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AC and DC Power Transmission, 1991., International Conference on

Date 17-20 Sep 1991

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Displaying Results 1 - 25 of 77
  • Planning and design studies for the far North Queensland Georgetown and Normanton AC transmission scheme

    Publication Year: 1991 , Page(s): 44 - 49
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (400 KB)  

    In Australia remote areas of Far North Queensland have relied for many years on small local diesel powered stations for electricity supply. This is about to change with the commencement of construction by the Far North Queensland Electricity Board (FNQEB) of a transmission line and substations to this region. Work is planned to be completed by mid 1992 . The authors describe planning studies for this project from early feasibility studies in 1984 to the detailed design which is about to be completed View full abstract»

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  • Reactive compensation using static VAR compensators-a planning case study using security constrained techniques

    Publication Year: 1991 , Page(s): 50 - 54
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (276 KB)  

    Optimal power flow programs have been widely advocated for voltage performance planning. The National Grid Company (NGC), however, has found that they do not yet address the particular problems encountered on its transmission system. The author illustrates the nature of these problems which require the use of security constrained techniques and describes a method which has enabled a practicable minimum compensation investment strategy to be determined. Recently commissioned compensation devices in the area include 180 MVar mechanically switched capacitors (MSCs) at Indian Queens and Mannington and a 150MVar static VAr compensator (SVC) at Exeter. A further stage of reactive compensation planning for this area has been recently completed and two additional 150 MVar SVCs authorised for commissioning in 1992. The author outlines the compensation planning process as a case study View full abstract»

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  • City versus country-a comparison of two types of standardised SVC for the National Grid in England

    Publication Year: 1991 , Page(s): 248 - 254
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (500 KB)  

    The authors discuss the design and operational differences of static VAr compensators located in Exeter and St. John's Wood, London. Perhaps the most obvious and significant difference is the smaller site area available, which requires a more compact design of SVC. The concept of a walk-around site and independent maintainability of each main component with other equipment still live and in service was retained in the city by adopting a different design of SVC system. The second contrast is in respect of the rating and duty of the SVCs. In each case the capability for emergency operation to support the system against undervoltage or to control overvoltages is required, but for the application within the heavy load area of the city, the float condition is used much less and the enhanced induction rating of 100 MVAr is expected to be used for prolonged periods on a daily basis View full abstract»

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  • Static VAR compensator from Coxipo Substation (Brazil)-comparison between computer simulations and field tests

    Publication Year: 1991 , Page(s): 301 - 306
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    The authors show a comparative analysis between field tests during commissioning of the static VAr Compensator (SVC) from Coxipo Substation (-50/+70 MVAr), and the computer simulations using a digital model developed by means of the EMTP (TACS) program. They also present some details of modelling of the SVC. The model is useful for: transient studies whenever the SVC is involved; the possibility of analysing and implementing of any modification in the SVC control system; and the modular feature of this model makes it flexible, allowing its application in studies for specification of new SVC configurations View full abstract»

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  • On experience in development, designing and construction of AC high and ultra high-voltage and higher actual power transmissions

    Publication Year: 1991 , Page(s): 232 - 234
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (144 KB)  

    Power transmission characteristics can be drastically improved by application of the development made at the Leningrad State Technical University. It consists of phase splitting into a greater number of constituent wires, accompanied by optimization of their relative position in space (both at the support and in the span). In this case, the electric intensity on the surface of all wires of all phases should be close to the maximum permissible value to limit corona discharge. Under these conditions, the actual power of the line increases proportionally with the number of wire splittings and diameter. The wave and inductive impedance of the line decreases correspondingly. The author discusses the application of the method to three power lines: Leningrad-Moscow 750 kV line; the Pskov SDEPS-Novasokolniki 330 kV line; and the Boguchan SDEPS-Kansk Station 500 kV line View full abstract»

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  • Environmental aspects of 800 kV line design in India

    Publication Year: 1991 , Page(s): 205 - 210
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (332 KB)  

    The authors discuss the impact of 800 kV lines with respect to ecological and environmental aspects, electrostatic and electromagnetic fields, radio and television interference, audible noise, and associated possible biological effects, on human beings and flora and fauna. In particular the authors discuss tree top clearances of the power lines, electric field effects, and corona performance including TVI and RFI View full abstract»

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  • Design studies for the S. Tome' nack-to-back HVDC converter

    Publication Year: 1991 , Page(s): 177 - 182
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (384 KB)  

