Abstract
Ultra-high-frequency (UHF) partial discharge (PD) online monitoring is an effective way to inspect potential faults and insulation defects in power transformers. The construction of UHF PD online monitoring system is a challenge because of the high-frequency and wide-frequency band of the UHF PD signal. This paper presents a novel, intelligent sensor for UHF PD online monitoring based on a new method, namely a level scanning method. The intelligent sensor can directly acquire the statistical characteristic quantities and is characterized by low cost, few data to output and transmit, Ethernet functionality, and small size for easy installation. The prototype of an intelligent sensor was made. Actual UHF PD experiments with three typical artificial defect models of power transformers were carried out in a laboratory, and the waveform recording method and intelligent sensor proposed were simultaneously used for UHF PD measurement for comparison. The results show that the proposed intelligent sensor is qualified for the UHF PD online monitoring of power transformers. Additionally, three methods to improve the performance of intelligent sensors were proposed according to the principle of the level scanning method.
Highlights
Power transformers are key equipment in power systems
A novel, intelligent senor for UHF Partial discharge (PD) online monitoring of power transformers based on the proposed level scanning method is introduced
The proposed intelligent sensor accurately acquires and directly outputs statistical characteristic quantities of UHF PD signals containing the distribution of magnitude and number of discharges in power frequency phase intervals without data post-processing, which avoids the error caused by signal delays and achieves low storage and fast real-time commutation for its small data quantity
Summary
Power transformers are key equipment in power systems. Faults and insulation defects may happen under electrical, thermal, and mechanical stress with the increase in operation time. PD is generally a transient phenomenon accompanied by physical and chemical phenomena, such as electrical pulse, electromagnetic wave, ultrasonic signal, mechanical vibration, and light and gas components, which can be detected by corresponding sensors [9,10,11,12,13,14,15,16] Among those methods, the ultra-high-frequency (UHF) PD detection method becomes an international, advanced research hotspot because of its advantages such as high sensitivity, strong anti-interference ability, high reliability, and ability to recognize and locate discharge sources [17,18,19,20,21,22]. There are several high-performance high-speed data acquisition cards and digital oscilloscopes satisfying the requirement, but they are not suitable for the online
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