Modular multilevel converter sub-module fault detection and location method and device

A modular multi-level, fault detection technology, applied in the direction of output power conversion device, AC power input conversion to DC power output, electrical components, etc., can solve the fault diagnosis and analysis of few modular multi-level converters And verification, application scenarios with a large number of modules that are not applicable, and damage to the consistency of the system structure, etc., to achieve the effect of reducing data collection costs, reducing the number of sub-modules, and reducing computing burdens

Active Publication Date: 2022-07-22
TIANJIN UNIV
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  • Abstract
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  • Claims
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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

Method used

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  • Modular multilevel converter sub-module fault detection and location method and device
  • Modular multilevel converter sub-module fault detection and location method and device
  • Modular multilevel converter sub-module fault detection and location method and device

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Embodiment 1

[0087] An energy layered control method for a multi-port medium and low voltage AC / DC hybrid microgrid, the method comprising the following steps:

[0088] Step 101: construct a modularized multilevel converter mathematical model, analyze the normal operation of the modularized multilevel converter submodule and the operating state under switching faults, and its impact on the converter output characteristics;

[0089] Step 102: Predict the output current and circulating current according to the established mathematical model;

[0090] Step 103: According to the predicted error between the output current and the actual value, and the predicted error between the circulating current and the actual value, the sub-module fault is detected, and the bridge arm where the fault is located is located at the same time;

[0091] Step 104: for the positioned bridge arm, extract the submodule with the highest capacitance voltage value in the bridge arm, and utilize the improved Laida crite...

Embodiment 2

[0094] The scheme in Embodiment 1 is further introduced below in conjunction with specific calculation formulas, drawings, and examples, and is described in detail below:

[0095] Step 201: construct a modularized multilevel converter mathematical model, analyze the normal operation of the modularized multilevel converter submodule and the operating state under switching faults, and its impact on the converter output characteristics;

[0096] like figure 1 As shown, the present invention takes the Double Star Chopper Cell (DSCC) MMC structure as the research object. DSCC type MMC contains three phase units, each phase unit includes upper bridge arm and lower bridge arm. Each bridge arm contains N half-bridge sub-modules and a bridge arm inductance (equivalent inductance L arm and the equivalent resistance R arm ). The coupling point between the upper bridge arm and the lower bridge arm passes through the filter inductance (equivalent inductance L eq and the equivalent res...

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Abstract

The invention discloses a method and device for fault detection and positioning of a modular multi-level converter sub-module, comprising: constructing a mathematical model of the modular multi-level converter, analyzing the normal operation and switching faults of the modular multi-level converter sub-module According to the established mathematical model, the output current and circulating current are predicted; according to the predicted output current and actual value error, the predicted circulating current and actual value error, the sub-module The fault is detected, and the bridge arm where the fault is located is located at the same time; for the located bridge arm, the sub-module with the highest capacitance voltage value in the bridge arm is extracted, and the abnormal value of the bridge arm is judged by the improved Laida criterion technology, so as to locate the fault. submodule. The detection and positioning method and device disclosed in the present invention can quickly locate module faults at different positions, and is not affected by the power reference step. It reduces the computational burden and improves the fault location speed.

Description

technical field [0001] The present invention relates to the technical field of multi-level converters, in particular to a method and device for fault detection and location of sub-modules of a modular multi-level converter. Background technique [0002] Modular Multilevel Converter (MMC) has the advantages of high modularity, strong expansibility, low switching frequency and good output voltage harmonic characteristics. However, MMC neutron modules are numerous 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 failures of power electronic converters are caused by the failure 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 metho...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/483H02M1/32
Inventor 肖迁李天翔贾宏杰穆云飞于浩霖余晓丹
Owner TIANJIN UNIV
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