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International Review of Electrical Engineering - August 2008 - Papers

Decision Circuit and Bit Error Rate Estimation for Absolute Polar Duty Cycle Division Multiplexing
Parametric Analysis of the Theoretical Wenner Resistivity Profiles Across a Buried Perfectly Conducting Sphere
Optimum Vias Distribution for a Printed Circuit Board Using 3D Modelling and Simulation
Applying Current Injection to Transient Upload Response of FPGA-Based Boost Converter
A Novel Control Strategy for Active Power Filter Using Synchronous Reference Frame (SRF) ADALINEs
Wind Energy Conversion Systems Fault Diagnosis Using Wavelet Analysis
Power System Transient Stability Assessment Using On-line Measurement Data
Finite Element Modeling and Analysis of Underground High Voltage Cables Using Magnetic-Total Current Density and Thermal Coupled Models
Evaluation of Over/Under Voltage Relay at Non-sinusoidal Conditions
Protection of Dispersed Generation Connected to a Transmission Network
Emission and Economic Load & Reserve ‎Dispatch with Frequency Constraints in ‎Competitive Power Market
Power Flow and Loss Tracing in Deregulated Transmission System Using Proportional Tree Method
Correlation and Regression of Wholesale Electricity Market Daily Prices in Europe
An IRFO System with Stator and Rotor Resistance Identification for the Induction Motor
Full-digital Implementation of ISFOC for Single-Phase Induction Motor Drive Using dSpace DS 1104 Control Board
Implementation of a Sensorless Speed Control of Induction Motor Using RFOC Strategy
Analytical Investigation of Slotted Air-gap Surface Mounted PMSM with Magnet Bars Magnetized in Shifting Direction
Multidisciplinary Design Optimization Applied to an Electric Drive Train

International Review of Electrical Engineering - Papers

Decision Circuit and Bit Error Rate Estimation for Absolute Polar Duty Cycle Division Multiplexing

by A. Malekmohammadi, M. K. Abdullah, G. A. Mahdiraji, A. F. Abas, M. Mokhtar, M. F. A. Rasid, S. M. Basir

Vol. 3. n. 4, pp. 592-599

Abstract - A novel concepts of decision circuit and Bit-error-rate (BER) estimation method for Absolute Polar Duty Cycle Division Multiplexing (AP-DCDM) is proposed. The concepts have significant differences to those used in conventional microwave communication receivers. This is due to the unique characteristics of the multilevel signal produced in AP-DCDM system. The BER estimation method is validated by simulation and compared against bit-to-bit comparison method.

Keywords: Electrical multiplexing, demultiplexing, decision circuit, Bit Error Rate estimation.

Parametric Analysis of the Theoretical Wenner Resistivity Profiles Across a Buried Perfectly Conducting Sphere
by V. Boras, T. Baric, A. Muharemovic

Vol. 3. n. 4, pp. 600-612

Abstract - This paper considers method for parametric analysis of the theoretical apparent soil resistivity profiles over spherical ore deposit, or metallic object in the form of sphere buried in a uniform or a two-layer soil using the Wenner four-point method. The apparent soil resistivity is calculated by means of complex image method using optical analogy and analogy with electrostatic fields. Comprehensive equations for calculating apparent soil resistivity using the Wenner method across perfectly conducting sphere are readily available. Several synoptic image location maps are introduced to explain this method of images as it is applied to the calculation of the apparent soil resistivity. The main application of proposed model is the estimation of the influence of spherical buried metallic objects when using the Wenner method.

Keywords: Apparent Soil Resistivity, Method of Images, Perfectly Conducting Sphere, Two-Layer Soil, Uniform Soil, Wenner Method.

Optimum Vias Distribution for a Printed Circuit Board Using 3D Modelling and Simulation
by A. Pleşca, A. Baraboi, M. Adam, C. Pancu

Vol. 3. n. 4, pp. 613-620

Abstract - Nowadays because of impressive development of power electronic components and integrated circuits there is a high density of active electronic components on printed circuit boards (PCB). This also had involved new aspects as regard the thermal power management at the contact between power semiconductor case and printed circuit board. So, a multi-layers PCB and vias solution have been adopted to improve the thermal exchange between power components and environment. At a given density of active electronic components it’s important to achieve an optimum vias distribution on the PCB. 3D thermal simulations have been used in order to analyze the vias distribution and its geometry on the base of thermal resistance principle.

Keywords: printed circuit board, vias distribution, thermal analysis.

Applying Current Injection to Transient Upload Response of FPGA-Based Boost Converter
by K. I. Hwu

Vol. 3. n. 4, pp. 621-628

Abstract - In this paper, an input inductor current injection technique, together with the one-comparator counter-based pulse-width-modulation (PWM) control strategy, is presented herein and applied to the boost converter to upgrade its stability and transient upload response. This is easy to realize based on the field programmable gate arrays (FPGA). The detailed illustration of the proposed control strategy is provided, along with some experimental results.

