A time-domain distance protection method applicable to inverter-interfaced systems

Traditional distance protection method exists serious adaptability problem in the inverter-interfaced systems. To improve its performance, the authors propose a time-domain distance protection method applicable to inverterinterfaced systems in this article. First, the authors analysis the reason for the degradation of distance protection performance in the studied systems, and then propose a strategy for inverter that can create two irrelevant fault states to solve it. Subsequently, based on the electric quantities under the two fault states, two sets of fault loop equations can be established. And by combining the irrelevant fault loop equations, the time-domain fault distance algorithm suitable for inverter-interfaced systems is derived, which can calculate fault distance directly. Finally, the PSCAD/EMTDC results demonstrate that the method has good accuracy and stability. It is immune to fault resistance and system parameters, and can be utilized for both single circuit systems and double circuit systems.