Device and method for preventing 220kV main transformer gap protection malfunction

Abstract

The invention discloses a device and method for preventing 220kV main transformer gap protection malfunction and solves a problem of cut off of high voltage side power supply of a main transformer because of main transformer gap protection malfunction when main transformer gap protection motion time delay is smaller than the reclosing time set during single-phase grounding short circuit of a lineof a 220kV transformer station. If a gap of a neutral point of the main transformer for gap grounding is broken down by discharging, a neutral point zero sequence current value (3 I0) is greater thana gap overcurrent protection motion value (I0P), and the automatic reclosing signal of the line of the 220kV transformer station during generation of single-phase grounding is received by a gap protection device (5), if automatic reclosing succeeds, gap protection takes no motion; if automatic reclosing fails, gap protection takes no motion. The method is advantaged in that safe and stable operation of the power grid is guaranteed, and power supply reliability is improved.

Description

technical field [0001] The invention relates to a main transformer protection device of a substation, in particular to a device and method capable of preventing 220kV main transformer gap protection from malfunctioning. Background technique [0002] In a 220kV substation, two main transformers are usually configured. According to regulations, the neutral point of one of the main transformers is directly grounded, and the neutral point of the other main transformer is grounded through a gap. Since the 220kV system is a large-current grounding system, the neutral point of a main transformer needs to be directly grounded to prevent the excessive zero-sequence voltage generated at the neutral point of the transformer from damaging the system insulation during a fault; The zero-sequence reactance is not too small, so the neutral point of the other main transformer is not grounded directly, but is grounded with a gap. The way of gap grounding is that the neutral point of the main...

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Problems solved by technology

[0004] The invention provides a device and method for preventing 220kV main transformer gap protection from malfunctioning, which solves the problem that the main transformer gap protection action delay is less than the reclosing time set when a single-phase ground short circuit occurs in the line of the 220kV substation, causing the main The faulty action of variable gap protection cut off the power supply on the high-voltage side of the main transformer, which caused the technical problem of the shutdown of the main transformer

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