公开(公告)号：US5832414A

公开(公告)日：1998-11-03

申请号：US939932

申请日：1997-09-29

申请人： David G. Hart ,  James D. Stoupis ,  Damir Novosel

发明人： David G. Hart ,  James D. Stoupis ,  Damir Novosel

IPC分类号： G01R19/25 ,  G01R23/00 ,  G01R23/16 ,  G01R23/10

CPC分类号： G01R19/2513 ,  G01R23/16 ,  G01R23/00

摘要： A new method of compensating for errors in phasor estimation due to oscillations caused by discrete fourier transforms used to estimate signal frequency is provided. The method uses a variable N-point DFT to compute one or more phasors based on data acquired from one or more sampled signals. At each sampling interval the change in phasor angle between the current sampling interval and the previous sampling interval is determined and used to estimate the instantaneous frequency of the signal. A non-oscillating phasor indicative of the instantaneous magnitude, angular frequency, and phase angle of the signal is generated based on the instantaneous frequency estimate. Instantaneous frequencies are averaged over a cycle of the signal to generate an average cycle frequency. In addition, a number of discrete frequencies and corresponding DFT windows based on a fixed sampling rate and a predetermined fundamental frequency of the signal are defined and used in estimating the instantaneous frequency. The DFT window is adjusted by setting it equal to the DFT window corresponding to the discrete frequency closest to the average cycle frequency. A generator protection system analyzing voltage and current signals output from a generator is also provided. The voltage and current signals are monitored by respective voltage and current sensors to produce a plurality of signals representative of voltage and current characteristics of the generator. The system comprises components for receiving and sampling signal input, and for processing the samples according to the inventive method.

摘要翻译： 提供了一种补偿由于用于估计信号频率的离散傅立叶变换引起的振荡引起的相量估计误差的新方法。 该方法使用可变N点DFT来基于从一个或多个采样信号获取的数据来计算一个或多个相量。 在每个采样间隔，确定当前采样间隔和先前采样间隔之间的相量角的变化，并用于估计信号的瞬时频率。 基于瞬时频率估计产生指示信号的瞬时幅度，角频率和相位角的非振荡相量。 瞬时频率在信号的周期上平均以产生平均周期频率。 另外，基于固定采样率和信号的预定基频定义了多个离散频率和相应的DFT窗口，并用于估计瞬时频率。 通过将DFT窗口设置为与最接近平均周期频率的离散频率对应的DFT窗口进行调整。 还提供了分析从发电机输出的电压和电流信号的发电机保护系统。 电压和电流信号由相应的电压和电流传感器监测，以产生代表发电机的电压和电流特性的多个信号。 该系统包括用于接收和采样信号输入的组件，并且用于根据本发明的方法处理样本。

公开(公告)号：US06397156B1

公开(公告)日：2002-05-28

申请号：US09192851

申请日：1998-11-17

申请人： Bernhard Bachmann ,  David G. Hart ,  Yi Hu ,  Damir Novosel ,  Murari M. Saha

发明人： Bernhard Bachmann ,  David G. Hart ,  Yi Hu ,  Damir Novosel ,  Murari M. Saha

IPC分类号： G01R2500

CPC分类号： H02H3/40 ,  H02H1/04

摘要： An accurate impedance measurement method for a power system transmission line is disclosed for improving various protection functions, i.e., distance protection and/or fault location estimation. The method is less sensitive to harmonics and other transient problems introduced to power systems by series capacitance and the like, and is easily incorporated into existing protective relays. In the method, a number (n) of current and voltage samples (Ik, Vk) representative of values of current and voltage waveforms are measured, respectively, at successive instants of time on a conductor in a power system. The number n is an integer greater than I and the index k takes on values of 1 to n. Resistance (R) and inductance (L) values are computed in accordance with an equation in which R and L are related to sums of differences in values of successive current and voltage samples. A prescribed power system function is then performed based on the computed R and L values.

