Research on neutral grounding mode in 35kV system of transformer in wind farm station

When the wind farm line fails, the unreasonable neutral grounding mode leads to the simultaneous disconnection of multiple wind turbines, resulting in increasingly serious power loss. Therefore, it is necessary to study the selection of neutral grounding mode. Firstly, taking typical wind farm as the research object, the electromagnetic transient lumped parameter calculation model is established. In addition, the neutral grounding modes are ungrounded, grounded through arc suppression coil and grounded through resistance. Under the condition of different transition resistance, the overvoltage and overcurrent levels of three grounding modes are calculated when single-phase short-circuit grounding fault occurs. Besides, the advantages and disadvantages of different grounding modes are compared and analyzed. Finally, the suggestions for the selection of grounding modes on the 35 kV side of the transformer in the wind farm are given: The 35kV system of transformer in wind farm gathering station is not suitable for neutral ungrounded mode; The compensation function of arc suppression coil greatly reduces the energy of arc reburning, and the arc can extinguish itself; However, due to the large capacitive current of the typical wind farm, the fault overvoltage phenomenon is obvious. It is more suitable to adopt the neutral point grounding through resistance.