MMC fault detection method based on fast Fourier transform and sliding average value algorithm

Abstract

The invention provides an MMC fault detection method based on a fast Fourier transform and a sliding average value algorithm. The MMC fault detection method based on the fast Fourier transform and thesliding average value algorithm comprises the following steps that each phase current on the alternate-current side of a modular multilevel converter to be detected in an operating state is collected, the current is processed through the fast Fourier transform to obtain a direct current component in each current period, whether the modular multilevel converter to be detected has a submodule open-circuit fault or not is judged according to the magnitude of the direct current component and a preset direct current component threshold value, a direct-current component of a three-phase current iscompared to locate the faulty bridge arm, and then the capacitor voltages of all sub-modules of the faulty bridge arm are processed and analyzed by a sliding average value filtering algorithm to locate faulty sub-modules. According to the MMC fault detection method based on the fast Fourier transform and the sliding average value algorithm, a simple algorithm is utilized under the condition that an accurate data model does not need to be established, faults are quickly and accurately monitored under the condition that no additional sensors are needed, and the method is simple and easy to implement.

Description

technical field [0001] The invention relates to the field of power electronics technology and flexible direct current transmission, in particular to a submodule IGBT open-circuit fault detection method of a modular multilevel converter based on fast Fourier transform and submodule voltage sliding average algorithm. Background technique [0002] As a new type of voltage source converter, the modular multilevel converter (MMC) is composed of a large number of sub-modules connected in series. It has many advantages such as high modularity, low harmonics, and low loss. The frequency can obtain better waveform quality, and it has been widely used in high-voltage and high-power occasions such as flexible direct current transmission. [0003] MMC has 6 bridge arms in total, and each bridge arm is composed of N submodules (Submodule, SM) with the same structure and a bridge arm reactor L0 connected in series. The upper and lower bridge arms of each phase form a phase unit, and share...

AI Technical Summary

Problems solved by technology

However, the open circuit fault of the sub-module IGBT is not easy to be found, and it is likely to form a secondary fault. Therefore, it is particularly important to detect the open circuit fault of the MMC system

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