A Method of Deriving Overall Accuracy for Single Phase Watthour Meters

The ANSI Standard equation for overall accuracy places a small amount of emphasis on light load accuracy for watthour meters. Results from a recent load research study indicated a significant amount of energy is accumulated at lighter loads where watthour meter accuracy is poorer. Perhaps the standard equation for overall accuracy is a consensus of opinions prior to utilities performing load research studies. Although small inaccuracies of watthour meters at lighter loads may seem insignificant, they become large when applied to an entire meter population. ANSI C12.1-1982 may be interpreted to mean that 20% of all energy registration occurs at light load. The results of a load research study show that watthour meters spend a great deal of time at light loads. A method was developed to establish at which loads watthour meters register energy consumption. Watthour meters spent 85% of the time and registered more than 40% of the total energy for a one year period at light loads.     

A watt-hour meter-the solid state polyphase kind

The old watt-hour revenue meter with its rotating disc is a familiar sight at every electric service entrance, be it residential, industrial, or commercial. However, modern technology has made a solid state version economical for most new polyphase metering installations. Polyphase metering is the norm for all industrial and many commercial consumers. This is because the large power levels and polyphase motors in use require polyphase electric service. New polyphase metering installations now favour solid state meters use because of their economically advantageous versatility and accuracy. In contrast, new single phase meters, the sort seen on all our homes, will probably continue to be electromechanical for some time. This is despite the fact solid state equivalents are available. Solid state single phase meters are being installed in England, however. This article describes how a typical solid state meter, in particular General Electric's Phase3 Electronic Meter, determines energy consumption. Also how it provides many more functions than electromechanical meters     

Series-parallel versus true polyphase calibration of electricitymeters

This paper describes a study of single-phase-series-parallel versus polyphase calibration of electricity meters. Historically there has been some debate regarding the field performance of electromechanical electricity meters that have been calibrated using the series-parallel technique which is common in North America and other areas. A methodology was carefully established that would allow several meter testing laboratories to be verified and traceable to each other. Meters were tested and the data is presented along with data analysis and conclusions     

Induction Watthour Meter Accuracy with Non-Sinusoidal Currents

This paper is concerned with the accuracy of registration of induction watthour meters when metering non-sinusoidal currents. Expressions are given for the meter registration errors for three cases of nonsinusoidal current wave forms: (1) full wave, phase triggered sinusoid (2) full wave, phase delayed square wave (3) full wave, battery charger wave errots in registration are found to be a function of the harmonic distortion of the impressed current and the ratio of impressed rms current to rated or class current. A generalization of this study is made, relating error to these two variables. It is suggested that a bound on the product PH?k will similarly bound registration error. PH is the per unit harmonic distortion of the current and k is the per unit rms current in the watthour meter.     

Unified phase-coordinate load-flow and fault analysis of polyphase networks

The steady-state load-flow and fault analyses of polyphase power networks using the method of phase coordinates are described. Examples with solutions are given of complex multiple unbalanced load flow and simultaneous fault problems. The paper illustrates the capability of the method to extend the range of power system network analysis beyond the scope of transformation methods, such as the symmetrical component method, without incurring any increase in model complexity.     

Watthour meter accuracy under controlled unbalanced harmonicvoltage and current conditions

This work presents the results of phase I of the project on the accuracy of watthour meters when subjected to closely-duplicated real-world unbalanced harmonic voltage and current conditions. Such real-world conditions involved differences in voltage and current magnitudes as well as differences in the voltage and current total harmonic distortion levels of each phase. Tests were performed on a selected sample of nine three-phase and three single-phase watthour meters. Some results showed that under a particular set of unbalanced waveforms with harmonic conditions of I_THD>80% and V_THD>2%, the percentage errors exhibited by these meters ranged from -10.09% to +0.52%     

电能表现场校验技术研发应用现状及其发展趋势（下）

较全面地梳理了国内外电能表现场校验技术、校验装置的研究和应用现状。注意到接收数字量的数字化电能表的现场校验方法有待深入研究,数字化电能计量量传体系急需建立;电力负载的强非线性、波动性和随机性,对如何准确计量其实际耗用的电能,以及如何校验电能表的计量准确性等均提出了挑战。在此基础上,展望了电能表现场校验技术的进步方向及发展趋势。     

