微分有限元海缆磁异常探测方法研究

Research on Magnetic Anomaly Detection for Submarine Cables Based on Differential Finite Element Method

摘要:

海缆在长久的电力信息输送过程中，损坏故障等突发事故经常发生，研究海缆在地磁背景下环境周围产生磁异常扰动信号，确定海底海缆轨迹和埋设深度，能够在突发状况之后迅速针对该区域内的海缆进行定位，及时对海缆进行维修。基于微元磁偶极子有限元仿真建立海缆磁场模型，探究了检测距离（D_CPA）、海缆长度（L）、背景磁场对海缆磁异常特性的影响规律。通过研究可知：D_CPA<L 时衰减指数约为–2，3L>D_CPA>L 时衰减指数约为–2.8，D_CPA>3L 时衰减指数约为–3；D_CPA 固定时，海缆磁异常随长度明显增加到一定程度会趋向稳定，信号发生畸变；背景磁场分量改变不仅可能改变海缆磁异常信号的强度，还可能改变其信号波形特征。

关键词:海缆;磁异常探测;磁偶极子模型;微元法

Abstract:

In the process of long-term power information transmission of submarine cables，sudden accidents such as damage and failure often occur. By studying the magnetic abnormal disturbance signals generated by submarine cables in geomagnetic background，the trajectory and buried depth of submarine cables can be determined，and the submarine cables can be quickly located in the area after the sudden situation，and the submarine cables can be repaired in time. The magnetic field model of the submarine cable is established based on the finite element simulation of microelement magnetic dipole，and the influence of detection distance（D_CPA），cable length （L）and background magnetic field on the magnetic anomaly characteristics of the submarine cable is explored. It can be seen from the study that when D_CPA <L，3L >D_CPA >L，D_CPA >3L，the attenuation index is about –2，–2.8，–3 respectively. When D_CPA is fixed，the cable magnetic anomaly tends to be stable with the increase of the cable length to a certain extent，and the signal distorts. The change of the background magnetic field component may not only change the strength of magnetic anomaly signal of the submarine cable，but also change the signal waveform characteristics.

Key words:submarine cables;magnetic anomaly detection;magnetic dipole model;microelement method