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Showing papers in "Electric Power Components and Systems in 2003"


Journal ArticleDOI
TL;DR: In this article, a 3-phase shunt active power filter is proposed to compensate harmonics and the reactive power requirement of nonlinear loads, based on sensing line currents only.
Abstract: This paper presents complete design, simulation, and experimental investigations on a 3-phase shunt active power filter to compensate harmonics and the reactive power requirement of nonlinear loads. The paper describes the complete design aspects of power circuit elements and control circuit parameters. The compensation process is based on sensing line currents only, an approach different from conventional methods that require the harmonics and reactive volt-ampere requirement of the load. Various simulation results are presented to study the performance during steady-state and transient conditions to validate the design. A laboratory prototype has been developed to verify the simulation results. The control scheme is realized on a dedicated micro-controller-based system. PWM pattern generation is based on carrierless hysteresis-based current control to obtain the switching signals. Based on simulation and experimental results it can be concluded that the compensation process is simple and easy to impleme...

122 citations


Journal ArticleDOI
TL;DR: The brushless doubly fed reluctance machine (BDFRM) is the least known of a group of electrical machines that include the classic cascaded induction machine, the brushless double-fed slip ring induction machine (DFSRIM), and the BDFIM as discussed by the authors.
Abstract: The brushless doubly fed reluctance machine (BDFRM) is the least known of a group of electrical machines that include the classic cascaded induction machine, the brushless doubly-fed induction machine (BDFIM), and the double-fed slip ring induction machine (DFSRIM). Since its initial development some 30 years ago, the BDFRM has been largely ignored because of the performance limitations imposed by the reluctance rotor design. However, improvements in reluctance rotors, a by-product of the development of the synchronous reluctance machine, have resulted in renewed interest in the BDFRM. This together with the promise of higher efficiency and simpler control compared to the BDFIM means that further investigation of the BDFRM is warranted. This paper is designed to be a starting point for research into the BDFRM. It develops the fundamental modelling equations that are required to carry out research into its dynamics and control. The approach is partly tutorial in nature as it presents some “well-known” anal...

122 citations


Journal ArticleDOI
TL;DR: In this paper, a new voltage stability index is proposed to identify the nodes that are on the verge of voltage collapse, which is calculated at each node of the network using a modified load flow method.
Abstract: The paper presents voltage stability analysis of radial distribution networks. A new stability index is proposed to identify the nodes that are on the verge of voltage collapse. The value of the proposed voltage stability index is calculated at each node of the network. A modified load flow method is used for voltage stability analysis. The modified load flow method incorporates composite load modeling and variations in load pattern at each node. The results are compared with the other known methods of voltage sensitivity indices and found satisfactory. A comprehensive comparison with the recently proposed voltage stability index by Chakravorty and Das [1] is presented in this paper. A detailed analysis of effects of different load models on voltage computation and voltage stability are carried out, and it is observed that for voltage stability analysis, a constant impedance load model can be used without losing the sensitivity of load modeling.

103 citations


Journal ArticleDOI
TL;DR: A simple and efficient algorithm is presented to solve radial distribution networks (RDN), which solves the simple algebraic recursive expression of voltage magnitude and all the data are stored in vector form.
Abstract: A simple and efficient algorithm is presented to solve radial distribution networks (RDN) It solves the simple algebraic recursive expression of voltage magnitude and all the data are stored in vector form The algorithm uses the basic principle of circuit theory and can be easily understood The proposed algorithm has been tested with several distribution networks and results are compared with two other existing methods The effectiveness of the proposed algorithm is demonstrated through two examples

91 citations


Journal ArticleDOI
TL;DR: In this article, an advanced simulation model for brushless dc motor drives using Matlab is presented, where the dynamic characteristics of speed and torque as well as voltages and currents of pwm inverter components can be effectively monitored and analyzed.
Abstract: An advanced simulation model for brushless dc (BLDC) motor drives using Matlab is presented. In the developed model, the dynamic characteristics of speed and torque as well as voltages and currents of pwm inverter components can be effectively monitored and analyzed. Therefore, it can be expected that the developed simulation model can be an easy-to-design tool for the development of BLDC motor drives including control algorithms and topological variations with reduced computation time and memory size.

