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Erratum
This erratum corrects an error in the article, “Comparing Low‐Flow Accuracy of Mechanical and Electronic Meters,” by McKenna L. Sumrak, Michael C. Johnson, and Steven L. Barfuss, in the June 2016 issue of Journal AWWA (Vol. 108 No. 6, p. E327). The error was found in Table 3 for the value for the nutating disc meter type in the 1–8 column. 3 Comparative performance of new 5/8‐in. ¾‐in. meters Flow Ratea gpm Meter Type 1/16 1/8 ¼ 1 2 15 EMb 1 (0.52) 1 (0.84) 1 (0.55) 1 (0.81) 1 (0.45) 3 (0.55) ND 3 (32.22) 5 (22.5) 5 (5.10) 2 (1.15) 3 (0.52) 2 (0.46) OP 4 (52.27) 3 (11.72) 4 (2.43) 3 (1.51) 5 (1.29) 1 (0.27) MJ 5 (86.64) 4 (21.98) 3 (1.23) 4 (1.98) 4 (1.21) 4 (0.90) SJ 2 (7.41) 2 (2.30) 2 (0.93) 5 (3.32) 2 (0.47) 5 (1.67) Source: Utah Water Research Laboratory EM—electronic meter, MJ—multi‐jet, ND—nutating disc, OP—oscillating piston, SJ—single jet aNumbers indicate meter ranking from 1 to 5 (1 being the most accurate and 5 being the least accurate) with average difference of flow registered from 100% (in parentheses). Ranking is based on difference in percentage. See Figure 1 for sample data calculation. bUltrasonic and electromagnetic meters are combined and referred to as EM.
Journal Article
Accuracy of Solid-State Residential Water Meters under Intermittent Flow Conditions
Accurate water consumption measurement of customers is a crucial component of water utility sustainability. During the last decade, sophisticated measuring technologies without moving components, known as solid-state water meters or static meters, have emerged. Solid-state water meters promise an improved accuracy with more processing and transmission capabilities in comparison with traditional mechanical meters. A compromise needs to be reached between energy consumption and battery life as all these new features are extremely demanding on electric energy. The usual approach adopted by the manufacturer is to reduce the frequency with which static meters take measurements of the circulating flow. This reduction in signal sampling frequency can have a significant effect on the accuracy of the instruments when measuring water consumption events of 30 s or less, these events being common in residential customers. The research presented analyses of the metrological performance of 28 commercially available solid-state water meters from six different manufacturers in the presence of intermittent flows of various durations. The results show that the magnitude and dispersion of the error under intermittent flows is significantly larger in comparison to steady state flow conditions. The ultrasonic meters examined were more influenced by the intermittency than the electromagnetic meters.
Journal Article
Review of results on smart‐meter privacy by data manipulation, demand shaping, and load scheduling
Simple analysis of energy consumption patterns recorded by smart meters can be used to deduce household occupancy. With access to higher‐resolution smart‐meter readings, we can infer more detailed information about the household including the use of individual electric appliances through non‐intrusive load monitoring techniques. The extent of privacy concerns caused by smart meters has proved to an obstacle in the roll‐out of smart meters in some countries. This highlights the need for investigating smart‐meter privacy. Mechanisms for ensuring smart‐meter privacy fall in broad categories of data manipulation, demand shaping, and load scheduling. In smart‐meter data manipulation, the smart meter collects real, potentially high‐resolution data about the energy consumption within the house. This data is then manipulated before communication with to utility providers and retailers. The manipulation could be non‐stochastic, such as aggregation, binning, and down‐sampling, or stochastic, such as additive noise. In demand shaping and load scheduling, smart‐meter readings are communicated without any interference but the consumption is manipulated by renewable energy sources, batteries, or shifting loads to render non‐intrusive load monitoring ineffective. In this study, the author reviews these approaches and presents several methods relying on homomorphic encryption, differential privacy, information theory, and statistics for ensuring privacy.
Journal Article
Analog and Digital Meters
The indication of electrical parameters such as AC voltage, DC voltage, AC current, DC current and frequency is an important task of electronic measurements. There are two modes of indication; (1) analog and (2) digital. Analog meters are used for analog indication and digital meters are used for digital indication. An analog meter is a device that features a printed display to indicate any electrical parameter. An example could be the energy consumed by a typical business, or electrical device. Also called an electromechanical meter, it offers an easy-to-read display. Digital meters are the product of the latest developments in electronic technology, so it is to be expected that they will incorporate many features that are not available in typical moving-coil meters. As well as a wide selection of voltage, current and resistance ranges (including accurate low-resistance range) many of these meters also provide for measurements of capacitance and frequency. This book describes both analog and digital meters.
eBook
Economy Value of High Precision Ultrasound Flowmeter
In order to improve the measurement accuracy of intelligent water meter, a high precision ultrasonic flowmeter is designed. The device integrates the functions of CPU, DSP and FPGA on one chip to complete the timing function, which effectively improves the integration and stability of the system. The system uses time difference method to measure liquid velocity, and uses DSP Slices of Xilinx Corporation to complete smoothing filter function. The measurement accuracy is high and has a good application prospect.
