New technical route expects to change market structure

Newspaper correspondent: Zhang Zirui 
China Energy Newspaper (March 14,2011, edition 23)

Wang Zhensheng, the general manager of Dalian SPARK New Energy Development Co.,Ltd, said to the correspondent on the Discussion Meeting of 3.0MW Wind Turbine Design  Proposal, “We are going to make a new type wind turbine, which is different from the conventional type. The wind turbine we are developing is driven by hydraulics.”

There isn’t any company in China that has been engaged in this type of hydraulic transmission wind turbine. “Around the world, only one company in Norway and one in the USA have manufactured prototypes of hydraulic transmission wind  turbine, but they are all for testing, no commercialized wind turbines have been launched yet.”, said Qi Tongqing, the senior member of China Wind Power Professional Commission, and senior consultant of China Classification Society (CCS).

Blaze a new path of R&D
According to the correspondent learned that the conventional wind turbines mainly consist of doubly fed wind turbines and direct drive wind turbines. Due to the incorporated gearbox, doubly fed type wind turbine has higher failure rate. And  though the direct drive type wind turbine doesn’t have any gearbox, the weight is even larger than the doubly fed type. Seen from the current market shares, direct drive type accounts for 30%, doubly fed type accounts for around 70%. These two types of wind turbines are not perfect, but they have been through the test of market for long time, and have been proven to be mature products.

Although in face of the market structure that has tended to be stable, Mr Wang Zhensheng said confidently to our correspondent that their hydraulic transmission wind turbine under development now is aimed at industrialization directly. To give up the proven technical route, and blaze a new path instead, will the hydraulic transmission wind turbine change the ruling market structure of doubly fed and direct drive wind turbines?

Hydraulic transmission wind turbine generator, just as its name implies, it adopts hydraulic flexible transmission. On the one hand, the hydraulic transmission replaces the rigid transmission of the gearbox used in the doubly fed wind  turbine, which solves high failure rate of gearbox transmission. On the other hand, the employment of hydraulic flexible transmission solves the problems in the direct drive type wind turbine, which includes high volume of generator, high consumption of copper, and high manufacturing costs. The technical manager of Dalian SPARK New Energy Development CO., Ltd introduced that the power generation system can either be installed on top of the tower or be arranged on the ground. Two different types of wind turbines can be produced according to the needs of different clients as well as different installation location. If the ground arrangement is adopted, a series of problems will be eliminated, for example, the difficulty in the nacelle maintenance will be reduced substantially.

Skillful subtraction to score successes with costs
In addition to a mature technology, cost is an unavoidable problem in order to realize the commercialized mass production. Only the wind turbine is of excellent performance and preferential price can be favored in the market.

The research and development of the hydraulic transmission wind turbine follows the idea of making subtraction. The applied parts are less, so the cost can be reduced naturally. According to the presentations, hydraulic transmission can realize speed increase, speed regulation and stable rotation speed, which eliminates the use of converters. Compared with the conventional wind turbine, the hydraulic transmission wind turbine eliminates the main components, such as converters, gearbox etc. Especially, it adopts synchronous excitation generator system, which makes both low voltage of 690V and high voltage of 10KV suitable as the power supply. If 10KV is used to connect with the grid for power generation, it can transmit power directly to the grid of 110 KV. Besides, in this way, the box type transformer can be saved, which makes it achieve the target of substantial reduction of comprehensive manufacturing costs.

Furthermore, as the main body section will be moved to operate on the ground, the daily maintenance costs can also be reduced substantially. In particular, the maintenance of this type of offshore wind turbine will be much more convenient and easier. It is estimated that the maintenance expenses can be saved by about 10%-15% annually if only considering the hoisting expenses during the maintenance. The power generation cost is reduced directly, and the equipment generating efficiency is increased in turn.

Offshore wind power is the tendency of the development of wind power industry. Hydraulic transmission wind turbine is more applicable to the offshore wind power than conventional wind turbines, which is one of the reasons for why Wang Zhensheng is so confident in the future market. The technical personnel told our correspondent that the main power generation system of the hydraulic transmission wind turbine is moved to operate on the ground. This decreases the cut-in speed which can be controlled less than 2.5m/s, besides, it can make flexible adjustment, switching over the quantity of driving motors according to the obtaining of wind energy to increase the single unit efficiency, and achieve the optimal power generation efficiency. In this way, the annual power generation hours and power output will be increased, and the increase is expected to be 3-5%. And it is more beneficial for the installation and maintenance of offshore wind turbine, and can be applied to the projects of floating ocean energy foundation.

Technical cooperation to conquer the challenges
Although the hydraulic transmission wind turbine has so many advantages, there are still some technical challenges are under solution. As for the challenges, some experts put forward: firstly, how to further increase the efficiency; secondly, how to solve get rid of the potential vibration caused by the hydraulic transmission which can lead to the looseness of fasteners; thirdly, how to prevent the hydraulic system from external leakage.

Wang Zhensheng frankly said “at the beginning of development, the challenges they have met with were more than what the experts have put forward. At the moment, most of these technical challenges have been solved.” In his words, “he doesn’t dare to discuss with the experts if he hasn’t got enough confidence.”

On the site of this discussion meeting, our correspondent found that there were not only scholars and professional experts, but also many suppliers of wind turbine supporting components from abroad, including supplier of  hydraulic pumps and motors-Bosch Rexroth Company, wind turbine bearings supplier-IMO Energy GmbH &Co.KG, Fritz Schur Energy A/S that supplies hydraulic pitch systems, as well as control system supplier-KK-electronic A/S. Wang Zhensheng said “they are not simple supplier, they are technical partners”

Wang Zhensheng told our correspondent that to develop and manufacture hydraulic transmission wind turbines of advanced level is a very sophisticated and challenging job, we must follow the route of resource integration and win-win. Therefore, we need to integrate the most advanced technology and enterprises worldwide and realize technical cooperation through project development.

It is learned that Dalian SPARK New Energy Development Co.Ltd has started the design of 1.5MW new type intelligent hydraulic transmission wind turbine before, currently, the assembly of the 1.5MW prototype has started, and it plans to complete the grid connection and power generation test in the June of this year. The design, trial production of 3.0MW prototype is performed gradually just based on the 1.5MW testing prototype.

“It is normal for a new technology to meet with problems. 1.5MW prototype is about to be installed completely, and connected to the grid to generate power, which will function as a very good test bench for 3.0MW, you can fish out many beneficial experience from it.” Xia Wuxiang, the introducer of the first wind turbine in China, told our correspondent.

Qi Tongqing said “wind turbine generator is a large system made up from many systems, so the method of system engineering must be adopted. The main characteristic of system engineering is overall design. The R&D of hydraulic transmission wind turbine needs to follow such technical solution route.”

“I came here with questions and doubts. Through the careful analysis of this discussion meeting, especially, after finding so many internally renowned enterprises are involved and the technical guarantee, I firmly believe that this wind turbine will develop and expand and its advantages will win the market and occupy the market definitely.” said bluntly Chen Xuesong, the deputy director of CGC of Beijing.

Xu Donghua, the researcher of Development Research Center of the State Council, expressed that only the continual efforts in both design and process and in the way of integrating the capital and technology can make the hydraulic wind turbine projects realize commercialization and marketization.

It is said that many of the state power groups have paid close attention to the hydraulic transmission wind turbine of Dalian SPARK. China Power Investment Corporation even intends to use this type of wind turbine on one of its projects. According to the plan of Dalian SPARK New Energy Development Co.,Ltd, in the following 3-5years they will apply their hydraulic transmission technology to the development of 5.0MW and above offshore wind turbine generators.