Inrush current suppression method applied to industrial frequency transformer in controllable inversion

Abstract

The invention discloses an inrush current suppression method applied to an industrial frequency transformer in controllable inversion. The method comprises the following steps of: arranging a single chip microcomputer on the power supply side of an industrial frequency transformer to control an H-bridge circuit, so that an industrial frequency voltage can be output; carrying out soft starting; when the primary side voltage of the industrial frequency transformer is a specific zero crossing point, cutting off the transformer, recording and storing the direction of the zero crossing point, and when the transformer is switched on, obtaining the specific voltage zero crossing point; detecting the power supply state of a power grid based on an AD sampling unit, and executing corresponding actions according to the power supply state of the power grid; and when the power grid recovers power supply, putting the load into the power grid based on the AD sampling unit when it is judged that the power grid operates stably. According to the invention, the transformer is cut off and input through active control at the specific voltage zero crossing point, so that the residual magnetism changes towards the attenuation direction along the residual magnetism curve, and the inrush current when the transformer is input is obviously reduced; and the H-bridge circuit is controlled by the single-chip microcomputer to output the primary side voltage of the transformer, so that the operation is flexible, and the control precision is high.

Description

Technical field [0001] The invention relates to the field of safety assurance of a distribution network automation system, and in particular to a method for suppressing an excitation inrush current applied to a power frequency transformer in a controllable inverter. Background technique [0002] Terminal backup power: When the main station issues a test call instruction, the grid collection terminal must be able to ensure that the current meter reading data is uploaded. The terminal backup can continuously and stably supply power to the collection terminal when the power grid is out of power to ensure that it can continue to receive meter reading instructions and realize real-time upload of meter reading data. However, due to the hysteresis characteristics of the magnetic core material of the transformer, there is residual magnetism in the magnetic core, and the magnetic flux density in the magnetic core cannot change suddenly when the power frequency transformer is closed, causi...

AI Technical Summary

Problems solved by technology

However, due to the inherent mechanical characteristics of the circuit breaker switch, there is often a delay in closing, which misses the best moment of closing and produces bias magnetism.

Moreover, the closing time of the phase selection closing technology is related to the residual magnetism in the magnetic core, but the residual magnetism in the transformer is difficult to measure, so there are still many inconveniences in the application

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