Improvement of LVRT behavior of Variable Speed Pumped Storage Units to enhance the transient stability of the power system: A Case Study

However, practical engineering deployment of VSPSUs, especially large-capacity units, remains limited. In particular, the mechanism by which the dynamic behavior of VSPSUs influences the power angle stability of adjacent Invariable Speed Pumped Storage Units

(ISPSUs) has not yet been fully clarified. To address this issue, this paper investigates a typical engineering case from the Yongli Pumped Storage Power Plant (PSPP). Based on the

Equal Area Criterion (EAC), it is shown that a slower active power recovery rate or sustained reactive power support during the low-voltage ride-through (LVRT) process of ISPSUs can enhance transient stability by enlarging the deceleration area. Furthermore, parameter retuning methods are proposed to improve the LVRT performance of VSPSUs and thereby strengthen system stability. Simulation studies based on the Yongli PSPP validate the effectiveness of the theoretical analysis and the proposed parameter optimization methods.

Specifically, in the Yongli PSPP project, application of the proposed methods increases the transmission capacity by up to 200 MW and is estimated to raise annual renewable energy consumption by approximately 584,000 MWh. The results provide a theoretical foundation for power angle stability analysis of pumped storage power plants comprising both VSPSUs and ISPSUs, and offer practical guidance for the optimal operation of VSPSUs in renewablerich power systems.