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Generation, Transmission and Distribution, IEE Proceedings C

Issue 1 • Date Jan 1990

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Displaying Results 1 - 10 of 10
  • Statistical processing of chopped currents and overvoltages in two types of sulphur hexafluoride breaker technology

    Page(s): 63 - 68
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (540 KB)  

    Tests on breaking three-phase low inductive currents were carried out with two medium-voltage SF6 breakers using different breaking techniques; the puffer method and the rotating arc. The statistical interpretation of the chopped currents and overvoltages produced by the two types of equipment showed that the two technologies performed satisfactorily, that is without excessive stresses for the system in service (in particular no successive restrikes on breaking) and with acceptable overvoltages caused by chopping. The typical values of the chopped currents measured were less than 1 A for rotating arc, and 3 to 8 A for puffer type circuit breaker. The overvoltages generated by the rotating arc circuit breaker (typically 2 p.u.) remain perceptibly lower than those caused by the other circuit breaker (typically 3 p.u.), even when using the former equipment at a voltage higher than its rated voltage. The results obtained are in line with the theory and experimental results View full abstract»

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  • Experimental analysis of DC corona on unipolar transmission lines

    Page(s): 53 - 62
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (728 KB)  

    To analyse the features of the ionised field produced by an HVDC transmission line, the unipolar weak corona performance is carefully investigated. In addition, in view of the facility of design performed with laboratory models, some guidelines are given for the scaling of experimental data derived from small-electrode installations to full-scale systems View full abstract»

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  • Application of a power system stabiliser and a static VAr controller to a multimachine power system

    Page(s): 8 - 12
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    The damping of the electromechanical mode oscillation in a multimachine power system is improved by a power system stabiliser (PSS). To prevent the system voltage profile from being deteriorated by the PSS, a static VAr compensator (SVC) with a self-tuning feedback controller is also developed. The effectiveness of the proposed PSS and SVC is demonstrated by computer simulation of the dynamic responses of the system subject to a three-phase fault. It is observed that the combination of PSS and SVC is capable of increasing system damping without deteriorating system voltage profile View full abstract»

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  • Automatic meter-reading system by power line carrier communications

    Page(s): 25 - 31
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (556 KB)  

    The authors are developing the technology of total distribution automation for performing load control, line switch control and automatic meter-reading by using ripple control (outbound signal in medium voltage), current answer-back signal (inbound signal in medium voltage) and phase pulse signal (two-way communication signal in low voltage distribution line). The authors cover the waveform-detecting method which has been developed as the sending and receiving technology by phase pulse signal. They also show that, by application of the waveform detecting method, more than 99.9% of total communication performance is secured View full abstract»

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  • Novel decoupled power flow

    Page(s): 1 - 7
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (484 KB)  

    A novel decoupled power flow method is reported, based on a novel decoupling form, and is developed for the purpose of obtaining best convergence. It is therefore referred to as the best in the novel decoupling form. The proposed method converges well not only on normal r/x ratio systems, but also on systems with high r /x ratio lines; the difficulties in convergence of decoupled power flow methods caused by high r/x ratio lines are overcome by the method proposed. Numerical results are presented to demonstrate the efficiency of the proposed method View full abstract»

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  • Multiple objective optimal load flow: a new perspective

    Page(s): 13 - 18
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (476 KB)  

    In the past a great deal of work has been reported on optimal load flow (OLF). However, in most of the works only one aspect of the power system has been optimised. The OLF problem (optimal real and reactive power dispatch) has been attempted sequentially, rather than simultaneously. A new formulation of the OLF problem has been attempted to minimise both the cost of generation and transmission loss simultaneously through a multiple objective programming technique (priority goal programming technique) View full abstract»

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  • Minimisation of uncharacteristic harmonics in HVDC convertors through firing angle modulation

    Page(s): 45 - 52
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (640 KB)  

    A modulating signal (MS) applied to the control voltage has a profound effect on the DC and AC-side uncharacteristic harmonic currents. The presence of harmonic distortion in the AC-busbar voltage causes distortion on the DC-line current ripple. A method of harmonic minimisation based on approximate linear relationships between uncharacteristic harmonics and the MS was developed and implemented on a convertor model. A circuit to select, adjust and inject the MS into the control voltage connected to the output of the injection circuit inhibits the MS injection during transients. This control feature is important because it allows fast transient response of the control and does not contribute to oscillatory behaviour. A full set of analytical predictions and model tests using the injection circuit described for an MS of 50 Hz, 100 Hz and 150 Hz is presented View full abstract»

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  • Thermal generator scheduling algorithm based on heuristic-guided depth-first search

    Page(s): 33 - 43
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (832 KB)  

    The authors develop an algorithm which is suitable for implementation on computers by a logic programming language, PROLOG, for scheduling thermal generators to meet the daily rising system demand and spinning reserve requirement in the operation of power systems. The algorithm is based on the depth-first and heuristic search techniques in artificial intelligence, and an interpretation of the scheduling process as a tree searching problem. Heuristic rules are derived for overcoming the problem of combinatorial explosion in the search space of the scheduling process and for quickly determining the solution schedule having the lowest total excessive generation capacity between the total generation capacity and the combined system demand and spinning reserve. The ramp rate characteristics and crew constraints of generator units together with the system constraint of must-on units are incorporated in the algorithm. The application of the developed algorithm which is implemented by PROLOG to schedule ten thermal generators is presented View full abstract»

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  • Optimal network tearing using simulated annealing

    Page(s): 69 - 72
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (328 KB)  

    A new algorithm for optimal tearing of networks is presented. The algorithm is based on the simulated annealing principle and is able to divide a power system network model into a number of subnetworks in order to optimise the use of parallel computer systems for network analysis. Computational examples are given which illustrate the properties of the new algorithm. The results obtained are compared with those obtained by the iterative improvement method, and it is shown that the annealing algorithm finds significantly better solutions View full abstract»

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  • Digital high-speed calculation of the distorted signal fundamental component

    Page(s): 19 - 24
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (368 KB)  

    Calculation of current and voltage phasors in power system protection and control is based on correlation of the signals with sine/cosine (or similar) functions, assuming data windows which are constant and usually amount to one period of the fundamental frequency. However this method introduces large errors in transient states, which follow changes of the signal amplitude and/or phase. The transient state lasts as long as the window. The transient errors are eliminated, if the correlation procedure utilises variable data windows which increase until they reach the one full cycle of the fundamental frequency and then become constant. This enables a phasor to be calculated within 1/4 cycle after the input signal changed. The algorithm is very fast, quite accurate and computationally efficient View full abstract»

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