High degree penetration of residential rooftop PVs in traditional distribution networks would cause overvoltage problem. In recent years, home appliances such as heat pump are considered to be utilized for voltage control [1]. The authors are developing a new structure of multi-community energy management systems (CEMSs) for overvoltage prevention control [2]. In this paper, a coordinated real-time overvoltage prevention control of on-load tap changer transformer (OLTC) and multi-CEMSs is proposed. The main objective of this control is to relieve the OLTC tap operation stress by scheduling the operation of loads while maximizing the profit of customers in each CEMS.