Industrial frequency transformer inrush current suppression strategy applied to controllable inversion

Abstract

The invention discloses an industrial frequency transformer inrush current suppression strategy applied to controllable inversion. According to the technical scheme, the strategy comprises the steps that 1, on the primary side of an industrial frequency transformer, a single-chip microcomputer is adopted to control an H-bridge circuit to output industrial frequency voltage; 2, soft starting is carried out to prevent inrush current from being generated during initial starting; and 3, the transformer is cut off at the zero crossing point of the primary side voltage of the industrial frequency transformer, the voltage direction change state of the zero crossing point is recorded, and when the transformer is switched on again, the voltage direction change continues switching-off state. According to the invention, by actively controlling the zero crossing point state of the primary side voltage removal and input of the transformer, residual magnetism is changed towards attenuation directionalong residual magnetism curve, so that inrush current when transformer is input is obviously reduced; and the single-chip microcomputer is used for controlling the H-bridge circuit to output the primary side voltage of the transformer, and the closing time of a circuit breaker and the residual magnetism of an iron core of the circuit breaker in a traditional strategy do not need to be considered, so that operation is flexible, and the control precision is high.

Description

Technical field [0001] The invention relates to the field of safety assurance of distribution network automation systems, and relates to a power frequency transformer excitation inrush current suppression strategy applied to a controllable inverter. Background technique [0002] Terminal backup power: At present, most of the power consumption information collection terminals in the field of distribution network automation are directly powered by the power grid. Once the power grid is cut off, the collection terminal will not work normally. The terminal backup equipment can invert the DC power in the backup power supply into AC power that meets the requirements when the power grid is cut off, and stably supply power to the collection terminal to ensure that it can continue to perform meter reading normally. [0003] Excitation inrush current: Excitation inrush current refers to the transient current generated in the windings of the transformer due to the nonlinear saturation charact...

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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