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Power Delivery, IEEE Transactions on

Issue 2 • Date Apr 1999

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Displaying Results 1 - 25 of 48
  • Application of dominant harmonic active filter system with 12 pulse nonlinear loads

    Page(s): 642 - 647
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (608 KB)  

    Harmonic filtering is required for 12 pulse rectifier-utility interface to meet IEEE 519 harmonic current limits. Passive filter techniques employ tuned L-C filters at dominant 11th and 13th harmonic frequencies. However, they also require 5th and 7th tuned filters to avoid series and parallel resonance conditions. State of the art active filtering solutions require high bandwidth and relatively large rating PWM inverters for harmonic filtering of 12 pulse rectifier loads. Thus existing passive and active harmonic filtering solutions are not cost-effective for high power 12 pulse rectifier loads. Dominant harmonic active filter (DHAF) based on square-wave inverters is proposed to cost-effectively meet IEEE 519 harmonic current limits for 12 pulse rectifier loads. The proposed DHAF system employs square-wave inverters switching at 5th and 7th harmonic frequencies, which are transformer coupled in series with 11th and 13th passive filters respectively. The square-wave inverters are controlled to provide `harmonic isolation' between the supply and load at 5th and 7th harmonic frequencies. The square-wave inverters are rated 1%-2% of the load kVA rating. The proposed DHAF system eliminates the need for large kVAR rated and bulky 5th and 7th passive filters, delivers superior harmonic filtering performance, and provides cost-effective harmonic filtering solution. Simulation results are given to validate the `harmonic isolation' feature at 5th and 7th harmonic frequencies, and also demonstrate harmonic filtering required to meet IEEE 519 harmonic current limits View full abstract»

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  • Selection of passive elements for a three-level inverter based static synchronous compensator

    Page(s): 655 - 661
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    Mathematical models for a three phase three-level static synchronous compensator (STATCOM) working with both fundamental frequency modulation and selective harmonic elimination modulation are described. The mathematical models were obtained by assuming that the power system and the operation of the STATCOM are on a balanced three-phase basis. The mathematical models were simplified to obtain the STATCOM AC side current, the DC capacitor voltage and the ripple for both switching strategies. These simplified design tools were validated using the exact model. The resonance between the DC side capacitance and the coupling reactance was studied using the mathematical model and the resonance frequency for the three-level STATCOM was obtained. The resonance frequency was validated against results of electromagnetic computer simulations. Using the design tools developed and considering the resonance studies, the process for selection of the size of DC side capacitors for a small STATCOM was demonstrated View full abstract»

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  • An assessment of conductor temperature rises of cables, caused by a sudden application of short pulse in a daily cyclic load

    Page(s): 307 - 313
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    The method for calculating cyclic and emergency current power cable ratings has been elaborated for many years and has been standardized in form of IEC standards based on the application of a step function. To achieve a better accuracy, a computer method has been developed, based on finite difference approaches. With the propose procedures, this paper provides a sound basis for the accurate evaluation of temperature rises of conductor in cyclic load calculations. In addition, it proposes a compression-decompression approach for evaluating the temperature rise of the conductor, caused by the application of rectangular current pulses in daily cyclic load View full abstract»

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  • Test systems for harmonics modeling and simulation

    Page(s): 579 - 587
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    This paper presents three harmonic simulation test systems. The purpose is to demonstrate guidelines for the preparation and analysis of harmonic problems through case studies and simulation examples. The systems can also be used as benchmark systems for the development of new harmonic simulation methods and for the evaluation of existing harmonic analysis software View full abstract»

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  • Indices for assessing harmonic distortion from power quality measurements: definitions and benchmark data

    Page(s): 489 - 496
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    For many years, electricity distribution companies have used sustained interruption indices as indicators of the reliability of service provided on their systems. Today, however, many electricity consumers are adversely affected by more subtle voltage disturbances such as harmonic distortion. In response to the increased sensitivity of end-use equipment, many utilities are implementing extensive monitoring systems to assess service quality levels. Such monitoring systems yield massive databases of service quality data. This paper presents indices developed to quantify system service quality with respect to measured harmonic distortion levels. Example benchmark values for the indices are calculated using data from a national distribution power quality data collection project View full abstract»

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  • Modelling of adjustable speed drives for power system harmonic analysis

    Page(s): 595 - 601
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    A three-phase equivalent circuit model is developed to model adjustable speed drives (ASD) for power system harmonic analysis. The validity and accuracy of the model were verified by comparing simulation results with lab test results. Sensitivity studies are then conducted to determine the key factors affecting the harmonic characteristics of ASDs. Guidelines on modelling ASDs for harmonic distortion assessment are developed based on the results View full abstract»

