A Proposed Intensity Modulated Optical Fiber Based Sensor for Partial Discharge Detection in High Voltage Power Transformer

Power transformer is recognized as the heart of the power system. Insulation failure is the prime cause behind the failure of transformers. Partial Discharge (PD) is considered as the best indicator of insulation deterioration. So PD detection successively helps to prevent impending failures in capital equipment like transformers. In this paper, an intensity-modulated, optical fiber-based, invasive PD sensor is presented. The proposed sensor is designed to detect the high-frequency acoustic waves generated due to PD activity inside the transformers. An elastic fixed-fixed beam structure with predefined dimensions is designed as the primary sensing element. The structure is made of suitably chosen material having high dielectric strength. The optical fiber sensor is pasted on the primary sensing element using epoxy adhesive. The intensity-modulated optical fiber sensor consists of a fiber-to-fiber coupling having a high coupling coefficient. The designed sensor assembly modulates the intensity of the light when the primary sensing element vibrates due to PD-generated acoustic waves. Therefore, such an arrangement can be a cost-effective alternative to the high-cost fiber Bragg grating analyzers(FBGA) or tunable laser-based conventional acoustic PD detection methods. The fundamental design equations and the simulated results obtained using Ansys engineering simulation software are presented in this paper. From the study, it is profoundly observed that the proposed sensor is a progressive and efficient alternative in the field of acoustic PD detection of power transformers.