On the dynamics and statics of power system operation : optimal utilization of FACTS devices and management of wind power uncertainty

Abstract

Nowadays, power systems are dealing with some new challenges raised by the major changes that have been taken place since 80’s, e.g., deregulation in electricity markets, significant increase of electricity demands and more recently large-scale integration of renewable energy resources such as wind power. Therefore, system operators must make some adjustments to accommodate these changes into the future of power systems. One of the main challenges is maintaining the system stability since the extra stress caused by the above changes reduces the stability margin, and may lead to rise of many undesirable phenomena. The other important challenge is to cope with uncertainty and variability of renewable energy sources which make power systems to become more stochastic in nature, and less controllable. Flexible AC Transmission Systems (FACTS) have emerged as a solution to help power systems with these new challenges. This thesis aims to appropriately utilize such devices in order to increase the transmission capacity and flexibility, improve the dynamic behavior of power systems and integrate more renewable energy into the system. To this end, the most appropriate locations and settings of these controllable devices need to be determined. This thesis mainly looks at (i) rotor angle stability, i.e., small signal and transient stability (ii) system operation under wind uncertainty. In the first part of this thesis, trajectory sensitivity analysis is used to determine the most suitable placement of FACTS devices for improving rotor angle stability, while in the second part, optimal settings of such devices are found to maximize the level of wind power integration. As a general conclusion, it was demonstrated that FACTS devices, installed in proper locations and tuned appropriately, are effective means to enhance the system stability and to handle wind uncertainty. The last objective of this thesis work is to propose an efficient solution approach based on Benders’ decomposition to solve a network-constrained ac unit commitment problem in a wind-integrated power system. The numerical results show validity, accuracy and efficiency of the proposed approach.