This paper proposes a coordinated frequency control scheme for emergency frequency regulation of isolated power systems with a high penetration of wind power. The proposed frequency control strategy is based on the novel nonlinear regulator theory, which takes advantage of nonlinearity of doubly fed induction generators (DFIGs) and generators to regulate the frequency of the power system. Frequency deviations and power imbalances are used to design nonlinear feedback controllers that achieve the reserve power distribution between generators and DFIGs, in various wind speed scenarios. The effectiveness and dynamic performance of the proposed nonlinear coordinated frequency control method are validated through simulations in an actual isolated power grid.