The mother ship carries the OceanAlpha M80 USV to the survey area and releases the USV. With 3D real-time sonar, the OceanAlpha M80 USV survey and detects the pile foundation and cable routing according to the planned mission route. The operator can receive the detection data sent back from the USV in real time through the private network on the mother ship.
China General Nuclear Power Group (CGN) Ruhai Wind Farm is located in the Yellow Sea in the east of Rudong, Jiangsu Province. It was oﬃcially operated on September 8, 2016. As the pile foundation erosion of wind farms and the partial exposure and suspension of submarine cables may easily aﬀect the safety production of oﬀshore wind power, the pile foundation and submarine cable erosion detection should be carried out regularly in wind farms.
Pile foundation and sea cable scour hazard
The traditional survey using workboat costs high and the detection process is affected by the size and draft of the workboat. It is difficult to operate manually when surveying between wind turbines because of collision risk and lower work efficiency. Therefore, a new type of survey solution is needed to meet the demand for wind farm survey.
CGN group adopts OceanAlpha M80 USV and Echoscope 4G version of Coda Octopus real-time 3D sonar to detect wind power pile foundations and submarine cables.
The advantages of USV for pile foundation and submarine cable detection:
① Smaller hull size is flexible and efficient
② Intelligent collision avoidance reducing the risk of collision
③ Accurate line tracking and reliable data quality
④ No human wading risk
03 Survey work：
The OceanAlpha M80 USV can sail from the wharf or operate with the mother ship (operation and maintenance boat). Real-time data is sent via public network, private network, satellite communication, or the communication link between the booster station and the land. The operator can effectively support the pile foundation and cable scour detection of the wind power plant on the shore or on the mother ship.
Survey process flow chart
The OceanAlpha M80 USV can sail autonomously according to the position of the pile foundation and the route of the sea cable, and the maximum deviation of the position is less than 1m. At the same time, the mission line can be saved for future survey and historical data comparisons.
USV survey and observation around the pile foundation
This project is the first case in China where USV are used to survey pile foundations and submarine cable scour in wind farms. The USV`s characteristics of maneuverability, flexibility, and high safety can make up for the limitations of conventional survey platforms operating in complex environments and harsh waters, and solve traditional operational problems by using a new way.
Compared with the maintenance work of a conventional workboat, USV has higher positioning and control accuracy, and the flexible turning radius of the hull is a small and low risk of collision. The accurate line tracking performance increases survey efficiency.
In addition, the use of USV cooperative surveys can greatly improve efficiency and reduce carbon emissions. Taking an offshore wind farm survey mission with an area of 50 square kilometers as an example, with one mother vessel and 4 USVs surveying in a cooperative way, the overall survey time could decrease 75% and reduce 83% fuel consumption and carbon emission.
In the future, USV will better utilize the characteristics of intelligence, efficiency, precision and safety, carry out various tasks by carrying different loads, replace traditional manpower for high-intensity, high-risk and repetitive offshore operations, and promote the offshore wind power industry. Enter the era of intelligence and unmanned.