摘要翻译： 公开了一种用于电力系统传输线路的精确阻抗测量方法，用于改进各种保护功能，即距离保护和/或故障位置估计。 该方法对通过串联电容等引入电力系统的谐波和其他瞬态问题较不敏感，并且容易地并入现有的保护继电器中。 在该方法中，分别在电力系统中的导体上的连续时刻分别测量表示电流和电压波形值的电流和电压样本数（Ik，Vk）的数量（n）。 数字n是大于I的整数，索引k取值为1到n。 电阻（R）和电感（L）值根据其中R和L与连续电流和电压样本的值的差的和相关的方程式来计算。 然后根据计算的R和L值执行规定的电力系统功能。

公开(公告)号：US06584417B1

公开(公告)日：2003-06-24

申请号：US09425661

申请日：1999-10-22

申请人： Yi Hu ,  Damir Novosel ,  David G. Hart

发明人： Yi Hu ,  Damir Novosel ,  David G. Hart

IPC分类号： G01R3108

CPC分类号： G01R31/085 ,  H02H3/081 ,  H02H3/405

摘要： An electrical power system includes a transmission line for transmitting electrical power, series capacitance compensation series-coupled to the transmission line adjacent one end thereof, where the series compensation includes a capacitance having a value (−j XCAP), and a protective relay at the one end of the transmission line for monitoring line voltages and line currents on the transmission line. Upon sensing a fault, an impedance Z of the line is calculated based on the monitored line voltages and line currents. The calculated impedance Z is adjusted according to the value of the capacitance of the series compensation (−j XCAP) to result in a modified impedance ZMOD, and the phasor angle Of ZMOD is examined to determine the direction of the sensed fault. The fault is in a first direction if the phasor angle is between X and X+180 degrees and is in a second direction opposite the first direction if the phasor angle is between X+180 and X+360 degrees.

摘要翻译： 电力系统包括用于发送电力的传输线，串联耦合到其一端附近的传输线的串联电容补偿，其中串联补偿包括具有值（-j XCAP）的电容，以及保护继电器 传输线的一端用于监测传输线上的线路电压和线路电流。 在检测到故障时，根据被监测的线路电压和线路电流计算线路的阻抗Z。 根据串联补偿（-j XCAP）的电容值调整计算阻抗Z，得到修正的阻抗ZMOD，并检查ZMOD的相量角以确定感测故障的方向。 如果相量角在X和X + 180度之间，并且如果相量角在X + 180和X + 360度之间，并且处于与第一方向相反的第二方向，则故障处于第一方向。

公开(公告)号：US06173216B2

公开(公告)日：2001-01-09

申请号：US09060508

申请日：1998-04-15

申请人： Khoi Vu ,  David G. Hart ,  Damir Novosel

发明人： Khoi Vu ,  David G. Hart ,  Damir Novosel

IPC分类号： H02J114

CPC分类号： H02H1/0092 ,  G01R19/2513

摘要： As a variation of the non-orthogonal filter, a phasor estimate is computed by using an N-point window. An aspect of the sub-window cosine filter is to repeat the basic cosine filter for only selected points of the window. In the end, a least-squares fit is used to obtain an estimate for the phasors components. Previous cosine techniques use a data window whose length is greater than 1 cycle while the present invention requires only 1 cycle.

摘要翻译： 作为非正交滤波器的变型，通过使用N点窗口来计算相量估计。 子窗口余弦滤波器的一个方面是仅对窗口的选定点重复基本余弦滤波器。 最后，使用最小二乘拟合来获得相量分量的估计。 以前的余弦技术使用长度大于1周期的数据窗口，而本发明仅需要1个周期。

公开(公告)号：US6154687A

公开(公告)日：2000-11-28

申请号：US60458

申请日：1998-04-15

申请人： David G. Hart ,  Damir Novosel ,  Robert A. Smith

发明人： David G. Hart ,  Damir Novosel ,  Robert A. Smith

IPC分类号： G01R19/25 ,  H02H3/38 ,  H02J1/14 ,  H02H7/00 ,  H02H9/00 ,  H02J3/02 ,  H02J17/00

CPC分类号： G01R19/2513 ,  H02H3/38

摘要： A high sample rate cosine filter eliminates DC components by summing them such that they sum to zero. A non-orthogonal cosine filter is also provided. When the cosine filter is applied for N=4 samples per cycle, the samples are separated by 90 degrees. However, at higher sampling rates, it is not necessary to wait for 90 degrees to estimate the phasor value. Non-orthogonal components are used to estimate the phasor value. The time delay associated with the cosine filter is reduced in the process.

