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The Growing Role of Technical Certification in Distributed Wind
The European distributed wind market, where power is produced using small or medium-scale turbines close to where it is consumed, is still at an early stage of development. While medium-scale manufacturers and developers in the UK and Italy have profited from incentives that have spurred growth, other countries are yet to match this level of activity. And, even in the relatively established markets, uncertainty over tariff levels and variations in the certification requirements for different sizes of turbine have not helped things.
By Miguel Hoyos Irisarri, Technical Director, Norvento, Spain
The UK has a feed-in tariff (FiT) system that auto-regulates itself, lowering payments as more capacity is brought on-line throughout the country. This system was introduced on the premise that initial growth would contribute to a proportional reduction in costs for the supply chain. Since the introduction of FiTs in 2010, the industry has managed to reduce the CAPEX costs of a standard project by approximately 11%. Tariffs, meanwhile, have reduced by 35% on average (based on RenewableUK data for the 15 to 500kW range).
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Modern, Wind-specific Technology Provides Optimised Performance, Remote Monitoring and Control
Rapid developments in electronics and control systems over the last 30 years have provided new opportunities for operation of wind turbines. Retrofitting older turbines with a modern control system provides the turbine owner with significant improvements in relation to remote monitoring, control and root cause analysis. Although retrofitting a control system is a technical challenge, the benefits are clear: improved turbine performance both in terms of availability and power production. This article describes the challenges and results of a customer project undertaken by KK Wind Solutions to develop and install retrofit solutions for a Bonus 1.3MW and a Vestas V47 turbine.
By René Balle, Chief Technology Officer, KK Wind Solutions, Denmark
At the beginning of 2014, KK Wind Solutions started a customer project with the aim of developing retrofit solutions for a Vestas V47 and a Bonus 1.3MW turbine. Eight months later, the two solutions, based on a modern, sixth-generation control system, were installed and commissioned at the site in the USA.
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AdBm Butendiek Noise Reduction Demonstration
AdBm Technologies, working with WPD and Ballast Nedam, demonstrated their new underwater noise abatement system during pile-driving operations in the construction of the Butendiek Offshore Wind Farm in the North Sea. The panel-based AdBm system was smoothly and quickly deployed and recovered four times. Acoustic testing was conducted at three locations ranging from 285 to 750 metres from where the monopile was being driven. Measurements were collected on 668 hammer strikes at a distance of 285 metres from the monopile. Attenuation of up to 36.8dB was realised across all hammer strikes at this location. At 750 metres from the monopile, 136 hammer strikes were analysed and the noise radiated from the pile-driving was attenuated to the level of ambient noise near the recording vessel, which ranged on average from 140 to 150dB at a reference pressure of 1 µPa. These results demonstrate that frequency-targeted reduction of underwater noise is possible and can be highly effective.
By Mark Wochner, CEO, AdBm Technologies, USA
Working out of Esbjerg in Denmark, Ballast Nedam began pile-driving operations for the Butendiek Offshore Wind Farm on 1 April 2014. Vessels involved in the project include the HLV ‘Svanen’ and the Multicat ‘Mena C’ of Rhu. The acoustic tests discussed here occurred on 11–12 July 2014 on pile BU-21.
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Investigating the Feasibility of Self-Buoyant Concepts
The gravity concept, originally implemented in the Oil & Gas sector, is based on utilising the dead weight of the foundation material (typically concrete) to generate the restoring forces required to resist the high lateral loads and overturning moments resulting from the service loads. However, the significant dead weight of the foundation usually results in costly transportation and installation operations, given the high charter rates of the required vessels, lifting cranes and infrastructures. Achieving the EU targets for the levelised cost of energy (LCOE) of offshore wind encourages development of alternative approaches with cost reduction potentials. Several gravity concepts have been proposed in recent years, to attain a self-buoyant gravity base foundation, and thereby minimise the need for costly marine operations. This article reports a parametric study that investigates the feasibility and cost-benefit of such concepts, in terms of performance, intermediate stability and their impact on the overall cost of foundations.
