The power company probably doesn't want people "hanging out" in proximity to their equipment either. Report the problem to them, tell them you've had difficulty in getting the police to evict trespassers, and ask them to contact the police as well.

There are tens of thousands of laws on the books. It's hard to get the police to act on ones they aren't familiar with.

The suggestion to contact the city attorney is good too. They'll contact the brass at the PD, who will put out the word in shift briefings, and you'll have the constables straightening out your neighbors.