bluuebunny/crossref_metadata_2025_split huggingface dataset:
Feedforward torque control of a switched reluctance motor based on static measurements
Authors: Bausch H. , Kanelis K. 
Published: July 2010

AbstractA model of the non‐linear switched reluctance motor (SRM) has been developed that provides an analytical representation based on static measurements of the flux linkage by simple polynomial functions. Using an approximation of the Φ(i)‐characteristic with the rotor position angle γ as parameter it is possible to calculate the dynamic performance of the drive in the whole torque‐speed range. Depending on the torque command Tw the switching angles γO (“on”) and γc (“off”) are determined with minimum ohmic losses under the assumption of a constant supply voltage. For the ease of demonstration the results are restricted to the field weakening range. It turns out that the switching angles are parabolic functions of the torque with the well‐known tendency for advance‐shifting at increasing speed. The calculated current waveforms and average torque values coincide well with those measured at the test drive.
The real confidence intervals in state estimation
Authors: Al‐atwan A. , Koglin H.‐J. 
Published: July 2010

AbstractThe computation of the confidence intervals has been proposed in this paper. Two methods are developed for this purpose. In the first method the confidence intervals are evaluated by calculating the variance of the estimation errors, the differences between the true and the estimated values. While in the second method, the confidence intervals are evaluated depending on the up‐to‐date results of the state estimation. Both methods are tested using a measuring system for the IEEE‐14‐Bus‐Test‐Network with the aid of the Monte‐Carlo‐Simulation‐Technique.
Description of power electronic circuits by block diagrams
Authors: Tuttas C. 
Published: July 2010

AbstractPower electronic circuits are non‐linear dynamic systems. Until now, it is not usual to describe these systems by block diagrams. In this paper a new model for power electronic switches is proposed. The semiconductor devices are represented by voltage and current sources. Due to this modelling block diagrams of power electronic circuits can be drawn. These block diagrams give an insight into the dynamic behaviour of power electronic systems.
Damping of common‐mode torsional oscillations using a modified NGH SSR damping scheme
Authors: Wang L. 
Published: July 2010

AbstractThis paper presents the analyzed results on the application of a modified NGH SSR damping scheme for damping common‐mode torsional oscillations that occur in a power systems containing series‐capacitor compensation. The IEEE Second Benchmark Model, system‐2, which has two non‐identical turbine‐generator sets connected to an infinite bus through a series‐capacitor compensated transmission line, is employed to investigate the possible unstable subsynchronous resonance (SSR) which can be suppressed by the proposed damping scheme. A unified approach based on modal control theory is employed to design damping controllers for the modified NGH SSR damping module. Frequency‐domain approach based on eigenvalue analyses such as different operating conditions and stable regions on RE‐Xc plane is performed. Time‐domain approach based on non‐linear model simulations under a severe three‐phase short‐circuit fault at infinite bus is also carried out. It can be concluded from the simulation results that the proposed modified NGH SSR damping scheme incorporated with the designed damping controllers can effectively suppress the common‐mode torsional oscillations.
400‐kV‐network harmonic impedance evaluation from harmonic distortion measurements at the RFX site
Authors: Bettini P. , De Lorenzi A. 
Published: July 2010

AbstractThe lack of knowledge of the harmonic frequency behaviour of the extra‐high‐voltage (EHV) transmission network prevents the possibility to choose, at the design stage, an appropriate system for harmonic mitigation for current harmonic source loads directly fed by the transmission network, as well as arc furnaces and facilities for thermonuclear fusion researches. The paper describes the methodology employed to determine the harmonic network impedance from current and voltage measurement seen at the Camin‐Padova node of the Italian transmission network, in which are injected the current harmonics produced by the reversed field pinch experiment (RFX) fusion facility; in particular, a simple method for precise measurement of voltage harmonics is presented in detail.
Proposal of a new method for controlling the torque and the flux of a voltage source inverter‐fed induction motor
Authors: Amin B. 
Published: July 2010