87 citations


Journal ArticleDOI
TL;DR: In this paper, the optimal gain settings of different types of controllers are obtained using the GA for a two area hydro power system using a brief sketch of the GA and its strategy as a method of control system design is discussed.
Abstract: In this article, load frequency control (LFC) of a two area hydro system is studied. Optimum gain settings of different types of controllers are obtained using the genetic algorithm (GA) for a two area hydro power system. A brief sketch of the genetic algorithm (GA) is presented and its strategy as a method of control system design is discussed. Results are presented for different types of controllers. Analysis reveals that PID controllers give better dynamic responses for a two area hydro system.

76 citations


Journal ArticleDOI
TL;DR: In this paper, the dynamic performance of a two-area interconnected power system consisting of hydropower plants is discussed, where the authors tried to establish that using an HVDC transmission system in parallel with an EHVDc transmission line as an interconnection between two areas has a favorable effect on system dynamic performance in the wake of a small load disturbance in the system.
Abstract: The present research article is devoted to discussing the dynamic performance of a two-area interconnected power system consisting of hydropower plants. It tries to establish that using an HVDC transmission system in parallel with an EHVDC transmission line as an interconnection between two areas has a favorable effect on system dynamic performance in the wake of a small load disturbance in the system. At the outset of the article, the current status of the Indian Power System is summarized, and the challenges ahead for power engineers are discussed in length. The future prospects of hydropower due to environmental considerations, merits of using HVDC transmission systems, and the upcoming interconnected structure of power systems with parallel EHVDC/HVDC transmission systems is presented. The system dynamic performance has been studied with the implementation of optimal AGC regulators in the wake of load disturbance in one of the areas. The investigations carried out justify the application of an HVDC tr...

44 citations


Journal ArticleDOI
TL;DR: In this paper, the performance of a neural network (NN) for automatic generation control of a power system including the Superconducting Magnetic Energy Storage (SMES) unit is investigated. And the results indicate that better control performance can be obtained by the NN controller.
Abstract: This work investigates the performance of a neural network (NN) for automatic generation control of a power system including the Superconducting Magnetic Energy Storage (SMES) unit. First, a single-area power system is represented by the state space model. The reheat effect nonlinearity of the steam turbine is also considered in this model. The control of this system is investigated using a conventional PI controller versus an NN controller. Further computer simulations are performed on interconnected power system with two areas including SMES units. The single-area and two-area systems simulation results both indicate better control performance can be obtained by the NN controller. Only one NN controller, using the back propagation-through-time algorithm, controls the inputs of each area in the power system.

33 citations


Journal ArticleDOI
TL;DR: The iterative process takes four to five iterations to reach the final value with a difference of zero between the successive values of the generated frequency, which is sufficient to predict the behavior of a self-excited induction generator for a given set of operating constraints.
Abstract: This paper presents a new iterative method to analyze the operation of a self-excited induction generator operating under steady-state operating conditions. The iterative method proposed makes it very simple to compute the generated frequency. The iterative process takes four to five iterations to reach the final value with a difference of zero between the successive values of the generated frequency. The model is sufficient to predict the behavior of a self-excited induction generator for a given set of operating constraints. The theoretical results obtained have been verified experimentally for different machines operating under different operating conditions.

28 citations


Journal ArticleDOI
TL;DR: In this paper, a reliability model of accelerated aging processes applied to motor bearing degradation is presented, where bearing damage is created through several accelerated aging process for 5 HP induction motors, and motor vibration signals are examined by statistical and spectral analysis techniques.
Abstract: In this study a reliability model of accelerated aging processes applied to motor bearings is presented. For this purpose, bearing damage is created through several accelerated aging processes for 5 HP induction motors, and motor vibration signals are examined by statistical and spectral analysis techniques. In this sense standard deviation values of the considered signals are determined as the most effective statistical parameter in reflecting the bearing degradation behavior. A new definition, which indicates the reliability level of the bearing, is given as a correlation degree defined between the initial case and any aged case. This relationship is used to establish the reliability model of motor bearing degradation through the exponential variation of the standard deviation for the overall process.

