Background

Subsea power cable failures in offshore wind farms result in significant financial losses. One common failure mode is submarine power cable bending.

Objective

The primary objective of this study is to validate two analytical models using strain readings obtained from a novel 3-point bending setup designed for power cable specimens. The setup incorporates two types of optical fiber sensors for simultaneous strain measurement.

Methods

A 3-point bending setup is constructed, integrating optical fiber sensors installed on the embedded fiber optic cable within the submarine power cable. One set of sensors is fixed to the fiber optic cable sheath, while a second set consists of loose tube fibers that are inside the fiber optic cable. The strain readings of the fixed sensors are compared to two analytical models. The first analytical model assumes a constant power cable curvature, while the second model considers variable curvature.

Results

The analytical models both predict nearly flat strain profiles and are in line with each other. The strain data, however, approaches zero strain away from the cable center. Model assumptions such as perfect sensor positioning and zero slip of the fiber optic cable cause this discrepancy. The results of the constant curvature model agree well with strain averages of the fixed sensors around the central region of the power cable, and both scale linearly with amplitude. Finally, the strain readings from the loose tube fibers demonstrate high reproducibility, facilitating the development of a calibration curve for estimating power cable curvature.

Conclusions

The analytical models surpass existing models by providing good agreement with the measured strain around the cable center. Moreover, the highly reproducible strain readings from the loose tube fibers allow estimating power cable curvature.

中文翻译：

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评估使用固定松管光纤应变传感器的海上电力电缆弯曲分析方程的有效性

背景

海上风电场的海底电缆故障会导致重大的财务损失。一种常见的故障模式是海底电力电缆弯曲。

客观的

本研究的主要目的是使用从专为电力电缆样本设计的新型三点弯曲装置获得的应变读数来验证两个分析模型。该装置包含两种类型的光纤传感器，用于同时进行应变测量。

方法

构建了一个三点弯曲装置，集成了安装在海底电力电缆内嵌入式光缆上的光纤传感器。一组传感器固定在光缆护套上，而第二组传感器由光缆内部的松管光纤组成。将固定传感器的应变读数与两个分析模型进行比较。第一个分析模型假设功率电缆曲率恒定，而第二个模型考虑可变曲率。

结果

分析模型都预测几乎平坦的应变分布并且彼此一致。然而，远离电缆中心的应变数据接近零应变。模型假设（例如完美的传感器定位和光纤电缆的零滑移）会导致这种差异。恒定曲率模型的结果与电力电缆中心区域周围固定传感器的应变平均值非常吻合，并且两者均随振幅线性缩放。最后，松管光纤的应变读数具有很高的再现性，有助于开发用于估计电力电缆曲率的校准曲线。

结论

分析模型与电缆中心周围测量的应变具有良好的一致性，从而超越了现有模型。此外，松管光纤的高度可重复的应变读数可以估计电力电缆的曲率。