Localization for Dual Partial Discharge Sources in Transformer Oil Using Pressure-Balanced Fiber-Optic Ultrasonic...

Area of Science:

• Electrical Engineering
• Materials Science
• Acoustics

Background:

• Partial discharge (PD) is a critical factor in power transformer insulation degradation and failure.
• Accurate localization of dual PD sources is challenging due to limitations of existing sensors under high oil pressure and internal obstructions.
• Existing piezoelectric and F-P sensors struggle with sensitivity and accuracy in detecting dual PD sources deep within transformer oil tanks.

Purpose of the Study:

• To develop an optical fiber ultrasonic sensor with a pressure-balancing structure for detecting dual partial discharge (PD) sources in transformer oil.
• To overcome the limitations of oil pressure affecting sensor sensitivity and enable detection under high-voltage conditions.
• To create a dual PD detection system for accurate localization of complex fault types in power transformers.

Main Methods:

• Design and implementation of an optical fiber ultrasonic sensor featuring a pressure-balancing structure.
• Development of a dual PD detection system utilizing an array of these sensors.
• Application of a cross-positioning algorithm for the detection and localization of dual PD sources.
• Testing the system on a 35 kV single-phase transformer in various fault regions.

Main Results:

• The proposed sensor demonstrates good sensitivity and directional clarity in detecting dual PD sources, even under high oil pressure.
• The sensor array successfully detected and localized dual PD sources in oil and winding interturn faults without obstructions.
• The system effectively detected discharge waveforms from dual PD sources in obstructed regions, such as within transformer winding oil channels.
• The pressure-balancing structure adapts to oil pressure variations, enhancing sensor performance deep within the oil tank.

Conclusions:

• The optical fiber ultrasonic sensor with a pressure-balancing structure is effective for detecting dual PD sources in power transformers.
• This technology enhances the online monitoring capabilities for power transformers, improving operational reliability.
• The developed system provides a robust solution for accurate localization of complex dual PD faults, aiding in predictive maintenance.