The intermittent wind power in a stand-alone microgrid power system may cause a serious problem of frequency fluctuation. Energy storage (ES) such as a battery, super capacitor, superconducting magnetic energy storage (SMES) etc., can be used to reduce the frequency fluctuation. However, ES is extremely expensive especially for developing countries. They still prefer to minimize the use of battery or apply cheaper technology to suppress the frequency oscillation such as controllable load. This paper proposes the design of robust PI controllable load to stabilize frequency fluctuation in a remote microgrid power system. The proposed controller is a conventional first-order PI controller. To guarantee the robustness of the proposed PI controller, an inverse additive perturbation is formulated as an optimization problem and a genetic algorithm (GA) is employed to tune and optimize the proposed PI control parameters. Simulation studies have been done to verify the performance and robustness of the proposed robust PI controllable load on remote hybrid wind-diesel power system against various disturbances and system uncertainties.