Massively parallel systolic‐array architectures for 2d IIR polyphase space–time plane‐wave beam digital filters

A systolic architecture has recently been proposed for implementing two‐dimensional infinite impulse response (IIR) space–time beam plane‐wave filters at a throughput of one‐frame‐per‐clock–cycle for such applications as real‐time broadband smart antennas. A novel polyphase systolic architecture is proposed here that further increases the throughput of these IIR beam filters, by a factor of M, to M‐frames‐per‐clock‐cycle, where M is the number of polyphases. The proposed method combines the polyphase approach, along with pipelining and look‐ahead optimization methods, to achieve frame sample frequencies that are several times higher than the clock‐cycle limit of the very large‐scale integration (VLSI) technology, thereby potentially allowing multi‐GHz frame sample frequencies using current custom VLSI circuits. The implementation of a field programmable gate array‐based real‐time prototype is described, tested and verified for the two‐phase case (M = 2) at a technology‐limited clock frequency of 50 MHz which corresponds to a throughput of 100 million‐frames‐per‐clock–cycle. Copyright © 2010 John Wiley & Sons, Ltd.     

Fault analysis and component schemes for polyphase power systems

The application of component schemes for the analysis of fault currents in polyphase power systems is discussed. In particular, real transformations to components are derived, which are useful for transient analysis. Several possibilities are considered that are generalizations of the Clarke component scheme used for 3-phase power systems. It is shown that some schemes are valid only for polyphase power systems with complete phase transposition. The application of these real components to several types of shortcircuits is considered. Physical interpretation of the symmetrical and real components is made.     

Dynamic performance prediction of polyphase hysteresis motors

The dynamic performance characteristics of polyphase hysteresis motors are presented. A mathematical model to predict the starting and synchronization process of such motors under various operating conditions is given. The model offers a tool for studying the dynamic stability of the hysteresis motor for small-scale disturbances such as changes in load torque, supply voltage, and frequency. A parametric variation is provided to highlight effects of varying some of the critical quantities like hysteresis lag angle, recoil permeability, and rotor dimensions. Two experimental rotors made of 36% and 17% cobalt-steel alloys were used in this investigation. Simulations of the dynamic behaviors of the two motors are presented. There exists a reasonably close agreement between the simulated and measured results     

Effect of transmission line loading on the performancecharacteristics of polyphase distance relay elements

The performance characteristics of a polyphase element for the detection of phase faults is examined. The results show the effect of transmission line loading and reach setting on the detection characteristics of forward faults. The polyphase element exhibits tendencies to under-reach for far-end as well as close-in faults with zero fault resistance, under some conditions. The results are presented in a manner that facilitates ready assessment of the expected performance of a polyphase element in a particular application     

经电子互感器接入静止式电能表的检定方法

随着小模拟量电压信号电子互感器的推广应用,需要对与其配套的经电子互感器接入的静止式电能表进行检定试验。此类电能表与传统电磁式互感器的电能表在输入信号、检定方式等方面存在不同,检定设备及方法也有变化。由于没有相应的检定设备,需利用传统的三相电能表的标准检定装置,结合标准信号转换装置进行电能表准确度试验,同时检定项目增加小模拟量电压信号的阻抗匹配测试。论文介绍的检定方法,为推广经电子互感器接入的静止式电能表在电子互感器计量系统中的应用,提供了重要的检定方法和依据。     

降低电能计量装置综合误差综述

电能计量的准确性直接关系到供用电双方的经济利益。由于电能表、电流互感器、电压互感器及二次回路中存在的各种问题,直接影响电能计量的准确性,严重时会危及电力系统的稳定运行,文章针对电能计量装置产生误差的各种原因进行了分析,并提出了相应的改进措施。     

Analysis of mismatch impact on image rejection ratio for passive polyphase filters

