Abstract: A HVDC system has some characteristics which should be considered in AC filter connection protection, such as harmonic, island operation, breaking capability of circuit breaker and TA saturation. An AC filter connection protection scheme was proposed with the consideration of these characteristics. The scheme includes differential protections taking accounts of TA saturation and over voltage protections involving the factors of harmonic, AC over voltage, circuit breaker capacity and island operation. The proposed scheme has been successfully applied to a number of domestic projects of HV and EHV DC. Operation performences show that the proposed protection scheme can provide a good protection for AC filter connection.

Key words: HVDC transmission, harmonics, island operation, over voltage, protection of AC filter connection