DFIM versus synchronous machine for variable speed pumped storage hydropower plants: A comparative evaluation of technical performance

Nowadays, variable speed (VS) pumped storage technology has become a new trend, for providing better support to power systems towards de-carbonization. This study intends to conduct a comparative evaluation of technical performance of two types of pumped storage hydropower plant (PSHP): the state-of-the-art PSHP based on doubly fed induction machine (DFIM) known as VS and conventional PSHP based on synchronous machine (SM) known as fixed speed (FS). Aiming at this purpose, a case of 343 MW hydro pump-turbine (HPT) coupled to DFIM with 381 MVA in comparison to the SM with same capacity, i.e., 381 MVA, is applied as a study case. The detailed model (discrete mode) in MATLAB/SimPowerSystem (TM) is adopted to conduct simulations under diverse conditions. Simulations and evaluations are for both architectures under two operation modes (generating, motor), in terms of the following items: (1) frequency regulation, (2) transient stability assessment under fault ride-through condition, (3) harmonic distortion, (4) damping of different oscillation modes in power systems, (5) reactive power support considering actual limitations based on P-Q capability curves. The results show the performance differences between the two types of PSHP in diverse aspects for safe, stable and economical operation, as well as the performance in grid ancillary services. (C) 2020 Elsevier Ltd. All rights reserved.