Adaptive analysis of main transformer protection in hybrid wind farms

Abstract

With the development of wind power technology, wind farms have gradually formed a mixed operation pattern dominated by DFIG and PMSG. By analyzing the short-circuit current characteristics when a fault occurred in the main transformer protection zone of the wind farm and the hybrid wind farm is connected to the grid, the possible impacts of the short-circuit current of the hybrid wind farm on the protection of the transformer is studied. The results show that after mixing different unit types, when the fault occurs in the main transformer protection zone of the wind farm, the short-circuit current contains the second harmonic component, and its attenuation speed is related to the number of PMSG, the number of DFIG, the fault location, and the severity of the fault. Under the influence of above factors, the blocking time of the second harmonic blocking protection will be prolonged, thereby increasing the operating time of the ratio differential protection.