Research On Power Grid Partition Methods Based On Short Circuit Current Calculation Of The Equivalent Model

Along with the development of the power system in our country,the economic developed areas of load density and large capacity units continue to increase.Low impedance large-capacity transformer is widely used in grid planning and power grids are increasingly interconnected.The grid structure is also strengthened on the basis of improving the power transmission capacity of the interregional power grid to ensure the safe and reliable operation of the power grid.The negative effects of power construction and development are the sharp increase of short circuit current.Short circuit current overweight problem has become one of the main problems which restrict the development of the power grid.Based on the grid equivalent model calculation this paper proposes a partition operation method,which provides reference for grid partition scheme.Firstly,this paper analyses the reasons of the short-circuit current increase and the main comprehensively restrictions of power grid.Grid partition planning is the basic method to reduce the overall level of short circuit current.The main method of limiting short circuit current of power network is to realize partition operation of existing lattice structure;The general procedure of short circuit current calculation and the basic flow of short circuit current are analyzed in detail,equivalent model for power grid short-circuit current calculation provides a theoretical basis.And then the paper studied the grid short-circuit current calculation method of equivalent model based on the analysis of load density maximum power grid,including Beijing and Shanghai.The typical partition scheme of 500 kV single-station feed model,two-station partition model and three-station partition model is summarized.In the process of the establishment of the model,the key factors influencing short circuit current are fully considered,such as the length of the link between substations,partition inside factors,power supply capacity and distribution.The short circuit current of equivalent model is close to the actual short circuit current.Finally,the 2018 level for the Tangshan grid partitioning scheme are researched on the basis of understanding the operation condition of Tangshan power grid.The analysis of the short-circuit current limitation scheme includes TangCheng analysis and the expansion project of the 500 kV substation.By comparing the actual partition results with the equivalent model,the correctness of the calculation method of short-circuit current of the equivalent model is verified.