Lightning protection wiring method for distribution transformer based on inductance filter

Abstract

The invention discloses a lightning protection wiring method for a distribution transformer based on an inductance filter, and relates to the technical field of lightning protection. The lightning protection wiring method for the distribution transformer based on the inductance filter comprises a high voltage side lightning arrester of a distribution transformer, a low voltage side lightning arrester of the distribution transformer and an inductance filter. One end of the inductance filter is connected to a neutral point of the low voltage side of the distribution transformer, and the other end of the inductance filter is connected to a metal casing of the distribution transformer. The impedance of the inductance filter increases as the frequency of the current flowing through the inductance filter increases, and the impedance of the inductance filter in a high impedance state when lightning current acts, so that lightning current flowing into the neutral point of the low voltage sideof the distribution transformer due to counterstrike can be effectively isolated when the lightning current flows into the ground through a distribution transformer grounding grid in a case that lightning strikes the distribution transformer. At the same time, the impedance is small when the power frequency current acts, so as to ensure a working grounding and a protection grounding of the neutralpoint of the distribution transformer are normal.

Description

technical field [0001] The invention belongs to the technical field of lightning protection, and in particular relates to a wiring method for lightning protection protection of distribution transformers based on an inductance filter. Background technique [0002] The 10kV distribution transformer directly supplies power to users in the power system, and once damaged, it will directly lead to interruption of power supply for users. Distribution network lines are widely distributed and there are many equipments. Most of the distribution lines are mainly overhead lines. There is no lightning protection line, and the probability of being struck by lightning is relatively high, especially for distribution transformers. If lightning protection measures are insufficient or unreasonable, lightning overvoltage It will intrude into the distribution transformer along the line, generate positive and negative transformation overvoltage, cause the main insulation of the transformer or int...

AI Technical Summary

Problems solved by technology

The wave impedance of the low-voltage coil is much larger than that of the low-voltage line, which will cause the voltage drop to basically concentrate on the low-voltage coil. At this time, even if the arrester on the low-voltage side of the transformer operates, there will be residual voltage of the arrester on the low-voltage coil, which will be transmitted to the high-voltage side coil through electromagnetic induction. Overvoltage occurs between the neutral point of the high-voltage side and the shell, which may cause damage to the transformer

According to the simulation calculation, when the intrusion lightning current amplitude on the high-voltage side of the distribution transformer reaches 20kA, even if the arrester on the low-voltage side operates reliably, an overvoltage of 98kV will still be generated at the neutral point of the high-voltage side, exceeding its insulation tolerance range

At the same time, the overvoltage on the low-voltage side of the transformer will be transmitted to the users on the low-voltage side, which will bring danger to users

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