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Electricity Distribution, 1989. CIRED 1989. 10th International Conference on

Date 8-12 May 1989

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Displaying Results 1 - 25 of 112
  • The design of overhead electric lines for improved reliability

    Page(s): 196 - 199 vol.3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (248 KB)  

    Traditional overhead line design in the UK has involved calculation to show compliance with requirements which guarantee stress limitations in components under specific loading conditions. The approach is described mathematically as deterministic and the minimum requirements which limit stress (the Factor of Safety) and the loading conditions under which these must be met have been uniform across the country and have been set by statute. The author describes the production of a new national standard for high voltage single circuit wood pole lines which adopts a matrix approach to design, matching site weather parameters with component capabilities, to specify line designs based on common components and arrangements for use throughout the UK. The author focuses attention on some of the more important aspects of the performance base now being considered and upon the flexibility inherent in and the possible future usefulness of this matrix approach View full abstract»

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  • The results from a major load management project

    Page(s): 431 - 436 vol.5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (396 KB)  

    In Denmark a large load management investigation comprising 500 customers has been carried out. The investigation lasted 11/ 2 years. The authors describe the basis and the results of the investigation. The results show that multi-rate time-of-day tariffs bring about significant changes of behaviour, particularly with domestic customers, but also significantly with industrial and commercial customers. Over this period, tests with bidirectional communication over the power supply network were made. These showed that this solution is technically possible, if a repeater is placed at intermediate substations View full abstract»

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  • Using the common benefits from land information systems in the planning of a geographic facility management system

    Page(s): 505 - 509 vol.6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    In Denmark interest in digital geographical cable and pipeline registration systems arose at the end of the 1970s in connection with the establishment of the natural gas distribution network from the North Sea. Cooperation between cable and pipeline owners and public authorities was further developed in the beginning of the 1980s. The author gives a closer description of the results of these cooperation initiatives, including the common national reference system; cooperation models for the establishment of a common basic digital map; the development of a common system-model conception for cable and pipeline registration; and standards for the exchange of cartographical data. The authors describe the common basis for the establishment of a cable and pipeline registration system and how NESA, the largest Danish electric utility, has benefited from this basis in connection with the introduction of its own system View full abstract»

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  • International cable fault statistics on synthetically insulated MV-cables

    Page(s): 200 - 206 vol.3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    The authors' aim to establish fault statistics for medium voltage cables with extruded insulation in the voltage range 10-30 kV. Four different groups of organic insulating materials have been considered; linear polyethylene (LDPE), cross-linked polyethylene (XLPE), ethylene-propylene rubber (EPR) and polyvinylchloride (PVC). The procedures for voltage tests on cables provide a serious topic for discussion. The authors explain the present cable testing procedures, giving a critical assessment in some parts, and describe new developments in this field View full abstract»

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  • New types of MV distribution overhead lines and LCC-analysis as a method for selecting type

    Page(s): 185 - 189 vol.3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    Due to public demands for better reliability in electric power distribution, Swedish utilities have worked for better service performance in medium voltage overhead lines. The demands have resulted in the development and standardization of new MV overhead line systems such as self-supporting MV ABC cable systems, ACS AXUS and MV covered bare line systems. LCC-analysis, described by the authors, shows that the usual bare line constructions should not be chosen as a matter of routine. The most economic solution over life time for MV overhead line will in many cases be self-supporting ABC-cable (ACS AXUS) or covered bare lines View full abstract»

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  • Optimization of HV/MV substations: experiences and special topics

    Page(s): 436 - 440 vol.5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    On the basis of experience obtained in many years of engineering and contracting conventional and GIS substations in many countries around the world, the authors summarize the most important aspects relevant to HV/MV substation projects. Special emphasis is placed on EDP tools to facilitate project execution and the authors also examine both the new trends encountered in the technical specs imposed by the client and new trends that are due to environmental conditions View full abstract»

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  • Proposal for the display of medium voltage distribution networks with intermeshed structure on VDU in network control centres

    Page(s): 360 - 364 vol.4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (344 KB)  

