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Power Delivery, IEEE Transactions on

Issue 3 • Date July 1998

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Displaying Results 1 - 25 of 41
  • Application of regression models to predict harmonic voltage and current growth trend from measurement data at secondary substations

    Publication Year: 1998 , Page(s): 793 - 799
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (678 KB)  

    This paper presents the applications of regression models to predict the future growth trend of total harmonic distortions (THD) of 40 power transformers from field measurement data. The prediction values are important and can be used for transformer planning. Those transformers which feed different types of customers reveal different harmonic characteristics. While the linear regression model is suitable for harmonic voltage distortion, the nonlinear exponential regression model is better for current. All transformers' harmonic voltage distortions follow with harmonic current distortions, that is, feeder loads are harmonic sources. The prediction harmonic values of regression analysis are lower than that from the method of average spread rate. View full abstract»

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  • Investigation and mitigation of harmonic amplification problems caused by single-tuned filters

    Publication Year: 1998 , Page(s): 800 - 806
    Cited by:  Papers (20)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (688 KB)  

    This paper investigates the harmonic amplification problems in a plastics plant and the appropriate mitigation methods. Four single-tuned filters (LC filters) were installed to eliminate the harmonic currents from three 6-pulse rectifiers. However, after the capacitance reduction of some filter capacitors, the driving point impedance at the frequency of 8th order harmonic increased severely and the harmonic current of this order was amplified. There were many failures of the power filter capacitors. Field measurements and computer simulations are used to verify the disturbance problems. Finally, two high-pass damped filters are recommended to replace the original single-tuned filters. The amplification problems at some even-order harmonics can be avoided View full abstract»

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  • A new concept in construction of cable terminations for medium voltages

    Publication Year: 1998 , Page(s): 712 - 717
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (620 KB)  

    This paper describes a new concept in construction of cable terminations for medium voltages. Layers with a high permittivity and embedded electrodes (EEs) were used. Three groups of configurations were examined. In the first group, the layer of high permittivity was placed partly over the cable insulation and partly over the cable screen. In the second group, the high permittivity layer (HPL) was placed partly over the cable insulation and partly under the semiconducting material, connecting with the cable insulation screen. In the third group the cable screen was partly inserted into the HPL whose other part was placed over the cable insulation. The EEs were made in a shape of rings around the HPL. The rings were made either of copper tape or copper wire. Different positions of the EEs were examined. Numerical models of the cable terminations were used to monitor how the electric field changes as a function of the EE distance from the cable screen end. Finally, the new terminations were tested in a high voltage laboratory, according to the standards VDE 0278 and IEEE-404 View full abstract»

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  • HV-insulation of simple forms

    Publication Year: 1998 , Page(s): 849 - 854
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (588 KB)  

    The operational reliability of high-voltage power equipment depends mainly on the quality of its electrical insulation. The main characteristics determining insulating structure (IS) quality are: flashover voltage distribution (FOV); and voltage-time curve (VTC). It is currently thought that FOV follows the normal symmetrical law of distribution, while the VTC is inversely proportional to the degree function (so-called “hyperbolic type”). However, a series of IS discharge characteristics exist which differ significantly from the norm, both in flashover voltage quantity and in form. This paper discusses some results of IS investigations by the author in this area, based on research carried out in the 1980's in Russia at the RV Center of Siberian Research Institute of Energetic (Novosibirsk) View full abstract»

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  • Multimodular multilevel rectifier/inverter link with independent reactive power control

    Publication Year: 1998 , Page(s): 902 - 908
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (540 KB)  

    The feasibility of a DC link made up of multimodular, diode-clamped multilevel power converters to form the rectifier and the inverter has been studied in this paper. Equalization of the DC capacitor voltages is accomplished by auxiliary DC choppers sized at 10% of the current ratings. Real power control makes use of voltage angles as the control levers. Independent reactive power control on both sides makes use of voltage magnitude control. Digital simulations demonstrate the success of local controls. As the rectifier/inverter link plays a pivotal role in the unified power flow controller (UPFC) and the asynchronous DC link, the study has shown that multimodular multilevel versions of these FACTS controllers are feasible View full abstract»

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  • Model-based synthesis and suppression of transformer alarms in a control center environment

    Publication Year: 1998 , Page(s): 843 - 848
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (572 KB)  

    This paper presents the details of a prototype of an intelligent alarm processor called the Advanced Alarm Processor (AAP). The AAP uses model-based reasoning methods to synthesize and suppress power system alarms in the on-line environment. These model-based reasoning and processing methods are a new approach to intelligent alarm processing. The transformer model presented in this paper is a subset of the complete AAP which also processes power system, communications, protection, and substation alarms. The transformer module is used to demonstrate the reasoning and message-handling methods. Finally, the utility of the AAP is demonstrated through tests in which raw energy management system (EMS) input alarms are processed by the prototype to produce higher-level messages View full abstract»

