Influencing Factors and Mechanism of AC Fault Transient Overvoltage in Wind Power Grid-Connected System

The new energy collecting system often presents the characteristics of a weak power grid, and the double-fed induction generator (DFIG) easily produces transient overvoltage at the time of fault clearing, presenting low and high voltage ride through, which affects the safe operation of the power system. This paper focuses on the influencing factors of terminal transient overvoltage. Firstly, the influence of external voltage support strength on terminal transient overvoltage is quantized by using two indexes of short circuit ratio and impedance ratio. The results show that a weak power grid with high resistance is more likely to cause terminal transient overvoltage. Based on the tracking accuracy of the PLL, the mechanism of voltage phase jump is studied, and the influence of different fault locations on transient overvoltage is analyzed. The results show that: the closer the fault point is to the main network, the larger the phase angle jump variable, but the smaller the machine terminal voltage amplitude jump variable