Static Meters Research Articles

Active Energy Meters Tested in Realistic Non-Sinusoidal Conditions Recorded on the Field and Reproduced in Laboratory

Metrological characterisation of static energy meters under realistic low power quality conditions is a basic requirement for proper grid control and fair energy billing. The paper reports about a new proposed methodology, where the meters are tested under conditions directly recorded at installation sites. The waveforms of voltages and currents are sampled using a portable instrument; they are reproduced in laboratory conditions with a phantom power generator, with a bandwidth covering up to the 40th harmonic. The recording site is a photovoltaic energy production facility, having a a nominal power of 50 kW, at the coupling section to the grid. These waveforms were then reproduced in the laboratory, and tested on different models of single- and three-phase commercial static energy meters; the models chosen represent both energy meters used by energy providers at the point of common-coupling, and also meters typically used for in-line monitoring by end users. The quantity of interest is the reading error of the measured energy, when tested with the conditions reproduced from the on-field measurements, in comparison with a reference meter. All tested energy meter models comply with the present international documentary standards, which require tests under low power quality conditions; nevertheless, there are models that show unacceptable errors (up to 25%) in the measurement of active energy when tested with the on-field recorded waveforms. This suggests that the standardised testing waveforms might, in some cases, be not fully representative of the actual conditions encountered in the field.

Reliability of Domestic Gas Flow Sensors with Hydrogen Admixtures.

Static flow sensors (e.g., thermal gas micro electro-mechanical sensors-MEMS-and ultrasonic time of flight) are becoming the prevailing technology for domestic gas metering and billing since they show advantages in respect to the traditional volumetric ones. However, they are expected to be influenced in-service by changes in gas composition, which in the future could be more frequent due to the spread of hydrogen admixtures in gas networks. In this paper, the authors present the results of an experimental campaign aimed at analyzing the in-service reliability of both static and volumetric gas meters with different hydrogen admixtures. The results show that the accuracy of volumetric and ultrasonic meters is always within the admitted limits for subsequent verification and even within those narrower of the initial verification. On the other hand, the accuracy of the first generation of thermal mass gas flow sensors is within the limits of the verification only when the hydrogen admixture is below 2%vol. At higher hydrogen content, in fact, the absolute weighted mean error ranges between 3.5% (with 5%vol of hydrogen) and 15.8% (with 10%vol of hydrogen).

Uncertainty in discrete-time integration — The case of static gas meters

We consider the evaluation of uncertainty in a particular case of discrete-time integration, i.e., that of static gas meters. We show that the current approach, which does not take correlations into account, can lead to underrating of the uncertainty associated with the estimate of the delivered volume. Now, a correct evaluation of uncertainty in the case e.g. of online measurements along large offshore pipelines is important in order to remove technical barriers to international trade.We focus our discussion on the practical example of gas meters, but the framework of uncertainty evaluation we provide is valid in general for all those measurements involving discrete-time integration, and has therefore a wide applicability.

Interference on Static Energy Meters Resulting From Droop of the Current Transformer

Interference on Static Energy Meters Resulting From Droop of the Current Transformer

Preparation and characterization of modified activated carbon-based shape stabilized eutectic phase change materials for gypsum composites application

