Fractional-order load frequency control of a microgrid with electricity-hydrogen unit

This work focuses on the load frequency control (LFC) of integrated energy microgrids that include traditional fossil fuel power units and variable renewable sources such as solar and wind generators. A pumped storage unit and electric-hydrogen-electric (EHE) units are integrated to stabilise frequency fluctuations of the microgrid. A comprehensive mathematical model is developed, and a fractional-order proportional-integral-differential (FOPID) controller is implemented for LFC. A gradient-based optimiser (GBO) is used to adaptively adjust the controller parameters. Case studies and comparisons show that the GBO-FOPID LFC scheme outperforms GBO-PID and whale optimization algorithm-FOPID schemes in frequency deviation metrics. Specifically, in power shortage test scenarios, the proposed GBO-FOPID (EHE) scheme reduces frequency deviation performance indicators, such as the integral of absolute error, the integral of squared error, the integral of time multiplied by absolute error, and the integral of time multiplied by squared error (ITSE), which decreased by 37.88%, 39.68%, 12.58%, and 12.45%, respectively. While in test scenarios involving power surplus and fluctuations in renewable resources, the proposed control method enables the system to have a similar degree of improvement in the above indicators. These improvements highlight the benefits of integrating EHE units in enhancing microgrid frequency control performance.