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Over-voltage protection method and device of modular multilevel converter

A modular multi-level, inverter technology, applied in the direction of emergency protection circuit devices, electrical components, etc., can solve the problems of sub-module bypass, sub-module bypass, bipolar short circuit, etc., to achieve accurate action, avoid Vicious circle, the effect of ensuring stable and safe operation

Active Publication Date: 2016-06-15
NR ELECTRIC CO LTD +1
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Problems solved by technology

[0004] When the flexible DC transmission equipment is in normal operation, the capacitor voltages of all sub-modules of a valve arm are basically the same. When a sub-module judges its own overvoltage and bypasses, the voltage it bears will be shared on other sub-modules of the valve arm. It may cause more sub-modules to be bypassed, thus falling into a vicious circle of sub-modules bypassing one by one, and even lead to a double-pole short circuit

Method used

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  • Over-voltage protection method and device of modular multilevel converter
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  • Over-voltage protection method and device of modular multilevel converter

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Embodiment Construction

[0027] The technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0028] The overvoltage protection method of the modularized multi-level converter provided by the present invention judges that the voltage of the entire valve arm is detected by detecting the voltage of a single sub-module of the converter, the voltage of the valve arm to which the sub-module belongs and the average capacitance voltage of the valve arm sub-module. Whether the systemic overvoltage or a single submodule overvoltage determines how the overvoltage protection of the modular multilevel converter operates.

[0029] According to the method described in claim 1 in the present invention, to figure 1 The overvoltage protection of the modular multilevel converter shown is described as figure 2 Shown:

[0030] (1) Detect the voltage of a single sub-module as v m , the voltage sum of the valve arm to which t...

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Abstract

The invention provides an over-voltage protection method and device of a modular multilevel converter. Whether the whole valve arm encounters a systemic over-voltage situation or a single submodule encounters an over-voltage situation is judged by detecting the voltage of the single submodule of the converter and the voltage of the valve arm to which the submodule belongs and / or the average capacitor voltage of the submodule of the valve arm, rapid and accurate action of over-voltage protection of the converter is ensured, vicious circulation of sequent bypasses of the submodule is prevented, and the stable and safe running of a flexible DC power transmission system is ensured.

Description

technical field [0001] The invention relates to the technical field of flexible DC power transmission in electric power systems, in particular to an overvoltage protection method for a modular multilevel converter and a corresponding protection device. Background technique [0002] Flexible DC transmission uses a voltage source converter, which can independently and quickly control the active power and reactive power of the system, thereby improving system stability, suppressing system frequency and voltage fluctuations, and improving the steady-state performance of the grid-connected AC system. [0003] For the flexible DC transmission project in actual operation, overvoltage is a major threat to the converter valve, and the overvoltage capability of the shut-off devices and capacitors of the valve group is limited. Overvoltages in the order of microseconds can cause damage to devices that can be turned off. The overvoltage protection function of the converter valve includ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02H7/122
Inventor 汪涛王柯冯亚东董云龙田杰李海英卢宇
Owner NR ELECTRIC CO LTD
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