This paper designs a control and protection system of 12-pulse DC ice-melting device based on DSP. The system adopts constant current control strategy to ensure stable ice-melting current output, and in the event of failure to ensure the safety of equipment and substation equipment. Three-phase transmission line defrosting switch and ground line defrosting simulation models are established. No-load booster test is needed before the ground line melts ice. To prevent the ground wire insulation strength is insufficient, so that the ground wire of the access device and the adjacent ground wire gap may be broken, resulting in ground fault damage converter station equipment. The simulation model is established by using the ground wire ice melting parameters of Niuzhai converter station, and the simulation analysis is carried out on the no-load booster test of the ground wire. The results show that the ground fault is caused when the ground wire is broken, the voltage deviation protection can act quickly, ensuring the safety of the ice melting device and the substation equipment. The voltage deviation protection proposed in this paper has been verified in the DC ice-melting equipment of Niuzhai converter station. This work is supported by Science and Technology Project of China Southern Power Grid (No. RXSVC14090201) “Guizhou-Tongren-Bijiang (Daxing) 500 kV Power Transmission and Transformation Melting Ice and SVC Device”.