The increase in integration of renewable energy sources (RESs) and reform of electricity system in Japan will increase generation uncertainty in power system. To handle the said uncertainty, the authors, in this paper, propose the novel voltage and reactive power management technology that can reduce the transmission loss and number of control of shunt devices and transformer taps thereby reducing the operating expenditure (OPEX). This paper introduces the Optimized Performance Enabling Network for Volt/var(Q) (OPENVQ) system for smart operation. The system comprises a look-ahead operational condition, an optimal power flow, a grid equipment control and an online voltage security assessment. To validate the performance of the OPENVQ system, a simulator has been developed that can handle multi-period operational conditions with time series data. Simulation results based on the IEEE 118-bus model show that a look-ahead operational condition is important for online optimization of voltage and reactive power management. Further, a new logic to reduce the number of control of shunt devices and transformer taps for managing grid voltage is evaluated.