Fixed-time control of distributed secondary voltage and frequency for microgrids considering state-constrained

The fixed time control problem for the secondary voltage and frequency of islanded AC microgrids is studied. Based on the multi-agent consensus method, an adaptive fuzzy fixed-time secondary voltage controller considering state constraints and the secondary frequency controller based on control barrier function are proposed. In multi-agent consensus control, each distributed generation is regarded as a nonlinear agent, and the agents communicate with each other through a sparse network. In designing the voltage controller, the adaptive fuzzy estimation of the unknown variables after feedback linearization is used to improve the adaptive ability of the controller and a new sliding mode surface is introduced to make the voltage converge in fixed time. Considering the problem of system state constraints, the barrier Lyapunov function and the control barrier function are used to design the voltage and frequency controllers respectively, so that the system state is within the preset constraint range. The sharing of active power and reactive power is also considered. A proof about fixed time convergence and stability is given. Under the environment of MATLAB/SimPowerSystem, the effectiveness of the proposed controller is verified by the simulation about the load variations and large disturbance of microgrids.