A New Methodological Approach to Quality Assurance of Energy Meters Under Nonsinusoidal Conditions (original) (raw)
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Electric energy meters are designed to account energy under sinusoidal and nonsinusoidal conditions, because both, old and new standards for energy meters require testing their accuracy under different conditions. The latest EN 50470 standard increases the range of meter testing under nonsinusoidal conditions, introducing new shapes of test signals such as the phase fired waveform or the burst fired waveform. This paper discusses calibration problems of electronic revenue energy meters for direct connection and for connection through current transformers, and it proposes a new calibration procedure which reproduces normal operating conditions better: three-phase configurations of measurement systems, load range during meter testing or shapes of test signals. Recently, modern Electrical Power Standards, also known as Power Calibrators, enable automatic testing of various types of electrical devices, including electricity meters in their normal operating conditions. This article prese...
A METHODOLOGY FOR QUALITY ASSURANCE IN ENERGY MEASUREMENTS UNDER NON-SINUSOIDAL CONDITIONS
The evaluation of the electrical energy flows is at the base of all operations connected to the commercial transactions in energy market. The assessment of "metrological quality" of the power/energy measuring apparatuses is well establishes in ideal sinusoidal conditions. But, with increasing diffusion of power electronics the typical characteristics of power network are far from sinusoidal one. In this paper a new methodology for quality assurance of energy meters in non sinusoidal operating conditions is reported. The description of methodology and some experimental results obtained are discussed in detail.
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Electric energy meters have always been designed to account energy under sinusoidal conditions, and therefore, the uncertainty specification outside these conditions was of little interest. This was considered acceptable when the voltage and current distortion level was low and the old well-known induction meters were used. In fact, under these conditions, the measurement errors caused by distortion did not generally penalize the customers. The present situation is, however, quite different: Distortion is not any longer negligible, particularly in low-voltage systems, and the modern electronic energy meters can be much more sensitive to distortion than the induction meters, depending on the implemented measurement algorithm. This paper briefly discusses the calibration problems raised by the electronic energy meters and proposes a new calibration procedure, fully compliant with the recent Directive of the European Parliament on the measuring instruments, and based on a synthesizer of randomly distorted signals, capable of evaluating the measurement uncertainty of the energy meters under the distorted conditions that are likely to be met in their normal operating conditions. Index Terms-Calibration procedure, electric energy metering, nonsinusoidal conditions.
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The measurement of the electrical energy and its billing for tax purpose are of great relevance. In spite of its importance, in the past a scarce attention was given to issues as the calibration and the traceability of the electrical energy meters, so that, at least in Italy, more than 30 millions of energy meters operate and put a tariff without proper metrological characterization. This situation is caused by both the absence of specific laws and the high cost related to the traceability process. In this ambit, a new European Directive on measuring instruments (MID) was introduced in 2004 with the aim of providing a high level of metrological protection in order that any party affected can have confidence in the result of measurement. In Italy the MID was adopted by a legislative decree and imposed that: (i) each active electrical energy meter put into service has to be kept in test for a period for verifying its operating; (ii) after the test period, with positive result, the meter has to be calibrated at least twice in the year. The paper proposes a discussion about the issues of active electrical energy meter calibration and the analysis of requirements of the MID. Finally, the design of a device that may solve the problem of the traceability to national standards in easy and economic way is reported.
Testi G of e Ergy Meters U Der Three-Phase Determi Ed a D Ra Dom O Si Usoidal Co Ditio S
Electric energy meters are designed to account energy under sinusoidal and nonsinusoidal conditions, because both, old and new standards for energy meters require testing their accuracy under different conditions. The latest EN 50470 standard increases the range of meter testing under nonsinusoidal conditions, introducing new shapes of test signals such as the phase fired waveform or the burst fired waveform. This paper discusses calibration problems of electronic revenue energy meters for direct connection and for connection through current transformers, and it proposes a new calibration procedure which reproduces normal operating conditions better: three-phase configurations of measurement systems, load range during meter testing or shapes of test signals. Recently, modern Electrical Power Standards, also known as Power Calibrators, enable automatic testing of various types of electrical devices, including electricity meters in their normal operating conditions. This article prese...
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Currently, there are two energy meters types installed: electromechanicals and electronics. The first ones are still the most frequent. However, new facilities tend to use electronics energy meters based on solid-state technology. Electromechanicals devices present characteristics already well known that allows us to measure only energy consumption. However, now the rules that manage the energy supply are totally new, there is a competitive electricity market. This way, detailed information on the energy consumption of each client is needed. In this point, electronic meters seem to be the best option to face the new challenges. This study will review the operating principles of solid-state energy meters. The behavior of some three phases models under nonsinusoidal conditions is studied. Experimental setup and test methodology are discussed as well.
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Due to rapid advancements in power electronics, the utilization of electronically switched loads and nonlinear loads is increasing gradually in the electrical power system. These loads create problems of measuring instruments, when connected to the power distribution systems. In this paper, an experimental investigation has been carried out to analyze the performance of single-phase watt-hour (induction and electronic types) energy meters that are being used in Pakistan. The accuracy of the energy meters has been tested under different household nonlinear loads, at various power factors and also at different supply voltage levels. Power factor and total harmonic distortion (THD) of different household loads are also recorded in the experimental work. A hardware based experimental setup has been designed to perform the experimental work. The experimental results have been compared to Water and Power Development Authority (WAPDA) standards for energy meters.
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