I configured the system using negative votes. So when an user reaches a negative value of -80, this user was moved into banned group via promotion system. This has a problem. A group of users can take the control and can ban others users. This is due to reputation power has not max limit. I think that if everything is done anonymously, and an user don't know if he gets negative votes. And users don't know if they have power. And there is a max power value, this can be fine. So i would like a hidden reputation system with a top reputation.