Active Phase Control to Enhance Distance Relay in Converter-Interfaced Renewable Energy Systems

For the converter-interfaced renewable energy systems, due to the inherent intermittent characteristic of renewable energy and the AC fault current limiting of interfaced converters, the conventional overcurrent protection suffers from low reliability. Distance protection can be adopted in light of its robust performance. However, various AC fault ride-through strategies of converter-interfaced sources will cause the large phase difference between the operating current of the distance relay and the fault current, which leads to the mal-operation of the distance relay. In this paper, an active phase adjustment control is proposed for the converter-interfaced renewable energy systems to enhance the reliability of the distance relay. This control scheme firstly calculates the phase difference between operating current and fault current by only using local measurements. Then, the phase difference is eliminated via phase angle adjustment. As a result, the correct operation of the distance relay can be ensured. The performance of the proposed method is tested in a radial threeterminal system in PSCAD/EMTDC