At present,many countries advocate energy conservation and emission reduction.The massive consumption of traditional fossil energy leads to excessive carbon dioxide emissions,which is not conducive to the national vision of carbon peak carbon neutrality.Therefore,renewable energy distributed generation technologies have broad development prospects.The micro gas turbine has the advantages of rapid response,stable output,reliable fuel economy,and environmental protection,which plays an important role in the distributed power generation system.The research on the micro gas turbine control system can not only improve the work efficiency but also help to achieve energy conservation and emissions reduction.The micro gas turbine system is a time-varying,nonlinear,and multivariable coupling system.Multi-source disturbances are adversely affecting the system,including internal disturbances such as model parameters perturbation,and external disturbances such as load torque and power grid voltage changes.The sliding mode control is a control algorithm with a simple design and strong robustness,which has been widely used in industrial control systems.In this paper,the sliding mode control of the micro gas turbine system is studied.Considering the complicated structure of the whole control system,this paper designs sliding mode controllers based on the micro gas turbine generation system and grid-connected inverter system respectively.The structure and electromechanical characteristics of the micro gas turbine system are first introduced in this paper,and the mathematical models of the power generation system and the grid-connected inverter system are established respectively.Based on the micro gas turbine generation system model,a sliding mode control algorithm based on the linear sliding mode surface is proposed,and chattering problem and convergence performance are analyzed.Then,considering that the system is affected by load fluctuation,a finite time disturbance observerbased continuous terminal sliding mode controller is proposed for the system with mismatched disturbances.Simulation results show that the proposed method has a better dynamic performance and a stronger disturbance rejection ability.Based on the grid-connected inverter model,a decoupling control algorithm for output current is presented.This algorithm can solve the current coupling problem between the d and q axes caused by coordinate transformation,but it is difficult to get good control performances when under the influence of disturbances.Therefore,a sliding mode controller based on an integral sliding mode surface is designed in this paper.Simulation and experiments show that the proposed algorithm can improve the dynamic and steady-state performance as well as the quality of grid-connected current.To further study the power harmonic problem in the grid-connected inverter,a fast Fourier transform is used to analyze.Considering the effects of multi-source disturbances,a composite disturbance observer is designed for disturbance estimation and compensation.Finally,a composite disturbance observer-based composite sliding mode control algorithm is proposed.Simulation and experiments show that the designed composite disturbance observer can accurately estimate various kinds of disturbances,and the effectiveness of the proposed control method is verified. |