Oloo, Fiona RARampokanyo, MMoholisa, Tsolo ENdlovu, GivenKekana, TiisetsoPhasha, JMabena, KKgasoane, H2025-02-042025-02-042024-08http://hdl.handle.net/10204/13983The global push to reduce carbon emissions has led to the integration of cleaner alternative energy sources into power systems. In South Africa, the 2019 Integrated Resource Plan (IRP) aims for 33% non-inertial variable renewable energy (VRE) capacity, such as wind and solar power, by 2030. While renewable energy offers benefits, its integration poses challenges, particularly on the electrical grid's power system inertia, which is defined as the energy stored in rotating generators. An investigation of the impact of power system inertia erosion on South Africa's power grid is studied and mitigation measures are proposed. By use of Primary Frequency Response (PFR) studies on the transmission network for selected years (2022–2030), the PFR requirements, Rate of Change of Frequency (RoCoF), and critical inertia levels are determined as VRE penetration increases in SA Grid. The study also analyses the effects of Demand Response (DR) and Battery Energy Storage Systems (BESS) on critical inertia. Given that RE sources can be variable and inverter-based, reducing power system inertia provided by conventional machines can lead to increased likelihood of frequency instability during disturbances. Power system inertia plays a crucial role in damping frequency excursions caused by disturbances, with RoCoF being a key indicator of system frequency response. Higher RoCoFs can result in voltage and frequency instabilities, potentially leading to system collapse. Monitoring RoCoF is vital, especially as it depends on factors such as power system inertia. Key assumptions include light loading conditions for scenarios in select years (2022, 2024, 2026, 2028, 2030), a nominal frequency of 50 Hz, and a frequency dead band of ± 0.15 Hz. The study examines various scenarios, including maintaining current reserve requirements and adjusting PFR reserves to meet grid code requirements. Results indicate that the system will remain relatively stiff from 2022 to 2030, although PFR requirements will slightly increase with rising VRE penetration. Critical inertia determination reveals that the South African power system can tolerate low inertia levels (as low as 40 GW.s compared to nominal levels of ~100-110 GWs for light loading on the Eskom system – which is ~ 40 % of nominal inertia levels) with appropriately designed Fast Frequency Response (FFR) services, offering better reliability for system security. Mitigation scenarios show that DR and BESS, if deployed as FFR, can effectively reduce strain on governing reserves for PFR provision. In conclusion, this shows the challenges posed by VRE integration into South Africa's power grid, emphasizing the importance of understanding and mitigating the erosion of power system inertia. The findings suggest that with proper planning and implementation of FFR services, the South African power system can maintain stability and reliability amid increasing VRE penetration.AbstractenPower system inertiaVariable renewable energyVREPrimary Frequency ResponsePFRRate of Change of FrequencyRoCoFConference Presentationn/a