A novel fuzzy logic secondary voltage controller

A novel fuzzy logic secondary voltage controller based on polar fuzzy logic rule is designed in this paper. The controller uses the voltage of the pilot node as a feedback signal and adjusts voltage level of the pilot node through the excitation control with the rules of fuzzy logic. The parameter regulation, performance and principle of the controller are briefly analyzed. The controller effectively combines fuzzy logic rule with secondary voltage control: the voltage error of pilot nodes and its differential are the front input of a fuzzy logic block. The regional voltage control signal is generated after a PI block, whose input is the voltage control signal which is obtained by the fuzzy logic rule. By using participant factor the generators´ reactive power output in an area can be coordinated with each other. Numerical simulation is carried out on the New England 39 node system. Simulation of small disturbance on load shows that the fuzzy logic controller can restore the voltage level more rapidly than conventional controllers. When load increases slowly, the test system with fuzzy logic secondary voltage controller has a better voltage level and a larger steady voltage stability margin than those with conventional secondary voltage controllers.