Active Power Measurement Research Articles

Active Power Measurement Accuracy Increasing by Additional Measurement of Shunt Voltage

The broadband transfer power wattmeter with the correction of the own consumption error for measuring the active power against the background of large reactive components in the radio frequency range is considered in article. The objects of research are electromagnetic elements (chokes / transfor­mers), operating at high frequencies and have strongly distorted forms of signals.
 When measuring at high frequencies, the channels of the wattmeter become very sensitive to phase errors. It is necessary to minimize links that cause phase shifts. In this connection, it is important to correctly construct the input units of the wattmeter and to make such a transformation, which will provide operations with signal rms valueswithout links phase shifts. The proposed scheme allows this to be achieved, and required gain is carried out without taking into account the phase shift of the signals.
 In the basic scheme of the wattmeter(fig. 1), the input device is executed from the main shunt and parallel to the auxiliary distributed shunt connected to it, which is connected to the main resistance of the voltage divider, in which the value of all resistances of the input device is determined by conditions of invariance to the squares of the voltage and load current , and the partially distributed auxiliary shunt is calculated with additional weighting factors to provide the conditions for invariance of the squared of voltage and current and eliminate the error from its own revives.
 Features of the construction of the input link of the wattmeter of transfer power with additional measurement of shunt voltage are given in the article(fig.2). Active power with taking into account the influence of the shunt reactive component calculation formulas (7)-(14)is presented.
 The basic error of the wattmeter is the error of the low-ohm shunt. It is expedient to use coaxial or triaxial shunts to extend the frequency range. Transfer power wattmeter input link, which contains additional measurement of shunt voltage simulations was performed in the article(fig.3and table 1).
 The advantages of such wattmeter are:
 
 possibility to expand the frequency range by taking into account shunt resistance reactive component influence on the measurement final result , which can be achieved not only by hardware (shunt inductance reduction), but also the introduction of the calculated correction after measuring the values of the shunt active and reactive component;
 the values of the input device elements can be optimized by the criterion of maximum broadband, since the error from own consumption is taken into account;
 in the scheme one low-level shunt is used, which reduces the cost of the wattmeter;
 additive errors of the voltage conversion channel are minimized.

Specificity of energetic functioning of economic activity objects

Ecology is strongly related to the quality of energy management and to limiting the negative impact of the technosphere on the environment. This work refers to the analysis of energy quality and power balances in different, due to the specificity of functioning (used electrical equipment), business facilities. The research was carried out for supply networks: in the bank building, in the IT laboratory and in the office and warehouse facility. The measurements of currents, voltages, active, reactive and apparent power in individual phases of power supply system as well as distortions (higher harmonics) of currents and voltages were carried out. The research was carried out to identify irregularities in the networks and to indicate ways to limit the effects of electromagnetic disturbances (mainly higher harmonics) as well as achieve improvements in energy efficiency and ecology in the operation of these facilities.

Active power measurement based on digital processing of voltage and current signals

Active power measurement based on digital processing of voltage and current signals

ACTIVE POWER MEASUREMENT ACCURACY INCREASING WITH SIGNIFICANT REACTIVE COMPONENT

The broadband wattmeter of transient power with its own consumption error correction for measuring the active power against the background of large reactive components in the frequency range up to units MHz is described in the article. This instrument can measure the power loss (active power) in a variety of reactive elements, for example, the inductances used in pulsed energy converters. Such wattmeter can be used to optimize the development of wireless power transmission systems based on open resonance circuits. The structure of such systems, as was found during the study, has a spherical directional pattern and does not depend on the emitter and receiver location, described in the article. The article specifies the features of active power measurements at searching for the most efficient design of wireless power transmission systems on the basis of open resonant circuits, where the measurement is complicated by the fact that relatively small active power needs to be measured against the background of large reactive components, when the operating frequencies are shifted from the resonance, and phase shift between current and voltage accrue.At high frequencies measuring, the channels of the wattmeter become very sensitive to phase errors. It is necessary to minimize links that cause phase shifts. In this connection, it is important to construct correctly the wattmeter input units and to make such a transformation, which will provide operations with signal modules. The proposed scheme allows this to be achieved, and required gain is carried out without taking into account the signals phase shift.In the basic scheme of the wattmeter, the input device is executed from the main shunt and parallel to the auxiliary distributed shunt connected to it, which is connected to the main resistance of the voltage divider, in which the value of all resistances of the input device is determined by conditions of invariance to the squares of the voltage and load current, and the partially distributed auxiliary shunt is calculated with additional weighting factors to provide the conditions for invariance of the square of voltage and current and eliminate the error from its own revives.The value of the calculated power measurement error on the model for this wattmeter is 0,1%. The basic error of the wattmeter is the error of the low-ohm shunt. It is expedient to use coaxial or triaxial shunts to extend the frequency range. The designs of such shunts and examples of shunts with the best technical characteristics for today are given in the article.The advantages of such wattmeter are:- gives the exact value of the measured power on the load, regardless of the actual consumption of the input device;- the values of the input device elements can be optimized by the criterion of maximum broadband, since the error from its own consumption is taken into account;- one low-level shunt, which reduces the cost of the wattmeter; is used in the scheme- additive errors of the voltage conversion channel are minimized.

