Revenue Metering Research Articles

Enlightening Load Modeling by Means of Power Factor Decompositions

Considering the proliferation of power electronics applications and distributed energy resources, modern power grids are facing a significant increase in harmonic currents circulation and supply voltage deterioration, occasionally associated with small frequency variations. In such a context, the understanding of power phenomena in circuits with linear and non-linear loads under non-sinusoidal voltage conditions is nontrivial and still does not allow for an easy interpretation of harmonic sources, harmonic power flow or the identification of the parameters of a proper equivalent circuit. The main challenge is to develop modern theoretical approaches for load characterization, modeling, and parameter estimation so that new techniques can be formulated to provide adequate guiding for the analysis, compensation, revenue metering, accountability and other applications of power systems. Thus, based on the Conservative Power Theory (CPT) and further decomposition of its apparent power and power factor definitions, this paper proposes a novel methodology for estimating equivalent parameters and for proposing proper equivalent circuits capable of representing/modeling the main characteristics of single-phase generic loads (black boxes) and the related power phenomena in terms of passive dipoles (linear loads) or of harmonic voltage/current sources and their intrinsic transimpedances/transadmittances (non-linear loads). Simulation and experimental results were depicted to support and validate the proposed approach, showing that it might be a powerful modeling technique to represent generic loads in a modern power grid scenario, while being used for complex applications such as reactive power compensation or accountability in circuits with nonlinear loads and distorted voltages.

In Situ Calibration of Transmission System Power Grid Energy Meters Using Energy Measurements and Kalman Filter

Correct energy measurement is vital for electric energy trading. There are often stringent legal demands on the revenue metering that require periodic in situ substation verification. Traditional energy metering testing methods are not possible in IEC 61850 digital stations using a process bus. In this article, we will show that it is possible to use data analysis to verify the accuracy of energy measurement systems in substations. Our algorithms can be used as a part of the legal verification and runs remotely on-line. As a consequence, some of the periodic accuracy verification including substation visits can be abandoned. The on-line algorithms makes it possible to decrease the errors in both revenue metering systems and in other energy measurements systems in the Swedish transmission system. Measurement errors are now detected and amended much faster which reduces incorrect billing. The estimated value of incorrect billing is decreased by more than a million EUR annually. Our algorithms also provide a solution to bridge the problem to verify measurements in future fully digital substations.

New approaches and digital technology automation tasks processes of control and accounting of electricity in distribution networks

This paper studies 0.4 kV power distribution networks (PDN) and automated systems for electricity monitoring and metering (ASEMM) As is known, one of the main tasks of ASEMMs is the digitalization of PDNs, aimed at further improving the efficiency and reliability of their operation. It is advisable that new models, methods, and intelligent technologies used for automation and informatization of distribution networks should also be focused on minimizing their power losses, which are currently fairly high thus significantly compromising the technical and economic performance of automation systems employed and PDNs. Modern (conventional) ASEMMs, implemented at the facilities of utilities, do not have the appropriate technical, algorithmic, and software tools designed to reduce power losses in the PDN. This is due to the fact that conventional ASEMMs mainly solve the problem of remote data collection from the system meters and their digital processing for the purpose of revenue metering of electricity. In this regard, the paper proposes methodological, algorithmic, and digital technologies designed to solve a set of new functional tasks in the conventional ASEMMs, aimed at reducing power losses in DPNs by optimizing their operating conditions.

Revenue Metering of Unbalanced Prosumers in Energy Communities

The presence of power generating plants owned by prosumers may lead to unbalanced bidirectional energy flows at the points of connection to the relevant distribution systems. This will impact future energy communities, where appropriate metering within the community is a crucial issue for billing purposes. This paper shows that the current metrics for active energy measurement and the registration of three-phase revenue meters may fail to fairly charge unbalanced prosumers for their use of the distribution system as an inherent phase-to-phase balancer. On the other hand, it is proven here that adopting metrics based on positive sequence power/energy measurement would lead to more fair billing within the community. A comparative study was performed using a simplified but realistic model of a distribution system feeding two prosumers (i.e., an archetype of an energy community). First, representative case studies were considered. Then, a more realistic simulation of a single day of operation was conducted. The main contribution of the paper is a detailed and systematic comparison of the methods used for measuring and sorting energy into registers in revenue meters to support the ongoing discussions about fair metering within future energy communities.

Development Issues of Systems for Automation and Digitalization of Power Distribution Networks

This paper studies 0.4 kV power distribution networks (PDNs) and automated systems for electricity monitoring and metering (ASEMM). As is known, a main task of ASEMMs is to digitalize PDNs, which is aimed at improving the efficiency and reliability of their operation. It is advisable that new models, methods, and intelligent technologies used for automation and informatization of distribution networks should also be focused on minimizing their power losses, which are currently fairly high and significantly compromise the technical and economic performance of automation systems employed and PDNs. Modern (conventional) ASEMMs, implemented at the facilities of utilities, do not have the appropriate technical, algorithmic, and software tools to reduce power losses in the PDN. This is due to the fact that conventional ASEMMs mainly collect remote data from the system meters and ensure their digital processing for the purpose of revenue metering of electricity. In this regard, the paper proposes methodological, algorithmic, and digital technologies to accomplish a set of new functional tasks in the conventional ASEMMs, aimed at reducing power losses in PDNs by optimizing their operating conditions.