26 citations


Journal ArticleDOI
TL;DR: In this article, a variety of viewpoints from engineers within the power cable industry are presented as to how current trends in the cable industry will influence future cable designs, particularly with polymeric insulation, lapped dielectrics, and improved diagnostic techniques.
Abstract: This paper presents a variety of viewpoints from engineers within the power cable industry as to how current trends in the cable industry will influence future cable designs, particularly with polymeric insulation, lapped dielectrics, and improved diagnostic techniques. The use of high-temperature superconductors and designer polymers as well as the possible availability of conducting polymeric materials is also considered. The paper first reviews how the design of distribution cables has differed historically around the world, the major differences being allied to the systems. Designs largely have been divided into two main categories: those countries following U.K. and European practices, and those having adopted the U.S. system design. However, these differences, such as the use of three-phase cables in the U.K. as opposed to single-phase cables in the U.S., are not so obvious nowadays. Installation practices are becoming rather more standardized, such as the use of ducts, directional drilling, etc. Th...

Journal ArticleDOI
TL;DR: The paper first presents a 3D, one-line-based visualization and then provides several examples of how it could be used to display power system data.
Abstract: Simulation and analysis of power systems often involves modeling extremely complex systems. This is particularly true when the model involves not just the electrical power system, but also other networks layered on top of the power system, such as the accompanying financial transactions. Such layered networks can often involve interactions that are not at all obvious. Interactive visualization can be a very effective means for determining otherwise hidden relationships between various elements in the network. This paper describes the application of interactive 3D for the visualization of electric power system operational and economic data. The paper first presents a 3D, one-line-based visualization and then provides several examples of how it could be used to display power system data.

Journal ArticleDOI
TL;DR: In this article, a nonlinear optimization neural network approach was proposed to study the problem of security-constrained interconnected multi-area economic dispatch, in which tie-line security and transfer constraints in each area were considered.
Abstract: This paper presents a new nonlinear optimization neural network approach to study the problem of security-constrained interconnected multiarea economic dispatch. It is a penalty-minimizing neural network approach with weights based on optimization theory and neural optimization method. In the paper the model of security-constrained multiarea economic dispatch is set up, in which tie-line security and transfer constraints in each area are considered. In addition, a simple analysis of buying and selling contract in a multiarea environment is made. The proposed method is tested on a system of three interconnected areas. The detailed results and analysis are given in the paper.

Journal ArticleDOI
TL;DR: In this article, an active power variation-based protection for HIGFs is developed, and a dissipation factor (DF)-based criterion for identifying load-switching operation is proposed.
Abstract: Many high-impedance ground faults (HIGFs) that happen in low-voltage (LV) systems often cause customer supply loss, fire, and human safety hazards. Traditional ground-fault protection is provided by the residual current circuit breaker (RCCB). The RCCB is usually employed in an analogue measuring circuit and often causes nuisance tripping due to capacitive leakage current and load-switching operations. It offers only ground fault protection to a certain extent and has difficulty in detecting HIGFs associated with a dielectric material defect. In this paper active power variation–based protection for HIGFs is developed, and a dissipation factor (DF)–based criterion for identifying load-switching operation is proposed. They are implemented by cross-correlation analysis between phase voltage and residual current in single-phase networks. A digital protection scheme is also designed. EMTP simulation results show that the new protection can remove the influences of capacitive leakage current and load-switching...

Journal ArticleDOI
TL;DR: In this article, the authors proposed an approach to chaotify a practical induction motor drive system in which field-oriented control is adopted, and the key is to tune the gain of the compensator for the compensation of the increase of rotor resistance due to prolonged operation.
Abstract: This paper proposes an approach to chaotify a practical induction motor drive system in which field-oriented control is adopted. The key is to tune the gain of the compensator for the compensation of the increase of rotor resistance due to prolonged operation. Hence, the occurrence of chaotic motion becomes controllable when the drive system is under a periodic speed command. The validity of the proposed chaotification is verified by both computer simulation and experimental measurement.

Journal ArticleDOI
TL;DR: In this article, an integrated linear and nonlinear control for a unified power flow controller (UPFC) is presented, where three Pulse-Width Modulation (PWM) parameters of the UPFC are controlled by Proportional-Integral-Differential (PID) laws, and an analytic expression of the non-linear control law for the phase angle ϕ2 is obtained by a feedback linearization method.
Abstract: This paper presents an integrated linear and nonlinear control for a unified power flow controller (UPFC). Three Pulse-Width Modulation (PWM) parameters of the UPFC are controlled by Proportional-Integral-Differential (PID) laws, and an analytic expression of the nonlinear control law for the UPFC phase angle ϕ2 is obtained by a feedback linearization method. This combined linear and nonlinear control strategy enables the UPFC to improve power system transient stability and dynamic performance effectively. Simulation results illustrate the effectiveness of the developed control strategy.

