Open-circuit fault diagnosis method for MMC power device

A technology for open-circuit faults and diagnosis methods, applied in the directions of instruments, measuring devices, measuring electricity, etc., can solve the problems of increased hardware cost, short positioning time, long positioning time, etc., and achieve the effect of accurate and rapid detection and positioning, and easy engineering design.

Inactive Publication Date: 2017-06-23
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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Problems solved by technology

The method based on artificial intelligence algorithm is to use artificial intelligence algorithm (such as clustering algorithm and state machine) to diagnose faults. This method does not depend on the model and has strong robustness, but it has the disadvantages of large amount of calculation, long diagnosis time or increased hardware cost.
The method based on the system model is divided into the method based on the state observation and the method based on the switch model. The method based on the state observation is based on the MMC converter circuit model, establishes a mathematical expression, and performs fault det

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  • Open-circuit fault diagnosis method for MMC power device
  • Open-circuit fault diagnosis method for MMC power device
  • Open-circuit fault diagnosis method for MMC power device

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Embodiment Construction

[0051] The present invention will be described in further detail below in conjunction with the accompanying drawings, but the present invention is not limited by specific examples.

[0052] The structure of the modular multilevel converter based on the half-bridge sub-module is as follows: figure 1 As shown, each phase is formed by connecting the upper and lower bridge arms through two bridge arm inductors L, each bridge arm contains N sub-modules, and each sub-module consists of an energy storage capacitor and two power devices. Generally, there is a bypass switch T in the sub-module for bypassing the faulty sub-module. The submodule has three fault states: S 1 Fault, S 2 failure and both failures at the same time, since both failures at the same time have S 1 Fault and S 2 Fault characteristics during faults, so only S 1 Fault, S 2 failure. figure 2 Shown is a single-phase equivalent circuit diagram of a modular multilevel converter.

[0053] Such as image 3 The f...

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Abstract

The invention relates to an open-circuit fault diagnosis method for an MMC power device, and belongs to the technical field of large-power converter reliability. The method comprises a fault detection step and a fault locating step. During fault detection, a method based on an increment prediction model is used to detect whether an open-circuit fault occurs in the power device of a sub-module; and during fault location after occurrence of the fault, a method by comparing a capacitive voltage gradient of a sub-module is used to locate the sub-module with the fault. According to the method, influence of interference, sampling error and inaccurate model parameters on a diagnosis result is avoided, sub-module faults can be detected and located accurately rapidly within 4ms under different load conditions without adjustment of thresholds, and the capacitive voltage of the sub-module after faults is not increased.

Description

technical field [0001] The invention relates to a method for diagnosing an open-circuit fault of an MMC power device, belonging to the technical field of high-power converter reliability. Background technique [0002] Modular multilevel converter (MMC), because of its advantages of modularization, easy expansion, good output characteristics, and common DC bus, has been widely used in the field of medium and high voltage and high power, especially in the field of high voltage DC transmission. Extensive research and application. The MMC topology is composed of a large number of sub-modules, which leads to the low reliability of the MMC itself, but its application requires its high working reliability. Therefore, the problem of working reliability has become a very important practical problem in the industrial application of MMC. [0003] Fault diagnosis is one of the ways to improve the working reliability of MMC. Power devices are one of the most fault-prone components in ...

Claims

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Application Information

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IPC IPC(8): G01R31/02
CPCG01R31/50
Inventor 徐坤山谢少军袁小峰
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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