Development of Intensity Modulated Optical Fiber Based Partial Discharge Sensor for High Voltage Power Apparatus

Partial discharge (PD) monitoring presently emerged as an effective tool for condition monitoring of high voltage power apparatus. For high-voltage (HV) applications, fiber optic-based sensing has several advantages over conventional sensors requiring an electrical connection. Many fiber optic-based sensors are recently being proposed utilizing fiber Bragg grating, Sagnac effect, and interferometric principal for the PD monitoring of HV power apparatus that detects the acoustic wave generated from the occurrence of PD. This article presents an intensity-modulated fiber optic sensing principle that provides a more simplistic approach toward acoustic wave detection, as it does not require any specialized light source and detector. The PD is a stochastic natural phenomenon, and monitoring of PD demands high bandwidth in the high-frequency region so that low-frequency machinery noises are discarded. In this work, a fixed-fixed beam type structure that approximately resembles the characteristics of a bandpass filter has been designed from the first principal model equations. Then, an optical fiber-based secondary sensing element is used to convert the beam vibration into a light intensity that can be transmitted to monitoring stations at a long distance from the HV apparatus. The simulation-based study and its experimental verification reveal that the sensor can provide the required sensitivity and bandwidth in the high-frequency region for monitoring PD inside the HV power apparatus. Therefore, the proposed advanced PD sensor can be utilized for condition monitoring of electrical insulation.