derived using the maximum likelihood method. A recursive Newtontype algorithm suitable for various measurement applications in power system is developed in Ref. [20] and is used for power system frequency and spectra estimation. A precise digital algorithm based on discrete Fourier transforms (DFT) to estimate the frequency of a sinusoid with harmonics in real-time is proposed in Ref. [21]. This algorithm is called smart discrete Fourier transform (SDFT) that avoids the errors due to frequency deviation and keeps all the advantages of the DFT.Ref. [22] presents an algorithm for frequency estimation from distorted signals. The proposed algorithm is based on the extended complex Kalman filter, which uses discrete values of a three-phase voltage that are transformed into the well-known ab-transform Using such a transformation a non-linear state space formulation is obtained for the extended Kalman filter. This algorithm is iterative and complex and needs much computing time and uses the three-phase voltage measurements, to calculate the power system voltage frequency.Ref. [23] describes design, computational aspect, and implementation aspects of a digital signal processing technique for measuring the operating frequency of a power system. It is suggested this technique produces correct and noise-free estimates for near nominal, nominal and off-nominal frequencies in about 25 ms, and it requires modest computation. The proposed technique uses per-phase digitized voltage samples and applies orthogonal FIR digital filters with the least errors square (LES) algorithm to extract the system frequency.Ref. [24] presents an iterative technique for measuring power system frequency to a resolution of 0.01–0.02 Hz for near nominal, nominal and off-nominal frequencies in about 20 ms. The algorithm in this reference uses per-phase digitized voltage samples together with a FIR filter and the LES algorithm to extract iteratively the signal frequency.This algorithm has beneficial features including fixed sampling rate, fixed data window size and easy implementationRefs. [25,26] present a new pair of orthogonal filters for phasor computation; the technique proposed extracts accurately the fundamental component of fault voltageand current signal. Ref. [27] describes an algorithm for power system frequency estimation. The algorithm, applies orthogonal signal component obtained with use of two orthogonal FIR filters. The essential property of the algorithm proposed is outstanding immunity to both signals orthogonal component magnitudes and FIR filter gain variations. Again this algorithm uses the per-phase digitized voltage samples.Ref. [28] presents a method of measuring the power system frequency, based on digital filtering and Prony’s estimation. The discrete Fourier transform with a variable data window is used to filter out the noise and harmonics associated with the signal. The results obtained using this algorithm are more accurate than when applying the method based on the measurement of angular velocity of the rotating voltage phasor. The response time of the proposed method equals to three to four periods of the fundamental components. This method uses also per phase digitized voltage samples to compute the system frequency from harmonics polluted voltage signal. Ref. [29] implements a digital technique for the evaluation of power system frequency. The algorithm is suitable for microprocessor implementation and uses only standard hardware. The algorithm works with any relative phase of the input signal and produces a new frequency estimate for every new input sample. This algorithm uses the orthogonal sine and cosine- filtering algorithm..A frequency relay, which is capable of under/over frequency and rate of change of frequency measurements using an instantaneous frequency-measuring algorithm, is presented in Ref. [30]. It has been shown that filtering the relay input signal could adversely affect the dynamic frequency evaluation response. Misleading frequency behavior is observed in this method, and an algorithm has been developed to improve this behavior. The under/over frequency function of the relay will cause it to operate within 30 ms.Digital state estimation is implemented to estimate the power system voltage amplitude and normal frequency and its rate of change. The techniques employed for static state estimation are least errors square technique [31–33], least absolute value technique [34–36]. While linear and non-linear Kalman filtering algorithms are implemented for tracking the system operating frequency, rate of change of frequency and power system voltage magnitude from a harmonic polluted environment of the system voltage at the relay location. Most of these techniques use the per-phasedigitized voltage samples, and assume that the three-phase voltages are balanced and contain the same noise and harmonics, which is not the case in real-time, especially in the distribution systems, where different single phase loads are supplied from different phases.An approach for identifying the frequency and amplitude of flicker signal that imposed on the nominal voltage signal, as well as the amplitude and frequency of the nominal signal itself is presented in this text. The proposed algorithm performs the estimation in two steps. While, in the first step the original signal is shifted forward and backward by an integer number of sample, one sample in this paper. The generated signals from such shift together with the original one are used to estimate the amplitude of the original voltage signal that composed of the nominal voltage and the flicker voltage, the average of this amplitude gives the amplitude of the nominal voltage. This amplitude is subtracted from the original identified amplitude to obtain the samples of the flicker voltage. In the second step, the argument of the signal is calculated by simply dividing the magnitude of signal sample with the estimated amplitude in step one. Computing the arccosine of the argument, the frequency of the nominal signal as well as the phase angle can be calculated using the least error square estimation algorithm. Simulation examples are given within the text to show the features of the proposed approach.2. Flicker voltage identificationGenerally speaking, the voltage during the time of flicker can be expressed as [2]:where AO is the amplitude of the nominal power system voltage, xO is the nominal power frequency, and /O is the nominal phase angle. Furthermore, Ai is the amplitude of the flicker voltage, xfi its frequency, and /fi its phase angle and M is the expected number of flicker voltage signal in the voltage waveform. This type of voltage signal is called amplitude modulated (AM) signal.2.1. Signal amplitude measurement::The first bracket in Eq. (1) is the amplitude of the signal, A(t) which can be written as:As such Eq. (1) can be rewritten asAssume that the signal is given forward and backward shift by an angle equals an integral number of the sampling angle. Then Eq. (3) can be written in the forward direction as:While for the backward direction, it can be written as:where h is the shift angle and is given byN is the number of samples required for the shift, fO is the signal frequency and m is the total number of samples over the data window size. Using Eqs. (4)–(6), one obtainsThe recursive equation for the amplitude A(k) is given by:Having identified the amplitude A(k), the amplitude of the nominal voltage signal of frequency x O can be calculated, just by taking the average over complete data window size as:Having identified the power signal amplitude AO, then the flicker voltage components can be determined by;This voltage flicker signal can be written as;where DT is the sampling time that is the reciprocal of the sampling frequency.2.2. Measurement of flicker frequencyWithout loss of generality, we assume that the voltage flicker signal has only one component given by, i = 1To determine the flicker amplitude Vf1(k) and the frequency xf1 from the available m samples, we may use the algorithm explained in Ref. [9]. The frequency is calculated fromWhile the amplitude can be calculated as:In the above equations v0 are the fist and second derivative of the flicker signal, they can be calculated, using the central forward and backward difference [9] as:2.3. Nominal voltage signal frequency and phase angleThe signal argument can be calculated fromwhere AR(k) is given byIn the above equation W0, u are the two parameters to be estimated from the available m samples of the argument AR(k). At least two samples are required for such a linear estimation.Eq. (17) can be written, for m samples, asIn vector form, Eq. (19) can be written as:where Z is m 1 measurements vector for the argument samples, H is m 2 measurements matrix the element of this matrix depend on the sampling time, sampling frequency, X is the 2 1 parameters vector to be estimated and f is m 1 error vector to be minimized. The minimum of f based on least error squares occurs when:The above two equations give directly the frequency and phase angle, in closed forms, for the signal under study. To have a practical approach those formulas should not be sensitive to noise and harmonics. One way to reduce those sensitivities is to use of least error squares algorithm, as we explained in Eq. (21), for the frequency estimation in the paper. In the following section we offer examples from the area of power system voltage flickers that can be considered as amplitude modulated signals.puter experimentsThe above algorithm is tested using amplitude modulated signal with one voltage flicker signal given by;The signal is sampled at 10000 Hz and is giving a forward shift and backward shift by one sample, h = 7.2 and 1000 samples are used. The power system voltage, 50 Hz signal, amplitude is estimated using the algorithm explained earlier, using Eqs. (8) and (9), and it has been found to that the proposed algorithm is succeeded in estimating this amplitude with great accuracy and is found be AO = 1.0. Fig. 1 gives the actualvoltage signal, the tracked signal and the voltage signal amplitude. Examining this figure reveals the following:The power voltage signal