Three-phase UPQC (Unified Power Quality Controller) topology circuit based on MMC (Multi Media Card)

Abstract

The invention discloses a three-phase UPQC (Unified Power Quality Controller) topology circuit based on a MMC (Multi Media Card) and belongs to the technical fields of flexible alternating-current power transmission and distribution in a power system and power electronics. The three-phase UPQC topology circuit comprises a parallel connection module, a series connection module, a power transmission line A-phase line, a power transmission line B-phase line, a power transmission line C-phase line, a first isolation transformer, a second isolation transformer and a third isolation transformer. The three-phase UPQC topology circuit has the beneficial effects that the parallel connection module of a unified power quality controller can be conveniently and directly suspended on a power transmission line of a medium and high voltage power distribution system without a transformer, so that the equipment investment and the equipment loss are reduced, and the space is saved; through a modular design, the redundancy of a device can be conveniently improved, and the running reliability of the device can be increased; and standardized and socialized mass production is also facilitated, so that the production period of equipment is shortened, and the production cost of the equipment is further reduced.

Description

technical field [0001] The invention belongs to the technical fields of flexible alternating current transmission and distribution of power systems and power electronics, and in particular relates to an MMC-based three-phase UPQC topology circuit. Background technique [0002] Modern industrial, commercial and residential electrical equipment, such as high-performance office equipment, precision experimental instruments, frequency conversion speed control equipment, programmable logic controllers, various automatic production lines, and computer systems, are increasingly sensitive to changes in power characteristics. The requirements for power quality are constantly increasing. [0003] The research on power quality control technology has huge economic and social benefits, and is a hot spot in the field of electric power research. The hazards of power quality problems such as voltage swell, voltage sag, three-phase unbalanced voltage, harmonic voltage, reactive current, har...

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Problems solved by technology

In these two methods, the parallel side needs to be connected to the system through a transformer, which increases the production cost and land occupation requirements of the equipment, and also increases the loss of the equipment.

In addition, the first method limits the working voltage of the converter due to the limitation of the withstand voltage and current capacity of the switching device, thus limiting the application space of the unified power quality controller with higher voltage and larger capacity.

In the second method, due to the use of a special multi-winding transformer, there are many connecting lines between the transformer and the H-bridge, and the internal structure of the device is complicated, and this complexity will become more complicated with the increase of voltage and capacity, which is not conducive to Production and daily maintenance also limit the application of this structure in higher voltage and larger capacity

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