Single-phase/three-phase dual-use three-level low-frequency drying power supply

Abstract

The invention discloses a single-phase / three-phase dual-use three-level low-frequency drying power supply, comprising a heating power supply. The input end of the heating power supply is connected with a master control unit; the output end of the heating power supply is connected with a single-phase transformer or a three-phase transformer; the heating power supply is formed by serially connectingfour current source modules to four sub-control units prior to parallel connection; each current source module is formed by parallelly connecting four NPC three-level circuits; each NPC three-level circuit is controlled to output single-phase or three-phase mode via a single-phase / three-phase changeover switch; the master control unit generates a current command and an alternating operation clocksignal into the current source modules; the sub-control units corresponding to the current source modules generate driving signals to control current and voltage outputting. The single-phase / three-phase dual-use three-level low-frequency drying power supply has high heating power and wide range of application, can provide single-phase / three-phase outputting, and can dry large-sized power transformers.

Description

technical field [0001] The present invention relates to the technical field of low-frequency dry power supply, and more specifically, relates to a single / three-phase dual-purpose three-level low-frequency dry power supply. Background technique [0002] During the on-site installation of the transformer, it is very important to prevent the transformer from getting wet. In recent years, the rising trend of the voltage level and single capacity of the transformer is very obvious. In order to make the high-voltage level and large-capacity transformer meet the requirements of insulation and dry operation safely, and prolong its service life as much as possible, the drying and dehumidification technology of the transformer is a critical question. [0003] At present, the moisture of commonly used transformers is mainly gathered in insulating cardboard and transformer oil, and these two parts are the main insulating materials of transformers, so their moisture content is of great ...

AI Technical Summary

Problems solved by technology

However, this patent only uses one three-level inverter module to complete the dry power supply, and problems such as insufficient power and current ripple will occur when dealing with large oil-immersed transformers

Moreover, most of the main transformers in ultra-high voltage and ultra-high voltage substations are single-phase transformers. This solution can only achieve three-phase output, which cannot meet the requirements of on-site drying of ultra-high voltage and ultra-high voltage transformers.

However, if the dry power supply is only designed for large single-phase transformers, it will cause problems of narrow application range and waste of resources

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