Browsing by Author "Melat Bogale Ergete"

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    Frequency Regulation in Ethiopian Power Grid with Solar PV and Hybrid Energy Storage
    (Addis Ababa University, 2025-12) Melat Bogale Ergete; Amare Assefa
    The growing use of renewable energy is a central pathway for reducing greenhouse gas emissions and supporting sustainable power system development. Ethiopia’s power system, which already relies heavily on hydropower and planning in integrating photovoltaic (PV) generation, is moving toward a renewable-dominated grid. While this transition brings clear environmental and economic benefits, it also introduces new technical challenges. In particular, the replacement of conventional synchronous generators with inverter-based renewable resources has reduced system inertia, making the grid more vulnerable to frequency instability during disturbances and interconnection events. This research examines frequency control enhancement strategies for the Ethio–Sudan power interconnection, modeled as a two-area power system. The study focuses on improving inertial, primary, and secondary frequency responses under different PV penetration levels and load disturbance scenarios. To address the challenges associated with reduced inertia, a hybrid energy storage system (HESS), combining a supercapacitor and a battery energy storage system, is proposed and installed in the low-inertia area of the interconnected network. The supercapacitor and battery is designed to respond rapidly to disturbances, providing fast inertial and primary frequency support respectively. This significantly limits the rate of change of frequency (RoCoF) and reduces the depth of the frequency nadir or the peak frequency immediately after a disturbance. The battery energy storage system operates in coordination with the filtered area control error(ACE) method to support secondary frequency control, enabling smooth frequency recovery and reducing steady-state frequency deviations. In addition, a contingency-based sizing approach for the HESS is developed to ensure that operational limits and system frequency performance requirements are satisfied. The effectiveness of the proposed strategy is demonstrated through detailed MATLAB/Simulink simulations of the Ethio–Sudan interconnected system under sudden load changes and varying levels of PV penetration. Simulation results clearly show that the inclusion of the hybrid energy storage system(HESS) leads to substantial improvements in RoCoF reduction, frequency nadir and peak enhancement, oscillation damping, and settling time when compared to cases without energy storage. Overall, this study demonstrates that coordinated hybrid energy storage control can effectively compensate for inertia loss in renewable-rich interconnected power systems