amplitude, 50 Hz, is almost 1 p.u., the average value of A(t), as that calculated using Eq. (9).The proposed technique tracked the actual signal exactly.The flicker signal frequency is estimated using 200 samples only with Eq. (13). Fig. 2 gives the estimated flicker voltage frequency at each sampling step. Examining this figure reveals that the proposed algorithm estimates the flicker frequency with great accuracy. The spikes, in these curves, are due to the value of the voltage flicker signal at this time of sampling which is very small, and looking to Eq. (13) one can notice that to calculate the frequency we divide by this value ceeded to estimate the flicker amplitude, except at the points of spikes, as we explained earlier in the frequency estimation.Another example has been solved, where the voltage signal has two flicker signals with different amplitude and frequency. The voltage signal in this case is given by The signal is sampled at 500 Hz and is giving a forward shift and backward shift by one sample, h = 7.2 and 500 samples are used. The voltage nominal amplitude is estimated using the technique explained earlier and has found to be one per unit, and the tracking voltage, using this technique, tracks the signal exactly as shown in Fig. 4.4.ConclusionsAn approach for identifying the frequency and amplitude of flicker signal that imposed on the nominal voltage signal, as well as the amplitude and frequency of the nominal signal itself is presented in this paper. The proposed algorithm performs the estimation in two steps; in the first step the original signal is shifted forward and backward by an integer number of sample, at least one sample. The new generated signals from such a shift together with the original one is used to estimate the amplitude of the original voltage signal that composed of the nominal voltage and theflicker voltage. The average of this amplitude gives the amplitude of the nominal voltage; this amplitude is subtracted from the original identified amplitude to obtain the samples of the flicker voltage. The frequency of the flicker voltage is calculated using the forward and backward difference for the first and second derivatives for the voltage flicker signal.In the second step, the argument of the signal is calculated by simply dividing the magnitude of signal sample with the estimated amplitude in step one. Calculating the arccosine of the argument, the frequency of the nominal signal as well as the phase angle can be calculated using the least error square estimation algorithm. Simulation examples are given. It has been shown that the proposed algorithm is succeeded in estimating the voltage flicker frequency and amplitude as well as the amplitude and frequency of the power voltage signal.The proposed algorithm can be used off-line as well as on-line. In the on-line mode we recommend the usage of a digital lead- lag circuit. Wile in the off-line mode; just shift the registration counter on sample in the backward direction and another on in the forward direction to obtain the required sample of the data window size.电力系统的额定电压,频率和电压闪变参数的测量摘要我们提出,在本文中,用于识别施加于标称电压信号电压闪变信号,以及标称信号本身的振幅和频率的频率和幅度的方法。
FFT和Hough变换在织物纹理方向检测上的应用_王蕾
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基金项目: 高等学校博士学科点专项科研基金 (No.20120093130001) ; 国家自然科学基金青年科学基金项目 (No.61203364) ; 江苏省 2011 年度普通高校研究生科研创新计划项目 (No.CXZZ11_0472) ; 江苏省 2012 年度普通高校研究生科研创新计划项目 (No.CXZZ12_0748) 。 作者简介: 王蕾 (1987—) , 女, 博士研究生, 主要研究领域为纺织数字图像技术; 厉征鑫 (1987—) , 男, 博士研究生, 主要研究领域为 纺织数字图像技术; 刘建立 (1980—) , 男, 博士, 副教授, 主要研究领域为纺织数字图像技术; 高卫东 (1959—) , 男, 博士, 教授, 主要研究领域为纺织数字图像技术。 E-mail: gaowd3@ 收稿日期: 2014-01-20 修回日期: 2014-03-25 文章编号: 1002-8331 (2014) 18-0039-05 CNKI 网络优先出版: 2014-04-09, /kcms/doi/10.3778/j.issn.1002-8331.1401-0332.html
航空发动机振动环境谱统计归纳方法及振动试验台复现
第 50 卷第 2 期2024 年 4 月Vol. 50 No. 2Apr. 2024航空发动机Aeroengine航空发动机振动环境谱统计归纳方法及振动试验台复现房剑锋(中国飞行试验研究院,西安 710089)摘要:为满足航空发动机及机载产品研制过程贴近使用环境的振动考核试验需求,需根据发动机实测振动数据给出振动考核试验所需的输入谱图。
依据GJB/Z 126-99中给出的环境测量数据归纳方法,建立了发动机实测振动环境谱统计归纳方法并通过程序实现。
利用发动机多架次实测试飞振动数据统计归纳得到发动机测点位置的振动实测谱。
基于能量等效及信号频域特征分布一致原则,将归纳得到的实测谱转化为可用于振动台输入的振动环境谱,并在振动台上进行了振动信号的复现试验。
结果表明:振动台输出信号与发动机实测振动信号频域分布特征一致,在统计频率带宽范围内振动总量最大相差5.7%,证明了转化方法是合理的,为航空发动机机载设备贴近使用环境的振动考核试验方法提供了真实的输入谱图。
关键词:振动数据;统计归纳;环境谱;振动试验台;复现;航空发动机中图分类号:V216.2+1;V231.92文献标识码:A doi:10.13477/ki.aeroengine.2024.02.022 Aeroengine Vibration Environment Spectrum Statistical Induction and Reproductionon Vibration Testing TableFANG Jian-feng(Chinese Flight Test Establishment,Xi’an 710089,China)Abstract:To meet the requirements of conducting vibration assessment tests under conditions close to the operating environment for the development of aeroengine and airborne products, it is necessary to provide the input spectrum required for the vibration assessment test based on the measured engine vibration data. Based on the induction method of environment measurement data provided in GJB/Z 126-99, a statistical induction method for vibration environment spectra measured engine vibration data was established and implemented through a program. The measured vibration spectra at engine measuring positions were obtained by statistical induction according to vibra⁃tion data from multiple actual test flights. Based on the principle of energy equivalence and consistent distribution of signal frequency domain characteristics, the spectra obtained using the induction method were converted into vibration environment spectra which can be used as the input for the vibration testing tables, and experiments for vibration signal reproduction were conducted on vibration testing tables. The results show that the frequency domain distribution characteristics of the output signal of the vibration testing table are consistent with that of the measured engine vibration signal. The maximum difference in the overall vibration within the statistical frequency bandwidth is 5.7%, which proves the rationality of the conversion method and the capability of providing real input spectra for vibration assessment tests of aeroengine airborne equipment under conditions close to the service environment.Key words:vibration data; statistical induction; environment spectrum; vibration testing table; reproduction; aeroengine0 引言在航空发动机试飞过程中振动信号的测量具有重要意义,一方面可用于发动机整机振动特性的确定,定位发动机整机振动故障[1],70%以上的故障都以振动的形式表现出来;另一方面可通过试飞测试数据获取发动机的整机振动环境,为机载设备振动考核试验提供真实的试飞数据谱图。
T型三电平并网逆变器有限集模型预测控制快速寻优方法
2021年4月电工技术学报Vol.36 No. 8 第36卷第8期TRANSACTIONS OF CHINA ELECTROTECHNICAL SOCIETY Apr. 2021DOI: 10.19595/ki.1000-6753.tces.200083T型三电平并网逆变器有限集模型预测控制快速寻优方法辛业春王延旭李国庆王朝斌王尉(东北电力大学现代电力系统仿真控制与绿色电能新技术教育部重点实验室吉林 132012)摘要三电平变流器控制系统采用有限集模型预测控制(FCS-MPC),滚动优化需要遍历所有开关状态,针对其导致处理器运算量增加、处理时间长的问题,提出一种T型三电平并网逆变器优化计算量的FCS-MPC方法。
通过构建基于电压预测的单目标代价函数,避免设计权重系数问题,减化单次寻优的步骤;根据直流母线电位分布选择冗余小矢量,实现中点电位平衡,使每个控制周期的预测次数减小至3次,提高寻优效率。
有限控制集在预测过程中将所包含矢量的加权误差二次方最小作为依据划分,并利用矢量角补偿系统延迟,提高预测精度,使并网电流质量得到改善。
搭建基于RT-Lab的功率硬件在环仿真系统和物理装置验证所提控制策略,实验结果验证了所提理论分析的正确性和控制策略的有效性。
关键词:有限集模型预测控制T型三电平中点电位平衡快速寻优中图分类号:TM464Finite Control Set Model Predictive Control Method withFast Optimization Based on T-Type Three-Level Grid-Connected Inverter Xin Yechun Wang Yanxu Li Guoqing Wang Chaobin Wang Wei (Key Laboratory of Modern Power System Simulation and Control & Renewable Energy Technology Ministry of Education Northeast Electric Power University Jilin 132012 China)Abstract Rolling optimization of Finite Control Set model predictive control (Finite Control Set-MPC, FCS-MPC) needs to traverse all the switch states in the three-level converter control system, which will cause the problems of increased processor calculation and long processing time. For this reason, this paper proposes a FCS-MPC method with optimized calculation amount of T-type three-level grid-connected inverter. By constructing a single objective cost function based on voltage prediction, the design of weighting factor is avoided and the steps of single optimization are reduced.For improving the efficiency of optimization, the redundant small vector is selected according to the DC bus potential distribution to balance the neutral-point potential and reduce the number of predictions per control cycle to 3 times. The finite control set is divided according to the minimum weighted error square of the included vectors in the prediction process, and the vector angle is used to compensate the system delay, thereby improving the prediction accuracy and the grid-connected current quality. A power hardware-in-the-loop simulation system based on RT-Lab and a physical device are established to verify the proposed control strategy. The results show that the proposed theoretical analysis is correct and the control strategy is effective.国家自然科学基金资助项目(U2066208)。
放射免疫测定英语
放射免疫测定英语一、“放射免疫测定”英语:Radioimmunoassay(RIA)二、英语释义A very sensitive in vitro assay technique that uses radiolabeled substances (e.g., hormones, antigens) to measure minute quantities of substances (such as antibodies or antigens) in a biological sample by exploiting the specific binding reaction between antigen and antibody.三、短语1. radioimmunoassay kit(放射免疫测定试剂盒)2. double - antibody radioimmunoassay(双抗体放射免疫测定)3.petitive radioimmunoassay(竞争性放射免疫测定)四、单词1. radio -(表示“放射;辐射;无线电”,如radioactive放射性的)2. immuno -(表示“免疫”,如immunology免疫学)3. assay(n. 化验;试验;分析;v. 化验;分析)五、用法1. 作名词- Radioimmunoassay is widely used in medical research.(放射免疫测定在医学研究中被广泛使用。
)- The results of the radioimmunoassay were very accurate.(放射免疫测定的结果非常准确。
)2. 作定语修饰名词- A radioimmunoassay method was developed to detect the hormone level.(一种放射免疫测定方法被开发出来用于检测激素水平。
采用网侧电流闭环控制的电能质量综合补偿方法_梅红明
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、 指令电流预测、 电流跟踪控制方
Fig. 3 图 3 单相等效电路结构图 Single-phase equivalent circuit configuration
法等多个方面进行了深入探讨,提出了电网电压不 平衡条件下的谐波检测算法、采用重复控制的延时 和死区补偿方法、基于灰色理论和模糊控制的指令 电流预测方法等。 这些控制方法的改进在一定程度上提升了 APF 装置的补偿效果。但检测负载电流的控制方法 本质上是开环控制系统,这些改进措施无法从根本 上消除由开环系统静差造成的谐波残余,特别是对 于动态变化的谐波负载。 此外,如文献[1]所指出的,由于 PWM 逆变器
GA(s)
图 1 检测负载电流控制方式的 APF 控制框图 Fig. 1 APF control block under load current control mode
对于这样的开环系统而言,其补偿效果很容易 受到测量精度、外部扰动、采样及控制延时等方面 的影响。负载电流的采样误差直接反映到补偿电流 的偏差中;电网电压不平衡、背景谐波等因素会对 指令电流提取和补偿电流生成产生干扰;采样、计 算延时、PWM 的死区等等也直接影响装置的补偿 性能。 文献[2]的分析结果表明,80 μs 的延时将会导 致 5 次谐波存在 12.56%的残余, 且随着谐波次数的 增加,谐波残余也成比例增大。文献[3]详细分析了 死区时间的影响,指出死区造成的输出电压幅值偏 差与死区时间、载波频率及直流母线电压成正比, 在 6.4 kHz 的开关频率下,10 μs 死区造成的输出电 压幅值偏差为直流母线电压的 6.4%, 此外死区还会 造成输出相位上的偏差。 近年来,许多学者针对检测负载电流控制方式 存在的问题开展了广泛研究,从延时及死区补偿、 谐波电流提取
