Wind power by international co-operation

CHINA: The breathtaking growth of China's wind power industry in recent years has resulted in the installation of over 21,500 wind turbines with around 26GW capacity by the end of 2009.

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But a number of problems persist, such as inaccurate wind power resource assessment, a poor national standard for integrating wind power to the grid, and inconsistent planning of operations in the industry.

China has looked abroad to learn from the experience of countries with more mature wind power sectors and to discover new technologies.

One such effort is a renewable energies technical assistance programme between the governments of China and Denmark, which began in 2006 and concludes this year.

The Wind Energy Development Programme (WED) covers four areas: wind resources assessment; wind energy project planning and evaluation; grid integration of wind power; and training and information disclosure.

It has a budget of CNY 87 million ($12.7 million) and financial support from the Danish International Development Agency.

"The WED project aims to support the Chinese government to create a better environment for the growth of wind energy from different aspects, including how to overcome policy, management and technical barriers," says Dong Luying, director of the WED project management office.

The project, says Dong, was originally implemented in Heilongjiang, Jilin and Liaoning provinces in north-eastern China, and the tasks scheduled there under the project have already been completed.

Accurate assessments

Fluctuations in wind speed and direction make it hard to integrate wind power onto the grid, and the Chinese needed an approach to solving this problem.

"Many countries have accumulated rich experiences in wind resource assessment. Take Denmark, whose wind power constitutes about 20% of its electric supply mix. Its experiences are surely worth learning," says Dong.

The wind resource assessment component of the project was jointly conducted in the three provinces by China Meteorology Administration (CMA) and the Danish national research laboratory Risø DTU.

Twelve meteorological (met) masts, 70 metres high and equipped with double sensors, collected data for 18 months and, compared with data from 180 existing met masts held by CMA, created a wind atlas of north-east China.

"With the new atlas, developers and design institutes will have more accurate reference data for more reliable wind resource assessment in the future, which will enable better wind farm planning," says Dong, adding that these methods have been applied in 400 wind resource assessment outlets across the country, and will be promoted and applied nationwide.

Previously, China had made two nationwide measurements of wind resources, showing it has 253GW exploitable onshore wind resources available and 750GW offshore wind resources 10 metres above the ground or sea level, along with 2,380GW exploitable onshore wind resources and 200GW offshore wind resources 50 metres above the surface.

Revised grid code

The fluctuation in the wind affects the integration of wind power onto the electricity grid, and the higher the proportion of wind power, the more difficult it becomes to manage.

In China, the absence of a national grid standard is another major barrier impeding large-scale grid integration.

"At the outset, we bought wind turbines from abroad. Wind farms largely focused on basic power generation functions of the turbines and neglected to import advanced technologies, such as voltage control and anti-interference low-voltage ride-through technology," says Chi Yongning, assistant chief engineer of the new energy department of China Electric Power Research Institute (CEPRI).

This is in sharp contrast to European practice, where technical and management procedures are required before a turbine can generate and send wind power to the grid.

"As a result, in China, when wind farms integrate power to the grid, the grid meets many potential threats," says Chi.

In December 2005, the State Bureau of Technical Supervision introduced the Technical Rule for Connecting Wind Farm to Power Network, drafted by CEPRI. But, says Chi: "The version presented a very low standard considering wind farm scales and turbine manufacturing technologies at that time."

According to Dong, under the support of the WED project, CEPRI launched a programme to study the grid capacity for accommodating wind power in Heilongjiang, Jilin and Liaoning provinces.

This established the existing grid capacity, the possible solution for future development, and has also developed the analysis methodology.

The study of grid integration for Xiangyang Wind Farm in Jilin, a key link, has paved the way to search for solutions to grid interconnection obstacles.

CEPRI has since improved specific technical requirements for wind farms by applying international standards and best-practice experiences, particularly regarding active and reactive power, voltage range and regulation, low-voltage ride-through, and grid integration compliance testing of wind farms.

The revisions will upgrade the national grid code, to be issued at the end of the year, says Dong.

"The upgraded code will help to standardise the wind power market, ensure wind turbine quality and the safety and stability of the power grids," she says.

Inconsistency in the programming of wind farms and power grids has been another problem for the booming Chinese wind power industry.

"In foreign countries, wind farm investors are highly concerned with the grid integration conditions," says Chi. "Before making the investment, they will see if the wind power could be connected to the grid and sent out, and if the wind turbines could meet the requirements of the grids.

"But in China, wind farm investors are generally focusing on making enclosures in wind rich areas, such as north China’s Inner Mongolia and north-west China’s Gansu and Xinjiang.

"They forget these areas have few electric power users and the grid has to send the power to east and central China users over long distances," Chi says.

"In fact," he adds, "the grid integration and transmission capacities are closely associated with the costs of developing wind farms.

As power grid construction lags behind wind farm construction, because many large wind power projects are separated into smaller 49.5MW stages to shun central government approval, many wind farms have problems sending out electric power after operation," says Chi.

Take Inner Mongolia. About a third of the turbines lie idle, particularly on winter nights, as the local grid, admitting wind power to make up 27.6% of power at the end of 2009, cannot take on more wind power without compromising the safety of the grid, says Zhang Fusheng, manager of Inner Mongolia Grid.

Inner Mongolia has only two 500kV connections to send electric power to the neighbouring North China Grid, which can only send out 3.9GW electric power at the most, far lower than the 30GW target of installed wind power capacity by 2015, approved by National Energy Bureau.

A fruitful result of the WED project, says Dong, is that it has created a template for wind power project feasibility studies that applies to Chinese conditions.

"This template stresses evaluating wind resources and making closer analysis of environments, energy conservation and risks," says Dong.

"It is of high reference values for scientifically constructing wind farms in the country, and is being promoted nationally."

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