Abstract
The audible signal (20 Hz to 20 kHz) generated during the operation of a dry-type reactor is one of the key features to evaluate its operation state. However, at present, the time/frequency domain features of the audible signal under typical insulation defects are not clear, which makes it difficult to effectively carry out the fault diagnosis of the dry-type reactor based on audible signals. Based on this, the audible signal features under typical insulation defect discharge of the dry-type reactor are studied in this paper. Three typical insulation defect discharge models (metal protrusion defect, pollution defect, and metal foreign bodies defect) are simulated; then, the discharge acoustic signals are collected under the voltage of 8 kV. Analysis of acoustic signal features shows that the acoustic signal of metal protrusion defect discharge occurs in the positive half cycle of power frequency with the cycle of 20 ms. Both pollution defect discharge and metal foreign bodies defect discharge show intermittent discharge; during the discharge, the discharge acoustic signal of pollution defect has features similar to that of metal protrusion defect, while the discharge of metal foreign bodies defect shows randomness with a larger amplitude of discharge acoustic signal (up to 110 dB). Based on the frequency domain feature vectors’ extraction, it is found that the odd harmonic component of the metal protrusion defect discharge acoustic signal accounts for more than twice the even-order harmonic, and the high-frequency energy (12.5–25 kHz) is the main component. The discharge acoustic signal of the metal foreign bodies defect is mainly low-frequency energy, and the high-frequency energy proportion of pollution defect discharge acoustic signal is similar to that of low-frequency energy. In addition, the variance of high-frequency energy ratio (Rhf) of the metal foreign bodies defect discharge acoustic signal is 5.25 and 21 times that of the metal protrusion defect and pollution defect. This study provides some technical support for further detection and assessment of the operation state of the dry-type reactor based on audible signals.
Highlights
As an important piece of power regulation equipment in a substation, a dry-type reactor has the functions of improving line voltage distribution, limiting short-circuit current, filtering, and so on.1–3 it is of great significance to improve the reliability by online monitoring of the dry-type reactor operation state and insulation fault diagnosis.4,5At present, the main methods used for fault detection of a drytype reactor at home and abroad include the vibration detection method6 and the optical imaging method.7,8In practical applications, according to the installation method, there are two types of vibration sensors for vibration detection: contact and non-contact
Based on the frequency domain feature vectors’ extraction, it is found that the odd harmonic component of the metal protrusion defect discharge acoustic signal accounts for more than twice the even-order harmonic, and the high-frequency energy (12.5–25 kHz) is the main component
The acoustic signal and pulse current signal were periodic, as shown in Fig. 9, and the discharge occurs in the positive half cycle of power frequency
Summary
As an important piece of power regulation equipment in a substation, a dry-type reactor has the functions of improving line voltage distribution, limiting short-circuit current, filtering, and so on. it is of great significance to improve the reliability by online monitoring of the dry-type reactor operation state and insulation fault diagnosis.. Contact vibration sensors need to be installed on the tested power equipment, such as piezoelectric and capacitive vibration sensors These sensors will be interfered by the strong electromagnetic field and surface discharge generated by the drytype reactor. The other is the non-contact vibration sensor, such as an optical vibration sensor This kind of sensor does not need to be installed on the tested equipment, but the cost is high and there is no positioning function. The authors of Ref. 11 designed a set of acoustic source location system based on beamforming technology, which can effectively locate the defects of the abnormal sound dry-type reactor, and confirmed the effectiveness of dry-type reactor defect detection technology based on audible signals At this stage, the research on fault diagnosis of the dry-type reactor mainly focuses on the detection of mechanical fault, inter-turn insulation fault, overheating, and interturn short/open circuit.. This study provides some technical support for further detection and assessment of operation state of the dry-type reactor based on audible signals
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