China's large engineering ship technology towards a high level of self-reliance

Wind power installation ship is a new kind of offshore engineering ship, mainly used for the transportation and hoisting of offshore wind power equipment. It integrates various functions such as component transportation, offshore operation, lifting and daily supply, and can independently complete the above-mentioned transportation and installation operations. Since Denmark built the world's first offshore wind farm in 1991, countries around the world have begun to build offshore wind power projects. Wind power installation equipment has experienced three generations of development: the first generation by the existing crane and transport barge combined operation; The second generation is a barge or platform with self-elevating function, but does not have self-propelled capability; The third generation of special wind power installation ship with self-propelled, self-lifting and lifting functions. At present, the wind power installation ships of foreign professional offshore wind power installation companies belong to the third generation, which are used for wind turbine installation, maintenance and other offshore operations. The "Seajacks Scylla" delivered by Samsung Heavy Industries in 2016 is currently a more advanced wind power installation ship, equipped with a 1,500 ton crane, a speed of more than 13 knots, and can install fan components in wind fields with water depths of more than 65 meters. At present, there are 14 third-generation wind power installation ships abroad, with a lifting capacity of more than 800 tons. Since 2011, relevant domestic design and construction enterprises have independently researched and developed the second and third generation wind power installation ships. At present, China has made great progress in design and construction technology, and the supporting capacity of special equipment has been greatly enhanced. A number of wind power installation ships have been independently designed and built, with a maximum lifting capacity of 2500 tons. However, there are fewer third-generation ships with rack and pinion lifting and self-propelled capability.

Deep blue

Common technological breakthroughs are urgently needed

Large offshore engineering ships are also known as offshore construction equipment, or more precisely, major engineering equipment floating on the sea. Due to the combination of hull and construction equipment and the extension of working waters to the deep sea, higher requirements are put forward for the survivability and working ability of large offshore engineering ships.

For construction equipment, because it is installed on the ship, it is affected by the movement of the ship. The high frequency movement of the ship on the wave, such as rolling, pitching and swinging motion, will produce a large additional load on the construction equipment, will produce forced vibration, so that the safety of the operation is threatened, or even can not work. Equipment that can operate safely and efficiently on land, applied to large engineering ships at sea, must consider the impact of additional loads when designing, and become non-standard equipment that must be specially designed.

The low-frequency motion of ship such as rolling, pitching and yawing and the increase of water depth will have a great influence on the ship's operation positioning and positioning. For large engineering ships operating in the deep sea, setting up reliable positioning, positioning and shifting systems has become an indispensable major technical measure, especially the dynamic positioning system, which can maintain a certain ship position, heading or make the ship move according to the predetermined trajectory by using its own propulsion system. Its position control accuracy is high, its flexibility is good, and the cost does not increase with the increase of the water depth. It has had a significant impact on promoting the progress of large engineering ships at sea. The dynamic positioning system is usually composed of four subsystems: environment and position reference system, propulsion system, power system and control system. The design and manufacture technology of dynamic positioning system has become the core technology in the design and manufacture of large offshore engineering ships.

For large offshore engineering ships, due to the improvement of operational capacity, especially the wide application of dynamic positioning system, the power supply capacity of large engineering ships is much larger than that of transport ships of the same scale, and even reaches more than 3 times. In the past 20 years, due to the mature development of AC frequency converter, electric drive has been widely used in large offshore engineering ships. Therefore, it has become an inevitable trend to build high-power power stations and carry out integrated energy management on large offshore engineering ships. In large engineering ships at sea, the dynamic positioning system and the automatic control of various operations involve the cooperation and coordination of multiple subsystems and equipment, involving the sharing and transmission of state parameters, and including the collection of external information and the necessary judgment and calculation, all of which can only be completed by computer automated network system. It has become one of the core technologies in the design of large offshore engineering ships to make comprehensive management of high-power stations and optimize the energy allocation of large offshore engineering ships under multiple working conditions by using computer network system.