Wherever it blows, TC work is essential

Wind at the forefront of renewables field

By Morand Fachot

Governments throughout the world are trying to increase the share of renewables in their electricity generation portfolio both as a precaution against fluctuating prices for fossil fuels and for environmental reasons. Wind power is currently the most cost-effective new renewable energy source and has expanded considerably in the last few decades. IEC TC (Technical Committee) 88: Wind turbines, has made this expansion possible by providing manufacturers and installers with International Standards which ensure that wind turbine installations are designed to time-tested requirements and evaluated according to proven procedures.

Offshore wind turbines (Photo: Vestas) Offshore wind turbines (Photo: Vestas)

Renewables gradually displacing fossil fuels

In its World Energy Outlook 2012, the IEA (International Energy Agency) forecasts that renewables could "become the world’s second-largest source of power generation by 2015 (…) and, by 2035, approach coal as the primary source of global electricity". The IEA places wind as the leading renewable source in a variety of scenarios.

Wind power has been used for centuries to propel ships or drive mills to grind grain or pump water. The conversion of wind energy into electrical energy (on a very limited scale initially) is relatively recent, dating back to the late 19th century. As the global quest for cleaner and sustainable sources of energy gathers pace, wind power is seen as offering great potential for growth in the renewable energies’ domain .

Wind astern

Between 2001 and 2011 wind power expanded 10-fold, at a CAGR (Compound Annual Growth Rate) of more than 25,5%, to reach 238 GW at the end of 2011. Extensive work by IEC TC 88 experts has underpinned that growth.

TC 88 was created in 1987, quite a few years before wind power became a major source of electrical energy at the global level.

Its scope, last formulated in 2002, is to prepare International Standards for wind turbines that "address design requirements, engineering integrity, measurement techniques and test procedures. Their purpose is to provide a basis for design, quality assurance and certification. The standards are concerned with all subsystems of wind turbines, such as mechanical and internal electrical systems, support structures and control and protection systems".

TC 88 International Standards have made it possible to manufacture better wind turbines and to extend the scope of their installation to encompass diverse and more challenging environments. The TC is preparing up-to-date International Standards, exploring new applications and making improvements to existing systems.

Complex TC structure

Experts from 38 countries take part in the TC's work which is constantly expanding to include all elements of wind turbine installation. The multiplicity and complexity of this task has led to a TC structure that includes two WGs (Working Groups), five PTs (project teams), nine MTs (maintenance teams), two JWGs (Joint Working Groups) and an ad hoc Group on terminology.

WG 3 is tasked with developing an International Standard on the design requirements for offshore wind turbines. These have specifications that differ from those of their onshore equivalents and wave loading represents an additional category that is required. WG 27 will define standard dynamic electrical simulation models for wind turbines and wind farms. The models will be used in power system and grid stability analyses.

PTs prepare International Standards for wind turbine installations and aspects that are not yet covered by their own specific standards. These include, among others, design requirements for floating offshore wind turbines, which present particular constraints, for rotor blades and for wind turbine towers and foundations. The MTs are tasked with updating existing International Standards and projects.

JWG 1 brings together experts from IEC TC 88 and from ISO (International Organization for Standardization) TC 60: Gears. They have prepared IEC 61400-4, Design requirements for wind turbine gearboxes, which is to be published shortly. Experts from IEC TC 88 and TC 57: Power systems management and associated information exchange, work together within JWG 25 to "develop standards for monitoring and control systems and associated information exchange for wind power plants".

Ever more wind on the horizon

The prospects for wind power are very positive: the IEA forecasts that installed onshore and offshore capacity will increase from 238 GW in 2011 to nearly 1 100 GW in 2035, with onshore capacity making up 84% of the total (against 98% in 2011). This expansion will require additional International Standards to cover new areas as well as an update of existing ones to support technical developments in the sector.

As of early November 2012, TC 88 had issued 18 publications, 14 International Standards and 4 Technical Specifications in the IEC 61400 series.

IEC International Standards for the wind turbine industry ensure that wind systems and installations meet the latest technical requirements. For installers, utilities and other users, they guarantee that the equipment they acquire and install is as safe, reliable and efficient as possible. They also ensure that the wind turbine industry will continue to prosper and make an ever larger contribution to electricity generation.

Offshore wind turbines (Photo: Vestas) Offshore wind turbines (Photo: Vestas)
Lifting assembled wind turbine drivetrain, generator and power unit in nacelle (Siemens press picture) Lifting assembled wind turbine drivetrain, generator and power unit in nacelle (Siemens press picture)
Jaisalmer wind farm, India (Photo: Suzlon) Jaisalmer wind farm, India (Photo: Suzlon)