System and method for transitioning between fuel supplies for a combustion system

A system includes a turbine fuel controller (14). The turbine fuel controller (14) includes a purge control logic (40) configured to control a purge sequence of mixing an inert purge gas (36) with a first fuel (18) during a first fuel shutdown, wherein the purge sequence is configured to open a purge valve (34, 92, and 94) for the inert purge gas (36) before fully closing a fuel valve (26) for the first fuel (18).