Safety Research in Typical Connection Models of Distribution System

A cluster of improved safety indices for the connection models in 10 kV distribution network is raised based on k(n-1+1) safety criterion. These indices apply to describe not only the security of radial connection mode but also ring-type connection mode, such as "N-1" connection, sub-liaison connection, 4×6 connection and so on. Among these indices, the severity index of faults depicts the adverse impact that all possible branch-faults exert on distribution system, while the factors, including the severity of fault, the situation of restoring power supply after faults and so on, are taken into account by the security index of connection mode which is used to reflect the overall security of connection model. It is verified that these improved safety indices have a certain practical value through the analysis and calculation of the typical connection modes in 10 kV distribution system.