数据采集外文翻译
中文1950字附录附录A外文资料Data CollectionAt present,the management of China’s colleges and universities’apartments are developing toward standardization and market development,accidents have occurred in electricity,while some colleges and universities have installed apart ment energy metering control system,however,these systems monitor the prevale nce of low level,billing accuracy is low,electricity-sharing,the network number o f the drawbacks of low extent.Therefore,improving the Energy Measurement m onitoring device has become more urgent.The issue of student hostels in colle ges and universities to monitor energy metering system to study,design the st udent hostels in colleges and universities of the electricity data collector apartm ent.Data acquisition, also known as data acquisition, is the use of a device th at collect data from outside the system and enter into an interface within the s ystem.Data acquisition technology is widely cited in the various fields.Such as camera, microphone, all data collection tools.Data is being collected has been c onverted to electrical signals of various physical quantities such as temperature, water level, wind speed, pressure, etc., can be analog, it can be digital.Sampl e collection generally means that a certain time interval (called the sampling p eriod) to repeat the same point of data collection.The data collected are mostly instantaneous value, but also a feature within a certain period of time value.A ccurate data measurement is the basis for data collection.Data measurement met hod of contact and non-contact detection elements varied.Regardless of which method and components are measured object does not affect the status and me asurement environment as a precondition to ensure the accuracy of the data.Ver y broad meaning of data collection, including continuous physical hold the collection across the state.In computer-aided mapping, surveying and mapping, desi gn, digital graphics or image data acquisition process may also be called, this time to be collected is the geometric volume (or include physical quantities, su ch as gray)data.[1] In today's fast-growing Internet industry, data collection has been widely used in the field of Internet and distributed data acquisition field has undergone important changes.First, the distributed control applications in i ntelligent data acquisition system at home and abroad have made great progres s.Second, the bus-compatible data acquisition plug-in number is increasing, and personal computer-compatible data acquisition system the number is increasing. Various domestic and international data collection machine has come out, the d ata acquisition into a new era.Digital signal processor (DSP) to the high-speed data processing ability an d strong peripherals interface, more and more widely used in power quality an alysis field, in order to improve the real-time and reliability.The DSP and micr ocomputer as the center of the system, realize the power system signal collecti on and analysis. This paper based on the FFT algorithm with window interpola tion electric system harmonic analysis, improves the accuracy of the power qua lity parameters. In electricity parameter acquisition circuit, by highaccuracy tran sformer and improve software synchronous communication sampling method to conduct electricity parameters of the acquisition.The system consists of two main components, mainly complete data acquis ition and logic control.To synchronous sampling and A/D converter circuit pri ority . The DSP development board(SY-5402EVM),complete data processing. T HE signal after transformer, op-amp into A/D converter, using DSP multi-chann el buffer (McBSP) and serial port (A/D connected, data collection and operatio ns. At the same time, adopt PLL circuit implementation synchronous sampling, can prevent well due to sampling synchronization and cause the measuring err or. The overall system diagram of the A/D converter chooses the Analog to pr oduce stats redetect (AD) company AD73360. The chip has six analogue input channel, each channel can output 16 the digital quantity. Six channel simultan eous sampling, and conversion, timeshare transmission, effectively reduce gener ated due to the sampling time different phase error. SY - 5402EVM on-board DSP chip is TI company's 16 fixed-point digital signal processor TMS320VC54 02. It has high costperformance and provide high-speed, bidirectional, multi-channel belt cushion, be used to serial port with system of other serial devices di rectly interface.The realization method of ac sample:In the field of power quality analysi s,The fast Fourier transform (FFT) algorithm analysis of electric system harmon ic is commonly used.and the FFT algorithm to signal a strict requirements syn chronous sampling. The synchronous sampling influence: it's difficult to accomp lish synchronous sampling and integer a period truncation in the actual measur ement, so there was a affect the measurement accuracy of the frequency spectr um leakage problem. The signal has to deal with through sampling and A/D c onversion get limited long digital sequence,the original signal multiplied by A r ectangular window to truncated. Time-domain truncation will cause the detuning frequency domain, spectrum leakage occurs. In the synchronous sampling, bec ause the actual signal every harmonic component can't exactly landed in freque ncy resolution point in, but fall between the frequency resolution points. But F FT spectrum is discrete, only in all sampling points, while in other places of s pectrum is not. Such through FFT and cannot directly get every harmonic com ponent, but only the accurate value in neighboring frequency resolution point v alue to approximate instead of, can cause the fence effect error.The realization method of synchronous sampling signal:According to provide different ways of sampling signal, synchronous sampling method and divided into software sync hronous sampling method and hardware synchronous sampling method is two k inds. Software is synchronous sampling method by micro controller (MCU) or DSP provide synchronized sampling pulse, first measured the measured signal, the sa mpling interval period T Δ T = T/N (N for week of sampling points), T hus the count value determined timer,Use timing interrupt way realization sync hronous sampling. The advantage of this method is no hardware synchronous c ircuit, simple structure .This topic will be the eventual realization of access to embedded systems,the realization of the power measurement and monitoring,m onitoring system to meet the electricity network,intelligence requirement,it prom ote the development of remote monitoring services,bringing a certain degree of socio.economic effectiveness.On the fundamental reactive current and harmonic current detection, there are mainly 2 ways: First, the instantaneous reactive power theory based method, the second is based on adaptive cancellation techniques.In addition, there areother non-mainstream approach, such as fast Fourier transform method, wavelet transform.Instantaneous power theory based on the method of offensive principles ar e: a three-phase current detection and load phase voltage A, the coordinate tra nsformation, two-phase stationary coordinate system the current value, calculate the instantaneous active and instantaneous reactive power ip iq,then after coor dinate transformation, three-phase fundamental active current, with the final loa d current minus the fundamental current, active power and harmonic currents a re fundamental iah, ibhi, ich.From:Principles of Data Acquisitio数据采集目前,我国高校公寓管理正在向着正规化、市场化发展,在不断提高学生方便用电的同时,用电事故频有发生,虽然部分高校公寓已经安装了电能计量监控系统,但这些系统普遍存在着监控程度低、计费精度不高、电费均分、网络程度低等诸多端。
电力系统谐波测量算法
In order to satisfy the real-time requirements, the FFT operation means with good performance based on complex sequence is introduced into the harmonic analysis; In order to reduce the error because of asynchronous sampling, this paperuses polynomial approximation method oftheeffective form of cubic spline function to obtain the polynomial approximation formulas for frequency and amplitude correction based on the Blackman-harris window.
基于摩擦纳米发电机的柔性可穿戴多功能压力传感器
摘要随着社会的日益进步,医疗水平不断提高,互联网技术快速发展,健康和信息安全成为人们最为关注的焦点。
目前医疗资源的短缺和屡见不鲜的个人信息泄露事件,越来越成为人们的心头之患。
在健康方面,社会老龄化进一步加剧,各类慢性疾病的数量逐年增长,人们越来越意识到医院治疗已不能满足自身健康的需求,日常生活中更需要仪器设备实现自身健康状态长期持续的监测。
在信息安全方面,虽然人们采用密码、U盾及密保等方式保护个人信息,但个人信息依旧被窃取,泄漏在互联网等媒介之上。
如果日常生活中对人们的健康状态进行持续监测,并使用一种独一无二的身份识别方式,将大大减少各类慢性疾病的数量及个人信息泄露的问题。
目前部分可穿戴设备可用于人体生理信号的测量,实现对人体健康状态的检测。
每个人的生物特征是独一无二的,将生物特征用于身份识别,信息将很难被窃取。
但是目前存在的可穿戴设备无法实现健康状态监测和身份识别双重功能。
为此,本文做了以下研究:①本文研究了基于摩擦纳米发电机的柔性可穿戴多功能压力传感器。
该传感器以人耳鼓膜结构进行仿生,结合单电极式摩擦纳米发电机工作模式,采用PTFE 薄膜、Nylon薄膜、ITO薄膜以及PET衬底制作而成。
结合薄膜的振动特性从理论上分析了传感器的振动模态,采用单电极摩擦纳米发电机的工作原理分析传感器的电学输出特性,采用COMSOL Multiphysics对传感器的振动特性和开路电压进行了仿真,验证了设计的传感器具有较宽的工作频带范围,高低频特性较好。
②对传感器测得信号中的噪声进行了分析及处理。
对传感器输出信号中的工频干扰、肌电漂移、运动伪迹和基线漂移噪声进行处理。
采用模拟滤波和数字滤波相结合的方式,对传感器输出信号进行处理。
结合传感器输出信号频谱中信号频率分布,采用10Hz Butterworth低通滤波器和45Hz~1500Hz Butterworth带通滤波器对测量的信号进行了分解,分别得到脉搏波信号和喉咙声信号。
Fairchild 锐捷半导体 FSB50550T Motion SPM 5 FRFET 系列数据手
