Hybrid AC/DC grids are a critical evolution pathway for modern power systems. Conventional parallel interlinking converters incur significant costs and losses due to high system-level voltage stress, while series-type converters like interline DC power flow controllers offer inherently limited control flexibility. To address these combined challenges, this paper proposes an energy storage-based power lever (ES-PL) with its control strategy. This device, connected in series within the interlinking lines, leverages small-scale power of energy storage to enable large-scale, flexible power flow regulation across the entire grid. Based on the circuit topology and operational principles of the proposed ES-PL, a global flexible power regulation strategy is designed for hybrid AC/DC grids. This strategy achieves power sharing within DC subgrids and enables quantitative power control for AC subgrid. A small signal model analyzes the impact of wide-range disturbances in key control parameters on system stability, verifying the stability of the proposed control strategy under dynamic conditions. Finally, a proof-of-concept prototype of the ES-PL is constructed to verify the effectiveness of the proposed device and its control strategy.