Electromagnetic-force calculation and fault diagnosis of shell transformer under inter-turn short circuit

Aiming at the electromagnetic distribution law, winding mechanical response characteristics, and degree diagnosis of inter-turn short circuit fault locations of shell-type transformers under inter-turn short circuits, the research idea of “simulation calculation-characteristic analysis-experimental verification” is adopted. Aiming at the characteristics of the new wrapped winding of the shell-type transformer, a three-dimensional finite element model of the inter-turn short circuit of the shell-type transformer winding is established to solve the short-circuit current and the leakage magnetic field. Based on multi-physical field coupling, a winding vibration model is constructed and the inter-turn short circuit and winding electromagnetic force and displacement are analyzed to determine the maximum displacement region. The relationship between the different short-circuit turns of the winding and the amplitude of the winding vibration acceleration was analyzed, and the inter-turn short-circuit fault displacement of the shell-type transformer was diagnosed. An inter-turn short-circuit experimental platform was built to measure the magnetic field leakage, vibration acceleration time domain, and frequency domain distribution of the shell-type transformer winding under different short-circuit turns and positions. The results showed that when the number of short-circuit turns reached 15 turns, the magnetic flux density of the fault winding increased by 404.4%, the vibration acceleration of the fault winding increased by 467.5%, and the correct rate of inter-turn short-circuit fault diagnosis was 96.16%, which provides theoretical support and engineering methods for the prediction and diagnosis of inter-turn short-circuit faults of shell-type transformers.