In this paper, we present a coordinated control method for wind turbine generator and energy storage system for frequency regulation with provable probabilistic guarantees in the stochastic environment of wind power generation. The regulation requirement is specified in the form of metric temporal logic (MTL). We present the stochastic control bisimulation function, which bounds the divergence of the trajectories of the stochastic control system and the diffusionless deterministic control system in a probabilistic fashion. We first design a feedforward controller by solving an optimization problem for the nominal trajectory of the deterministic control system with robustness against initial state variations and stochastic uncertainties. Then we generate a feedback control law from the data of the simulated trajectories. We implement our control method on a four-bus system and test the effectiveness of the method with a generation loss disturbance. We also test the advantage of the feedback controller over the feedforward controller when unexpected disturbance occurs.