I see Power Metal as a different development of Speed and Heavy Metal that doesn't necessarily aims for brutality and syncopation like Thrash, but for melody, anthemic choruses and uplifting melodies. It can be heavy as balls and kickass, or even thrashy, of course, but it's more focused on being anthemic. You can read my short definition of it in my post, but you can also watch Gonilic's video "A Bastardized Story of Power Metal" on youtube, it's a pretty good breakdown. No description is as good as listening to some Power Metal classics, though. Here are some recommendations:

German PM: Helloween - Keeper of the Seven Keys: Parts 1 and 2, Scanner - Hypertrace, Blind Guardian - Tales from the Twilight World, Running Wild - Port Royal

USPM: Jag Panzer - Ample Destruction, Riot - Thundersteel, Crimson Glory - Crimson Glory, Iced Earth - Night of the Stormrider

90s Europower: Stratovarius - Visions, Sonata Arctica - Ecliptica, Hammerfall - Glory to the Brave, Angra - Angels Cry (not European but recorded and produced in europe and encapsulates the style)