Samuelogeno/MPC-Strategy-for-solar-powered-irrigation-pump

Research Project under the supervision of Dr. Simon Meunier at CentraleSupélec | GeePs Lab. The results demonstrate that "hydro-aware" control strategies are essential for the sustainable intensification of solar irrigation, confirming that aquifer properties, rather than solar peak power, are the governing constraint in many African contexts. ## Abstract The decoupling of stochastic renewable energy generation from critical water demand in off-grid solar irrigation systems presents a fundamental control challenge. This is particularly acute in hydrogeologically constrained environments, where aggressive extraction can lead to irreversible aquifer damage [1] This study proposes a Hierarchical Model Predictive Control (HMPC) framework that integrates a high-fidelity hydraulic model based on Thiem’s equilibrium equations. The architecture utilizes a two-layer strategy: a 6-day High-Level Planner for volumetric allocation and an hourly MPC Regulator for real-time constraint enforcement. Utilizing real-world TMY data for Nairobi, the simulation evaluates system resilience. Under constrained aquifer conditions, characterized by low transmissivity (T = 8.7 × 10⁻5 m²/s), a 3000 Wp PV system achieved superior operational results compared to larger systems. While intuition might suggest that more power leads to more water, increasing the PV array size (e.g., to 5000 Wp or more) without a corresponding increase in aquifer yield leads to the Oversizing Paradox. The larger power input from oversized systems dewaters the borehole too quickly, causing the dynamic drawdown to hit critical safety limits and triggering frequent, long pump lockout periods. Furthermore, larger systems are hindered by a higher start-up power threshold (modeled as 20% of rated capacity), meaning they remain inactive during low-irradiance hours that a 3000 Wp system can successfully utilize. Under relaxed hydraulic conditions, the "Oversizing Paradox" is mitigated because the aquifer can replenish the borehole nearly as fast as the pump extracts water. This environment is characterized by high transmissivity (T = 1.0 × 10⁻¹ m²/s), which prevents the rapid dewatering of the borehole that typically triggers safety lockouts in constrained geologies. Consequently, a "more is better" relationship between PV capacity and water yield is establis …