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Control Method of Energy Balance Between Bridge Arms of Modular Multilevel Converter

A modular multi-level, energy-balancing technology, applied in collectors, AC network load balancing, electric vehicles, etc., can solve problems such as transmission power fluctuations, threats to the safety of converters, and positive and negative pole imbalances. Effects of optimization and transformation, improvement of anti-disturbance performance and dynamic performance

Active Publication Date: 2017-06-09
SHANGHAI JIAOTONG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, this document does not control the balance of the capacitor voltage sum of each bridge arm. When the system is connected to a weak AC grid, the transmission power fluctuations are prone to unbalanced positive and negative poles, which threatens the safety of the converter.

Method used

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  • Control Method of Energy Balance Between Bridge Arms of Modular Multilevel Converter
  • Control Method of Energy Balance Between Bridge Arms of Modular Multilevel Converter
  • Control Method of Energy Balance Between Bridge Arms of Modular Multilevel Converter

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Experimental program
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Embodiment

[0041]This embodiment provides a method for controlling energy balance between bridge arms of a modular multilevel converter, in which a control signal is superimposed on the basis of an existing control strategy to realize energy balance control of capacitor storage between bridge arms. The control method provided in this embodiment includes the capacitor energy storage calculation link (realized by the capacitor energy storage calculation module), the energy balance control link (realized by the energy balance control module) and the balance signal calculation link (realized by the balance signal calculation module), specifically Including the following steps:

[0042] The first step is to use the capacitor energy storage calculation module to calculate the energy stored in the capacitor. The input terminals of the capacitor energy storage calculation module are respectively connected to the average value signal of the capacitor voltage of the upper arm of the phase A and th...

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Abstract

The invention provides a method for controlling the energy balance between the bridge arms of a modular multilevel converter, which superimposes the energy balance control component between the bridge arms in the output modulation signal of the existing control system, and is compatible with the existing control strategy and the internal voltage of the bridge arms The balance control method is combined to improve the system stability under the condition of weak AC system connection and transmission power fluctuation. In the control method, the energy difference between the upper and lower bridge arms is calculated by the PI regulator to obtain the given amplitude of the circulating current, and the PR regulator is used to control the modular multi-level circulating current to track the given signal of the fundamental frequency circulating current, and the calculated value of the PR regulator is obtained The balance component is superimposed with the modulation signal of the original system to realize the energy balance control between the upper and lower bridge arms, which helps to improve the system stability.

Description

technical field [0001] The present invention relates to the technical field of multi-level flexible direct current transmission converter control, in particular, to a modular multi-level converter bridge-arm energy storage control based on a modular multi-level topology converter capacitor energy storage Balance control method. Background technique [0002] Flexible DC transmission technology has been widely used in offshore wind farm grid-connected systems. With the continuous expansion of offshore wind farms, the voltage level and capacity requirements of flexible DC transmission converters are also increasing. At the same time, some power grids in coastal areas and other areas are weak AC. system, which puts forward higher requirements for the control of the converter. [0003] Modular multilevel converters are based on modular power units and adopt a multi-level series structure to increase the system voltage level. Currently, commonly used power unit topologies include...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J7/00H02J3/28H02M1/12
Inventor 吴杰王志新
Owner SHANGHAI JIAOTONG UNIV