Application Of Beidou/GPS Dual-mode Positioning System In Self-elevating Wind Power Construction Ship

In marine engineering project,the construction area is generally far from the coastline.The traditional landmark positioning and total station observation method can not meet the needs of current engineering constru ction because of shortcomings such as short communication distance and poor real-time performance.At present,Beidou positioning system with independent intellectual property rights in China has the ability to provide location services to the world.It ca n also work completely independently of the GPS system.In the future,Beidou Positioning Technology will be widely used in offshore engineering.Offshore wind power has been developed in recent years.Offshore wind farms are generally far away from the coastline.Construction operations are difficult.Construction operations require the use of professional wind power installation vessels to go to the open sea for construction.‘Fenghua' is a self-elevating wind power installation ship.The four legs of this ship are more than 60 meters above the deck surface.The high-rise pile legs are occluded to the receiver during the positioning process of the ship.Single GPS positioning system,under such conditions,is difficult to search for stars,and the number of observable stars is small.RTK solution speed is slow and the positioning effect is poor.This project has fully investigated the research status of satellite communication technology at home and abroad,common system architecture,applications and chara cteristics.Combined with the structural characteristics of "Fenghua",the working principle of differential positioning technology is analyzed in detail,and the key technology of ship positioning system is studied.We developed a construction positioning system based on Beidou/GPS dual-mode positioning technology,and analyzed the conversion relationship between WGS84 latitude and longitude coordinates and engineering coordinates in detail.And the mathematical model between the engineering coordinates and the hull coordinate system is established,the position of the ship in the local engineering coordinate system is calculated in real time,and the impact of the hull shaking on the positioning result is compensated in real time,It solves the problem of accuracy and real-time of engineering ship positioning innovatively,and can achieve positioning accuracy of centimeter level of ship.The construction positioning system developed by this project was put into use in Pinghai gulf Wind Farm and Dongtai Wind Farm.It can calculate the distance between the legs and the submarine cable in real time,and display the position of the hull in the engineering coordinate system in real time,as well as the relative position of the surrounding sea cable and fan cap.The positioning accuracy meets the requirements of construction specifications,and the accuracy,stability and reliability of the system are fully demonstrated.This project has formed a complete set of technology combining positioning technology and contr ol system,and extends the application of Beidou positioning technology to the offshore construction field.Its research results have good promotion and application value in marine engineering.