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  • Inductive interference caused to telecommunication cables by nearby AC electric traction lines. Measurements and FEM calculations

    Page(s): 588 - 594
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    The paper investigates the inductive interference caused by AC electric traction lines to nearby buried telecommunication cables. Measurements according to the directives of the International Telecommunication Union (ITU) and calculations using the finite element method (FEM) are presented for a real system. This system consists of an AC electric traction line of the Greek Railways Organization and a buried cable of the Greek Telecommunications Organization. Finally, an analysis concerning the most important operational parameters in determining electric traction line influence is presented. Such parameters are the separation distance between the electric traction line and the buried telecommunication cable, the earth resistivity as well as the number and the material of the mitigation wires View full abstract»

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  • Simulation study of QoS guaranteed ATM transmission for future power system communication

    Page(s): 342 - 348
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    The asynchronous transfer mode (ATM) will support communication services with both constant and variable bit rate, for example, data, voice, video transmissions and, of particular note, multimedia applications combining those service components. However, many problems are required to be solved in order to apply this technique to an electric power company's network. Electric power companies are required to transmit very important information, such as information regarding electric power control. The transmission of this important information is required to have very high quality. Therefore, if the important information and the general information were switched in the same manner, the stringent QoS (quality of service) required for the important information could not be guaranteed. The authors examine the QoS of future utility communications which include ATM-native teleprotection signals, inter-LAN data communications and video conference communications. First, they propose a more accurate model which can be expressed by a multi-state Markovian process for computer data communication traffic. Second, the implementation of a priority control scheme in an ATM switch is proposed to guarantee the QoS of important power system communications. Finally, computer simulations are used to clarify the effectiveness of priority control and the feasibility of future ATM-based utility telecommunication networks View full abstract»

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  • ATM transmissions of microprocessor-based current differential teleprotection signals

    Page(s): 335 - 341
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    This paper describes prudent considerations for applying asynchronous transfer mode (ATM) transmissions, which can provide broadband and multimedia communications as well as flexible, efficient and wide-area networks, to microprocessor-based current differential teleprotection systems. As both functions of current data transmission and simultaneous sampling among remote terminals are required for the telecommunication systems, measures against cell losses and cell delay variations in ATM network elements such as terminal adapters and switches are proposed for the present delay-sensitive teleprotection systems. Allowable system configurations are examined under severe delay constraints in Japan. A new concept of an ATM-native teleprotection system employing time synchronous systems such as GPS is also proposed View full abstract»

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  • A simplified model for zinc oxide surge arresters

    Page(s): 393 - 398
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    A model for metal-oxide surge arresters, derived from that one recommended from the IEEE W.G. 3.4.11, is presented. The main innovation introduced by the paper lies in the simplicity of the criteria proposed for the model's parameter identification. Such criteria allow calculation of the model parameters directly from the standard data reported in the arrester data-sheets with a simple and straightforward procedure. The effectiveness of the model was tested for several arresters of different manufacturer both for medium voltage and for high voltage application. The discharge test results obtained by the manufacturers were compared with the results of simulations performed with the Alternative Transient Program (ATP). Effectiveness and simplicity of use make the proposed model a useful tool for insulation coordination studies involving steep front transients View full abstract»

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  • An improved method of measuring C1 power factor of resistance-graded bushings

    Page(s): 437 - 442
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    This paper discusses C1 power factor of a condenser bushing with resistance graded (RG) porcelain and proposes a method to obtain the intrinsic power factor of the RG bushing View full abstract»

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  • Distribution system compensation using a new binary multilevel voltage source inverter

    Page(s): 459 - 464
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    A new binary multilevel voltage source inverter with separate DC sources is proposed. This n-level voltage source inverter produces a (2 n+1-1)-steps AC voltage output with n full bridge inverters connected in series. The use of selective harmonic elimination modulation technique to either completely eliminate or minimize harmonics is studied. A closed-loop controller to control the capacitor voltages and adjust the inverter reactive power output is developed. Application of such a compensator for dynamic compensation of 13.8 kV distribution system is examined through transient studies using a PSCAD/EMTDC program. The proposed inverter configuration not only reduces the system complexity and its size, but also improves the harmonic profile significantly View full abstract»

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  • Dynamic voltage compensation on distribution feeders using flywheel energy storage

    Page(s): 465 - 471
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    Advancements in power electronics, bearings and materials have made flywheel energy storage systems a viable alternative to electrochemical batteries. A future application of such a device is as an uninterruptible power supply for critical loads on a distribution feeder. However, the same power electronics and flywheel system could also be used for dynamic voltage compensation. A comparison is made between series and parallel connection of such dynamic compensation techniques used to maintain rated load voltage on distribution feeders when there are momentary dips in the supply voltage. For each case a mathematical model is presented and analyzed. The two cases are compared and the series compensation technique is more effective View full abstract»

