Power system small-signal stability as affected by grid-connected photovoltaic generation

This paper investigates the impact of a grid-connected large photovoltaic (PV) power generation station on the power system small-signal stability. The focus of discussion in the paper is the damping of local-mode power system oscillations. Hence, a simple single-machine infinite-bus power system with the grid-connected PV generation station is used. Firstly, a comprehensive model of the single-machine infinite-bus power system integrated with the PV generation station is established. Then the conventional technique of the damping torque analysis is employed to examine the effect of the PV generation on the damping of power system local-mode oscillations. Analysis in the paper reveals that there exists a critical operating condition when the damping torque contribution from the PV station to the electromechanical oscillation loop of conventional generator changes sign. Hence, the small-signal stability of the power system can be affected negatively by the PV penetration when it operates beyond the critical operating condition. In the paper, an example power system is presented. The results of numerical computation and non-linear simulation demonstrate and confirm all the analytical conclusions obtained. Copyright (C) 2011 John Wiley & Sons, Ltd.