    The authors discuss the requirements for the display of intermeshed distribution networks. They then discuss the different methods of display: overall view diagram, detail diagrams, display of windows, and the use of colour. Examples are given and the hardware and software briefly described View full abstract»

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  • Model for load simulations by means of load pattern curves

    Page(s): 545 - 549 vol.6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (260 KB)  

    A growing need has been felt in Sweden for better knowledge of the loads in the power distribution networks and for better load information processing methods. The Association of Swedish Electric Utilities has therefore initiated a nationwide load data measurement programme and research project aimed at developing a new load information processing method. On the basis of the measurements, statistical demand curves have now been produced for several different customer categories. To facilitate the use of these calculated demand curves, a forecast program has been developed. The demand curves and associated forecast program are available for VAX computers and IBM PCs. The objective has been to make the forecast program as easy as possible to use. The only data that has to be entered is information which is normally available within the electricity supply utility. The authors discuss the analysis and forecast models View full abstract»

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  • Handleability of polymeric insulated cables

    Page(s): 228 - 232 vol.3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    The many different types of polymeric insulated medium voltage cables on the market today have very different properties as regards handleability. Some designs are very easy to handle in laying and installation operations. Others are very rigid and elastic and thus tempt to rough handling. The objective of carrying out the work described by the author is the development of a measuring method for the evaluation of properties of the individual cable designs in respect of handleability to enable selection of the optimal type of cable for any purpose View full abstract»

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  • Decentralized data acquisition and processing system for power supply network planning and operation

    Page(s): 494 - 498 vol.6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (752 KB)  

    The planning and operation of power supply networks require readings of electrical quantities. The number of these readings and their statistical evaluation necessitate a practical measuring, recording, processing and filing system. The new system described meets this requirement. It comprises standard units of equipment; exchangeable `memory-blocks' are installed for storing the programs for processing the recorded values. The software merely requires a personal computer for the programming, analysis and filing of the recordings. The display program can be adapted to requirements. The first experiences gained with this system are conclusive; the potential of being able to process the values as soon as they are measured is appreciable View full abstract»

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  • Optimum balance between structural and operating investments for the development of radial MV networks

    Page(s): 535 - 539 vol.6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    Quality can be improved by upgrading the networks with major investments and operating devices. A method can be found to locate the ideal balance between structural and operating investments, if the duties of the new equipment are clearly defined and if a value can be given to customer inconvenience resulting from poor quality. This process comprises two stages for which EDF has developed several calculation models. The GENARBRE model is used to build up a library of fundamental laws on arborescent structures. The OSCAR program is a static model giving the main structural characteristics; density of HV/MV substations, number of feeders, dimensions of feeders for a given fixed level consumption. SIERRA is an arborescent system development simulator used to select the upgrading methods and dates over a long period View full abstract»

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  • The development of an integrated information system to support the Engineering Department of electricity utilities

    Page(s): 550 - 557 vol.6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    The Distribution Engineer in a UK Area Electricity Board is being required to respond to increased pressures from the technical economic and customer demands of his work. The implications of this shows that the engineer will need access to data not easily available to him. Furthermore this new data, to be of value, has to be properly integrated with existing engineering computer applications. The authors describe their work to develop an integrated database that would fully support the needs of the Engineering Department. They discuss four main aspects of their work: identification and definition of the requirements of an integrated database; developments in information technology that made the development of the database a practical proposition; the shape and structure of the designed database paying particular attention to plant and circuits; and the use of the database and a description of the benefits it can be expected to provide View full abstract»

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  • Transformer loss-of-life calculation using a computerized probabilistic method

    Page(s): 57 - 61 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (372 KB)  

    A personal computer program has been developed to calculate the loss-of-life of distribution transformers. It assists the user in choosing the transformer rating that is appropriate for various loading and temperature conditions. The transformer loss-of-life program (LOSLIF), employs a Monte Carlo technique to calculate the probabilistic distribution of loss-of-life per year, based on inputs which represent realistic changes in ambient temperature and secondary load. The required temperature and load statistics are stored in databases which accompany the program and may be modified by the user. Example calculations have shown that the loss-of-life predictions from this probabilistic program are less conservative and more realistic than those provided by deterministic methods. The LOSLIF program can also be used to determine whether it is acceptable to increase loading on an existing transformer, and thus defer a costly change-out View full abstract»

