This paper focuses on the energy storage system and the power electronic interface included in microsources of the CERTS microgrid. CERTS stands for the Consortium for Electric Reliability Technology Solutions. The consortium was formed in 1999 to research, develop, and disseminate new methods, tools, and technologies to protect and enhance the reliability of the U.S. electric power system and efficiency of competitive electricity markets. To provide the plug-and-play feature and the power quality requirements of the CERTS microgrid, all microsources regardless of their prime mover type must have a unified dynamic performance. This necessitates attaching an energy storage module to some or all of the microsources. The storage module is attached to the prime mover through a power electronic interface that couples the microsource to the microgrid. Details of the energy storage module, the power electronic interface and the corresponding controls are described. Performance of an example microsource, which includes a synchronous generator, a storage module and an electronic interface, is studied. Dynamic performance of the example microsource when operating in the CERTS microgrid is evaluated based on digital time-domain simulations in the EMTP-RV software environment. Effectiveness of the storage module, the electronic interface and the corresponding controls in enhancing the microsource performance is verified.

This paper presents a new control strategy for islanded (autonomous) operation of an electronically-coupled Distributed Generation (DG) unit and its local load. The DG unit utilizes a Voltage-Sourced Converter (VSC) as the coupling medium. In a grid-connected mode, based on the conventional dq-current control strategy, the VSC controls real-and reactive-power components of the DG unit. Subsequent to an islanding detection and confirmation, the dq-current controller is disabled and the proposed controller activated. The proposed controller utilizes (i) an internal oscillator for frequency control and (ii) a voltage feedback signal to regulate the island voltage. Despite uncertainty of load parameters, the proposed controller guarantees robust stability and prespecified performance criteria, e.g. fast transient response and zero steady-state error. Performance of the proposed controller, based on time-domain simulation studies in the PSCAD/EMTDC software environment, is also presented.©2008 IEEE.

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This paper investigates the use of an AC-AC matrix converter, as an alternative to AC-DC-AC converter system, to interface a high-speed micro-turbine generator (MTG) to a utility grid as a distributed generation unit. A new switching strategy and a control mechanism for the converter are presented. Based on time-domain simulations in the PSCAD/EMTDC environment, the dynamic behavior of a micro-turbine generation system, including the dynamic models of the micro-turbine (thermodynamics), generator, matrix converter, converter control and micro-turbine control, is studied. The studies conclude that a matrix converter is technically a viable option to interface a MTG to a utility grid.

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