Novel method for adaptive relay protection in distribution systems with electronically-coupled DERs

Abstract

In this paper, a novel adaptive relay protection coordination method for large-scale distribution systems with electronically-coupled distributed energy resources (DERs) is proposed. Electronically-coupled DERs cannot be represented with the traditional fault models, nor the traditional relay protection coordination methods can be used for systems with these DERs. Therefore, highly precise models of electronically-coupled DERs for relay protection purposes are developed. Afterwards, a novel method for adaptive relay protection coordination in systems with high penetration of these DERs is proposed. The proposed method considers DER disconnection times, as defined in Fault Ride Through requirements, as well as accurate models for electronically-coupled DERs, dependable on fault severity. The accuracy of the method is verified on the IEEE 37 distribution system test example, as well as on one real-life 186-bus feeder. Afterwards, the computation time required for complete calculation is measured for several large-scale systems, with up to 5320 three-phase busses. Advantages of the proposed method relative to existing ones are clearly illustrated.