FSB50550T Motion SPM® 5 FRFET® SeriesApril 2013FSB50550TMotion SPM ® 5 FRFET ® SeriesFeatures•500 V R DS(on)= 1.7 Ω (Max ) FRFET MOSFET 3-Phase Inverter Including HVICs •Three Separate Negative DC-Link Terminals for Inverter Current Sensing Applications •HVIC for Gate Driving and Undervoltage Protection •Active-High Interface, Can Work With 3.3 V / 5 V Logic •Optimized for Low Electromagnetic Interference •Isolation Voltage Rating of 1500 Vrms for 1 min.•Extended VB Pin for PCB IsolationApplications•3-Phase Inverter Driver for Small Power AC Motor DrivesGeneral DescriptionFSB50550T is a Motion SPM5 Series Based on Fast-Recovery MOSFET(FRFET) Technology as a Compact Inverter Solution for Small Power Motor Drive Applications Such as Fans and Pumps. It is Composed of Six FRFET MOSFETs and Three Half-Bridge Gate Drive HVICs. FSB50550T Provides Low Electromagnetic Interference(EMI) Characteristics with Optimizing Switch -ing Speed. Moreover, Since It Employs MOSFETs as Power Switches, It has Greater Ruggedness and a Larger Safe Operating Area(SOA) than IGBT-Based Power Modules. The Pakage is Optimized for Thermal Performance and Compactness for use in Applications Where Space is Limited. FSB50550T is the Right Solution for Inverters Requiring Energy Efficiency,Compactness, and Low Electromanetic Interference.Related Source•AN9042 : Motion SPM5 Series Ver.1 User’s Guide •AN-9082 : Motion SPM5 Series Thermal Performance by Contact PressurePackage Marking & Ordering InformationDevice MarkingDevicePackageReel SizePacking TypeQuantityFSB50550TFSB50550TSPM5F-023-RAIL15Thermal Resistance Total System Note:1. For the Measurement Point of Case Temperature T C , Please refer to Figure 4.2. Marking “ * “ Is Calculation Value or Design Factor.SymbolParameterConditionsRatingUnitR θJCJunction to Case Thermal ResistanceEach MOSFET under Inverter Oper-ating Condition (Note 1)8.6°C/WSymbolParameterConditions RatingUnitT J Operating Junction Temperature -20 ~ 150°C T STG Storage Temperature -50 ~ 150°C V ISOIsolation Voltage60 Hz, Sinusoidal, 1 minute, Con-nection Pins to Heatsink1500V rmsControl Part (Each HVIC Unless Otherwise Specified) Note:1.BV DSS is the Absolute Maximum Voltage Rating Between Drain and Source Terminal of Each MOSFET Inside Motion SPM ®. V PN Should be Sufficiently Less Than This Value Considering the Effect of the Stray Inductance so that V DS Should Not Exceed BV DSS in Any Case.2. t ON and t OFF Include the Propagation Delay Time of the Internal Drive IC. Listed Values are Measured at the Laboratory Test Condition, and They Can be Different Accordingto the Field Applications Due to the Effect of Different Printed Circuit Boards and Wirings. Please see Figure 4 for the Switching Time Definition with the Switching Test Circuit of Figure 5.3. The peak current and voltage of each MOSFET during the switching operation should be included in the safe operating area (SOA). Please see Figure 5 for the RBSOA testcircuit that is same as the switching test circuit.E OFF -11-µJRBSOAReverse-Bias Safe Oper-ating AreaV PN= 400 V, V CC = V BS = 15 V, I D = I DP , V DS =BV DSS ,T J = 150°CHigh- and Low-Side MOSFET Switching (Note 3)Full SquareSymbolParameterConditionsMinTyp MaxUnitI QCC Quiescent V CC Current V CC =15 V, V IN =0V Applied Between V CC and COM--160µA I QBS Quiescent V BS Current V BS =15 V, V IN =0VApplied Between V B(U)-U, V B(V)-V, V B(W)-W--100µA UV CCD Low-Side Undervoltage Protection (Figure 6)V CC Undervoltage Protection Detection Level 7.48.09.4V UV CCR V CC Undervoltage Protection Reset Level 8.08.99.8V UV BSD High-Side Undervoltage Protection (Figure 7)V BS Undervoltage Protection Detection Level 7.48.09.4V UV BSR V BS Undervoltage Protection Reset Level 8.08.99.8V V IH ON Threshold Voltage Logic High Level Applied between IN and COM 2.9--V V IL OFF Threshold Voltage Logic Low Level --0.8V I IH Input Bias CurrentV IN = 5V Applied between IN and COM-1020µA I ILV IN = 0V--2µAFSB50550T Motion SPM® 5 FRFET® Series* EZSWITCH™ and FlashWriter ® are trademarks of System General Corporation, used under license by Fairchild Semiconductor.DISCLAIMERFAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION, OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS.THESE SPECIFICATIONS DO NOT EXPAND THE TERMS OF FAIRCHILD’S WORLDWIDE TERMS AND CONDITIONS, SPECIFICALLY THE WARRANTY THEREIN, WHICH COVERS THESE PRODUCTS.LIFE SUPPORT POLICYFAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF FAIRCHILD SEMICONDUCTOR CORPORATION.As used herein:1. Life support devices or systems are devices or systems which, (a) areintended for surgical implant into the body or (b) support or sustain life,and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user.2.A critical component in any component of a life support, device, system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.PRODUCT STATUS DEFINITIONS Definition of TermsBuild it Now™CorePLUS™CorePOWER™CROSSVOLT ™CTL™Current Transfer Logic™EcoSPARK ®EfficentMax™EZSWITCH™ *™Fairchild ®Fairchild Semiconductor ®FACT Quiet Series™FACT ®FAST ®FastvCore™FlashWriter ® *FPS™F-PFS™FRFET ®Global Power Resource SM Green FPS™Green FPS™ e-Series™GTO™IntelliMAX™ISOPLANAR™MegaBuck™MICROCOUPLER™MicroFET™MicroPak™MillerDrive™MotionMax™Motion-SPM™OPTOLOGIC ®OPTOPLANAR ®®PDP SPM™Power-SPM™PowerTrench ®PowerXS™Programmable Active Droop™QFET ®QS™Quiet Series™RapidConfigure™™Saving our world, 1mW /W /kW at a time™SmartMax™SMART START™SPM ®STEALTH™SuperFET™SuperSOT™-3SuperSOT™-6SuperSOT™-8SupreMOS™SyncFET™®The Power Franchise ®TinyBoost™TinyBuck™TinyLogic ®TINYOPTO™TinyPower™TinyPWM™TinyWire™TriFault Detect™µSerDes™UHC ®Ultra FRFET™UniFET™VCX™VisualMax™XS™®Datasheet Identification Product Status DefinitionAdvance InformationFormative / In DesignDatasheet contains the design specifications for product development. Specifications may change in any manner without notice.ANTI-COUNTERFEITING POLICYFairchild Semiconductor Corporation’s Anti-Counterfeiting Policy. Fairchild’s Anti-Counterfeiting Policy is also stated on our external website,, under Sales Support .Counterfeiting of semiconductor parts is a growing problem in the industry. All manufactures of semiconductor products are experiencing counterfeiting of their parts. Customers who inadvertently purchase counterfeit parts experience many problems such as loss of brand reputation, substandard performance, failed application, and increased cost of production and manufacturing delays. Fairchild is taking strong measures to protect ourselves and our customers from the proliferation of counterfeit parts. Fairchild strongly encourages customers to purchase Fairchild parts either directly from Fairchild or from Authorized Fairchild Distributors who are listed by country on our web page cited above. Products customers buy either from fairchild directly or from Authorized Fairchild Distributors are genuine parts, have full traceability, meet Fairchild’s quality standards for handing and storage and provide access to Fairchild’s full range of up-to-date technical and product information. Fairchild and our Authorized Distributors will stand behind all warranties and will appropriately address and warranty issues that may arise. Fairchild will not provide any warranty coverage or other assistance for parts bought from Unauthorized Sources. Fairchild is committed to combat this global problem and encourage our customers to do their part in stopping this practice by buying direct or from authorized distributors.。
基于FAST-SURF的移动端实时特征检测匹配算法
2016年第5期
文 章 编 号 :10 9—2552(2016}05-0091—04 DOI:10.13274/j.cnki.hdzj.2016.05.024
基 于 FAST—SURF的移 动端 实 时特 征 检 测 匹配算 法
尤 智 ,刘惠义
(河海大学计算机与信息学 院,南京 21110 )
收稿 日期 :2015—07—16 作者简 介 :尤智 (1991一),男 ,硕士研究 生 ,研究 方 向为增 强现实 、
计算 机图形学 。
一
Байду номын сангаас
9l 一
测 器应该 立 即探 测 周边 环 境 ,并 将 实 时数 据 回复 给 用 户 。
3 实验结果 和分 析
根据 文 中前 面 的 描述 ,搭 建 了智 能 入 侵 检 测 系 统来评估 系统的响应时问及 电池寿命等指标。入侵 检测系统对响应时间有严格 的要求 ,在该应用 中,要 求人 侵事 件 发 生 后 5秒 之 内控 制 器 节 点 应 该 发 出 通 知 。
电源保护解决方案:Eaton 93PR UPS说明书
Power Quality SolutionsEaton 93PR UPST aking energy efficiency andscalability to the next levelEaton’s heritage in industry-leading UPS design and productionFor more than 50 years, Eaton has beensafeguarding the critical systems of businessesacross the globe. Whether protecting a singledesktop or the largest data centre, Eatonsolutions provide clean, uninterrupted powerto keep mission-critical applications working.We offer a comprehensive range ofenvironmentally-sensitive, efficient, reliableUPSs, surge protective devices, powerdistribution units (PDUs), remote monitoring,meters, software, connectivity, enclosures,airflow management and professional services.We work with IT and facilities managers toeffectively manage power in virtually everybusiness segment, including data centres,retail outlets, healthcare organisations,governmental agencies, manufacturing firms,broadcasting companies, financial institutions,and a wide variety of other applications.Our solutions provide the power tomake a difference, helping you achieveyour business goals while maintainingenvironmentally sustainable enterprises.A world-class support structureAs an industry-leading UPS provider, at Eatonwe’re constantly working to ensure that ourservice standards meet your needs precisely.Our trained service team is on hand 24/7 tominimise risks by detecting and addressingproblems before they happen. In East Asia,this service network consist of field engineerswho receive comprehensive, up-to-date trainingon the latest products and technologies.The experience and know-how of ourservicing resources provide a dedicatedsupport package which helps to ensureyour equipment is running safely, reliably,sustainably and energy-efficiently at all times.2 EAton 93PR UPSEaton 93PR UPS 25-200 kWLowest total cost of ownership and maximum availability – taking scalability, resiliency, safety and efficiency to the next level.The most advanced UPS in its power range, the Eaton 93PR is ideal for small to mid-sized data centres and other mission critical applications where efficiency, reliability, safety and scalability are essential.Future-readyThe rapid adoption of the cloud, constant evolution of IT technologies, increased focus on environmental footprint and sophistication of mission critical applications is demanding even more efficient, resilient, scalable and safe power protection solutions.The new levels of efficiency and scalability offered by the 93PR minimise Total Cost of Ownership while the safety and resiliency, both in infrastructure and IT layers, maximise availability and ensure business continuity.All-round valueAvailable in 200kW frame sizes, the modular design of the 93PR enables it to suit a wide range of requirements. And, whichever one you choose, you can be sure it will provide the lowest Total Cost of Ownership combined with maximum availability, for cost-efficient business continuity.Ensuring that you can always access the power your mission critical application requires – under all circumstances – withoutcompromising business performance or safety, the 93PR is the most efficient, scalable, Cloud-ready and safe UPS you can choose.SafetyEnsuring safety in any electrical installation is a must. Safe hot-swappable design and in-built back-feed