Abstract: After a busbar fault in the low-frequency transmission system of offshore wind power takes place,the equivalent potential and impedance of the converter-type power source are no longer considered constant like traditional power grids due to the switching and adjustment process of control.The paper theoretically analyzes the adaptability of busbar current differential protection and clarifies the impact modes of fault control strategies on the sensitivity of differential protection.A busbar protection is proposed based on time-domain full component model identification,utilizing the different equivalent fault models corresponding to internal and external busbar faults.This protection principle reflects the changes in the topology of the protected components themselves,and theoretically has the advantage of not being affected by power source characteristics.It is also applicable to other converter-type power grids.At the same time,the proposed protection is implemented in the time domain without the problem of phasor extraction,and the operation speed is fast.Finally,a simulation model is built in PSCAD/EMTDC to verify the reliability and speed of the proposed busbar protection.