Energy meter behaviour under non-sinusoidal conditions

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

Design and implementation of a modified fourier analysis harmonic current computation technique for power active filters using DSPs

The design and implementation of a harmonic current computation technique based on a modified Fourier analysis, suitable for active power filters incorporating DSPs is presented. The proposed technique is suitable for the monitoring and control of load current harmonics for real-time applications. The derivation of the basic equations based on the proposed technique and the system implementation using the Analogue Devices SHARC processor are presented. The steady state and dynamic performance of the system are evaluated for a range of loading conditions

Measurement of Passive R, L, and C Components Under Nonsinusoidal Conditions: The Solution of Some Case Studies

This paper deals with the measurement of the R, L, and C parameters of passive components in nonsinusoidal conditions. Since these components usually work with voltage and current waveforms that are different from sinusoidal ones, nonsinusoidal characterization has to be made. The importance of nonsinusoidal characterization of passive components is highlighted through the analysis of two case studies: (1) the influence of distorted waveforms on the line impedance stabilizer network (LISN) passive component behaviors and (2) the influence of voltage and current harmonics on hybrid filter responses. In this paper, the authors propose and describe a measurement method based on linear system identification and model parameter estimation techniques. Then, the two case studies are analyzed and described with the help of some test results

Energy flow in nonlinear circuits

Apparent power and reactive power are two critical quantities in energy flow studies in electrical power systems. Existing definitions for these terms work well when both voltages and currents are sinusoidal with respect to time. However, both apparent and reactive power have no physical meaning. When these physically unclarified quantities are applied to non-sinusoidal systems, the following questions related to power flow remain not fully answered to date. What do these quantities really mean? Is it fair to bill customers based on the measurement of physically not meaningful quantities? What is the efficient way, both economical and technical, to compensate non-active power in power networks?;To answer the above mentioned questions, this thesis analyzes energy flow in nonlinear circuits, clarifies and proposes new power quantities with physical interpretations that are practical and effective when voltages and/or currents are non-sinusoidal. The suggested definitions are measurable quantities based on time-domain approach, and are useful in evaluating the power quality and efficiency in electrical systems. The measurement method and compensation with active filters are also discussed

Iron Losses Prediction with PWM Supply Using Low and High Frequency Measurements: Analysis and Results Comparison

In this paper, two different methods for iron loss prediction are analyzed. The first method is based on the classical separation of loss contributions (hysteresis, eddy-current, and excess losses). The model requires loss contribution separation using iron loss measurements with sinusoidal supply. In this paper, this method will be called the ldquolow-frequency method.rdquo The second method, named the ldquohigh-frequency method,rdquo is based on the assumption that, under pulsewidth modulation supply, the higher order flux density harmonics do not influence the magnetic work conditions. These magnetic conditions depend only on the amplitude of the fundamental harmonic of the flux density. In this paper, both the proposed methodologies and the related measurements are described in detail, and the obtained results are compared with the experimental ones. The experimental results show that both methods allow getting excellent results. The high-frequency method is better than the lower one but requires a more complex test bench. Depending on the accuracy required by the user, the more handy method can be chosen, with the guarantee that the estimation errors will be lower than 5

Merenje komponenti električne snage po standardu IEEE 1459-2010

Merenje u nesinusoidalnim uslovima je u centru istraživanja i mnogo se napora ulaže da se pojam reaktivne snage star više od sedamdeset godina definiše na nov način. Postoji niz pristupa rešavanju problema definisanja snaga i/ili pokušaja koncipiranja merne instrumentacije za merenje snaga u sistemima naizmenične struje pod nesinusoidalnim uslovima. Jedini standard koji se odnosi na specifične zahteve za tačnost i odgovarajuće uslove testiranja u prisustvu harmonijskih izobličenja je IEEE Std. 1459-2010, koji ne daje definiciju reaktivne snage u nesinusoidalnim uslovima. Koncept ovog IEEE standarda je baziran na raz-dvajanju snage na fundamentalni i nefundamentalni deo. U literaturi su prisutne različite tehnike za imple-mentaciju standarda IEEE Std. 1459-2010. Ovaj standard je implementiran pomoću dva osnovna prilaza: (1) dvostepeni algoritam sa estimacijom harmonijskih spektara naponskog i strujnog signala u prvom koraku i računanjem nepoznatih komponenti snage u drugom koraku i (2) filterska implementacija kombinovana sa Clarke-Park transformacijom u slučaju trofaznog sistema. U radu je prikazana nova metoda za merenje električnih veličina definisanih standardom IEEE 1459-2010 koristeći drugi pristup. Ključni elementi su adaptivni pojasni i niskopropusni FIR filteri koji izdvajaju fundamentalnu i jednosmernu komponentu. U radu su korišćene tehnike oversemplinga i decimacionih filtera, čime se izbegavaju problemi vezani za osetljivost na zaokruživanje koeficijenata FIR kaskadnih filtera velikog reda, smanjuje obim numeričkih računanja i povećava tačnost merenja. Estimacija simetričnih komponenti vrši se pomoću matrice adaptivnih faznih korektora. U cilju procene performansi algoritma izvršene su računarske simulacije i dati njihovi rezultati.In this paper, the design and implementation of a novel recursive method for the power measurement ac-cording to the IEEE Standard 1459-2010 have been described. The most important parts are adaptive band and low-pass FIR filters that extract fundamental and dc components, respectively. In addition, by using oversampling techniques and decimation filters, coefficient sensitivity problems of the large-order FIR comb cascade structure are overridden and the parameter estimation accuracy is improved. The symmetrical components are estimated through a transformation matrix of adaptive phase shifters. The effectiveness of the proposed techniques is demonstrated by simulation results

Random Generation of Arbitrary Waveforms for Emulating Three-Phase Systems

This paper describes an apparatus for generating a signal representative of steady-state and transient disturbances in three-phase waveforms of an ac electrical system as described in IEEE Std 1159-09. It can be configured as a synthesizer of randomly distorted signals for different applications: for testing the effects of disturbed grid on equipment and to generate patterns of electrical disturbances for the training of artificial neural networks, which are used for measuring power quality tasks. For the first purpose, voltage and current amplifiers are added in the output stage, which allows the generation of disturbed signals at grid level.Comisión Interministerial de Ciencia y Tecnología DPI2006-15467-C02-01Comisión Interministerial de Ciencia y Tecnología DPI2006-15467-C02-0