This paper considers the power sharing problem for a grid-connected AC microgrid consisting of multiple dispatchable distributed generators. The microgrid is modeled as a multi-agent system and the power sharing problem is formulated as an interconnected leader-following consensus problem in the sense that the leader is affected by the fol- lowers passively. To solve this interconnected leader-following consensus problem, a distributed control scheme is proposed. First, each distributed generator is equipped with a distributed observer to communicate with each other and agree on a global reference signal, based on which the local reference power output is determined in proportion to its power capacity. Second, local tracking controller is designed for each distributed generator to achieve local reference power output tracking. It is proven that, under this control scheme, power sharing among all the distributed generators can be accomplished autonomously. Simulation results are presented to validate the effectiveness of the proposed control scheme.