Journal ArticleDOI
TL;DR: In this article, the authors presented the details of new schemes for the parameterization step of the continuation power flow method, namely, the total power losses (real and reactive), the power at the slack bus (real or reactive), reactive power at generation buses, and transmission line power losses.
Abstract: The conventional power flow method is considered to be inadequate to obtain the maximum loading point because of the singularity of Jacobian matrix. Continuation methods are efficient tools for solving this kind of problem since different parameterization schemes can be used to avoid such ill-conditioning problems. This paper presents the details of new schemes for the parameterization step of the continuation power flow method. The new parameterization options are based on physical parameters, namely, the total power losses (real and reactive), the power at the slack bus (real or reactive), the reactive power at generation buses, and transmission line power losses (real and reactive). The simulation results obtained with the new approach for the IEEE test systems (14, 30, 57, and 118 buses) are presented and discussed in the companion paper. The results show that the characteristics of the conventional method are not only preserved but also improved.

Journal ArticleDOI
TL;DR: In this article, a methodology for incorporating voltage sag ride-though in the design of variable speed AC drives and other sensitive loads with dynamic voltage restorers is presented, and validation is performed by comparing results of the modeling method described in this article with results from the performance tests.
Abstract: Increasing concern is being expressed regarding the issue of power quality. On large interconnected networks, suppliers are vulnerable to system faults (the main cause of disturbances). In this paper, a methodology for incorporating voltage sag ride-though in the design of variable speed AC drives and other sensitive loads with dynamic voltage restorers is presented. This article describes a modeling technique for the open and closed loop control of a dynamic voltage restorer (DVR) for use within distribution systems. Also, validation is performed by comparing results of the modeling method described in this article with results from the performance tests.

Journal ArticleDOI
TL;DR: Minimal RBFNN (MRBFNN) is a newer version of neural network that provides a minimum number of neurons using the sequential learning and pruning strategy, and fuzzy neural network (FNN) yields fewer fuzzy rules.
Abstract: Radial basis function neural networks (RBFNN) and fuzzy neural networks (FNN) are finding increasing attention as AI techniques. Power systems protection is a complex task in which AI techniques are successfully employed. Minimal RBFNN (MRBFNN) is a newer version of neural network that provides a minimum number of neurons using the sequential learning and pruning strategy. On the other hand, the fuzzy neural network, using a pruning strategy, yields fewer fuzzy rules. These new techniques are employed for the protection of a power network having a thyristor-controlled series capacitor (TCSC) which introduces further complexity into the protection problem. A comparison of the two new schemes is also outlined.

Journal ArticleDOI
TL;DR: In this article, the applicability of high-voltage direct current (HVDC) technology and static Volt-Amp Reactive (VAR) compensation to aid damping of low-frequency interarea oscillations in the Mexican interconnected system (MIS) is discussed.
Abstract: This paper discusses the results of preliminary studies conducted to examine the applicability of high-voltage direct current (HVDC) technology and static Volt-Amp Reactive (VAR) compensation to aid damping of low-frequency interarea oscillations in the Mexican interconnected system (MIS). The study of interarea oscillations and the design of controls is done using modal analysis of a linearized AC/DC state space model of the power system at a particular operating point. The utilized methodology is tested on a planning model of the MIS that includes a proposed HVDC transmission system embedded in an AC network in which several SVCs are used for dynamic voltage support. Detailed time-domain analyses are performed to complement knowledge on the effect of FACTS technology on system transient behavior.

