A Sensor Concept for Direction-Selective Monitoring of Partial Discharges in Medium-Voltage Switchgears

Area of Science:

• Electrical Engineering
• Materials Science
• Power Systems

Background:

• Partial discharges (PD) are critical indicators of insulation health in electrical equipment.
• Offline PD testing is accurate but costly and labor-intensive, limiting its widespread use.
• Comprehensive PD monitoring is lacking in medium-voltage (MV) grids.

Purpose of the Study:

• To introduce a novel sensor concept, the Magnetic Flux Concentrator Sensor (MFCS), for detecting PD in MV switchgear and cables.
• To develop a method for direction-selective PD detection using MFCS in combination with High-Frequency Current Transformers (HFCTs).
• To evaluate the sensor concept and directional detection method theoretically and experimentally.

Main Methods:

• Development of an inductive sensor (MFCS) with a uniquely shaped ferrite core for enhanced magnetic saturation properties.
• Utilizing the MFCS's high sensitivity in the MHz frequency range.
• Combining MFCS with conventional HFCTs to achieve direction-selective PD detection.

Main Results:

• The MFCS demonstrates high sensitivity and improved magnetic saturation characteristics compared to traditional HFCTs.
• The proposed sensor is not saturated by typical MV power cable operating currents.
• Theoretical analysis and laboratory experiments validated the sensor concept and the directional PD detection method.

Conclusions:

• The MFCS is a promising technology for sensitive, non-invasive PD detection in MV power systems.
• The combination of MFCS and HFCT enables effective direction-selective PD localization.
• This approach facilitates permanent operational monitoring, enhancing electrical equipment reliability and grid safety.