Mechanism Analysis of Transient Overvoltage after Large Disturbance Considering Dynamic Characteristic of Wind Turbine Generators

Under the background of centralized access of large-capacity high-voltage direct current (HVDC) transmission and high-ratio renewable energy (RE) generation, this paper studied the mechanism and impact factors of transient overvoltage under large disturbance considering dynamic characteristic of wind turbine generators (WTG). Firstly, the theoretical equations calculating the magnitude of transient overvoltage on the converter station (CS) side and the WTG side after AC/DC disturbance were derived. Then, the mechanism of transient overvoltage caused by AC/DC disturbance were analyzed. Finally, the impact of different factors such as WTG active/reactive power characteristics during low-voltage ride through (LVRT) on transient overvoltage was analyzed combined with simulation. All the conclusions were verified through simulation of practical case systems. The study results reflected that the LVRT characteristic makes the WTGs be another ‘reactive power source’ resulting in transient overvoltage besides the CS, the higher of the transient overvoltage is caused by the smaller of the WTG active output and the larger of the WTG reactive output.