Noise Filtration Technique for Partial Discharge Diagnosis on Instrument Transformer using Statistical Tools

Abstract

Partial Discharge (PD) detection is an important method to evaluate the insulation condition of an instrument transformer (IT). Well known method like dissolved gas analysis (DGA) test requires the IT to be tested offline with complicated procedures to extract and refill back the oil to the IT. Nevertheless, DGA has been used to confirm incipient problems detected with other testing methods. High frequency current transformer (HFCT) is an alternative technique as non-intrusive PD measurement, which can be done on in-service IT; however, the limitation of this measurement is that it is easily susceptible to interference and disturbance found in any substations which superposed or dominated with PD signal. Hence, a noise filtration technique is proposed for filtering interference and disturbance using statistical parameters.