Dynamic analysis of variable-speed pumped storage plants for mitigating effects of excess wind power generation

The integration of hydropower and variable energy sources emerges as a functional method for handling power variability. Due to the advantage of adjustable power input of the pumped storage operation, variable-speed pumped storage plants (VSPSPs) have been proposed as a potential alternative to traditional fixed-speed pumped storage plants (FSPSPs) for dealing with the variable storage demand. The performance evaluation of VSPSPs in coping with changes in loads and variations in renewable energy sources during the energy storage process is crucial to ensure adequate flexibility and reliability of the grid. In this paper, the regulation performance assessment of VSPSP in mitigating wind power variations is presented based on IEEE 14-bus test system. The goal is to draw up the regulation reliability of the VSPSP under pumping mode for balancing the dynamic characteristics of wind power. Specifically, a numerical model of VSPSPs with doubly-fed induction machines is described and developed which is then validated by the measured data in the form of a case study. Moreover, by considering ten wind scenarios having differences in frequency, gradient, guts intensity, and standard deviation; simulations of VSPSP performing power regulation in the pump mode are conducted and the dynamic regulation effects are assessed. Finally, the power regulation quality comparison is provided between the power generation and storage modes to validate the regulation reliability of the VSPSP under the pumped storage operation. The regulation time delay (RTD) ratios of VSUs to FSUs are found in the range of 4.67-9.16%, demonstrating the rapidity of VSPSPs in the power regulation.