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Renewable Power Generation, IET

Issue 1 • Date March 2007

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Displaying Results 1 - 11 of 11
  • Editorial

    Page(s): 1
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (41 KB)  

    First Page of the Article
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  • Frequency support from doubly fed induction generator wind turbines

    Page(s): 3 - 9
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    An assessment on the capability of a doubly fed induction generator (DFIG) wind turbine for frequency regulation is presented. Detailed aerodynamic, structural and electrical dynamic models were used in this study. A control loop acting on the frequency deviation was added to the inertia contributing loop in order to enhance the inertia support from the DFIG wind turbine. The possibility of de-loading a wind turbine to provide primary and secondary frequency response was discussed. A frequency droop controller was examined where the droop is operating on the electronic torque set point below its maximum speed and is operating on the pitch demand at maximum speed. It is also shown that by reducing the generator torque set point the DFIG wind turbine can provide high frequency response View full abstract»

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  • Virtual power plant and system integration of distributed energy resources

    Page(s): 10 - 16
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (454 KB)  

    A concept is presented along with the overarching structure of the virtual power plant (VPP), the primary vehicle for delivering cost efficient integration of distributed energy resources (DER) into the existing power systems. The growing pressure, primarily driven by environmental concerns, for generating more electricity from renewables and improving energy efficiency have promoted the application of DER into electricity systems. So far, DER have been used to displace energy from conventional generating plants but not to displace their capacity as they are not visible to system operators. If this continues, this will lead to problematic over-capacity issues and under-utilisation of the assets, reduce overall system efficiency and eventually increase the electricity cost that needs to be paid by society. The concept of VPP was developed to enhance the visibility and control of DER to system operators and other market actors by providing an appropriate interface between these system components. The technical and commercial functionality facilitated through the VPP are described and concludes with case studies demonstrating the benefit of aggregation (VPP concept) and the use of the optimal power flow algorithm to characterise VPP View full abstract»

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  • Reaction force control of a linear electrical generator for direct drive wave energy conversion

    Page(s): 17 - 24
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (483 KB)  

    Direct drive wave energy converters have been proposed in view of the disadvantage of mechanical complexity and low conversion efficiencies in conventional wave energy converters. By directly coupling a linear generator to a reciprocating wave energy device, it is suggested that direct drive power take-off could be a viable alternative to hydraulic- and pneumatic-based systems. To further realise the benefits of a direct drive system, a control scheme based on reaction force control to maximise energy extraction is presented. It focuses predominantly on the theoretical analysis of the linear generator reaction force. The modelling, simulation and control of direct drive wave energy conversion are systematically investigated by computer-aided analysis via Matlab/Simulink View full abstract»

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  • Robust planning methodology for integration of stochastic generators in distribution grids

    Page(s): 25 - 32
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (722 KB)  

    The number of distributed generation (DG) units being connected at the lowand medium-voltage level is evermore increasing. Because of the mostly non-dispatchable generation profile of small-scale renewable power sources, grid performance can be ameliorated as well as deteriorated. A traditional mathematical optimisation of techno-economic objectives is elaborated upon. A conservative approach can, however, easily underestimate performance deviations due to the stochastic output of DG. A robust planning methodology is formulated, based on accuracy improving Monte Carlo simulations nested in an evolutionary algorithm. Multiple objectives are pursued to assess proper trade-offs regarding the technical and economical aspects View full abstract»

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  • Impact of widespread photovoltaics generation on distribution systems

    Page(s): 33 - 40
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (649 KB)  

    Prompted by the need for clean energy sources, increasing numbers of photovoltaic (PV) generators are being connected to electricity distribution systems around the world. There is thus a growing imperative to understand and quantify the technical impact that high penetrations of such generators may have on the operation and performance of electricity distribution systems. Detailed simulations of a very high penetration of PV within a typical UK urban distribution network (11 kV, 400 V and 230 V) are reported. The study performed unbalanced three-phase load-flow analysis on an entire feeder within a time-domain simulation framework using load and generation data at 1 minute intervals. The results indicate that even at very high penetrations of PV, network voltage rises are small and unlikely to cause problems. Effects on network power flows and losses are also quantified and discussed View full abstract»

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  • Reducing unnecessary disconnection of renewable generation from the power system

    Page(s): 41 - 48
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (146 KB)  

