The emerging of renewable distributed energy resources (DER) in the residential community opens the door to forming a residential community microgrid. However, traditional microgrid controls via the hierarchical feedforward tertiary, secondary, and primary control framework may not be effective for such residential community microgrids, because of high volatility, low inertia, and insufficiency of DERs. This paper discusses an online feedback scheme, which cooperates the three control layers in real time to improve operational stability of the microgrid. In addition, to economically dispatch scarce reserve, this paper deduces an increment cost model of battery storage assets based on their degradation costs and depth of discharges. The model is of low computational complexity, thus can be naturally embedded in the proposed online cooperative feedback control scheme to calculate marginal price in real-time. Small-signal analysis and Simulink simulation are conducted to illustrate the performances of the proposed online cooperative feedback control scheme.