Power Dev PowerDev_April2012 : Page 6
APRIL 2012 ISSUE N°5 INDUSTR Y REVIEW Full power: Siemens’ direct drive wind turbines use permanent magnets to excite the synchronous generators, whose output is converter to electricity ready for entry into distribution grids by full converter architectures. (Courtesy of Siemens) Wind turbine converter choices pave way for grid parity charge Turbine designs and how components are sourced will play a big part in delivering wind power that can compete directly with other electricity generation technology, ABB, AMSC, Goldwind, Siemens Wind Power and Vestas tell Andy Extance. W 6 ind power technology seems particularly able to cause disagreement, controversy and con ﬂ ict. It could be unease at their environmental impact, political arguments over subsidies or the ﬁ erce rivalry between manufacturers serving the sector. In today’s world, still struggling to overcome recent ﬁ nancial crises, those disputes are even more bitter. Nevertheless, companies POWER Dev’
Wind turbine converter choices pave way for grid parity charge
Turbine designs and how components are sourced will play a big part in delivering wind power that can compete directly with other electricity generation technology, ABB, AMSC, Goldwind, Siemens Wind Power and Vestas tell Andy Extance.
Wind power technology seems particularly able to cause disagreement, controversy and conflict. It could be unease at their environmental impact, political arguments over subsidies or the fierce rivalry between manufacturers serving the sector. In today’s world, still struggling to overcome recent financial crises, those disputes are even more bitter. Nevertheless, companies Competing in the sector persist, as they feel that they are nearing a world where wind power is a sustainably profitable, well-established, industry.
Political and economic concerns affect wind power’s prospects, noted Beijing, China, headquartered turbine producer Goldwind. “Wind energy is still in a phase that depends on good economics and stable incentives,” Kerry Zhou, director of the company’s group strategy department told Power Dev’. “Trade disagreements have been sparked in wind Turbine markets as countries support ‘domestic’ industries. As a result of the global downturn, lack of investment and capital are hurting developers who want to install wind turbines. These issues have had an effect on revenues for wind turbine manufacturers.”
Goldwind at least is set to benefit from policies favoring domestic producers, thanks to its location and the experience it has accumulated since its foundation in 1998. “After over 5 years’ fast growth, the Chinese wind market is entering into a more stable and healthy development phase,” Zhou said. “The market will look more for product quality and power generation efficiency. This definitely benefits the industry leading companies like Goldwind.”
The prospects for wind power markets in the developed world are less clear, said Teijo Kärnä, Wind Market Manager located at ABB Oy in Helsinki. “It’s still not clear if the US will continue with the credit programmes that have been up and running for several years,” he said. “They have been renewed several times, but if they’re not prolonged after 2012 then that would surely affect the market in the US. The uncertainty in the European economies is also an influence. We see that Spain is withdrawing some incentives, for example. People are more careful now because the market still depends heavily on government support in seeking direction and investment.”
With incentives for wind power threatened in some countries, turbines must be more competitive with other forms of power generation. “Each manufacturer has launched programmes to cut costs,” underlined Kärnä.
“The market is talking about grid parity, so that it can compete with other modes of energy production.” ABB thinks that one way to achieve this is to standardize modules and components used across the industry, to get the benefits that come with higher manufacturing volumes. “We believe the way to bring down the turbines’ cost is with standard solutions and platform products,” Kärnä said. “Start with the generator, gearboxes and convertors. Don’t make each turbine too individual, rely on proven solutions and packages of products that are designed to work together.”
Anders Vedel, Executive Vice President and Chief Technology Officer at Vestas Turbines R&D in Denmark agrees that times are tough in the wind power industry. “In many countries, the political attention to renewable energy is overshadowed by severe economic challenges,” he said. “There are rapid rises and falls of political and economic power as well as shifts in trends and technologies – all affecting consumer behavior. Closing our eyes and ears for this development is not how we choose to go forward. We must face these changes. But looking into the future even with open eyes, the visibility is poor. For 2012, and especially 2013, the outlook for wind and Vestas is like looking into a fog when you are driving in your car: You know you are moving; but you have to slow down and rest your foot on the brake, because turning on your headlights at full power is not going to help you. That fog is quite similar to what the future looks like for most companies right now – including Vestas.”
