Iet Renewable Power Generation
About: Iet Renewable Power Generation is an academic journal. The journal publishes majorly in the area(s): Wind power & Electric power system. It has an ISSN identifier of 1752-1416. It is also open access. Over the lifetime, 2235 publication(s) have been published receiving 49393 citation(s).
Topics: Wind power, Electric power system, Photovoltaic system, AC power, Maximum power point tracking
Abstract: This paper provides an overview of grid code technical requirements regarding the connection of large wind farms to the electric power systems. The grid codes examined are generally compiled by transmission system operators (TSOs) of countries or regions with high wind penetration and therefore incorporate the accumulated experience after several years of system operation at significant wind penetration levels. The paper focuses on the most important technical requirements for wind farms, included in most grid codes, such as active and reactive power regulation, voltage and frequency operating limits and wind farm behaviour during grid disturbances. The paper also includes a review of modern wind turbine technologies, regarding their capability of satisfying the requirements set by the codes, demonstrating that recent developments in wind turbine technology provide wind farms with stability and regulation capabilities directly comparable to those of conventional generating plants.
Abstract: 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.
Abstract: 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
Abstract: This study presents a smart energy management system (SEMS) to optimise the operation of the microgrid. The SEMS consists of power forecasting module, energy storage system (ESS) management module and optimisation module. The characteristic of the photovoltaics (PV) output in different weather conditions has been studied and then a 1-day-ahead power forecasting module is presented. As energy storage needs to be optimised across multiple-time steps, considering the influence of energy price structures, their economics are particularly complex. Therefore the ESS module is applied to determine the optimal operation strategies. Accordingly, multiple-time set points of the storage device, and economic performance of ESS are also evaluated. Smart management of ESS, economic load dispatch and operation optimisation of distributed generation (DG) are simplified into a single-object optimisation problem in the SEMS. Finally, a matrix real-coded genetic algorithm (MRC-GA) optimisation module is described to achieve a practical method for load management, including three different operation policies and produces diagrams of the distributed generators and ESS.
Abstract: We have investigated the reliability of more than 6000 modern onshore wind turbines and their subassemblies in Denmark and Germany over 11 years and particularly changes in reliability of generators, gearboxes and converters in a subset of 650 turbines in Schleswig Holstein, Germany. We first start by considering the average failure rate of turbine populations and then the average failure rates of wind turbine subassemblies. This analysis yields some surprising results about which subassemblies are the most unreliable. Then we proceed to consider the failure intensity function variation with time for wind turbines in one of these populations, using the Power Law Process, of three subassemblies; generator, gearbox and converter. This analysis shows that wind turbine gearboxes seem to be achieving reliabilities similar to gearboxes outside the wind industry. However, wind turbine generators and converters are both achieving reliabilities considerably below that of other industries but the reliability of these subassemblies improves with time. The paper also considers different wind turbine concepts. Then we conclude by proposing that offshore wind turbines should be subject to more rigorous reliability improvement measures, such as more thorough subassembly testing, to eliminate early failures. The early focus should be on converters and generators.
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