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：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：US5839093A

公开(公告)日：1998-11-17

申请号：US777623

申请日：1996-12-31

申请人： Damir Novosel ,  David Hart ,  Yi Hu ,  Jorma Myllymaki

发明人： Damir Novosel ,  David Hart ,  Yi Hu ,  Jorma Myllymaki

IPC分类号： G01R31/08 ,  H02H3/26

CPC分类号： G01R31/086

摘要： Both fault location and fault resistance of a fault are calculated by the present method and system. The method and system takes into account the effects of fault resistance and load flow, thereby calculating fault resistance by taking into consideration the current flowing through the distribution network as well as the effect of fault impedance. A direct method calculates fault location and fault resistance directly while an iterative fashion method utilizes simpler calculations in an iterative fashion which first assumes that the phase angle of the current distribution factor D.sub.s is zero, calculates an estimate of fault location utilizing this assumption, and then iteratively calculates a new value of the phase angle .beta..sub.s of the current distribution factor D.sub.s and fault location m until a sufficiently accurate determination of fault location is ascertained. Fault resistance is then calculated based upon the calculated fault location. The techniques are equally applicable to a three-phase system once fault type is identified.

摘要翻译： 通过本方法和系统计算故障位置和故障故障电阻。 该方法和系统考虑了故障电阻和负载流量的影响，从而通过考虑流经配电网络的电流以及故障阻抗的影响来计算故障电阻。 直接方法直接计算故障位置和故障电阻，而迭代方法以迭代方式利用更简单的计算，首先假设电流分布因子Ds的相位角为零，使用该假设计算故障位置的估计，然后 迭代地计算当前分布因子Ds和故障位置m的相位角βs的新值，直到确定故障位置的足够精确的确定。 然后根据计算出的故障位置计算故障电阻。 一旦发现故障类型，这些技术同样适用于三相系统。

公开(公告)号：US5671112A

公开(公告)日：1997-09-23

申请号：US647589

申请日：1996-05-13

申请人： Yi Hu ,  David Hart ,  Damir Novosel ,  Robert Smith

发明人： Yi Hu ,  David Hart ,  Damir Novosel ,  Robert Smith

IPC分类号： G01R19/04 ,  H02H7/04 ,  H02H3/18

CPC分类号： H02H7/04 ,  G01R19/04

摘要： A system for implementing accurate V/Hz value measurement and trip time determination for generator/transformer overexcitation protection independent of the conventional frequency tracking and phasor estimation based on Discrete Fourier Transformation (DFT) techniques. A sampled sinusoidal voltage signal is passed through a digital integrator and the magnitude of the digital integrator's output is measured as representative of the V/Hz ratio. The digital integrator is implemented in software using a difference equation in a generator protection unit. The technique may be used with either a fixed or a variable sampling frequency. When the sampling frequency is variable, the filter coefficients of the digital integrator are recalculated on-line each time the sampling frequency is changed, and a new value for the peak magnitude of the output of the digital integrator is calculated using the recalculated filter coefficients. Non-linear frequency response characteristics of the voltage sensors and non-ideal characteristics of the digital integrator are also adjusted using the measured frequency and error-frequency characteristics of the particular digital integrator and voltage sensors used.

摘要翻译： 一种用于实现发电机/变压器过励磁保护的精确V / Hz值测量和跳闸时间确定的系统，与传统的基于离散傅里叶变换（DFT）技术的频率跟踪和相量估计无关。 采样的正弦电压信号通过数字积分器，并且数字积分器的输出的幅度被测量为代表V / Hz比。 数字积分器采用发电机保护单元中的差分方程软件实现。 该技术可以与固定或可变采样频率一起使用。 当采样频率可变时，每次采样频率改变时，数字积分器的滤波器系数在线重新计算，并且使用重新计算的滤波器系数计算数字积分器的输出的峰值幅度的新值。 电压传感器的非线性频率响应特性和数字积分器的非理想特性也使用所使用的特定数字积分器和电压传感器的测量频率和误差频率特性进行调整。

公开(公告)号：US5956220A

公开(公告)日：1999-09-21

申请号：US19321

申请日：1998-02-05

申请人： Damir Novosel ,  Yi Hu ,  Murari M. Saha

发明人： Damir Novosel ,  Yi Hu ,  Murari M. Saha

IPC分类号： H02H3/40 ,  H02H7/26 ,  H02H3/00

CPC分类号： H02H7/267 ,  H02H3/40

摘要： An adaptive distance relaying system provides improved performance for parallel circuit distance protection. The system utilizes the parallel circuit's current, when available, in conjunction with measurements of voltage and current on the protected line to compensate for the zero sequence current mutual coupling effect. The sequence current ratio (zero or negative sequence) is used to avoid incorrect compensation for relays on the healthy circuit. If the parallel circuit current is not available and the line operating status is, the best zero sequence current compensation factors are selected accordingly as a next level adaptation. If both the parallel circuit current and line operating status are unavailable, a fallback scheme that offers better results than classical distance protection schemes is employed.

