A Central VQC Method based on Target Voltage Control for Local Voltage Control Devices

Abstract

The authors have developed a new central VQC (Voltage Q(reactive power) Control) method that cooperates with local voltage control devices AVQC (Automatic V-Q Controller). Each AVQC, located at principal substations or power stations, brings bus voltage close to its target voltage independently by controlling the on-load tap changers and shunt capacitors and reactors status. Each target bus voltage is optimally determined through on-line optimal power flow calculation to minimize active power transmission losses in the bulk power grid. Using this central VQC method, efficient voltage control is realized in comparison with the conventional VQC since the target voltage is updated continuously in accordance with the current power grid state. The voltage control function employing the described method has been already implemented into the energy management system at Tohoku EPCO and has been in operation from 2004.
This paper presents the newly developed method for central VQC and its excellent performance through bus voltages behaviors at the real Tohoku EPCO power grid.