Rotor short‑circuited start‑up strategy for a doubly fed induction machine‑fed large‑rated variable‑speed pumped storage unit operating in pumping mode

다국어 초록 (Multilingual Abstract)

The starting time of a large-rated variable-speed pumped storage unit (PSU) operating in pumping mode is crucial in the power balancing scenario in a modern power system because it establishes the transition period from generation to pumping modes, and vice versa, which determines the power system stability. Doubly fed induction machines (DFIM) are preferred in large-rated variable-speed PSUs (> 100 MW) because they ensure variable-speed operation through partial-rated power converters. Initiating the DFIM in pumping mode is challenging, but it is overcome by utilizing rotor-side power converters. The start-up of DFIM is preferred through short-circuiting the stator windings and supplying power to the rotor windings via power converters. However, this task can be performed through either short-circuiting the rotor or stator windings. This work detailed the field-oriented vector control strategies of the rotor short-circuited method and compared the results with the conventional stator short-circuited method in a commercial 306 MVA DFIM-fed variable-speed PSU. Results demonstrate that short-circuiting the rotor windings reduces the starting time and power consumption by 27.5% and 27%, respectively, compared with the typical starting method. This reduced starting time is preferred by the grid authorities because it improves the power system stability. Furthermore, experimental results are validated in the laboratory with a scaled-down unit of 7.5 kW DFIM.