System voltage and reactive power control: a computer-assisted manual/automatic concept

The authors describe a new computer-assisted software concept for hierarchic control of voltages and reactive powers in the real-time operation of power systems. The concept uses the local and centralised control levels. The local level employs existing automatic or manually operated control devices on regulating resources. The centralised level applies a superimposed computer-assisted manual control, based on reactive optimal power flow, with a dedicated criterion function dealing with system economy and security. An adaptive system zoning is incorporated in the concept, aimed at the matching, inherently local, character of voltage/reactive power control.