MMC sub module open-circuit fault diagnosis method

A technology of open-circuit fault and diagnosis method, which is applied in the direction of circuit breaker testing, etc., can solve the problems of easy damage of switching elements, high failure rate, and affecting the output characteristics of sub-modules, and achieve a strong robustness effect

Active Publication Date: 2018-11-23
ZHEJIANG UNIV
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Problems solved by technology

The above-mentioned advantages of MMC come from its cascaded structure of sub-modules. However, a large number of cascaded sub-modules contained in MMC also constitute a large number of potential failure points, which poses a great challenge to the operational reliability of MMC.
The sub-modules used in MMC are usually composed of swit

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  • MMC sub module open-circuit fault diagnosis method
  • MMC sub module open-circuit fault diagnosis method
  • MMC sub module open-circuit fault diagnosis method

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Embodiment Construction

[0057] In order to describe the present invention more specifically, the technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0058] Such as figure 1 As shown, the basic unit of a single-ended three-phase modular multilevel converter (MMC) is a sub-module (Sub-Module, SM), N SM Two sub-modules are cascaded and a bridge arm inductor is connected in series to form a bridge arm, and the upper and lower bridge arms are connected in series to form a phase unit. The three-phase MMC converter contains three phase units, 6 bridge arms, 6N SM sub-module, the DC side bus voltage is U dc , the three-phase phase voltages on the AC side are respectively u a , u b and u c , O point is the reference point of zero potential.

[0059] In this embodiment, MMC adopts such as figure 2 The MMC half-bridge sub-module structure shown, the sub-module structure includes two IGBT tubes S 1 , S ...

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Abstract

The present invention discloses an MMC sub module open-circuit fault diagnosis method. The method comprises the steps of: constructing a random matrix based on a sub module capacitive voltage value, employing a monocyclic theorem to analyze the distribution of feature values of the random matrix to determine the operation state of the MMC; if the sub module open-circuit faults are detected, performing statistic analysis of the sub module capacitive voltage of a fault bridge to locate a fault sub module. The MMC sub module open-circuit fault diagnosis method can be compatible with single/multi-sub module open-circuit fault diagnosis, the used sub module capacitive voltage value has been existed in the current MMC control system so as not to need extra hardware resources. Besides, the faultdiagnosis is completed based on data analysis without depending on an MMC analysis model so as not to be sensitive to the nondeterminacy of system parameters, and therefore, the MMC sub module open-circuit fault diagnosis method has high robustness.

Description

technical field [0001] The invention belongs to the technical field of flexible DC power transmission and distribution, and in particular relates to a method for diagnosing an MMC sub-module open-circuit fault. Background technique [0002] Since the advent of Modular Multilevel Converter (MMC) in 2002, it has increasingly become a high-voltage DC (High-voltage DC) One of the most promising converter topologies in Voltage Direct Current (HVDC) transmission systems. The above-mentioned advantages of MMC come from its cascaded structure of sub-modules. However, a large number of cascaded sub-modules contained in MMC also constitute a large number of potential failure points, which poses a great challenge to the operational reliability of MMC. The sub-module used by MMC is usually composed of switching elements and passive components. Compared with passive components, switching elements are more fragile and more easily damaged, and are the components with the highest failure r...

Claims

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Application Information

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IPC IPC(8): G01R31/327
Inventor 李武华周维浩陈宏杨贺雅罗皓泽何湘宁
Owner ZHEJIANG UNIV
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