Low cost system to measure active power in electrosurgical units

Abstract Introduction: The real-time measurement of active power delivered to patients during the electrosurgical act is still an engineering challenge. Besides, there is no electrosurgical unit on the market capable of doing it according to the normative requirement. Methods This work presents the design of an electronic structure capable to probe the electrosurgical equipment output electrical signals, using low-costs very common resistors, and High Frequency distortions compensation circuits, and process them to provide an analogue signal proportional to the active power, allowing the knowledge and control of the energy delivered to the biological tissue. The reading circuits and the active power calculation method are presented. The power calculation is performed in two stages. The first one consists of a multiplier circuit that uses the readings voltage and current quantities to determine the instantaneous output power, and the second stage is formed by an integrating circuit which determines the average power value, resulting in a rippled continuous voltage, proportional to the active power delivered to the patient or biological tissue. Results Practical tests of the compensation technical are statistically evaluated by means of linear regressions. Results of 23 tests are summarized in a way to demonstrate de effectiveness of the proposed system. Conclusion Analysis of the results demonstrate the efficiency of the proposed system, whose average error is lower than 5%, and correlating them with the standard IEC 60601-2-2, that regulates the operation of electrosurgery units.

Simplified Approach to Evaluate the Combined Uncertainty in Measurement Instruments for Power Systems

This paper presents the study of the propagation of the effects of uncertainties in a typical measurement system for modern power networks. Nowadays there is a strong demand from the electricity industry of simple and ready-to-use solutions for calculating uncertainty in such “new” measurement systems. To this purpose a simplified approach is presented whose results are shown to be in good agreement with those provided by conventional but more complex methods. Two applications, rather simple but very common, are considered in this paper. In the first one, the measurement of a voltage phasor is considered and the measurement chain is made by an low power instrument transformer (LPIT) and a converter used for adapting the level of signals from the LPIT to the inputs of intelligent electronic device. The second application deals with the measurement of active power of a system made by a low power voltage transformer (LPVT), a low power current transformer and a powermeter.

Non-intrusive load monitoring under residential solar power influx

This paper proposes a novel Non-Intrusive Load Monitoring (NILM) method for a consumer premises with a residentially installed solar plant. This method simultaneously identifies the amount of solar power influx as well as the turned ON appliances, their operating modes, and power consumption levels. Further, it works effectively with a single active power measurement taken at the total power entry point with a sampling rate of 1Hz. First, a unique set of appliance and solar signatures were constructed using a high-resolution implementation of Karhunen Loéve expansion (KLE). Then, different operating modes of multi-state appliances were automatically classified utilizing a spectral clustering based method. Finally, using the total power demand profile, through a subspace component power level matching algorithm, the turned ON appliances along with their operating modes and power levels as well as the solar influx amount were found at each time point. The proposed NILM method was first successfully validated on six synthetically generated houses (with solar units) using real household data taken from the Reference Energy Disaggregation Dataset (REDD) - USA. Then, in order to demonstrate the scalability of the proposed NILM method, it was employed on a set of 400 individual households. From that, reliable estimations were obtained for the total residential solar generation and for the total load that can be shed to provide reserve services. Finally, through a developed prediction technique, NILM results observed from 400 households during four days in the recent past were utilized to predict the next day’s total load that can be shed.

Profil Perencanaan Karir Siswa Sekolah Menengah Kejuruan dengan Pemodelan Rasch Berdasarkan Jenis Kelamin

This research aimed to (1) perform inventory career planning of students, and (2) measuring students career planning based on gender. Data analysis used Rasch model for 45 students with actual power measurement 0.9272652. The research findings showed (1) inventory career planning has been fit with the theoretic model, and (2) female student have a tendency to a higher career planning rather than male student. In the future, to measurement of student’s career planning by using this inventory can only produce a high measurement information for students who have a mediocre ability. Further, the researcher need to consider to eliminate item No. 12 in this inventory due to the biased towards the male gender.

