Optimal Power Flow Solution to Voltage Collapse in a Deregulated Electricity Market

Oluseyi, P.O (2010)

A Thesis Submitted to the School of Postgraduate Studies, University of Lagos


The thesis addresses the fundamental means of overcoming the challenge posed by voltage collapse to the success of electricity market unbundling. As regards the record available from the recent deregulation and unbundling of the Generation and Distribution segment of the electric power system, it has become evidently necessary to investigate the best and optimal operating conditions under which the transmission system is expected to perform with respect to the high level of transactions expected to always take place on both sides of the latter. Moreover, it is quite devastating to note that voltage collapse has remained one of the unresolved riddles that are currently plaguing the power system operation and performance under the recent electricity deregulation and restructuring regime. There is a number of techniques for overcoming the voltage collapse phenomenon, one of them is the transmission expansion programme (TEP). But due to the developing economy’s limited financial resources to engage in extensive transmission network’s expansion, thus this method is not recommended for the achievement of a stable electricity supply. Hence, in this thesis, the idea of operating the existing network with special reinforcement of the physical structure by the Flexible Alternating Current Transmission System (FACTS) devices becomes a very attractive option to ameliorate the occurrence of voltage collapse. The resulting network is then subjected to multi-objective optimization approach using the improved Strength Pareto Evolutionary Algorithm (SPEA-2) to achieve the optimal operating features of the reinforced network. Consequent upon this, the valuable contribution of the FACTS devices to the reinforcement of the network against collapse is evaluated by predicting availability and unavailability of the composite power system using the concept of Fault Tree Analysis (FTA). In an attempt to showcase the influence of the method developed in this research work, simulation results are presented for both the IEEE-30 bus and Nigeria-26 bus systems. In the results exhibited, the IEEE-30 bus system depicts a standard system while it is studied in comparison with the Nigeria-26 bus system. The results portray Nigeria-26 bus system as a network in need of serious investment in dynamic compensating devices.