Parameter Optimization Of Fast Frequency Response In Wind Turbine With Small-signal Rotor Angle Stability Constraint

To achieve the peak carbon dioxide emissions and to realize carbon neutrality,the proportion of renewable energy like wind power and solar power will increase constantly.However,unlike synchronous generators,renewable energy sources’ active power is decoupled with the power grid frequency because of the used converter,indicating that they cannot naturally provide both inertia support and primary frequency response,and thereby threatening frequency stability.To deal with this issue,deploying the fast frequency response control for renewable energy sources is necessary.The fast frequency response parameter design determines the controller’s characteristics,where there are two difficulties.On the one hand,existing studies show that the fast frequency response may deteriorate the power system small-signal rotor angle stability,and such effect is hard to follow.On the other hand,improper parameter design cannot meet the requirements of the frequency stability,and the relationship between control parameters and frequency dynamics is inexplicit.In view of this,both the small-signal rotor angle stability and frequency stability are supposed to be coordinately considered while designing the fast frequency response parameters.In this paper,the doubly-fed induction generator(DFIG)is taken as the study subject,and a parameter optimization method for fast frequency response is proposed to guarantee both the frequency stability and the small-signal-rotor angle stability.The main research work is as follows:(1)Impacts of DFIG-based fast frequency response on small-signal rotor angle stability are studied.After summarizing existing fast frequency response strategies,based on the DFIG’s dynamics,the model of the power system with fast frequency response for small-signal rotor angle stability is formulated.Impacts of DFIG-based fast frequency response on small-signal rotor angle stability are researched by numerical simulations.Case studies show that improper parameter design may jeopardize the small-signal rotor angle stability,and effects of the fast frequency response on the small-signal rotor angle stability are irregular.(2)The low-order model of DFIG-based fast frequency response for system frequency stability is studied.Based on the fast frequency response strategies summarized in(1),a generic low-order modeling method for fast frequency response strategies is presented,and the application way of the low-order model is illustrated.The error analysis of low-order models is carried out.The low-order modeling and the error analysis are validated by numerical simulation results.With the proposed generic low-order modeling method,the frequency stability can be assessed efficiently,which could satisfy the requirements of optimization.(3)A coordinated parameter optimization of DFIG-based fast frequency response with small-signal rotor angle stability constraints is proposed.Influences of fast frequency response on power frequency dynamic behavior are studied,based on which an error correction strategy for the low-order model is proposed.A parameter optimization model that guarantees both frequency dynamic behavior requirements and small-signal rotor angle stability is proposed,and also a solution algorithm is presented.The effectiveness of the proposed optimization method is validated by simulations.In conclusion,the parameter optimization method for wind turbine-based fast frequency response could coordinately guarantee both small-signal rotor angle stability and frequency stability,which could guide the parameter setting of wind turbine-based fast frequency response.