Abstract：This paper analyzes an accident of voltage loss of a section of 10kV bus in 110kV A substation due to misoperation of grounding transformer protection. It is found that the current transformer (CT) configuration of grounding transformer zero sequence is unreasonable in the process of 10kV system neutral point reconstruction, and a solution is proposed to install the zero-sequence protection CT on the high side of the grounding transformer at the small resistance of grounding transformer neutral point. This method can ensure that the grounding transformer protection will not act wrongly when the arc suppression coil is compensated and before the small resistance is input, which improves the power supply reliability of the power grid. This is of practical significance to the reconstruction project of 10kV system neutral point grounded by small resistance in parallel with arc suppression coil.
2021, Vol. 22 
