Subsea Cable Burial State Detection via Load-Temperature Covariance
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Solution Overview
Problem
Current methods for monitoring the burial depth and state of subsea electrical power cables are expensive, time-consuming, and insufficiently frequent, exposing cables to damage and potentially disrupting marine ecosystems, as they require complex and costly surveys that do not account for rapid changes in burial depth.
Innovation Solution
A method employing distributed temperature sensing (DTS) and load data analysis to estimate the burial state of subsea power cables without thermal modeling, using covariance-related quantities derived from load and temperature data to detect exposure and changes in burial depth, enabling continuous monitoring with conventional DTS devices and a load sensor, without additional measurement devices or knowledge of thermal parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If annual or bi-annual surveys are used to monitor burial depth, then the monitoring process is simple and inexpensive, but the monitoring frequency is insufficient and cannot detect rapid changes in burial depth
Solution Approach 1:
The power cable itself serves as the temperature sensor through integrated optical fibers, eliminating the need for separate monitoring devices. The cable's own thermal response to load changes provides the measurement signal, allowing continuous high-frequency monitoring without complex external equipment.
Solution Approach 2:
The patent replaces mechanical survey methods (physical inspection) with optical-based distributed temperature sensing. By using optical fibers to measure temperature distribution along the cable and correlating it with load data, the system achieves continuous monitoring without mechanical intervention or complex survey equipment.
2Measurement precision
If complex thermal modeling and additional measurement devices are used, then measurement precision improves, but device complexity and cost increase
Solution Approach 1:
The patent extracts only the essential measurement signal (temperature distribution along the cable) needed to determine burial state, eliminating the need for complex thermal modeling. By using the natural thermal response of the cable to load changes and comparing it with reference measurements, the system achieves accurate burial depth detection with minimal processing.
Solution Approach 2:
The patent changes the measurement parameter from direct physical measurement of burial depth to indirect measurement through temperature distribution. By monitoring how temperature varies along the cable length in response to load changes, and comparing this pattern to reference patterns, the system determines burial state without directly measuring depth or requiring complex thermal models.
3Ease of manufacture
If conventional DTS devices with load data analysis are used, then monitoring cost decreases, but the ability to detect burial state changes without thermal modeling is improved
Solution Approach 1:
Instead of using thermal modeling to predict temperature from known burial conditions, the patent inverts the approach: it uses measured temperature distributions and load data to infer burial state. By analyzing the actual thermal response pattern and comparing it with reference patterns from known burial states, the system achieves accurate detection without requiring thermal models.
Solution Approach 2:
The patent implements a feedback mechanism where temperature measurements and load data are continuously analyzed to detect changes in burial state. By comparing current temperature patterns with reference patterns and detecting deviations, the system provides real-time feedback on burial depth changes, enabling timely detection and response to potential issues.
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
This approach allows for faster, more reliable monitoring of subsea power cables, detecting exposure and burial depth changes quickly and continuously, reducing the need for expensive equipment and surveys, and providing real-time feedback without requiring complex thermal modeling or ambient condition knowledge.
Implementation Method 1
employing distributed temperature sensing
Implementation Method 2
The processor is further configured to derive, for each location, from the load data samples and the temperature data samples, a location specific covariance related quantity related to a covariance or a correlation of a load, and/or temporal load change and/or a load related quantity on one hand and a temporal temperature change or temporal temperature change related quantity on the other hand
Data Source
AI summary
It is provided a method of estimating a burial state of a subsea electrical power cable (5), the method comprising: obtaining load data samples (4) pertaining to plural points in time (t) at one or more locations, the load data samples indicating an electrical load the power cable (5) is subjected to; obtaining temperature data samples (15, 16) pertaining to plural locations (x_i, i) along the power cable (5) and pertaining to the plural points in time; deriving, for each location (x_i), from the load data samples (4) and the temperature data samples (15, 16), a location specific covariance related quantity (C_i(Δt)) related to a covariance or a correlation of the load and a temporal temperature change; each covariance related quantity may be determined by multiplying the current at a particular point in time with the temperature change at a point shifted in time by Δt over an extended period of time, and for a plurality of different shifts Δt. The state of the power cable is estimated based on analyzing the derived covariance related quantities (C_i(Δt)), without the need to perform thermal modelling. The maximum of the temperature increase, and its time-shift with regard to the point in time with regard to the load data sampling point depends on the burial state.