A Novel Superimposed Positive Sequence Impedance-Based Fault Detection Technique in Microgrid

Microgrids are essential to advancing smart grids, improving cost reduction, reliability, and increased penetration of distributed generation (DGs) systems. However, integrating the bi-directional converter and distributed energy resources (DERs) poses challenges to protection coordination. Thus, a robust protection approach is essential to address the complexities associated with microgrid systems. This article proposed a novel fault detection method, incorporating superimposed positive sequence impedance to detect faults within a microgrid system. The <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Delta \mathrm{Z}$</tex> method is numerically defined as the ratio of the sum of superimposed positive sequence impedance at the sending and receiving end of the feeder to the larger one amongst both of them. The internal and external faults are identified using the threshold value. A <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Delta \mathrm{Z}$</tex> parameter-based method is verified across various scenarios, including numerous fault types, locations, fault resistances, and operating conditions such as capacitor switching and load changes. Furthermore, the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Delta \mathrm{Z}$</tex> approach displays robust performance under adverse conditions, including noise, sampling frequency variations, and simultaneous and evolving faults. The proposed scheme's effectiveness has been validated using MATLAB/SIMULINK software. This research highlights the perspective of the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$\Delta \mathrm{Z}$</tex> technique as a reliable tool for enhancing fault detection in microgrid systems.