Modified SAT-urea eutectic salts (EPCM) as the phase-change materials were prepared using modifiers such as disodium hydrogen phosphate dodecahydrate (DHPD) and carboxymethyl cellulose (CMC). The support material, hydrophilic modified activated carbon (MAC), was prepared using OP-10 as a hydrophilic modifier. The vacuum impregnation method was used to fabricate the MAC-based shape-stabilized eutectic phase-change materials (SSEPCM). The gypsum-based building materials with thermal storage capacity were obtained by compositing surface-treated SSEPCM and gypsum. The surface contact angle, surface functional group, phase transition temperature, latent heat, phase composition, and microstructure of the SSEPCM were examined using the static contact angle meter, Fourier infrared spectrometer, in-situ infrared spectrometer, differential scanning calorimeter, X-ray diffractometer, and scanning electron microscope. The adsorption capacity of MAC increased first and then decreased with the increase of OP-10 content in the modified solution. When the OP-10 content was 0.3 wt%, the contact angle between the surface of MAC and water reduced to 0°, and the mass fraction of EPCM relative to MAC was 93.1 wt%. The results showed that the OP-10 had a good hydrophilic modification effect on the granular activated carbon. The X-ray diffractometer and differential scanning calorimeter results of SSEPCM indicated that there was no chemical reaction between EPCM and MAC, the phase transition temperature was 32.11 °C, and the latent heat was 103 J/g. The latent heat loss rate of SSEPCM was 5.8 % after 100 thermal cycles, and the number of –OH did not decrease during the heating process of SSEPCM, which showed that SSEPCM had good thermal stability. The flexural and compressive strength values of the SSEPCM/gypsum composites were 2.50 MPa and 7.36 MPa, respectively, when 45 wt% SSEPCM was incorporated into the gypsum matrix, which was sufficient for practical applications. The introduction of SSEPCM could slowly reduce the thermal conductivity and significantly improved the thermal inertia of the composites.

Static Energy Meters and the Electrical Environment Comply to the Standards But are Not Compatible

The energy transition contributes to a more sustainable use of electricity. Consequently, the loads that are connected in the electricity grid change from conventional linear loads towards non-linear time-variant loads, which are usually more energy efficient. This has resulted in many conducted electromagnetic interference problems, of which the interference on static energy meters is an impactful case as it can result in higher energy bills for consumers. This issue occurs when highly pulsed loads are connected to the static energy meter. For example, coming from a commercial off-the-shelf water pump, where errors up to 2675% are found, or from switching multimedia equipment resulting in a power generation of more than 600 W without any power generating equipment connected. Therefore, this article compares the interference waveforms with the waveforms as included in the relevant directives and standards. It is found that the test standards only cover frequency domain test methods, while the interference waveforms are more wide-band. Furthermore, those test methods do not cover the wide variety of waveforms that occur in the residential environment were the static energy meter is placed in.

Susceptibility of Static Energy Meters due to Amplifier Clipping Caused by a Rogowski Coil

Static energy meters installed in households, used for billing purposes of the energy consumption, have shown errors due to conducted electromagnetic interference coming from appliances in household situations. This resulted in over- and underestimations of the energy bill, and even in a perceived energy generation. The currents causing interference are known to be nonlinear pulsed currents with fast slopes. This article shows that clipping of the amplifier, following the Rogowski coil, which is used as the current sensing element, results in distorted energy measurements. Due to the pulsed nature of the current, the output of the Rogowski coil exceeds the maximum input voltage of the amplifier, resulting in clipping at the output of the amplifier. This clipped signal is then integrated in the digital chain, resulting in an offset in the perceived current. Hence, causing a higher or lower energy calculation, depending on the phase firing angle and the fastest edge of the pulse. It is found that parameters, such as the slew rate, rise and fall times, and firing angle, are correlated to the interference on static energy meters.

Study on Silica Aerogel Modified by Trimethylchlorosilane

The mechanical properties of SiO2 aerogel prepared under atmospheric pressure are poor, so it is difficult to prepare large pieces of materials for practical engineering. In this paper, trimethylchlorosilane (TMCS) was used as a surface modifier to transform hydrophilic substances with higher surface activity into hydrophobic groups, to improve the network strength of SiO2 aerogel. Super-hydrophobic SiO2 aerogel was prepared by the sol-gel method under atmospheric pressure. The effects of trimethylchlorosilane on the structure and properties of SiO2 aerogel were characterized by a specific surface area analyzer, Fourier transform infrared spectrometer, thermal conductivity meter, static contact angle meter, and scanning electron microscope. The results show that the SiO2 aerogel prepared when n (Si):n (TMCS) is 1 has the best performance. Its density is as low as 0.0759 g/cm3, the porosity is as high as 96.5%, the specific surface area is as high as 723.08 m2/g, and the contact angle is 163.8°. It has good hydrophobic properties.