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  • Differential and common mode propagation in PLC low voltage networks

    Page(s): 327 - 334
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    This paper deals with switching between differential and common mode propagation in power line carriers on low voltage distribution networks. A large field test involving several thousand items of equipment was initiated in 1995, which revealed unexpected results on network environments. An approach to the mode conversion mechanism is explained here. Moreover, experimental measurements confirm the assessment of the amplitude of the phenomena. The common mode propagation in power line carrier (PLC) systems introduces external influences from two directions: telluric currents on one hand; and significant electromagnetic field radiation on the other. Such fields have been both simulated and measured. The consequences of these phenomena are twofold. Firstly, PLC signals from LV networks cross its environment, resulting in the disturbance of others in the neighbourhood. Secondly, it makes electromagnetic compatibility an issue which cannot be neglected View full abstract»

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  • Numerical electromagnetic field analysis on measuring methods of tower surge impedance

    Page(s): 630 - 635
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    The dependence of the tower surge impedance on the measuring methods is studied with the help of NEC-2. The tower surge impedance measured by the direct method varies dependent on the arrangement of the current lead wire. The arrangement of a vertical current lead wire and a horizontal voltage measuring wire gives about 20% higher value than that measured with a horizontal current lead wire in extension to a voltage measuring wire. The former gives about 150 Ω for a typical double-circuit transmission tower and it is almost equal to the value given by the estimating method recommended by the IEEE Working Group. The tower surge impedance evaluated from the current splitting ratio at the tower top is more than 20% higher than that characterized by the direct method when the current is injected into the connecting point from a simulated vertical lightning stroke. On the other hand, the tower surge impedance evaluated by the refraction method is about 10% lower than that characterized by the direct method View full abstract»

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  • Numerical simulation of gas discharge protectors-a review

    Page(s): 405 - 410
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    This paper gives a review of the efforts that have been made to model the gas discharge protector (gas arrester) for use in computer simulations of surge protector co-ordination in low-voltage power systems View full abstract»

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  • Limitations of the ruling span method for overhead line conductors at high operating temperatures

    Page(s): 549 - 560
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    This report summarises the work by the Task Force to review the accuracy of the ruling span method for conductors operated at high temperatures. The basics of the ruling span approximation method have been examined. The traditional ruling span approach can be used with little or no error for a typical overhead line crossing a rolling terrain to predict sags in suspension spans for conductor operating temperatures in the range of 50°C to 70°C. Sensitivity studies were performed using conductors “Lapwing” and “Tern” in order to quantify such ruling span assumptions as the effect of the longitudinal swing of suspension and line post insulators on conductor sags at high temperatures, and the effect of the suspension insulator string length on the equalization of conductor tensions in adjacent spans. Significant errors in estimating the sag at conductor temperature above 100°C may occur if the tension differences are not taken into consideration in line sections consisting of a series of spans of nonequal lengths. It was confirmed that the ruling span method is the most practical way to string conductors in multi-span line sections View full abstract»

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  • Development and calibration of a network-based streaming electrification model for core-form transformer structures

    Page(s): 431 - 436
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    Streaming electrification occurs in large power transformers when oil circulated for cooling purposes acts to separate charges from the Debye layer on the cellulose insulation surfaces. This phenomenon is believed to have caused several catastrophic transformer failures and remains to be satisfactorily understood in realistic geometries. A network-based streaming electrification model is presented which utilizes single winding ducts as the basic element to investigate a core-form structure. The network is first analyzed using hydraulic duct parameters to calculate the oil flow distributions within the structure. This data is then provided to the electrification solver which predicts the charge densities at each duct outlet. The charge density results are ultimately used to determine the streaming potentials at each node based on an a suitable matrix of leakage resistances. Development of the network model is presented along with empirically-based calibration data for a realistic section of core-form transformer geometry View full abstract»

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  • Series compensation on power system with very low harmonic distortion

    Page(s): 512 - 518
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    This paper describes a series compensation scheme employing a capacitor in parallel with two PWM switched reactor modules. The two module PWM switched reactors provide continuously variable reactance by employing simple duty ratio control. The switching instants of the two reactor modules are controlled to have 180° phase shift, but equal duty ratio, to achieve harmonic cancellation. The complete series compensator provides a wide range of capacitive and inductive compensation. The harmonic distortion produced by this series compensation scheme with a single switched reactor and two switched reactors is analyzed and compared. An experimental model of the proposed compensator has been simulated, constructed and tested. In the case of the two module system the voltage harmonics have been found to be well below the IEEE 519-1992 recommended limit with a switching frequency of only 300 Hz. Modulating this new compensator with a swing between minimum capacitive compensation and maximum capacitive compensation at 1 Hz shows its fast dynamic response. The simplicity of the scheme and the quality of the results indicates potential as another useful FACTS controller View full abstract»

