This paper presents the design of the advanced voltage management system (AVMS) including manual operation mode in order to control reactive power generations in practical power system. The existing secondary voltage controller (SVC) has a demerit occurring large transient phenomenon shortly after the SVC begins to work. This malfunction results from the difference of the operation status before and after the SVC operates. For solving the problem and implementing the voltage control safely, the AVMS including the manual operation mode is developed by Korea Electric Power Corporation (KEPCO). As well as the AVMS overcomes the drawback, it can execute the coordination control of both continuous voltage controller (CVC) and discrete voltage controller (DVC). The CVC controls reactive power generation sources such as generator and FACTS devices which can generate reactive power continuously and linearly. Otherwise, the DVC controls the discrete reactive power sources such as switched shunt capacitors and reactors. The performances of the proposed AVMS are carried out by time domain simulation in the Jeju Island power system with real-time digital simulator (RTDS).