Toward Online Topology Optimization And Active Power Generation Re-dispatching For Reducing Transmission Loss In Power Systems

Reducing transmission loss is significant for improving power transmission efficiency and saving energy.These methods can be classified into two categories: the power-injection-based methods and the network-topology-based methods,which alters network topology without adjusting any control variable or adding any auxiliary equipment.In this paper,we present a novel online two-stage method for reducing transmission loss in power systems while satisfying operational and engineering constraints of post-optimizing power systems.As the line switching method has been an online practice,Stage I of the proposed method presents another application of the online line switching method for reducing transmission loss.Stage II of the proposed method presents an online modified OPF as a back-up or follow-up method if much further transmission loss reduction is needed.It is well recognized that linear methods are usually fast but may not be sufficiently accurate while nonlinear methods are usually accurate but may not be sufficiently fast.Considering this,the proposed method is a hybrid of linear and nonlinear methods.In addition,to balance the speed and accuracy for online application,both stages of the proposed method are also composed of three stages: screening,ranking,and detailed analysis.The stage of screening aims at speedily screening out effective candidate transmission lines and generators for transmission loss reduction.The stage of ranking aims at quickly and accurately ranking the screened candidates according to their performance on transmission loss reduction.The stage of detailed analysis aims at exactly analyzing the effectiveness of top-ranked candidates on transmission loss reduction.Distinguishing features of the proposed online two-stage method is: It provides multiple high quality and low cost solutions(line switching with or without modified OPF),from which operators may choose a desired one for transmission loss reduction.It satisfies the operational and engineering constraints of post-optimizing(line switching with or without modified OPF)power systems.