Risk analysis and prevention and control of offshore wind power

Key words:Offshore wind power; wind power enterprises; wind power accidents; wind power safety

1. China's offshore wind power market

In 2019, China's newly installed offshore wind power capacity was distributed in seven provinces and cities in Jiangsu, Guangdong, Fujian, Liaoning, Hebei, Zhejiang and Shanghai. Among them, Jiangsu’s newly installed offshore wind power capacity reached 1.6 GW, accounting for 64% of the country’s newly installed capacity, followed by Guangdong 14%, Fujian 8%, Liaoning 6%, Hebei 5%, and Zhejiang 3%. As of the end of 2019, the cumulative installed capacity of offshore wind power in Jiangsu Province exceeded 4.7 GW, accounting for 67% of the cumulative installed capacity of all offshore wind power. Followed by Fujian, accounting for 7.0%, Guangdong accounting for 6.5%, Shanghai accounting for 5.9%, Hebei accounting for 4.2%, and the total installed capacity of the remaining four provinces accounted for approximately 9.2% (Figure 2). At present, 11 coastal provinces across the country have carried out offshore wind power planning research work, and nine provinces including Jiangsu, Fujian, Shandong, Guangdong, Zhejiang, Shanghai, Hebei, Hainan and Liaoning have prepared offshore wind power development plans and obtained approval from the National Energy Administration .

Distribution of cumulative installed capacity of offshore wind power in China's coastal provinces (cities)

(Data as of the end of 2019, image source: CWEA)

2. Common risks of offshore wind power

2.1 Natural disaster risk 

When it comes to the risks of offshore wind power, the first thing that is noticed is the risks of natural disasters such as typhoons, lightning strikes, and earthquakes. Among them, typhoon risk has received the most attention. The southeastern coast of my country is an area with a high incidence of typhoons every year. At the same time, typhoons are rare weather conditions in European countries that developed offshore wind power in the early days. We don't have much experience to learn from, so people's worries about typhoon risks have increased. Fortunately, since the completion of the first offshore wind farm in 2010, no serious accidents such as the collapse of offshore wind turbine towers caused by typhoons have occurred. Various fan manufacturers continue to introduce "anti-typhoon" fans, and continue to make technical improvements in practice.
Risk prevention and control measures
The wind turbine design must accurately calculate the load under the typhoon and consider sufficient safety margins according to the new design specification.Focus on the performance design and production quality of core components such as yaw and pitch, to ensure that the wind turbine can operate according to the designed control strategy under typhoon conditions.The trajectory of the typhoon shall be closely tracked, and the necessary preparations for combating the typhoon shall be completed 24-48 hours before, including: checking the operating status of the wind turbines, the status of the power grid, the standby power supply, and strengthening the special components.When a strong typhoon strikes, you need to stop the machine, the blades are pitched to the feathering angle, and the automatic yaw mode is entered. The front of the wind wheel is aligned with the wind direction in real time to ensure the minimum load of the typhoon on the wind wheel.

2.2 Risk of submarine cable damage 

In multiple statistical methods, the risk of submarine cable damage is the risk with the largest proportion of losses, which can usually reach 80%. Some European wind power experts even believe that on average, submarine cables will be damaged once every two wind farms. One of the most common risks is damage caused by external forces such as fishing activities and ship anchoring. In addition to geological changes, access protection, and submarine cable quality will also affect the safety of submarine cables. Risk prevention and control measures Special attention should be paid to the safety of submarine cables in the sea areas where fishing activities are frequent and the main passage areas of ships are to ensure the depth of cable excavation and avoid unpredictable external damage. Special consideration should be given to factors such as seawater erosion to avoid risks caused by exposure of the submarine cable after a certain period of time. Strengthen the protection for the landing section of the submarine cable, and use special protection such as J-tubes for the wind turbine connection section to avoid damage caused by bending.

2.3 Foundation construction risks 

In the foundation construction of offshore wind power, due to the complexity of the seabed geology and other factors, the most common major risks are pile sliding and hammering. For example, the pile slipping accident occurred in Taiwan's offshore wind farm this year. According to the hammer or sliding pile will cause damage to the pile hammer and pile, and have a greater impact on the construction period. Risk prevention and control measures The geotechnical exploration of the seabed is more detailed and accurate, and the uncertainty of exploration and construction is fully considered in the design plan. Reasonably choose piling hammers and construction procedures. Strengthen on-site pile sinking monitoring.

2.4 Risks of lifting operations 

Lifting operations cover all aspects of offshore wind power, including foundations, booster stations, wind turbines, submarine cables, component transportation, and tool transfers. Lifting operations involve a lot of personnel, tooling, and tools, and the operation time is long. The structure of offshore wind power projects is complex, and cross-working construction often exists. Special operations include electric welding (gas cutting) operations, hoisting operations, drilling rig operations, etc., combined with the large size, heavy weight, and non-standard structure of the crane, the operation process is more dangerous, and there are high requirements for on-site safety management . Risk prevention and control measures Develop a strict lifting plan, and scientifically arrange the lifting capacity, path, time, arrangement of auxiliary operations, weather restrictions, site restrictions, and communication. Before each hook starts operation, the lifting equipment, tooling, and tools shall be inspected by qualified personnel; the hook lifting actions, staffing, job responsibilities, and emergency arrangements shall be confirmed in the pre-shift meeting. Strictly implement lifting disciplines, do not violate regulations, and do not barbarous operations. 

2.5 Fire risk 

Fire has always been one of the main sources of risk that offshore wind power needs to face. According to statistics, the global power loss of onshore and offshore wind farms caused by fires accounts for 10% to 30% of all causes. Whether it is the wind turbine body, the booster station, or the operation and maintenance ship, it is necessary to take effective fire prevention and fire fighting measures to prevent the fire from causing huge personnel and property losses. Risk prevention and control measures In the special period of rush installation, special attention must be paid to the fire prevention of equipment. Due to the formation of the actual seller's market, certain hidden dangers may be caused to the quality of the product. Special attention is paid to elements such as lightning protection, electrical safety, oil leakage, and mechanical friction. Special design is required for fire prevention during the construction phase, such as the equipment of fire extinguishers, the management of hot work, the arrangement of hot spots, and the management of personnel.

Picture and text from International Energy Network

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