Design, system modeling and energy management for a novel hydraulic pumping unit

Abstract

Compared to conventional pumping units with low efficiencies and general hydraulic pumping units using hydraulic accumulators to recover and reuse energy, this article presents a novel multi-source hydraulic pumping unit with the symmetrical structure in order to save energy. First, the balanced mechanical structure through the symmetrical arrangement of double wells can not only decrease the total power of the system significantly but also make the power consumption of the pumping unit drop substantially in the constant speed phase. Uniquely, the proposed pumping unit is jointly driven by a hydrostatic transmission hydraulic system and a small-scale solar–wind hybrid power generation system. The hydrostatic transmission technique enables the system power output to adapt to the load requirements in real time without extra throttling and overflow losses, while the solar–wind hybrid system drives alone in the constant speed phase to save energy and bring environmental benefits. After parameter analyses and calculations, the energy-saving advantage of the proposed system is displayed when compared to a counterpart. Then, the mathematical model of the system is developed, and the rule-based energy management strategy is designed for the energy distribution of the proposed system. The simulation results verify that the feasibility and reasonableness of the proposed system.