Analysis And Optimal Decision-making Of Available Transfer Capability

Available transfer capability is an important parameter of the reliability and economic of atransmission system. The evaluation of available transmission capacity is a critical issue toenable optimized and coordinated utilization of the capacity of a power grid so as to maintainsecure and reliable operation. Given this background, after reviewing the transfer capabilitystudy history, the decision-making mechanism and calculation model from more general vieware studied in this thesis.First, an optimal power flow based chance constrained programming model for the optimalcoordinated decision-making of transmission capacity is developed, with the sum of thepower in the interconnection lines among different areas as the objective function and thesystem security limits as constraints, and hence in the maximum transmission capacity suchobtained an adequate amount of capacity margin has been retained. A stochastic load flowembedded multi-objective differential evolution algorithm is employed for solving thedeveloped optimization model. The IEEE118-bus system is served for demonstrating theessential features of the developed model and method.Next, to deal with the uncertainties associated with wind generation, so as to maintain thesecure and economic operation of a power system, two risk-controlling strategies, includingspecifying the smallest acceptable probability for power flow limits not violated and the totalgeneration purchasing cost limit not violated, are introduced into the available transfercapability calculation for enhancing the ability of the obtained available transfer capabilityscheme against security and economic risks. An optimal power flow based chance constrainedprogramming model, with security and economic risk control strategies taken into account, isdeveloped. In this way, the security and economic risks associated with the power flow limitand generation cost limit violations respectively are evaluated by the combined use ofcumulants and Gram-Charlier series. The IEEE118-bus system is also served fordemonstrating the essential features of the developed model and method.Finally, the mode of load growth in available transfer capability determination is putforward. The assessment of available transfer capability not only provides the value ofcriterion, but also identifies the weak parts of a power system. Up to now, the problems havenot been properly utilized in existing methods. Given this background, this thesis introducesvalue function into the assessment of available transfer capability. It can ensure the obtainedschemes to avoid the unreasonable load increasing mode and to provide adequate informationof bottlenecks. The performance of the proposed method is demonstrated by Guangdong provincial power system.