Coordinated voltage control using fuzzy logic

This paper describes a knowledge-based system for supervision and control of regional voltage profile and security using fuzzy logic. The control strategies are defined by system operators based on their experience and on offline studies, which are translated into rules of a hierarchical fuzzy inference system (FIS). Two hierarchical levels, namely, task-oriented control level (high level) and set-point control level (low level) compose the control structure. The high level control is comprised of a continuous FIS that updates high-side voltage set points at power plants, and a discrete FIS that switches capacitor/reactor banks at the transmission network. The low level control is comprised of automatic voltage regulators (AVR) and joint VAr controllers (JVC) at the power plants.