Multi-stage ESO-ADRC for frequency stabilization in off-grid systems with high renewable energy and EV penetration.

Urban hybrid off-grid power systems (UHOGPS) face critical frequency stabilization challenges as renewable energy sources (RES) and electric vehicles (EVs) dominate modern grids, introducing complex nonlinearities, stochastic disturbances, and dynamic uncertainties. To address these limitations, this paper proposes a multi-stage extended state observer with generalized active disturbance rejection control (MSESO-GADRC), a novel framework that hierarchically decomposes disturbances into targeted frequency bands for precise mitigation. The key contribution lies in its multi-stage ESO architecture, which uniquely integrates two-, three-, and four-stage observer configurations with adaptive bandwidth tuning to isolate and suppress low-, medium-, and high-frequency disturbances while compensating for unmodeled dynamics. Simulations under renewable intermittency, EV charging transients, and load disturbances demonstrate the framework's superiority: it achieves 43.40-85.71% smaller frequency deviations and 38.46-64.34% faster settling times compared to 1PD-DOP-3PID, SESO, FO-IMC, and SBL-PI controllers. These advancements validate the MSESO-GADRC's robustness in UHOGPS with 70% RES/EV penetration, offering a critical pathway to stabilize decarbonized grids. By explicitly resolving the trade-off between disturbance rejection and system nonlinearity compensation, this work provides a foundational control paradigm for future high-renewable microgrids.