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In this paper the design and manufacturing processes for coreless axial flux permanent magnet generators are described for low cost rural electrification applications, where local production of small wind turbines is considered. The process is based on already existing open source design and construction manuals, while a systematic approach to designing generators of varying nominal power and for grid connection or direct battery charging schemes is described. The manufacturing process of a 3 kW small wind turbine generator for grid connection is used as a case study. Emphasis is given to the use of simple tools and techniques to achieve a lower cost, while intricate steps in the manufacturing process are described in more detail. The generator design is simulated and the constructed machine is tested in the laboratory.

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According to CIGRE WG C6.21Microgrids are electricity distribution systems containing loads and distributed energy resources (DERs) (such as distributed generators, storage devices, or controllable loads) that can be operated in a controlled, coordinated way either while connected to the main power network or while islanded. The different parts of the microgrid can be interconnected via an AC link forming AC microgrids or via a DC link forming DC microgrids. The notion of control is critical in the definition of microgrids. In fact, what differentiates microgrids from Distribution Grids with distributed energy sources and loads lies in the capabilities to manage and coordinate the available resources, so that they appear to the upstream network as a single coordinated unit. The developments in power electronics that are used for the interconnection of inverter‐based generation and storage units, such as photovoltaics and batteries, within microgrids have provided the possibility of incorporating advanced functionalities in the control of the distributed resources. Droop curves such as active power – frequency (P–f) and reactive power – voltage (Q–V), similar to the ones of traditional rotating machines and together with the capability of remotely controlling them, allow the application of advanced control strategies for microgrid operation. Advanced Information and Communications Technology (ICT) provides further opportunities for the application of intelligent techniques in microgrids decentralized control.This chapter deals with microgrid control and operation, including both primary and secondary voltage and frequency control and optimal dispatch among the DERs. Centralized and decentralized approaches are discussed, and typical results are displayed, obtained from laboratory setups at the Electric Energy Systems Laboratory of the National Technical University of Athens.