Virtual Synchronous Generator With Adaptive Sliding Mode Control Strategy Of Microgrid

Compared with the declining fossil energy,distributed energy increasingly brought to the attention of the people for its renewable and environmental friendly.The concept of micro grid with distributed energy is also born at the right moment.Although the micro grid has many advantages,micro grid system is lack of inertia and vulnerable to outside interference compared with the traditional power grid.With the aid of the experience of running characteristics of synchronous generator,voltage source inverters based on virtual synchronous generator(VSG)control are usually used for kinds of distributed generation interfaces in a micro grid to make the system being of stronger inertia.Control strategy under VSG of micro grid is studied in this paper.Firstly,the working principle of the synchronous generator is described in the paper.Body algorithm of the VSG by reference to the model of the synchronous generator is Designed,including the rotor motion equation and the stator voltage equation.At the same time,the VSG power frequency regulator is designed with the help of power frequency regulating principle of synchronous generator.The excitation regulator of VSG is designed by means of the excitation principle of synchronous generator.A 2 order power frequency control system is made an improved optimization by using differential negative feedback of active power and the dynamic response characteristic of the system is improved.Secondly,the condition of a micro grid switching in the power grid is analyzed.According to phase self-synchronizing tracking principle of the voltage between micro grid and power grid,a preliminary synchronization controller of VSG is designed.The static stability of the VSG is analyzed and the influence of some key parameters of VSG algorithm on stability is discussed,which provide a certain reason for the selection of parameters.Then simulation models based on these control strategies are built in the Matlab/Simulink software,and the simulation results verify the moment of inertia and damping parameters effect the output of the system,and also verify the feasibility of preliminary synchronous interconnection and power tracking ability when micro grid connects to power grid.Finally,the underlying voltage control strategy of VSG is studied.Due to unbalanced and nonlinear loads can affect the voltage of inverter,to solve this problem,a voltage adaptive sliding mode control strategy for the VSG is proposed in this study.Using VSG as basic controller,based on the system equations under the ?? two-phase stationary reference frame,in view of the load disturbance and parameter perturbation problem,an adaptive disturbance compensation is designed to reduce the chattering of the output voltage when the system keeps stable.The control strategy proposed,PI double loop decouple control strategy and conventional sliding mode control strategy is made some contrasting simulation experiments.The simulation experiments of the proposed control strategy show its effectiveness and robustness under voltage unbalance and harmonic suppression,improving the power quality of micro grid,and that circulating current among paralleled inverters is effectively reduced.