A Control-Based Solution for Distance Protection of Lines Connected to Converter-Interfaced Sources During Asymmetrical Faults

Full-scale converter-interfaced renewable energy sources (CIRESs) can cause misoperation of distance relays installed in their vicinity. Such failure stems from the different fault behavior of CIRESs and synchronous generators (SGs), based on which available relays have been developed. Several measures have been devised to secure the performance of distance protection by modifying existing relays. This paper proposes a new approach to address misoperation of distance relays during asymmetrical faults by regulating the fault currents of CIRESs such that available distance relays function properly without requiring modification. The prime objective of this method is to mimic certain features of the symmetrical components of SGs' fault currents that affect distance relays. In the meantime, the proposed method satisfies the constraints of a converter, such as its limited phase current magnitude. As a result, correct operation of the distance relays close to CIRESs is ensured regardless of the fault conditions, including its type, resistance, and location. Some salient features of the proposed method are its simplicity, compatibility with off-the-shelf relays, and independence from the voltage and power rating of the CIRES. Moreover, the proposed method uses only local measurements, and so is cost-effective. PSCAD/EMTDC simulation studies verify the performance of this new method.