Enhancing Virtual Inertia Control in Microgrids Cluster, A Novel Frequency Response Model Based on Active Disturbance Rejection Control (ADRC)

The increasing penetration of renewable energy sources has progressively replaced synchronous generation with inverter-based resources, leading to low-inertia power systems in both grid-connected and islanded modes. This paper introduces an enhanced virtual inertia control strategy for microgrid clusters using Active Disturbance Rejection Control (ADRC). Conventional implementations typically rely on droop control combined with PID controllers, which under small-signal analysis fail to capture the complex dynamics of renewable variability and inter-area interactions. Moreover, PID tuning requires significant computational effort and extended simulation times. In contrast, ADRC is a model-free approach that does not depend on precise mathematical representations and demonstrates strong robustness against internal and external disturbances, while reducing computational burden. The proposed ADRC-based control was tested on a two-area microgrid cluster, showing improved frequency stability. Results indicate a frequency nadir of 59.98 Hz and ROCOF of 0.3609 Hz/s, with 6.78% nadir deviation improvement and 37.23% ROCOF reduction compared to PID-based strategies.