Environmental sustainability and life cycle cost analysis of smart versus conventional energy meters in developing countries

The sustainability of smart energy meters (SM) in comparison to conventional static energy meters (CM) in developing regions of the world is an area of rising interest and research. The study aims at the characterization of the environmental and economic sustainability of SMs in context to developing low-middle income countries like Pakistan. Life cycle assessment (LCA) and life cycle costing (LCC) methods have been used for the requisite analysis. While 6 midpoint categories; climate change potential (CCP), ozone depletion potential (ODP), terrestrial ecotoxicity potential (TETP), fossil resource scarcity potential (FFP), water consumption potential (WCP) and 1 endpoint category; damage to human health have been selected. Highest impact scores have been determined in CCP, FFP, WCP i.e., 9.61E+00 and 7.60E+00 kg CO2 eq., 9.59E+00 and 7.77E+00 kg oil eq., 6.98E+00 and 6.69E+00 m3 water for CM and SM respectively. The overall highest impact is contributed by the production phase for both type of energy meters. In LCC analysis the initial cost of SM and CM has been calculated as 52.76 USD and 47.52 USD respectively, while the overall life cycle cost of SM is 61% less than that of CM. As such there are significant environmental and economic benefits of the deployment of SM as determined under the complete life cycle perspective. There is still a long lag to be covered by developing countries for the deployment of such smart-sustainable technologies. Policy interventions and roll-out programs can establish that SM not just an electricity metering system, rather is a comprehensive communication portal for buyers and sellers.

Estimation of Static Energy Meter Interference in Waveforms Obtained in On-Site Scenarios

Static energy meters have shown errors beyond the standards due to conducted electromagnetic interference of pulsed currents. This was observed in several case studies and confirmed by laboratory experiments, which showed errors up to 2675%. The extent of this interference case is unknown, because there is limited information about the waveforms occurring in the real on-site scenarios. This article aims to detect critical waveforms in on-site surveyed data that have similar characteristics as the pulses that resulted in metering errors. The time-domain parameters of the laboratory experiments that show static energy meter interference are compared to the on-site waveform data using an interpolation based on an inverse weighting distance function. Using this approach, the waveform characteristics are compared, and an error is estimated. This approach was satisfactorily validated using data from validation experiments that shows a correct estimation of the actual error according to the permissible limits for energy metering for all validation indices. The performed on-site surveys show the existence of nonlinear waveforms. During the survey of three sites for ten days, 19 531 waveforms were captured, of which 14 487 indicate large nonlinearities and 379 are estimated to produce metering errors up to 925%.

Statistical Time-Domain Analysis of Equipment in Low-Voltage Networks

The increased use of non-linear equipment results in conducted electromagnetic interference problems. As an example, static energy meters, used to measure the energy consumption in households, show misreadings due to pulsed currents from a speed controlled water pump or dimmed lighting equipment. To determine the existence of similar equipment in low-voltage networks, this letter surveys current waveforms drawn by equipment in the low-voltage network. These waveforms are analyzed and compared to critical waveforms from previous research that caused static energy meter interference. In this way the extent of critical situations in a real-world environment is determined. The equipment survey is performed using a multi-channel timedomain measuring method able to capture the voltage and currents synchronously. Then using a time-domain parametric model a statistical overview of parameters such as the charge, crest factor, peak value, pulse duration, and rising slope is given. The survey shows the existence of a large variety of non-linear signals, and 43% contained critical parameters related to static energy meter interference.

EMC Testing of Electricity Meters Using Real-World and Artificial Current Waveforms

In 2015, the energy measurement of some static electricity meters was found to be sensitive to specific conducted electromagnetic disturbances with very fast current changes caused by highly nonlinear loads, leading to meter errors up to several hundred percent. This article describes new results on the electromagnetic compatibility (EMC) of 16 different meters from all over Europe when exposed to real-world disturbance signals. Those test signals were obtained from household appliances and onsite measurements at metered supply points all over Europe. The results show that also the interference signals recorded onsite can cause measurement errors as large as several hundred percent, even for meters that pass the present EMC standards. This unambiguously demonstrates that the present immunity testing standards do not cover the most disturbing conducted interference occurring in present daily-life situations due to the increased use of nonlinear electronics. Furthermore, to enable the adoption of potential new test waveforms in future standards for electricity meter testing, artificial test waveforms were constructed based on real-world waveforms using a piece-wise linear model. These artificial test waveforms were demonstrated to cause meter errors similar to those caused by the original real-life waveforms they are representing, showing that they are suitable candidates for use in improved standardization of electricity meter testing.