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  • Performance of MOV arresters during very close, direct lightning strikes to a power distribution system

    Page(s): 411 - 418
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (608 KB)  

    In 1996, at the International Center for Lightning Research and Testing (ICLRT) at Camp Blanding, Florida, the responses of MOV arresters in an unenergized test distribution system, composed of an overhead line, underground cable, and padmount transformer with a resistive load, were measured during very close, direct lightning strikes to the overhead line. Arresters were installed on the overhead line at two locations 50 m apart (on either side of the strike point) and at the primary of the padmount transformer which was connected to the line via the underground cable. We obtained arrester data for this test configuration from two lightning flashes (containing a total of five strokes) which were artificially initiated from a natural thunderstorm, using the rocket-and-wire technique. We present the simultaneously-recorded arrester discharge current and voltage waveforms from one lightning stroke for one of the two arresters on the line and for the arrester at the transformer primary. Additionally, we estimate the energy absorbed by the arrester on the line as a function of time for the first 4 ms of the lightning event. The records presented are representative of those for all five strokes View full abstract»

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  • Power quality at Champion Paper-the myth and the reality

    Page(s): 636 - 641
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    Reliability and power quality are two of the most discussed topics in the utility industry today. Many groups have performed power quality studies with varying results. One large industrial customer (Champion International) in northern New York State, which experienced numerous process interruptions in its paper mill due to power system disturbances, is the focus of this study. Monitoring methods, results, inadequacies of standards, and unique mitigation techniques used to conquer their problems are discussed in this paper View full abstract»

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  • Unified power flow controller (UPFC): modeling and analysis

    Page(s): 648 - 654
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    The unified power flow controller (UPFC) is a novel power transmission controller. The UPFC provides a full dynamic control of transmission parameters, voltage, line impedance and phase angle. This paper presents a useful tool for power utilities engineers to evaluate the application of the UPFC, its impact on their power system and what would be the shunt and series ratings. This paper gives sets of equations for a system including the UPFC and an equivalent two bus power network. A numerical method tested with Matlab has been successfully validated with an analog model and EMTP. The Matlab code given in the paper allows fast parametric studies to be performed for the application of the UPFC View full abstract»

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  • Small signal analysis of HVDC-HVAC interactions

    Page(s): 525 - 530
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    This paper presents a small signal analysis of interactions between HVAC and HVDC systems. The eigenvalue analysis, along with analysis of participation factors, is firstly described. The eigenvalue sensitivity analysis shows how the changes of AC system parameters influence the stability of the considered HVDC-HVAC system. The influence of short circuit ratio (SCR) changes on both the rectifier and the inverter AC system, is studied by examining the relative movement of the system eigenvalues. The most important conclusions about AC-DC interactions are obtained by investigating the nature of inherent feedback loops between the systems. By examining the changes of all interaction variables, it is determined which of the interaction variables should be controlled and which are better left uncontrolled View full abstract»

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  • Application of high voltage gradient zinc oxide elements to SF6 gas insulated surge arresters for 22 kV-765 kV power systems

    Page(s): 419 - 424
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    Zinc oxide elements have been developed for the surge arrester elements. Basically, these zinc oxide elements are evaluated by the reference voltage VNmA. Newly developed high voltage gradient zinc oxide elements have about twice value VNmA/mm of normal zinc oxide elements. This paper describes the application of the high voltage gradient zinc oxide elements to SF6 gas insulated tank type surge arresters for 22 kV-765 kV power systems View full abstract»

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  • New advances in mitigating environmental impact of pipe-type cables

    Page(s): 314 - 318
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (376 KB)  

    Through a comprehensive and aggressive research program, the Consolidated Edison Company of New York, Inc. (Con Edison) has designed, developed and installed several new products to address the environmental impact of leaked dielectric fluid from pipe-type cable systems. These include online leak detection, leak location, retractable flow direction indicator, full stop joints and transition joints. This paper describes the application of the aforementioned products on the Con Edison underground transmission system View full abstract»

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Aims & Scope

Installation and operation of apparatus, equipment, structures, materials and systems for the safe, reliable and economic generation, transmission, distribution, conversion, measurement and control of electric energy.

Full Aims & Scope

Meet Our Editors

Editor-in-Chief
Wilsun Xu
Ph.D., P.Eng.
Dept. Electrical and Computer Eng.
University of Alberta
(9107 - 116 Street)
Edmonton, Alberta T6G 2V4 Canada
wxu@ualberta.ca
Phone:780-492-5965
Fax:780-492-1811