Treffer: Integrating distributed energy resources in power distribution systems: A comprehensive review of impacts, challenges, and opportunities from a distribution system operator's perspective.

Distributed energy resources (DERs)—including solar photovoltaics (PVs), electric vehicles (EVs), and energy storage resources (ESRs)—are reshaping power distribution systems (PDSs) through decentralized generation, bidirectional energy flows, and enhanced demand-side flexibility. While DERs can improve power quality and support grid stability, their rapid growth presents significant challenges for distribution system operators (DSOs), who must transition from managing passive, radial networks to coordinating active, multidirectional systems. This paper provides a comprehensive review of DER integration in PDSs from a DSO operational perspective. In contrast to broader reviews centered on macro-policy or transmission-level issues, we emphasize DSO-specific challenges and opportunities at the distribution level. We present an analytical framework for DSO-centric DER integration, assess the limitations of widely used test models—particularly their ability to represent low-voltage (LV) secondary circuits—and examine both the individual and coordinated operation of PVs, EVs, and ESRs. The review synthesizes practical methodologies for optimizing DER performance, examines emerging solutions to future challenges—including voltage management, advanced technology integration, congestion mitigation, protection adaptation, and cybersecurity—and identifies critical gaps in LV observability and data accessibility. By integrating these insights, the paper aims to guide effective, DSO-led strategies for reliable, efficient, and equitable DER integration in modern power grids. • DSO-Centered Review of DER Integration: This paper provides a comprehensive review of DER integration at the distribution level, focusing on the unique operational, economic, and technical challenges faced by distribution system operators (DSOs) under high DER penetration. • Limitations of Existing Test Feeders: It critically examines IEEE and European test feeders, identifying their shortcomings in representing low-voltage (LV) dynamics, secondary-circuit behavior, and DER aggregation, and underscores the need for detailed LV-level datasets and time-series modeling. • Coordinated DER Operation Framework: The study emphasizes the importance of coordinated operation among PVs, EVs, and ESRs, demonstrating how their complementary interactions enhance grid stability, power quality, and flexibility, providing a practical foundation for DSO-centered management and future grid optimization. [ABSTRACT FROM AUTHOR]