By Andrew Williams

Wind turbines have had their share of teething problems, but so did many new technologies of the past. Tossing in the towel isn't an option.

However, given the sheer incidence of turbine failures, concerns have been raised that, in terms of measuring reliability, the current standards governing turbine technology testing are neither meaningful nor worthwhile. 

In response to these concerns, the National Renewable Energy Centre (Narec) in the UK plans to build a £15m marine test-rig in Blyth, Northumberland to enable it to perform certification activities, reliability and performance appraisal of new devices.  The facility will become one of the world’s largest open-access indoor test facilities for offshore wind turbines. 

Will testing conditions provided by Narec and others provide the industry with even more robust components and attract the vital private and corporate investment this energy sector requires?

Are current standards making the grade?

Commercial wind turbines currently pass through a 3rd-party Type Certification process against international standards.  

Certification focuses on overall product integrity and incorporates verification of sufficient fatigue and ultimate load capacity, safety system functionality and personnel safety measures.  

Full certification includes fatigue testing of blades plus verification of loads, power performance, noise and grid characteristics on a full-sized pre-production prototype turbine. 

However, reliability and maintainability are not formally considered, leading to calls for standards and guidelines that cover all aspects of turbine performance and which constantly evolve to keep pace with changes in the industry.

“Mother Nature is a severe parent.  Wind turbines ... are subjected to input energy excursions which, statistically, deliver an excessive impact to the machinery on unusual but regular occasions.  Can standards ever realistically cater for these worst cases?  As our wave pioneers keep telling us, the fifty-year wave has a habit of appearing in the first year,” says John Hill, Marketing Manager at Converteam Renewables.

New NAREC Facility

The Narec facility, due to be in action by late 2011, will test wind turbine nacelle up to 12MW with forced application to simulate ‘real world’ wind conditions and enable Type Certification testing of new turbines, as well as model verification and proof testing of prototypes. 

Other capabilities will include ‘post-mortem’ testing of in-service turbines, to reproduce measured loads and help diagnose the root causes of failure, and the running-in of new turbines to screen out early-life failures before offshore installation.

The test-rig will allow the whole turbine nacelle to be tested onshore and indoors before being taken offshore, thus reducing the technical and commercial risks of mass-production and deployment.

“The reliability issues the industry experiences are due to gaps in the current certification process and the test facilities proposed at Narec are needed to fill this gap,” says Jun Qiao, Strategy Manager at the Energy Technologies Institute (ETI).

Other Facilities under Construction

In the US, Clemson University has announced plans for an open-access facility in the state of South Carolina to provide high quality testing services to the wind turbine industry for turbines, drivetrains or gear boxes.

The testing facility will be housed in a former Navy warehouse adjacent to existing rail and ship handling infrastructure, and will be capable of full-scale testing of advanced drive-train systems for wind turbines in the 5-15 MW range.

Also in the US, a National Renewable Energy Laboratory (NREL) project is underway to test small wind turbine systems to industry and international standards.  In addition, NREL is working with the US Department of the Environment in defining its Regional Test Centers project, and is also collaborating with AWEA's Standards Coordinating Committee (SCC) and wind industry experts to develop national guidelines.

Is Narec's Facility Needed?

For Rex Tapp, Executive Vice President and General Manager at Horiba Instruments, the conditions being created by Narec are absolutely necessary for supporting business development, innovation, and risk management in turbine and wind farm deployment.

“In order to meet the aggressive 20% wind energy penetration targets by 2020 in the EU, system-level laboratory simulation testing capability is critical.  

This not only requires a facility suitable in size to support an entire nacelle, but also a wind simulator test-rig capable of recreating the forces, torque, and dynamics of the in-field [turbine] experience,” he says.

Hill also agrees that Narec is absolutely correct in its decision to build a complete, ‘hard’ simulation.

“The UK offshore wind initiative is an investment in capital plant, which the nation is installing in places where we don't want to plan to send people. 

“We will be erecting the prototypes of massive offshore turbines at safer, onshore sites, to allow Mother Nature to teach us some lessons, but we will also need to see the extreme conditions acting upon our inventions many times, in controlled conditions, to validate our design models,” he says.

As the wind industry expands, it is likely that large-scale test facilities such as those due to be established by Narec, Clemson University and others will become increasingly important in improving reliability and helping companies to address the major challenges posed by working in very harsh environments.

International collaboration will also be a vital element in standardising component capabilities, bringing down testing costs as well as building scale to this exciting segment of the world’s energy mix.

This article was updated on 10.08.10. The article previously incorrectly stated that Narec's test facility will test wind turbine nacelles up to 10MW; in fact, they will test wind turbine nacelle up to 12MW with forced application to simulate ‘real world’ wind conditions.

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Andrew Williams: TheGreenExpert@btinternet.com