Keywords: Current Injection, One-Comparator, Counter-Based, PWM, FPGA.

A Novel Control Strategy for Active Power Filter Using Synchronous Reference Frame (SRF) ADALINEs
by Y. Han, M. M. Khan, L. Xu, L. Zhou, G. Yao, C. Chen

Vol. 3. n. 4, pp. 629-645

Abstract - Conventionally, the majority of existing active power filter (APF) control strategies in literature adopts feed-forward control scheme, which results in switching notches (sharp-rising or falling ripples) in the source-side currents at conduction instants of diode/thyristor rectifier load. This paper proposes an effective control scheme for 3-phase 3-wire APF using neural algorithmic approach. The proposed method utilizes feedback control plus feed-forward control structures to achieve a smooth filtering performance. The feedback loop minimizes the steady-state error by using two separate proportional integral (PI) regulators in d-axis and q-axis synchronized with grid voltages, respectively. The feed-forward loop serves the purpose of load disturbance rejection and it significantly enhances performance of APF by using adaptive linear neural networks (ADALINEs). Three possible application of ADALINE in different reference frames, namely, stationary a-b-c frame, stationary α-β frame and synchronous d-q frame, are compared through digital simulation using Matlab/Simulink. The synchronous frame ADALINE is found to have overwhelming advantages over the stationary frame solutions in terms of simplicity, robustness and easy of implementation using digital signal processor (DSP). The effectiveness of the proposed control scheme has been confirmed by extensive simulation and experimental results.

Keywords: ADALINE; harmonic distortion; PWM control; power quality; active power filter.

Wind Energy Conversion Systems Fault Diagnosis Using Wavelet Analysis
by E. Al-Ahmar, M. E. H. Benbouzid, S. Turri

Vol. 3. n. 4, pp. 646-652

Abstract - This paper deals with the investigation of a specific transient technique suitable for electrical and mechanical failure diagnosis in an induction generator based wind turbine. The investigated technique is a combination of the Discrete Wavelet transform, statistics and the energy. Experimental investigations carried out on a 1.1 kW induction generator based test bench show that the proposed technique can unambiguously diagnose failures under transient conditions.

Keywords: Wind turbine, induction generator, Discrete Wavelet Transform (DWT), failure diagnosis.

Power System Transient Stability Assessment Using On-line Measurement Data
by A. Shamisa, M. Karrari, O. P. Malik

Vol. 3. n. 4, pp. 653-661

Abstract - With the growing complexity in modern power systems, many utilities increasingly face the threat of transient stability problems. There is a pressing need for the inclusion of on-line dynamic security assessment capabilities in energy management systems. Dynamic security analysis entails evaluation of the ability of the power system to withstand a set of contingencies and to survive transition to acceptable steady-state conditions. To provide accurate results, methods based on Lyapunov functions need accurate models and parameters of the power system that are not usually available. Moreover, the configuration of the power systems changes during operation. For this reason, estimation of stability indices based on online measured data (not model) is gaining momentum. In this paper, nonlinear time series is used to predict transient stability of the system. In the proposed method, first the post-fault state trajectory is predicted with nonlinear time series forecasting algorithm, and then by the controlling unstable equilibrium point concept, and kinetic and potential energies at CUEP and clearing time, the transient stability of the system is assessed.

Keywords: Transient Stability in Power Systems, Online Measurement, Potential Energy Boundary Surface, Nonlinear Time Series Forecasting.

Finite Element Modeling and Analysis of Underground High Voltage Cables Using Magnetic-Total Current Density and Thermal Coupled Models
by M. Rachek, S. NaitLarbi

Vol. 3. n. 4, pp. 662-667

Abstract - This work present a modeling of underground isolated power cables through the coupled magnetic-Eddy current and thermal formulations solved using the finite element method (FEM). The governing magnetic and electric fields equations expressed in term of Magnetic-Vector-Potential (MVP) is strongly coupled with total Current density equation which include Eddy current (EC), source and Displacement Current densities which permit to take into account the skin and proximity effects. The computed (EC) density losses are introduced as heat source in the free transient thermal equation associated with the convection heat transfer. The thermal analysis solved using the iterative time-stepping algorithm and (FEM) lead to the temperature distribution at each step time. A single and multicircuit three-phase underground power cables arrangements are presented as the analysis devices in order to analyse the magnetic flux density and the time-space temperature.

Keywords: Magnetic-eddy current-thermal models, finite element, underground power cables.

