How to measure impedance of the grid.

[Cees Keyer]

Dear All,

I am looking for a way to measure the impedance of the power grid.
The problem is:
I have photovoltaic cells which are pumping power into the grid when i do
not use that much power myself.

But i would like to prohibit so called Isle powering (I don't know the
correct term for it in English).

That is: If i switch of the grid in my switch box the sun power should be
switched off by it self.
This can be done by continuous measuring the grid impedance.

But how do i do that? Any suggestions would be welcome

tnx in advance for any suggestions.

PS I am not native speaking English so excuses for awkward terms etc.

 

[neon]

Why you need the inpedance from the GRID. that is lame my friend you will never be able to do that . instead put a very low value hi power resistor and monitor voltage across it if positive lets say it suck power if negative it source power that is it. the power co. do that with no problems.The usa is one big grid with thousends of co. and guess what they continously buy and sell power every day from each other this way.