Your browser does not support JavaScript!
http://iet.metastore.ingenta.com
1887
banner image
image of Volume 2, Issue 2
Online ISSN 1752-1424 Print ISSN 1752-1416

IET Renewable Power Generation

Volume 2, Issue 2, June 2008

Volumes & issues:

Volume 2, Issue 2

June 2008

Show / Hide details

    • Introducing a coloured fluid stochastic Petri net-based methodology for reliability and performance evaluation of small isolated power systems including wind turbines
      • Author(s): Y.A. Katsigiannis ; P.S. Georgilakis ; G.J. Tsinarakis
      • Source: IET Renewable Power Generation, Volume 2, Issue 2, p. 75 –88
      • DOI:  10.1049/iet-rpg:20070012
      • Type: Article
      • + Show details - Hide details
      • p. 75 –88 (14)
        A new approach in reliability evaluation of small isolated hybrid power systems, which include wind turbines and conventional generators, based on fluid stochastic Petri net (PN) modelling is presented. A major novelty of the proposed methodology is that a selection of constant time intervals is adopted, instead of assuming continuous dynamics. The proposed analysis presents similar characteristics with simulation methods, with the additional advantages of graphical representation of system's components and attributes. Moreover, emphasis is given on the parameterisation of input data that describes operational and reliability characteristics of the system, so a global investigation of the examined system can be done. In order to import more precise data in the simulation process modelled by the PN, the concept of database arcs is introduced. The evaluation is based on the calculation of system's basic indices related to reliability estimation and energy production. The results obtained verify the flexibility and the capabilities of the proposed methodology.
        Add to favourites
        Export citations
      Initial study of using rechargeable batteries in wind power generation with variable speed induction generators
      • Author(s): T.C. Yang
      • Source: IET Renewable Power Generation, Volume 2, Issue 2, p. 89 –101
      • DOI:  10.1049/iet-rpg:20070008
      • Type: Article
      • + Show details - Hide details
      • p. 89 –101 (13)
        There is a possibility of having a small rechargeable battery bank consisting of one or two groups of batteries inside a wind turbine tower. This paper investigates such a possibility for wind turbines using double fed induction generators (DFIGs). Two schemes are proposed. The first scheme, BS1, uses rechargeable batteries as an energy source/sink for the control of generator rotor currents. The second scheme, BS2, in addition to the batteries under BS1, has another group of batteries to smooth wind turbine power output and to provide power balancing and emergency support to the grid. A case study is used to evaluate these two schemes. The study is based on the statistics of the wind speeds measured at Dunstaffnage, Scotland, and the manufacturer's data for the turbine generator. It shows that if the proposed BS2 scheme is adopted and some mild assumptions are used in simulation: (1) variation of the turbine power output to the grid is reduced – the variation of the output of a wind farm is within 13% of the combined ratings of all turbines in the farm; (2) less variation in power also means smoother currents and reduced I2R loss – for some cables in the wind farm plant this is a reduction of more than 53%; (3) requirements or ratings of some equipment can be reduced – the capacitor and filtering circuits for the DC bus are no longer required and the ratings of some transformers can be reduced; (4) some complicated control can be simplified – the control for the grid-side converter under the current ‘DFIG scheme’ is replaced by a simple battery charging/discharging algorithm; (5) the wind turbine plant will be more supportive to the grid; and from the grid point of view, the performance of the wind farms adopting the proposed BS2 scheme will be similar to and in certain aspects even better than that of power plants using fossil fuels; and (6) all the above will bring some economic benefits at the expense of some additional costs associated with using batteries. Some practical issues, including available space in a typical turbine tower, are also discussed. The simulation results presented, however, are limited to steady-state models. Further research will include the type of batteries to be used, more detailed dynamic studies and quantified analysis of economic benefits and costs.
        Add to favourites
        Export citations
      Evaluation of the voltage change factor kU for DG equipped with synchronous generators
      • Author(s): N.A. Kasmas  and  S.A. Papathanassiou
      • Source: IET Renewable Power Generation, Volume 2, Issue 2, p. 102 –112
      • DOI:  10.1049/iet-rpg:20070015
      • Type: Article
      • + Show details - Hide details
      • p. 102 –112 (11)
        An evaluation of the voltage disturbances caused by the synchronisation to the grid of distributed generation (DG) resources equipped with synchronous generators is presented. The synchronisation procedures and the resulting transients are first discussed. The effect of the synchronisation conditions (frequency, phase, voltage magnitude deviations) on the resulting fast voltage changes is then demonstrated through an extensive set of simulations. The investigation is extended to the effect of other parameters of the grid and the generator. Objective of the analysis is to shed some light on the selection of appropriate values for the voltage change factor kU, as per IEC 61400-21, which is used in practical situations to evaluate the fast voltage changes due to the connection of DG power stations.
        Add to favourites
        Export citations
      Analysis of injected apparent power and flicker in a distribution network after wind power plant connection
      • Author(s): A.P. de Moura ; A.A.F. de Moura ; A.A.F. de Moura
      • Source: IET Renewable Power Generation, Volume 2, Issue 2, p. 113 –122
      • DOI:  10.1049/iet-rpg:20070059
      • Type: Article
      • + Show details - Hide details
      • p. 113 –122 (10)
        The maximum apparent power that can be injected in a bus and the flicker emission can represent a significant limit in the total capacity of a wind farm when wind turbines are connected to a radial distribution system. Quantification of these values is important in determining the largest number of wind turbines that can be connected in a network. The calculation of maximum apparent power and flicker of residential and commercial radial distribution feeder with remotely connected wind turbines has been investigated using elaborated specific software denominated winds port program and data from two energy systems. The developed software can calculate the approximate injected maximum apparent power, for a wind farm, in one bus of the network and in two buses of the network, simultaneously, without the need of a load flow program. The various simulations results reveal that wind farm capacities, in each bus, can be limited firstly for flicker and later for bus injected power for a voltage variation value, and the calculation of approximate apparent powers allows a precise and fast adjustment of voltage variation. If a load flow program is used for the determination of the wind farm maximum apparent power in each bus of the distribution system, a lot of simulations with a lot of attempts must be necessary. Therefore the methodology used by the authors is advantageous.
        Add to favourites
        Export citations
      Overview of different wind generator systems and their comparisons
      • Author(s): H. Li  and  Z. Chen
      • Source: IET Renewable Power Generation, Volume 2, Issue 2, p. 123 –138
      • DOI:  10.1049/iet-rpg:20070044
      • Type: Article
      • + Show details - Hide details
      • p. 123 –138 (16)
        With rapid development of wind power technologies and significant growth of wind power capacity installed worldwide, various wind turbine concepts have been developed. The wind energy conversion system is demanded to be more cost-competitive, so that comparisons of different wind generator systems are necessary. An overview of different wind generator systems and their comparisons are presented. First, the contemporary wind turbines are classified with respect to both their control features and drive train types, and their strengths and weaknesses are described. The promising permanent magnet generator types are also investigated. Then, the quantitative comparison and market penetration of different wind generator systems are presented. Finally, the developing trends of wind generator systems and appropriate comparison criteria are discussed. It is shown that variable speed concepts with power electronics will continue to dominate and be very promising technologies for large wind farms. The future success of different wind turbine concepts may strongly depend on their ability of complying with both market expectations and the requirements of grid utility companies.
        Add to favourites
        Export citations

Most viewed content for this Journal

Article
content/journals/iet-rpg
Journal
5
Loading

Most cited content for this Journal

Print this page
This is a required field
Please enter a valid email address