Investigation of Partial Discharge Due to Copper Spherical Particle in Power Transformer Under Various Oil Flow Models Using CFD

Power transformer is an important and costly device in electrical power system. Analysis of power transformer is useful to protect the device from different hazards. Mineral transformer oil acts as a coolant and part insulation in power transformers. Transformer cooling is ensured by non-directed or directed flow of oil inside the transformer. Transformer oil is found to consist of conducting particles moving along the flow path of transformer oil. Particles which are conductive in nature when come in contact with the disc, get stress formed on them and may lead to partial discharge (PD). Partial discharge due to particle is one of the grounds of failure of transformers. To find the behaviour of the particle, computational fluid dynamics (CFD) analysis using ANSYS software is performed. Analysis is carried out for high voltage (HV) winding of a 100 MVA power transformer. Path of movement of spherical particles made up of copper is simulated using CFD. Stress formed on each particle at the point of impact with transformer disc is calculated theoretically. This paper presents a detailed discussion on the impact of oil flow, velocity of oil and initial position of the particle at the bottom of transformer with regard to initiation of PD.