Stability improvement by contingency constrained optimal reactive power flow and linear matrix inequalities

This thesis presents results of designed preventive control strategy that enhances voltage stability and increases post-contingency loadability limit (PCLL) for a set of critical contingencies. The operating point is determined using a contingency constrained optimal reactive power flow (CCORPF) in which the cost function reflects the proximity of the reactive power generation to its limits at critical buses, both in the base case and for selected contingencies. Results obtained for the IEEE 39 bus system are provided to demonstrate the effectiveness of the designed method.; A further enhancement of the system performance involves the application of linear matrix inequalities (LMI) in the context of robust decentralized mechanical and exciter control of electric power systems. A new LMI-based mechanical control accounts for unpredictable equilibrium shift due to load fluctuations, faults and topological changes. The designed robust decentralized exciter control is computationally attractive and the resulting feedback is linear, which allows for easy implementation. Experiments on the IEEE 39 bus system demonstrate that these controls are robust with respect to the fault location and to variations in the system operating point.