Voltage-Sag Origin Detection in Smart Grids for Enhanced Resiliency

The prompt and precise identification of voltage-sags in smart grids is crucial to manage voltage-sag mitigation, system restoration, and recovery effectively while ensuring the security and resiliency of the grid. Given that faults are a primary cause of voltage-sag events, accurately detecting these faults can significantly speed up the mitigation and recovery process. However, as the adoption of Inverter-based Resources (IBRs) increases, traditional fault-detection schemes have become inadequate because they overly depend on evaluating fault currents, which are limited by these IBRs. This paper introduces a methodology for detecting and identifying the origin of voltage sags, enabling the determination of whether a fault is located upstream or downstream from the system's PCC. The simulation results show that the technique is faster and more efficient compared to existing methods in the literature. The proposed fault detection algorithm utilizes a voltage/current estimation technique in combination with Tellegen's theorem to pinpoint the accurate geographical location of the voltage-sag origin in Active Distribution Systems (ADSs). A case study is conducted on a modified IEEE 33-bus distribution network with a three-phase balanced 12.66 kV system, incorporating IBRs throughout the network, to evaluate the algorithm's effectiveness.