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  • Comparative analysis of expulsion and current-limiting fuse operation in distribution systems for improved power quality and protection

    Publication Year: 1998 , Page(s): 863 - 869
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (644 KB)  

    This paper presents a comparative analysis of the effects of expulsion and current-limiting fuse (CLF) operations in distribution systems on power quality and power system protection. This analysis included field tests of both types of fuses on a distribution system in Florida, USA. To further analyze fuse effects on the voltage dip duration and spread of the overvoltages created during the fuse operations throughout the power system, computer simulations were also performed. Unique digital fuse models were developed for use with the EMTP/ATP program. This paper shows that CLFs improve power quality by supporting power system voltage during faults, reducing the voltage dip duration, and do not affect load operation. Additionally, CLFs reduce the fault let-through I2t View full abstract»

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  • Finite element computation of field and eddy currents of a system consisting of a power transmission line above conductors buried in nonhomogeneous earth

    Publication Year: 1998 , Page(s): 876 - 882
    Cited by:  Papers (3)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (748 KB)  

    The present work investigates the electromagnetic field and the eddy currents of a power system consisting of a faulted power transmission line above parallel conductors buried in nonhomogeneous earth. The electromagnetic field diffusion equation has been numerically solved, using the finite element method (FEM). Using FEM results, magnetic vector potential distribution in the cross-section of the parallel exposure, as well as eddy currents induced in all conductive parts, are calculated for various nonhomogeneous earth models. An analysis concerning the most important operational parameters in determining power transmission line influence is presented. Such parameters are the depth of the first earth layer, the resistivities of the different earth layers and the number of the mitigation wires View full abstract»

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  • A new approach for distribution feeder reconfiguration for loss reduction and service restoration

    Publication Year: 1998 , Page(s): 870 - 875
    Cited by:  Papers (55)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (484 KB)  

    This paper presents a new approach to solve the distribution feeder reconfiguration problem for loss reduction and service restoration. By using the proposed algorithm, a more efficient network configuration can be obtained to reduce loss. Three switching indices were defined in this paper. Branch voltage-drops and line constants were used with all the electrical constraints. Meshed networks were considered instead of the radial topology by closing all the tie switches. By considering only the largest switching index in each loop, this algorithm can reduce the number of feasible states drastically. The switching index can also be used for service restoration. Many tests have been run to show its effectiveness View full abstract»

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  • Calculation of the internal thermal resistance and ampacity of 3-core unscreened cables with fillers

    Publication Year: 1998 , Page(s): 699 - 705
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (572 KB)  

    The equations given in IEC 287 and in the Neher-McGarth paper for the internal thermal resistance of 3-core cables were developed for paper insulated cables. For such cables, it was assumed that the insulation and filler materials have the same thermal resistivities. In reality, in 3-core cables a variety of materials are used as fillers. The majority of these will have a higher thermal resistivity than the insulation. In this paper, a new formula is developed to compute the value of this thermal resistance taking into account the thermal resistivity of the filler. The effect of filler resistivity on cable ampacity is also discussed View full abstract»

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  • Fault and disturbance data requirements for automated computer analysis. Summary paper

    Publication Year: 1998 , Page(s): 735 - 737
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (224 KB)  

    This paper briefly describes the special publication, “Fault and Disturbance Data Requirements for Automated Computer Analysis”, prepared by working group III of the Relaying Practices and Consumer Interface Protection Subcommittee of the IEEE Power System Relaying Committee. The publication describes the analysis objectives and the data necessary to facilitate automated analysis View full abstract»

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  • Progress in step and touch voltage equations of ANSI/IEEE Std 80-historical perspective

    Publication Year: 1998 , Page(s): 762 - 767
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (608 KB)  

    This paper describes the evolution of safety criteria and the development of basic formulae for evaluation of the step and touch potentials in AC substations, from 1961 to the present time. Refinements proposed for the 1996 edition of ANSI/IEEE Std 80 are presented in a broader context of the continuing development of this popular IEEE Guide. Examples of a typical grounding design illustrate the difference in evaluation procedures given in the 1961, 1986 and 1996 (proposed) editions, and their practical impact on making the design safe View full abstract»

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  • Maximum step voltages of combined grid-multiple rods ground electrodes

    Publication Year: 1998 , Page(s): 757 - 761
    Cited by:  Papers (1)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    Expressions are suggested for assessing the maximum step-voltages and associated parameters of combined grid-multiple rods ground electrodes buried in uniform soil. The expressions proposed are successfully verified by comparison to exact computer calculations performed for a wide set of square and rectangular ground grids reinforced by ground rods distributed around the grid perimeter and within the grid View full abstract»

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  • Power quality regulation in Argentina: flicker and harmonics

    Publication Year: 1998 , Page(s): 895 - 901
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (624 KB)  

