Research On The VSG’s Modeling And Control Strategy Based On Hamilton Approach

Renewable energy characterized by cleanness,circulation and regeneration will have a bright future.Therefore,the renewable energy are gradually introduced to the traditional transmission and distribution power grid.However,when interfacing to the grid,power and electronic devices are most commonly required.These devices have fast response speed but fail to provide inertia and damping to the power grid,which will have a great impact to the system stability and make it vulnerable.To solve this problem,the key lies in improving inertia and damping of the system.Virtual Synchronous Generator(VSG)technology aims to mimic the port characteristics of the traditional synchronous generator to control the electronic devices.Two main merits will be achieved including the output of the new energy system presents the characteristics of synchronous generators while the virtual inertia and damping will be provided to the power system.In this paper,an enhanced VSG technology with Hamilton’s theory will be firstly introduced and method of the adaptive control strategy and multi-machine control strategy will be illustrated.The main research results are as follows:(1)The principle of synchronous generator is analyzed in detail,and the fourth-order VSG mathematical model is established by combing the excitation and valve modeling with Hamilton approach.The following lays the foundation for the study of adaptive control strategy and multi-machine strategy.(2)In order to make full play to the advantages of adjustable VSG parameters and the flexibility of the control system of the inverters,an adaptive VSG control strategy is designed.In this algorithm,the inertia time constant and damping coefficient can be adaptively selected according to the actual application situation.Meanwhile,the range of the two key parameters of the system can be obtained according to the small signal model analysis of the system.(3)A control strategy for multi-VSG parallel system is proposed.In the system,the circulation caused by system parameter perturbation and the accurate power allocation are necessary to be considered.To solve the above problems,a voltage and current control loop with inductive output impedance is designed.On the basis of single-machine VSG model,the dissipative Hamilton model of multi-synchronous generator is introduced to realize the control loop.(4)In order to verify the effectiveness of the proposed VSG control strategy,simulation model is established in Matlab/Simulink.The adaptive control algorithm has a certain effect on the system oscillation,and shows a good effect on the transient output response and the reduction of the stability time.The parallel control of multi-VSG system is used to suppress circulation and realize power.The effect of accurate allocation is obvious,and the robustness and stability of the system are improved to a certain extent.