Two kinds of security distance for distribution network

This paper focuses on the security distance for distribution network. Security distance for distribution network is the distance from the operating point to the security boundaries. Firstly, two kinds of security distance are defined, including geometric security distance (GSD) and feeder security distance (FSD). GSD is the distance from an operating point to the effective security boundary in the geometric space; FSD is the distance to the effective security boundary along the coordinate axis. Secondly, security assessment methods based on different security distance definition are discussed. It is shown that GSD can provide conservative margin of load while FSD provides accurate load margin. Finally, the load margin results based on GSD and FSD are shown in a real case study. This research is helpful for a better understand of the security distance for distribution network, in which the security distance is more efficient for online security assessment application.