Abstract
The winding is the core component of a transformer, and the technology used to diagnose its current state directly affects the operation and maintenance of the transformer. The mechanical vibration characteristics of a dry-type transformer winding are studied in this paper. A short-circuit test was performed on an SCB10-1000/10 dry-type transformer, and the vibration signal at the surface was measured. Based on actual experimental conditions, a vibration-simulation model of the transformer was established using COMSOL Multiphysics software. A multiphysics coupling simulation of the circuit, magnetic field, and solid mechanics of the transformer was performed on this model. The simulation results were compared with measured data to verify the validity of the simulation model. The simulation model for a transformer operating under normal conditions was then used to develop simulation models of transformer-winding looseness, winding deformation, and winding-insulation failure, and the winding fault vibration characteristics were analyzed. The results provide a basis for detecting and analyzing the mechanical state of transformer windings.
Highlights
The safety and reliability of power transformers, which are the core pieces of equipment in a power grid, are important for the reliable operation of the entire power grid [1]
Equation (5) shows that the magnitude of the electric force on the transformer winding is proportional to the square of the load current flowing through the transformer winding, and the fundamental frequency of the vibration signal is twice the power frequency of the power grid
Changes in the mechanical state of the windings were reflected in their vibration signals
Summary
The safety and reliability of power transformers, which are the core pieces of equipment in a power grid, are important for the reliable operation of the entire power grid [1]. The frequency-response method is blackout detection, while the vibration-detection method is live detection [21,22] It can continuously monitor transformer-winding deformation and reflect the decline trend of transformer short-circuit resistance after repeated short-circuit shocks, which reduces the difficulty of online monitoring and fault diagnosis of the power transformer. Because the vibration of the transformer is a complicated process, the interaction between the magnetic field and the load current, as well as between the magnetostriction of the silicon steel sheet and the structural change in the transformer, produce changes in the vibration signal in both the time and frequency domains, increasing the difficulty in fault monitoring and diagnosis. The model utilizes multiphysical field-coupling simulation of the electromagnetic solid mechanics of dry transformer windings, which can provide a new basis for the state simulation and fault diagnosis of transformer windings
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