Monitoring and control of voltage stability in power systems

This paper proposes a new technique in controlling voltage instability in power systems. This technique coordinates between the reactive power of excitation systems and that of static VAr compensators (SVCs). The method starts with the decomposition of system into several voltage control areas (VCAs). When a reactive power deficiency occurs in certain area, excitation systems respond first to supply the required reactive power by increasing reactive generation of synchronous generators to its upper limit. If more reactive power is needed within the specific area to recover voltage instability, an SVC will be inserted by a switching controller in order to achieve the reactive balance. This controller receives an actuating signal when the terminal voltage is still unsatisfactory. By this technique, it is possible to fully utilize the excitation systems reactive power, and to design economically sized SVCs to recover voltage instability. The application of the proposed technique on the New-England 39 bus system proves its efficiency in controlling voltage instability.