This paper presents a frequency control strategy for networked micogrids. Applying a hierarchical control structure, the usual droop-control for AC microgrids is replaced by a droop-free paradigm that acts as a first and second level control. To control the frequency of the networked microgrid system, a third control level is introduced to control the frequency for the whole system in a distributed way, following the same structure of the droop-free paradigm, such that power sharing and frequency regulation is achieved.