Abstract: The integration of different types of solar power plants and energy storage systems is an innovative option to mitigate the impacts of the variability and intermittency of solar energy. In this paper, a coordinated control strategy of the hybrid PV/CSP plant during symmetrical voltage sag is proposed. First, the simplified mathematical model of the plant is developed. Moreover, the power control of inverter based on the synchronous reference frame is presented to guarantee satisfactory performances of reactive power and voltage outputs of PV due to the depth of sag. Meanwhile, an improved AVR-PSS based on nonlinear PID is established to not only enhance the terminal voltage transient stability and damping oscillations, but also improve the dynamic response and robustness of the system, compared with the traditional control method. The simulation results based on Matlab/Simulink show that the proposed control strategy can support voltage recovery effectively when the grid voltage drops and realize low voltage ride through capability on the basis on the grid code.