This thesis studies the dynamic-stability improvement of a multi-machine system connected with a large-scale offshore wind farm based on doubly-fed induction generator (DFIG) using a generalized unified power-flow controller (GUPFC). A two-area four-generator system model is employed as the studied multi-machine system. Two proportional-integral-derivative (PID) damping controllers and two fuzzy logic controllers (FLCs) of the proposed GUPFC are respectively designed to improve the stability of the studied multi-machine power system connected with the offshore wind farm under different operating conditions.
A frequency-domain approach based on a linearized system model using eigenvalue analysis and a time-domain method based on nonlinear-model simulations subject to various disturbances are both performed to examine the effectiveness of the proposed GUPFC combined with the designed damping controllers.
It can be concluded from the comparative simulation results that the proposed GUPFC joined with the designed FLCs demonstrates better damping performance for improving the stability of the studied multi-machine system subject to different disturbances than the designed PID damping controllers.

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