COMPUTER-AIDED, REAL-TIME DATA ACQUISITION SYSTEM FOR OPERATION AND CONTROL OF REACTIVE POWER COMPENSATORS

Abstract

Reactive power appears in every AC system. Many loads consume not only active but also reactive power. The electric network itself consumes and produces reactive power due to its inductive and capacitive components. Transmission and distribution of electric power involve reactive power due to the series inductance of transformers, overhead lines and underground cables. Lines and cables also generate reactive power due to their shunt capacitance; this generation of reactive power is, only of significance at system high voltages. During the steady-state operation of an AC power system, the active power production must match the consumption plus the losses, otherwise the frequency will change. There is an equally strong coupling between the reactive power balance of the power systems and the voltages. Excess of reactive power in an area means high voltages, a deficit means low voltages. The reactive power balance of a power system also influences the active losses of the network, the heating of components and, in some cases, the power system stability. Contrary to the active power balance, which is a£fected by the generator only, a reactive power balance is affected both by the generators and by reactive devices, i.e. shunt reactive devices in a reactive power compensation method and series capacitors in line reactance compensation method. No special reactive compensation devices were used in the early AC power system, because the generators were situated close to the loads. As the network became more widespread, synchronous motors, small synchronous condensers and static shunt capacitors were placed for power factor correction.