Mutual inductance between adjacent lines is the root cause of mal-operation of the zero-sequence direction component under weak current and strong magnetic situations. The correct working condition of the zero-sequence direction component is analyzed and the difference in fault characteristics is obtained by comparing the electric quantity of the lines when the zero-sequence direction components are in correct operation and mal-operation. Consequently

the fault characteristic of the line in mal-operation is found that the fault components of the three-phase currents are the same. By identifying this characteristic with the model error algorithm

a method is proposed to prevent the mal-operation of the zero-sequence direction component. To test the effectiveness of the proposed method

a double-circuit transmission system on the same tower is built based on the PSCAD software. Simulation results show that the method is reliable in identifying the healthy line. When a line is under fault

the zero-sequence direction component of adjacent healthy lines can be correctly blocked to avoid mal-operation. In contrast

the zero-sequence direction component of the fault line will be working properly instead of being blocked. The proposed method is capable of identifying mutual inductance between lines under weak current and strong magnetic conditions while improving the applicability of the zero-sequence direction component. This work is supported by Sate Grid Corporation of China.