Study On Leakage Magnetic Field Of Superconducting Energy Storage Magnet With Multi-Spiral Tube Composite Structure

With the continuous development of electric power system,superconducting Magnetic Energy Storage(SMES)has gradually entered the daily life of people.Connecting SMES to the power system can not only improve the stability of the power system,improve the quality of power,provide system backup capacity,conduct energy management of distributed power system,but also has high energy storage efficiency,simple technology,no mechanical rotation loss,fast response and other advantages by comparing with other energy storage methods.As the core components of SMES,superconducting energy storage magnets play the role of receiving,storing and rapidly distributing electromagnetic energy.Therefore,more and more researchers study it in depth.When SMES stores a large amount of energy,superconducting energy storage magnets may produce a strong leakage magnetic field during the operation process.It directly affects the surrounding sensitive electronic devices and the working environment of the staff,and causes electromagnetic interference or damage to electronic equipment,posing threats to the safety of surrounding staffs.Therefore,it is significantly important to reduce the leakage magnetic field generated by SMES during the operation process on the surrounding environment.The dissertation firstly expounds the background and significance of research on reducing the leakage magnetic field generated by SMES during the operation process,gives a brief introduction to the working principle and components of SMES,and summarizes the development of SMES and the current research situation at home and abroad.Secondly,the dissertation introduces the theoretical basis of electromagnetic field and the finite element analysis method which are used on analyzing leakage magnetic field,and introduces the finite element analysis software COMSOL Multiphysics which is used for modeling and simulating on superconducting energy storage magnet.The dissertation also introduces related knowledge of genetic algorithm,sequential quadratic programming algorithm and genetic sequence quadratic programming method by combining advantages of two algorithms.The classification and selection of superconducting materials are introduced again.Taking economy as the objective,the parameters of single-screw superconducting energy storage magnet are optimized based on the genetic sequence quadratic programming method.COMSOL is used for modeling and simulation analysis to extract the maximum magnetic field strength at a distance of two meters away from the magnet center.Finally,the shielding principle of leakage magnetic field of superconducting energy storage magnets is analyzed.Based on the method of changing magnets structure to reduce the leakage magnetic field,the dissertation designs five kinds of multi-screw pipe compound structure superconducting energy storage magnets as improvement schemes.And then calculates the inductance value,respectively.Taking economy as the objective,the parameters of magnets are optimized based on the genetic sequence quadratic programming method.COMSOL is used to model building and simulation analysis,and extracts simulation data for comparative analysis.Making comparative analysis first in terms of the size of the leakage magnetic field,the distribution of the leakage magnetic field and economy,then the conclusion is drawn.The results show that all the five schemes can reduce the leakage magnetic field to some extent,of which the shielding effect of scheme 5 is the best.Scheme 2 has therapeutic shielding effects,and consumes the least superconducting material when the strong magnetic flux leakage is distributed at both ends of the magnet.