Grid Mode Optimization Selection Of Local Power Grid And Energy Base DC Sending System

With the implementation of the "The Belt and Road Initiative" and the "The Global Energy Internet" strategy,A large number of energy base DC delivery projects are put into operation to achieve efficient use of clean energy.These energy bases generally have large installed capacity and are remotely located away from the receiving end of the main network.They are usually sent directly to the receiving end through the DC delivery system.In recent years,due to economic interests,the local power grid near the energy base has the need to be integrated into the energy base delivery system.However,the size of the grid in these places is small,and the structure is weak.When connected to the DC system,the operation state of the DC system is complicated,and the problem of relatively serious voltage stability at the sending end is prone to occur.Therefore,it is necessary to rationally optimize the grid mode for DC sending system to meet the technical and economic requirements of all parties in the AC and DC systems.Based on this new problem,this paper takes the local grid and energy base DC delivery system as the research object,and proposes the optimization method of grid mode.The main work is summarized as follows:Aiming at the problem of optimal selection of grid mode for DC sending system of local power grid and energy base,this paper establishes a model of DC delivery system for local power grid and energy base.The problems of isolated-connected and gird-connected modes are analyzed,and the effects of factors such as technology,economy and development scale are considered.A set of quantitative evaluation indicators based on static security,transient stability,economy and development scale indicators are constructed.The system paves the way for the optimization of the selection method of the grid mode.In order not to lose generality,on the basis of the above comprehensive evaluation index system,the general evaluation index matrix is first promoted.Then,considering the subjective and objective factors,the combination weight of the evaluation indicators is reasonably selected,and a method for optimizing the grid mode of the local grid and energy base DC sending system based on the relative closeness is proposed.And then,through the simulation analysis of the example,the optimal selection results of the proposed method and the traditional analytic hierarchy process are compared,and the superiority and rationality of the proposed method based on relative closeness optimization are verified.Because the specific calculation process of the above method is complicated,it is only suitable for the occasion of accurate calculation,and cannot meet the requirement of quickly optimizing the selection of the grid mode.Furthermore,this paper proposes a method of grid mode optimization selection based on gray correlation degree,which can make full use of the objectivity of data and meet the needs of rapid optimization of selection mode.At the same time,the rationality of the method is verified by simulation analysis.Finally,the optimal selection results of the method are compared with the traditional analytic hierarchy process and the optimal selection method based on the relative closeness optimization method,and the applicability of different methods is illustrated.