Fault Coordination Control for Converter-interfaced Sources Compatible with Distance Protection during Asymmetrical Faults

In this article, distinctive fault characteristics of converter-interfaced renewable energy sources (CIRESs) will result in the misoperation of traditional distance relays. To handle this issue, a new fault coordination control method is proposed to ensure the correct operation of distance relays. Combined with sequence boundary conditions, the relationship between the apparent reactance and the CIRES positive-sequence current angle is revealed. Based on this, a reasonable current angle is generated by adjusting current references of the controller to make the apparent reactance equal to the actual line replica reactance, so distance relays can detect the fault distance correctly. The proposed control method shows good performance for high resistance faults and operation in weak grids. Meanwhile, the proposed method is economical because it does not require revising the controller structure, and only local measured data are used. Furthermore, fault ride through requirements such as current limitation and reactive current injection are still being realized. Simulation analysis is performed in PSCAD and real-time digital simulator to validate the recommended scheme.