S. Hajiaghasi, K. Abbaszadeh, A. Salemnia,
Volume 15, Issue 1 (March 2019)
Abstract
Interturn fault detection is a challenging issue in power transformer protection. In this paper, interturn faults of distribution transformer are studied and a new online detection method based on vibration analysis is proposed. Transformer electromagnetic forces are analyzed by time stepping finite element (TSFE) modeling of interturn fault. Since the vibration associated with inter-turn faults is caused by electromagnetic forces, axial and radial electromagnetic forces for various interturn faults are studied. Transformer winding vibration under interturn faults is studied through an equivalent mathematical model combined with electromagnetic force analysis. The results show that it is feasible to predict the interturn winding faults of transformer windings with the transformer vibration analysis method. Simulation and experimentation studies are carried out on 20/0.4 kV, 50 kVA distribution transformer. The results confirm the effectiveness of the proposed method.
S. Hajiaghasi, Z. Rafiee, A. Salemnia, T. Soleymani Aghdam,
Volume 15, Issue 3 (September 2019)
Abstract
Since the insulators of transmission lines are exposed to different environmental conditions, it is important task to study insulators performance under different conditions. In this paper, silicone rubber insulators performance under different environmental conditions including rainy, icy, salt and cement are proposed and exactly is studied. Electric fields (E-fields) and voltage distributions along the insulator under various conditions have been evaluated. Moreover, the corona rings effects on insulator performance under these conditions have been presented. A 230 kV silicone rubber insulator is selected, modeled and simulated with finite element method (FEM) using the COMSOL software. The simulation is repeated for different environmental conditions and efficiency of corona ring for each scenario is evaluated. The results indicate that environmental conditions have a significant effect on the insulator performance and the corona ring somewhat alleviate the adverse effect of environmental conditions on the insulator performance.
