Improved modular multilevel transverter submodule topology
A modular multi-level, inverter technology, applied in the field of power transmission and distribution, can solve the problems of lack of DC side short-circuit current blocking ability, low failure rate, slow response speed, etc.
Inactive Publication Date: 2014-07-02
NORTH CHINA ELECTRIC POWER UNIV (BAODING) +2
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Problems solved by technology
Since the modular multilevel converter mostly adopts the half-bridge sub-module topology, when a fault occurs on the DC side, although all the insulated gate bipolar transistors (Insulated Gate Bipolar Transistor, IGBT) can be blocked, due to the antiparallel connection of the IGBT The freewheeling diode provides a path for the short-circuit current, so that the short-circuit current cannot be blocked, so that it does not have the ability to block the short-circuit current of the DC side
However, the current high-voltage and large-capacity DC circuit breaker manufacturing process is not yet mature, and it is rarely used in high-voltage and large-capacity occasions. Therefore, DC side faults can only be cut off by switching off the AC circuit breaker at the converter station, but the system response speed of this method Slower, complex timing of restart coordination actions, longer recovery time
In order to reduce the probability of faults on the DC side of the system, the current DC transmission project has to use low-failure and expensive DC cables as the transmission medium, which limits the application of low-cost overhead lines
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[0010] The topology of the series twin sub-modules will be described in detail below with reference to the accompanying drawings.
[0011] figure 1 It is an improved modular multilevel converter sub-module topology proposed by the present invention. The IGBT T5 acts as a boot switch and works in a normally-on state, which is equivalent to a short circuit, while the diode D6 is in a reverse biased state due to the voltage across the capacitor C1, which is equivalent to an open circuit.
[0012] figure 2 In the case of a serious fault on the DC side, when the system blocks all IGBTs, the current flow path of the bridge arm. When the bridge arm current is greater than zero, the capacitors C1 and C2 in the module are connected in series and are in a charging state, and the output voltage of the module is 2Uc. When the bridge arm current is less than zero, only C1 in SM1 is in the charging state because SM2 is in the cut-off state, and the output voltage of the module is -Uc at...
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The invention discloses an improved modular multilevel transverter submodule topology which is applied to the technical field of power transmission and distribution. According to the technical scheme, under the premise of not changing the series connection mode among submodules in traditional modular multilevel transverters, half bridge submodule topology is improved and a tandem twin submodule topology is designed. The improved modular multilevel transverter submodule topology is applied to modular multilevel voltage source transverters, and when a fault occurs at a direct current side, the direct current fault current blocking ability is obtained, and the alternating current circuit breaker motion is avoided.
Description
technical field [0001] The invention belongs to the technical field of power transmission and distribution, and relates to an improved sub-module topology of a modularized multilevel converter. [0002] Background technique [0003] The Modular Multilevel Converter (MMC) adopts a modular topology. By adjusting the number of sub-modules in series, the voltage and power level can be flexibly changed, and it can be extended to any level output, thereby reducing the The electromagnetic interference and the harmonic content of the output voltage are reduced, and the output voltage is very smooth and close to the ideal sinusoidal waveform, so there is no need for a large-capacity AC filter on the grid side. At the same time, because the modular topology disperses and stores energy in the capacitors of each sub-module of the bridge arm, it avoids the three-phase bridge arm coupling relationship of the two-level topology, thereby improving the fault ride-through capability. Based ...
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IPC IPC(8): H02M7/483H02M7/5387
Inventor 赵成勇张建坡赵鹏豪黄晓明陆翌裘鹏王朝亮周飞宗波
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)