    Argentina has developed explicit power quality regulations. At the beginning of the 1990's, public distribution companies were privatised in the area of Gran Buenos Aires. Detailed regulations regarding continuity of supply and voltage profile were then established. Regulations regarding voltage disturbances were established at the end of 1996, for the purpose of controlling the level of disturbance in the power networks and users disturbance injection, particularly regarding harmonics and flicker. This paper describes these late developments together with a practical example of their application. The bases of these new regulations are international standards that have been adapted to form a set of reference levels, emission limits and measurement and control procedures. These points, together with a economic penalty system, conform one of the most advanced regulatory schemes for power quality in public supply networks View full abstract»

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  • Application of vector fitting to state equation representation of transformers for simulation of electromagnetic transients

    Publication Year: 1998 , Page(s): 834 - 842
    Cited by:  Papers (27)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (900 KB)  

    This paper presents an efficient methodology for transient modeling of power transformers based on measured or calculated frequency responses. The responses are approximated with rational functions using the method of vector fitting. The resulting model is dynamically stable since only negative poles are used, and input-output stability is assured by a novel adjusting procedure. The methodology is used to formulate two different transformer models: (1) a full phase domain model realized column-by-column, and (2) a model utilizing modal diagonalization. The application of the models is demonstrated for a 410 MVA generator step up transformer View full abstract»

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  • The use of rational B-spline surface to improve the shape control for three-dimensional insulation design and its application to design of shield ring

    Publication Year: 1998 , Page(s): 962 - 968
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (544 KB)  

    In this paper, a three-dimensional algorithm for the insulation design of the high-voltage equipment is presented. In general, the insulation design consists of two steps. One is the electric field calculation. The other is the correction of the shape of the electrode or the insulator to be designed. The main point of this paper is the introduction of the rational B-spline to improve the shape control for the insulation design. In former research, the correction of a shape is made by direct control with the nodes on the shape. This required many design variables and causes the discontinuous curvature of a designed shape. These problems can be dealt with by the indirect control which is one of the useful properties of the rational B-spline. The use of rational B-spline results in the reduction in the number of design variables and guarantees the smooth curvature of the designed shape. The proposed algorithm is applied to the design of the shape of the shield ring which is installed in the joint of transmission lines and the insulator and has been designed by the method of trial and error. The combination method of charge simulation method (CSM) and surface charge simulation method (SCSM) is used to calculate the three-dimensional electric fields produced by this system View full abstract»

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  • A transformerless high-pulse static synchronous compensator based on the 3-level GTO-inverter

    Publication Year: 1998 , Page(s): 883 - 888
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (556 KB)  

    This paper presents a high-pulse shunt compensation scheme based on the three-level GTO-inverter which requires a minimal magnetic interface. The scheme utilizes small inductors, rather than phase-shifting transformers, for combining several three-level inverters to a high-pulse static synchronous compensator. The resulting arrangement has an output harmonic profile comparable to a 48-pulse inverter. A suitable control scheme is developed for the proposed compensator which provides smooth VAr control for the network. Simulation studies are presented in the paper, which demonstrate that the proposed design could decrease the complexity of advanced compensation schemes View full abstract»

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  • Overhead electrical transmission line galloping. A full multi-span 3-DOF model, some applications and design recommendations

    Publication Year: 1998 , Page(s): 909 - 916
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (888 KB)  

    A full multi-span three-degree-of-freedom (3-DOF) iced power transmission line model is presented. This new model is applicable for describing the galloping phenomena of both single and bundle lines, for performing static and dynamic analysis, and predicting the galloping behavior of iced power transmission lines, as well as for performing checks against field experience. Some applications for overhead power transmission lines design are detailed. Some original recommendations for the design of multi-span bundle configurations are also proposed View full abstract»

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  • Distribution automation communication infrastructure

    Publication Year: 1998 , Page(s): 728 - 734
    Cited by:  Papers (9)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (612 KB)  

    Communication is very important to distribution automation (DA) because DA relies on the coordinated effort of various elements in the system. Many communication systems have been designed for DA so far. However, most of these communication systems use proprietary (vendor specific) protocols and are for individual instead of all DA functions. Thus, there has long been a great need for an open and integrated communication system capable of supporting all DA functions transparently. This paper presents a new communication infrastructure, PS-TCP/IP (power system TCP/IP), for all DA communications including customer services. PS-TCP/IP can support all DA functions transparently because it follows three design principles. First, each network element (NE) involved in DA communications, including customer meters, is assigned a unique network-layer address which corresponds to their relative position in the power distribution network. Second, all NEs can communicate with each other as long as they encapsulate their data in a standard-format “IP datagram”. Third, any ISO layer 1 and 2 protocols can be incorporated easily. PS-TCP/IP's design follows ISO's layered approach. This means that the structure of the communication system is independent of that of any DA function's, thus creating a truly open and transparent communication environment for all DA functions View full abstract»