    The Sato Tome' back-to-back converter is planned as the second HVDC link to asynchronously connect the Argentina (50 Hz) and Brazil (60 Hz) transmission systems. From the date of commissioning to the year 1996, the S. Tome' converter will be connected to the respective AC networks via single AC ties. In 1996, plans call for a second 132 kV line on the Argentina side, thereby interconnecting the two frequency converters. The purpose of this paper is to describe the technical specifications, engineering studies, and final designs for the S. Tome' frequency converter. Specifications called for a number of special control features to assure a versatile operating strategy View full abstract»

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  • Harmonic domain representation of thyristor controlled reactors

    Publication Year: 1991 , Page(s): 404 - 406
    Cited by:  Papers (4)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (184 KB)  

    A new TCR (thyristor controlled reactor) model has been developed by linearising the state equations of the TCR in the harmonic domain. The resulting equations can be interpreted as a harmonic Norton equivalent. They can also be represented in the multiphase harmonic domain frame of reference, where they could combine easily with the frequency dependent admittances of the transmission network and with other linearised components such as saturated transformers, rotating machinery, electric arcs and power convertors. The linearised TCR model is completely general. It is suitable for assessing TCR filtering equipment requirements and for harmonic penetration studies View full abstract»

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  • Numerical simulation of the Cross Channel HVDC link during AC system faults. Comparison with site test results

    Publication Year: 1991 , Page(s): 313 - 318
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    The detailed knowledge of the control and regulation circuits installed in the French end of the Cross Channel HVDC link has been used to realize a numerical model of the interconnection, the aim of which is to predict the behaviour of the combined DC link/AC system in case of various AC, fault scenarios and to avoid expensive field tests. The following validation oscillograms have shown that the simulations made with this model can be used with confidence. The fidelity of the results delivered could probably be greater by using models of higher precision with respect to their nonlinear or frequency dependant characteristics (magnetising current of transformers, losses of the various components etc.) The EMTP model of the Cross Channel link does not pretend to replace an HVDC simulator regarding the facility of exploitation as the preparation and running of simulations are long and demand a great amount of calculation time View full abstract»

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  • Active and reactive power controls for the Gezhouba-Shanghai HVDC transmission scheme

    Publication Year: 1991 , Page(s): 279 - 284
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (340 KB)  

    The ±500 kV, 1200 MW HVDC transmission scheme, the first in China, interconnects the Central and Eastern China regional power systems over a distance of 1045 km. The scheme, known as GESHA, was commissioned in two stages in 1989 and 1990 respectively. The authors present a brief description of the HVDC transmission scheme and its principal modes of operation and the operating environment of the interconnected AC systems. Then, they focus on the novel control strategies for active and reactive powers adopted by the HVDC scheme to match the different requirements of the AC systems. Reactive power and AC voltage controls using the HVDC converter terminal-the first application in HVDC transmission systems-is explained in detail. Results of field tests made during the commissioning phases of the scheme to demonstrate these control features are also presented View full abstract»

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  • The integration of new valves and controls to Nelson River HVDC Bipole 1

    Publication Year: 1991 , Page(s): 147 - 152
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (440 KB)  

    The Nelson River HVDC transmission system in Manitoba presently consists of two bipoles. Bipole 1 has a rating of 1670 MW at ±463 kV and transmits this power from the northern terminal at Radisson Station over a distance of approximately 900 km to the Dorsey terminal near Winnipeg. Bipole 2 has a rating of 1800/2000 MW at ±500 kV and transmits this power from the Henday Station, some 40 km downstream from Radisson, also to the Dorsey terminal. Bipole 1 which is the subject of this article, was the last of the HVDC links to be commissioned using mercury arc power convertor valves. The rating of 154.5 kV, 1800 Å per group is the highest used for mercury arc convertor valves View full abstract»

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  • System variable evaluation with digital signal processors for SVC applications

    Publication Year: 1991 , Page(s): 255 - 260
    Cited by:  Papers (1)  |  Patents (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (320 KB)  

    The practical implementation of digital signal processors (DSP) is illustrated by describing a voltage regulator which is used to control a static VAr compensator (SVC). Extensive transient network analyser tests showed that signal processors used for system voltage evaluation yield results that are entirely equivalent to those obtainable by analogue methods. Digital methods necessarily and inevitably involve the sampling of analogue variables. Characteristics of the data sampling system must be taken into account at the design state. This applies to analogue signal bandwidth limitation, analogue to digital conversion, accuracy and the measures required to handle the extra delays involved. The digital implementation is described from the standpoint of the most important system value, i.e. the system voltage. In addition to processing the system voltage, digital technology is also used for reactive power calculation, synchronization voltage filtering, frequency measurement and the evaluation of system voltage for protection purposes View full abstract»

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  • HVDC valve with light-triggered thyristors

