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- Category: Articles
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
- Category: Articles
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
- Category: Articles
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
- Category: Articles
A Tool to Avoid Aerodynamic Imbalance
The accurate synchronisation of rotor blades is an important requirement for the optimal operation of wind turbines in relation to both generation and loads. Because of the lack of appropriate measurement devices that allow easy and timesaving inspection, the problem has long been underestimated and neglected at the same time. However, with the development of new, highly efficient wind turbines with extremely long rotor blades, misalignment has become a greater problem due to the substantial surplus loads caused by aerodynamical imbalance. The subject shifted into the focus of manufacturers and operators and caught growing interest as it applies to all wind energy converters.
By J. Dietrich Mayer, Managing Director, windcomp, Germany
- Category: Articles
Offshore Wind Turbines to Provide Combined Electricity and Deep-Sea Thermal Energy
Research at the University of Malta is evaluating the possibility of using offshore wind turbines in deep waters to exploit wind energy at the same time as making use of the enormous renewable thermal energy resources available in deep-sea cold water. The concept is based on the direct coupling of offshore wind turbines to positive displacement pumps, replacing the gearbox and electrical generator found in conventional systems. Rather than producing electricity directly, individual wind turbines would pump pressurised deep sea water to a centralised hydroelectric power station. After producing electricity, the sea water is pumped through a heat exchanger to provide district cooling. The idea of using cold water below the thermocline layer and offshore wind energy to extract it has evolved into the Offshore Wind and Thermocline Energy Production (OWTEP) system.
By Mr Daniel Buhagiar and Prof. Ing. Tonio Sant, Department of Mechanical Engineering, University of Malta
- Category: Articles
Taking a Closer Look at Faulting and Seismic Hazards for Wind Farms
Across much of the world earthquake activity is a common occurrence. Although some places have more seismic activity than others, hazards from earthquakes may have a wider reaching long-term impact on wind farms than that expected by many in the design community. Even though a site may not have recent seismic activity, this does not preclude it from future seismic shaking or ground rupture. Within areas that have active seismic motion, seismic and fault hazard investigations are an important part of project development. For those not familiar with these types of investigations there are various review components which can be obscure without a guideline for interpretation. Even for technical specialists, variable code requirements and local geologic differences make individual project reviews difficult to achieve if someone is not familiar with a standard guidance document. The intent of this article is to discuss these considerations during wind farm seismic evaluations.
By Daniel E. Kramer, Petralogix Engineering, and Garret Hubbart, Neil O. Anderson & Associates, USA
- Category: Articles
Developing and Testing Solutions for a Compact and Efficient Offshore Wind Turbine
For weight, size and cost reasons it is common to employ a mechanical gearbox in a wind turbine generator; however, mechanical gearboxes have disadvantages including reliability, acoustic noise, mechanical vibration and maintenance requirements. A direct drive machine removes many issues, but the size, mass and cost of the turbine may be compromised. In this article the development and testing of a magnetically geared generator and a nacelle structure using a kingpin attachment are discussed. This combination seems to offer both efficiency and a low cost of energy as well as being much more lightweight than traditional solutions.
By Chris Kirby and Stuart Calverley, Magnomatics Limited, and Ewoud Stehouwer and Ben Hendriks,, DNV GL, UK