Evaluation of Over/Under Voltage Relay at Non-sinusoidal Conditions
by E. İnan, M. Şengül, B. Alboyaci

Vol. 3. n. 4, pp. 668-672

Abstract - The effects of non-sinusoidal voltages on the performance of an over/under voltage relay are experimentally studied. The frequency and amplitude of individual harmonics were adjusted with a programmable power source and the operating times of the relay were examined. To fully appreciate the harmonic problem, first pure sine waveform is examined and then compared with harmonic rich waveforms. The goal of this paper is to maximize the availability of protection by showing the risk of relay mis-operation under distorted voltages.

Keywords: Harmonic, Protection, Under/over Voltage Relay.

Protection of Dispersed Generation Connected to a Transmission Network
by D. Labed, A. Bouzid

Vol. 3. n. 4, pp. 673-681

Abstract - In this paper we present; a distance protection based on the dialogue of two protections using the numerical technology of relay: REL316*4(ABB) and 7SA612(Siemens), to supervise the dispersed generation connected through a HV line. This constitutes a powerful means in term of speed and of selectivity for the elimination of the lines and bars faults; It can also ensure a "distant" help under good conditions. The basic principal of a numerical distance relay is described in this paper. A 220 kV, 51.6 km transmission line and a MHO type distance relay are selected as examples for fault simulation and relay testing. A demonstration tripping and automatic reclosure of relay REL316*4 and 7SA612 will be shown, and the fault currents discussed. Graphs showing the phase voltages and currents will be inspected.

Keywords: Distributed Generation, Numerical Distance Relay, ABB REL316*4, SIPROTEC 7SA612.

Emission and Economic Load & Reserve ‎Dispatch with Frequency Constraints in ‎Competitive Power Market

by R. Hooshmand, A. Haj Mohammadi

Vol. 3. n. 4, pp. 682-690

Abstract - Economic load dispatch is one of the most important problems in power system operation, therefore the aim of this paper is ‎to establish a method to reduce electricity generation costs with a new approach. This method introduces two new ‎constraints called rate of change of frequency (ROCOF) and minimum frequency as the main constraints in economic ‎dispatch in this paper. This approach reduces emission and fuel costs of the power plants as well as transmission line losses. ‎Therefore, this method has also the capability to control frequency in a desirable range. Finally, the proposed method is ‎simulated on a test system. In the simulation, the economic load flow is solved with spinning reserve, transmission ‎lines losses and generation constraints as well as the two new mentioned constraints, i.e. ROCOF and minimum frequency ‎constraints. Simulation results obtained from the proposed and conventional methods, show advantages of the proposed ‎method.

Keywords: Power Market, Economic Power Flow, Frequency Control, Fuel Cost.

Power Flow and Loss Tracing in Deregulated Transmission System Using Proportional Tree Method

by M. H. Sulaiman, M. W. Mustafa, O. Aliman

Vol. 3. n. 4, pp. 691-698

Abstract - Tracing the flow of electricity becomes an important issue in transmission open access. This is due to transmission open access may bring the fairness and transparency to all users. Since the complexity of electrical transmission system, it is not straightforward to map out the contribution of each generator to lines, losses and loads. Thus there are several algorithms proposed to overcome this matter. This paper discusses and emphasizes the method that uses proportional tree method (PTM) to trace the power transfer from individual generators to the transmission system. After power flow solution is obtained, the system is modeled conceptually like a tree, where the power flow tracing is started from particular generator to a particular line or load through the routes that connect between them. It is also possible to pinpoint the losses at each transmission line to which generator. In this paper, 4-bus, IEEE 14-bus and 30-bus test systems are used to show the effectiveness of the method. Comparison with other method is also given.

Keywords: Power Flow, Proportional Sharing Principle, Proportional Tree Method.

Correlation and Regression of Wholesale Electricity Market Daily Prices in Europe
by G. Majstrovic, D. Bajs, E. Sutlovic

Vol. 3. n. 4, pp. 699-708

Abstract - Comparing to classical goods and services electricity is very specific due to inability to be stored, continuous balance between production and consumption, long time needed for system component construction, frequency and voltage limits, power system dynamics etc. Consequently, due to technological specifics electricity market design is basically similar among the countries, but interconnection capacities between power systems (markets) in Europe and non-harmonized legislative frameworks are limiting power exchanges and market integration. The paper objective is to analyze stochastic characteristics of electricity markets in Europe and to calculate the degree of correlation and regression between mean daily electricity prices (base load day ahead prices) on thirteen power marketplaces in Europe. Price values were collected since the market opening till December 31, 2006 which gives total of 32460 price samples. Price volatility ranges and distributions are also given. The analysis showed strong market correlation within two European market zones: Scandinavian and continental (Germany, Holland, France, Austria and Spain), while other two analyzed markets (Italian and Polish) are poorly correlated to all other markets. Electricity price correlations between these two market zones are relatively low, which means that so far Internal Electricity Market in Europe streams to two sub-markets and some residuals.

