Power systems are increasingly being more stressed due to the need for more power transfer over tie lines. The competitive environment of power markets has made utilities to deploy the maximum capacity of the transfer system to trade power with the neighbouring power pools. This has pushed power systems toward their stability margins. When huge amount of power is transferred over weak tie lines inter-area oscillations are likely to happen. Many incidents of power system instability due to low damped oscillations have been reported. The most common method to damp power systems’ low frequency oscillations has been the use of Power System Stabilizers () for a long time. Conventional have proved to be quite effective in damping local oscillatory modes but when it comes to damping of inter-area modes they seem to lack the desirable efficiency. This is mainly due to the low observability of inter-area oscillatory modes in local signals such as rotor speed deviations or generator’s power deviations. Flexible AC Transmission System (FACTS) devices were initially devised for mitigating power system’s steady state performance such as voltage regulation and power flow capacity increase. Later they proved to be efficient in damping power systems’ oscillatory modes. Considering all , FACTS and HVDC controllers there are lots of controllers in a typical power system. Coordination of these controllers is essential for their efficient performance. The conventional method for tuning different controllers in a power system is the linear sequential method (LSM) in which controllers are tuned and installed one after another considering a specific oscillatory mode to be damped by each single controller.The main shortcoming of the LSM is that controllers are tuned disregarding the effect of the next controllers. Installation of a new controller inevitably affects the performance of previously installed controllers and may decline the damping performance of a specific controller. Optimization based coordination of controllers has been proposed for amelioration of this drawback. In this method the optimum performance of all controllers of a system is sought through optimization of an objective function. The coordinated design of and TCSC controllers based on the optimization of a proper objective function using the Genetic Algorithms is presented in this thesis. Furthermore, since the controllers designed by the conventional linear methods suffer a lack of robustness by change in the system working point or in the presence of different disturbances, a wide-area controller based on the robust controller design method is presented in this thesis. The performance of the controller is then compared with the residue-based controller for verification of the robustness of the controller design. The results show that the controller designed by Keywords: Coordinated design of power system controllers, Genetic Algorithms based optimization, design, TCSC damping controller, Wide-area controller design for power systems.