IMPROVEMENT OF THE OPERATION PROCESS OF WATERED DEEP OIL PUMP WELLS BY APPLICATION OF POLYFUNCTIONAL MEASURES

The article shows the types of complications that occur mainly in the fields of the Absheron archipelago in Azerbaijan and in the oil fields of the Azerbaijani sector of the Caspian Sea; the most common and frequent of them are the watering of the production of sucker rod pumping wells and the intensity of sand manifestations. It is noted that methods that prevent complications or reduce their negative impact are more appropriate than methods for their elimination. It is proposed to isolate formation water in flooded sucker-rod pumping oil wells using a universal hydrodynamic method; In this method, a liquid barrier should be created in front of the water in the formation, and not a solid barrier, and high-viscosity dead (non-gaseous) oil should be taken as a separating fluid, the specific gravity of which should be equal to the specific gravity of the formation water. The article uses the following five functions of multifunctional measures when carrying out various well survey methods: I. Pouring clean fluid into the annulus to increase the amount of fluid in the wellbore and reduce the concentration of sand particles in it. II. Without stopping the operation of the pumping unit, adding clean oil to the annulus with the help of a unit, raise its static level several meters higher. III. Determination of values of Pk, Po and G in rod deep well pumping wells producing viscous-plastic oil without stopping the operation of the pumping unit. IV. To determine the reservoir pressure in the simplest way, all well production is drained with a hose into the annulus. V. When removing the first lower curve by the method of two-sided restoration of curves without stopping the operation of the pumping unit VI. When applying the extraction method without changing the indicator diagrams S and n of water-cut oil wells. Thus, the use of multifunctional measures improves the performance of the considered wells and provides great economic benefits. Keywords: polyfunctional measure, irrigated well, sand manifestation, corrosion, erosion, wear, complication, pipe space, sand concentration in liquid, recovery curve.

Waveform Model to Characterize Time-Domain Pulses Resulting in EMI on Static Energy Meters

This article presents a time-domain waveform model developed to characterize pulsed, nonlinear, current waveforms resulting in electromagnetic interference on static energy meters. The waveform model is calculated by fitting the sampled waveform data into a linear piece-wise function through a process that involves applying algorithms of pulse extraction, change-point detection, and redundancy elimination. The model is applied to data from laboratory experiments that have indicated critical current waveforms resulting in electromagnetic interference problems with static meters. Afterwards, the parameters of the modeled waveforms are calculated in order to correlate them to metering errors. The most relevant parameters that are correlated to significant errors are the maximum slope, crest factor, pulse duration, and charge. The waveform model provides an accurate description of the complex nonlinear waveforms through simplified analytical expressions that reproduce the significant features of the interfering waveforms. This waveform modeling approach could be used to standardize the artificial test signals that are representative of realistic devices and scenarios.

Experimental Assessment of Gas Static Meters Under Different Operating Conditions

This paper compares the metrological performance of a sample of commercial domestic/residential smart meters for natural gas (G4). In particular, the performance degradation of electronic static and dynamic gas meters has been evaluated. The sample was composed by ultrasonic gas meters, thermal mass meters and diaphragm gas meters. The tests, performed on the gas meters, reproduce the most severe operating conditions (i.e. filed test) such as the influence of the gas composition, the temperature difference between gas and meter, the gas humidity and the presence of dust in the gas. Furthermore, the meters have been undergo to some endurance tests such as start and stop and to the high flowrate runs.

