The wind-photovoltaic (PV)-storage hybrid system exhibits potential as a black-start power source to expedite system restoration. To mitigate the transient voltage drop caused by auxiliary machine activation during black start, a coordinated voltage control strategy is proposed for auxiliary machine start-up in thermal power plants using a wind-PV-storage hybrid system. A voltage control framework is established, integrating model predictive control (MPC) to dynamically coordinate reactive power outputs of wind turbine generators (WTGs), energy storage systems (ESS), and PV units. Voltage regulation is categorized into normal control mode and corrective control mode, with optimization models formulated to generate active/reactive power sequences. Simulations in MATLAB/Simulink validate the strategy under two cases. The results demonstrate that the proposed strategy reduces voltage sags by 16.7% and accelerates the recovery speed compared to traditional wind-storage methods.