The uncertainty and intermittent characteristics of the output of new energy power sources make the output of grid-connected power sources change frequently. The self-excitation problem may occur in the process of black-start, which is one of the key factors to decide whether the black-start restoration scheme is feasible or not. Through theoretical research and simulation analysis, this paper discusses the criterion of hydropower self-excitation in the local power grid, and studies the effect of self-excitation on the system when different black-start schemes are formulated.