VOLTAGE MONITORING CONTROL SYSTEM, VOLTAGE MONITORING CONTROL DEVICE, MEASUREMENT DEVICE, AND VOLTAGE MONITORING CONTROL METHOD

A voltage monitoring control system includes voltage control apparatuses controlling voltage on a power distribution line, a local voltage control device adjusting a voltage value controlled by the voltage control apparatuses such that it is maintained within a range between voltage upper-and-lower-limit values updated every first cycle, a voltage and power-flow measurement device calculating and transmitting fluctuation-band information indicating fluctuation band of the voltage every third cycle longer than a second cycle based on voltage on the power distribution line measured every second cycle shorter than the first cycle, and a centralized voltage control device. The centralized voltage control device includes a voltage-fluctuation-band calculation unit calculating fluctuation band within the first cycle, an optimal-voltage-distribution determination unit determining a threshold value for allowance for each of upper and lower limits of an appropriate voltage range and acquiring an optimal control amount, and a voltage upper-and-lower-limit-value determination unit.