Current-Sensing Techniques for Revenue Metering and for Detecting Direct Current Injection from Electric Vehicles: A Review

Current-Sensing Techniques for Revenue Metering and for Detecting Direct Current Injection from Electric Vehicles: A Review

Integrated Electric Vehicle Shunt Current Sensing System for Concurrent Revenue Metering and Detection of DC Injection

Certified electric vehicle power converters can inject DC current into the AC grid if they fail. Verification of DC injection by electric vehicle supply equipment can be a cost-effective extra measure to ensure power quality from a variety of plugged-in electric vehicles. As electric vehicle supply equipment typically performs high-accuracy revenue energy metering, we propose that measurement of AC current and DC injection with a single sensor is the most economically efficient design. This article presents an integrated shunt current sensing system with separation of AC and DC signals for concurrent revenue metering and DC injection detection. It also shows how the combined sensor is integrated into 19.2 kW single-phase electric vehicle supply equipment, and outlines how the design would be extended to 100 kW three-phase electric vehicle supply equipment. The prototype can detect DC injection of ≥400 mA in an AC current up to 80 A in accordance with the IEEE 1547-2018 standard. The prototype can also conduct revenue metering within the 1.0 accuracy class. The prototype does not have high power dissipation at high currents typical for shunt systems. Finally, the prototype is less costly than common electric vehicle supply equipment revenue metering CT systems with the addition of the popular Hall-effect sensor.

원자력발전소 변압기 연결 선로 결상 검출 시스템

On January 30, 2012 an auxiliary component of Byron Unit 2 was tripped on bus under voltage. The cause of the event was the failure of the C-phase insulator track for the Un it 2 station auxiliary transformer(SAT) revenue metering transformer. In addition to this event, other events have occurred at other plants resulting in an open-phase condition.(1) Therefore, Nuclear Regulatory Commission(NRC) has requested tha t not only nuclear power plant(NPP) operating company but also its Design Certification(DC) applicant have to prepare open-phase detecting system in their operating plants and design document. In this paper, various open-phase conditions are simulated in NPP using Electromagnetic Transient Program(EMTP) and Atpdraw, and open-phase condition detecting system is proposed for Main Transformer(MT), Unit Auxiliary Transformer(UAT) and SAT connected power line in NPP.

Measurement Infrastructure to Support the Reliable Operation of Smart Electrical Grids

Grid operators are facing a significant challenge in ensuring continuity and quality of electricity supply, while more and more renewable energy sources are connected to the grid. The resulting evolvement of so-called smart grids strongly relies on the availability of reliable measurement data for monitoring and control of these grids. This paper presents an overview of the results achieved in recent smart grid metrology research in Europe, aiming to realize the required metrology infrastructure for ensuring security and quality of supply in future smart electrical grids. A consortium of 22 metrology and research institutes has made significant steps in modeling of smart grids, enhancement of the revenue metering infrastructure, performance and evaluation of onsite power quality campaigns, and the development of a metrological framework for traceability of smart grid phasor measurements.

Catering Revenue Metering System and its Application

Revenue metering is one of the most important profit growth modes in services. This paper study the issue based on the Analytical Hierarchy Process (AHP) analyzes, the results show that the revenue metering constitute indicators of the degree of impact on revenue metering, its from the index layer constituting hotel revenue metering to explore the impact of the implementation of the effect of a short board, to establish a perfect hotel revenue metering system to provide a more reliable basis and achieve the desired results.

Load Characterization and Revenue Metering Under Non-Sinusoidal and Asymmetrical Operation

This paper proposes an approach to load characterization and revenue metering, which accounts for the influence of supply deterioration and line impedance. It makes use of the Conservative Power Theory and aims at characterizing the load from the measurements done at the point of common coupling. Despite the inherent limitations of a single-point measurement, the proposed methodology enables evaluation of power terms, which clarify the effects of reactivity, asymmetry and distortion, and attempts to depurate the power consumption accounted to the load from those terms deriving from supply nonidealities.

Accountability in Smart Microgrids Based on Conservative Power Theory

Smart microgrids offer a new challenging domain for power theories and metering techniques because they include a variety of intermittent power sources which positively impact on power flow and distribution losses but may cause voltage asymmetry and frequency variation. In smart microgrids, the voltage distortion and asymmetry in presence of poly-phase nonlinear loads can be also greater than in usual distribution lines fed by the utility, thus affecting measurement accuracy and possibly causing tripping of protections. In such a context, a reconsideration of power theories is required since they form the basis for supply and load characterization. A revision of revenue metering techniques is also suggested to ensure a correct penalization of the loads for their responsibility in generating reactive power, voltage asymmetry, and distortion. This paper shows that the conservative power theory provides a suitable background to cope with smart grids characterization and metering needs. Simulation and experimental results show the properties of the proposed approach.

