Model-free adaptive optimal control for fast and safe start-up of pumped storage hydropower units

Pumped storage unit (PSU) is a special kind of hydropower unit, that undertakes the task of power generation, and performs the function of energy storage. Due to its unique advantages, pumped storage power stations have been extensively developed in China in recent years and play an important role that is difficult to be performed by other energy sources. Although many studies have been carried out on the control of PSUs, most of the control algorithms are based on object models, which results in the control performance depending on the model accuracy to a large extent, limiting the practical application of these algorithms. For this reason, a preliminary application of model-free adaptive control in PSUs is investigated in this paper. Firstly, a refined nonlinear model of PSU is established, secondly, the model-free adaptive controller of PSU and its parameter optimization strategy are designed, and finally, verification is carried out by simulation studies for four different start-up conditions, and a comprehensive comparison is made with control strategies such as proportional-integral-derivative (PID), fractional-order PID, and nonlinear generalized predictive control. The results show that the proposed method has significant improvement in both speed and head control performance compared with other methods, with the regulation time being on average at least 5.53 s faster and the overshoot being on average at least 2.85 % lower. It proves the effectiveness and superiority of the method. In addition, the proposed method reduces energy consumption in the regulation process, and the computational cost meets the real-time control requirements, which has a wide range of application prospects.