How grid connected solar microinverter can know that grid power has failed?

I need to design grid connected solar micro inverter. I have studied that micro-inverters (solar) can be connected with each other to provide power needed by the grid. Generally one micro-inverter provide 230W power and they can be connected to each other to provide more power. Grid connected solar inverter sence the grid volatge and frequency to provide exact voltage level and frequency voltage to the grid. If the grid power fails then grid tied micro inverter need to shutdown its power to the grid. Now suppose there are multiple microinverter at different locations supplying power to same grid. Now in case of grid power failure how microinverter can know that grid power has failed, because all invertfrom are supplying power to same grid (with same amplitude and frequency)so if power from one source fails (from main electricity generation company), power should be available from other source (micro-inverter) on the grid. or I would say that how micro-inverter can know that the grid voltage they are monitoring is actually from main grid (from main electricity generation company), not from other microinverter.

Re: Solar Micro inverter

Yes this can be an issue when you have many inverters. Typically the power supplied by inverters is <2-3% of total grid power.

So, make a circuit in which you have an infinite power source (say grid) connected to 100 inverters in parallel. This is similar to a voltage source with zero impedence connected to multiple voltage sources with a highZ. Where do you think the currents flow?

Re: Solar Micro inverter

Thanks for reply.
There is one term in solar inverter called anti islanding. Which is used to remove power from Grid connected solar inverter even if grid power fails.
there are load circuits in the electrical system that happen to resonate at the frequency of the utility grid, the inverter may be fooled into thinking that the grid is still active even after it had been shut down. Can you give nay idea how grid connected solar inverter get disconnected in these cases from the grid in case of grid power fqilure.

due to frequency mismatch