AbstractIn this paper, a method for controlling the torque and the flux of an induction motor is presented. It consists in calculating, within each time‐step, appropriate values of the voltage to be impressed across the phase windings. The method takes into account the effects of the magnetic saturation, as well as those of the variations of the rotor and stator resistances versus the temperature. It does not require any integrators for evaluating the stator‐flux and works under controlled commutation frequencies.
Electrode‐fall voltages of SF6 and air arcs between electrodes of Fe, W, Cu‐W, Cu and Ti in the current range from 10 A to 20 kA
Authors: Yokomizu Y. , Matsumura T. , Henmi R. , Kito Y. 
Published: July 2010

AbstractMeasurements were made of the sum of cathode‐fall and anode‐fall voltages, i .e. electrode‐fall voltage Ufall for SF6 and air arcs at a pressure of 0. 1 MPa in a wide current range from 10 A to 20 kA. The arcs were burned between electrodes of iron, tungsten, copper‐tungsten, copper and titanium. For each electrode, Ufall atagiven current was estimated as the arc voltage at the zero gap length between the electrodes, which was extrapolated from arc voltages measured in short gaps with lengths below 3 mm. The electrode‐fall voltage Ufall of the SF6 arc proved to be 17.5 V, 13.8 V, 17.5 V, 17.5 V and 17.3 V for the Fe, W, Cu‐W, Cu and Ti electrodes, respectively. The electrode‐fall voltage Ufall was affected by the electrode material, while Ufa u of the air arc is almost the same as that of the SF6 arc. It was also found that Ufall of each arc at a given electrode was independent of current in the above range.
Active power filter for harmonic and reactive power compensation in three‐phase, four‐wire systems supplying non‐linear loads
Authors: Singh B. , Ai‐Haddad K. , Chandra A. 
Published: July 2010

AbstractAn active power filter (APF) is proposed which eliminates harmonics, compensates reactive power and neutral current in a three‐phase four‐wire electric system supplying non‐linear loads. An insulated‐gate‐bipolar‐transistor (IGBT)‐basedpulse‐width modulation (PWM) voltage source inverter (VSI) with a DC bus capacitor is employed as an APF. A hysteresis‐rule‐based carrierless PWM current control technique is used to generate switching signals to the devices of the APF. Three single‐phase diode rectifiers supplying resistive‐capacitive loads are considered as a three‐phase non‐linear load. A detailed dynamic model of the scheme is developed to study transient and steady‐state behaviour of the APF. The proposed APF is found capable to compensate reactive power, neutral currents and to reduce the harmonics below specific recommendations of IEEE‐519 standard.
Complete symbolic factorization for the security analysis of power systems
Authors: Berizzi A. , Piovan U. , Silvestri A. , Zaninelli D. , Pavani R. 
Published: July 2010

AbstractIn modern power systems, it is more and more important to assess in a very short time the security of the system, checking the ability of the network to sustain possible contingencies. The paper presents a symbolic approach to an efficient implementation of the factorization, applied to the well‐known Cholesky factorization, that turns out to be useful especially when there is the need to factorize several matrices with the same sparsity structure, as in case of security studies.
New approach to the calculation of electrical transients, Part I: Theory
Authors: Bijl N. , Van Sluis L. Der 
Published: July 2010

AbstractThe calculation of electrical transients in power systems is important for insulation coordination. Most of the compiiter programs in current use are based on the nodal admittance method. This paper describes a computer program for the calculation of electrical transients based on a new approach which enables the use of more sophisticated numerical integration routines. The program can cope with linear network elements like resistors, capacitors, reactors, voltage and current sources and also with non‐linear network elements like surge arresters and arc models. The description of the models and their parameters is stored in libraries separate from the main program. The user can define his own models.
Definitions of electrical quantities commonly used in non‐sinusoidal conditions
Authors: Ferrero A. 
Published: July 2010

