Enhancing weak minigrid resilience during voltage sags: reactive power support from voltage source inverters

Global efforts to combat climate change are accelerating the adoption of renewable energy sources (RES) and the development of minigrids. These decentralized systems play a vital role in promoting rural electrification and energy independence while supporting global net-zero CO₂ emission goals. By interfacing with the main power grid through inverters, they enhance grid flexibility and sustainability. However, renewable energy-based distributed power generation systems (RE-DPGS) face major stability challenges, especially during voltage sags. These vulnerabilities stem from their low inertia, high impedance, and the inherently intermittent nature of renewable generation. Voltage sags can seriously compromise minigrid stability, causing equipment malfunction, triggering protection devices, or even resulting in system failure. Weak grid conditions intensify these problems, demanding effective countermeasures. This paper investigates the deployment of a three-phase Voltage Source Inverter (VSI) in a weak grid environment as a voltage support mechanism during disturbances. The VSI's capability to inject reactive power rapidly during disturbances makes it highly suitable for mitigating voltage sags. Simulations in a representat ive minigrid setup confirm that reactive power injection significantly improves voltage profiles. This approach enhances RE-DPGS resilience and reliability, ensuring a stable power supply and reinforcing the feasibility of broader renewable energy integration into modern electrical power systems.