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  • Evolutions of remote control systems for MV networks

    Page(s): 351 - 354 vol.4
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    For many years, Electricite de France has been using a wide range of computerized remote control systems (SIT 1, 2, 3, 4) whose technical characteristics have been adapted to the great variety of needs of its distribution centers. The authors deal with the evolutions of the systems and the motivation behind them. First of all, they present the range of possible functions of a remote control system in view of substantial improvements in the quality of service. The principal new functions concerned led to the implementation, in the remote control system, of a database representing not only the units under remote control, but also the electrical links connecting them. The authors describe an architecture which will guarantee the ability of the system to be developed in several steps. It allows pre-programmed switching sequences to be implemented, and then progressively provides all functions for restoration purposes which lead to automatic control of the MV network View full abstract»

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  • The influence of a DC test voltage on the AC performance of new and old XLPE cables

    Page(s): 233 - 237 vol.3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (480 KB)  

    The main purpose of this work was to check if DC testing of XLPE cables could be harmful to the insulation. Tests performed both on new and aged Rogowski objects and cable samples showed no detrimental effects of DC testing. Some results supported the hypothesis that if a breakdown occurs during DC testing of aged XLPE insulation the rapid collapse of voltage might reduce the dielectric strength of the remaining insulation. In samples where the longest vented water trees were found to penetrate more than 50% of the insulation wall, the DC breakdown strength was found to be 1.4-2.2 times higher than the effective AC breakdown voltage View full abstract»

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  • Compact lines for urban areas: a new solution

    Page(s): 190 - 195 vol.3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (840 KB)  

    After an introduction which summarizes the main requirements of compact power lines for urban and suburban areas, the authors describe a new solution which meets the above requirements at low cost. This new solution considers towers with a pivoted base, free from longitudinal resistance (bidimensional structures). The frame type towers (triangular trestle) are made of a few slender members in cold formed `tubular-like' sections. Details on line and towers conception and behaviour are given together with the analyses performed through mathematical models, dynamic reduced scale model, and full scale tests. The authors finally refer to the construction of a double circuit 132 kV line of the new type in a Florence suburb. This line was commissioned in June 1987 and is currently providing a very successful operating experience View full abstract»

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  • Substation protection and control-a look into the future

    Page(s): 131 - 136 vol.2
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (428 KB)  

    The authors describe the design of a proposed integrated microprocessor based system capable of carrying out the control and protection functions currently undertaken in distribution substations, together with possible additional functions to assist in the better management of the substation and power system as a whole View full abstract»

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  • A new relational database with fully integrated computer graphics and network optimizations and calculations

    Page(s): 510 - 514 vol.6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (352 KB)  

    A new computer software package has been developed by Sydkraft, Sweden. The package is intended for the design and management of power distribution networks. It can be split into three modules to be used separately or as parts of an integrated system: a relational database to store all information needed for the calculations; optimal design of new networks and optimal reinforcement of existing networks; and day-to-day calculations for management of existing networks. Interactive computer graphics is used as much as possible to make the system easy to use and yet powerful and efficient for various kinds of users. Much effort has been put in developing the data model that has been realized in the database. Both the technical and the graphic information have been integrated in the database. The authors describe the structure of the system, network documentation, design and management, the man/machine system, mapping, and hardware View full abstract»

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  • Corrosion attack in midspan joints in ACSR transmission conductors

    Page(s): 259 - 261 vol.3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (124 KB)  

    In conjunction with the investigation of midspan transmission line conductor joints that have been dismantled because they exhibited excessive resistance, it was discovered in most cases that severe corrosion attack had occurred in them. The attacks were concentrated in the areas where the steel core enters the steel joint sleeve. Corrosion was discovered in conductor joints on 130 kV to 400 kV lines. Various methods of inspection have been tested to determine the extent of this corrosion and protect conductor joints from further attack View full abstract»

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  • Load management and dynamic stability improvement in industrial networks by battery energy storage plant

