A Single-Ended Whole-Line Protection for Active Distribution Networks Using Constructed Resonant Boundary Element

Active distribution networks (ADNs) exhibit characteristics such as topological flexibility and bidirectional power flow, which distinguish them from traditional distribution networks (DNs). These intrinsic characteristics present significant challenges to traditional single-ended protection schemes deployed in conventional DNs. Boundary protection, which is based on the coordination between the relay on one side of the line and the boundary element at the opposite terminal, can achieve rapid fault detection across the entire line utilizing exclusively local information, thereby offering a promising solution for addressing the protection challenges in ADNs. In this paper, a method for constructing a resonant-type boundary element (RBE) is proposed, based on the analysis of the performance of various boundary element types. Furthermore, the fault characteristics for internal and external faults are analyzed. Within the specified blocking frequency band (BFB) of the RBE, the voltage during an internal fault exhibits significantly higher magnitudes compared to those during external faults. Based on this distinction, a voltage energy criterion incorporating fault phase angle correction is subsequently proposed. Simulation and experimental results demonstrate that the proposed protection method, in conjunction with the designed RBE, can accurately and rapidly distinguish internal and external faults.