What is generating the system frequency of your microgrid? Obviously important to maintain this to ensure stability of the network. Need to consider how you are going to match supply with demand from loads. Is it possible to add any battery backup / supercapacitors to assist with power balancing. Obviously the strategies to match the power sources with the frequency of the grid will vary depending on the type of source. For solar you will be generating DC and need an inverter to convert this to A.C. if you are using this as a frequency source for the network you will need an inverter that can operate in islanded mode. If you were including batteries in the system there are solar inverters that will also integrate with battery storage. For the generator there are different strategies for power matching including droop and isosynchronous. For the wind generator it will depend on the configuration of the generator. Quite likely you will have a permanent magnet generator in a smaller turbine producing AC that varies with the speed of the turbine this is rectified to DC with an inverter then providing synchronisation.

Of course you may also want to consider power factor correction depending on loads as well.

what about the gas engine(from biogas plant) case sir Gavin D. J. Harper ..how to synchronise with grid freq..here in this case system microgrid freq is 50hz..