Fiber-Optic Cable Exposure Detection for Offshore Wind Power Cables
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Solution Overview
Problem
Current methods for monitoring subsea power cables in offshore wind farms are inadequate for continuous, cost-effective detection of dynamic changes from buried to exposed states, particularly due to external forces like strong currents and fishing activities, which are challenging to observe directly and incur significant operational costs.
Innovation Solution
Utilizing distributed acoustic sensing (DAS) technology to monitor the dynamic strain of optical fibers within composite cables, employing Phase-sensitive OTDR (Φ-OTDR) for real-time detection of strain changes, enabling early anomaly detection and localization of exposed cable sections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional monitoring methods are used for subsea power cables, then direct visual observation is possible, but the cost and operational complexity increase significantly
Solution Approach 1:
The patent replaces traditional mechanical/visual inspection methods with optical fiber-based distributed acoustic sensing. The optical fiber embedded in the composite cable serves as a sensor that detects strain changes through phase-sensitive OTDR measurements, eliminating the need for complex mechanical monitoring equipment and enabling continuous, cost-effective monitoring of cable conditions from buried to exposed states
Solution Approach 2:
The optical fiber serves multiple functions: it acts as both the communication medium within the composite cable and the sensing element for detecting cable strain and exposure status. This multi-functionality eliminates the need for separate monitoring infrastructure, reducing system complexity while maintaining measurement precision
2Reliability
If physical inspection methods are used to detect cable damage, then direct observation of damage is achieved, but operational costs and downtime increase
Solution Approach 1:
The distributed acoustic sensing system enables early detection of cable exposure and potential damage before actual failure occurs. By continuously monitoring strain changes in the optical fiber, the system can detect when a cable transitions from buried to exposed state, allowing preventive maintenance actions to be taken before damage occurs, thus reducing operational downtime and costs
Solution Approach 2:
The patent implements continuous monitoring of cable conditions through the optical fiber sensor network. Unlike periodic physical inspections, the distributed sensing system provides uninterrupted real-time data on cable strain and exposure status, enabling timely detection of damage and reduction of operational downtime through immediate response
3Difficulty of detecting and measuring
If external force monitoring is implemented, then detection of currents and fishing activities is improved, but the difficulty of direct observation increases
Solution Approach 1:
The optical fiber acts as an intermediary sensing element that translates mechanical external forces (currents, fishing activities) into detectable optical phase changes. This intermediary approach enables indirect but accurate measurement of external forces without direct physical observation, reducing the difficulty of detection while maintaining awareness of cable vulnerability to these forces
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Provides continuous, cost-effective monitoring of subsea power cables, allowing for early detection of cable exposure and potential damage, reducing downtime and operational expenses through real-time strain analysis.
Implementation Method 1
detects dynamic strain of an optical fiber—oftentimes part of a composite cable with the power cable—the phase changes in Rayleigh backscattered light (Phase-sensitive OTDR, Φ-OTDR)
Data Source
AI summary
Disclosed are systems and methods employing distributed fiber optic sensing (DFOS)/distributed acoustic sensing (DAS) that continuously monitor the buried/exposed status of undersea power cables for offshore wind farms. Our DAS systems and methods continuously monitor dynamic conditions characterizing undersea power cables and advantageously detect dynamic strain of an optical fiber that may be part of a composite cable with the power cable. By measuring and monitoring these dynamic conditions, a change in status from buried to exposed is determined and service personnel deployed before damage occurs to the power cable.