The impact of large-scale wind power integration on the stable operation of power system has attracted great attention. This paper presents a method to analyze the influence of doubly-fed induction generation (DFIG) on the power system transient stability by using transient energy function. The transient energy function of the system with DFIG is constructed based on the rotor equation of the system by introducing the equivalent parallel grounded admittance model of DFIG and the critical energy of the system is given. Furtherly, the effect of DFIG on the system transient stability margin is analyzed. In addition, combined the influence of DFIG on the change of system state variables with the energy accumulation process during the fault, the influence mechanism and quantitative analysis of the DFIG on the system critical clearing time and transient power angle variation of synchronous machines are realized. In the simulation analysis, two different LVRT schemes of DFIG are compared, and the simulation results verify the correctness of the proposed method.
Keywords transient stability, doubly-fed induction generation (DFIG), transient energy function (TEF), stability margin, critical clearing time (CCT), LVRT