MMC, MMC sub-module and MMC sub-module bypass protection method
A bypass protection and sub-module technology, applied in the direction of power transmission and AC network, can solve the problems affecting the reliable and stable operation of the DC power transmission system, and achieve the effect of improving reliability and stability, ensuring operation safety, and preventing capacitor overvoltage.
Inactive Publication Date: 2019-04-09
XUJI GRP +2
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Problems solved by technology
[0004] The purpose of the present invention is to provide a kind of MMC, MMC sub-module and MMC sub-module bypass protection method, in order to solve the existing sub-module failure and bypass switch to block all sub-modules to protect and affect the reliability and stability of the direct current transmission system run problem
[0005] In order to realize the fault protection of sub-modules, solve the problem that when the bypass switch of the existing sub-modules refuses to operate, the protection by blocking all sub-modules affects the reliable and stable operation of the DC transmission system
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[0022] The present invention will be described in further detail below in conjunction with the accompanying drawings.
[0023] method embodiment
[0024] The present invention provides a kind of MMC submodule bypass protection method, such as figure 1 shown, including the following steps:
[0025] (1) When a sub-module fails, control the corresponding bypass switch to close. This step is an existing technical means, and can be realized through the existing technology.
[0026] (2) Detect whether the bypass switch is closed.
[0027] In this step, the detection of whether the bypass switch is closed, for example, the displacement signal can be acquired through the displacement sensor, and the detection of whether the bypass switch is closed or not can be realized through the judgment of the stroke; another example, by detecting the branch where the bypass switch is located , by judging whether the branch is conducting to realize the detection of whether the bypass switch is...
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The invention relates to an MMC, an MMC sub-module and an MMC sub-module bypass protection method. The MMC comprises a three-phase six-bridge arm topological structure, wherein each bridge arm comprises at least two MMC sub-modules which are cascaded, at least one of the MMC sub-modules in each MMC sub-module comprises a sub-module body topological structure and a bypass switch, a bidirectional controlled switch is arranged in parallel at two ends of the bypass switch, the bypass switch is controlled to be closed when a fault occurs in the sub-module, whether the bypass switch is switched offis detected, the bidirectional controlled switch is controlled to be conducted if the bypass switch is not closed, the bidirectional controlled switch is controlled to be conducted when the fault of the sub-module occurs and the corresponding bypass switch is refused to move, the function which is achieved by the rejected bypass switch is achieved, the phenomena of overvoltage of a sub-module capacitor, IGBT breakdown even fire on the sub-module are prevented, the running safety of the sub-module is ensured, and the reliability and the stability of a DC power transmission system are improved.
Description
technical field [0001] The invention relates to the technical field of direct current transmission, in particular to an MMC, an MMC sub-module and a bypass protection method for an MMC sub-module. Background technique [0002] With the development of power electronics technology, DC transmission systems based on modular multilevel converters (MMCs) have developed rapidly. The modular multilevel converter is composed of thousands of sub-modules, and each sub-module includes a DC support capacitor, an IGBT and its driver, and a high-speed bypass switch. The control of the high-speed bypass switch can be controlled by a controller. [0003] When any sub-module fails to operate the bypass switch, the bridge arm where the faulty sub-module is located will form an open circuit, resulting in an unbalanced current in the three-phase bridge arm of the system; Charging, if the sub-module fails, the control bypass switch is turned on, and the faulty sub-module is bypassed. However, wh...
Claims
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Login to View More IPC IPC(8): H02J3/36
CPCH02J3/36Y02E60/60
Inventor 胡四全范彩云常忠廷王梁夏克鹏李娟周辉张坤
Owner XUJI GRP