Method and device for detecting and positioning faults of sub-modules of modular multilevel converter

Abstract

The invention discloses a modularized multi-level converter sub-module fault detection positioning method and device, and the method comprises the steps: constructing a modularized multi-level converter mathematical model, and analyzing the operation states of a modularized multi-level converter sub-module under the conditions of normal work and switch fault, and the influence of the operation states on the output characteristics of a converter; predicting an output current and a circulating current according to the established mathematical model; according to the error between the predicted output current and the actual value and the error between the predicted circulating current and the actual value, detecting a sub-module fault, and positioning a bridge arm where the fault is located; and for the positioned bridge arm, extracting the sub-module with the highest capacitor voltage value in the bridge arm, and judging the abnormal value of the sub-module by using the improved Pauta criterion technology, thereby positioning the sub-module with the fault. According to the detection positioning method and device disclosed by the invention, module faults at different positions can be quickly positioned without being influenced by a power reference step, and the number of sub-modules needing to be judged can be reduced by positioning the bridge arm where the fault is located, so that the calculation burden of module fault positioning is reduced, and the fault positioning speed is improved.

Description

technical field [0001] The present invention relates to the technical field of multilevel converters, in particular to a method and device for detecting and locating submodules of modular multilevel converters. Background technique [0002] Modular Multilevel Converter (MMC) has the advantages of high modularity, strong expandability, low switching frequency and good output voltage harmonic characteristics. However, there are many sub-modules in the MMC, and the topology contains a large number of switching devices, which increases the risk of switching failures. According to statistics, more than 38% of the faults in power electronic converters are caused by the faults of semiconductor power devices. Therefore, the fault diagnosis technology of switching devices has important application significance, and has gradually become the focus of power electronic power converter technology. MMC usually contains a large number of switching devices, and the proposed method of switc...

AI Technical Summary

Problems solved by technology

[0005] 1. The existing hardware-based fault diagnosis technology can provide faster fault location speed, but its hardware cost is relatively high, or additional sub-module voltage sensors need to be installed, which destroys the consistency of the system structure, and is subject to great influence in practical applications. large limit;

[0006] 2. Existing software-based fault diagnosis technology relies on model accuracy and has a large amount of calculation, so it is not suitable for application scenarios with a large number of modules; 3. In the prior art, there are few modular multi-level technologies for grid-connected application scenarios Converter fault diagnosis analysis and verification

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