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Generation, Transmission & Distribution, IET

Issue 5 • Date May 2010

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Displaying Results 1 - 9 of 9
  • Probabilistic analysis for optimal power flow under uncertainty

    Publication Year: 2010 , Page(s): 553 - 561
    Cited by:  Papers (13)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (253 KB)  

    This study presents a probabilistic analysis to consider the impact of uncertain system parameters on optimal power flow (OPF). A general OPF under uncertainty is formulated as a chance-constrained programming model and its stochastic features are investigated. The impact of the uncertain variables is addressed by the probabilistic analysis with the method of Monte-Carlo simulation (MCS) combined with a deterministic optimisation. In this way, relations between the optimality and reliability in power systems under uncertainty can be achieved. The information derived from the statistical results can be applied in the system risk assessment and operation performance evaluation, which is helpful for making decisions in power system optimal dispatch under uncertainty. Case studies of a 5-bus system and the IEEE 30-bus system are presented to illustrate the probabilistic analysis. View full abstract»

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  • Adaptive voltage droop scheme for voltage source converters in an islanded multibus microgrid

    Publication Year: 2010 , Page(s): 562 - 578
    Cited by:  Papers (11)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1355 KB)  

    In this study, a novel voltage droop scheme for the parallel operation of voltage source converters (VSCs) in an islanded multibus microgrid is proposed. In this scheme, the voltage droop coefficient is defined as a function of respective VSC active and reactive power outputs. Thus, each VSCs voltage reference is adaptively drooped as a non-linear function of its active and reactive power outputs. This approach leads to reduction in the reactive power sharing dependence on real power control and system parameters such as mismatched connecting and line impedances. A multiobjective index is introduced for evaluating the scheme performance. The index is used as an objective function in an optimisation problem that is employed to obtain optimal parameters of the scheme. The detailed analysis shows that this scheme has a superior behaviour compared to the conventional voltage droop method, in view of the reactive power sharing and loads voltage control under all loading conditions. Simulation and experimental results show the good performance of the method for three paralleled VSCs in a multibus microgrid system. View full abstract»

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  • Optimal controller design of a doubly-fed induction generator wind turbine system for small signal stability enhancement

    Publication Year: 2010 , Page(s): 579 - 597
    Cited by:  Papers (21)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1054 KB)  

    Multi-objective optimal controller design of a doubly-fed induction generator (DFIG) wind turbine system using differential evolution (DE) is presented. A detailed mathematical model of DFIG wind turbine with a closed-loop vector control system is developed. Based on this, objective functions addressing the steady-state stability and dynamic performance at different operating conditions are implemented to optimise the controller parameters of both the rotor and grid-side converters. A superior ??-constraint method and method of adaptive penalties are applied to handle the multi-objective problem and the constraint with DE, respectively. Eigenvalue analysis and time-domain simulations are performed on a single machine infinite bus system as well as a nine-bus multi-machine system with two DFIG wind turbines to illustrate the control performance of the DFIG wind turbine with the optimised controller parameters. The electric energy productions of the studied DFIG wind turbine system with and without optimised controller parameters under turbulent wind speed are also demonstrated. View full abstract»

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  • Evaluating maximum wind energy exploitation in active distribution networks

    Publication Year: 2010 , Page(s): 598 - 608
    Cited by:  Papers (30)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (361 KB)  

    The increased spreading of distributed and renewable generation requires moving towards active management of distribution networks. In order to evaluate maximum wind energy exploitation in active distribution networks, a method based on a multi-period optimal power flow analysis is proposed. Active network management schemes such as coordinated voltage control, energy curtailment and power factor control are integrated in the method in order to investigate their impacts on the maximisation of wind energy exploitation. Some case studies, using real data from a Danish distribution system, confirmed the effectiveness of the proposed method in evaluating the optimal applications of active management schemes to increase wind energy harvesting without costly network reinforcement for the connection of wind generation. View full abstract»

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  • Generation re-dispatch algorithm against voltage collapse in Jeju island system with a frequency control by high-voltage direct current

    Publication Year: 2010 , Page(s): 609 - 619
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (695 KB)  

