Energies (Jul 2019)
Charging–Discharging Control Strategy for a Flywheel Array Energy Storage System Based on the Equal Incremental Principle
Abstract
The widely used flywheel energy storage (FES) system has such advantages as high power density, no environment pollution, a long service life, a wide operating temperature range, and unlimited charging−discharging times. The flywheel array energy storage system (FAESS), which includes the multiple standardized flywheel energy storage unit (FESU), is an effective solution for obtaining large capacity and high-power energy storage. In this paper, the strategy for coordinating and controlling the charging−discharging of the FAESS is studied in depth. Firstly, a deep analysis is conducted on the loss generated during the charging−discharging process of the FESU. The results indicate that the loss is related to the charging−discharging of power. To solve the problems of over-charging, over-discharging, and overcurrent caused by traditional charging−discharging control strategies, this paper proposes a charging−discharging coordination control strategy based on the equal incremental principle (EIP). This strategy aims to minimize the total loss and establish a mathematical model of optimal coordination control with the constraints of total charging−discharging power, rated power limit, over-charging, over-discharging, and overcurrent. Based on the EIP, the optimal distribution scheme of power charging−discharging is determined. Secondly, this paper gives the specific implementation scheme of the optimal coordinated control strategy. Lastly, the charging−discharging coordinated control strategy is verified by examples. The results show that the coordinated control strategy can effectively reduce the loss during the charging−discharging process and can prevent over-charging, over-discharging, and overcurrent of the system. Overall, it has a better control effect than the existing charging−discharging control strategies.
Keywords