    Future power systems with large proportions of embedded generation could be severely affected if several loss of mains (LOM) protection systems maloperate in response to a non-islanding condition, potentially leading to generation shortfall and stability problems. Although many papers discuss methods of sensitively detecting islanded conditions (a short bibliographical survey is included), almost no papers in the literature address the problems associated with the stability of such protection methods during and after perturbations on the network to which they should not react. The aim is to highlight the shortcomings in existing power system protection practices relating to islanding detection with a view to identifying necessary areas of improvement to facilitate the ongoing proliferation of renewable sources in active distribution networks. Existing LOM techniques are described and stability-related shortcomings are demonstrated using the results of rigorous laboratory testing of several commercially available relays. The testing scenarios are developed using a UK Generic Distribution System repository, a public domain database representing typical distribution system architectures. Recommendations relating to the setting of existing LOM protection devices are provided, along with an overview of research and development activities relating to improvements in anti-islanding protection, including a discussion of both technical and economical viability View full abstract»

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  • Analysis of the combined use of wind and pumped storage systems in autonomous Greek islands

    Page(s): 49 - 60
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (543 KB)  

    In autonomous islands, the wind penetration is restricted due to technical reasons related with the safe operation of the electrical systems. The combined use of wind power with pumped storage (WPS) systems is considered as a means to exploit the abundant wind potential, increase the wind installed capacity and substitute conventional peak supply. An approach for the simulation of the autonomous electrical systems is proposed and applied in three islands. The simulation is based on the non-dynamic analysis of the electrical system, in order to calculate the energy contribution of the different power units. The aim is to analyse the prospects of WPS systems to decrease the electrical system's cost. The results show that the integration of WPS in autonomous islands may decrease the system's electricity production cost View full abstract»

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  • Calculation of economic transmission connection capacity for wind power generation

    Page(s): 61 - 69
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (421 KB)  

    Applications for the connection of large-scale wind power generation to transmission networks are presenting new issues both for transmission system planners and generation developers. One of the major problems faced is the assessment of transmission system capacity requirements for the export of power from areas with high penetration of variable and intermittent sources of generation such as wind power. A method for evaluating the required transmission connection capacity from an area dominated by wind generation to the main interconnected system is presented, based on historical time series data for both wind power generation output and the demand in the group. The operational implications for the transmission system and generation owners are evaluated using a cost-benefit approach. The method is demonstrated for a number of network situations. Conclusions are drawn about the value of the method and, more generally, about the trade-off between investment in transmission capacity and curtailment of wind generation under favourable wind conditions View full abstract»

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  • Development of a dynamic control communication system for hybrid power systems

    Page(s): 70 - 80
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (348 KB)  

    Hybrid power systems are the most attractive option for the electrification of remote locations. There are problems however that keep them from being widely implemented. These include high cost because of system complexity, site-specific design requirements and the lack of available control system flexibility. The solution to these problems is the creation of an appropriate and adaptable supervisory controller. Such a concept includes open standards, automatic component identification and an adaptable control algorithm. It assumes (1) hybrid power system components with communication ports allowing communication with a supervisory controller, (2) a central supervisory controller and (3) a communication network between each component in the system. A Universal Plug and Play specification is used to carry out the necessary functions of automatic component identification and inter-component communication. An experimental system (hardware and software) was constructed to prove the concept and to prepare a foundation for further development in the intelligent adaptable supervisory controller. The hardware involved two personal computers at its core: one containing the supervisory control and identification software and the other containing models of various system components. Tests were conducted that confirm the capability of this concept to use in hybrid power system View full abstract»

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  • Stability improvement of induction generator-based wind turbine systems

    Page(s): 81 - 93
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (518 KB)  

    The stability improvement of induction-generator-based wind turbine systems under power system fault conditions has been studied. Two types of generators are considered, namely rotor short-circuited induction generators and dynamic slip-controlled wound rotor induction generators. The factors affecting the stability are analysed. The characteristics of the induction-generator-based wind turbines are described, and possible methods of improving stability of the wind generators are discussed. The system modelling is presented, and then the discussed methods of improving stability are investigated. Simulation results have been presented and the effectiveness of the stability improvement methods has been discussed View full abstract»

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Aims & Scope

IET Renewable Power Generation brings together the topics of renewable energy technology, power generation and systems integration.

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