protection ensures safety and compliance with regulations.EfficiencyWith high efficiency being translated into reduced electrical and cooling losses, the 93PR helps to minimiseoperational expenditure costs, in addition to addressing the cost pressures resulting from commoditisation of IT services. Increased efficiency also leads to higher sustainability, through reduced carbon emissions. ScalabilityScalability helps to optimise capitalexpenditure by only deploying additional equipment when necessary and providing additional flexibility to respond to your changing needs. The scalability of the 93PR also provides increased flexibility to accommodate the changing requirements of rapidly evolving technologies.Resiliency, virtualisation & cloud-readinessThe ability of a system to absorb faults and still remain in its desired operational state is paramount to minimising costly downtime. The 93PR takes resiliency to the next level by bridging electrical and IT infrastructures./ups 3the Eaton 93PR is simply the most efficient UPS in its class, offering the lowest t otal Cost of ownership. t hanks to Eaton’s advanced algorithms and energy- saving features, the 93PR achieves up to 99% efficiency. t his efficiency is well proven with installations in major datacentre hubs in the Asia Pacific region and around the world.Maximum Energy Efficiency Lowest TCO4 EAton 93PR UPS99% efficiency - Energy Saver System (ESS) Eaton’s ESS enables the 93PR efficiency to reach an impressive level of 99% by suspending the power modules when power conditioning is not required.The power is fed through the static bypass switch, and in the event of exceeding pre-set input limits, the UPS is ready to switch to double-conversion mode in under two milliseconds. In addition to extremely low losses, the ESS mode provides filtering against fast low-energy transients. It is simply the most advanced, most reliable, fastest-reacting energy-saver architecture available.In addition to saving energy, this technology enhances the reliability of the system by reducing electrical stress in the power electronic components, extending the UPS life time and thus reducing total cost of ownership.Maximum double conversion efficiencyThe 93PR still offers the highest double conversion efficiency in the market, reaching above 96%.Highest power densityThe unity power factor maximises the true available power of the 93PR. This means it can deliver up to 20% more real power than other UPSs in its class. The 200kW frame can house an internal Maintenance Bypass Switch(MBS) or DC breaker.The highly scalable nature of the 93PR means that scaling up in response to increased demand takes minutes rather than hours. Scaling up can also be achieved without increasing the footprint – saving valuable floor space. The modular design allows for internal redundancy, which eliminates the need for an additional UPS for N+1 configurations.External redundancy also improves scalability, by paralleling up to 4 frames for a total system size of up to 800 kW.The 93PR 25kW UPM (Uninterruptible Power Module)optimised double conversion efficiency - Variable Module Management System (VMMS)For applications where ESS may not be optimal, for example with very low quality mains, VMMStechnology includes automatic variable power module management. The system automatically suspends and engages modules as appropriate, to optimise efficiency both at UPS and system level.VMMS helps you achieve high efficiency even when UPS load levels are low – typical for redundant UPS systems.VMMS can optimise the load levels of power modules in a single 93PR UPS or in parallel systems, by suspending extra UPS capacity. This means not only greater efficiency at lower load levels, but optimum efficiency at all load levels.Eaton 93PR Efficiency in all modesU P S E f fi c i e n c y (%)Load (% of nominal)of the Eaton 93PR UPS. It ensures you can always access the power your mission-93PR 200kW FrameHot swappable and hot scalableDue its modular design, a 93PR power module can be replaced or added while another module continues protecting the load. This eliminates the need to go to bypass for module replacement or upgrading (MTTR: 0 minutes). Replacement and upgrade (N+1) operations typically take less than 10 minutes.Centralised topologyThe centralised topology of the 93PR is ideal for scalable systems, as it provides full bypass capacity from day one, whereas modular designs with static switches in every power module can have a severe negative impact on the selectivity of the system due to undersized static bypass. This can compromise the availability of the overall system./ups5Take complete controlthe complete solutionThe Eaton 93PR UPS is designed for the most advanced IT environments, and it comes with interfaces for Web and SNMP as standard.In the event of an alert, the UPS system notifies users and administrators by email. If there’s a prolonged power failure, the protected computer systems can be shut down smoothly using the Intelligent Power ® Protector software also incorporated with the 93PR.Y our 93PR can be connected directly to your corporate network and the internet. This means you can monitor and manage your UPS through a standard web browser.Information, access, ease of useIntelligent Power Manager ® (IPM) can be used to monitor and manage all Intelligent Power Protectors running in the network. This dramatically reduces the administrator’s workload, and minimises the possibility of error.The web-based interfaces of the Intelligent Power software simplify usage, by allowing access from any computer in the LAN, as well as remotely via the internet. Power information is consolidated in the same tool used to monitor and manage physical and virtual servers, storage and networks.In the event of power failure, IPM can trigger protective actions such as live migration of virtual machines, controlled shutdown, or disaster recovery.6EAton 93PR UPSManaging and controlling your 93PR UPS is easy. Designed for the most advanced It environments, the 93PR comes equipped with intuitive userinterfaces, a large touchscreen LCD providing useful status information and back logs, and a full suite of power management and connectivity options.Intelligent, intuitive, integralThe world-class Intelligent Power Manager intelligent software solution of your 93PR UPS plugs into leading virtualisation management systems, including VMware vCenter, Microsoft SCVMM and Citrix XenCenter.This user-friendly monitoring tool enables you to monitor and manage your UPS system as an integral part of your power infrastructure. It collects data through the network, then stores it in a database for viewing and analysis.Easy managementThe 93PR provides easier access to detailed status information through its large, user-friendly 7” LCD touchscreen interface.With the 93PR’s graphical LCD interface you can trackstats on energy savings, battery time, outage tracking, load profiling and much more.The green/yellow/red LED light-bars make system statusvisible from a distance in data centres.VSPEX L ABSVALIDATED/ups7UPS output power rating (1.0 p.f.)25, 50, 75, 100, 125, 150, 175, 200kW Efficiency in double conversion mode > 96%Efficiency in Energy Saver System (ESS) > 99%Static bypass rating 200kWExternal paralleling up to 4 units with HotSync technology UPS topologyDouble conversion UPS degree of protectionIP20Acoustic noise at 1 m, in 25 °C ambient temperature < 70 dBA in double conversion, < 55 dBA in ESSAltitude (max) 1000m above sea level at 40 °C. Maximum 2000m with 1% derating per each add. 100 m Rated input voltage220/380 V, 230/400 V, 240/415 V 50/60 Hz Voltage tolerance - Rectifier input 187 to 276 VVoltage tolerance - Bypass input rated voltage -15% / +10%Rated input frequency 50 or 60 Hz, user configurable Frequency tolerance 40 to 72 HzInput wiring3 phase + neutral Input power factor at 100% load > 0.99Input ITHD< 3%Rated input r.m.s current 25kW 50kW 75kW 100kW 125kW 150kW 175kW 200kW 380V 40 A 80 A 120 A 159 A 199 A 239 A 278 A 318 A 400V 38 A 76 A 114 A 151 A 189 A 227 A 264 A 302 A 415V37 A 73 A 110 A 146 A 182 A 219 A 255 A 291 ASoft start capabilityYes Internal backfeed protection YesOutput wiring3 phase + neutralRated output voltage rating 220/380 V, 230/400 V, 240/415 V, configurableTotal voltage harmonic distortion < 1% (100% linear load); < 5% (100% non-linear load)Output power factor1.0Permitted load power factor 0.8 lagging to 0.8 leadingOverload on inverter 10 min 102-110%, 60 sec 111-125%, 10 sec 126-150%, 300 ms > 150%.Overload on bypass Continuous < 125%, 20 ms 1000%Battery type 12V, VRLACharging methodABM technology or Float Temperature compensation Optional Battery nominal voltage (VRLA) 480 VBattery quantity 36 to 44 blocks. Default is 40 blocksCharge current limit Default 5A, configurable maximum 25A per UPM Battery start capability YesMinislot3 communication bays Network/SNMP interface Yes, optionalSerial portsBuilt-in host and device USBStandard connectivity ports Mini-slot ports for optional cards, Device USB and Host USB, RS-232 service port, relay output, External Battery Cabinet(EBC) Parallel Tie Cabinet(PTC)External Maintenance Bypass Switches(EMBS)Safety IEC 62040-1EMCIEC 62040-2Performance IEC 62040-3730-80492-00P Eaton 93PR 25kW (UPM) Uninterruptible Power Module 25KW460 x 600 x 130 289106-42218-00P Eaton 93PR 200kW Frame, internal back-feed200KW max 603 x 1013 x 2050 3109106-42217-00PEaton 93PR 200kW Frame, internal back-feed, MBS200KW max603 x 1013 x 2050368Due to continuous product improvement programmes, specifications are subject to change without notice.Eaton 93PR UPS 25-200 kW • /upsEaton is dedicated to ensuring that reliable, efficient and safe power is available when it’s needed most. With unparalleled knowledge of electrical power management acrossindustries, experts at Eaton deliver customised, integrated solutions to solve our customers’ most critical challenges. Our focus is on delivering the right solution for the application. But, decision makers demand more than just innovative products. They turn to Eaton for an unwavering commitment to personal support that makes customer success a top priority.Eaton is the trade name, trademark, and/or service mark of Eaton Corporation or its subsidiaries and affiliates.® 2015 Eaton Corporation All Rights Reserve Printed in Singapore 93PR_25-200kW_8PP_EA September 2015Sales enquiries for Bangladesh, Cambodia, Myanmar and Laos, please contact our Thailand office.SINGAPORET +65 6825 1684E ******************KOREAT + 82 2 6238 7949E **********************THAILANDHONG KONGT + 852 2830 3077E *************************MALAYSIAT + 603 7804 3618E ******************VIETNAMT + 84 4 393 65 303E ******************INDONESIAT + 62 21 29499 000 E ******************PHILLIPINEST + 63 (2) 812 3045E ******************HCMCHANOIT + 84 86255 6737E ******************For more information, visit /ups。
