Static Security Analysis Of City Power Grid Based On Global Power Supply Capability

City power grid is an important link in ensuring reliable supply of power withinurban areas, so the security analysis concerning city power grid has always been the focusof the research of domestic and abroad scholars. City power grid is a global system whichcontains transmission and high-voltage distribution network; there are connectionrelationship of structure and electrical energy between transmission and high-voltagedistribution network. Traditional security analysis of power grid generally separates thetransmission and distribution network, which leads to limitation of the analytical results.Under the circumstances, from the points of grid structure and load margin, this paperconducts some research on global security analysis of city power grid. The main contentsare as follows:Firstly, based on N1contingency analysis and safety power supply capability, thispaper analyzes the security of transmission grid. For circuit failure, this paper analyzes thestate of transmission grid through sensitivity analysis method; For generator failure, anoptimized mathematical model of power increment of normal generator is establishedthrough the objective function of minimum equilibrium degree of power flow to reducesecondary risks caused by power flow transferring; For grid satisfying any N1contingency analysis, combined with linear programming method and improved powerflow calculation model, safety power supply capability of transmission grid is calculated.Then, this paper establishes security analysis index of load loss, power flow overloadand load margin. On this basis, a static security analysis model of transmission grid isestablished. The simulation result confirms that this model can not only identify potentialsafety risk, but also determine distance between current operation status and safe operationstatus.Finally, the global security of city power grid is analyzed from the point of globalmaximum power supply capability. According to the structure and load characteristics ofhigh-voltage distribution grid, this paper establishes a maximum power supply capabilityanalysis model of high-voltage distribution grid, which is based on demand side analysis; combined with safety power supply capability of transmission grid, the power congestionis analyzed to calculate the global maximum power supply capability of city power grid.The research on the relationship between actual load and global maximum power supplycapability can effectively locate weak link in operation and provide reference data forglobal security analysis of city power grid.