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- Category: Articles
A Serialised and Standardised Product Platform for Wind Drives
NGC StanGear is a serialised product platform based on an application database, standardisation, and a modularisation concept for wind gearboxes. The approach of NGC is based on its experience of over 50,000 NGC main gearboxes supplied to the market worldwide as well as a comprehensive data analysis of the turbine and gearbox market. The database includes operational parameters for different power classes. From the technology side, the different materials, manufacturing methods and design features have also been considered.
By Dr-Ing. Valentin Meimann, Mr Yizhong Sun, Mr Sudong Li, Mr Aimin He and Dr-Ing. Jianhui Gou, Germany and China
- Category: Articles
Operation Beyond Design Life
According to IEC 61400 [1], the lifetime of a wind turbine is a minimum of 20 years . However, differences between the design loads and the actual loads on site can lead to the possibility of operating the wind energy converter (WEC) longer than the design life. Using an aeroelastic simulation the individual overall lifetime can be calculated for each main component.
By Jürgen Holzmüller, President, 8.2 Group, Germany
- Category: Articles
Investigating the Causes and Mitigating the Risks
Edgewise vibration (EV) is an aeroelastic resonant phenomenon induced by the wind that can occur when a wind turbine is parked with a brake applied or idling (e.g. not producing power). While EV is an infrequent event, the authors have conducted several blade failure investigations that identified EV as the mechanism of failure. The investigations involved blades designed and manufactured by multiple entities, with blade lengths ranging from approximately 40 metres to more than 80 metres. This range encompasses most utility-scale blade lengths currently in production. EV is a specific case of vortex-induced vibration, where shed vortices in fluid flow around a structure impart forces to the structure, resulting in oscillatory motion. EV is characterised by increasing blade deflections (Figure 1), primarily in the edgewise direction, that (for the context of this article) results in blade damage.
By M. Malkin, Principal Engineer, and D. Griffin, Senior Principal Engineer, DNV GL, USA
- Category: Articles
Problems Faced in Service Life Estimation of Blade Bearings
The blade bearings of wind turbines allow the required oscillation to control the loads and power of the wind turbine. The pitch system brings the blade to the desired position by adapting the aerodynamic angle of attack. The pitch bearing, which is connected to the blade and the hub of the turbine, is subjected to high axial forces and bending moments. The conditions of these bearings are unique and most standards to estimate bearing service life are designed for rotating bearings and do not consider the oscillation. This article gives a brief overview of the current problems of blade bearings. The article focuses on the tribological challenges like fatigue life calculation of oscillating bearings, different wear damage modes like false brinelling and fretting wear, grease lubrication and the contact conditions occurring under different operating environments.
By Fabian Schwack and Prof. Dr.-Ing. Gerhard Poll, Institute of Machine Design and Tribology, Germany
- Category: Articles
Spinner Anemometer Provides Transparency in the Performance of All Turbines in a Wind Farm
Wind turbines are energy producing devices. Hence it is important for the customer and the manufacturer to know if a turbine efficiently converts the kinetic energy from the given wind conditions into power. This power performance characteristic is commonly expressed as electrical power (output) versus horizontal wind speed (input) measured under free inflow conditions at a distance of two to four rotor diameters in front of the turbine. Here is where the big dilemma in the wind industry lies.
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On the one hand every turbine should be monitored to make sure its performance characteristic is within the specification, but on the other hand it is almost impossible to measure the wind quantities at all turbines and at all sites, using met masts or other non-standard forward-looking measurement systems.
By Harald Hohlen, ROMO Wind
- Category: Articles
Security and Protection Using Sensor Systems
Sensor systems for offshore wind farms are used for the monitoring of many environmental and operational parameters. They monitor the internal turbine and loads condition, and also the environment of offshore wind farms. Wind speeds, wave heights and swell, as well as parameters related to the turbine condition such as oil temperature or pressure or rotor speed, are measured by sensor systems. However, sensors are also vital for safety and security. Each offshore wind farm element must be equipped with a fire detection system, which is based on sensor information. Access restrictions to sensitive areas (e.g. the monitoring room or nacelle) are also managed by sensors, and sensor systems guarantee the safe condition and positioning of rotor and nacelle (yaw system). The research project OWiSS, which is described below, focuses in particular on the safety and security issues.
By Julia Klatt, Deutsche Offshore Consult, Germany
- Category: Articles
Developments in Mooring Installation Technology for Floating Offshore Wind Structures
As floating wind turbines move into deeper waters, the capital expenditure (CAPEX) costs for mooring and installation will contribute a significant proportion of the overall project budget. Offshore wind developers are looking for a new mooring methodology to reduce costs, minimise installation times and reduce health and safety risks. The mooring of offshore wind platforms has been identified as the critical success factor in the future of floating offshore wind. High installation costs and the cost of anchoring are delaying and restricting the commercialisation of the sector.
By Greg Campbell-Smith, Global Business Development Manager, First Subsea, UK
