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Generation, Transmission and Distribution, IEE Proceedings-

Issue 5 • Date Sep 2000

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Displaying Results 1 - 8 of 8
  • Application of Monte Carlo simulation to optimal maintenance scheduling in a parallel-redundant system

    Page(s): 274 - 278
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    A modified distribution function is created based on the assumption that the component useful life phase is associated with an exponential distribution and the wearout period is subject to a Weibull distribution (β>1). Using the modified distribution function, a Monte Carlo simulation approach is used to obtain the total failure frequency and optimum maintenance interval for a parallel-redundant system where each component can enter its wearout period. Two examples are used to illustrate the simulation procedure. The effect of the Weibull parameter β on the optimum maintenance interval for a parallel-redundant system is illustrated View full abstract»

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  • Dynamic model of discharge propagation on polluted surfaces under impulse voltages

    Page(s): 279 - 284
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (408 KB)  

    A predictive flashover dynamic model of polluted surfaces under impulse voltages, i.e. bi-exponential waves simulating lightning and switching impulse voltages, is presented. It uses an equivalent electrical network and an analytical discharge propagation criterion that has been established elsewhere. The model enables different characteristics of the discharge, such as the current and the electrical charge, to be computed and the discharge propagation velocity to be determined using an energetic balance. The influence of the thickness and the resistivity of the polluted layer on the discharge velocity are analysed. The obtained results are found to be in good accordance with those obtained experimentally using an electrolytic solution model View full abstract»

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  • Robust power system stabiliser

    Page(s): 285 - 291
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (488 KB)  

    Power system stabilisers (PSS) are usually implemented by feeding a speed signal through a supplementary loop that comprises a proper phase lead. The design parameters of this loop are load dependent. Thus, they have to be adjusted at each operating condition. A simple robust PSS is designed that can properly function over a wide range of operating conditions and extend the machine loadability. The lead compensator design is achieved by drawing the root loci for a finite number of extreme characteristic polynomials. Such polynomials are obtained, using the Kharitonov theorem, to reflect wide loading conditions on characteristic equation coefficients. For this purpose the explicit analytical forms for the coefficients of the system transfer functions are derived. Simulation results illustrate the effectiveness of the proposed stabiliser as it is applied to the original nonlinear differential equations describing system dynamics under wide loading conditions at lagging and leading power factors. View full abstract»

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  • Use of superconducting magnetic energy storage device in a power system to permit delayed tripping

    Page(s): 269 - 273
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (388 KB)  

    Use of a superconducting magnetic energy storage (SMES) device in an electric power system can extend the time margin required for clearing a fault without any loss of stability of the synchronous generators in the system. Necessary mathematical model and computer simulation results have been presented. A wider time margin would be beneficial in many ways, such as precluding unwanted line tripping following temporary earth fault or transient swings, deferring costly replacement of the existing relays and breakers by the faster ones, and making a fair decision on tripping, taking into consideration a large volume of on-line data, constraints and complicated policies likely to be encountered in operating a power system under deregulation or a competitive market environment View full abstract»

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  • Power system monitoring using Petri net embeddings

    Page(s): 299 - 303
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (436 KB)  

    A failure in a power transmission line causes a number of circuit breakers to activate in an effort to isolate the failure and prevent it from corrupting the rest of the power system. Based on information from these physically distributed protective devices, a central controller needs to quickly locate and identify the failure. The task becomes challenging due to the complexity of modern power transmission networks and due to the possibility of sensor failures or incorrect operation of protective devices. A solution to this problem is investigated using Petri net models. The authors' approach allows concurrent/incremental processing of the information that arrives at the controller and only requires simple calculations (linear checks) during execution time. Most reasoning is implicitly performed at design time, which gives their method an important edge for real-time monitoring. These same techniques can potentially handle multiple failures or perform hierarchical and/or distributed monitoring View full abstract»

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  • Application of radial basis function networks for solar-array modelling and maximum power-point prediction

    Page(s): 310 - 316
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (528 KB)  

    A neural network-based approach for solar array modelling is presented. The logic hidden unit of the proposed network consists of a set of nonlinear radial basis functions (RBFs) which are connected directly to the input vector. The links between hidden and output units are linear. The model can be trained using a random set of data collected from a real photovoltaic (PV) plant. The training procedures are fast and the accuracy of the trained models is comparable with that of the conventional model. The principle and training procedures of the RBF-network modelling when applied to emulate the I-V characteristics of PV arrays are discussed. Simulation results of the trained RBF networks for modelling a PV array and predicting the maximum power points of a real PV panel are presented View full abstract»

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  • Hybrid optical current transformer with optical and power-line energisation

    Page(s): 304 - 309
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (576 KB)  

    The hybrid optical current transformer (HOCT) has previously been proposed as a suitable device to replace a conventional open-terminal post-type current transformer. The HOCT is much smaller than the conventional device leading to lower manufacturing costs. There is also a degree of electrical insulation inherent as optical fibre is used for connections between the line-mounted HOCT and ground level instrumentation; this reduces installation costs. A performance specification for a HOCT is presented: a HOCT unit satisfying this specification could, in principle, be a suitable replacement for a conventional device for power system protection purposes without loss of system quality or reliability. A prototype HOCT has been designed and constructed; initial tests show that it meets the specified accuracy requirements over the full operating temperature range. As far as can be determined, this is the first alternative to conventional current transformers that has been shown to meet these stringent requirements View full abstract»

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