Hello Retoradio: The power line noise is most commonly heard on the HF band 3 to 30 MHz, but I have seen small VHF 2 meter yagi beams work. The key here is to make sure the noise can be heard on the VHF 2 meter band, so that the yage can be used. Some power line noise does not radiate the noise on the VHF bands. But some noises do, its the way the power lines are arcing I believe. Maybe walking around with a 2 meter HT will indicate if its detectable.
Looking at the power line noise on a spectrum analyzer you can see the power line noise drop off in amplitude as the frequency increases. How ever that maybe a good thing allowing the noise to only be detected at short ranges, indicating the noise source. It seems every noise Radio Interference (RFI) is some how different.
The local power company here just drives around while listening to his AM radio in his truck on a clear frequency with no stations being heard to start the isolation process. Then they use a small dish with a audio amplifier to actually hear a arcing noise to isolate the noise.
The ARRL has books on RFI and such. Good luck. Please let us know what the fix is.
Jay in the Great Mojave Desert.... "Next Gas 150 Miles"