Wind power to be checked for speed to be improved

“The queuing phenomenon of low-voltage ride through detection of wind turbines is the result of a series of factors, but this phenomenon is temporary and is gradually easing.” Liu Chun, deputy director of the Institute of New Energy, China Electric Power Research Institute, was interviewed by the reporter recently Said.

With the rapid development of wind power, the impact of large-scale wind power grid interconnection on the safe operation of power grids has become increasingly apparent. This has also put forward higher requirements for technical standards and testing of wind power grid integration.

There are hidden dangers of grid-connected security in multiple links With the continuous growth of wind power installations, the impact of wind power on the power grid has gradually expanded from the local grid to the main grid. In recent years, there have been frequent occurrences of wind turbine off-grid accidents. With the increase of wind power grid-connected capacity, this impact has become increasingly serious. Even the common faults in a wind farm collecting system or system voltage caused by nearby short-circuit faults Fluctuations will cause large-scale wind turbines to escape the net. If this trend of failure continues, it will lead to the disintegration of the local power grid and even to a large-scale blackout. Therefore, it is of great significance to improve the safety of wind power by means of strengthening wind farms and grid management.

Liu Chun said that at present, wind power from design, construction to all aspects of grid operation, there are certain problems in the safety of the grid, and the accumulation of these problems caused a large area of ​​off-grid accidents. Taking the large-scale wind power off-grid accidents that occurred several times last year as an example, the process of its occurrence and development has repeatedly prompted us to present grid-connected safety problems in multiple links, and eventually led to the gradual development of small faults within a wind farm into large-scale wind turbines. Net loss accident. If the grid connection performance of the wind turbine fails to meet the requirements, the voltage drop of the system will cause most of the wind turbines without low voltage ride-through capability to be disconnected. After a unit that does not have low-voltage ride-through capability is removed from the grid, the reactive power regulation system of the wind farm does not meet the requirements of the grid-connected standards. As a result, the system voltage rises, causing the remaining wind turbines to be disconnected due to high voltage, and a large area fan is eventually formed. Network accidents. In response to these problems, the State Electricity Regulatory Commission and the National Energy Administration have put forward rectification requirements and have made specific technical requirements and rectification provisions for the problems exposed.

The progress of wind turbine testing needs to be gradually improved. At present, national technical standards for grid connection of wind power are not yet announced. Standards for centralized control of wind farms and design specifications for converged systems, design specifications for access systems, and design specifications for monitoring systems are still under development. Therefore, the detection workload is large to some extent, and the problem that the single-machine detection time is too long exists.

According to Liu Chun, China National Electric Power Research Institute, as the operation and maintenance unit of the national R&D (experimental) center for large-scale wind power grid-connected systems, although the detection capability and efficiency have reached the world's leading level, the current detection capability can only meet new grid-connected networks. Wind farm and new production wind turbine testing requirements.

For the current situation of wind power generator grid-connected testing that is reflected in the industry, there are several factors that restrict the inspection: First, there are a large number of wind turbine generators, and there are too many historical debts, and the detection requirements have a certain concentration and explosiveness. . For example, a large number of wind farms that have been put into operation without low-voltage ride-through capability have undergone sampling inspections since the last year. There are also a large number of wind turbine generators used in newly-built wind farms and have been put into production. The models used are urgently needed to be connected to the grid. Before passing the test, this has caused the situation of waiting for inspection to happen.

The second is that the time required for the wind turbine to pass the test is longer. China's wind turbine manufacturers generally do not establish their own perfect test conditions. The low-voltage ride-through performance of the tested wind turbines has not been debugged and verified before inspection. In 2011, more than 70% of the testing equipment was used to help the company debug and improve the performance of the wind turbine. The longer detection time of the wind turbine affected the detection efficiency. In 2012, the time taken for the commissioning and improvement of the dispatched wind turbine has not exceeded 50%, which indicates that the low-voltage ride-through performance of the wind turbine has been greatly improved. The improvement of the unit performance has greatly accelerated the inspection speed. In the first two months of this year, the Zhangbei base completed 9 low-voltage ride through tests.

The third is to perform wind turbine low voltage ride through detection and wait for proper wind conditions. Wind power grid-connected detection must be performed under certain wind conditions. Low-voltage ride-through performance requires wind turbine output to exceed 90% when detecting windy conditions. Last year, the nation’s wind energy resources were very unsatisfactory, and winds were significantly lower than in previous years. Detection equipment was in many cases waiting for the wind, which greatly affected the detection efficiency.

Liu Chun said that with the development of wind power technology in China and the improvement of testing capabilities, the problem of slow progress caused by the queuing inspection of wind turbines will no longer occur.

Perfecting the grid-connected wind power evaluation system The grid-connected performance of the wind turbine unit equipment has become the main factor affecting the safe and stable operation of the grid. In addition to the grid-connected testing of the wind turbine, the requirements for the newly-accepted wind turbines installed in the grid are required. Only after passing the test can it be put into use.

Liu Chun told reporters that after a new model fan goes offline, it needs to be certified. In general, this certification starts with design evaluation. In addition to the design assessment, a factory inspection is also required. Its purpose is to ensure that the manufacturing process meets the requirements of the design, the quality management system is reviewed, and tests are performed because different certification guidelines require different tests. In addition, in the factory debugging, different manufacturers due to different designs, the specific process of the factory commissioning is not the same, but also after more than a dozen items of inspection.

For the next step will be how to improve the detection capability, Liu Chun said that it is necessary to establish a sound evaluation system for wind power grid integration. Mainly include establishing wind turbine component testing capabilities such as converters, main controllers and variable pitch systems, improving wind turbine model validation and low-voltage ride-through assessment capabilities, and establishing wind farm evaluation capabilities. To provide technical support for the evaluation of wind power grid integration safety.