Ultra-high frequency antenna sensor with self identification and ambient noise reduction for partial discharge detection in open substations / S. M. Kayser Azam

S. M. , Kayser Azam (2024) Ultra-high frequency antenna sensor with self identification and ambient noise reduction for partial discharge detection in open substations / S. M. Kayser Azam. PhD thesis, Universiti Malaya.

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Abstract

The occurrence of partial discharge (PD) in high voltage (HV) insulation can lead to equipment failure and is detectable in the ultra-high frequency (UHF) range. UHF antennas are increasingly popular as PD sensors, but existing models face challenges in early PD signal detection, ambient noise reduction, and PD identification, especially in open substations. Current UHF sensors rely on expensive amplifiers and additional filters, making data processing error-prone and cumbersome. Identifying the exact PD-affected equipment early on has also been unresolved by recent RFID tag-assisted systems. This research introduces a novel standalone UHF antenna sensor that addresses these challenges. Based on a planar monopole antenna (PMA), the sensor was developed systematically from this fundamental design. First, a preliminary investigation sensor (PIS) is created as a reference to characterize PD detection under various conditions. Next, a primary sensor (PS) is designed to enable early PD detection, forming the final identifying sensor (IDS) basis. The IDS follows a design hierarchy, incorporating a noise-cancelling sensor (NCS) with a novel notch element called a complementary intermingled resonator (CICR) to reduce ambient noise. A novel notch element concentration (NEC) mechanism is introduced to enable self-identification through multi-resonating bits. The IDS prototype reduces sensor size by over 35.35% and improves the average realized gain by more than 48.93% compared to existing UHF antenna sensors. It achieves high sensitivity at 271.10 dBi/m² and a Figure of Merit of 1.809 dB, higher than other antenna sensors. Operating within 0.78–1.38 GHz, the IDS targets the most PD-affected frequency range. Without additional filters, it reduces the in-band noise of GSM-900 during PD detection, lowering the noise floor to 2.5 mV. The IDS provides multi- resonating 6-bit identification codes with 1-bit noise reduction, outperforming RFID tags. Experimental results validate the IDS's standalone operation, demonstrating superior performance in early PD signal detection, ambient noise reduction, and PD event identification in open substations.

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