Due to the integration of photovoltaic, it is an important issue to maintain the voltage profile in distribution systems. The installation of smart inverters which can control active and reactive power flexibly is effective to manage the voltage control, in particular, to mitigate the voltage increase when a heavy reverse power flow appears. In order to regulate the voltage fluctuation properly, the application of droop control strategy is one of practical ways. On the other hand, various voltage control equipment based on flexible AC transmission system (FACTS) devices are being installed in addition to the conventional equipment such as on-load tap-changes (OLTC). Therefore, the control parameters of the smart inverters have to be adjusted to realize a coordinated control between the smart inverters and the other equipment. In this paper, we have developed a decision method of the control parameters to optimize the control performance considering the cooperation with other devices and network reconfiguration.