Deconstructing the Energy Consumption of the Mobile Page Load

Mobile Web page performance is critical to content providers, service providers, and users, as Web browsers are one of the most popular apps on phones. Slow Web pages are known to adversely affect profits and lead to user abandonment. While improving mobile web performance has drawn increasing attention, most optimizations tend to overlook an important factor, energy. Given the importance of battery life for mobile users, we argue that web page optimizations should be evaluated for their impact on energy consumption. However, examining the energy effects of a web optimization is challenging, even if one has access to power monitors, for several reasons. First, the page load process is relatively short-lived, ranging from several milliseconds to a few seconds. Fine-grained resource monitoring on such short timescales to model energy consumption is known to incur substantial overhead. Second, Web pages are complex. A Web enhancement can have widely varying effects on different page load activities. Thus, studying the energy impact of a Web enhancement on page loads requires understanding its effects on each page load activity. Existing approaches to analyzing mobile energy typically focus on profiling and modeling the resource consumption of the device during execution. Such approaches consider long-running services and apps such as games, audio, and video streaming, for which low-overhead, coarse-grained resource monitoring suffices. For page loads, however, coarse-grained resource monitoring is not sufficient to analyze the energy consumption of individual, short-lived, page load activities. We present RECON (REsource- and COmpoNent-based modeling), a modeling approach that addresses the above challenges to estimate the energy consumption of any Web page load. The key intuition behind RECON is to go beyond resource-level information and exploit application-level semantics to capture the individual Web page load activities. Instead of modeling the energy consumption at the full page load level, which is too coarse grained, RECON models at a much finer component level granularity. Components are individual page load activities such as loading objects, parsing the page, or evaluating JavaScript. To do this, RECON combines coarse-grained resource utilization and component-level Web page load information available from existing tools. During the initial training stage, RECON uses a power monitor to measure the energy consumption during a set of page load processes and juxtaposes this power consumption with coarse-grained resource and component information. RECON uses both simple linear regression and more complex neural networks to build a model of the power consumption as a function of the resources used and the individual page load components, thus providing benefits over individual models. Using the model, RECON can estimate the energy consumption of any Web page loaded as-is or upon applying any enhancement, without the monitor. We experimentally evaluate RECON on the Samsung Galaxy S4, S5, and Nexus devices using 80 Web pages. Comparisons with actual power measurements from a fine-grained power meter show that, using the linear regression model, RECON can estimate the energy consumption of the entire page load with a mean error of 6.3% and that of individual page load activity segments with a mean error of 16.4%. When trained as a neural network, RECON's mean error for page energy estimation reduces to 5.4% and the mean segment error is 16.5%. We show that RECON can accurately estimate the energy consumption of a Web page under different network conditions, such as lower bandwidth or higher RTT, even when the model is trained under a default network condition. RECON also accurately estimates the energy consumption of a Web page after applying popular Web enhancements including ad blocking, inlining, compression, and caching.

Enhanced Network Voltage Management Techniques Under the Proliferation of Rooftop Solar PV Installation in Low-Voltage Distribution Network

The proliferation of rooftop solar PV distributed generator (PVDG) installation in a low-voltage distribution network (LVDN) imposes voltage fluctuation challenges that are a threat to distribution system operators. Reactive power control (RPC) methods are insufficient in isolation to combat the overvoltage fluctuations manifested in an LVDN with a significant number of grid-tied PVDG installations, whereas active power curtailment (APC) control can alleviate the voltage fluctuation in such situations and it is achieved at the cost of reduced active power injection. This paper explores how deficiencies in both RPC and APC as separate approaches can be mitigated by suitably combining RPC and APC algorithms. Strategies combining two RPCs and one RPC in conjunction with APC are proposed as two coordinating algorithms by means of an instantaneous measurement of node voltage and active power. These coordinating algorithms are embedded in all the rooftop PVDG grid-tied inverters (GTIs), where the GTI coordinates among them for voltage support without exceeding individual inverter volt-ampere rating. The result of the combined approach shows a significant improvement in managing and stabilizing the voltage and allows the penetration of PVDG to be increased from 35.65% to 66.7% of distribution transformer kilovolt-ampere rating.

