Comprehensive framework for evaluating protection schemes in active distribution networks

Active distribution networks (ADNs) are evolving into highly complex systems due to the growing penetration of distributed energy resources (DERs), as well as advanced operation, control, and protection schemes. This increasing complexity poses significant challenges for reliable functioning, where conventional schemes often fail to provide adequate performance under realistic operating conditions. Motivated by these challenges, this paper proposes a comprehensive framework for the evaluation of ADNs, with a specific focus on fault analysis and protection strategies. The framework is built upon a detailed network modelling approach that explicitly represents lines, loads, conventional generation, and inverter-integrated DERs, each tailored to capture realistic fault behaviour. This modelling foundation enables a rigorous assessment of protection schemes under practical conditions such as line capacitance and asymmetry, infeed and outfeed currents, and variable fault resistances. A key novelty of this work lies in demonstrating how the framework enables the design and evaluation of advanced protection strategies, bridging the gap between idealised studies and realistic system behaviour. As an application, the paper evaluates the performance of an impedance-based distance relay, where results show that, for fault resistances below 60 [Ω], the conventional approach exhibits errors as high as 311.029%. In contrast, an improved impedance-based relay limits the error to 6.021% or lower, even under challenging network conditions. These findings confirm that the proposed methodology not only enhances protection analysis but also serves as a versatile and adaptable blueprint for broader ADN studies, offering valuable insights into operation, control, and future research directions.