Measuring 0.1Hz–2Hz AC Current (10uA–2A) at 800Vpp Square Wave Source

I want to measure very low frequecy (0.1Hz to 2Hz) AC current(10uA to 2A).
I have attached image of equivalent circuit diagram.
Power is coming from a source with 1Hz freq. and 800V peak-to-peak voltage. shape of wave is square.
I want to design a current measurement device which can measure current flowing through R_LOAD. 
Please help me with this project.
 

What is it for?  In either event add in a low value resistor,  ~0.05 ohms and throw a op amp across it and than scale the gain to be in accordance with the amperage you want to see.  The question is do you want to do it low or high side of the load.  Since your going to be taking the voltage drop across the shunt resistor you dont have to worry about the 800Vp-p input into the opamp, but I'd take some time to think about how to isolate it still from the circuit.  Especially since anything that you are going to use to display the amperage is going to be a much lower voltage tolerant device.

MOST  IMPORTANT!!! 600V CAN KILL. Do you know enough to protect yourself. Your question suggests not. Get advice from someone who knows.At 1 Hz the frequency is too low to use a transformer for isolation and your dynamic range is probably too high to use a single approach. For currents from about 100mA, maybe  (you will need to check closer) I would suggest one of several products from Allegro. They are Hall effect and  provide isolation and no need for DC supply voltage at the input.  I have used the higher current  ACS730 and they aren't very sensitive below about +/-0.5A.if I remember correctly. Beware the ACS70331 since it won't be able to withstand the 600V.
Using this device is simplicity itself. BUT AGAIN, BEWARE 600V

Yes,at 1 Hz frequency is too low to use a transformer for isolation.U can't expect it here.Allergo is a good choice but still use it with bit care 

PS:Allergo also may system worse,if u don' handle with care..So use it carefully myschoolbucks