Active power measurement in arc welding and its role in heat transfer to the plate

A contemporary paper claimed that a method using the resistance of impedance (active power) for arc power calculation is more accurate than the conventional approach, with consequences on the actual heat transfer to the plate. However, despite the comprehensive reasoning, no heat-related results are shown in this intriguing paper to support the claim. Thus, the aim of this work was to apply the proposed method for determining the weight of active power in the total arc power. A series of weldments was carried out, by using GTAW in constant and pulsed current modes and short-circuiting GMAW with different inductance settings. The effect of the active power on the heat transfers to the plate was assessed by both bead cross-section geometries and calorimetry. The results showed that even a significant fraction of active power of the total power was reached, no changes in bead geometry or heat input were found. A review of the assumptions used in the primal paper showed that an arc is better represented by an ER circuit than by an RLC circuit. As a conclusion, the arc as a reactance-free load presents no component such as non-active power and the conventional approaches are accurate methods to measure arc power, representing the actual active power.

Expressing uncertainty of active power measurement by means of electrodynamic wattmeter

Expressing uncertainty of active power measurement by means of electrodynamic wattmeter

Residential Appliance Identification Based on Spectral Information of Low Frequency Smart Meter Measurements

A nonintrusive load monitoring (NILM) method for residential appliances based on uncorrelated spectral components of an active power consumption signal is presented. This method utilizes the Karhunen Loeve expansion to breakdown the active power signal into subspace components (SCs) so as to construct a unique information rich appliance signature. Unlike existing NILM techniques that rely on multiple measurements at high sampling rates, this method works effectively with a single active power measurement taken at a low sampling rate. After constructing the signature data base, SC level power conditions were introduced to reduce the number of possible appliance combinations prior to applying the maximum a posteriori estimation. Then, an appliances matching algorithm was presented to identify the turned-on appliance combination in a given time window. After identifying the turned-on appliance combination, an energy estimation algorithm was introduced to disaggregate the energy contribution of each individual appliance in that combination. The proposed NILM method was validated by using two public databases: 1) tracebase; and 2) reference energy disaggregation data set. The presented results demonstrate the ability of the proposed method to accurately identify and disaggregate individual energy contributions of turned-on appliance combinations in real households.

An Innovative Measurement Approach for Load Flow Analysis in MV Smart Grids

This paper proposes a novel measurement procedure for load flow analysis in medium voltage (MV) smart grids. The new approach is based on power measurements at low voltage (LV) side of MV/LV distribution substations. Such measurements are carried out by means of power quality analyzers. If compared with the load flow methods based on measurements at the MV side, the proposed approach has a lower cost and it offers an equally reliable measurement system. The proposed algorithm takes the basic concept of the current summation backward/forward method; some modifications are introduced to use LV load powers measurements. To this aim, the MV/LV power transformer is properly modeled and taken into account in the algorithm. The proposed approach is validated by means of both simulations and experimental measurements; the test system is the MV distribution grid of Ustica Island, Italy. First, the proposed algorithm is compared with the MATLAB/Simulink load flow tool, which is based on the traditional Newton-Raphson method. Second, a comparison is carried out between the proposed method and the measurement data collected in the actual MV network of Ustica. Such comparison takes into account the uncertainties of both proposed method, and experimental active and reactive MV power measurements.

Context-Based Energy Disaggregation in Smart Homes

In this paper, we address the problem of energy conservation and optimization in residential environments by providing users with useful information to solicit a change in consumption behavior. Taking care to highly limit the costs of installation and management, our work proposes a Non-Intrusive Load Monitoring (NILM) approach, which consists of disaggregating the whole-house power consumption into the individual portions associated to each device. State of the art NILM algorithms need monitoring data sampled at high frequency, thus requiring high costs for data collection and management. In this paper, we propose an NILM approach that relaxes the requirements on monitoring data since it uses total active power measurements gathered at low frequency (about 1 Hz). The proposed approach is based on the use of Factorial Hidden Markov Models (FHMM) in conjunction with context information related to the user presence in the house and the hourly utilization of appliances. Through a set of tests, we investigated how the use of these additional context-awareness features could improve disaggregation results with respect to the basic FHMM algorithm. The tests have been performed by using Tracebase, an open dataset made of data gathered from real home environments.