Journal ArticleDOI
TL;DR: In this article, the authors presented an algorithm for the parallel solution of the security constrained optimal power flow problem in a decentralized framework, consisting of regions, using a price-based mechanism that models each region as an economic unit.
Abstract: This paper presents an algorithm for the parallel solution of the security constrained optimal power flow (SCOPF) problem in a decentralized framework, consisting of regions, using a price-based mechanism that models each region as an economic unit. We first solve the distributed optimal power flow (OPF) problem to determine the maximum secure simultaneous transfer capability of each tie-line between adjacent regions by taking into account only the security constraints imposed on the tie-lines. In this article, the line outage distribution factors (LODF) calculated at the current state are used to formulate the appended constraints. Once the secure transfer capability of each tie-line is determined, the intraregional SCOPF is performed using the conventional linear programming (LP) approach. A description of the inclusion of security constraints with the distributed optimal power flow algorithm will be given, followed by the case studies for Korea Electric Power System.

Journal ArticleDOI
TL;DR: In this article, the load flow problem is considered as an optimization problem and is decoupled into two subproblems, and the assumptions on voltage magnitudes, angles, and r/x ratios necessary for decoupling the network in the conventional FDPF are eliminated.
Abstract: This paper presents a new, robust, and fast technique to obtain the load flow solution in distribution networks. The proposed method is based on the Newton-Raphson technique using equivalent current-injection and rectangular coordinates. The load flow problem is considered as an optimization problem and is decoupled into two subproblems. The assumptions on voltage magnitudes, angles, and r/x ratios necessary for decoupling the network in the conventional FDPF are eliminated in the proposed method. This method is simple, insensitive to r/x ratios of the distribution lines, and uses a constant Jacobian matrix. It is solved similar to FDPF. Test results of the proposed method on a sample six-node and the IEEE 34-node systems are given to illustrate the superior performance. These results indicate that the proposed method is efficient and accurate and has great potential for online applications.

Journal ArticleDOI
TL;DR: In this article, a comprehensive coverage of the first part of a transverse flux machine design procedure is given, taking into account the already reported results and the existing experience, resulting in a fully designed TF machine.
Abstract: The transverse flux (TF) machine has an excellent torque-to-volume ratio in comparison to conventional machines. For this reason, the TF machine is well suited for direct drive systems. The electromagnetic design procedure of a TF machine consists of two main parts. In the first part of this article the main dimensions, parameters, and performance are estimated. In the second part, the magnetic circuit is optimized and the steady-state characteristics are computed by using a three-dimensional finite element method (3D-FEM) analysis. In this article, a comprehensive coverage of the first part of a TF machine design procedure is given, taking into account the already reported results and the existing experience. The sizing equation is obtained and the estimation procedure is applied in an example, resulting in a fully designed TF machine. The present work can serve as a guideline for a TF machine designer who wants to have a first machine estimation.

Journal ArticleDOI
TL;DR: In this paper, a steady-state analysis of a single-phase, self-excited reluctance generator based on a qd model and harmonic balance technique is proposed, where a necessary constraint function is derived to reveal the parametric dependency of the system which has a combination of selfexcitation and nonlinear characteristics.
Abstract: A method of steady-state analysis of a single-phase, self-excited reluctance generator based on a qd model and harmonic balance technique is proposed. A necessary constraint function is derived to reveal the parametric dependency of the system which has a combination of self-excitation and nonlinear characteristics. Moreover, the proposed method can be used to reconstruct the machine waveforms, which can provide a better understanding of the system. The comparison between experiment and simulation shows a good agreement. This method not only offers guidance for the design of a single-phase, self-excited reluctance generator, but also provides a general methodology for other self-excited generator steady-state analysis under unbalanced terminal conditions.

Journal ArticleDOI
TL;DR: In this paper, a differential global positioning satellite (DGPS) system-based instrument for the measurement of overhead transmission conductor sag is proposed for overhead transmission overhead transmission, where the main advantage of the concept is the real-time direct measurement of a parameter (i.e., conductor sag) needed for the operation of the transmission system without intermediate measurement of conductor tension, temperature, and ambient weather conditions.
Abstract: This article deals with overhead transmission conductor sag. The design, construction, instrumentation, and testing of a differential global positioning satellite (DGPS) system-based instrument for the measurement of conductor sag is proposed. Inherent and intentional errors in GPS technologies are discussed, and the DGPS method is described for accuracy enhancement. A DGPS-based overhead conductor-sag measuring instrument has been designed, constructed, and subjected to selected laboratory bench and power substation testing. A method to measure directly the physical sag of overhead conductors is described. The main advantage of the concept is the real-time direct measurement of a parameter (i.e., conductor sag) needed for the operation of the transmission system without intermediate measurement of conductor tension, temperature, and ambient weather conditions.