AbstractThe analysis of electrical systems under non‐sinusoidal conditions has become an important topic in electrical engineering. Most of the approaches to the analysis and operation of electrical systems are undergoing a thorough revision, and several contributions concerning these topics can be found in the recent literature. However, in the development of this matter problems occur because of misunderstanding and misinterpretation mainly due to the terminology used by individual authors when referring to identical concepts and quantities. The present contribution considers the definitions of quantities that are frequently used for the analysis of non‐sinusoidal systems and formulates a technical‐scientifically sound document where these quantities and concepts are defined, a technical sound name is given, and a symbol is proposed for each quantity.
Hyper space vectors: A new four‐quantity extension of space‐vector theory
Authors: Depenbrock M. , Staudt V. 
Published: July 2010

AbstractThe space‐vector theory, which allows to describe three linearly dependent quantities (e. g. three voltages or three currents) using only two linearly independent quantities represented in an orthonormal coordinate system, is widely used in the fields of AC machine theory, power definitions and active filtering. It can be used very effectively in case of circuits with only three terminals. Problems occur in case of four terminals, when four linearly dependent quantities (e. g. four currents, the sum of which is always zero) exist. In this case a zero‐sequence quantity can be additionally introduced, which has to be treated separately with special equations. Vector operations like cross product or dot product, which are very useful to calculate e. g. power quantities, can no longer be used in the general case. This paper presents a method transforming any system represented by four linearly dependent quantities or by three linearly independent quantities into a three‐dimensional orthonormal coordinate system. All four members of a set of linearly dependent quantities are treated equally. We suggest to call this representation Hyper Space Vector (HSV). A lot of vector operations can be applied without problems to HSV, making calculations much easier and more graphic.
Assessment of electric power quality: Indices for identifying disturbing loads
Authors: Muscas C. 
Published: July 2010

AbstractThe study aimed at defining parameters capable of assessing, in terms of distortion and unbalance, the quality of the electric power drawn by the customer. Taking as a starting point the advantages and limitations of the methods proposed so far in the literature, two new indices are introduced, useful for quantifying the disturbing characteristics of a load. The efficiency of these indices has been assessed by computer simulations to assess the applicability of the method to three‐wire and four‐wire three‐phase systems in many realistic situations.
Synthesis of pseudo‐balanced three‐phase line configurations
Authors: Faria J. A. Brandāo 
Published: July 2010

AbstractIn analysing lossy three‐phase line overhead configurations it is commonly believed that the well‐known example of a perfectly transposed line is the only and single example of a balanced configuration. It is shown that this is a mistake. Conditions are established and a procedure is developed for synthesizing balanced un‐transposed line configurations. Concrete examples illustrating such configurations are presented.
Harmonic blocking compensator: Frequency properties
Authors: Hsu S.‐M. , Czarneeki L. S. 
Published: July 2010

AbstractResonant harmonic filters (RHF) commonly used for reducing waveform distortion in distribution systems have a number of disadvantages. Their effectiveness degrades with an increase in the distortion of the distribution voltage. The current harmonics other than those to which the filter is tuned can be amplified. Filter performance is very sensitive, usually, to reconfigurations in the distribution system. Active harmonic filters are alternative for RHF. They have high complexity, however, and their dissemination in distribution systems seems to be rather slow. This paper investigates another alternative for RHF, namely a harmonic blocking compensator (HBC) built of a shunt capacitor and a series resonant link tuned to the fundamental frequency. This paper compares properties of RHF and HBC, provides fundamentals for the design of HBC and illustrates their properties with results obtained with a laboratory prototype.
System impedances and background noise in the frequency range 2 kHz to 9 kHz
Authors: Gretsch R. , Neubauer M. 
Published: July 2010

AbstractA one year research effort was launched to investigate the internal impedances and coupling impedances within the public low‐voltage network in the frequency range from 2 kHz to 9 kHz. At 250 different nodes, roughly 6000 impedance measurements were carried out. In this paper, the measurement method and the equipment used are described and a new “wireless” method for measuring coupling impedances between distant nodes is presented. The most important results of the measurements are also summarized.
Design aspects of hybrid compensation systems
Authors: Mattavelli P. , Tenti P. 
Published: July 2010

