Optical Sensor for Monitoring Leakage Current and Weather Conditions in a 500-kV Transmission Line

Area of Science:

• Electrical Engineering
• Materials Science
• Environmental Monitoring

Background:

• Surface contamination and environmental variables significantly impact insulator leakage current (LC), a key online monitoring parameter.
• The specific influence of weather conditions like temperature, humidity, and dew point on LC requires deeper investigation.

Purpose of the Study:

• To investigate the impact of weather conditions on insulator leakage current using online meteorological and LC data.
• To establish a robust, reliable, and repetitive monitoring system for insulator status assessment.

Main Methods:

• Continuous three-year online monitoring of LC using optical fiber sensors on 500-kV insulator strings.
• Simultaneous acquisition of meteorological data, including temperature, air humidity, and dew point.
• Analysis of LC patterns in relation to varying weather conditions and identification of high-frequency pulses.

Main Results:

• Leakage currents exhibit distinct patterns correlated with specific weather conditions.
• Higher LC measurements were observed due to iron oxide powder contamination, forming a conductive layer independent of humidity.
• Partial discharge surges were identified as occurring when local temperature reaches the dew point, not solely due to high humidity.

Conclusions:

• The monitored LC serves as a crucial indicator for potential flashovers, facilitating predictive maintenance planning for transmission line insulators.
• The developed monitoring system demonstrates robustness, reliability, and repeatability over an extended period.
• Understanding the precise relationship between temperature, dew point, and partial discharge is vital for accurate insulator performance assessment.