Microgrids are Low Voltage distribution networks comprising various distributed generators (DG), storage devices and controllable loads that can operate either interconnected or isolated from the main distribution grid as one controlled entity. The effect of the use of a Microgrid Central Controller (MGCC) to achieve this co-ordinate operation with regards to the potential economic benefits and the power losses avoided in both the local network and the upstream network are presented. Finally, a methodology based on the marginal emissions curve of the upstream network is presented, taking also into account the calculated losses is used for the environmental assessment of the co-ordinate operation of Microgrids. All the above studies have been applied to a typical LV Microgrid interconnected to an actual MV network using actual market prices and DG bids reflecting realistic operational costs.

Exploiting the benefit that one can get from large scale integration of microgeneration (G) requires the adoption of different control strategies at different distribution network levels. In that sense, MicroGrid (MG) and Multi MicroGrids (MMG) concepts may be seen as a way to facilitate integration of higher levels of G into the system. This paper describes new control and management functionalities used to take profit from the presence of microgeneration and active loads under MG and MMG concepts. MultiCriteria Decision Aid (MCDA) techniques are used to capture decision maker's preferences in evaluating the impact of MG and MMG concepts deployment and help selecting the best development strategy.

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SUMMARYThe effect of the use of a Microgrid Central Controller (MGCC) to achieve co-ordinated operation of various DG sources, storage devices and controllable loads with regards to the potential economic benefits and the power losses avoided in the local network is presented. Additionally, the effect of connecting numerous typical Microgrids in a typical medium voltage (MV) network regarding power losses and the emissions avoided is studied. The emissions avoidance calculation is based on the marginal emissions curve of the upstream network, quantifying also the calculated losses reduction impact on emissions avoidance. The presented results, based on a variety of realistic market prices time-series, various levels of renewable energy resource (RES) production and demand from different seasons, show clear benefits in terms of both losses and emissions avoidance. Finally, this paper performs a sensitivity analysis on the potential impact of the DG topology within a Microgrid on losses and emissions avoidance.