As part of its efforts to compete against other power sources, Vestas has restructured itself and now it is more positive about its prospects. “We have chosen to reorganize our global organization and cut our fixed cost significantly to become an even more agile company that is closer to our customers,” Vedel said. “Even though renewable energy may seem to be losing momentum in parts off the world, the EU is sticking to its green targets. In fact, Germany has decided to shut down all of its nuclear power plants over the next ten years. Therefore renewable energy continues to progress, not least because across the world wind power is becoming able to compete better with fossil fuels.”
Adapting to needs
Another way to deliver low wind power costs is through high efficiency turbines, which can be delivered by considering electricity generation methods. Permanent magnet direct drive (PMDD) generators are becoming more popular for this reason. The magnets save some of the energy otherwise needed to pass through coils and create the field that excites the generator. This influences the power electronic design of the turbine, requiring a full converter, which all Of the power generated by the turbine fl ows through. By contrast in double-fed induction generator (DFIG) architectures about two thirds of the power goes through part of the generator known as the stator and does not need to be converted with power electronics before it enters the grid. The remaining third goes through the rotor, and does need conversion. According to Henrik Stiesdal, Chief Technology Officer Siemens Wind Power, the benefit PMDD brings is becoming more widely appreciated. “It appears that all major players are shifting to full converters,” he said. “We believe this is the obvious choice. Siemens has always used a full converter.”
Goldwind also noted that DFIG designs must meet increasingly tight rules, for example ensuring that they remain connected to the grid when voltages dip. “They will be pushed to modify the existing configuration, which increases cost,” Zhou said. “Full converters adopted by PMDD have natural advantages already blended into their design. In the long run, PMDD has demonstrated better performance in cost of energy during turbine operating period, and expected to have more cost advantage over the turbine life time span.”
Devens, Massachusetts, based AMSC (American Superconductor Corporation) believes the best way to get costs down is by selecting the right parts for each application. “We are the only supplier of converters who also design complete wind turbines,” said Tim Poor, Executive Vice President at the company. “We utilized that when we purpose designed our Power Module building block from scratch, specifically for wind. We don’t use the pre-assemblies for example from Semikron or Vacon because their performance and efficiency isn’t optimized for wind applications. The upside is they’re made in volume and are competitively priced. But we chose to do our own, because AMSC has strong competency in power electronics. For the other components, everyone has different ways to design. Chokes or inductors are almost a commodity. Capacitors, filter systems, we haven’t seen any kind of pre-assembly of those components that results in any cost savings for us. By custom designing the whole converter we optimize for the best possible performance, the lowest cost of energy.”
But ABB feels that design standardisation across the industry would also enable it to provide pre-assembled modules optimized for wind power if customer needs and interests would move towards this option. “Customers have preferred the complete grid compatibility tested converter solution, but technically we do not have any obstacle to taking the same approach”, said Teijo Kärnä.
Larger turbines are the best way to cut wind power costs, Kärnä noted. The places that offer enough wind to make that viable are offshore environments. “We see a big interest today in pilot units for large offshore turbines, so this market is definitely promising,” he said. When turbine power increases generator and converter voltages also have to be evaluated. Low voltage increases current, which generates heat, causing inefficiencies and losses. Raising voltage lowers current, reducing those losses, and going to medium voltage may reduce also the cable costs, Kärnä said. “3.3 kV is a good voltage level for turbine sizes up to 10 MW,” he added.