AbstractThe paper focuses on theoretical design considerations of hybrid compensation systems, which include tuned L‐C filters, thyristor‐controlled reactors (TCR) and thyristor‐switched capacitors (TSC). The approach derives from optimum compensation technique employing parallel configuration of reactors and capacitors, where purely capacitive compensation is substituted by L‐C branches. This solution, recommended for distorted systems, allows a decomposition of the load currents in terms which are not strongly dependent of the source impedance. The method is also applied to the design of multiple tuned L‐C filters, taking into account load current harmonics and the effect of the supply impedance.
Methods of condition monitoring and fault diagnosis for induction motors
Authors: Thorsen O. V. , Dalva M. 
Published: July 2010

AbstractThe study gives a synopsis over condition monitoring methods both as a diagnostic tool and as a technique for failure identification in high‐voltage induction motors. Methods of fault detection are reviewed and analyzed: mechanical (vibrations, shock pulses, acoustic, speed fluctuations), electro‐mechanical (currents, surges, partial discharges, leakage fluxes) and temperature‐, oil particle‐, gas analysis, and performance‐ and visual methods. The study indicates how different types of faults generate different frequency components in vibration spectra, in motor supply current, in torque and in magnetic field, and relationships between fault types and spectra have been developed. Supply current waveform analysis has been applied to demonstrate the detection of broken rotor bars and bearing faults.
Resonant DC‐AC converter with low ripple output voltage
Authors: Alexa D. , Ionescu F. , Neacsu D. O. , Radomirescu B. 
Published: July 2010

AbstractThe paper introduces a new resonant DC link inverter that allows PWM capability and lower overvoltages on the load voltage. This is provided by keeping the clamping capacitor at a constant voltage, while the resonant circuit is continuously operated. Both DC link and inverter output present pulses with low magnitude. The new resonant circuit has the following main advantages: a more precise control of the pulse widths of the load voltage and the resonant circuits elements are less stressed since the current load of these elements is smaller. The design hints are also given.
Experimental investigation of grounding grid impulse characteristics
Authors: Stojković Z. , Savić M. S. , Nahman J. M. , Salamon D. , Bukorović B. 
Published: July 2010

AbstractThe paper provides a procedure for experimental determination of the grounding grid impulse characteristics. The principles of forming the measuring scheme, disposition and characteristics of the equipment used are described. Some of the numerous experimental results for the square‐shaped grounding grid are presented. The results have been obtained for various shapes, magnitudes and discharge points of the impulse currents and are related to the cases without soil ionization around the grid elements.
Cost‐benefit evaluation of voltage conditioners installation in industrial and commercial power systems
Authors: Quaia S. , Tosato F. 
Published: July 2010

AbstractIn industrial and commercial sectors, loads are becoming increasingly sensitive to brief supply voltage disturbances. As a consequence, today voltage dips have more impact than just a few years ago. Fast voltage conditioners, improving the load immunity characteristics and accordingly reducing the expected number of load interruptions or malfunctions due to supply voltage dips, can allow large cost savings. Different categories of voltage conditioners are existing today, ranging from energy‐stored devices (like uninterruptible power supply) to no energy‐stored devices (like static voltage booster). To reduce the effects of supply voltage dips on a given plant, usually several different possible arrangements must be investigated, depending on the conditioners type, size and bus location. To determine the optimal arrangement is not always immediate. A methodology based on the minimum revenue requirement (MRR) is proposed in the paper, and a numerical example is given as well.
Effect of earth stratification on impedances of power transmission lines
Authors: Moghram I. S. 
Published: July 2010

AbstractAccurate prediction of ground fault currents in above ground transmission systems requires that the earth be modelled using accurate representation. Traditionally, the earth is modelled as a homogeneous half space of unit permeability. In practice, the earth is composed of strata of various resistivities and permeabilities. Equations developed for multi‐layered earth model using the double integral transform techniques are presented in this paper. Results for two‐ and three‐layered earth demonstrate that the zero‐sequence resistance and the zero‐sequence reactance are considerably affected by characteristics of earth stratification. The presented equations can be used to aid electrical engineers in predicting AC fault currents more accurately.
On the realizability of balanced untransposed overhead line configurations
Authors: Faria J. A. Brandāo 
Published: July 2010

