Boundary supply capability for distribution systems: concept, indices and calculation

This study proposes the concept, indices and calculation method of boundary supply capability (BSC), which is the first capability curve for distribution networks. BSC describes the supply capability of distribution networks under various loading conditions. First, BSC is defined as a total load of an operating point on the security boundary. The BSC set of all boundary points represents the overall capability of a distribution network; while the total supply capability is the maximum value in a BSC set. Second, a method is proposed to calculate the BSC and its related indices. This method consists of three steps: (i) obtain a set of boundary points by sampling, (ii) calculate the BSC value of each point, and (iii) analyse the BSC set and obtain the following information: sorted BSC curve, BSC proportion distribution curve, mean value, lower bound, upper bound and so on. Finally, extended IEEE-RTBS-BUS4 cases are used to illustrate the proposed concept and demonstrate the effectiveness of the proposed BSC method. It is demonstrated that BSC can describe the supply capability distribution of distribution networks under N − 1 security comprehensively.