Keywords: power exchanges, Europe, wholesale prices, correlation, regression.

An IRFO System with Stator and Rotor Resistance Identification for the Induction Motor
by D. Vukadinović, M. Bašić, L. Kulišić

Vol. 3. n. 4, pp. 709-720

Abstract - This paper presents a new online identification method for the stator and rotor resistance of an induction motor operating in an indirect rotor field oriented (IRFO) control system. The rotor resistance is identified using the MRAS (model reference adaptive system) principle due to the estimated magnitude of the rotor flux. The rotor flux magnitude is estimated in the stationary reference frame (α,β) using the voltage model and the current model. The error signal of the rotor flux magnitude obtained from the two models provides the identification of the rotor resistance. In order to estimate the rotor flux from the voltage model, a new method for elimination of the DC drift based on the observer theory is presented and compared with two very commonly used methods. The stator resistance is identified through two methods. The first method is based on the MRAS procedure. The second method is derived in the d,q reference frame aligned to the stator current vector. This paper investigates the possibility that the stator resistance, identified by either the first or second method, could be used as an input parameter for the rotor resistance identification method. The validity of the proposed approach is verified by realistic simulation and experimentation.

Keywords: Induction motor, Adaptive control, Rotor field control, Stator and rotor resistance.

Full-digital Implementation of ISFOC for Single-Phase Induction Motor Drive Using dSpace DS 1104 Control Board
by H. Ben Azza, M. Jemli, M. Gossa

Vol. 3. n. 4, pp. 721-729

Abstract - The extensive use of single-phase induction motor has encouraged a lot of researchers to investigate alternatives to employ a single-phase induction motor drive (SPIMD) system with low and high performance ability. This paper investigates Indirect Stator Flux Oriented Control (ISFOC) of SPIMD to employ low-cost systems for low power applications. However, model asymmetry in SPIMs causes extra coupling between two stator windings and resulting in an unbalanced machine operation. To use the field orientation control, the asymmetry must be eliminated by using an appropriate variable changing. The performance of the newly developed ISFOC has been verified by simulation and then experimentally on a 1.1 kw squirrel-cage single phase induction motor drive. The algorithm is programmed with Matlab/Simulink and downloaded in the dSpace DS 1104 control board. The performance of the drive was found to be excellent in both simulation and experiment.

Keywords: Single Phase Induction Motor (SPIM), Indirect Stator Flux Oriented Control (ISFOC).

Implementation of a Sensorless Speed Control of Induction Motor Using RFOC Strategy
by A. Abbou, H. Mahmoudi

Vol. 3. n. 4, pp. 730-737

Abstract - This paper presents design and implementation a sensorless Rotor Field Oriented Control (RFOC) strategy for induction motor. Model reference adaptive system (MRAS) method is used to estimate the induction motor rotor speed. Experimental results for a 3kW induction motor are presented and analyzed using a dSPACE system with DS1104 controller board based on digital processor Texas Instruments TMS320F240 DSP. The regulator of speed control used is a P-PI type, whose parameters are tuned analytically and practically adjusted. Obtained results demonstrated that the proposed sensorless control scheme is able to obtain high performances.

Keywords: Speed sensorless, MRAS, P-PI controller, RFOC, Induction Motor.

Analytical Investigation of Slotted Air-gap Surface Mounted PMSM with Magnet Bars Magnetized in Shifting Direction
by K. Boughrara, B. Ladghem Chikouche, R. Ibtiouen, D. Zarko, O. Touhami

Vol. 3. n. 4, pp. 738-748

Abstract - An analytical model is presented, which uses two-dimensional field theory in polar coordinates to determine the flux density distribution, cogging torque, back EMF and electromagnetic torque in the slotted air gap of permanent magnet motors with surface mounted magnet bars which are magnetized in shifting direction. The effect of stator slots is introduced by modulating the magnetic field distribution in the slotless stator by the complex relative air gap permeance. The accuracy of the developed model is verified by comparing its results with those obtained from experimental measurement and previously validated numerical finite element code.

Keywords: Magnetic field, conformal mapping, air-gap permeance, permanent magnet synchronous motor, finite element.

Multidisciplinary Design Optimization Applied to an Electric Drive Train
by V. Mester, F. Gillon, S. Brisset, P. Brochet, M. M. Radulescu

Vol. 3. n. 4, pp. 749-758

Abstract - The paper points out a rational methodology to design electric drive trains components taking into account the whole system via a global approach. The aim of this global approach is to assure an optimal global solution. Thus, all components are simultaneously and conjointly designed to obtain the best adaptation to the desired system specifications. This methodology, based on a Multidisciplinary Design Optimization, is used to design the wheel traction motor of an electric kart drive train, designed for a specific application.

Keywords: Global Optimal Design, Traction Motor, Wheel Motor, Systemic Approach, Electric Drive Train.