Modeling Of Doubly Fed Wind Turbine With Inertia Control And Primary Frequency Modulation Control And Its Influence On Low Frequency Oscillation Of Power System

With the steady increase of the proportion of new energy generation in China,the degree of power electronization of power system is gradually deepening,and the influence of power electronic equipment on the dynamic process of power system is becoming more and more obvious.In order to deal with the dynamic stability of the new power system,the grid operator revised the grid connection guidelines and upgraded the wind farm.The additional control such as inertia control and primary frequency modulation control has been widely used.The doubly fed wind turbine(DFIG)is a typical onshore fan model.In the power system with high wind permeability,the dynamic characteristics of DFIG under different control strategies and control parameters have gradually become more and more important.It is of great theoretical and practical significance to study the influence of DFIG under the control of additional inertia and primary frequency modulation on the dynamic problems of power system.At present,the research on the influence of the system dynamics of DFIG is mainly based on mathematical modeling and simulation,and lacks the physical abstraction of the DFIG and the mechanism analysis of the system dynamic problems.In this paper,the DFIG under the vector control of additional inertia control and primary frequency modulation control is taken as the research object.Based on the idea of amplitude-phase motion equation modeling,a small disturbance model,which can reflect the dynamic characteristics of equipment without relying on the power grid information,is established,and the equivalent inertia damping model is further deduced based on the amplitude-phase motion equation model.Then,in the case of two machine system,the characteristic value analysis is carried out to study the influence of inertia control parameters and primary frequency modulation control parameters on the low frequency oscillation mode of synchronous machine.Then,the interaction analysis is carried out to calculate the interaction coefficients among the key physical quantities,such as the amplitude and phase of inner voltage,the input active power and reactive power of the DFIG,the inner voltage amplitude and phase of the DFIG,the input active power and the terminal voltage of the synchronizer.Then,we obtain the small disturbance model reflecting the interaction between the synchronous machine and the DFIG and the synchronous machine model considering the external network and the interaction with the DFIG.Finally,according to the idea of damping torque method,the synchronous power and damping power of the interaction electromagnetic torque are calculated.The influence law of inertia control and primary frequency modulation control on synchronous power and damping power is qualitatively analyzed.Based on the above physical modeling and interaction analysis results,the physical understanding of the process of the influence of DFIG on the electromechanical oscillation of the synchronous machine is deepened.Meanwhile the paper analyzes and summarizes the influence of the control parameters on the low frequency oscillation of synchronous machine in four machine and two zone system by means of eigenvalue analysis and time domain simulation,and verifies the analysis results of the influence of control parameters on oscillation mode.