Performance evaluation of noise reduction method during on-line monitoring of MV switchgear for PD measurements by non-intrusive sensors

• Published in: International journal of electrical power & energy systems 2015-01, Vol.64, p.596-607
• Main Authors: Hussain, Ghulam Amjad, Shafiq, Muhammad, Kumpulainen, Lauri, Mahmood, Farhan, Lehtonen, Matti
• Format: Article
• Language: English
• Subjects: Arcing; D-dot sensor; Discrete Wavelet Transform (DWT); High frequencies; Inclusions; Insulation; Monitoring; Non-intrusive sensor; Online; Panels; Partial Discharge (PD); Sensors; Switchgear
• ISSN: 0142-0615; 1879-3517
• DOI: 10.1016/j.ijepes.2014.07.057

•Novel application of a new sensor for PD measurements in air insulated switchgear.•Description of different noise, causing interference during online monitoring.•De-noising of measured PD signals through Discrete Wavelet Transform (DWT).•Performance evaluation of the de-noising method.•Self adaptive de-noising approach through flow chart. Partial Discharge (PD) measurement is a globally accepted method for insulation diagnosis of electrical assets. The consequences of insulation breakdown are well known. The trend is to move from conventional offline testing to online monitoring for insulation life prediction, which results in the inclusion of high frequency noise in the captured signals. Therefore de-noising is of paramount importance in online monitoring to obtain useful information from the signal. In this research, a 20kV switchgear panel has been subjected to PD faults in the laboratory and measurements have been carried out by using different non-intrusive sensors including a novel sensor, the D-dot sensor and recorded by a high frequency oscilloscope. The measured results show the effective applicability of sensors for switchgear. The Discrete Wavelet Transform (DWT) has been used to de-noise PD signals in this paper. Time domain and frequency domain comparison of original and de-noised PD signals reveals the significance of this technique for online monitoring of Medium Voltage (MV) switchgear. Finally, an adaptive online de-noising concept, based on automatic de-noising is also proposed in this paper.