摘要翻译： 高采样率余弦滤波器通过将它们相加来消除DC分量，使得它们总和为零。 还提供了非正交余弦滤波器。 当每个循环使用余弦滤波器N = 4个样本时，样本被分离90度。 然而，在更高的采样率下，不需要等待90度来估计相量值。 非正交分量用于估计相量值。 与余弦滤波器相关的时间延迟在该过程中减少。

公开(公告)号：US06453248B1

公开(公告)日：2002-09-17

申请号：US09119792

申请日：1998-07-21

申请人： David G. Hart ,  Damir Novosel ,  Steven A. Kunsman

发明人： David G. Hart ,  Damir Novosel ,  Steven A. Kunsman

IPC分类号： G01R3100

CPC分类号： G01R31/088 ,  G01R31/085 ,  G01R31/086 ,  H02H1/0015 ,  Y04S10/522

摘要： An improved high impedance fault (HIF) detection system comprises an analyzer located at a circuit breaker or substation with feeders, wherein the analyzer analyzes current and/or voltage waveforms to detect a HIF on the feeder or on one of a plurality of laterals coupled to the feeder; a plurality of remote outage detectors located respectively at corresponding customer sites, each remote outage detector including a mechanism to detect a loss of potential or power at the corresponding site; and a computer in communication with the analyzer and the remote outage detectors.

摘要翻译： 改进的高阻抗故障（HIF）检测系统包括位于具有馈线的断路器或变电站的分析仪，其中分析器分析电流和/或电压波形，以检测馈线上的HIF或多个耦合到 进料器; 分别位于相应的客户位置的多个远程停机检测器，每个远程停电检测器包括用于检测对应站点的电位或电力损失的机构; 以及与分析仪和远程停机检测器通信的计算机。

公开(公告)号：US06336059B1

公开(公告)日：2002-01-01

申请号：US09192956

申请日：1998-11-17

申请人： Damir Novosel ,  Bernhard Bachmann ,  Yi Hu ,  David G. Hart ,  Murari M. Saha

发明人： Damir Novosel ,  Bernhard Bachmann ,  Yi Hu ,  David G. Hart ,  Murari M. Saha

IPC分类号： G05B1900

CPC分类号： H02H3/40

摘要： A reach-measurement method is used in connection with a series-compensated line of a power system. The series-compensated line includes an installed series capacitance having a bus side and a line side, and a non-linear protection device parallel to the installed series capacitance. The series-compensated line has a line current, a bus side voltage, and a line side voltage. The series capacitance and the non-linear protection device have a capacitance voltage thereacross equal to the bus side voltage minus the line side voltage. In the method, a number (n) of line current samples are measured, where such samples are representative of values of a line current waveform at successive instants of time on the series-compensated line. Capacitance voltage values are computed based on the measured line current samples in accordance with an equation which takes into account the non-linear protection device parallel to the installed series capacitance. A prescribed power system function is then performed based on the computed capacitance voltage values.

摘要翻译： 与电力系统的串联补偿线结合使用到达测量方法。 串联补偿线包括具有总线侧和线路侧的安装的串联电容以及与安装的串联电容并联的非线性保护装置。 串联补偿线路具有线路电流，总线侧电压和线路侧电压。 串联电容和非线性保护装置的电容电压与母线侧电压减去线路侧电压相等。 在该方法中，测量线数电流样本数（n），其中这些采样代表串联补偿线上连续时刻的线电流波形的值。 电容电压值是根据测得的线路电流样本根据考虑到与安装的串联电容平行的非线性保护装置的方程计算的。 然后基于计算的电容电压值执行规定的电力系统功能。