By Dr Azadeh Attari and Dr Paul Doherty, GDG, Ireland
Often pitched as an unconventional substructure, gravity base foundations (GBFs) are in fact one of the most common foundation types employed in the offshore wind industry to date (Figure 1). At the end of 2013, 12% of the total number of fully installed substructures in European waters were gravity bases.
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Performance Stability of Continuous Wave Lidars in High Motion, Offshore Environments for Wind Resource Assessments
Remote sensing on floating offshore platforms such as buoys, barges and ships provides a cost-effective alternative to expensive foundation-mounted offshore wind monitoring towers for wind resource assessment [1][2]. In addition, it is unlikely that foundation-mounted offshore meteorological masts will ever be viable in water depths of over 30 metres, whereas floating platforms can be deployed in more or less any water depth. This will become particularly relevant as floating wind turbines in deep offshore waters start to come on-line.
By Mark Pitter, Scientist and Offshore Applications Leader, and Alex Woodward, Head of Product Development, ZephIR Lidar, UK
Remote sensors mounted on floating platforms are often subjected to motion. Buoys typically exhibit both translational and rotational motions and these motions have the potential to adversely affect the measurement of the wind vector. In this article the effect of motion on remote sensor performance and in particular the ZephIR 300 Continuous Wave (CW) wind lidar will be described. In addition it will be demonstrated by theory, experimental results and field trials that these motions can be tolerated, or the measurement methodology adapted such that their effect on the accuracy and precision of the wind measurement can be negligible, a unique property of the CW architecture found in all ZephIR lidars.
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Cold Climate Issues for Wind Turbine Machinery
Wind turbines are installed worldwide, and therefore these systems need to operate in different climates and environmental conditions, from arctic cold to blistering desert heat. And, they need to work in these extreme conditions for 15 to 20 years without having major breakdowns. Design engineers need to take such climates into account in order to have a reliable and efficient product in all conditions. Currently, wind turbines are more frequently installed in so-called ‘cold climate’ or ‘low temperature climate’ locations where temperatures below -20°C are not that uncommon. Standard turbines are designed to operate in -10°C temperatures, and survive in -20°C conditions. However, recent weather data from places such as Inner Mongolia and Canada indicates that even -45°C and -50°C can occur in some locations. This article discusses the problems such extreme temperatures can cause and how climatic chamber testing can help designers produce turbines suitable for the conditions.
By Pieter Jan Jordaens, Business Development & Innovation manager, OWI-Lab, Belgium
As the market for low temperature turbines expands the importance of having reliable and efficient turbines in such locations becomes of vital interest. Many of these cold climate locations have profitable average wind speeds and free installation space, and the higher air density in cold weather makes this market attractive to investors, if the turbine manufacturers can guarantee high availability, reliability and efficiency.
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The Need for and Advantages of Advanced Ground Testing
This article seeks to demonstrate the comprehensive capabilities and benefits of wind turbine generator (WTG) system test benches that are integrated into a multi-physical hardware in the loop (HIL) environment. In 2012 and 2013 the Center for Wind Power Drives successfully proved the use of HIL for advanced ground testing with a test campaign on a 1MW test bench demonstrator. In addition, a new 4MW WTG system test bench was brought into operation in late 2014. With regard to type certification tests, ground testing has the potential to be a substitute for field prototype testing as a faster, more cost efficient and flexible alternative. Beyond this, ground testing can be used for validating new WTG designs and improving reliability. The HIL operating mode makes it possible to simulate the working environment of a WTG and to consider the influence of the WTG controller strategy on the mechanical and electrical loads of the drive-train.
By Dipl.-Ing. Stefan Franzen, Dipl.-Ing. Dennis Bosse, Dipl.-Ing. Dominik Radner, Prof. Dr.-Ing. Georg Jacobs and Dr.-Ing. Ralf Schelenz, Center for Wind Power Drives, RWTH Aachen University, Germany
Following an introduction that outlines the need for a full-size ground-testing capability, the main part of the article introduces the design of the Center for Wind Power Drives’ 4MW WTG system test bench and the implementation of the HIL environment. The article concludes by outlining the benefits of and future prospects for the system test benches and the HIL integration.
