Distributed Fibre Optic Sensor Fault Location in Power Cables
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Solution Overview
Problem
Detecting faults in power cables, particularly those leading to current discharges, is challenging due to the difficulty in locating partial discharges and catastrophic failures in long underwater or buried cables, which can result in costly and disruptive power outages.
Innovation Solution
A method using distributed fibre optic sensors with sensing optical fibres deployed along the power cable to monitor electrical parameters and detect faults by analysing measurement signals indicative of disturbances, such as acoustic impulses and temperature variations, within specific time windows to identify the location of faults.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional fault detection methods are used for power cables, then the detection process is simple, but the ability to locate faults accurately in long underwater or buried cables is poor
Solution Approach 1:
The patent introduces acoustic sensors as intermediary devices that detect acoustic waves generated by fault discharges in the cable. These sensors convert the acoustic energy into electrical signals that can be processed to determine fault location, thereby enabling accurate detection without directly interfering with the power transmission system.
Solution Approach 2:
The patent replaces traditional electrical testing methods with acoustic wave detection. Instead of using electrical signals to detect faults, the system uses acoustic sensors to detect mechanical vibrations and sound waves produced by partial discharges and catastrophic failures, enabling non-intrusive fault location.
2Reliability
If distributed fibre optic sensors are deployed along the power cable to monitor faults, then fault detection capability is improved, but the device complexity and installation difficulty increase
Solution Approach 1:
The patent utilizes optical fibres that serve dual purposes: their primary function for data communication and their secondary function as sensing elements for fault detection. The same optical fibre infrastructure used for communication is leveraged to detect acoustic waves and temperature changes, eliminating the need for separate dedicated sensing systems.
Solution Approach 2:
The optical fibre system monitors its own environmental conditions (acoustic waves, temperature) along its length without requiring external sensing devices. The fibre itself acts as the sensor, detecting changes in its physical environment caused by cable faults through intrinsic physical effects.
3Loss of time
If real-time monitoring of electrical parameters is implemented to detect faults, then response time to faults is reduced, but the energy consumption and system complexity increase
Solution Approach 1:
The monitoring system uses periodic pulsed laser signals to interrogate the optical fibre sensors rather than continuous monitoring. This periodic action reduces energy consumption while still providing timely fault detection, as the pulsed signals are sufficient to detect acoustic waves and temperature changes when faults occur.
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
Enables rapid and accurate location of faults, reducing downtime and maintenance costs by providing real-time detection and analysis of fault locations in power cables, even in inaccessible environments like underwater or urban settings.
Implementation Method 1
perform distributed fibre optic sensing based on coherent Rayleigh backscattering
Implementation Method 2
signals indicative of the extent of any temperature variations the longitudinal sensing portions of the sensing fibre
Data Source
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AI summary
This application relates to methods and apparatus for determining the location of a fault (204) in a power cable (100) of a power distribution network. The method involves monitoring at least one electrical parameter of the power distribution network to detect the occurrence of a fault in the power cable and determine at least one time window (twin) for the occurrence of the fault. The fault may be detected by detecting opening of a circuit breaker (205). The method involves analysing a first set of measurement signals is obtained by a distributed fibre optic sensor (302) having a sensing optical fibre (301) deployed along the path of the power cable. The first set of measurement signals comprise signals indicative of the extent of any disturbances on each of a plurality of longitudinal sensing portions of the sensing fibre over a known time period. The measurement signals are analysed based on said at least one time window for measurement signals (502) indicative of a fault in the power cable and the location of the fault in the power cable is identified based on the location of one or more longitudinal sensing portions of the sensing fibre giving rise to the measurement signals indicative of a fault in the power cable.