Analysis and Improvement on the Small-Signal Stability of a Multimachine System with High Proportion Photovoltaic

With the increasing proportion of PV (photovoltaic) power generation connected to the power system, there are large quantities of outstanding problems in low-frequency oscillation that cannot be ignored. In this paper, an equivalent aggregation module of large-scale PV and a PMT (Plug-in Modeling Technology) module of a multimachine power system with PV is established first. Then, the eigenvalue analysis method is adopted to analyze small-signal stability on low-frequency oscillations of the entire power system before and after PV replaces the synchronous generator and PSS (Power System Stabilizer) participates. The root locus method is adopted to discuss the change in eigenvalues and damping ratios of a multimachine power system with a high PV percentage when the parameters of the PV converter are changing. The results indicate that the damping ratio of the system oscillation mode is reduced by replacing the synchronous generator with PV, and the greater the replaced generator is involved in the original mode, the more drastic the change is; At a low ratio, the participation of PSS can enhance the stability of the power system with PV; At a high ratio, the stability can be improved by appropriately adjusting the parameters of the outer voltage controller loop and phase locked loop.