Journal Article
An empirical analysis of residential meter degradation in Gauteng Province, South Africa
Understanding the degradation rates of water meters assists utilities in making informed management decisions regarding meter replacement programmes and meter technology selection. This research evaluated the performance of 200 residential meters of two diferent technologies commonly used in Gauteng, South Africa, namely velocity meters and volumetric meters. This was done by conducting empirical meter testing in a verification laboratory and evaluating the degradation accuracy of each meter technology based on age and volume. Results indicate that velocity meters experience an accuracy degradation rate of approximately −1.13% per 1 000 kL of volume passed through the meter and an inferred initial error of −10.80%. Meter accuracy was not strongly related to age of the velocity meters tested. Volumetric meters did not exhibit a strong link with either age or accumulated volume, indicated by a loose grouping of results. These results indicate that accumulated volume of a velocity meter is a more reliable predictor of accuracy than age, and should be used when planning replacement strategies for velocity meters. Additionally, the lack of predictable degradation rates related to either age or accumulated volume for volumetric meters indicates that the accuracy of volumetric meters is primarily afected by other external factors, such as particulates or entrained air in the water network. These findings will assist utility managers in predicting the accuracy of their meter fleet and in making informed decisions regarding meter replacement.
Journal Article
Highly-Linearized Heterodyne Self-Mixing Vibrometer
Vibration meters based on self-mixing interferometry are generally made in baseband, without modulations, because it is very difficult to obtain a linear modulation of the wavelength by controlling the supply current. In this paper, it is shown a multi-frequency modulation strategy for a heterodyne self-mixing vibrometer, which allows us to overcome the limits of frequency estimation algorithms and can work on a diffusing target up to a few meters away.
Journal Article
Study of the Effects of Changes in Gas Composition as Well as Ambient and Gas Temperature on Errors of Indications of Thermal Gas Meters
Thermal gas meters represent a promising technology for billing customers for gaseous fuels, however, it is essential to ensure that measurement accuracy is maintained in the long term and in a broad range of operating conditions. The effect of hydrogen addition to natural gas will change the physicochemical properties of the mixture of natural gas and hydrogen. Such a mixture will be supplied through the gas system, to consumers, including households, where the amounts of received gas will be metered. The physicochemical properties of hydrogen, including the specific density or viscosity, differ significantly from those of the natural gas components, such as methane, ethane, propane, nitrogen, etc. Therefore, it is of utmost importance to establish the impact of the changes in the gas composition caused by the addition of hydrogen to natural gas on the metrological properties of household gas meters, including thermal gas meters. Furthermore, since household gas meters can be installed outdoors and, taking into account the fact that household gas meters are good heat exchangers, the influence of ambient and gas temperature on the metrological properties of those meters should be investigated. This article reviews a test bench and a testing method concerning errors of thermal gas meter indicators using air and natural gas, including the type containing hydrogen. The indication errors for thermal gas meters using air, natural gas and natural gas with an addition of 2%, 4%, 5%, 10% and 15% hydrogen were determined and then subjected to metrological analysis. Moreover, the test method and test bench are discussed and the results of tests on the impact of ambient and gas temperatures (‒25 °C and 55 °C, respectively) on the errors of indications of thermal gas meters are presented. Conclusions for distribution system operators in terms of gas meter selection were drawn based on the test results.
Journal Article
Distributed meter data aggregation framework based on Blockchain and homomorphic encryption
A significant progress in modern power grids is witnessed by the tendency of becoming complex cyber‐physical systems. As a fundamental physical infrastructure, smart meter in the demand side provides real‐time energy consumption information to the utility. However, ensuring information security and privacy in the meter data aggregation process is a non‐trivial task. This study proposes a distributed, privacy‐preserving, and secure meter data aggregation framework, backed up by Blockchain and homomorphic encryption (HE) technologies. Meter data are aggregated and verified by a hierarchical Blockchain system, in which the consensus mechanism is supported by the practical Byzantine fault tolerance algorithm. On the top of the Blockchain system, HE technology is used to protect the privacy of individual meter data items during the aggregation process. Performance analysis is conducted to validate the proposed method.
Journal Article