As one of the most important main equipments of VSC-HVDC transmission system, the dry-type air core bridge arm reactor is connected in series on the bridge arm of the converter, which plays the role of restraining the circulating current between bridge arms and the fault current of bridge arm rising too fast during short circuit. It bears the role of AC and DC compound large current in service. When the bridge arm reactor operates, it produces strong AC and DC magnetic field, which has a certain impact on the surrounding environment and the occupational safety of personnel. Based on the technical parameters of a bridge arm reactor, the magnetic field simulation model of multi encapsulation about bridge arm reactor is established in this paper, and the DC and AC magnetic field simulation calculation of the bridge arm reactor is carried out  under four working conditions: rated working condition, DC temperature rise current working condition, 50Hz temperature rise current working condition and 100Hz rated current working condition. By comparing the simulation results with the magnetic field limiting value of industry standards, it is specified that the magnetic induction intensity under rated working condition and DC temperature rise current working condition shall not exceed the standard limit of DC magnetic field. Under 50Hz temperature rise current working condition, the power frequency magnetic induction intensity of 1.8m above the ground and 6.96m along the radial direction of bridge arm reactor is less than the occupational exposure limit of 1000 μT. It also defines the requirement for the safe activity distance of operation and maintenance personnel under the working condition of 100Hz rated current, and puts forward the recommended measures for setting a safe anti magnetic fence. The research results of this paper can provide technical guidance for the magnetic field protection of VSC-HVDC bridge arm reactor and staff.

bridge arm reactor, VSC-HVDC, magnetic field, DC, AC