Research Of Quench Detection For 100 KA Superconducting Transformer In CRAFT

The Conductor Performance Research Platform is an important sub-unit of the superconducting magnet research system of Comprehensive Research Facility for Fusion Technology(CRAFT).he superconducting transformer is an important part of it.Its main function is to provide up to 100 kA test current for superconducting conductors.Once the transformer magnet quenches,the electric energy stored in the magnet will be converted into ohmic heat,which makes the temperature of the magnet rise rapidly,which not only causes damage to the superconducting transformer itself,but also affects the operation safety of the whole device.Therefore,designing a safe and reliable quench detection system is an important research content of the superconducting transformer.Based on the investigation of quench detection methods related to superconducting transformers at home and abroad,this paper deeply studies the operation characteristics of the superconducting transformer,the quench characteristics of magnets and the quench process of multi-coupled superconducting magnets.A quench detection system for all-round protection transformer is designed and the detection objects include primary coil,secondary coil and current lead.The main work of this paper is as follows.1.Based on the analysis of the operation characteristics of the superconducting transformer,according to the structural characteristics of the magnet and the electromagnetic parameters,the three-dimensional quench propagation model and the onedimensional quench propagation model are established for the primary coil and the secondary coil of the transformer,and the three-dimensional quench propagation process is analyzed.The quench characteristics of the superconducting transformer and the physical process of magnet quench are studied by quench simulation.2.The influence of AC magnet on the quench detection of background field magnet in various operating modes are studied and analyzed,especially the influence of quench of the superconducting transformer on the stability of background field quench detection system.3.On the basis of simulation analysis,according to the structural characteristics of the magnet,the quench detection methods such as balanced bridge detection,terminal voltage detection,slope detection and optical fiber detection are applied to the transformer magnets.The quench signal processing and control system is designed,including isolation system,quench compensation system,quench discrimination system and data acquisition system.