    Page(s): 397 - 401 vol.5
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    Battery storage plants (BSP) are either already in operation or under planning in many utility and industrial companies. The main fields of their application are the improvement of frequency control in island networks, voltage maintenance in radial feeder networks, and load control. In industrial networks with a large component of motoric load, BSP can help in the fast balancing of active and reactive power after network separation. The authors show that problems of reacceleration of motors and damping of power oscillations of generators can be coped with equally well View full abstract»

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  • Control methods for the distribution overhead line network

    Page(s): 540 - 544 vol.6
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    The authors describe the background and the reasons why a more automatic network operation during disturbances is advantageous. The aim of network operation to minimize the interruptions concerning load and time. To obtain this, different control methods are adopted. The control methods are either remote or local, operated manually or automatically. The most common method is local manual operation of the sectionalizing switches. To obtain a quicker, but more coarse sectionalizing, some of the line switches are remote controlled. By introducing local automatic control of the sectionalizing switches, a very quick sectionalizing of the fault, and a re-energizing of the healthy network is obtained. The different control methods are evaluated by comparing the investment costs to the social benefits of the reduction in nondelivered power and energy View full abstract»

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  • XLPE insulated MV cables; service experience, actual problems and prospects for the future

    Page(s): 223 - 227 vol.3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (448 KB)  

    For some ten years now a single phase cable of simple structure has been used in the Belgian medium voltage power network. The cable consists of an aluminium conductor, an internal extruded semiconductor, XLPE insulation, an external extruded easy strip semiconductor, a copper wire metal screen, and red-coloured outer jacket in reinforced PVC. This type of cable has until now given complete satisfaction. The first cable fault in a three-phase network of more than 1500 km in service since 1979 mainly in a 15 kV network, has not yet occurred. The experiences being good, but inspired by several publications abroad, Belgian utilities decided to carry out a series of life tests of the same kind as those that some years earlier had been carried out on paper-insulated cables. The authors describe these tests which revealed that the intrinsic behaviour of the insulation itself was good, but there is a risk of corrosion on the copper screening View full abstract»

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  • Improvement of the XLPE-insulated distribution cables and development of the hot line cable monitoring systems

    Page(s): 284 - 291 vol.3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    Crosslinked polyethylene insulated power cables (XLPE cables) were first used for 6 kV distribution lines in Japan in 1959. Since then, XLPE cables have been widely used in transmission and distribution systems because of their many advantages in comparison with oil-filled cables, such as good electrical properties and easy-maintenance and handling. XLPE cable, however, involves a problem of water tree deterioration. Water treeing began to be an actual problem in about 1967, mainly with 6 kV XLPE cables for power distribution, and a solution has since been urged. The authors introduce actual instances of water tree deterioration and describe some improvements to the cable which may solve the problem. Development of an instrument that enables live line diagnosis of the deterioration is also described in detail View full abstract»

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  • Measurement of touch voltages on 25-kV underground distribution systems

    Page(s): 238 - 242 vol.3
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (496 KB)  

    Underground distribution lines in Canada are installed in duct banks with manholes placed at regular intervals for easy installation of the line hardware and ready access for maintenance purposes. During work in these manholes, touch voltages may occur on the line under repair as a result of a fault on another line. Tests were performed on a 25 kV system to measure the level of such voltages and to validate a computer model. The maximum touch voltage measured was 220 V. Over 6000 system configurations were examined in a computer study which showed that the touch voltage appearing at the work site can reach as much as 1500 V in some cases, although operating experience shows that the probability of such high voltages is very slight View full abstract»

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  • Service experience with epoxy resin for both insulation and construction material and its application in a future design of insulation enclosed switchgear

    Page(s): 42 - 46 vol.1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (508 KB)  

    The authors show that epoxy resin is an excellent insulation material which leads, provided it is properly designed, to safe and reliable switchgear. They then describe the use of epoxy resin as an insulation and construction medium, in a new design of substation switchgear for 12 and 24 kV. A brief description is given of the overall design of the new installation. Special attention is then paid to the characteristics of the insulation material, such as dielectric and mechanical requirements, temperature management and appropriate tests. Finally, the area of application of the relevant switchgear is specified View full abstract»

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