Hierarchical-power-flow-based energy management for alternative/direct current hybrid microgrids

Modern microgrids are systems comprising both Alternative Current (AC) and Direct Current (DC) subgrids, integrated with Distributed Generations (DGs), storage systems, and Electric Vehicles (EVs) parking facilities. Achieving stable and reliable load flow control amidst varying load, generation, and charging/discharging strategies requires a hierarchical control scheme. This paper proposes an hourly power flow (PF) analysis within an Energy Management System (EMS) for AC/DC Hybrid Microgrids interconnected via an Interlinking Converter (IC) in both grid-connected and islanded modes. The framework operates within a two-level hierarchically controlled platform. Tertiary control at the top level optimizes DGs' reference power for generation and consumption, minimizing power purchase costs and load shedding in grid-connected and islanded modes, respectively. DG converters employ current control mode to share their power references as the primary controller. While no secondary controller is adopted in this scheme, the Battery Energy Storage System (BESS) in islanded mode utilizes P/Q droop control to maintain voltage and frequency in the AC subsystem. Power sharing between AC and DC subgrids through IC is determined by the difference between AC grid frequency and DC link voltage. Integration of controlled converters’ buses into PF equations enables solving the unified system using the traditional Newton-Raphson (NR) method. A segment of a real distribution grid planned for installation in Italy under the HYPERRIDE project serves as a case study. Comparison with MATLAB/Simulink results confirms the effectiveness, precision, and convergence speed of the proposed model and control schemes, demonstrating efficient load distribution and voltage/frequency restoration in islanded mode

Interview no. 296

Raza Unida Party nationally, statewide, and locally

Migration and Development: a Bottom-Up Approach. A Handbook for Practitioners and Policymakers

This handbook is produced in the framework of the European Commission- United Nations Joint Migration and Development Initiative (JMDI). It is a four-year, 15 million euro programme supporting small-scale organizations in their concrete efforts towards linking migration and development. The JMDI reflects the acceptance of and growing interest in the strong links between migration and development. The UN High Level Dialogue on Migration and Development in 2006 and the subsequent Global Fora on Migration and Development underscored international migrants’ contribution to origin and destination countries

Migration et Développement: une Approche Issue par la Base. Un Manuel pour les Practiciens et les Decideurs Politiques

Introduction: Ce manuel est produit dans le cadre de l’Initiative conjointe pour la Migration et le Développement (ICMD) de la Commission européenne et des Nations unies. Il s’agit d’un programme sur 4 ans d’un montant de 15 millions d’euros qui soutient les organisations à petite échelle dans leurs efforts concrets visant à établir un lien entre la migration et le développement. L’ICMD reflète la reconnaissance des liens étroits entre migration et développement et l’intérêt croissant qu’ils suscitent. Le Dialogue à Haut Niveau des Nations unies sur la Migration et le Développement en 2006 et les Forums mondiaux ultérieurs sur la Migration et le Développement ont souligné la contribution des migrants internationaux dans les pays d’origine et de destination

Block and graft copolymers made of 16-membered macrolactones and l-Alanine: a comparative study

Block and graft poly(macrolactone)-poly(a-amino acid) copolymers made of l-alanine and pentadecalactone or globalide respectively, are prepared. A sequential ring-opening polymerization (ROP) copolymerization route consisting of two stages, the first devoted to the preparation of the amino-functionalized poly(macrolactone) and the second to the amino-initiated polymerization of l-alanine N-carboxyanhydride (Ala-NCA), is followed for the synthesis of both types of copolymers. Poly(l-alanine) segment lengths are accurately controlled by adjusting the macroitiator/Ala-NCA ratio used for reaction in the second stage. Block copolymers are semicrystalline with the poly(pentadecalactone) block crystallizes well in a separate phase and the poly(a-amino acid) block arranged in either the a-helical or ß-sheet structure in a ratio that is depending on composition and temperature. Graft copolymers are amorphous but with the poly(a-amino acid) side chains arranged in a more or less regular conformation. Nanoparticles with a diameter of around 300 nm and moderate positive Z-potential can be obtained from the block copolymers by self-assembling in water whereas graft copolymers are unable to render recognizable objects of nanometer-dimension under similar conditions.Peer Reviewe