Distributed optical fiber sensing for metal particle defect detection in GIS via frequency-swept interferometry

Area of Science:

• Electrical Engineering
• Materials Science
• Optoelectronics

Background:

• Conventional metal particle defect detection in gas-insulated switchgear (GIS) using piezoelectric (PZT) sensors is insufficient for distributed monitoring.
• Interferometric optical fiber sensors offer high sensitivity for GIS partial discharge detection but are typically limited to single-point measurements.

Purpose of the Study:

• To develop a multiplexing method for optical fiber acoustic emission sensors for distributed GIS monitoring.
• To overcome the single-point limitation of existing interferometric optical fiber sensors.

Main Methods:

• A multiplexing method for optical fiber acoustic emission sensors was proposed using optical frequency-scanning in a Michelson interferometric configuration.
• High-frequency carriers were introduced via optical frequency modulation, and channels were separated using bandpass filtering for frequency-division multiplexing.
• A single demodulation system was utilized to support multiple sensors.

Main Results:

• The proposed system successfully preserved the high sensitivity of single-point interferometric sensors while enabling multiplexed sensing.
• Experiments conducted on a 126 kV GIS with four sensing units demonstrated effective detection of discharge signals.
• The system could accurately identify the defective cavity within the GIS.

Conclusions:

• The developed optical fiber sensor system offers a promising solution for distributed condition monitoring of GIS.
• This frequency-division multiplexing approach enhances the capability of optical fiber sensors for power equipment safety.
• The method provides a practical approach for real-time, multi-point monitoring of critical infrastructure.