Study On Quench Simulation And Detection Technology Of A Saddle Superconducting Coil

Superconductors have zero resistance effect at extremely low temperature,complete diamagnetism,excellent electromagnetic performance and low energy loss,and have broad development and application prospects in energy,transportation,medical and electrical fields.Superconducting magnet operates in extremely low temperature environment,with harsh conditions.Its critical state is affected by magnetic field,temperature and current.During the operation of the superconducting magnet,the superconducting magnet may break away from the superconducting state due to various disturbance factors such as electromagnetism,heat and force,which means quench occurs.If the superconducting magnet fails to be effectively protected after quench,it may cause the magnet to be in the state of overheating and overvoltage,degrade the performance of the magnet and even cause damage to the magnet,which may lead to significant economic losses.Therefore,quench protection is an important issue to ensure the safe and stable operation of magnets.The quench simulation provides an important guarantee for the quench protection,and the quench detection is the prerequisite for the quench protection.The quench simulation and quench detection research carried out in this paper is based on the research and development of cryogenic superconducting magnetic separation magnets,and the analysis of the electrothermal coupling of the magnets is carried out.The specific project is a saddle magnetic separation coil of a sewage treatment plant.It mainly includes the following research contents:First of all,a two-dimensional fine cable model and a homogenized cross-section model of the superconducting magnet are established by using COMSOL finite element software.The influence of quench-back is considered under the refined cable type.The effective application of quench-back is verified by software calculation.The highest hot spot temperature of the magnet is 95 K,and the highest voltage is between-300 V and-200 V.In the homogenization model,the longitudinal variation of the coil is ignored,and the transverse variation of the coil is considered.The evolution of the parameters of the magnet current,voltage,temperature,resistance and quench propagation speed is obtained.The maximum hot spot temperature is 52 K,which is in line with the expected results.The magnet can be effectively protected by using the self-protection method.Secondly,the three-dimensional model of the magnet is established by OPERA,and the quench characteristics of the superconducting magnet in the whole state are comprehensively analyzed.The influence of different parameter settings on the magnet is analyzed.By setting appropriate current parameters and quench protection scheme,the evolution of the parameters of the magnet current,voltage,temperature,resistance and quench propagation speed is obtained after software calculation.At 120 A current,the highest hot spot of the coil is 25 K,and the highest voltage of the coil is 6.5 V.The results are in line with expectations.The magnet can be effectively protected by using the self-protection method.Finally,according to the randomness of the quench process of the magnet,the voltage detection method is studied to detect the quench.The quench detection program based on voltage detection is written through the PLC system of Kearns,and the feasibility of the program is verified in the power-on experiment of 2 T CCT magnet.This program can be used as a basic control program to participate in the test of superconducting magnets.