Journal ArticleDOI
TL;DR: This paper presents the methodology used in the development of an object-oriented optimal power flow program and showed that the proposed program is as fast as the one based on a conventional programming language.
Abstract: This paper presents the methodology used in the development of an object-oriented optimal power flow program. The optimal power flow problem is modeled as a class inherited from a load flow class and has direct access to a main power system object class. Each power system component, such as generators, transformers, transmission lines, loads, and capacitor banks, is modeled as an object and pro-structured in the same way as in a real electrical network. The OPF problem is formulated using a quasi-Newton method iterated with the Newton-Raphson load flow module. A special matrix class is used to handle all the system matrices where input and output data can communicate with the OPF computing modules via an object-oriented graphical user interface and through an object-oriented database. The tests carried out on the IEEE 30-bus and the IEEE 118-bus systems showed that the proposed program is as fast as the one based on a conventional programming language.

Journal ArticleDOI
TL;DR: In this paper, a dual-inverter pole-changing induction motor drive was used to model the DC-link current of electric vehicles and suppress its harmonic contamination by employing the double Fourier series.
Abstract: In electric vehicles, the DC-link current harmonics of the motor drive can seriously affect the battery management device and even the battery life. The purpose of this paper is to analyze the DC-link current of a newly developed dual-inverter pole-changing induction motor drive, and hence to suppress its harmonic contamination. The key is to employ newly the double Fourier series to model the harmonic current in the DC link of the dual inverter, which adopts a special arrangement of space-vector pulse-width modulation. Digital-signal processor-based implementation and experimentation are given to verify the theoretical analysis.

Journal ArticleDOI
TL;DR: In this paper, an advanced static VAR compensators (ASVCs) are used to improve the transient stability of electric power systems, which has superior performances compared to the conventional control techniques for these systems.
Abstract: Advanced static VAR compensators (ASVCs) are used to improve the transient stability of electric power systems. In this paper we present a new control strategy, which has superior performances compared to the conventional control techniques for these systems. The proposed method utilizes a novel current reference based on the transient energy function (TEF) approach. It also includes the voltage limits in the optimizing process using the Lyapunov theory and linear programming. In addition, it is optimized considering the permissible system conditions. A continuous control of the reactive power flow is also achieved. The proposed ASVC is modeled in single-machine and multimachine systems. In order to verify the excellent performances of the proposed approach compared to the conventional control techniques and systems without ASVC, simulation results in response to severe disturbances in a single-machine system as well as a three-machine system are provided.

Journal ArticleDOI
TL;DR: In this paper, a vector-controlled permanent magnet synchronous motor is compared under both Proportional Plus Integral (PI) and Fuzzy logic (FL) speed control.
Abstract: A frequently discussed application of artificial intelligence in motion control is the replacement of a standard Proportional Plus Integral (PI) speed controller with a fuzzy logic (FL) speed controller. A common conclusion that emerges from such studies is that the FL control provides superior performance. However, such a conclusion usually is based on a limited simulation and/or experimental study. It appears that a thorough comparison of the drive behavior under PI and FL speed control, using simulations and an experimental rig, is still missing. This paper attempts to provide such an in-depth comparison of the operation of a vector-controlled permanent magnet synchronous motor. Speed responses under PI and FL speed control are at first simulated and then measured on the experimental rig for a variety of operating conditions. Two different machines are used in simulation and experimentation, enabling a better generalization of the results. The transients studied include response to a large step speed c...

Journal ArticleDOI
TL;DR: In this paper, the authors present a thermal model for top oil temperature calculation in transformers with forced oil and water circulation, which is completely based on the heat transfer theory and is aimed at estimating transformer loading possibilities, but also at maintenance or reconstruction planning purposes.
Abstract: The paper presents the thermal model for top oil temperature calculation in transformers with forced oil and water circulation. The model is completely based on the heat transfer theory. The thermal parameters change in time, due to the sedimentation of substances from the water and the oil to the heat exchanger surfaces. Fouling factors at the water and oil sides can be determined based on measurements. The results of procedure application on the hydro power station block transformer 2 × 190 MVA/380 MVA are given in the paper. The model is aimed at estimation of transformer loading possibilities, but also at maintenance or reconstruction planning purposes.