The Analysis of the Voltage Drivers' Effects on Creating Stability in Variable-Speed Pumped-Storage Power Plant

Abstract

Enhancing the stability and efficiency of variable speed pumped storage power plants through advanced multilevel converter drivers ensuring high-quality energy production and stable steady-state operation in large-scale power plants such as variable speed pumped storage power plants (VSPSPs) is a critical challenge for power grids. The role of advanced drivers utilizing multi-level voltage source converter (MLVSC) technology in enhancing the stability and efficiency of VSPSPs throughout power grid duty cycles is undeniable. This study investigates the impact of innovative driver designs on improving steady-state operation in VSPSPs. A novel driver featuring a flexible DC link and an advanced control topology is introduced, incorporating two-level and three-level voltage source converters (2LVSC/3LVSC) with an innovative 8 + 1 power module arrangement. To validate the proposed approach, a 250 MW VSPSP is compared to a 2.2 kW variable speed wind power plant (VSWP), assessing steady-state performance and thermal stability. Simulation results and statistical analyses conducted by use of MATLAB and PLEXIM software confirm that the implementation of 3LVSC-ANPC (8 + 1) drivers with direct torque and flux control (DTFC) significantly enhances the steady-state performance of the VSPSP. Additionally, this approach improves mean time between failures (MTBF), system reliability, repair speed, and maintenance efficiency, while reducing losses and increasing overall energy efficiency. These findings highlight the effectiveness of the proposed driver technology in optimizing VSPSP performance and ensuring long-term operational stability.