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Generation, Transmission and Distribution, IEE Proceedings C

Issue 2 • Date March 1985

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Displaying Results 1 - 10 of 10
  • Integral cycle control of stand-alone generators

    Page(s): 57 - 66
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1273 KB)  

    Reducing the cost of small-scale stand-alone generators (up to 100kW), particularly in micro-hydro applications, is of increasing interest. Methods proposed recently include the use of electronic load governors to regulate the generated frequency, and the use of induction generators in place of the more conventional synchronous generator. The use of a load governor results in constant-flow operation of the turbine, and thus eliminates any hydraulic stability problems. Many load governors switch increments of load on a cycle-by-cycle basis. Voltage regulation of induction generators may similarly be achieved by switching steps of capacitance each cycle. This paper analyses the stability of such integral cycle methods for controlling both synchronous and induction generators. The results, along with actual system responses, illustrate the viability of these techniques provided the stability requirements discussed are met. View full abstract»

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  • Operating unbalance in long-distance transmission

    Page(s): 67 - 75
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1173 KB)  

    Unbalance in steady-state operation is of general concern in power transmission, but it can be especially emphasised when transmission is over long distances, owing to the increasing influence of line parameter asymmetries on operating conditions as transmission-line lengths increase. Specifically in the context of long-distance transmission, the paper first develops procedures for evaluating the dependence of operating unbalance on the precise sets of connections when conductor transpositions are made at discrete points along the length of a transmission line. These are included in detailed phase-variable models for transmission-line sections, and on them is based an overall form of Newton-Raphson solution. The methods are applied to a representative long-distance transmission interconnection operating at 220kV and having two separated points of conductor transposition. The inherent operating unbalance in the interconnection is evaluated for a range of power-transfer conditions, and the extent to which the unbalance can be lowered by discrete transposition is quantified. The interaction of load unbalance and transmission-line parameter asymmetry is investigated, and load distributions are identified which lead to the greatest increase and the greatest reduction in unbalance in transmission. For an optimal choice of conductor transposition from a total of 35 possible sets of connections involving the two transposition points, the paper then investigates the further lowering of operating unbalance which saturated-reactor forms of shunt compensation at selected locations can additionally offer. In total, the paper provides a comprehensive investigation of operating unbalance in long-distance transmission from which several conclusions are drawn. View full abstract»

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  • Induction from underground power circuits into parallel communication services

    Page(s): 76 - 81
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (619 KB)  

    The paper describes a powerful method for computing voltages induced into pilot/communication cables in the event of a sudden fault in a neighbouring underground power circuit. The model uses multiconductor travelling-wave theory and is able to compute transient as well as steady-state induction. Given results clarify the extent to which transient effects add to postfault steady-state induction. The various factors affecting the level of induction are investigated, leading to the proposal of a simple formula. This formula is accredited against the standard of the full model and appears to offer sound practical estimates. View full abstract»

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  • Statistical analysis of electric-arc-furnace parameter variations

    Page(s): 82 - 93
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1536 KB)  

    During scrap melting, electric-arc-furnace parameters such as voltage and current, real and reactive power, resistance and reactance etc. exhibit significant variations about longer term mean values. The parameters can be considered to be random variables. The statistical properties of the parameter variations have been evaluated in this paper using data recorded on two 65 MVA furnaces. It is shown that the random variations of a broad range of parameters can be considered to be weakly stationary, but that the variations generally do not follow a Gaussian probability distribution. A significant correlation was found between the resistance and reactance variations per phase. The measured data was used to develop a strategy whereby the mean and standard deviation of the random variations could be measured online, with good accuracy, using conventionally available data-acquisition equipment. It is shown that an improperly chosen sampling strategy can yield quite misleading results. View full abstract»

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  • Polymeric cables 25/44kV and above

    Save to Project icon | PDF file iconPDF (383 KB)  
    Freely Available from IEEE