Research On Small-Signal Stability Constrained Optimal Power Flow Based On Eigenvalue Sensitivity Of Wind Power System

With large-scale wind power integration,the change of the power system structure and power flow distribution,and the dynamic interaction between the wind turbine generators and synchronous generators(SGs),pose new challenges to the operation stability of the power system.The existing research to the small-signal stability constrained optimal power flow(SC-OPF)mainly adjusts the active power output of the SGs to improve the small-signal stability of the system,however,the effect of the improvement may be limited with the single regulation method.Therefore,it is necessary to further study the influence of wind power integration on the small-signal stability,and study the effect to improve the stability by optimizing the parameters of the wind turbine generators and the reactive power output of the SGs.The main contents and innovations of this paper are as follows:(1)Based on the detailed dynamic model of the doubly-fed induction generator(DFIG),the state matrix of the DFIG-integrated power system is formulated to analyze the eigenvalues introduced by the integration of the DFIGs,and the change of the original eigenvalues of the system.(2)Considering the dynamic interaction between the DFIGs and SGs in the DFIG-integrated power system,the analytical expressions of the sensitivities of the eigenvalues to the active output of the SGs and the PI parameter of pitch angle control of the DFIGs are derived,to linearize the small-signal stability constraint.The SC-OPF model with optimizing above two kinds of parameters is proposed to improve both the critical eigenvalue and weak damping.(3)The analytical expression of the sensitivity of the eigenvalues to the reavtive output of the SGs is derived in the DFIG-integrated power system.The OSC-OPF model based on reactive power optimization is proposed to compare the improvement efforts of active/reactive power optimizations on the weak-damped oscillation modes(4)Based on the Lagrange multipliers,the sensitivity of active power loss to reactive power capacity of the SGs is proposed,considering the stability constraint,to analyze the influence of reactive power capacity adjustment on the power loss and small-signal stability.