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  • Efficient ground grid designs in layered soils

    Publication Year: 1998 , Page(s): 745 - 751
    Cited by:  Papers (13)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (628 KB)  

    A detailed analysis of the effects of ground grid configuration on grounding performance has been carried out for uniform and horizontally stratified soils with multiple layers. The results of the analysis reveal that the most efficient and cost-effective design is highly dependent on soil structure type and characteristics. In the absence of ground rods, grounding grids with uniform mesh size are quite efficient in soils having a thin (relative to grid size) high resistivity (relative to the lower layers) top soil, while grids with small mesh size at the periphery of the grid provide optimum performance in uniform soils and soils with low resistivity top soils. Ground rods were found to be effective only when a significant portion of their length is in contact with a low resistivity soil, as expected View full abstract»

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  • The application of ultra-high-frequency partial discharge measurements to gas-insulated substations

    Publication Year: 1998 , Page(s): 777 - 782
    Cited by:  Papers (33)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (608 KB)  

    This paper deals with the application of the ultra high-frequency method (UHF-method) for the detection of partial discharges (PD) in gas-insulated substations (GIS). First, a review of the GIS-relevant part of the theory of electromagnetic wave propagation in the UHF-range (300 MHz-3 GHz) is given. New information considering the attenuation due to reflections of UHF signals at spacers is presented. For the sensors used to pick up the UHF signals inside the GIS, a new description of an antenna valid in the UHF range is introduced. The second part of this paper presents measurements with the UHF method to compare the sensitivity to the conventional PD detection method according to IEC-270. Practical conclusions are drawn from these new results for the application of the UHF method for onsite testing and online PD monitoring of GIS View full abstract»

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  • Study of propagation phenomena of partial discharge pulses in gas insulated substation

    Publication Year: 1998 , Page(s): 768 - 776
    Cited by:  Papers (8)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (1104 KB)  

    This paper describes the results of tests and discussions carried out to develop a system for monitoring partial discharges generated in gas-insulated substations (GIS). They include the propagation characteristics and the mechanisms of partial discharge pulses in the GIS, the results of computer simulation, and the results of comparisons with previous tests to verify the partial discharge locating method View full abstract»

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  • Construction features and environmental factors influencing corrosion on a self-contained fluid-filled submarine cable circuit in Long Island Sound

    Publication Year: 1998 , Page(s): 677 - 682
    Cited by:  Papers (2)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (852 KB)  

    A 345 kV self-contained fluid-filled cable circuit was installed in an environment where corrosion of the armor may occur. To better understand the conditions that may result in corrosion, stray currents in the cable end zones and in the middle (submarine) of the circuit were measured, and cable samples were analyzed to determine the electrochemical activity of the cable's outer layers. The results of the project revealed that electrolytic corrosion would affect the semiconductive polyethylene if sufficient stray current density (greater than 0.15 A/m2) was induced by stray currents which were present in Long Island Sound where the cables are installed. Measurements revealed stray current densities in excess of this level towards one end of the cable route. Various other considerations for corrosion are also discussed View full abstract»

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  • Utilization of cable capacitance in GTO-HVDC transmission

    Publication Year: 1998 , Page(s): 945 - 951
    Cited by:  Papers (7)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (492 KB)  

    The voltage-source, GTO-HVDC stations require capacitor banks at their DC terminals for two purposes: (i) filtering of the GTO switching noise and (ii) voltage support. This paper examines the feasibility of exploiting the capacitance of submarine and/or underground cables, thus offsetting some of the cost. It is shown that the capacitance of cable length as short as 10 km can significantly reduce the total harmonic distortion (THD) of the DC voltage from 7.76% to 2.26%. However, the THD of the DC current is of the order of 18%. An inductor of 20 mH (0.106 p.u.) is sufficient to reduce the current THD to 7%. The cable is modeled as L-R-C π section representation of the transmission line (1-section per km). The results are obtained by digital simulations (Matlab/Simulink) View full abstract»

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  • Study on an after-laying test for a long-distance GIL

    Publication Year: 1998 , Page(s): 718 - 727
    Cited by:  Papers (5)
    Save to Project icon | Request Permissions | Click to expandQuick Abstract | PDF file iconPDF (912 KB)  

    Technologies for the after-laying test of long-distance SF6 gas insulated transmission line (GIL) have been developed for the detection of partial discharge (PD) and contact defects. We constructed a long (168 m) test line in a deep tunnel and clarified the propagation characteristics of PD signals through the GIL as well as the spatial sensitivity and S/N characteristics of PD sensors for locating metallic particles. We have also proposed the application of a fiber-optic temperature distribution sensor for locating contact defects and confirmed the validity of this sensor for the GIL test line 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.

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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