Acoustic signal is the key characteristic parameters for identifying partial discharges (PD) in power transformers. To address the limitations of conventional PD monitoring techniques, such as weak anti-electromagnetic interference and inability to achieve internal deployment, a fiber Bragg grating (FBG) with a frequency range of 5-60 kHz covering audible sound and low-frequency ultrasound was designed in this paper. The sensor was employed to monitor acoustic signal during the discharge process between column-column electrodes in transformer oil, and the frequency domain gravity center and audible acoustic energy proportion of acoustic signal were extracted. Further, the prepared sensor was embedded within a full-scale transformer to verify its monitoring effectiveness for the internal discharge sound signals of transformer. The results show that the dominant frequency bands of the column-column electrode discharge acoustic signals in transformer oil are within the range 5-10 kHz and 46-60 kHz, and the frequency domain gravity center and the audible acoustic energy proportion of the acoustic signal show a trend of increasing first and then decreasing with discharge severity. The proposed FBG sensor can effectively monitor the discharge development in the ±400 kV converter transformer.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |