hello
2000W for 1/2 hour = 1kWh or 1000W during 1h. This is a lot of energy to store in a battery (car battery’s soring usual 60Amp/h by 12V. This is not enough. Therfore often gas heaters are used to solve this problem.
I am a electric engineer and I doe not knop of switches that swith off when voltages rises (in homes). I think you mean that it trips when current goes up.
AC 1kVA (1000W) Voltage stabilisers can be found on the internet here: http://www.vguard.in/stabilizer/voltage-stabilizers/stabilisers.htm#AC and here:http://www.ashleyedison.com/products/ses-automatic-voltage-regulator.htm
As you can see it is nothing to carrying with you…