The single-phase fault of wind farm bus system should be quickly removed, and what grounding method should be adopted for bus system?

The main function of grounding transformer is to connect grounding resistance. When the grounding fault occurs in the system, it has high impedance to the positive sequence negative sequence current and low impedance to the zero sequence current, which makes the grounding protection work reliably. Grounding transformer is called grounding transformer for short. According to the filling medium, grounding transformers can be divided into oil-immersed type and dry type. Grounding transformers can be divided into three-phase grounding transformers and single-phase grounding transformers according to the number of phases. Three-phase grounding transformer: the function of grounding transformer is to lead out neutral point for arc suppression coil or resistor when the system is connected in triangle connection or Y connection. This transformer adopts Z-shaped connection (or zigzag connection), which is different from ordinary transformers in that each phase coil is divided into two groups and wound around the magnetic column in the opposite direction. The advantage of this connection is that the zero-sequence magnetic flux of ordinary transformer can flow along the magnetic column, while the zero-sequence magnetic flux of ordinary transformer flows along the leakage magnetic circuit, so Z is connected to the zero-sequence of grounding transformer. According to the regulations, when using ordinary transformer with arc suppression coil, its capacity shall not exceed 20% of the transformer capacity. Z transformer can be equipped with 90% ~ 100% capacity arc suppression coil, and grounding transformer can be equipped with arc suppression coil and secondary load, which can replace the used transformer and save investment cost. Single-phase grounding transformer: Single-phase grounding transformer is mainly used for generator neutral grounding resistance cabinet and transformer with neutral point to reduce the cost and volume of resistance cabinet.