AbstractA procedure for synthesizing balanced untransposed overhead three‐phase line configurations has been recently presented. However, such a procedure is based on the simplifying assumption that the soil influence can be described by an impedance matrix with all elements equal. In the present paper we abandon that assumption and model the earth effect via the Dubanton 's approach. In the frame of this more accurate model we show that the realizability of such untransposed balanced line configurations cannot indeed be assured, not even in the low‐frequency and high‐frequency limiting cases.
DSP‐based implementation of an improved control algorithm of a three‐phase active filter for compensation of unbalanced non‐linear loads
Authors: Singh B. , Singh B. N. , Chandra A. , Al‐Haddad K. 
Published: July 2010

AbstractThis paper deals with an implementation of a new control algorithm/or a three‐phase active filter (AF) to eliminate harmonics, compensate reactive power and to balance unbalanced non‐linear loads. An insulated‐gate‐bipolar transistor (IGBT)‐based current‐controlled pulse‐width modulated (PWM) voltage‐source inverter (VSI) with a DC‐bus capacitor is used as an AF. The reference supply currents are derived in phase with supply voltages using a sliding mode controller (SMC) over DC‐bus voltage of the AF.A digital signal processor (DSP) is used to implement the control algorithm of the AF. An indirect PWM current control over the reference and sensed supply currents is implemented for generating the gate signals for IGBT of the AF. Test results of the proposed AF are given to demonstrate the harmonic elimination, reactive power compensation and load‐balancing capabilities of the AF.
Steady‐state power flow and voltage control by unified power‐flow controllers, part 1: Modelling and algorithms
Authors: Song Y. H. , Liu J. Y. 
Published: July 2010

AbstractThe unified power‐flow controller (UPFC), with its unique combination of fast shunt and series compensation, offers a versatile device for the relief of transmission constraints. However, in order to realise this potential benefit, appropriate local and global power‐system control strategies must first be developed. UPFC steady‐state model and its implementation in normal (open‐loop) power flow has been investigated by a number of investigators. This paper further develops the power‐injection method based on optimal multiplier power flow for the steady‐state control of UPFC for power‐flow control and voltage support. The proposed power injection power‐flow control can be effectively used to derive UPFC control parameters to achieve the required control objectives.
Steady‐state power flow and voltage control by unified power‐flow controllers, part 2: Applications
Authors: Song Y. H. , Liu J. Y. 
Published: July 2010

AbstractThe unifiedpower‐flowcontroller(UPFC) isa powerfuldeviceforthe reliejroj'transmission constraints. Part 1 of the paper proposes novel steady‐state modelling and control algorithms for the study of UPFC, which use power‐injection models to derive control parameters for UPFC to achieve the required line active power control and bus‐voltage support. The proposed method does not change the symmetrical structures of Jacobian matrix, avoids the initialisations of control parameters and can cover a wide control range of UPFC due to the characteristics of optimal multiplier power‐flow algorithms employed. This paper describes in detail the applications of the proposed theory in a 28‐node system. The convergence of controlled power flow is analysed. Control performance has been evaluated. The numerical results presented clearly illustrate the effectiveness of the proposed approach.
Correction of resistance measurement of large grounding systems
Authors: Berberović S. , Boras V. 
Published: July 2010

AbstractA method for the systematic error correction which appears at the grounding system resistance measurement by means of an auxiliary current electrode, when the distance between the edge of the grounding system and the center of the current electrode is shorter than the minimum distance required by the standard, is presented in this paper. The systematic error increases with the ratio of the size of the grounding system to its distance from the current electrode. The method for the correction of the systematic error is based on modelling of grounding system and current electrode by hemispheres in uniform and two‐layer soil model. The calculation results are presented by diagrams, which are useful for the evaluation of systematic error.