Analysis of operation characteristics of adjustable-speed pumped storage hydropower unit with AC excitation

The safe and stable operation of the continuing developed power grid can be guaranteed depending largely on the adjustable speed pumped storage hydropower unit (AS-PSH) for its highly efficient peak-frequency modulation ability. In this paper, the design and control strategies of the AS-PSH with AC excitation are proposed. For the evaluation of flexibility and storage capacity, the operation characteristics of the AS-PSH unit are determined through establishing corresponding mathematical models and RTDS simulation tests. The stable operation range and the response speed characteristics of AS-PSH in term of active/reactive power regulation under different working conditions are studied. Results show that the AS-PSH with AC excitation possesses great leading phase capacity and the established de-coupling control system using both AC excitation and governor achieves high response speed. The present study could provide a reliable control basis for the realization of the smooth integration of the intermittent renewable energy sources into the grid.