Abstract: As to the potential inter-area low-frequency oscillation problem of power system with grid-connected large-scale photovoltaic (PV) power plants, wide-area damping controller (WADC) for large-scale PV power plants is proposed based on correlation identification method. Firstly, the open loop transfer function of the system is obtained by correlation identification method based on pseudo random signals. Then TLS-ESPRIT(total least squares- estimation of signal parameters via rotational invariance techniques, TLS-ESPRIT) method is applied in calculating dominant mode ratio (DMR) to select the optimal input signal of WADC by combining residue index. Secondly, the parameters of WADC are regulated by using pole placement method. Finally, the electromechanical transient model of two-area system with grid-connected PV power plants is built by DIgSILENT/PowerFactory. The time-domain simulation results show that PV WADC for power system with grid-connected large-scale PV power plants can effectively control inter-area low-frequency oscillation, and improve the small signal stability of power system.