Overvoltage protection device for neutral point of transformer

Abstract

The invention discloses an overvoltage protection device for a neutral point of a transformer. The overvoltage protection device comprises a lightening arrester, a discharging gap, an isolation transformer, a measuring unit, a control unit and a high voltage impulse generator unit, wherein the measuring unit measures the amplitude value and time duration of power frequency voltage of the lightening arrester, when the amplitude value of the power frequency voltage exceeds a preset voltage value and the time duration also exceeds a preset value, the control unit sends a trigger signal to trigger the high voltage impulse generator unit to generate high voltage impulse; after being boosted by the isolation transformer, the high voltage impulse induces a trigger electrode to generate spark and discharge, and further induces the discharging gap to discharge, thereby restricting the size and duration time of the power frequency voltage of the lightening arrester, accurately matching the protection characteristics of the discharging gap and the lightening arrester, avoiding the explosion caused when the lightening arrester is subject to long-time power frequency follow current. Therefore, the overvoltage protection device for a neutral point of a transformer provided by the embodiment of the invention can operate safely and operating parameters of the device can be controlled and adjusted very easily.

Description

technical field [0001] The invention relates to the technical field of transformer protection, in particular to a transformer neutral point overvoltage protection device. Background technique [0002] Power transformer neutral point overvoltage protection has been a difficult problem in power grid operation for many years. The generation of neutral point overvoltage of power transformers will endanger transformer insulation. For example: when lightning waves invade the substation from the line and reach the transformer neutral point, It will generate high lightning overvoltage at the neutral point of the transformer, which poses a threat to the neutral point insulation of the transformer, and even damages the neutral point insulation of the transformer; When the excitation inductance resonates with the line-to-ground capacitance, a power frequency transient overvoltage is generated at the neutral point of the transformer, which poses a threat to the neutral point insulation ...

AI Technical Summary

Problems solved by technology

[0003] Currently commonly used transformer neutral point overvoltage protection devices use lightning arresters or discharge gaps. However, discharge gaps have the problems of high randomness of discharge voltage and difficult control and adjustment of operating parameters. explosion occurs

Images