In order to solve the problem that the protection scheme based on the fault characteristics of traditional power supply is easy to malfunction and refuse to operate due to the change of network topology caused by the access of distributed generation to distribution network, a new longitudinal protection scheme based on the phase angle difference of current sequence is proposed. The scheme defines the phase difference of current negative sequence component and the positive sequence component as the phase angle difference of current sequence. By calculating the phase angle difference of current sequence components at the protection device, then comparing the phase angle difference value at both ends of the line, the fault inside and outside the circuit can be quickly identified. The scheme analyzes and simulates the influence of multi-point access and transition resistance of DG, and the existence of unmeasurable branches. Finally, MATLAB simulation software is used to simulate the protection scheme to verify the correctness of the protection scheme.
