Hand carry power bank/ USB cables as well are allowed to bring on the hand carry luggage ?
Yes You can carry them with you.
Yuuki, I don't know why you would, I would put that sort of stuff in my checked luggage. However seeming you asked, if you fall with in the size allowance, yes you can.
Lithium batteries are not allowed in checked baggage. They have to be carried on. I don't know if that is relevant.
My power bank was taken at the security check. It as in my hand luggage because at check in it was written it couldn't go at the checked bag This happen at Beijing airport but to get there from Portugal no one bothered me about it and it was on my hand bag.