A self-adaptive strategy for the last breaker in UHVDC project based on graph theory is put forward. An equivalent model of the AC field and a solving model of the last breaker based on graph theory are set up. With the AC field abstracted as an undirected connected graph

the breaker as the edge of the graph

AC line

converter and other equipments as the nodes of the graph

the solving problem of the last breaker is converted to a cut edge calculation problem of the undirected connected graph

making the process of last breaker calculation fast

accurate and intelligent. The implementation of the strategy in a project is expected to have great significance for the stable operation of the power grid.