Sequence Impedance Modeling and Analysis of Double-fed Induction Generator Based on Virtual Synchronous Control

The stability problem caused by the interaction between traditional doubly fed induction generator (DFIG) and the power grid under the condition of weak power grid is prominent. DFIG based on virtual synchronous control can provide support for power grid frequency and significantly improve grid-connected stability. This paper presents a method of sequence impedance modeling for DFIG based virtual synchronous control. Firstly, the impedance model of DFIG based virtual synchronous control with power outer ring is derived by using the method of harmonic linearization. Secondly, the output impedance characteristics of DFIG based virtual synchronous control are obtained and compared and verified by frequency scanning method based on the model. Finally, the effects of different parameters on the output impedance characteristics are analyzed.