Starting method for current transformer

Abstract

The invention relates to a starting method for a current transformer, and is applied to the current transformer of which a main circuit is formed by sequentially connecting a direct current (DC)/DC conversion circuit and a DC/alternating current (AC) conversion circuit. A DC bus capacitor is arranged between the output end of the DC/DC conversion circuit and the input end of the DC/AC conversion circuit. The method comprises the following steps of: connecting an AC power grid with the DC end of the main circuit by a current limiting resistor, charging the DC bus capacitor by utilizing the AC power grid, regulating the main circuit to make the amplitude and phase of the output voltage of the main circuit are the same as those of the voltage of the AC power grid to meet grid connection requirements, and connecting the AC end of the main circuit to the AC power grid. By the starting method for the current transformer, not only relatively lower starting current is ensured to make radiation designing easier to realize, but also synchronous grid connection is realized to make grid connection impact current relatively lower; and the method is particularly applied to the starting of a DC double-channel or multi-channel current transformer.

Description

technical field [0001] The invention relates to a starting method of a converter in the technical field of power electronic conversion, in particular to a soft starting method for a DC-DC-AC converter. Background technique [0002] The existing soft-start method for the AC channel of the converter is mainly to connect a soft-start resistor in parallel with the grid-connected switch on the grid side. If the resistance value of the soft-start resistor is large, the soft-start current will be small. The voltage difference on both sides is large, and the inrush current is also large; if the resistance of the soft-start resistor is small, due to the existence of the AC filter capacitor and isolation transformer on the grid side, the soft-start current is large, and the heat dissipation requirements for the soft-start resistor Higher, or use a larger power soft-start resistor, which not only increases the size but also increases the cost. Contents of the invention [0003] In o...

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Problems solved by technology

[0002] The existing soft-start method for the AC channel of the converter is mainly to connect a soft-start resistor in parallel with the grid-connected switch on the grid side. If the resistance value of the soft-start resistor is large, the soft-start current will be small. The voltage difference on both sides is large, and the inrush current is also large; if the resistance value of the soft-start resistor is small, due to the existence of the AC filter capacitor and isolation transformer on the grid side, the soft-start current is large, and the heat dissipation requirements for the soft-start resistor Higher, or use a larger power soft-start resistor, which increases both the size and the cost

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