An optimal fuzzy-logic controller of a FACTS device for damping oscillations in power system with wind generation

An optimal controller for a shunt-connected FACTS device has been developed for enhancing the dynamic performance of a power system with wind power generation in a wide range of transient conditions including wind gusts. The FACTS device considered is based on the Static VAr Compensator (SVC) with fuzzy-logic control which complements the voltage control function to provide system oscillations damping. A constrained-optimization design procedure for determining the optimal values of the linguistic variables for forming the crisp output of the fuzzy-logic controller has been developed. A novel aspect of the design is to establish the nonlinear relationship between the linguistic variables and the power system dynamic performance index (DPI) formed from the variations in wind-turbine induction generator voltage, slip and output active power. The nonlinear relationship is represented by a multilayer feed-forward neural network. The inputs to the neural network are the linguistic variables associated with the controller output, and the neural network output represents the DPI. The objective function defined in terms of the DPI is minimized with respect to the linguistic variables, constrained within their bounds, to give their optimal values. Time-domain simulations illustrate the effectiveness and robustness of the optimized fuzzy logic-controlled SVC in a wide range of operating condition.