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Generation, Transmission and Distribution, IEE Proceedings C

Issue 4 • Date Jul 1990

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Displaying Results 1 - 10 of 10
  • Frequency domain analysis of power system forced oscillations

    Page(s): 261 - 268
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (552 KB)  

    A frequency domain approach is used to analyse power system forced low frequency oscillations. The gain characteristics of a closed loop transfer function, which reflects the effect of disturbances on power angle oscillations, are shown to be crucial in identifying the frequency ranges in which amplified oscillatory disturbances can occur. It is shown that tuning power system stabilisers (PSS), based on eigenvalue analysis, lack the insight gained from the explicit evaluation of the gain response. The authors also propose a dynamic gain reduction scheme which decouples the negative damping effects while accentuating the stabilising effects of the PSS derivative feedback. It is shown that a considerable reduction in the tie-line mode oscillations can be achieved View full abstract»

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  • Study of super-bundle and low-reactance phasings on untransposed twin-circuit lines

    Page(s): 245 - 254
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (520 KB)  

    The authors compare the characteristic of low-reactance (LR) phasing, including a single-circuit operation, with that of a more popular super-bundle (SB) phasing of untransposed twin-circuit lines and also with that of a transposed twin-circuit line. Using results calculated by the EMTP and an analytical formula for the symmetrical components of phase currents, it is found that the zero and negative-sequence components of phase currents, the electric field strength, and the inducing current of steady-state electromagnetic induction to a telecommunication line are reduced by between 30% and 60% if the LR phasing is adopted in preference to the SB phasing. It is found that the analytical formula is satisfactorily accurate compared with the EMTP result and can explain the characteristics of various phasing arrangements View full abstract»

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  • Optimum operating policy for energy storage for an interconnected power system

    Page(s): 291 - 297
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (404 KB)  

    Economical operation of integrated power systems with energy storage has been attempted as a dynamic programming formulation (DPF). The dimensionality of the problem may be unacceptable especially when a large number of storage devices and interconnected power plants are used. The authors suggest another method, based on the generalised network programming formulation (GNP), to solve the problem with minimum computational requirements. The proposed method can be used to find the optimum energy interchange between multiple area systems over a period of 24 h. This method can represent the power losses between the generating units and the storage system, losses of the transmission network and the nonlinear production cost functions. The power system security is also incorporated in this method. For the sake of comparison, the problem is also solved by the DPF, and the results show that the proposed method is computationally efficient and is suitable for practical applications View full abstract»

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  • Estimation of parameters in transient stability output swings using autoregressive models

    Page(s): 315 - 320
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (420 KB)  

    The author presents a data processing technique for the analysis of output waveforms from transient stability programs. The method is an autoregressive process based on an extension of Prony's method. Using this approach an algorithm is proposed to determine the main parameters that identify a particular waveform. These parameters include the amplitude, frequency, damping constant and phase angle of each mode of oscillation in the swing curve. The algorithm incorporates these variables in the solution and there is no need for further numerical analysis. The effectiveness of the algorithm is verified by tests on both artificial waveforms and actual swing curves from a stability program. The computational complexity, necessary precautions, other applications and improvements are also presented View full abstract»

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  • Identification of coherent generators using energy function

    Page(s): 255 - 260
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (400 KB)  

    A new method of identifying coherent generators for multiple faults in a power system is presented. A tentative coherent group of generators is initially determined by evaluating the energy function at different approximate unstable equilibrium points of the system. The final coherent groups for individual faults are obtained by checking relative rotor angles in the faulted system. The method is fast and saves a great deal of computation time. The proposed method is tested on three power networks and the results obtained perfectly matched with those found from classical simulation studies View full abstract»

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  • Economic assessment of energy storage options in generation expansion planning

    Page(s): 298 - 306
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (548 KB)  

    An efficient method to assess the economic feasibility of introducing a storage capacity alongside a conventional generation system is presented. The operational cost saving of the optimally operated storage capacity with the conventional system is determined using a production simulation model. This is optimised so that a generation schedule for a power system with a storage facility will accurately reflect the time dependency of storage operation policies through the charging and discharging processes. The optimum capacity of a storage facility is chosen to minimise the total revenue requirements and to satisfy the system reliability constraint for each year in the plan View full abstract»

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  • New approach to the analysis of impulse voltage distribution in transformer windings

    Page(s): 283 - 290
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (444 KB)  

    A new calculation method for the analysis of transient voltage phenomena in HV power transformers is presented. Consideration is given to the electric, magnetic and current fields in the windings. An equivalent circuit is derived; this consists in the connection of two networks, one magnetic the other electric, whose components with their numerical values are deduced directly from the geometry of the transformer and from its electrical parameters. Application of the ensuing mathematical model to a real case of a 132 kV, 50000 kVA power transformer is discussed View full abstract»

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  • Probabilistic load flow by a multilinear simulation algorithm

    Page(s): 276 - 282
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (536 KB)  

    Load flow analysis is undoubtedly the most useful method of designing and operating power systems. The input data necessary for these studies are best described by random variables, considering the probabilistic nature of loads, generation and networks. The effects of uncertainties on the steady-state behaviour of power systems can be evaluated by a stochastic or probabilistic load flow (PLF) analysis. The authors present a new method for obtaining the PLF solution, by combining Monte Carlo simulation techniques and linearised power flow equations for different system load levels. The performance of the proposed algorithm is illustrated through the IEEE 14-busbar test system, and also through its application in part of the Brazilian network View full abstract»

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  • New approach to power line protection based upon the detection of fault induced high frequency signals

    Page(s): 307 - 313
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    The authors outline the salient features of a protection technique for transmission lines which utilises the high frequency components of fault generated noise. The approach is based on the nonunit type scheme, which makes use of a stack-tuner circuit connected to the coupling capacitor of a capacitor voltage transformer. The stack-tuner is tuned to a certain frequency bandwidth and is arranged to act as a high frequency switch. The signals derived from the stack-tuner are used to determine whether the fault is inside or outside the protected zone View full abstract»

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  • Self-tuning control scheme for stability enhancement of multimachine power systems

    Page(s): 269 - 275
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (432 KB)  

    A decentralised self-tuning control scheme for the stability enhancement of multimachine power systems is presented. The dynamic performance of each machine in the study multimachine system is described by a discrete-time model for the purpose of stabiliser design. Each stabiliser is designed using this discrete-time model and a performance index which enhances the damping characteristic of the overall multimachine system is defined. Nonlinear simulation tests show that the proposed self-tuning control scheme is suitable for the stability enhancement of two multimachine power systems, both for small and large disturbances and for different operating conditions. It is also demonstrated that the proposed self-tuning stabiliser can effectively co-operate with the conventional fixed parameter stabiliser, to improve the system stability View full abstract»

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