Semi-Submersible Platform Positioning Under Propeller Faults
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Solution Overview
Problem
Semi-submersible offshore platforms face stability issues and disrupted resource extraction when propellers fail to generate the expected reaction force, affecting their ability to maintain a stable position amidst external environmental interference.
Innovation Solution
A dynamic positioning method and device that utilize a first and second torque detector, along with a preset number of propellers, to detect external force torque, calculate target thrust torque, and adjust propeller thrust to maintain stability, even when propellers are faulty, by recalculating thrust based on fault conditions and external torque using a thrust distribution model, dynamic positioning model, and virtual observer model.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If propellers are controlled to generate reaction force to offset external environmental interference, then the semi-submersible offshore platform can be maintained at a target position, but if propellers fail to generate expected reaction force, the stability of the platform and resource extraction are affected
Solution Approach 1:
The patent implements a feedback mechanism where the actual thrust torque of each propeller is detected by a second torque detector and compared with the target thrust torque. When deviations are detected indicating propeller faults, the system automatically recalculates target thrust torques for all propellers based on the fault conditions and external force torque, then redistributes the thrust to compensate for the faulty propeller, ensuring the platform maintains its position stability despite propeller failures
Solution Approach 2:
The patent dynamically adjusts the control strategy based on real-time propeller conditions. When propeller faults are detected, the system transitions from normal operation to fault-tolerant operation by recalculating thrust distribution in real-time. This dynamic adaptation allows the platform to maintain stability under varying operational conditions and fault scenarios
2Reliability
If propellers are controlled to generate reaction force to offset external environmental interference, then the semi-submersible offshore platform can be maintained at a target position, but the system complexity increases due to multiple torque detectors and control calculations
Solution Approach 1:
The first torque detector serves multiple functions: it detects external force torque acting on the platform during normal operation and also provides data for calculating target thrust torques when propeller faults occur. The second torque detector monitors actual thrust torque of each propeller for both fault detection and feedback control purposes. This multi-functionality reduces the need for separate dedicated sensors for each function, thereby managing system complexity while maintaining high reliability
Data Source
AI summary
Disclosed are a method, a device, equipment and a medium for dynamic positioning of a semi-submersible offshore platform. The method includes: acquiring a real-time position of the platform; if the real-time position is different from a preset position, detecting an external force torque by a first torque detector; calculating a first target thrust produced by each of propellers, controlling the propellers to produce forces according to a first target thrust torque, and detecting an actual thrust torque; obtaining a fault condition of each of the propellers if the actual thrust torque is different from the first target thrust torque, indicating that the propellers have faults; recalculating a thrust of each of the propellers, a second target thrust torque, according to the fault condition, the external force torque and the preset formula set; and controlling each of the propellers to generate the thrust according to a corresponding second target thrust torque.