Abstract: A variable-speed pumped storage unit with a full-size converter features a wide regulation range and excellent control performance. It is a cutting-edge technology developed in the global pumped storage industry, but its refined numerical models need to be developed urgently, and dynamic characteristics of pump power regulation and optimization of regulation comments need to be studied urgently. In this paper, MATLAB/Simulink is used to build a numerical model for simulating the transient process in the hydraulic-mechanical-electric coupled system of a variable-speed pumped storage power station with a full-size converter and for establishing a control strategy for the unit’s power regulation based on power feedback. Through numerical simulations, energy conversion characteristics of this variable-speed unit are revealed, and its dynamic characteristics under power regulation in pump mode is studied. The results demonstrate that when the unit’s input power decreases, its power regulation speed and the overshoot of its main parameters are positively correlated with the change rate of its power command, but the correlation becomes weaker after a certain change rate threshold. This work is useful for further study and future operation of this new type of variable-speed units in China.

Key words: variable-speed pumped storage, full-size converter, numerical model, power regulation in pump mode, dynamic characteristics