Hitoshi Sugimoto’s scientific contributions

Electric power systems with increasing photovoltaic (PV) systems face concerns regarding degradation in frequency stability due to heightened output forecast errors. As a countermeasure, given the dynamic factors like demand, PV output, and meteorological elements, calculating the optimal reserve margin (ORM) becomes crucial for economic efficiency and resilience reinforcement. To ensure an efficient ORM, Artificial Intelligence (AI) is one of useful strategies used to analyze the combination of all the elements. However, AI is characterized by a black box problem, and to achieve transparency, AI needs to be transformed into explainable AI. To begin with, this paper analyzed all features importance using SHAP adopting a Gaussian process regression model. Then, relevant explanatory variables were selected to improve the prediction accuracy of the ORM. Finally, to verify the effectiveness, this paper planned day-ahead scheduling while securing the ORM determined by the proposed method. It executed detailed demand/supply and system frequency simulations as an operation. The proposed method decreased the risk posed by PV output forecast errors and shortage of reserve margin. Also, the maximum PV capacity increased from 96.2% to 166.2% while maintaining frequency stability.

Research on energy management systems for microgrids up to recent years has covered a wide range of time scales, equipment, and services. However, the roles and purposes of consumers and aggregators targeted in these studies are scattered, making it difficult to apply them to the actual construction of microgrids. This study comprehensively deals with these studies and proposes a scheme that can be applied to microgrid construction plans. The proposed scheme consists of a long-term planning stage that considers an outlook of up to renewable energy 100%, a stage that considers various roles and performs capacity design at the same time as annual planning, and a stage that emphasizes short-term operational planning that considers various equipment. This paper demonstrated the use of the proposed scheme and visualized various indicators such as capacities and schedules to facilitate discussion between each role in the microgrid construction plan.

This study focuses on the development of an energy management system (EMS) for a microgrid (MG) that prioritizes balanced demand-supply operation to accommodate the stakes of distribution system operator (DSO), consumers (CNSs), and aggregator (AGR). An innovative EMS model for MG is introduced, which integrates power interchange (PIC) through electric vehicle aggregation tracks (EVATs) within virtual distribution feeders (VFs). This model enables each PIC to determine its contribution to different areas and corresponding remuneration simultaneously. The research presents a problem formulation for leveling operations using mixed integer linear programming (MILP), explaining operation scheduling through case studies. The results demonstrate the economic disadvantages for CNSs and AGR of completely leveling of net load powers by DSO’s directives. Additionally, it is emphasized the significant role of PIC through EVATs, particularly in microgrids with surplus power of photovoltaic (PV) systems and less capacity of battery energy storage systems (BESSs).

Preliminary Study about Net Load Power Leveling by Energy Storage System and Power Interchange in Energy Supply and Demand Model in Regional System (Joint conference of Hokuriku chapters of Electrical and Information Societies 2022) 太陽光発電(PV)の余剰電力の発生および電気自動車(EV)の充放電の地理的・時間的な集中などによる地域系統の負荷の不均衡が問題視されている．本研究では，蓄電池(ES)の運用のみならずEVの充放電により地域系統間の電力融通(IC)を行い，地域系統の負荷の不均衡の解消を目指す．本論文では，その予備検討としてEVによるICを地域間の仮想配電線によるICと見立て，地域系統の正味負荷電力(NLP)の平準化に必要なICの量を求めることを目的とした．まず，地域系統の電力需給モデルにおいて定式化を行った．その後，シミュレーションを実施した．その結果，福井県のとある地域規模を想定した場合，2255 kWhのICによって負荷の不均衡が解消できることが示された．

The Virtual Synchronous Generator (VSG) can give virtual inertia and imitate primary control of the synchronous generator. This paper focuses on grid-following (GFL) type VSG for easy parallel operation compared to voltage source inverter. The grid frequency support of GFL-VSG can be achieved by controlling active power output using frequency deviation. However, this control causes the delay because of feedback for the virtual inertia. This paper proposes the GFL-VSG with the parallel installation of the governor and swing equation to reduce the delay. The numerical simulation was carried out to verify its effect and grid frequency support of the proposed GFL-VSG. The result shows that grid frequency support by GFL-VSG is faster compared with the conventional method, and the gate frequency is more stable with multiple several VSGs.