Among the consequences of massive distributed generation development, voltage rise is a major concern. The local reactive power control laws considered to solve this issue might lead to voltage instability. In this context, the current paper proposes a methodology to study voltage stability of a distribution feeder hosting distributed generation. The approach relies on the construction of an equivalent discrete abstraction of the continuous transition system by bisimulation calculation. The stability of the system is assessed conducting a reachability analysis of the equivalent discrete abstraction. An illustrative application of the proposed approach to a real medium-voltage 124 buses network with a single distributed generator reveals unstable operating regions of the network and helps designing a measurement filter ensuring system stability without loss of rapidity.