Fixed-Time Secondary Controller for Rapid State-of-Charge Balancing and Flexible Bus Voltage Regulation in DC Microgrids
Yuji Zeng, Qinjin Zhang, Yancheng Liu, Haohao Guo, Siyuan Liu, Fengkui Zhang, Shi You, Yuanting Hu, Heyang Yu
Abstract
Typically, the secondary controllers for distributed battery storage units (BSUs) have been designed using asymptotic or finite-time consensus protocols, which may not be suitable for DC microgrids with intermittent renewable energy operations and frequent load power fluctuations. This paper presents a novel fixed-time secondary controller, which designed to achieve both rapid State-of-Charge (SoC) balancing and flexible bus voltage regulation for parallel BSUs in DC microgrids. The proposed fixed-time secondary controller provides a bounded settling time independent of initial conditions, whereas also offering a rapid SoC balancing speed. Pinning control is combined with the proposed fixed-time secondary controller to achieve flexible regulation and accurate restoration of the average bus voltage. This scheme saves computing resources and releases communication pressures. Rigorous Lyapunov stability proofs, along with experimental results using StarSim, demonstrate the effectiveness and superiority of the proposed fixed-time secondary controller under various testing scenarios.