Help required to fix the sampling rate of ADC in an Energy meter project

I have started to implement a energy meter in Arduino platform,and now I have struck the first brick wall:
I want to sample the AC line voltage and current from a stepdown transformer and current sensor to calculate the instantaneous power/energy. But the problem is I want to take a large no. of samples over a cycle(say 200).So I want a sampling speed of 200x50Hz = 10000 Samples/second (I am from India). From the datasheet of Atmega328 I found that the sampling speed can go upto 15 kSPS(at max. resolution) so I think it is achievable much possible. But I am not achieving that much speed with the AnalogVoltageSerial example sketch(I am recieving 6 samples/cycle = 300samples/second). I am a newbie at Arduino platform please help.

Please read the forum guidelines and post your code, using the # button.

However, I will bet you are printing each ADC value to the serial monitor as you get it. Don't. Printing takes time.
Instead, create an array and simply store the ADC values for later analysis.

Thanks for the reply jremington. I will get back with more details.

You my find this link useful


Thanks to all the problem is pretty much solved. @Robin2 it is a useful link indeed.