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The control algorithms proposed to improve load sharing, stability, and power quality in microgrids need rigorous testing. Real-time emulation is one of the proven approaches to provide realistic testing environments for the development of products and control algorithms. Typically, for microgrid system-level testing, individual component-level (source or load) emulators are employed: hardware test bed clusters. These use multiple converters, increasing control complexity and consuming space. In this article, we propose a flexible microgrid system emulator, based on a single converter for the testing of a complete microgrid, at any node selected by the user. This is unlike the case of emulators proposed in the literature till date, which use a large number of converters to emulate the system dynamics, wherein each converter is used to mimic the behavior of one particular component, such as a single source or a single load. The modeling and control aspects are discussed, and the accuracy of the model developed and the working of the emulator are established through simulations and experiments on a laboratory prototype, respectively, considering the case of a simple two-distributed-generator-based microgrid for various scenarios. [ABSTRACT FROM AUTHOR]

Microgrids are subjected to limits on system voltage and frequency deviations for transient and steady state operation. Similar to a conventional power system with rotating generators, inertia and damping of frequency are necessary for frequency profile and stability of an isolated microgrid. This work proposes an approach to analyze inertia and frequency damping coefficient for a system based on the fact that sources relatively close to each other observe similar transients in frequency within an isolated microgrid. This is validated through bode plots and simulation. The approach allows defining the system response to transients in frequency in terms of individual source response using standard frequency mode parameters such as damping and inertia. Further, to optimize the overall system response so that sources share the frequency regulation requirement, a novel strategy is proposed to design individual source inertia and damping coefficient based on the source capacity. An experimental setup consisting of a microgrid system having three inverter-based sources working as virtual synchronous generators operating in parallel has been set up to verify the analysis. [ABSTRACT FROM PUBLISHER]

Generation is shifting from a centralized power generating facility having large synchronous generators to distributed generation involving sources of smaller capacity. Most of these sources require inverters on the front end while being connected to the grid. Lower available kinetic energy, coupled with less short-circuit current ratio compared to large synchronous generators, compromises the transient stability of the microgrid when isolated from the main grid. Sources in the microgrid use droop control to share power according to their capacity without any form of communication. This paper proposes a novel controller for inverters to improve the frequency response of microgrid under disturbances involving large frequency deviations. It also discusses design of various parameters defined for the proposed control. The microgrid, which has two inverters and two synchronous generators, is simulated using Simulink/MATLAB software to test the proposed control strategy. [ABSTRACT FROM PUBLISHER]