低时延通信中的变电站电源设备异常振动状态智能检测
Telecom Power Technology电源与节能技术低时延通信中的变电站电源设备异常振动状态智能检测陈咏龄(国网湖北省电力有限公司黄冈供电公司,湖北为提高变电站电源设备运行的安全性,以低时延通信环境为基础,设计了变电站电源设备异常振动状态在低时延通信环境下估计变电站电源设备频率后,通过时间序列筛选变电站电源设备异常振动数据集。
在此基础上,利用训练后的决策树算法,输出异常振动状态检测结果。
实验结果表明,应用所提出方法后,检测准以上,说明该方法的检测性能良好。
低时延通信;变电站电源设备;异常振动检测;决策树算法Intelligent Detection of Abnormal Vibration State of Substation Power Supply Equipment inLow Delay CommunicationCHEN Yongling(Huanggang Power Supply Company, State Grid Hubei Electric Power Co., Ltd., Huanggangsafety of substation powerdetection method for abnormal vibration status of substation power equipment based on a low delay communication 2023年10月10日第40卷第19期113 Telecom Power TechnologyOct. 10, 2023, Vol.40 No.19陈咏龄:低时延通信中的变电站电源设备异常振动状态智能检测个子载波中选择一定距离的载波信道[4]。
当信道变化缓慢且变电站设备处于正常运行状态时,捕获阶段的信号可以表示为()0maxFj x R e w φ== ∑(2)式中:R (e )为经过校正后的信道信号;w 为同步信道位置;φ为相同子信道中的传送结果;F 为帧数。
C-Trak Apollo 无线 有线伽马探头用于射线引导手术说明书
C-Trak ApolloWireless/Wired Gamma Probe for radio guided surgeryStored Timed CountsStorage of timed counts eliminating the need for manual transcription.Key FeaturesWireless or wired probe connectivityEasy switching between wiredStart timed count from Apollo handset.Storage of timed counts eliminatingthe need for manual transcription.• Large touchscreen displayfor maximum visibility.• Manual or Auto-range capabilities.• Max count feature.• Fast calibration and enhanceddiagnostics quickly ensure correct functioning.• Multiple probes can be storedwithin the software for use in a range of procedures.Charging Dockrepresentation of where the specimen of interest is, especially if deep within the tissue.The C-Trak Apollo system uniquely eliminates scattered radiation, therefore providing superior directionality. The surgeon can then dissect in the right direction to find the tissue of interest, making smaller incisions and dissecting less healthy tissue in the process.®>1300 CPS/MBq for Co-57 (distance of 30 mm in scatter)> 99.9%@140 keV15 mm with collimator, 11 mm without collimatorCsI (Caesium Iodide) detection technology. Superior patented collimator technology.collimator is optimised for the most common procedures like breast (axillary) sentinel lymph node Biopsy.Our Omniprobe Lechner Collimator narrows directionality further with a smaller aperture and is optimal for head-neck procedures or others where subjects are often overshadowed by the injection site.the C-Trak Apollo System can be fitted with alternative probes for specialist applications.is available in either straight or angled orientation.PET used for detecting FDG and other PET emitting isotopes. EL for Laparoscopic use (available in 0°, 20° or 90°).OmniProbe ELOmniProbe PETSpecification for C-Trak Apollo Wireless HandsetRechargeable LiITypically 4 h continuous use(sleep mode for battery conservation)2 hours using dockMobile workstation to store all system components.Foot pedal for optional use with wired probe system.OmniProbeEurope & WorldwideSouthern Scientific LimitedScientific House, The Henfield Business Park Shoreham Road, Henfield, BN5 9SL, UKE-mail:**************************.uk Tel:+44 (0)1273 497600 USA & CanadaC/o LabLogic Systems, Inc. 1911 N US HWY 301, Suite 140 Tampa, FL 33619, USAE-mail:****************** Tel:+1-813-626-6848 Service and SupportCare Wise understand the need for outstanding services to minimise instrument downtime and maximise reliability. The most cost effective way to do this is through our service contracts, which include:• Annual Preventative Maintenance (return to base) − Annual preventative maintenance checks on yourinstrument to ensure system reliability.• 50% discount on parts and labour forrepairs due to accidental damage.• Protection against mechanical failures (repair at no cost) − Should your system suffer mechanical failure Care Wise will provide a full repair at no additional cost.• Loan units at no charge should your components ever require repair (subject to availability) −Care Wise will send you a loan instrument whilstmaintenance work is being carried out on yoursto ensure there is no instrument downtime.• A new calibration check source after 18 months. ISO CertifiedSouthern Scientific Ltd is certified to ISO 9001 andISO 13485 representing the high level of quality assurance and management that we provide at every stage of the supply process, whether a product is distributed on behalf of our trusted manufacturers or constructed in our UK workshop. This accreditation means that our customers can place an order knowing that the delivered product will be suitable for its intended use, fully compliantwith EU legislation and in full working order.All our products are CE marked.。
高考英语任务型阅读信息分类与整合练习题30题
高考英语任务型阅读信息分类与整合练习题30题1<背景文章>In today's digital age, technology has had a profound impact on education. The integration of technology in the classroom has transformed the way students learn and teachers teach. Online learning platforms, educational apps, and virtual reality tools are just some of the ways technology is enhancing the educational experience.One of the major benefits of technology in education is its ability to provide personalized learning. With the help of adaptive learning software, students can receive customized lessons based on their individual needs and learning styles. This not only helps students learn at their own pace but also increases their engagement and motivation.Another advantage of technology in education is its accessibility. Students can access educational resources from anywhere in the world, at any time. This has opened up new opportunities for learning and has made education more inclusive.Technology has also made it easier for teachers to track student progress and provide feedback. With the use of learning management systems, teachers can monitor student performance, identify areas of weakness, and provide targeted interventions.However, like any tool, technology also has its limitations. One of the challenges of using technology in education is the digital divide. Not all students have access to the same technology resources, which can lead to inequalities in education. Another concern is the potential for distraction. With the availability of social media and other online distractions, students may find it difficult to focus on their studies.Despite these challenges, technology is here to stay and will continue to shape the future of education. As educators, it is our responsibility to ensure that technology is used effectively to enhance the learning experience and not become a distraction.1. Technology in education can provide ___.A. traditional learning methodsB. one-size-fits-all lessonsC. personalized learningD. limited educational resources答案:C。
电能质量检测
电能质量动态检测技术的研究摘要随着电力电子技术的飞速发展,各种电力电子装置在工业、生活及高新技术领域获得了广泛应用,它在给人们带来巨大经济效益的同时,也带来了严重谐波污染、无功浪费等问题。
针对这一问题,广大的学者将目光投向有源电力滤波器(Active Power Filter,APF)的研究。
APF公认为是治理电网谐波及无功污染、改善电能质量最有效的装置[1],它能有效的抑制电力系统中非线性负载引起的谐波污染,已成为电力电子技术应用中一个比较新的研究热点。
谐波电流检测方法是有源电力滤波器研究的关键技术之一,直接关系着有源电力滤波器的性能好坏[2]。
提高谐波电流检测技术水平对提高有源电力滤波器的性能具有十分重要的意义。
本文首先介绍了有源电力滤波器的基本结构和工作原理,并对一些常规的谐波电流检测方法的优缺点进行了比较。
其次,针对传统的谐波电流检测方法的缺陷,提出将神经网络与基于噪声抵消原理的自适应谐波检测相结合,利用径向基函数运算量小、收敛快、无局部极小值等优点,构造了一种基于径向基函数神经网络的谐波电流检测方法,仿真结果表明该检测方法具有很好的动态响应及畸变电流检测精度。
最后,设计了一套实验系统,对本文所采用的系统方案进行了实验验证。
仿真表明,本文所采用的有源电力滤波器检测系统方案切实可行,能够较好地实现动态检测谐波和无功功率的目的。
关键词:谐波和无功功率检测;径向基函数神经网络;有源电力滤波器。
Dynamic Power Quality Testing TechnologyResearchAbstractWith the rapid development of power electronics technology, v arious electronic devices in the power industry, life and high-tech fields access to wider use. It brought great economic benefits to the people at the same time, it also brings serious harmonic pollution, waste and other issues of reactive power.To address the issues, the majority of the scholars will be eyes on the study APF.APF(Active Power Filter) has been a key project in power electronics application technology, It can effectively curb the power system in the non-linear load caused by harmonic pollution.It is the most effective method to solve harmonic and reactive power currents pollution, and improve the power quality. Harmonic current detection is one of the key technologies of APF and due to its performance is good or bad.The improvement of harmonic current detection method is very important for improving the performance of APF.This paper, firstly, introduces the basic structure and principle of APF, and then makes comparison among some conventional harmonics detections methods. Secondly, contraposes the limitation of the traditional harmonic current detecting method based on neural network, presents the method that combines the neural network and auto adaptive harmonic current detecting method based on the principle of noise each other eliminating.As the characteristics that are small calculative quantity, fast converge, without local minimal point of Redial Basis Function (RBF), this dissertation forms a new harmonic current detecting method based on RBF. The simulation results show that the method has many advantages, such as good dynamic response, high accuracy. At last, A system is designed to verify the proposed APF scheme .The results of simulation show that the proposed APF scheme is practical and can detect harmonics and reactive power effectively.Key words: harmonics and reactive power;RBFNN ;APF.目录摘要 (1)Abstract (1)第一章绪论 (3)1.1引言 (3)1.2 电能质量的研究背景及发展现状 (3)1.2.1 电能质量的基本概念 (3)1.2.2 电能质量问题的产生 (3)1.2.3谐波的基本概念 (4)1.2.4 谐波的产生及危害 (6)1.2.5无功功率的基本概念 (7)1.2.6 无功功率的产生及对公共电网的影响 (10)1.3课题的目的及意义 (10)1.4课题的主要研究内容 (10)第二章有源电力滤波器 (11)2.1有源电力滤波器基本原理 (11)2.2本章小结 (12)第三章谐波电流的检测方法 (13)3.1 傅立叶变换法 (13)3.1.1 傅立叶变换的基本理论 (14)3.1.2傅立叶变换法的局限性 (18)3.2.小波变换法 (19)3.2.1 小波变换法基本理论 (20)3.2.2小波变换法的局限性 (21)3.3 自适应谐波检测法 (21)3.3.1自适应法的基本理论 (21)3.3.2自适应谐波检测法的局限性 (25)3.4 其他算法 (25)3.5 本章小节 (26)第四章神经网络的自适应谐波电流检测方法及仿真研究 (27)4.1基于径向基函数神经网络的自适应谐波检测方法 (27)4.1.1 RBF 神经网络的结构模型 (28)4.1.2 RBF 神经网络的参数调整 (30)4.2仿真研究 (33)4.2.1神经网络 SIMULINK 建模方法 (33)4.2.2检测电路的仿真模型的建立 (34)4.2.3仿真结果分析 (36)4.3本章小结 (39)第五章谐波电流检测系统的实验研究 (40)5.1 检测系统方案及技术实现 (40)5.1.1 硬件部分 (41)5.1.2软件部分 (53)5.2 硬件电路板调试实验 (56)5.3本章小结 (59)第六章总结与展望 (61)参考文献 (63)致谢 (66)附录 (67)第一章绪论1.1引言近年来随着电力电子技术的发展,工作在非线性条件下的各种功率器件(电弧炉、电力机车、各种整流装置等)得到了广泛应用,它们在给人类带来巨大利益同时,也把大量的谐波和无功电流注入到电网,造成系统电压、电流波形畸变,效率变低,功率因数变差,并对其他设备和装置产生扰动,给电网环境带来极大的影响,严重威胁电网的电能质量和用户设备的可靠、安全运行。
