Low Frequency Model Predictive Control Method Based on Hybrid Modular Multilevel Converter

A modular multi-level, model predictive control technology, applied in the direction of multi-phase network asymmetry reduction, AC power input conversion to DC power output, electrical components, etc., to suppress circulating current, clear physical model, and reduce system switching frequency Effect

Active Publication Date: 2019-12-03
SHANGHAI UNIVERSITY OF ELECTRIC POWER
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, model predictive control is widely used in traditional MMC, but the application in hybrid MMC system still needs further research

Method used

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  • Low Frequency Model Predictive Control Method Based on Hybrid Modular Multilevel Converter
  • Low Frequency Model Predictive Control Method Based on Hybrid Modular Multilevel Converter
  • Low Frequency Model Predictive Control Method Based on Hybrid Modular Multilevel Converter

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Embodiment Construction

[0024] Based on the low-frequency model predictive control method of hybrid modular multilevel converter, based on the discrete state model of the system, the inputs of the upper and lower bridge arm modules are used as control variables, and the AC current, circulating current and sub-module capacitor voltage are hierarchically controlled . First, use the AC current index function to select the optimal switch state combination; secondly, use the circulating current index function to adjust the input number of sub-modules of the upper and lower bridge arms; combine the working status of the full-bridge module to determine the final input number of sub-modules; finally calculate the phase The difference in the number of sub-module inputs at adjacent moments, and the optimal voltage equalization strategy is used to realize the balanced control of the sub-module capacitor voltage, which reduces the number of sub-module switching operations and effectively reduces the switching fre...

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Abstract

The invention relates to a low frequency model prediction control method based on a hybrid modular multi-level current converter. Each bridge arm is equipped with N sub modules, namely, semi-bridge modules, and one full bridge module. The capacitor voltage of the full bridge module is assigned as a half of each sub module. The low frequency model prediction control method concretely includes taking upper and lower bridge arm module input number as a control variable, performing layering control on AC current, loop current and capacitor voltage of the sub modules and selecting the optimal switch state combination by utilizing an AC current index function; adjusting the sub module input number of the upper bridge and the lower bridge arms by adopting a loop current index function; determining the final sub module input number through combination with the working state of the full bridge module; and finally calculating the sub module input number difference of neighboring time points, adopting an optimization voltage-sharing strategy for realizing balance control of the capacitor voltage of the sub modules, so that the system switching frequency is reduced. The method is clear in physical model and does not need to consider complex parameter setting and weight index design. Digital control is easy to realize and optimizing computation workload is reduced.

Description

technical field [0001] The invention relates to the field of power electronics, in particular to a low-frequency model predictive control method based on a hybrid modular multilevel converter. Background technique [0002] In recent years, with the rapid development of power electronics technology, multilevel converters have been more researched and applied. As a new type of multilevel converter, the modular multilevel converter is widely used in long-distance flexible DC transmission due to its modular structure, easy expansion of capacity, low harmonic content, and flexible power adjustment capabilities. , reactive power compensation, new energy power generation and other high-voltage and high-power occasions, it has broad development prospects. Due to the many favorable characteristics of MMC, MMC topology, control method and modulation strategy, capacitor voltage balance control and circulation suppression have become one of the hotspots of scholars' in-depth research. ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/26H02J3/01H02M7/00H02M7/5387
CPCH02J3/01H02J3/26H02M7/00H02M7/53873Y02E40/40Y02E40/50
Inventor 杨兴武雷彪陈磊王楠楠陈秀秀李豪季亮
Owner SHANGHAI UNIVERSITY OF ELECTRIC POWER
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