Energy Metering Integrated Circuit Behavior beyond Standards Requirements

During the last few years, the accuracy of static electricity meters (SEM) has been questioned. Significant metering deviations with respect to a reference meter have been observed at customer premises, and laboratory experimental tests results support such findings. The root cause of such errors remains unknown, as there are multiple elements that could affect the accuracy of electricity meters. Furthermore, standard compliant meters exposed to distorted signals may produce negligible, positive or negative relative error depending on the instrument design. Distorted current signals with fast amplitude transitions have produced the highest error in SEMs reported in the literature. In this paper, the accuracy of an energy metering Integrated Circuit (IC) is evaluated beyond the limits of the standards requirements employing a selection of distorted signals from the standards, real-world captured signals and a set of waveforms designed to test the IC under fast changing currents conditions, which are representative of the waveforms resulting from power electronic devices. The experimental results reveal an accuracy boundary imposed by Gibb’s phenomenon for fast changing current signals and a strong relationship between the IC’s measurement error and two key parameters of the measured waveform: signal slope and phase angle. This paper therefore provides a methodology for the comprehensive analysis of SEMs in future power systems which are dominated with power electronic-controlled electrical demand and contributes to the search for the root cause of error in SEMs exposed to distorted waveforms.

Reduction of Static Electricity Meter Errors by Broadband Compensation of Voltage and Current Channel Differences

To compensate for the different transfer functions of the current and voltage input stages of static electricity meters, usually, a time correction is applied, which is suitable for sinusoidal signals. However, for highly distorted signals, in which the high-frequency content is significant, this method is insufficient and reading errors will not be fully compensated. For such waveforms, this article describes two alternative methods to deal with the different input stages. The methods are implemented on a home-built waveform recorder, modified as static electricity meter, and validated using their influence on energy-reading errors for various waveforms and input stages (impedance and coupling). Apart from highly distorted current signals, also the effect of finite source impedance is considered by modifying the voltage waveform accordingly, which potentially influences the observed meter errors as well. The inverse-filtering method is the most powerful method but is computationally intensive and, therefore, more suitable for high-accuracy power meters than for inexpensive electricity meters. The less computationally intensive equivalent-filtering method shows very good results as well and is a better candidate to be implemented in electricity meters. The latter is especially relevant because of recent results, showing that some electricity meters are sensitive to specific disturbances beyond the present standard test waveforms.

Experimental Study of Harmonic Influence on Electrical Energy Metering

The paper considers the influence of harmonics on the operating of electrical energy meters in a network with nonlinear loads. It is shown that electronic static meters of active energy are tested in the presence of distortions, and electronic static meters of reactive energy accuracy requirements do not take into account the possible presence of harmonics. It is revealed that the maximum influence on the error in active energy metering is exerted by the number of harmonics taken into account and their amplitude, and the error in reactive energy metering is additionally influenced by the phase angle at the fundamental and harmonic frequencies, which has been confirmed in laboratory conditions. Additionally, experimental studies of the capacitor bank’s influence on reactive energy metering has been carried out in the presence of nonlinear electrical loads. It is shown that when capacitor banks are connected, the error in reactive energy measurement and variation range of the phase shift angle of harmonics significantly increases. The assessment of the computational error of reactive power metering according to various equations were carried out based on the field measurements. If the voltage and current distortion values do not exceed the permissible values, the error can be estimated at, at most, 5–7%.

Electromagnetic Compatible Energy Measurements Using the Orthogonality of Nonfundamental Power Components

Measurement bandwidth of energy measurements are increasing to incorporate all the harmonics created by nonlinear loads and distributed generators making the measurement electronics complex and sensitive to electromagnetic interference. This article proposes to change the accuracy paradigm by focusing on fundamental active power and lower harmonics for energy metering, simplifying the electronics and making them robust against electromagnetic interference. Using the orthogonality of power flow via Parseval's theorem, a theoretical analysis, simulations, and measurements on power calculations using the fundamental active power are presented. It is shown that a perfect power measurement is achieved with a pure 50 Hz supply voltage, regardless of the nonlinear current. Even with the highest allowed harmonic distortion of the voltage and the current as listed in the international standards EN 50160 and IEC 61000-3-2, more than 97.5% of the active power is contained in the fundamental active power. Negligible active power is contained in the higher frequency components. This error margin falls within limits for electricity meters. Filtering the current with a basic low-pass filter can prevent the erroneous measurements that have appeared with static energy meters. In other words, it has been proven that negligible energy flows in the higher frequency components.

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.