Synergetic Virtual Inertia Control of AC-Excited Variable Speed Pumped Storage and Renewable Energy Sources for Grid Frequency Support

To achieve better grid integration of renewable energy sources and mitigate their impact on the grid, this paper proposes a novel synergetic virtual inertia control (SVIC) scheme for the support of grid frequency with the participation of AC-excited variable speed pumped storage (AC-EVSPS), wind turbine (WT) and photovoltaic (PV). Firstly, the equivalent virtual inertia of the ACEVSPS, WT and PV are estimated considering their current power supply capability and internal dynamics. Subsequently, the way for assigning the load support mission of the three power supply units is proposed based on the defined participation factor that considers each unit's equivalent virtual inertia. In the meantime, a comprehensive frequency regulation framework is developed, which achieves synergies among the three power supply units in power system frequency regulation. Moreover, in order to reduce the risk of secondary frequency drop, the WTs are controlled via an improved VIC scheme which allows its rotor speed to recover to the nominal level in a safer way. At last, simulation case studies and comparisons are conducted to verify the effectiveness of the SVIC method.