As the interconnecting device connected digital simulation and physical equipment in power hardware-in-the-loop(PHIL)

power interface plays a decisive role in the PHIL simulation system. The DC voltage fluctuation caused by load disturbance on the physical side is one of the key problems of running a stable power interface. For this problem

in order to improve PHIL system stability

a DC voltage optimum control strategy based on current feed-forward control considering control delay and its feed-forward control parameters are given. According to active power balance of AC-DC converter side

a unified power interface AC-DC model is developed using the small signal analysis method. The effectiveness of the proposed control strategy is proved to inhibit DC voltage fluctuations in the case of small disturbance. A DC capacitance parameter calculating method is presented and the feed-forward control is proved effective in reducing the DC capacitance. Finally

simulations and experiments verify the effectiveness of the method. This work is supported by National Natural Science Foundation of China(No. 51277137).