Passive polyphase filters (PPFs) are useful symmetric RC networks for processing analog quadrature signals. Passive polyphase filters are also used to implement differential‐quadrature or quadrature‐differential converters. The quality of these quadrature signals is essential to achieve good performance in modern communication systems. However, mismatch effects can produce notable degradation in the PPF frequency response, and this results in an important reduction in quadrature signal quality, being amplitude balance and phase offset notably affected. Both these errors could be summarized and evaluated together considering image rejection ratio as a figure of merit. This work deepens in the analysis of mismatch impact on PPF, studying image rejection ratio degradation for 2 PPF types, and a systematic method is proposed to obtain the worst case of mismatch in PPFs with any number of stages. It has been validated in a 65‐nm CMOS technology.     

Sensitivity of Electrical Appliances to Harmonics and Fractional Harmonics of the Power System's Voltage. Part II: Television Sets, Induction Watthour Meters and Universal Machines

The sensitivity of television sets, induction watthour meters and universal motors to harmonics and fractional harmonics, as they occur in home appliances, is derived analytically and experimentally. This study shows that television sets are very sensitive to fractional harmonics. Calculations and measurements performed with single-phase watthour meters show that the harmonic torques within the aluminum disk are always positive and accelerate the disk. Universal machines are not as sensitive to voltage harmonics as compared with induction machines. The work described has been supported by the U.S. Department of Energy.     

Harmonic compensation of induction watthour meter performance

This paper analyzes the variation of the registration error of an induction watthour meter (IWHM) with respect to those parameters concerning the harmonic characteristics of the load and harmonic performance of the IWHM. Based on an analysis of the results of error variation, two types of compensation methods, namely, meter external methods and meter internal methods, are proposed to improve the accuracy of the IWHM when operated in harmonic situations. The meter external methods are related to the harmonic characteristics of the load, while the meter internal methods are associated with the harmonic performance of the IWHM. Each compensation method is comprised of several measures. This paper presents these measures for each compensation method, and gives detailed illustrations of the practical aspects for each measure. The feasibility of each compensation method is assessed, and some useful suggestions for utilities, users and manufacturers of IWHMs are offered. The study results show that the registration error due to constant single power harmonic interference can be fully compensated. When multiple power harmonics exist, however, the compensation, in general, can only focus on the main harmonic component to reduce the registration error to as low as possible. The effectiveness of those compensation methods which are feasible has been confirmed by the experimental results.     

一种用于大型风电机组叶片自重载荷标定的弯矩解析方法研究

在大型风电机组的机械载荷测试中,叶片自重引起的摆振弯矩和挥舞弯矩的载荷标定精确度直接影响叶片和风轮的载荷测试效果。因此分析叶片自重在应变片测量位置的弯矩解析结果是叶片载荷标定的关键。首先,运用解析几何原理,提出了一种基于优选的三维坐标系和坐标变换的叶片自重弯矩解析方法。其次,为了消除主轴倾角对优选的三维坐标系的影响,提出了一种在优选的三维坐标系中调整叶片重力矢量方向的方法,并推导出了考虑各种影响因素下的弦摆振弯矩、弦挥舞弯矩的解析表达式。最后,在实际的叶片载荷测试项目中,应用两种标定分析方法进行对比,两种方法得到的叶片载荷测试结果具有很好的一致性和代表性。理论分析和试验结果验证了本文所提的叶片自重弯矩解析方法对叶片载荷标定的有效性和可行性。     

高压电能计量装置特殊接线及其分析

通过对一用户的35kV高压计量装置的特殊接线进行深入分析,介绍论了三相电能表在一般情况下可以正确计量的三种接线方式,对两种不常用的接线方式在特殊条件下能否计量进行了讨论,并得出了结论。     

失压后多功能电表差错电量的计算

电力企业在处理计量故障时,原有计算更正系数及追补电量方法的应用对象主要是机械式感应电能表,随着多功能电子式电能表技术的大面积运用,由于电能表电压回路内部结构原理的不同,在失压时对计量的影响与感应式电能表有很大区别。通过多年工作经验总结出了三相三线多功能电子式电能表在各种失压状态下的运行情况及如何正确进行有功、无功退补电量的K值计算方法。