Fault coordination control for converter-interfaced sources compatible with differential protection during asymmetrical faults

Abstract

Converter-interfaced renewable energy sources (CIRESs) may have a different fault current angle with synchronous generators (SGs), so the large angle difference on both sides will cause low sensitivity or failure for traditional proportional braking differential protection. So as to cope with this issue, a new fault control strategy is put forward. By analyzing the phasor diagram during asymmetric faults, a reasonable phase angle of the CIRES fault current is determined to reduce the angle difference below 60°, and corresponding current references of the controller are calculated. In this way, the proposed method can make CIRESs compatible with differential protection, so it is economical since the protection device is not necessary to be updated. In addition, it also shows good performance for different fault points, high-resistance faults and different power factors before the fault. Moreover, typical fault ride through (FRT) conditions including fault current restriction and reactive power support are still being satisfied while the controller structure does not require to be altered. Simulation results in PSCAD validate the proposed approach can be used for different fault scenarios.