Computer-Controlled System for Calibrating High-Voltage Revenue Metering Equipment Under Actual Operating Conditions

The development of a computer-controlled current-comparator-based test system for calibrating high-voltage revenue metering equipment under actual operating conditions of high voltage/high current with sinusoidal or nonsinusoidal voltage and current waveforms is described. Measurements can be made at any power factor from zero lead or lag through unity, at line-to-ground voltages up to 100 kV and currents up to 2000 A. The magnitude and phase uncertainties (k = 2) of the new calibration system are estimated to be not more than 100 μW/VA and 100 μrad, and 200 μW/VA and 200 μrad for sinusoidal and nonsinusoidal conditions, respectively. The calibration system can be used in the laboratory or on-site in high-voltage substations.

Optical High-Voltage Sensor Based on Fiber Bragg Grating and PZT Piezoelectric Ceramics

Electric power facilities, such as substations, rely on voltage transformers (VTs) for measurement and protection. These pieces of equipment are bulky and heavy and tend to explode, destroying nearby equipment and posing a threat to substation personnel. Optical voltage transducers offer many improvements on traditional inductive and capacitive VTs, such as linear performance, wider dynamic range, lighter weight, smaller size, and improved safety. This paper relates to the development of a high-voltage sensor system using a PZT piezoelectric crystal as a transducer and a fiber Bragg grating as a sensor for an optical VT for a 13.8-kV class. The results show that the developed sensor is capable of attaining the International Electrotechnical Commission 0.2%-accuracy class for the revenue metering system.

ELECTRIC TRACTION ENERGY METERING ON GERMAN RAILWAYS AND THE IMPACT OF EUROPEAN STANDARDIZATION ON THE ENERGY BILLING PROCESS IN GERMANY

With the onset of liberalization of energy markets and the formation of DB Energie Inc. as a wholly owned subsidiary of Deutsche Bahn AG (German Railways), proper billing of electric energy to railway-based consumers has become an important issue. Hence, DB Energie had to develop and implement a revenue metering scheme for traction energy consumed by railroad vehicles. The impact of international interoperable traffic is considered in this paper.

About the accuracy of some proposed procedures for revenue metering under non‐sinusoidal unbalanced conditions

AbstractIn order to discourage the insertion of polluting loads, suitable tariff policies should be adopted. A possible strategy is based on the comparison between the total active power and the active power at fundamental frequency and positive sequence. Digital Signal Processing techniques allow for the implementation of revenue meters able to measure both those quantities and any index based on them. This paper analyses the accuracy that can be expected in the measurement of both the ratio and the difference of the above powers. The results of numerical simulations confirm that the ratio measurement is suitable for revenue purposes even when the total and fundamental active powers differ for parts per thousands.

US utility revenue metering markets will make $3.1 billion in 2002

US utility revenue metering markets will make $3.1 billion in 2002

Revenue metering error caused by induced voltage from adjacent transmission lines

A large zero sequence voltage was found to have been induced onto a 138 kV line from adjacent 500 kV lines where these share the same transmission right-of-way. This zero sequence voltage distorted the 2 1/2-element revenue metering schemes used for two large industrial customers supplied directly from the affected 138 kV line. As a result, these two customers were overcharged, on average, approximately 3.5% for 15 years. A description is presented of the work done to trace the origins of the zero sequence voltage, quantify the metering error, and calculate customer refunds which, in the end, totaled $4 million.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Polyphase apparent power and power factor under distorted waveform conditions

It is pointed out that the term apparent power does not have a unique meaning when used to describe polyphase, nonsinusoidal systems; in a general case it is an artificial concept with no physical interpretation. It is shown that this ambiguity can have implications for power factor calculations, reactive current compensation, and revenue metering. The time-domain based method of defining and measuring the apparent power is discussed. The necessity of a critical revision of terms relating to apparent power in the IEEE Standard Dictionary is pointed out.< <ETX xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">&gt;</ETX>

Optical voltage and current sensors used in a revenue metering system

The authors discuss the development of an optical voltage sensor as part of an all optical sensor based revenue metering system. The magnetooptic or Faraday effect was used to implement a magnetooptic voltage transducer (MOVT) to measure voltage by sensing the current flow through a capacitor connected from a 161 kV transmission line to ground. The current sensor was a magnetooptic current transducer (MOCT) developed previously. The design of the voltage sensors using the magnetooptic effect allows the implementation of a revenue metering system using all optical sensors. This method of measuring voltage was previously unproven. The components of the all optical sensor revenue metering system, the site installation, and the data acquisition system used to monitor the system are described. Decisions leading to the design of the MOVT are discussed. >