For a distributed DC microgrid, the conventional voltage control highly relies on the accuracy of the voltage observer, and the observer will produce an estimation error under time delays. To address the problem brought by the voltage observer, this talk adopts the PI consensus algorithm to design the optimal control and thus ensure the control accuracy will not be affected by the time delay. Moreover, it introduces scattering transformation to further improve the system stability. The effectiveness of the proposed control strategy and the transformation with and without time delay has been verified.