Voltage-sharing control method during pole-to-ground fault ride-through period of modular multilevel converter

A modular multi-level, fault ride-through technology, applied in the direction of AC network voltage adjustment, AC power input conversion to DC power output, electrical components, etc. , to minimize the circulating current, reduce the amplitude, and reduce the operating loss

Pending Publication Date: 2022-06-17
HANGZHOU DIANZI UNIV
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However, this method is based on the indirect modulation method, which is not commonly used in practical engineering
[0007] To sum up, neither o

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  • Voltage-sharing control method during pole-to-ground fault ride-through period of modular multilevel converter
  • Voltage-sharing control method during pole-to-ground fault ride-through period of modular multilevel converter
  • Voltage-sharing control method during pole-to-ground fault ride-through period of modular multilevel converter

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[0030] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as there is no conflict with each other.

[0031] The MMC with fault ride-through capability involved in the present invention specifically includes three phases a, b and c, each phase is composed of upper and lower bridge arms, and each bridge arm has a negative level output capability greater than half of the rated DC voltage. The converter topologies that meet the requirements include full-bridge MMC, hybrid MMC of half-bridge and full-br...

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Abstract

The invention discloses a voltage-sharing control method in a pole-to-ground fault ride-through period of a modular multilevel converter. The method comprises the following steps: firstly, detecting electrical quantity of an MMC AC-DC side in real time, and judging whether a DC pole-to-ground fault occurs or not; when it is detected that a direct-current pole-to-ground fault occurs, the MMC is immediately switched to a pole-to-ground fault ride-through control strategy, and meanwhile, a fundamental frequency feed-forward compensation item FD is superposed on a circulating current suppressor control instruction; and completing the balance of the capacitor voltage according to the loop current suppressor control instruction after the superposition of the fundamental frequency feed-forward compensation item. Complex additional control does not need to be added, and the capacitor voltage balance of the upper and lower bridge arm sub-modules can be realized only by superposing a fundamental frequency ring current feed-forward item on an existing ring current suppressor control instruction; according to the method, the capacitor voltage balance of the upper and lower bridge arm sub-modules of the MMC in the pole-to-ground fault ride-through period can be effectively maintained, and the circulation can be minimized, so that the amplitude of the bridge arm current is reduced, and the operation loss of the MMC is reduced.

Description

technical field [0001] The invention belongs to the field of flexible direct current transmission system control and protection, and more particularly relates to a sub-module capacitor voltage equalization control method of a modular multilevel converter MMC (Modular Multilevel Converter) during pole-to-ground fault ride-through. Background technique [0002] In recent years, flexible DC transmission technology based on modular multilevel converter MMC has been developed rapidly. However, when overhead transmission lines are used in DC transmission lines, pole-to-ground faults occur frequently. This fault will make the sound pole of the MMC and the neutral point of the AC side face a huge voltage stress, which will seriously endanger the operation of the system. [0003] In order to solve the above problems, the academic community proposes a pole-to-ground fault ride-through control method. By adjusting the reference voltage of the faulty pole bridge arm, the voltage stres...

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Application Information

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IPC IPC(8): H02J3/40H02J3/12H02M7/483H02M7/5387
CPCH02J3/40H02J3/12H02M7/483H02M7/53871
Inventor 何震曾平良杭丽君刘燕华秦晓辉苏丽宁
Owner HANGZHOU DIANZI UNIV
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