A Modular Capacitor Voltage Equalization Control Method for Modular Multilevel Converter

A modular multi-level, voltage equalization control technology, applied in the direction of converting AC power input to DC power output, electrical components, output power conversion devices, etc., can solve long aggregation time, large communication volume, control frequency increase, etc. problem, achieve the effect of reducing the time spent, increasing the control frequency, and overcoming the large amount of communication

Active Publication Date: 2016-01-20
深圳市奥特迅科技有限公司
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  • Application Information

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Problems solved by technology

Due to the large number of cascaded modules and the large number of output levels of modular multilevel converters in the field of power transmission (usually reaching tens to hundreds of levels), it is necessary to summarize the capacitor voltages of all modules of a bridge arm into one controller Sorting in the middle will generate a large amount of communication and lead to a long aggregation time, which limits the improvement of the control frequency

Method used

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  • A Modular Capacitor Voltage Equalization Control Method for Modular Multilevel Converter
  • A Modular Capacitor Voltage Equalization Control Method for Modular Multilevel Converter
  • A Modular Capacitor Voltage Equalization Control Method for Modular Multilevel Converter

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Embodiment 1

[0031] refer to figure 2 , image 3 and Figure 4 , the modular multilevel converter consists of 3 phases, and each phase contains 2 bridge arms. Suppose each bridge arm has M modules, and each phase has 2M modules. At any time, each phase contains two There are only M modules in each bridge arm to keep the DC side voltage constant. The input and removal of bridge arm modules are as follows: image 3 and Figure 4 As shown, the module capacitor is connected to the circuit and provides its own voltage when it is switched on, and it is equivalent to the module being short-circuited when it is cut off. When it is switched on, the module capacitor may be charged or discharged, and the direction of the charging current of the module is specified as the positive direction, such as image 3 (a) shown.

[0032] 1) It is assumed that each bridge arm has 200 modules, which are marked as SM1 to SM200 according to the actual physical connection sequence, and are divided into 10 gro...

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Abstract

The invention discloses a module capacitor voltage sharing control method for a modular multilevel converter. The method comprises the following steps of sequencing all modules in each group according to the magnitudes of module voltage values, and searching for a maximum module voltage value Umax(i) and a minimum module voltage value Umin(i) in each group, wherein i is 1, 2, ..., N; performing voltage sharing processing on the module voltage value of each module according to the maximum module voltage value and the minimum module voltage value in each group to obtain an estimated module voltage value of each group, extracting M corresponding estimated module voltage values from the estimated module voltage values U(i, j) of all the groups according to current directions of bridge arms, extracting the corresponding modules from each group according to the M extracted estimated module voltage values and the current directions of the bridge arms, and putting the extracted modules in all the groups into use, wherein the number of the M estimated module voltage values in each group is equal to that of the extracted modules in the group. According to the method, the communication traffic of a controller can be effectively reduced, and meanwhile, module voltage can be shared.

Description

technical field [0001] The invention belongs to the field of flexible direct current transmission, and in particular relates to a module capacitor voltage equalization control method of a modular multilevel converter. Background technique [0002] With the continuous development of DC transmission technology, the high-voltage DC transmission (VSC-HVDC) based on voltage source converters has unique advantages in the fields of renewable energy grid connection, passive network power supply, urban grid power supply, and asynchronous AC grid interconnection. Advantages are replacing traditional thyristor-based DC transmission methods. Modular multilevel converter (MMC) has become the most popular voltage source converter topology in the field of flexible HVDC transmission due to its modularity, easy expansion, and low harmonic content. [0003] When the modular multilevel converter is in normal operation, the capacitor voltage of the sub-modules should be kept balanced. The trad...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/483
Inventor 王跃丛武龙曹穆
Owner 深圳市奥特迅科技有限公司
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