Fault Tolerable Cooperative Control for Charging Supercapacitors of Catenary-Free Trams

Supercapacitor-powered devices are now being used as main supply units in catenary-free trams, for their rapid charging and environmental-friendly performance. Faced with the high-power-charging load from trams, the cooperative control protocol is widely adopted to charge onboard supercapacitors due to the properties of reducing current overshoot and imbalance. However, the charging system under the protocol inevitably suffers from potential fault data from physical malfunctions or cyberattacks. To deal with it, in this article, a reliable cooperative control strategy (RCCS) is designed to alleviate the effects of fault data regardless of where it comes from and protect the system's performance. Specifically, first, we introduce the cooperative charging system model and analyze the causes and effects of fault data. Then, we provide a total current control protocol (TCCP) and a data cooperative-screening control protocol (CSCP) to deal with fault data from the physical layer and cyberlayer, respectively. Combining TCCP and CSCP, RCCS is designed and the system stability is proved based on Lyapunov stability analysis under RCCS. Finally, both simulations and experiments are conducted to demonstrate the effectiveness of the proposed algorithms.