The earth fault in the high-voltage capacitor of direct current(DC)filter will greatly affect the security and stable operation of DC transmission system. The existing high-voltage capacitor earth fault protection of DC filter has the problems of poor selectivity

low sensitivity

difficult setting of definite value and so on. A new type of high-voltage capacitor earth fault protection criterion and protection scheme

which is independent of the system operating conditions

is proposed based on the requirements of DC transmission system and DC filter high-voltage capacitor protection. The proposed fault protection criterion and scheme is acquired by combining with the structural characteristics of H-type high-voltage capacitor and simplifying the earth fault model. The problems in the existing protection are solved by the proposed scheme. The actual ultra-high-voltage direct current(UHVDC)engineering simulation model is used to simulate the high-voltage capacitor earth fault. The validity and correctness of the proposed protection criterion and scheme are verified.