This thesis examines the problem of load flow feasibility, in other words, the conditions under which a power network characterized by the load flow equations has a steady-state solution. In this thesis, we are particularly interested in load flow feasibility in the presence of extreme contingencies such as the outage of several transmission lines. / Denoting the load flow equations by z = f(x) where z is the vector of specified injections (the real and reactive bus demands, the specified real power bus generations and the specified bus voltage levels), the question addressed is whether there exists a real solution x to z = f( x) where x is the vector of unknown bus voltage magnitudes at load buses and unknown bus voltage phase angles at all buses but the reference bus. Attacking this problem via conventional load flow algorithms has a major drawback, principally the fact that such algorithms do not converge when the load flow injections z define or are close to defining an infeasible load flow. In such cases, lack of convergence may be due to load flow infeasibility or simply to the ill-conditioning of the load flow Jacobian matrix. / This thesis therefore makes use of the method of supporting hyperplanes to characterize the load flow feasibility region, defined as the set the injections z for which there exists a real solution x to the load flow equations. Supporting hyperplanes allow us to calculate the so-called load flow feasibility margin, which determines whether a given injection is feasible or not as well as measuring how close the injection is to the feasibility boundary. This requires solving a generalized eigenvalue problem and a corresponding optimization for the closest feasible boundary point to the given injection. / The effect of extreme network contingencies on the feasibility of a given injection is examined for two main cases: those contingencies that affect the feasibility region such as line outages and those that change the given injection itself such as an increase in VAR demand or the loss of a generator. The results show that the hyperplane method is a powerful tool for analyzing the effect of extreme contingencies on the feasibility of a power network.

This thesis has mainly focused on investigating the effect of communication network on the power system operation. The main objective of this research has been to develop a set of communication network simulation tools and verify their suitability for realistic cosimulation of a power system and an associated data-communication network within a power system simulation environment. Based on a background study, a set of communication components have been developed for the PSCAD/EMTDC power system simulation software, which can simulate communication delay and packet losses. Furthermore, an analytical method based on queuing theory has also been developed to evaluate the communication delay and packet loss probability of a typical PMU-PDC communication network. Finally, the communication components developed in this thesis have been integrated into the simulation of a wide area power system application to investigate the effect of communication network parameters on the power system operation.

In North American utilities, control area performance of interconnected power systems is assessed by the reliability standards imposed by the North American Electric Reliability Corporation (NERC). NERC standards on control area performance define two indices known as Control Performance Standards 1 and 2 (CPS1 and CPS2) to evaluate control area performance in normal interconnected power system operation. Out of the two indices, CPS1 evaluates the performance of a control area with respect to control of interconnection frequency and tie-line power flows. This thesis proposes a novel method to approximately estimate CPS1 for a two area power system using the probability distribution of load change. The proposed method of estimating CPS1 is validated against the time domain simulation method using a simple two-area test system. In the validation process, it is shown that the proposed method could approximately forecast CPS1 within 5% accuracy. The forecasted CPS1 value could then be used by a control area to design its future control strategies to be in compliance with NERC criteria at the minimum cost. These control actions include, but not limited to tuning governors, reducing non-confirming loads, ensuring adequate operating and spinning reserves etc.

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