Protection method for identifying fault braches based on zero-sequence active ratio

The invention relates to a protection method for identifying fault braches based on the zero-sequence active ratio. The method includes: collecting bus voltage U1 and branch current I1 of a branch 1, collecting bus voltage U2 and branch current I2 of a branch 2, and collecting neutral point current I0 of a low-voltage side; calculating zero-sequence voltage U10 and zero-sequence current I10 of the branch 1; calculating zero-sequence voltage U20 and zero-sequence current I20 of the branch 2; calculating zero-sequence active power P1 of the branch 1, and calculating zero-sequence active power P2 of the branch 2; if P1>3P2, determining that earth fault happens to the branch 1, sending a tripping command to a circuit breaker QF1, if P2>3P1, considering that earth fault happens to the branch 2, and sending a tripping command to a circuit breaker QF2; otherwise, considering that fault happens to both the branch 1 and the branch 2, and simultaneously sending tripping commands to the circuit breakers QF1 and QF2. By