公开(公告)号：US06738719B2

公开(公告)日：2004-05-18

申请号：US09951925

申请日：2001-09-13

申请人： James D. Stoupis ,  David Lubkeman ,  Reto Buettner ,  David G. Hart

发明人： James D. Stoupis ,  David Lubkeman ,  Reto Buettner ,  David G. Hart

IPC分类号： G01R3100

CPC分类号： H02H1/00 ,  H02H3/385 ,  H02H7/267

摘要： The invention describes a method, system, device, and computer-readable medium having computer-executable instructions for classifying faults on an electrical power line. In particular, the invention permits the classification of crossover faults, using a local measurement technique. The inventive method includes providing a first electrical power transmission line and a second electrical power transmission line, and monitoring the first electrical power transmission line to identify a crossover fault occurring between the first and the second electrical power transmission lines.

公开(公告)号：US6081768A

公开(公告)日：2000-06-27

申请号：US929927

申请日：1997-09-15

申请人： Yi Hu ,  David G. Hart ,  Joseph P. Benco ,  James D. Stoupis

发明人： Yi Hu ,  David G. Hart ,  Joseph P. Benco ,  James D. Stoupis

IPC分类号： G01R19/04 ,  H02H7/04 ,  H02H3/00

CPC分类号： G01R19/04 ,  H02H7/04

摘要： A method and system for detecting the peak of respective half-cycles of a sinusoidal waveform. The sinusoidal waveform is rectified and only sample points above a first threshold are analyzed. The peaks of each half-cycle are only accepted if they are above a second, greater threshold. Peaks below the second threshold are not accepted. The peaks themselves are detected by starting a counter at the first sample in the rectified waveform which is above the first threshold value. Once the rectified waveform descends below the first threshold, the counter is stopped and the maximum value of the previous k samples is the peak value, where k is the counter value for the successive samples above the first threshold. The peak value so determined is rejected if it is less than the second threshold value. On the other hand, when the peak value is above the second threshold, it is averaged with the last valid peak value (above the second threshold). Thus, the V/Hz value remains the same until a new, valid peak is determined. A preferred embodiment implements such a digital peak detector in a digital relay system for detecting overexcitation of a power system.

摘要翻译： 用于检测正弦波形的各个半周期的峰值的方法和系统。 正弦波形被整流，并且仅分析高于第一阈值的采样点。 每个半周期的峰值只有在高于第二个较大的阈值时才被接受。 低于第二个阈值的峰值不被接受。 通过在高于第一阈值的整流波形中的第一采样处启动计数器来检测峰值本身。 一旦整流波形下降到第一阈值以下，则停止计数器，并且先前k个采样的最大值是峰值，其中k是高于第一阈值的连续采样的计数器值。 如果确定的峰值小于第二阈值，则其被拒绝。 另一方面，当峰值高于第二阈值时，用最后的有效峰值（高于第二阈值）进行平均。 因此，在确定新的有效峰值之前，V / Hz值保持不变。 优选实施例在数字中继系统中实现这种数字峰值检测器，用于检测电力系统的过激励。

公开(公告)号：US06185482B2

公开(公告)日：2001-02-06

申请号：US09037359

申请日：1998-03-10

申请人： Michael Egolf ,  David G. Hart ,  James D. Stoupis

发明人： Michael Egolf ,  David G. Hart ,  James D. Stoupis

IPC分类号： H02J114

CPC分类号： H02H3/05 ,  H02H7/06

摘要： A method and apparatus for over current backup protection is provided. The method generates a set of root mean square (rms) values from samples that are taken from the system current. Several rms current values are averaged to generate an estimated rms over current value. The estimated over current value is compared with a predetermined threshold value. If the estimated current is above the predetermined threshold value, a fault protection mechanism, such as opening a circuit breaker, is activated. A generator protection unit having digital signal processing capabilities executes the inventive method to provide protection from over current episodes.

摘要翻译： 提供了一种用于过流备份保护的方法和装置。 该方法从从系统电流获取的样本中生成一组均方根（rms）值。 将几个均方根电流值平均以产生超过电流值的估计有效值。 将估计的过电流值与预定阈值进行比较。 如果估计电流高于预定阈值，则启动诸如断路器之类的故障保护机构。 具有数字信号处理能力的发生器保护单元执行本发明的方法以提供对过去电流的保护。