Research On Delamination And Partition-area Operation And Its Stability Of Regional Power Grid

With the rapid development of national economy,people’s living standards improve rapidly and residents’ demand for electricity consumption also grows rapidly.It is often the case that the transmission capacity of regional power grid cannot meet the demand for electricity.The traditional solution is to build transmission lines of higher voltage grade to achieve the purpose of increasing transmission capacity.In this way,the high and low voltage transmission lines run in parallel through the two ends of the transformer,forming a high and low voltage electromagnetic loop network.In the early stage of power grid development,due to the imperfect grid structure,it is reasonable to use electromagnetic loop network.With the development and construction of the power grid entering the mature stage,the system grid structure can be strengthened.At this time,the existence of electromagnetic ring network will bring some disadvantages to the power system.Here are some of the disadvantages.When a transmission line fails,it will cause the line’s stable transmission limit to exceed the limit,which will cause system shock.The short-circuit current level of the system may be increased.The distribution of power flow in the system is unbalanced and difficult to control.When the power flow is transferred,it is easy to cause voltage sags.Therefore,it is necessary to open the electromagnetic loop network at a proper time in order to to achieve the hierarchical and regional operation of the regional power grid.Firstly,this paper takes the actual power grid as an example,adopts the power grid partitioning method based on load current field to conduct layered partition for the power grid in a certain region in 2025.According to different disconnection options,various layered partition operation schemes are developed.Building a simulation model to calculate the static operation index of each scheme by using PSD-BPA software.After comprehensive analysis and comparison,the optimal scheme of regional power grid hierarchical and zonal operation is determined.Then,from the perspective of transient power angle stability and transient voltage stability,the system transient stability before and after the regional power grid hierarchical operation is analyzed,and the rationality and feasibility of the power grid hierarchical operation scheme are verified.Finally,a decision evaluation system of 500 k V substation layout based on hierarchical zoning is proposed.In consideration of the influence of the layered and zoned operation of the power grid on the system,nine representative indicators are selected from the four aspects of economy,static safety,short-circuit current level and voltage stability,and the decision-making evaluation index system is established.According to the regional power grid development planning,the regional power grid in 2030 under the two feasible 500 k V substation layout methods should be stratified and zoned,and four stratified zoning schemes should be formulated.The TOPSIS-GRA method was used to evaluate the decision of each scheme.By calculating the relative closeness degree of each scheme,the layout mode of 500 k V substation in the regional power grid was optimized,and the regional power grid operation plan of stratified and zoning in 2030 was finally determined.