Looking out to sea
Offshore installation poses a much different challenge to projects based on land, AMSC’s Tim Poor explained. “Offshore, the main cost is installation, construction and setting foundations down in the seabed,” he said. “What drives that is weight. The heavier the top head mass is, the more infrastructure you need under the sea to make it work.” As a result, his company has designed lightweight high power turbines. “We have a 10 MW offshore turbine called SeaTitan,” he explained. “It’s not in production, but we have the design ready. It’s a fraction of the size of a conventional machine, with the same top head mass as today’s 5 MW technology. We’ve seen the potential for huge reductions in cost of energy using this technology and we’re excited about it.” Medium voltage ratings like 3.3 kV also bring extra power electronics considerations. “Existing low voltage 690 V IGBT technology Is already mass produced globally and as such very cost effective,” Poor said. “Medium voltage is not as mature for wind applications. The first cost is higher and there are additional safety considerations. You have to redesign the whole turbine power system to comply with standards, and personnel must be trained and certified to work on medium voltage. Longer term, the maintenance and repair costs are higher. These quickly eat into the savings that you get for the cables, so medium voltage doesn’t become economical until 6 MW or 7 MW. Then when you get bigger rotors and more efficient systems like this, I do think it is possible to use it to help get parity with conventional sources of energy.”
Siemens Wind Power’s Henrik Stiesdal said that such developments’ promise remains in the future. “The onshore turbine market is very important to Siemens, in comparison to the offshore market,” he observed. “The onshore market still accounts for the largest share of annual installed capacity.” As such, current market conditions favor low voltage designs, Stiesdal said. “Siemens considers below 1000 V optimal for wind turbine generators as that ensures their robustness,” he explained.
Vestas’ Anders Vedel agreed that onshore turbines remain dominant, but underlined that offshore installations are gaining importance. “The onshore market is our main market – no doubt about that,” he conceded. “It accounts for more than 95 per cent of our installed capacity. However, we still are a key player in the offshore segment. Vestas has delivered 47 per cent of the total installed offshore wind Energy capacity, and we expect that the offshore market is going to be of growing importance for us moving forward – especially in Northern Europe.” That growth comes because offshore turbines make wind power better able to achieve its main goal – providing the world’s demand for clean electricity, Vedel emphasized. “If offshore wind power plants covered just 10 per cent of the North Sea, they could Generate electricity equivalent to the total annual consumption of the 27 members of the EU,” he said. “The offshore potential for wind energy is enormous.”
Andy Extance for Yole Developmental
Anders Vedel is Executive Vice President and Chief Technology Officer of Vestas Turbine R&D. He is a member of Vestas top management, and responsible for research and development of technologies and wind turbines within the Vestas organization. Until a new Executive Vice President and CSSO for Global Solutions and Services he is also acting in this role. He is a mechanical engineer and has completed an executive development program at IMD, Switzerland. On top of that he has a diploma in service management. He has been working in Vestas since 1995, and he has a wide experience from several managerial positions within the global organization.
Henrik Stiesdal is Chief Technology Officer Siemens Wind Power. He is one of the pioneers of the modern wind industry. He built his first small wind turbine in 1976 and in1978 designed one of the first wind turbines representing the so-called “Danish Concept” which dominated the global wind industry through the 1980s. Stiesdal joined Bonus Energy in 1987. In 1988 he was appointed Technical Manager, and in 2000 Chief Technology Officer. During his career with Bonus Energy, now Siemens Wind Power Stiesdal has worked with all aspects of wind turbine technology and has also played a major role in the company’s business development.
Tim Poor is Executive Vice President at AMSC, responsible for leading the company’s wind business unit as well as the company’s global sales and business development activities. He joined AMSC in September 2001 as Director of Sales and Business Development for Power Electronic Systems and has held a number of executive positions at the company since then. Prior to joining AMSC, Mr. Poor worked at General Electric (GE) for seven years in the Commercial and Industrial division. Prior to GE, Poor was an engineering consultant at Arthur Andersen & Company. Poor is a native of Indiana and holds a B.S. degree in Industrial Technology from Purdue University.
Teijo Kärnä, is Wind Market Manager located at ABB Oy in Helsinki. Kärnä has worked with sales and management roles related to Wind Power Generators and other electrical components for wind since 2001. Today he coordinates ABB’s offering for electrical components in wind turbines such as Generators, Converters, and PLCs. He is a member of ABB’s Wind Market Management group.
Kerry Zhou is director of Goldwind’s group strategy department
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