Maintaining a close balance between power generation and demand is essential for sustaining the quality and reliability of a power system. Currently, due to increased renewable energy generation, frequency deviations and power fluctuations of greater concern are being introduced to the grid, particularly in regions that are weakly interconnected with their surrounding areas, such as small islands. This paper addresses the problem of frequency control in isolated power systems with relevant inclusion of wind power generation. With this aim, we have analyzed the contribution of the demand side to the primary frequency control together with an auxiliary frequency control, which is carried out by variable-speed wind turbines through an additional control loop that synthesizes virtual inertia. We have evaluated both the suitability of these two additional control actions counteracting frequency deviation and their potential reserves and compatibility. The results indicate a substantial improvement in both the dynamic performance and grid frequency stability. Simulations also indicate a decrease in the steady-state frequency error, which may relieve the secondary frequency control.