基于MEMS技术的热导池检测器在变压器油中气体监测系统的应用研究
基于MEMS技术的热导池检测器在变压器油中气体监测系统的应用研究黄德祥1,2,曹建1,2,王会海1,2,丁家峰1,2(1.中南大学物理科学与技术学院,湖南长沙 410083;2.华电云通电力技术有限公司研发部,湖南长沙 410007)[摘要]基于MEMS技术设计的热导池检测器具有重量轻、体积小、成本低、灵敏度高等特点。
本文首先介绍了用于变压器油中气体监测的色谱分析技术及存在的不足,分析了热导池检测器的工作原理和MEMS技术的特点,在此基础上根据实际的需求,设计了一个由基于MEMS技术的TCD构成的变压器油中气体在线监测系统,实验表明,该系统灵敏度、稳定性等均达到了现场检测的需求,能够应用于工业现场。
[关键词]色谱技术;微机电系统;热导池检测器;变压器[中图分类号] TP274+.5[文献标识码] A Application study of thermal conductivity detector based on MEMS for the gas monitoring system oftransformer oilHuang De-xiang1,2, Cao Jian1,2,Wang Hui-hai1,2,Ding Jia-feng1,2(1.College of Physics Science & Technology, Central South University, Changsha 410083, China;2.R&D Office, Huadian Y untong Power Technical Co.,LTD.,Changsha 410007,China)Abstract: The thermal conductivity detector based on MEMS has the advantages of light weight, small size, low cost, high sensitivity. The gas chromatogram technology that is now widely used for gas analysis of transformer oil and its deficiency are introduced in this article. The principle of TCD and the characteristic of MEMS technology are also analyzed. Based on the analysis, a gas monitoring system of transformer oil composed of thermal conductivity detector based on MEMS is designed in————————————————基金项目:国家自然科学基金资助项目(50277039)this article. Experiments indicate that the sensitivity and stability of the system reaches the requirement of detecting and can be used in the industrial locale.Key words:Chromatogram technology; Micro Electro-Mechanical System; Thermal Conductivity Detector; Transformer1 引言变压器是电力系统中十分重要的设备,因此对变压器的运行状态进行监控是保证电网安全运行的关键。
PSCAD例子的学习(对部分example的解释)_New.doc
PSCAD例子的学习(对部分example的解释)PSCAD例子的学习笔记一、黄金分割法(在optimum_run)二、电能质量(在PowerQuality中)软件的英文说明:This application example is based on a case origionally created at the Manitoba HVDC Research Centre by Dr. M. Reformat, in Manitoba, Canada.This case illustrates the use of a STATCOM to provide active filtering for the ac side of a 6-pulse converter system. The Active filter is connected through a 20 kV A, Y-Y transformer to a 200 V, 50 Hz, 3-Phase bus, with a 6-pulse converter loadREFERENCE:H. Fujita and H. Akagi,'A Practical Approach to Harmonic Compensationin Power Systems - Series Connection of Passiveand Active Filters', IEEE Trans. on Ind.Applications,vol.27, No.6, Nov/Dec 1991, pp. 1020-1025Revised by J.E. Nordstrom - September 2000软件的英文说明。
This application example is based on a case origionally created at Manitoba Hydro, in Manitoba Canada.The problem was that farm animals, during winter months, were experiencing a "tingle voltage", due to suspected poor grounding on the local ground grid.Using PSCAD, the engineers were able tosimulate the local system and determine that the grounding problem was at least partially related to ground rod resistance. During the winter months, t he ground conductivity is poor, resulting in a poor connection between the ground rods and earth.While this case is running, you can adjust the ground rod resistance. Notice the change in voltage across the cow!Revised by J.E. Nordstrom - July 2000三、继电保护Case 1:- Two Thevinen Impedance sources connected via one 100km transmission line.(双电源系统通过100km 长度相连)- System voltage is 230kV settable via source equivalents.(230kV)- Simulates two substations connected via one transmission line.(仿真两个变电所之间的传输线路)- Four fault positions for full fault control ahead and behind station relays.(设计了四个故障点)- Two breakers are independently timed controlled. (Default is closed).(两侧的断路器可以通过时间,默认是合上的)-Independent breaker pole tripping is possible. (可以实现分相操作)CASE2:多个故障点。
POWER QUALITY VCFP96M多功能表计说明书
Min/Max Reactive Power, Max Apparent Power), %THD up to 31st Level
Nominal 5A AC (Min-11mA, Max-6A)
45 to 65Hz
Automatic / Manual (Programmable)
8VA Max
Programmable (For energy)
For energy : 0.01k, 0.1k, 1k, 0.01m, 0.1m, 1m (depending upon CT ratio x PT ratio) For Power, Voltage, Current : Auto resolution For Power factor : 0.001
Accuracy
Memory Retention Measuring Parameters
3Ø-3 wire, 3Ø-4 wire, 2Ø-3 wire, 1Ø-2 wire
11 to 300V AC, (Phase to Neutral) 19 to 519V AC (Phase to Phase)
Humidity (non-condensing) Up to 85% RH
MECHANICAL SPECIFICATIONS
Mounting
Panel gms
DIMENSIONS
99
90.5 91.5
TERMINAL CONNECTIONS
NL
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1INTRODUCTIONIn power system, nowadays, there are more and more impactive loads and non-linear loads. At the same time, there are always circuitry faults and switches inevitably. All of them lead the alteration of power voltage ,such as: voltage sag, voltage surge, over voltage, harmonic pollution and transient disturbing[1]-[5]. So the power quality descends. On the other hand, all kinds of transducers, PLC apparatuses and automatic product lines based on computers are largely applied, to enhance the efficiency of power[6]. Those apparatuses are sensitive to the alteration of voltage. The short changing of power quality will lead to great economic loss. The power quality is being paid more and more attentions.Currently, power quality detecting becomes a hotpot both in internal and overseas[7]-[9]. The detecting difficulty is how to detect and classify voltage flicker, transient disturbing and harmonics[8]. The Fourier transform is not suitable to deal with non-stationary signal that is time-variational. The wavelet transform has localization characteristic both in time domain and frequency domain. It is suitable to analyze time-variational non-stationary signal. Using the wavelet transform to detect power quality is rising[10],[11]. Sweldens introduces wavelet transform based on lifting scheme, namely the second generation wavelet[12],[13]. Compared with the first generation wavelet, the second generation wavelet has some superiority. The details are as follows: (1) The constitution of the second generation wavelet is independent on Fourier transform.;(2) It can actualize integral wavelet transform;(3) It can actualize wavelet transform at current position, no additional memory is needed;(4) It has speedy calculate This work is supported by education office of Sichuan (No:2006B073) velocity[12]. This algorithm is suitable to such instances as self- adaptability, non-linear, anomalous sampling and integer to integer transforms[13].This paper introduces the wavelet transform based on lifting scheme to detect power quality. In this paper, the theory of fast lifting wavelet transform is given and the lifting wavelet of Daubechies(9/7) is applied to detect voltage sag , transient disturb and harmonics. Simulations validate that the method display a good detecting performance in both time and frequency domain and can depict the strange characteristics of the signal.2THE FAST LIFTING WAVELET TRANSFORMDaubechies proved that anyone of the first generation wavelet can be lifted at equivalent impact[1]. The lifting scheme decomposes the transform of the first generation wavelet to three steps: split, predict, update, to construct a better new wavelet.2.1The Forward Transform of Lifting WaveletThe forward transform steps of lifting wavelet are shown as figure 1.Fig1.The forward transform of lifting wavelet2.1.1 SplitPower Quality Detecting Based on Fast Lifting Wavelet TransformMin Li1, Guang-pu He1, Xiao-ying Zhang1,Xiao-hong Wu21. Department of Physics & Electrical Information of Leshan Normal University, Leshan 614004,ChinaE-mail: cassie_li@2. School of Electrical and Information Engineering of Jiangsu University, Zhenjiang 212013ˈChinaE-mail: wxh_www@Abstract: This paper advances a novel method for power quality detection by using fast lifting wavelet transform and utilizing the reconstructed signal to compensate for the harmonics. After the disturbed signal is decomposed to many sub-bands in frequency domain, the disturbing time and level can be identified and the disturbed signal can be compensated by the reconstructed signal. In this paper, the theory of fast lifting wavelet transform is given and the lifting wavelet of Daubechies(9/7) is applied to detect voltage sag, transient disturb and harmonics. Simulations validate that the method display a good detecting performance in both time and frequency domain and can depict the strange characteristics of the signal. Compared to traditional wavelet transform, the lifting wavelet transform depresses calculation complexity, effectively reducing calculation time and no additional memory is required, thus it is more practicability.Key Words:Harmonic analysis, Lifting scheme, Power quality, Wavelet transform.536978-1-4244-1734-6/08/$25.00c 2008IEEEThis step is to decompose the original series o λ into two subsets 1−λ and 1−γ .They have no repeat. Commonly, there is the maximum pertinence between neighboring the data, so we can sample at the interval of parity, namely:(1)2.1.2 Predict This step is to predict1−γ from 1−λ, using the correlationamong data. The predict algorithm is: )(11−−=λγP , which is independent of0λ.Because 1−γ can be predicted by 1−λ, we can use 1−λ to substitute the original data. 1−γ is coefficients of wavelet transform.. We can use the error between 1−γ and the predictable value of 1−λto replace 1−γ. On condition that the prediction is reasonable, the error data comprises less information than original 1−γ.Prediction equation is: )(111−−−−=λγγPHere, the coefficients of wavelet transform 1−γindicates error introduced by algorithm P. We can use less series1−λand 1−γto replace original data. On condition that a prediction is excellent, two subclasses {}11,−−γλ will bemore compact than the