<p>With the continuous increase in penetration of inverter-interfaced renewable energy sources (IIRES), their impacts on traditional relay protection schemes are becoming increasingly prominent. This paper firstly illustrates the issues of percentage differential protection and alpha plane-based differential protection caused by IIRES’s integration. Enlightened by the concept of phasor-domain alpha plane, the concept of time-domain alpha plane is developed in this study. After analyzing the distribution patterns of trajectory points of current sampled value ratio under diverse conditions, a new differential protection based on point distribution coefficient is presented. To further improve the ability to recognize severe internal fault and be unaffected by external fault with current transformer (CT) saturation, a waveform variation coefficient is designed to adaptively alter the size of region X2. The operating performance of proposed method is meticulously examined in a digital-physical co-simulation platform. The results demonstrate that proposed method is well-behaved in the presence of IIRES and has good anti-interference performance in face of noise, outliers, CT error, and CT saturation.</p>