On-load tap-changer single-resistor symmetrical transition circuit and voltage regulating method

Abstract

The invention discloses an on-load tap-changer single-resistor symmetrical transition circuit and a voltage regulation method. The transition circuit comprises a first main contact, a second main contact, a main vacuum contact, a first auxiliary vacuum contact, a second auxiliary vacuum contact, a first isolation switch, a second isolation switch, a change-over switch and a transition resistor. Two auxiliary switch elements exist in the transition circuit, interpolar ring current in the on-load switching process is switched on and off in turn, the switching process is symmetrical, the two auxiliary switch elements are consistent in current switching-on and switching-off tasks, the switching loss of the auxiliary switch elements is reduced, and the switching capacity of the main switch element and the switching capacity of the auxiliary switch elements can be balanced; only one transition resistor is used in the transition circuit, so that design and installation are facilitated, and the insulation distance is ensured; the two isolation switches are designed, so that an electrical isolation effect can be achieved, the isolation switches can be used as protection switches of auxiliary switch elements, and the fault that current cannot be cut off after the auxiliary switch elements fail is prevented.

Description

technical field [0001] The invention relates to the technical field of on-load tap changers, in particular to an on-load tap-changer single-resistance symmetrical transition circuit and a voltage regulation method. Background technique [0002] The on-load tap-changer is a key component inside the power transformer, which can operate under the excitation or load state of the transformer, and change the effective turns ratio by changing several taps connected to the transformer winding to realize regulation without interrupting the load current The output voltage. On-load tap-changers are widely used, especially in converter transformers of UHV DC transmission projects, to ensure the rated firing angle of the converter during normal operation. Most of the on-load tap-changers equipped with early power transformers used the principle of high-speed resistance switching, and the load switching was performed by copper-tungsten arc contacts. This type of oil-immersed non-vacuum ...

AI Technical Summary

Problems solved by technology

In the actual UHV DC transmission project, the load current flowing through the on-load tap changer of the converter transformer is about 500-600A, and the inter-stage circulating current flowing through the transition resistance during the switching process is about 900-1000A. The breaking circulating current is significantly greater than the load current breaking the main on-off switching element, resulting in unbalanced breaking tasks between the auxiliary switching element and the main on-off switching element

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