This is PQL related question: how do I filter out nodes that are powered off? In PE console their status connected is set to no.

There are a few options. I don't think PuppetDB saves the pxp-agent connection state. but you could filter when their last report happened. Does that help? We've some examples at https://voxpupuli.org/docs/pql_queries/#get-a-list-of-nodes-with-stale-catalogs-date--r-to-see-your-time-offset (if you come up with something new, please let me know or provide a PR for those docs)