1. Key Laboratory of Smart Grid of Ministry of Education(Tianjin University), Tianjin 300072, China; 2. State Grid Beijing Electric Power Company, Beijing 100031, China; 3. Beijing Electric Power and Economic Research Institute, Beijing 100055, China

This paper proposes a total supply capability(TSC)model and the solution algorithm for flexible distribution network(FDN). Firstly, FDN is defined as a distribution network, which operates in closed loop with flexible control of power flow when multiple feeders are linked together by a flexible switching station(FSS)composed of electronic switches. Secondly, the model and the solution algorithm of TSC for FDN are proposed, the model based on a new flexible load transfer strategy. Finally, the proposed model and solution algorithm are tested through a typical FDN in different scenarios. The test result is compared with the traditional TSC model, showing that TSC will either increase or remain unchanged when a traditional grid is upgraded to FDN, the reason for which is analyzed. The advantages of FDN seen from the aspect of TSC are as follows. On one hand, the TSC is easier to achieve in the FDN since the load can flexibly be distributed in the system. In contrast, only when the load is distributed in a certain specific way, can the traditional distribution network achieve TSC. On the other hand, the network configuration of FND is more concise than that of traditional distribution network with the same TSC. The proposed method has been applied in the argumentation of the first domestic demonstration project of multi-terminals flexible closed-loop medium-voltage distribution network.