Study On The Transformer Economic Operation Mode And Its Optimal Switching Strategy In Electric Distribution Network

Transformers are widely used in power system. As for the wide distribution and frequent application, their power losses account for as much as 30% of the entire power grid losses, so the transformer economic operation is of great significance for the energy-saving of the entire grid.In general, the economic operation of transformer indicates that the transformer losses are minimixed through the economic operation mode selection and load adjustment under the same transmission capacity. Among them, the operation mode selection is not only the primary content of present study but also the focus of this paper. The economic operation mode is known as the minimum loss operation mode and the selection is achieved by dividing the economic operation zone. In the current related documents, the study on economic operation zone division method occupies an overwhelming majority. The switching movement at the critical load point is able to keep the substation running in economic mode so as to obtain energy-saving benefits. However the current shortcoming is that a large number of literatures are often limited in the division method. Economic operation zone can only provide the critical load points and associated operation mode but can not obtain the correspondence to moment. Therefore, relying solely on the economic operation zone, the actual operator can not always make clear that the one-to-one correspondence between switching movement and moment. Therefore, the operation zone can not guide the economic operation of transformer effectively. However, the division of economic operation zone is the basis of economic operation mode and its significance can not be ignored. The series modified studies in this dissertation start from the basis.This dissertation firstly make a comprehensive study and presentation on the economic operation zone division method, and on this basis, proposes a series of innovative content such as"the combination of load curve processing and critical point method","transformer switching costs and energy-saving benefits","transformer's periodic optimized switching strategy"and"transformer's optimized switching strategy when taking into account the impact of reactive power compensation"."The combination of load curve processing and critical point method"is mainly directed against various types of transformer economic operation zone division method and proposes the improved idea;"Transformer switching costs and energy-saving benefits"mainly discusses the transformer life loss and energy-saving benefits due to a switching movement, and provides the basis of calculating switching program's profits;"Transformer's periodic optimized switching strategy"puts forward the optimal switching strategy which can obtain the maximized profits in various switching programs in the next period and presents the computing theory based on genetic algorithm."Transformer's optimized switching strategy when taking into account the impact of reactive power compensation"considers the impact on the original load curve from the reactive power compensation capacitors and states the necessity of revising the previous switching strategy. The three innovative content as the thesis and innovation points of this dissertation have played a role of complement and improvement to the results of our predecessors and are of some reference significance in the energy-saving work of the distribution power grid.