EFFICIENCY OF USING RENEWABLE ENERGY SOURCES FOR POWER SUPPLY OF WATER LIFTING PUMPING SYSTEMS

• Date: 2026
• Main Author: Popovych , O.
• Format: Article
• Language: Ukrainian
• Published: Institute of Renewable Energy National Academy of Sciences of Ukraine 2026
• Subjects: induction motor; pumping unit; photovoltaic modules; frequency control; gravity energy storage; comprehensive math-ematical model.
• Online Access: https://ve.org.ua/index.php/journal/article/view/611
• Journal Title: Vidnovluvana energetika

The efficiency of structures of electromechanical water supply systems powered by renewable energy sources is investigated under conditions where static head losses constitute a significant share of the total hydraulic network head losses. In such cases, at nominal supply parameters of the pumping unit, the energy potential of the renewable energy source is not utilized when its instantaneous power is lower than the required power consumption of the pumping unit, and is only partially utilized when it exceeds this value. Using a water lifting system powered by photovoltaic modules as an example, the paper presents the results of a comparative numerical study based on comprehensive mathematical models of the system. Conditions for the feasibility of applying water lifting systems with variable supply frequency and intermediate energy storage devices instead of systems with nominal supply parameters of the pumping unit are determined. The study, taking into account the daily non-uniformity of solar radiation, is performed using approximation dependencies of this non-uniformity for June and January conditions. A simulation model of the water lifting system is substantiated, incorporating approximation of pump head characteristics as functions of angular velocity and flow rate, as well as refined modeling of an induction motor under low-load conditions. Steady-state operat-ing parameters of the electromechanical water lifting system are determined by solving differential equations of electrical, mechanical, and hydraulic equilibrium until steady-state conditions are reached. The optimal area of photovoltaic modules (solar panels) is determined according to the criterion of maximizing the daily volume of extracted water per unit area of the panels. Based on modeling results of steady-state modes with variable supply frequency, a dependence of the pumping unit productivity as a function of renewable energy source power is obtained. This dependence is used for a comparative study of three system configurations: with nominal supply parameters; with variable frequency and voltage; and with the use of an intermediate energy storage device—a gravity energy storage unit. It is shown that the feasibility of applying frequency and voltage control of pumping units in water lifting systems powered by renewable energy sources instead of stable industrial grid conditions increases with decreasing solar radiation intensity. In this case, the increase in the daily extracted water volume exceeds 80%. Under limitations of frequency control capabilities caused by dominance of static head over pump head at low solar radiation levels, the application of an intermediate energy storage device – a gravity energy storage unit – is justified.