## 2 Methodology for Selection of Studies
### Synthesis of the Selected Studies  
The 94 studies selected for synthesis form a robust foundation for addressing the research objectives. Figure 4 provides a detailed visual representation of the bibliometric analysis, including trends in the publication volume, journal/conference distributions, and other relevant metrics. The cumulative H-index of 30 for the selected studies reflects their significant influence in advancing the understanding of energy management systems within P2P frameworks. The high citation rates observed for many works within this dataset suggest that these studies are widely recognized and can serve as foundational references for subsequent research in this area. The temporal distribution of the selected studies (see Figure 4) reveals clear trends in the research activity over the past decade. This analysis highlights a steady increase in academic interest, particularly from 2021 onwards, coinciding with the growing emphasis on renewable energy integration, DES, and P2P energy trading. The peak in 2022, with 26 studies, means a heightened focus on these topics, potentially driven by advancements in multi-agent optimization and robust control techniques. Figure 3: Verification matrix for evaluating the selected studies. The selected studies were published in a diverse range of reputable journals and conferences, showing the multidisciplinary nature of the research domain. Figure 4 also summarizes the distribution of studies by publication venue. This distribution indicates that the field is well-represented in high-impact journals and conferences, showcasing its multidisciplinary nature and broad applicability. Key contributions come from venues such as IEEE Transactions on Smart Grid, which has led 11 studies and emphasizes its role as a premier platform for cutting-edge research in smart grid technologies, hierarchical optimization, and distributed energy management. Applied Energy follows with 10 contributions, reflecting its strong focus on sustainability and energy efficiency, particularly through practical and innovative approaches to energy system optimization. IEEE Access, with nine studies, highlights emerging technologies such as blockchain, smart contracts, and MAS, benefiting from its open-access model to enhance visibility and interdisciplinary collaboration. The International Journal of Electrical Power and Energy Systems, featuring five studies, emphasizes advanced optimization models and technical-economic perspectives on power systems, particularly in decentralized contexts. IEEE Transactions on Power Systems, contributing four studies, reveals its focus on power system operations and planning, addressing challenges in distributed generation, energy storage, and robust control frameworks. Energies and IEEE Transactions on Industrial Informatics, each contributing three studies, demonstrate complementary focuses, with Energies bridging theoretical advancements and practical implementations in renewable energy systems. At the same time, IEEE Transactions on Industrial Informatics delve into the intersection of industrial applications and informatics, particularly in smart grid technologies and distributed control. Collectively, these seven journals account for a substantial portion of the selected studies, reflecting the prominence and diversity of hierarchical, multi-agent, and robust optimization systems in modern energy research. The presence of a significant number of studies in diverse venues highlights the multidisciplinary scope and broad applicability of research in hierarchical, multi-agent, and robust optimization systems for P2P energy management. Figure 4: Distribution of the selected studies by journal/conference and year, and H-index calculation. Figure 5 provides a word cloud map constructed from the authors' keywords across the 94 selected studies by using an online free tool: www.freewordcloudgenerator.com (accessed on 25 January 2025).