Research and Experiments on an External Miniaturized VFTO Measurement System

Area of Science:

• Electrical Engineering
• Power Systems
• Electromagnetics

Background:

• Operations of disconnect switches and circuit breakers in gas insulated switchgear (GIS) can generate very fast transient overvoltages (VFTO).
• VFTO poses a risk of damage to substation equipment, necessitating accurate detection methods.
• Existing VFTO sensors are often large, difficult to install, and require modifications to GIS infrastructure.

Purpose of the Study:

• To propose and validate a miniaturized measurement system for detecting VFTO in GIS.
• To overcome the limitations of conventional VFTO sensors regarding size, installation complexity, and system modification.

Main Methods:

• Development of a miniaturized measurement system incorporating a capacitive voltage divider and a differentiating-integrating circuit.
• Design of a specialized sensor structure and optimization of circuit component arrangement to enhance system bandwidth.
• Conducting frequency-domain, time-domain, and voltage divider calibration experiments.
• Performing comparative analysis with an existing internal VFTO sensor.
• Field testing of the system in a 500 kV GIS substation.

Main Results:

• The proposed system demonstrated increased bandwidth through specialized sensor structure and optimized circuit design.
• Calibration experiments confirmed the system's accuracy in frequency, time, and voltage division.
• Field measurements in a 500 kV GIS substation successfully captured VFTO events.
• Measured waveforms in both time and frequency domains aligned with IEC 60,071 standards for VFTO.

Conclusions:

• The developed miniaturized measurement system effectively meets the requirements for VFTO detection.
• The system is suitable for practical application in real-world VFTO measurements within GIS substations.
• This innovation offers a more accessible and less intrusive solution for monitoring VFTO phenomena.