# Measurement and Analysis on Magnetic Field Influence of Substation for Magnetic Shielding Device
## 1 Introduction  
A magnetic shielding device shields low-frequency and static magnetic fields through the flux shunt effect [1, 2, 3] of high permeability magnetic materials (such as permalloy), shields AC magnetic fields through the eddy current effect [4, 5] of high conductivity materials (such as aluminum and copper), and prevents external magnetic fields from entering its interior through shielding, thus, generating an extremely weak magnetic field environment inside. In the weak magnetic environment, many scholars carried out frontier work, such as measuring biological signals such as in the heart and brain [6, 7, 8], measuring geophysical research samples [9], measuring electric dipole moments [10], and researching high-precision magnetic measurement instruments, such as SERF atomic gyroscopes and magnetometers [11, 12]. As the internal magnetic field of a magnetic shielding device is very weak, the magnetic shielding device system is vulnerable to the interference of a strong external magnetic field. In order to achieve better shielding effect, a magnetic shielding device is usually equipped with an active compensation coil outside to provide active magnetic field shielding, the passive shielding layer needs demagnetization, and the internal experimental instruments need power supply. All the above need to be equipped with substations for power supply, which may affect the shielding performance of magnetic shielding devices. For the research of magnetic shielding devices, many scholars use active compensation coils to improve the uniformity of the residual magnetic field inside the magnetic shielding device [13, 14, 15]. [PERSON] et al. [16] reported a degaussing method for a magnetic shieldingdevice, which can shorten the degaussing time by 10 times, significantly reduce the residual magnetic field of magnetic shielding devices, and improve the uniformity. Therefore, it is of great significance to study the influence of the substation used by magnetic shielding devices on the surrounding magnetic field for the positioning and design of the magnetic shielding device. In view of the influence of substations and other electrical equipment on the environmental magnetic field, many scholars carried out relevant research work [17; 18; 19; 20]. Some scholars introduced finite element simulation into the analysis of electric and magnetic fields generated by substations: [PERSON] et al. [17] used the finite element method to analyze the power frequency magnetic field distribution characteristics of a typical 2 \(\times\) 80 MVA substation. The results showed that the maximum magnetic induction intensity of 15 m around the substation was less than 1.6 \(\upmu\)T. For the electromagnetic environment of a 500 kV substation, [PERSON] et al. [18] proposed a full-scale simulation model using boundary element method (BEM) to calculate the distribution of the electric and magnetic fields, and obtained the distribution of electric and magnetic fields in the substation. [PERSON] et al. [19] studied the extremely low frequency (ELF) magnetic field environment distribution of a 500 kV/ 275 kV gas-insulated substation by comparing the measurement results with the finite element method (FEM) calculation results. [PERSON] et al. [20] measured the influence of different units of a thermal power plant on the surrounding magnetic field and simulated it through ArcGIS software v. 10.7.1. The exposure effect is ranked according to the size of the magnetic field, but the actual measured value is higher than the simulation value, so the simulation method needs to be further improved. [PERSON] et al. [21] analyzed the solution method of electromagnetic field distribution in a 110 kV substation, and simulated it in ANSYS, solving the distribution of electric field and magnetic field. Three positions with different heights from the ground are selected for measurement, and the measurement results are compared with the simulation results with good consistency. [PERSON] et al.