摘要翻译： 自适应距离中继系统为并联电路距离保护提供了改进的性能。 该系统在可用时利用并联电路的电流与受保护线路上的电压和电流的测量结合，以补偿零序电流互耦效应。 顺序电流比（零或负序）用于避免健康电路上继电器的不正确补偿。 如果并联电路电流不可用并且线路运行状态是，则最佳的零序电流补偿因子被相应地选择为下一级适配。 如果并联电路电流和线路运行状态都不可用，则采用比传统距离保护方案更好的结果的回退方案。

公开(公告)号：US5805395A

公开(公告)日：1998-09-08

申请号：US766715

申请日：1996-12-13

申请人： Yi Hu ,  David Hart ,  Damir Novosel ,  Robert Smith

发明人： Yi Hu ,  David Hart ,  Damir Novosel ,  Robert Smith

IPC分类号： H02H7/04 ,  H02H7/06

CPC分类号： H02H7/04 ,  H02H7/06

摘要： A system for implementing accurate V/Hz value measurement and trip time determination for generator/transformer overexcitation protection independent of the conventional frequency tracking and phasor estimation based on Discrete Fourier Transformation (DFT) techniques. The half-cycle summation technique of the invention is a non-recursive digital technique which measures the per unit V/Hz value by summing the sampled data points in every half cycle of a sinusoidal input signal and dividing the sum with the ideal base sum value. When the input voltage signal is sampled at a reasonable frequency, the technique of the invention approximates the accurate per unit V/Hz value of the input voltage signal and thus obtains an accurate V/Hz characteristic directly without computing voltage and frequency separately.

摘要翻译： 一种用于实现发电机/变压器过励磁保护的精确V / Hz值测量和跳闸时间确定的系统，与传统的基于离散傅里叶变换（DFT）技术的频率跟踪和相量估计无关。 本发明的半周期求和技术是一种非递归数字技术，其通过将正弦输入信号的每半个周期中的采样数据点相加并且将和除以理想基本和值来测量每单位V / Hz值 。 当以合理的频率对输入电压信号进行采样时，本发明的技术近似于输入电压信号的每单位V / Hz值的准确度，从而直接获得精确的V / Hz特性，而不分别计算电压和频率。

公开(公告)号：US5721689A

公开(公告)日：1998-02-24

申请号：US574357

申请日：1995-12-18

申请人： David Hart ,  Yi Hu ,  Damir Novosel ,  Robert Smith

发明人： David Hart ,  Yi Hu ,  Damir Novosel ,  Robert Smith

IPC分类号： G01R19/25 ,  G01R23/00 ,  G01R23/16 ,  G01R23/10 ,  H03M1/00

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

摘要： A method and system for estimating phasors and tracking the frequency of a signal 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. Instantaneous frequencies are averaged over a cycle of the signal. 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. Once the average cycle frequency is determined the DFT window is adjusted by setting it equal to the DFT window corresponding to the discrete frequency closest to the average cycle frequency.

摘要翻译： 提供了一种用于估计相量并跟踪信号频率的方法和系统。 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。 瞬时频率在信号的周期上平均。 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。 一旦确定平均周期频率，则通过将DFT窗口设置为等于最接近平均周期频率的离散频率的DFT窗口来调整DFT窗口。

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：US06747373B1

公开(公告)日：2004-06-08

申请号：US10034063

申请日：2001-12-26

申请人： Yi Hu ,  Luciano Di Maio ,  Fabio Gatelli ,  William M. Egolf ,  David G. Hart

发明人： Yi Hu ,  Luciano Di Maio ,  Fabio Gatelli ,  William M. Egolf ,  David G. Hart

IPC分类号： G05F300

CPC分类号： H02M1/12 ,  Y10T307/826

摘要： System and methods for coordinating the control system of a switched power capacitor with an integrated resonance protection function. The coordination system coordinates the function of a switched power capacitor's primary control system and resonance protection system to avoid duplication of tasks and on/off operation deadlock. The coordination system adjusting calculations made by the primary control system in response to a determination of a harmonic resonance condition by the resonance protection system.

摘要翻译： 用于协调具有集成谐振保护功能的开关式电力电容器的控制系统的系统和方法。 协调系统协调开关电源电容器的主控制系统和共振保护系统的功能，以避免重复任务和开/关操作死锁。 协调系统根据由谐振保护系统确定的谐波共振状态来调整主控系统进行的计算。