Flux linkage control-based transformer and excitation surge suppression method

Abstract

The invention discloses a flux linkage control-based transformer and an excitation surge suppression method. A small-capacity DC / AC converter is connected to a secondary winding or an auxiliary winding of the transformer, a voltage phase of a power grid at a primary side is detected before no-load closing, and a reference instruction of iron core flux linkage is derived according to a relation between a winding voltage and the iron core flux linkage. An iron core flux linkage closed-loop PI control system is built under a synchronous rotating reference system, so that an output voltage of theconverter is controlled, zero-error tracking of the iron core flux linkage on a flux linkage reference value is performed, and sine synchronous flux linkage having phase difference with the power gridvoltage being 90 degrees can be built in advance in an iron core before no-load closing. By the measure, the iron core flux linkage is directly in a steady state without transient process no matter when the transformer is closed, so that the excitation surge can be thoroughly eliminated.

Description

technical field [0001] The invention belongs to the technical field of transformers and relates to suppression of transformer excitation inrush current. Background technique [0002] When the transformer is closed and connected to the power grid with no load, the iron core flux linkage often includes the corresponding DC component (DC bias) in addition to the sinusoidal steady-state component. When the bias is large, the iron core will often be saturated and cause an excitation inrush current. . Although the excitation inrush current does not last long, it can often reach 6-8 times the rated current, which will cause the protection device to malfunction. For this reason, many scientific and technological workers have conducted research on the detection and identification of inrush current in order to avoid the malfunction of relay protection devices. In fact, the magnetizing inrush current has great harm to the sensitive equipment in the power grid. In addition, the harmo...

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Problems solved by technology

However, the actual transformer is generally closed by a vacuum circuit breaker, and its closing time has a large dispersion, and it is difficult to achieve accurate phase control

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