Modeling and Experimental Investigation of the Optimal Operating Parameters of a Bucket-Bladed Micro Hydropower Plant under Variable WaterConditions

Abstract

Relevance: the efficient utilization of renewable energy sources, particularly small-scale hydropower potential, is becoming increasingly important amid growing energy demand. Micro-hydropower plants operating under low and medium hydraulic heads provide an opportunity to generate electricity from local water resources. However, under conditions of variable water discharge and hydraulic head, determining the optimal operating regime of the hydraulic turbine and improving its energy efficiency remain important scientific and practical challenges. Therefore, determining the optimal operating performance of a bucket-bladed micro-hydropower plant depending on water discharge, hydraulic head, rotational speed, and blade geometric parameters is highly relevant.

Aim: the aim of this study is to determine the optimal operating parameters of a bucket-bladed micro-hydropower plant turbine operating under variable water discharge and hydraulic head conditions through mathematical modeling and experimental investigations. In addition, the study evaluates the relationships among turbine rotational speed, torque, mechanical and electrical power, and efficiency.

Methods: a mathematical model and computational algorithm were developed for the bucket-bladed hydraulic turbine. Water discharge, hydraulic head, flow velocity, number of blades, blade installation angle, rotational speed, torque, mechanical power, and hydraulic efficiency were calculated. Multi-stage iterative calculations and the penalty function method were used to determine the optimal operating regimes. In addition, laboratory and practical experiments were conducted to evaluate the energy efficiency of the micro-hydropower plant, during which water discharge, hydraulic head, rotational speed, torque, and mechanical and electrical power were measured. Based on the experimental results, a regression model was developed in the MATLAB environment.

Results: the calculation and experimental results showed that the energy performance of the micro-hydropower plant is significantly dependent on water discharge, hydraulic head, and turbine rotational speed. Under the calculated operating conditions of H = 30 m and a total flow rate of Q = 0.018 m³/s, the optimal rotational speed of each hydraulic turbine was 540 rpm, with a mechanical power output of 2150 W, while the total mechanical power of the two turbines reached 4300 W. The experiments were conducted within the ranges of H = 5–30 m, Q = 0.0036–0.009 m³/s, and N = 220–540 rpm. The electrical power increased from 300 W at a hydraulic head of 5 m to 4385 W at 30 m. The agreement between the mathematical model and experimental results was R² ≈ 0.929, indicating the high accuracy of the developed model.