Now showing 1 - 10 of 21
  • Publication
    Varying penetration ratios of wind turbine technologies for voltage and frequency stability
    This paper examines the ability of a power system to accommodate wind generation with varying ratios of doubly fed induction generator and fixed speed induction generator turbines from both static and dynamic aspects. By controlling the ratio between the two types of turbines, voltage stability is maintained for steady-state conditions for a large range of varying wind speeds. Using the ratio determined from the static analysis, the dynamic analysis explores the voltage and frequency characteristics of the system under contingency conditions. An initial analysis was carried out on the IEEE 30 bus test system. The results of this analysis are presented in this paper and detail how by varying the ratio of the turbine types the frequency stability and voltage stability can be improved.
    Scopus© Citations 38  1447
  • Publication
    Effect of generator flow control strategies on the long term dynamics of a model for power systems
    Cascading component failure can cause system-wide blackouts in power systems. Complex system analysis of the long term dynamics suggests that power transmission systems operate near a critical point. Here the effect of generator operation in a model for power systems is investigated. Two opposing methods of dispatching generators are compared. These two methods are to minimize and maximize the line flows with respect to their limits across the system. These methods are also compared to an economic dispatch. It is shown that the generator dispatch method used affects the frequency distributions and other statistics of blackouts. Dispatching using the maximization method causes a reduction in the frequencies of all blackouts as measured by the amount of load shed. This reduction is concurrent with an increase in the investment in the transmission system. These observations suggest that economic dispatch, while attempting to increase reliability, actually decreases the robustness of the system.
      552Scopus© Citations 1
  • Publication
    Optimal distributed generation plant mix with novel loss adjustment factors
    The distributed generation (DG) plant mix connected to any network section has a considerable impact on the total amount of DG energy exported and on the amount of losses incurred on the network. A new method for the calculation of loss adjustment factors (LAFs) for DG is presented, which determines the LAFs on a site specific and energy resource specific basis. A mixed integer linear program is formulated to optimally utilise the available energy resource on a distribution network section. The objective function incorporates the novel LAFs along with individual generation load factors, facilitating the determination of the optimal DG plant mix on a network section. Results are presented for a sample section of network illustrating the implementation of the optimal DG plant mix methodology for two representative energy resource portfolios.
      760Scopus© Citations 44
  • Publication
    Effect of short-term risk-aversive dispatch on a complex system model for power systems
    In the analysis of time series of blackouts a power law dependency of blackout size with respect to frequency has been observed. It has been hypothesized that this behaviour is the result of the power system operating near critical points. Models have been created in order to analyze this type of behaviour in power systems. In this paper the effect of conservative versus nonconservative generation dispatch is studied using one such model. Conservative dispatches are ones that are performed in order to minimize stress on the system and therefore attempt to minimize possible outages and blackouts. This dispatch is compared with a non-conservative dispatch that attempts to maximize the stress and therefore increase the immediate risk of outages and blackouts. It is found that the non-conservative dispatch although attempting to maximize the immediate risk reduces the frequency of blackouts of all sizes over the conservative dispatch in the long term.
      669Scopus© Citations 6
  • Publication
    A steady-state voltage stability analysis of power systems with high penetrations of wind
    As wind generation begins to contribute significantly to power systems, the need arises to assess the impact of this new source of variable generation on the stability of the system. This work provides a detailed methodology to assess the impact of wind generation on the voltage stability of a power system. It will also demonstrate the value of using time-series AC power flow analysis techniques in assessing the behavior of a power system. Traditional methods are insufficient in describing the nature of wind for steady-state analyses and as such a new methodology is presented to address this issue. Using this methodology, this paper will show how the voltage stability margin of the power system can be increased through the proper implementation of voltage control strategies in wind turbines.
    Scopus© Citations 247  4109
  • Publication
    Current methods to calculate capacity credit of wind power, IEA collaboration
    Power systems must have enough generation to meet demand at each moment of the day. In addition, they must also have enough reserve to deal with unexpected contingencies. The increase in the penetration of wind generation in recent years has led to a number of challenges in the calculations required to facilitate wind generation while maintaining the existing level of security of supply. A key calculation in this process is the capacity credit or value of wind generation. Capacity credit/value of wind generation can be broadly defined as the amount of firm conventional generation capacity that can be replaced with wind generation capacity, while maintaining the existing levels of security of supply. This topic has been the subject of much study and debate in recent times. The aim of this paper is to give an overview of the state of the art in this area, in particular with regard to the work of IEA WIND Task 25 and the work detailed in its state of the art report on the design and operation of power systems with large amounts of wind power.
    Scopus© Citations 58  2188
  • Publication
    Capacity value of wind power: summary
    The capacity value of a generator is the contribution that a given generator makes to generation system adequacy. Due to the variable and stochastic nature of wind, the modeling of wind generation in the same manner as conventional generation for capacity value calculation is inappropriate. In this paper a short summary of the issue is given. This summary is largely based on IEA task 25 activities and the output of an IEEE task force. A preferred method for calculating capacity value along with approximate methods for the calculation are also described with their limitations outlined.
      429
  • Publication
    Impact of distributed generation capacity on losses
    The introduction of distributed generation (DG) onto distribution networks has a significant effect on losses. This effect cannot be characterised as detrimental or beneficial but is dependent on the allocation of DG on each distribution network section. Here the impact of DG on losses has been modelled, facilitating a unique approach to the allocation of DG. This approach has been implemented and tested on sample sections of distribution network and results are presented showing the optimal allocation of DG which improves the efficiency of energy delivery on the distribution network. The temporal variations of load and generation are simulated, illustrating that the allocation improves the efficiency throughout a year. The effect of different plant mixes is also simulated showing that the efficiency of energy delivery is dependent on the load factor and operating characteristic of the plant.
    Scopus© Citations 11  637
  • Publication
    VSC-HVDC link to support voltage and frequency fluctuations for variable speed wind turbines for grid connection
    (Institute of Electrical and Electronics Engineers, 2012-10) ; ;
    This paper presents the use of induction generator turbine machines with simplified frequency control as a direct drive solution for wind energy conversion. An offshore wind farm system is proposed utilising a VSC-HVDC connection. The wind farm will contain variable speed wind turbines driving Squirrel Cage Induction Generators (SCIG). The study will look at the electrical performance of the generators with real wind data and the design control implications with a VSC-HVDC link. The performance of the system is verified by computer simulation using the Dymola/Modelica software platform with the ObjectStab power systems analysis toolbox. This paper presents the design of independently developed optimised power system models for variable speed wind turbine machines with simplified pitch angle and frequency control with a VSC-HVDC link for grid interconnection.
    Scopus© Citations 11  1493
  • Publication
    Capacity value of wind power, calculation, and data requirements : the Irish power system case
    The capacity value of wind power indicates the extent to which wind power contributes to the generation system adequacy of a power system. The related data requirements may be subject to difficulties due to the temporal variability and spatial distribution of wind power in connection with the limited databases currently available. This paper presents a methodology to identify the minimal amount of data required for reliable studies. Based on wind power data of 74 stations in Ireland, covering up to ten years, the effects of different numbers of stations and different time periods of data on the capacity value are analyzed. The calculations are performed by means of a fast calculation code. The results show that at least four to five years of data in an hourly resolution are necessary for reliable studies and that 40 to 50 evenly distributed stations give an acceptable representation of the total wind power generation in Ireland.
    Scopus© Citations 99  1420