Non-intrusive load monitoring based on low frequency active power measurements

A Non-Intrusive Load Monitoring (NILM) method for residential appliances based on ac- tive power signal is presented. This method works e ectively with a single active power measurement taken at a low sampling rate (1 s). The proposed method utilizes the Karhunen Lo eve (KL) expan- sion to decompose windows of active power signals into subspace components in order to construct a unique set of features, referred to as signatures, from individual and aggregated active power signals. Similar signal windows were clustered in to one group prior to feature extraction. The clustering was performed using a modified mean shift algorithm. After the feature extraction, energy levels of signal windows and power levels of subspace components were utilized to reduce the number of possible ap- pliance combinations and their energy level combinations. Then, the turned on appliance combination and the energy contribution from individual appliances were determined through the Maximum a Pos- teriori (MAP) estimation. Finally, the proposed method was modified to adaptively accommodate the usage patterns of appliances at each residence. The proposed NILM method was validated using data from two public databases: tracebase and reference energy disaggregation data set (REDD). The pre- sented results demonstrate the ability of the proposed method to accurately identify and disaggregate individual energy contributions of turned on appliance combinations in real households. Furthermore, the results emphasise the importance of clustering and the integration of the usage behaviour pattern in the proposed NILM method for real households

On a Training-Less Solution for Non-Intrusive Appliance Load Monitoring Using Graph Signal Processing

With ongoing large-scale smart energy metering deployments worldwide, disaggregation of a household’s total energy consumption down to individual appliances using analytical tools, also known as non-intrusive appliance load monitoring (NALM), has generated increased research interest lately. NALM can deepen energy feedback, support appliance retrofit advice, and support home automation. However, despite the fact that NALM was proposed over 30 years ago, there are still many open challenges with respect to its practicality and effectiveness at low sampling rates. Indeed, the majority of NALM approaches, supervised or unsupervised, require training to build appliance models, and are sensitive to appliance changes in the house, thus requiring regular re-training. In this paper, we tackle this challenge by proposing an NALM approach that does not require any training. The main idea is to build upon the emerging field of graph signal processing to perform adaptive thresholding, signal clustering, and pattern matching. We determine the performance limits of our approach and demonstrate its usefulness in practice. Using two open access datasets—the US REDD data set with active power measurements downsampled to 1 min resolution and the UK REFIT data set with 8-s resolution, we demonstrate the effectiveness of the proposed method for typical smart meter sampling rate, with the state-of-the-art supervised and unsupervised NALM approaches as benchmarks. 1 1 Part of this work was presented at IEEE GlobalSIP-2015 [1] . The REFIT dataset used to generate the results can be accessed via DOI 10.15129/31da3ece-f902-4e95-a093-e0a9536983c4.

Measuring basic electrical quantities on the model of distribution line

In this paper, a practical laboratory exercise performed at the Laboratory for Electrical Engineering in the Higher Education Technical School of Professional Studies in Novi Sad, as an integral part of the subject Practicum is presented. The aim of the exercise is to introduce students to the phenomena of transfer of complex power along the distribution line, voltage drop, power losses, types of consumption, but also the methodology for the measurement and calculation of basic electrical quantities on the distribution line. The test network is a single-phase model of the three-phase low-voltage cable line. As a part of the exercise, measurements of voltage, current, active and reactive power and power factor are performed. The exercise analyzes the impact of X/R of the line and the type of consumption (resistive, resistive-inductive, resistive-capacitive, and motor) on the basic power system quantities.

Analysis of Smart Power Sockets Implementation

In this paper an analysis of implementation alternatives of smart electrical power sockets is presented. Smart socket (SSoc) functionality include power measurement, wireless connectivity, and load control. Power measurement uncertainty is defined by SSoc design and calibration. We investigate influence of voltage and current waveforms quantization errors and influence of Hall current sensor noise upon the active power measurement uncertainty. Voltage and current measurement module is calibrated by estimating corresponding gain factors using reference power analyser. Then calibration errors influence upon power measurement errors is studied. SSoc internal power dissipation is analysed by means of alternative power supply modules prototyping. DOI: http://dx.doi.org/10.5755/j01.eee.21.6.13754

Analysis of Smart Power Sockets Implementation

In this paper an analysis of implementation alternatives of smart electrical power sockets is presented. Smart socket (SSoc) functionality include power measurement, wireless connectivity, and load control. Power measurement uncertainty is defined by SSoc design and calibration. We investigate influence of voltage and current waveforms quantization errors and influence of Hall current sensor noise upon the active power measurement uncertainty. Voltage and current measurement module is calibrated by estimating corresponding gain factors using reference power analyser. Then calibration errors influence upon power measurement errors is studied. SSoc internal power dissipation is analysed by means of alternative power supply modules prototyping.DOI: http://dx.doi.org/10.5755/j01.eee.21.6.13754