Testing device and testing method of flexible direct-current transmission modular multilevel converter (MMC) converter valve operating

Abstract

The invention discloses a testing device and a testing method of flexible direct-current transmission modular multilevel converter (MMC) converter valve operating. Large current needing to be checked is produced through energy exchange between two groups of valve module submodule capacitors and a load electric reactor, accurate alternating current-direct current overlaying current stress can be obtained through respective adjustment of alternating component amplitude and phase difference of output voltage of two valve modules, and adjusting modes are simple and flexible. A charging source is only used for building working voltage of two sample valve submodules at the beginning of the test, energy supplementation power sources are used for building working voltage of two auxiliary valves at the beginning of the test, only less active loss is supplemented in the test process later, the two energy supplementation power sources respectively share one half of system loss, and requirements for power capacity of a test circuit are greatly lowered. In addition, the two energy supplementation power sources can offset harmonic waves of grid-connected current of the two energy supplementation power sources through difference of connection modes of transformers of the two energy supplementation power sources to a great degree, and harmonic wave pollution to power grids is reduced.

Description

Technical field [0001] The invention relates to the technical fields of flexible power transmission and distribution, power electronics, and user power for power systems, and specifically relates to a flexible direct current transmission MMC converter valve operation test device and test method. Background technique [0002] The modular multilevel converter (MMC) is formed by connecting several half-bridge or H-bridge IGBTs and capacitors in parallel to form sub-modules (SM) in a certain way. By separately controlling the input and removal status of each sub-module IGBT, the AC voltage output by the converter can be close to a sine wave, and efficient energy transmission can be realized. When the MMC valve is carrying out large-capacity transmission, it must operate at high voltage and high current for a long time. Its reliability is the key to the safe operation of the power system. It is extremely important to verify the performance of the converter by building a load environme...

AI Technical Summary

Problems solved by technology

[0009] The purpose of the present invention is to provide a flexible direct current transmission MMC converter valve operation test device, and at the same time provide a test method using the device to solve the difficulty of equivalent verification of the operating performance of the converter valve under actual working conditions in the prior art problems, so that the test valve assembly can withstand the continuous AC and DC current and steady-state voltage equivalent to the actual working conditions for a long time, and can fully assess the heating of the MMC valve assembly

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