    Publication Year: 1991 , Page(s): 159 - 164
    Cited by:  Patents (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    In high voltage direct current (HVDC) applications, the AC/DC thyristor power converter is subjected to very high voltages and each valve in the converter bridge must be able to withstand several hundred kV. As the voltage capability of a single thyristor is limited to less than 10 kV. Necessary firing and protection facilities at the thyristor level must therefore be energized by current coming from the valve itself at the same level. Furthermore, triggering signals between these facilities and the control system at ground potential must be transmitted optically. Though a rather sophisticated but reliable solution based on a compact thyristor control unit (TCU) has been evolved for conventional electrically triggered thyristors (ETTs) direct optical triggering of the thyristor would be advantageous to simplify the valve electronics and possibly further improve converter reliability. The object of this presentation is to compare different circuit configurations based on light-triggered thyristors and to summarize laboratory and field test experiences of the chose solution. Some comments will also be made on a new design utilizing recent improvements in optical components View full abstract»

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  • Multiterminal HVDC system control using a distributed computing technique

    Publication Year: 1991 , Page(s): 114 - 119
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (280 KB)  

    HVDC schemes are poised for a more significant level of acceptance in the large power transmission grid because of the proven experience that has been accumulated over many years with two terminal systems. Recent trends indicate that more multiterminal HVDC systems are emerging as an option for expansion. Derivation of the control strategy for a multiterminal case, however, requires the handling of a significantly larger number of state variables. There is also the need to optimize system performance taking into account the total `control effort' to be used. All this implies a need for more demanding computational power which will increase out of proportion to the increase of terminal numbers in the online control of multiterminal systems. The essence of the work presented in this paper is to get around this problem by adopting a distributed computing approach. The various features used to establish this distributed computing environment and the employment of this technique to facilitate the system controller in generating and coordinating commands for the overall optimal control of the AC-DC system are illustrated in the paper View full abstract»

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  • Integrating optical communications within the power network-the practice

    Publication Year: 1991 , Page(s): 211 - 219
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (588 KB)  

    Because of the availability of `all dielectric self supporting optical cables' (ADSS) offering secure interface free operation, some power utilities are now installing various forms of optical communications on their overhead transmission network, weather on AC of DC lines, for both power system control and general telecommunications duty. Based on successful trials on ADSS systems on overhead lines, East Midlands Electricity has embarked on a programme of installing a network of overhead optical cables to support and supplement its existing digital radio network. The authors discuss the application and experiences of one particular type of ADSS optical cable installed on existing 132 kV tower lines and include a description of the severe snow storms experienced by the midlands region of the UK in December 1990. Recommendations regarding standards for component design, system security future expectations and further development work in ADSS optical cable technology are addressed View full abstract»

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  • A benchmark model for HVDC system studies

    Publication Year: 1991 , Page(s): 374 - 378
    Cited by:  Papers (44)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (240 KB)  

    The idea of establishing a benchmark system to study certain phenomena is not new. However this is a first attempt to create a common reference for HVDC studies, especially one related to control strategies and recovery performance. Another benefit that results from such a standard system is the possible comparison of different simulation methods and results. The authors discuss assumptions and reasons for selecting the HVDC benchmark model as it is now, with the objectives of promoting more discussions on this subject, and evolving the degree of information and exchange among power system engineers View full abstract»

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  • Improvement of the efficiency of 35 to 220 kV lines

    Publication Year: 1991 , Page(s): 226 - 231
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    It is good practice to limit the ratio of transmitted power to surge impedance loading (SIL, or natural capacity), S/Pn, to ⩽1, with the aim of reducing voltage drop and power losses. The use of flat phases and reduced phase spacings enable the ratio S/Pn to be confined to ⩽1, which considerably enhances the economic efficiency and quality of power transmission, enables the transmission distance to be increased and the operational lifetime of existing systems to be extended. Conductor bundling and ultimate reduction of phase spacings, down to distances determined by the requirements of reliable operation and lightning surges, allow an increase in the transmission capacity of 35 to 220 kV lines virtually in proportion to the number of subconductors per phase, i.e., by a factor of 3, 4 or more as compared to traditional lines. An increased transmission capacity of compact lines is attained with relatively small phase sizes View full abstract»

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  • Subsynchronous oscillation controller for Vindhyachal back-to-back HVDC link

    Publication Year: 1991 , Page(s): 290 - 294
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (212 KB)  

    The Vindhyachal back-to-back HVDC link interconnects the 400 kV AC networks of the Northern and Western power in India. The phenomena of subsynchronous oscillations due to adverse interaction between turbine generator torsional modes of oscillations and an HVDC system was discovered in 1977. To avoid damage to turbine-generator sets, it is therefore necessary to get a positive damping contribution for frequencies of interest from the HVDC system. The authors present results from such a study performed for the Vindhyachal back-to-back HVDC link on a simulator. It was found that the HVDC system could contribute negative damping to some of the torsional modes of oscillations of turbine generator units on both sides of the link. By modulating the firing angle of the converters with a signal generated from a wideband type of SSO controller, it was found that the oscillatory modes are well damped View full abstract»

