Coordinated Control of Supercapacitors and Hybrid Electric Vehicles for Frequency Regulation in Renewable Power Grids Considering Communication Delays

Abstract

Integrating renewable energy sources into modern power grids enhances sustainability but reduces the inherent inertia provided by synchronous generators, leading to larger frequency fluctuations and degraded dynamic stability. To address this issue, this paper proposes an advanced inertia-damping emulation (IDE) strategy based on a coordinated hybrid energy storage system (HESS) comprising supercapacitors (SCs) and fuel cell-battery-based hybrid electric vehicles (FC-BHEVs) for frequency regulation in low-inertia power grids. SCs provide fast virtual inertia support owing to their high-power density, whereas the FC-BHEVs provide virtual damping support through sustained power compensation. A supplementary integral controller is further incorporated to restore the system frequency to its nominal value and overcome the limitations of primary frequency control. The proposed framework also considers communication time delays and practical power and energy constraints in the frequency-control process. The proposed strategy is evaluated in an islanded microgrid under renewable penetration, load disturbances, and parameter uncertainties, and is further validated in an interconnected two-area multi-source power system under generation outages, random load variations, renewable power fluctuations, and communication delays. MATLAB simulation results demonstrate that the proposed HESS-based strategy achieves superior frequency regulation, reduced frequency deviations, improved damping, faster recovery, and enhanced inter-area power exchange stability compared with conventional inertia emulation and IDE methods, demonstrating its effectiveness and robustness for enhancing the frequency stability of future renewable-dominated power grids.