When we develop a distributed grid using renewable energies, what are factors to be considered when they are coupled together, and what kind of controls can be used to integrate the sources such as wind, solar, biogas, battery and vehicle to grid?
Renewable energy is mainly intermittent. In order to overcome this intermittency in a distributed generation application, you need to consider the available resources at your location and use energy storage to minimize the effect of intermittency. Energy could be stored thermally in storage tanks, electrically in battery banks, or carried by hydrogen and then stored. When you are integrating different renewable energy sources together (whether in a gird-parallel or grid-independent fashion), you need to develop an energy management strategy to efficiently meet as much of the demand using your system (a wise decision would be to let the grid meet sharp demand surges instead of oversizing your system) while minimizing your investment cost. The following papers could be very helpful for your case:
1) Sizing and Energy Management of a Stand-Alone PV-Hydrogen-Battery-Based Hybrid System.
2) Power Management of a Stand-Alone Wind-Photovoltaic-Fuel Cell Energy System.
3) A fuzzy logic energy management system for polygeneration microgrids.
4) Sizing methodology for hybrid systems based on multiple renewable power sources integrated to the energy management strategy.
Though the concept presented by Omar Sharaf would not need any proof for it's theoretical validity, I would like to present an alternative cost effective concept that you might find interesting.
Today One of the primary factors hindering large penetration of renewable sources in domestic level is the prohibitively high cost associated with the storage systems. Therefore alternative means should be found to overcome the problems introduced by the randomly fluctuating renewable energy production. A study carried out in Germany showed that aggregation of large number of wind energy sources would cancel the fluctuations caused by each other and hence the total capacity of the energy storage required to balance the overall fluctuation would reduce.
On the other hand the prospective Plug-in Electric Vehicles would also be controlled to absorb the fluctuations resulting from renewable energy sources. Similarly many other devices within a microgrid could be collectively controlled to achieve better optimization with regard to cost and carbon foot print of the energy.
My paper on the title "Active And Reactive Power Balancing Of Ubiquitous Power Network Considering Voltage Constraints" presents the subject in more detail. If interested find it in the following link