Frequency Optimal Control Strategy Based On Cooperative Adaptive Virtual Synchronous Generator

In the process of grid connection,the traditional inverter control of distributed generation is lack of inertia and damping.When the system is disturbed,it can not return to steady state through self-regulation,which brings great challenges to the stability of the system.The virtual synchronous machine technology makes the grid connected inverter have the voltage and frequency regulation characteristics of synchronous generator by adjusting the control parameters,and makes the grid connected inverter have the inertia and damping required by the system to restore stable operation,which is of great help to ensure the safe and stable operation of the power system.The traditional virtual synchronous generator improves the frequency response characteristics of the system,enhances the anti disturbance ability of the power grid,but its dynamic regulation performance decreases.On this basis,this paper studies the cooperative adaptive control strategy of inertia and damping coefficient of virtual synchronous generator to solve the above problems.To solve the above problems,the main contents of this paper are as follows:Firstly,the influence of different kinds of distributed generation on the stability of power and frequency is analyzed.On this basis,the control technology of virtual synchronous machine is introduced to solve this problem.The topology of virtual synchronous generator is analyzed.The model of virtual synchronous generator is established by introducing the electrical equation and rotor motion equation into the control strategy of inverter.Secondly,aiming at the problems of coordinate transformation and decoupling in the virtual synchronous machine model built in the rotating coordinate system,this paper improves it by transforming it into a virtual synchronous machine model built in the two-phase static coordinate system.On the basis of the model,the two main inertia parameters,the moment of inertia and the damping coefficient,are analyzed.The interaction among the parameters such as inertia time constant,moment of inertia and damping coefficient,as well as the setting mode of these parameters are obtained.Finally,the adjustment principle of the existing adaptive control strategy and its shortcomings in the process of power frequency adjustment are analyzed.The problem is solved by using the cooperative adaptive control strategy which considers both the moment of inertia and the damping coefficient.The influence of the numerical changes of the moment of inertia and damping coefficient on the stability of power frequency regulation is analyzed.It is concluded that the strategy proposed in this paper can reduce the overshoot and regulation time of the system frequency at the same time.Matlab /Simulink simulation is used to verify the control effect of the proposed control strategy,proving the effectiveness of the strategy.