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  • Some aspects of DC pollution tests

    Publication Year: 1991 , Page(s): 331 - 336
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (308 KB)  

    The authors discuss the importance of pollution tests on DC insulators and why they are difficult to perform. They then discuss the requirements for basic test sources including voltage drop and ripple and then discuss the requirements for the test objective and test equipment View full abstract»

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  • Network interaction tests of the Fenno-Skan HVDC link

    Publication Year: 1991 , Page(s): 285 - 289
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (316 KB)  

    The network interaction tests of the Fenno-Skan HVDC link between Finland and Sweden are described. The authors deal with the objectives, execution and analysis of the tests on the Finnish side. The purpose of the tests was to verify the compatibility of the link with the AC system. Besides this, the tests gave the possibility of verifying the quality of the system modelling. The large scale network interaction tests proved to be very valuable. A lot of experimental information of AC/DC interaction was gained. The link operated in the predicted and specified way. Based on the test results the modelling of hydroturbine governors was improved View full abstract»

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  • Power flow control by use of controllable components

    Publication Year: 1991 , Page(s): 398 - 400
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (156 KB)  

    The authors briefly discuss the virtues of controlling the power flow in an electric power system. A method to compute the control action needed for a required change in the output variables, i.e. the power flows on the predefined lines, is described. This method is illustrated on model systems for different purposes View full abstract»

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  • `Brownout' voltage stability-system measurement and simulation

    Publication Year: 1991 , Page(s): 307 - 312
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (340 KB)  

    The authors discuss the post fault voltage stability of utility systems and how this can be critically dependent upon the dynamics and characteristics of the load supplied. Specific reference is made to disturbance recorder outputs obtained following faults and during subsequent unique system wide load switching tests undertaken to identify the magnitude and duration of load dynamics following large scale disturbances. Example schemes are presented which stabilise the utility system following faults, utilising alternative compensation schemes. Conclusions are drawn as to the general applicability of the load characteristics and resulting effects with respect to other utilities on an international basis View full abstract»

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  • A comparison of HVDC transient simulation algorithms

    Publication Year: 1991 , Page(s): 368 - 373
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (292 KB)  

    By setting up an identical test system, the authors have shown that the two main algorithms used for the simulation of AC/DC disturbances, namely TCS (transient converter simulation) and EMTDC, can be made to agree in their prediction of the dynamic responses. The TCS algorithm, though reputed to be less efficient, uses fewer approximations and provides automatic selection of optimal integration steps. As a result the TCS responses are very consistent. With careful selection of the integration step the EMTDC program can produce practically the same responses as the state variable technique for reasonably symmetrical conditions. However some deterioration occurs with highly asymmetrical disturbances. This has been traced to the phase advance prediction, required by the subsystem concept, thus the EMTDC algorithm provides a very efficient solution at the expense of some accuracy. It can be concluded that both the EMTDC and TCS algorithms can be used with confidence to simulate the transient response of AC/DC convertors View full abstract»

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  • HVMDC: a new concept to feed small loads

    Publication Year: 1991 , Page(s): 120 - 125
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (304 KB)  

    Feeding small loads from HVDC transmission lines is a problem that has been investigated by many authors. The high voltage modulated direct current transmission (HVMDC) is a new concept to feed small loads which uses basically the same equipment involved on the conventional HVDC transmission. In this scheme, the DC current is used for transmitting large blocks of power to distant parts while a controlled superposed AC ripple is used to supply small loads close to the generating station. These small loads mat be located not very far from the rectifier's station due to the usual AC transmission long distance problems which depend upon the AC voltage, frequency and tranmission line characteristics. The authors present a theoretical steady-state analysis of such a HVMDC system and a preliminary HVMDC simulator study showing the feasibility of the proposed method, decreasing its advantages and problems View full abstract»

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  • The single European energy market: the electricity supply sector

    Publication Year: 1991 , Page(s): 60 - 62
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (152 KB)  

    The completion of the internal market in the Community by the end of 1992 has become a key objective and the focal point of the revival of the European Community. Within this overall objective, the development of the single European energy market, the internal energy Market, is a major element. Here, the author has attempted to give the background to the development of the internal energy market. It has not been possible to illustrate all of the many areas of impact on the electricity sector, but he has attempted to indicate the importance of the task and the magnitude of the challenges View full abstract»

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