    A new algorithm for the determination of adequate generation re-dispatch as a protective measure against voltage instability is presented in this study. The study applies the method to the Jeju island system in Korea with a frequency control by the current sourced converter (CSC) high-voltage direct current (HVDC) system, which regulates the local system frequency by the active power injection from the mainland system. In order to transfer the active power using the CSC HVDC system, reactive power consumption is essential, and the frequency control of the HVDC is very fast. Therefore voltage instability may occur if the dynamic reactive support is not enough in the local power system at severe contingencies such as generator's outages. The authors suggest generation against voltage curves (g-V curves), constructed by generation continuation power flow, and propose the procedure to determine voltage stability limit of active power generation at each generator using g-V curves. An illustrative example of the proposed algorithm is shown as applied to the Jeju island system. View full abstract»

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  • Wide-area phasor power oscillation damping controller: A new approach to handling time-varying signal latency

    Publication Year: 2010 , Page(s): 620 - 630
    Cited by:  Papers (8)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1542 KB)  

    Using the present technology, latency associated with remote feedback signals can be determined from the time stamp information at both the phasor measurement unit (PMU) location and the control centre. This study illustrates how this latency could be accounted for in the implementation of a wide-area phasor power oscillation damping controller (phasor POD). The basic idea is to adjust the position of the rotating reference frame - used for phasor extraction - to account for the extra phase shift introduced because of latency. The oscillatory component of the original PMU measurement is retrieved out of the delayed signal received at the control centre. Thus, continuous compensation is achieved without requiring any Pade approximation and/or gain scheduling, unlike the techniques reported in the literature. With the proposed modification, a phasor POD is shown to continuously adapt to the actual latency and maintain the desired dynamic performance over a range of different operating conditions. View full abstract»

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  • Aspects to take into account in the application of mechanical calculation to high-temperature low-sag conductors

    Publication Year: 2010 , Page(s): 631 - 640
    Cited by:  Papers (6)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (234 KB)  

    Reconductoring with high-temperature low-sag (HTLS) conductors is an alternative to the traditional uprating methods. An increase in the obtained rating depends on the mechanical and thermal behaviours of the conductor. The HTLS conductors are presented and mechanical calculation methods are analysed taking into account the special characteristics of these conductors. The widely used graphical method and the recently developed STOC method have been analysed. View full abstract»

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  • Probabilistic power flow with correlated wind sources

    Publication Year: 2010 , Page(s): 641 - 651
    Cited by:  Papers (35)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (306 KB)  

    A probabilistic power flow model that takes into account spatially correlated power sources and loads is proposed. It is particularly appropriate to assess the impact of intermittent generators such as wind power ones on a power network. The proposed model is solved using an extended point estimate method that accounts for dependencies among the input random variables (i.e. loads and power sources). The proposed probabilistic power flow model is illustrated through 24-bus and 118-bus case studies. Finally, conclusions are duly drawn. View full abstract»

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  • Speed-up the computing efficiency of power system simulator for engineering-based power system transient stability simulations

    Publication Year: 2010 , Page(s): 652 - 661
    Cited by:  Papers (14)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (631 KB)  

    Power system simulator for engineering (PSS/E) has gained great success in power energy industry for its powerful simulation and analysis functions. Along with market deregulation, power system planning and stability analysis warrants more effective and faster techniques owing to the ever-expanding large-scale interconnection of power networks. Running large-scale system multiple case studies on PSS/E can be computationally very expensive and in some cases, simplifications have to be made in order to obtain some results. PSS/E dynamic simulations are accelerated with EnFuzion-based distributed computing method in this study. This approach is proved to be effective by testing with 39-bus New England power system under `N-1`, `N-2` and `N-1-1` contingencies analysis, and re-dispatch after disturbance with optimal power flow. The results show that the simulation process can be speeded up dramatically and the total elapsed time can be reduced proportionally with the increase of computer nodes. View full abstract»

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IET Generation, Transmission & Distribution is intended as a forum for the publication and discussion of current practice and future developments in electric power generation, transmission and distribution.

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