The micro-grid (MG) is connected with the home wireless network called (HAN) as well as with the electric utility grid via the LAN. The smart meter (SM) also is connected wirelessly with both and controls the supply and demand side of power. The micro-grid also receives (via the Ethernet) the status of power generation from the off-grid power sources (wind turbine farms, solar PV farms, fuel cell stacks). 

If sufficient power is generated from the off-grid sources, then the power supply from the utility grid is stopped and visa versa.

To help you how it all works, there is a nice software called Homer for Micro-grid simulation and you can download a free copy of this software from Carnegie Mellon University.

Hope this helps answer your question.

Professor Yehia Khalil

Yale University

USA

Hi Tinnes,

I have simulated standalone PV/battery based microgrids in PSCAD. As Dr. Yehia emphasized, that communication basis are usually used to relay references to DG units for frequency and voltage stability. Just to add more, there are three main layers in microgrids; primary, secondary and tertiary. The primary layer consist of all the basic control for individual DG units e.g in case of PV we will look into MPPT control or even a boost converter control at the primary layer. The secondary layer is all related to communications and references relaying to the units. These references could be from the droop controller or other voltage and frequency references. For microgrids as previously mentioned we look into LAN and wireless as the main communication methods. Hope this answers your query. 

http://cordis.europa.eu/result/rcn/52934_en.html

OPEN-GAIN (Optimal engineering design for dependable water and power generation in remote areas using renewable energies and intelligent automation)

The OPEN-GAIN project (Optimal Engineering Design for Dependable Water and Power Generation in Remote Areas Using Renewable Energies and Intelligent Automation) submitted by the Automation Laboratory (Coordinator) to the sixth European framework program for research and technological development has been ranked very positively by the technical committee.

In this project a mobile plant for water and energy co-generation is developed now with partners from Spain, Greece, Algeria, Jordan, Tunisia and Lebanon under the coordination of the Automation Lab. In addition to conventional diesel generators, renewable energy sources wind and sun shall intensively be used. A high-level of automation is employed for adapting the operating conditions to the strongly varying renewable energy supply and to enhance the plant's dependability. [more ...]

Thank you everybody for your input. You answered my question in one way or the other.