original series. This algorithm canbe repeated periodically. For example, we can draw2−λand 2−γout from 1−λ,replacing 2−γby the error between 2−γand )(2−λP . Thus, repeating n steps, we can use {}12,,....,−−−−γγγλn n to replace the original data. {}12,,....,−−−−γγγλn n is more compact than the original data. 2.1.3 UpdateThe subclasses that are produced by split step are not accordant with the original data completely. Such as average value. This step is to find a measurement standard o( ).Under this standard:)()(01λλo o =−.In order to replace 1−λ with 1−γ that is already obtained, we construct analgorithm U and operate as follow:)(111−−−+=γλλU . Repeating it, the low frequency series are decomposed recursively. The multi-analysis wavelet transform equation is as bellow:(2)2.2 The Inverse Transform of Lifting WaveletToward lifting schemes, we can immediately obtain the inverse transform after forward transform. The only thingwe have to do is interchanging plus signs and subtraction signs. This is one excellent characteristic of lifting schemes. The reconstruction course is the contrary course of decomposition, shown as figure 2.Fig2.The inverse transform of lifting waveletThe inverse transform equation is:(3)The key of lifting scheme is to find an effective predictionfunction and an updating function. Daubechies andSweldens bear out that any digital wavelet transformhaving limited length filter can be lifted by factoring itspoly-phase matrix. For lifting schemes, the predictionalgorithm and updating algorithm can be linear ornon-linear.2.3 The Lifting Wavelet of Daubechies(9/7)This paper uses the lifting wavelet of Daubecheis(9/7) to analyze power quality. This wavelet transform needs twosteps of prediction and two steps of updating. They are inseries, as figure 3.Fig3.The lifting structure of Daubechies(9/7)The detailed steps as follow:Step1:)]22()2([)12()12(++×++=+n s n s n s n c α; Step2:)]12()12([)2()2(++−×+=n c n c n s n d β; Step3:)]22()2([)12()12(++×++=+n d n d n c n c γ;2008Chinese Control and Decision Conference (CCDC 2008)537Step4:)]12()12([)2()2(++−×+=n c n c n d n d δ; Step5:)12()12(+×=+n c h n c)2()/1()2(n d h n d ×=The fore four steps are lifting course. The last step is to standardize coefficients. The parameters’ values are as bellow:230174105.1443506852.0;882911075.0052980118.0;586134342.1===−=−=h δγβα3 SIMULATIONS OF POWER QUALITY DETECTING In this paper, the lifting wavelet of Daubechies(9/7) is applied to detect voltage sag , transient disturb and harmonics.3.1 The Detecting of Voltage Sag Voltage sag is that voltage’s virtual value decreases to 0.1~0.9 p.u of rated value, and continuances 10ms~1min,then resumes the normal value. It usually results from induction-motors start-up, short circle faults, on-off operations and transformers’ or capacitors’ switch. While the main causations of voltage sag are the former two. To father voltage sag, first of all, we should measure accurately the beginning time and the ending time of which. A signal of voltage sag is given as figure 4(a). The voltage descends 50%,and continues 3 periods. The sampling frequency is 4KHz. This paper chooses the lifting wavelet of Daubechies(9/7) to decompose the signal at level 6. The coefficients of details at level 1 are shown asfigure4(b).From which, we can obtain the beginning timeand the ending time of voltage sag accurately.Fig4.Detecting results of voltage sag3.2 The Detecting of Voltage Transient PulseThe signal that simulates voltage transient pulse is shown as figure 5(a). It is a sine wave lasting for two periods Disturbed by transient pulse at a certain moment. The sampling frequency is 4KHz. This paper introduces the lifting wavelet of Daubechies(9/7) to detect the disturbing time. The disturbed signal is decomposed at level 6.The coefficients of details at level 1 are shown as figures 5(b). From which, the oddity point and its time are obtainedclearly.Fig5..Detecting results of voltage transient pulse3.3 The Detecting of Voltage Transient SurgeA sine signal disturbed by transient surge is shown as figure6(a).This paper uses the same lifting wavelet of Daubechies(9/7) to decompose the original signal at level 6.The coefficients of details at level 1 shown as figure 6(b)give out the accurate time when surge begins and attenuates. Also, we can obtain the surge frequency boundfrom decomposed sub-bands of frequency.Fig6..Detecting results of voltage transient surge 3.4 Harmonic Detecting Along with the wide application of vast non-linear wirings, the harmonic pollution becomes more and more serious. The content of harmonics becomes one of the most important guide line to scale power quality. Accurate harmonic detection is the precondition to control and eliminate harmonics. The fast lifting wavelet transform can detect the first-harmonic wave and the total freakish currency accurately and fleetly. Then, it can compensate the first-harmonic wave by using the total freakish currency. The harmonics of power system are usually odd harmonics. The simulation signal is shown as figure 7.Its mathematicexpression is:The first-harmonic wave of original signal is as figure 8.There are different sub-bands of frequency after the original signal decomposed by the lifting wavelet of Daubechies(9/7) at level 4.We obtain the total freakish currency by choosing coefficients of details at all levels to reconstruct. The total freakish currency is shown as figure 9.Then, we obtain the first harmonic wave by using the total freakish signal to compensate original signal. The5382008Chinese Control and Decision Conference (CCDC 2008)compensated first harmonic wave is shown as figure 10,which is similar to the original one. But there are stillerrors, which are shown as figure 11.Fig7.The original signalFig8. First harmonic wave of original signalFig9. Reconstructed total harmonic signalFig10. Compensated first harmonic waveFig11. Inaccuracy of compensated first harmonic wave 4 CONCLUSIONS Above analysis indicates that the lifting wavelet ofDaubechies(9/7) can detect transient disturbing signal ofpower system accurately. It is sensitive to the bizarrevariety of signals, so it can score the time accurately when bizarre variety occurs. In the domain of harmonic detecting,it can measure the total aberrance and compensate the firstharmonic. The detecting is more accurate than the firstgeneration wavelet transform. Because of its particular structure, the lifting wavelet has simple algorithm and no additional memory is needed. It is easy to be realized by hardware. Above all, the lifting wavelet of Daubechies(9/7) is a fast and effective method to detect power quality. The next work is to turn it into realization with hardware.REFERENCES [1] Popescu M, Bitoleanu A, Dobriceanu M. “Power qualityassessment via Matlab/Simulink-based tool”, 7th IASTD International Conference on Power and Energy Systems, 163-168, 2007.[2] Leccese F, “Rome: A first example of perceived powerquality of electrical energy”, 7th IASTD InternationalConference on Power and Energy Systems, 169-176, 2007. 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[9] Maly J, Rajmic P 㧘 “Fast lifting wavelet transform and itsimplementation in Java”, 12th International Conference on Personal Wireless Communications (PWC 2007), 245:488-496, 2007.[10] Li W, Zhu XF, Wu SC, “A novel approach to fast medicalimage fusion based on lifting wavelet transform”, 6th World Congress on Intelligent Control and Automation, Vols 1-12, Conference Poceedings : 9881-9884, 2006 .[11] Fan WB, Chen J, Zhen JN, “SPIHT algorithm based on fastlifting wavelet transform in image compression”,International Conference on Computational Intelligence and Security, pt 2, Proceedings 3802: 838-844, 2005 .[12] Xiong CY, Tian JW, Liu H, “a fast VLSI architecture fortwo-dimensional discrete wavelet transform based on liftingscheme”, 7th International Conference on Solid-State and Integrated Circuits Technology, vols 1- 3, Proceedings : 1661-1664, 2004 .[13] Li ZM, Wei PY, Yin LJ, et al. “The remote monitoring andanalysis system of power quality”, General System andControl System, Vol i : 189-192, 2007.[14] de la Rosa JJG, Luque A, Munoz AM, “Higher-orderstatistics interpretation. Application to power-qualitycharacterization”, Proceedings of the Second International Conference on Signal Processing and Multimedia Applications : 72-78, 2007.[15] Hu GS, Zhu FF, Zhang YZ, “Power quality faint disturbance identification using wavelet packet energy entropy and weighted support vector machines”, Third InternationalConference on Natural Computation, vol 5, Proceedings : 649-653, 2007.[16] Zhang J, Romano E, Mazzola J. “High quality uniform SiCepitaxy for power device applications”, Silicon Carbide and Related Materials 2006 556-557: 101-104, 2007 .2008Chinese Control and Decision Conference (CCDC 2008)539[17] Leonowicz Z, “New power quality indices”, Proceedings ofThe Seventh Iasted International Conference on Power and Energy Systems : 157-162, 2007 .[18] Arvindan AN, Sharma VK, “Current control of a high powerfactor improved power quality four quadrant AC-DCconverter”, IEEE International Conference on IndustrialTechnology Symposium, VOLS 1-6 : 1765-1770,2006. [19] Bhat AH, Agarwal P, “A comparative evaluation ofthree-phase high power factor boost converters for powerquality improvement”, IEEE International Conference onIndustrial Technology Symposium, VOLS 1-6 : 86-91, 2006.[20] Crapse P, Wang JJ, Abrams J. “Power quality assessmentand management in an electric ship power system”, 2007IEEE Electric Ship Technologies Symposium (ESTS 2007) : 328-334, 2007. [21] Steurer M, Andrus M, Langston J. “Investigating theimpact of pulsed power charging demands onshipboard power quality”, 2007 IEEE Electric ShipTechnologies Symposium: 315-321, 2007 . GRAPHIESMin L I was born in Sichuan, China, on August 10, 1977. She received the M.Sc degree in mechanical and electrical engineering from Xihua University, China, in 2003 .Now, she is a lecture in department of physics and electron communication of L eshan teachers college. Her special fields of interest includes signal processing ,wavelet analysis and power quality detecting.5402008Chinese Control and Decision Conference(CCDC2008)。