A voltage transformer neutral point direct current suppression apparatus test system

Abstract

The invention relates to a voltage transformer neutral point direct current suppression apparatus test system comprising a direct current charging unit, an alternating current charging unit, a trigger valve Vaux, an output terminal and a grounding terminal. One terminal of the alternating current charging unit and one terminal of the direct current charging unit are connected to the output terminal through the trigger valve Vaux. The output terminal is used for connection to a high-voltage terminal test device TO. The other terminal of the alternating current charging unit and the other terminal of the direct current charging unit are connected to the grounding terminal. The grounding terminal is used for grounding after being connected to a grounding terminal of the test device. The direct current charging unit is composed of an LC resonance circuit and a direct current switching mode convertor circuit. The alternating current charging unit is composed of an LC resonance circuit and an alternating current switching mode convertor circuit. A recombination current corresponding to an actual working condition is generated by means of recombining an alternating current with a direct current. The recombination current is then applied to the test device to carry out corresponding examining, so that testing of the current and voltage stress of a voltage transformer neutral point direct current suppression apparatus is realized.

Description

technical field [0001] The invention belongs to the field of testing, and in particular relates to a testing system for a neutral point direct current suppressing device of a transformer. Background technique [0002] When the DC transmission system operates in the single-pole ground return mode, it will cause a DC potential near the ground electrode of the DC transmission system converter station, which is determined by the magnitude of the DC current injected into the ground electrode and the soil resistivity. The injection current is the DC transmission current, and the higher the soil resistivity, the higher the potential, and the wider the range of influence. The high potential of the DC grounding electrode will affect the ground grid potential of the AC substation, causing a DC current to flow through the transformer running at the neutral point of the AC substation; that is, it is equivalent to shunting part of the DC transmission current, and the DC current flowing t...

AI Technical Summary

Problems solved by technology

Harmonics lead to distortion of the system voltage waveform of the AC system, continuous overvoltage when the long line is closed with no load, relay protection malfunction, filter overload, increase in latent power supply current during single-phase reclosing, and increase in circuit breaker recovery voltage

DC bias can also lead to an increase in transformer excitation current, an increase in reactive power consumption by the transformer, overloading of the reactive power compensation device of the system or a drop in the system voltage

Another consequence of transformer bias saturation is to cause noise and vibration, and at the same time increase the active power loss of the transformer, which may cause local overheating of the transformer and cause damage

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