Calculation of Transient Magnetic Field of DC Field during Bipolar Short Circuit of Flexible DC Converter Station

Hybrid DC circuit breaker used in higher voltage flexible HVDC project is the current development trend. With the increase of the breaking current level of the DC circuit breaker, the magnetic field interference intensity of the surrounding secondary equipment is gradually enhanced. In this paper, the DC field of DingHai converter station of Zhoushan flexible DC transmission project is taken as the simulation object. Considering the commutation process of DC breaker breaking large current, the transient magnetic field interference value of the secondary equipment in the DC field is calculated when the bipolar short circuit occurs on the DC side. The results show that when the DC circuit breaker breaks the 15 kA current, the maximum value of the magnetic field interference of the secondary equipment near the positive and negative DC circuit breakers in the DC field are 700 A/m and 382 A/m, respectively. The peak value of the magnetic field interference can be included in the test level proposed in the electromagnetic compatibility standard "Test and Measurement Technology: Pulse Magnetic Field Immunity Test", but the duration time of the pulsed magnetic field waveform to be evaluated is recommended to be maintained at 3 ms.