A method and device for controlling the voltage of a sub-module of a flexible DC converter valve
A sub-module voltage and flexible DC technology, which is applied in the direction of output power conversion device, AC power input conversion to DC power output, electrical components, etc., can solve sub-module overvoltage tripping, no consideration of voltage equalization and inconsistent charging characteristics, very different issues
Active Publication Date: 2021-02-09
NR ELECTRIC CO LTD +1
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[0006] The patent "201410768743.3" proposes "a sub-module distributed control method", aiming at the deficiency of the patent "CN201210451946", it proposes to calculate the number of input sub-modules according to the dynamic change of the number of normal sub-modules and a weight method, which is only applicable to Based on a single type of sub-module grouping, it does not consider the inconsistency of voltage equalization and charging characteristics after multiple types of sub-modules are grouped
When the current changes sharply, the voltage between different types of sub-modules will vary greatly, and even cause the sub-modules to trip due to overvoltage, affecting the stability of the system operation
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[0058] The technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings and specific embodiments.
[0059] A flexible DC converter valve sub-module voltage control method, such as figure 1 As shown, the different types of sub-modules of each bridge arm of the converter valve are divided into M groups, M is a natural number, M≥1, and the number of sub-modules in each group is is a natural number, i is the group number and 1≤i≤M, each group corresponds to a valve control device, each valve control device operates independently, the upper controller sends the number of sub-module inputs to the valve control device, and the number of sub-module inputs is calculated Proceed as follows
[0060] (1) The upper controller calculates the total number of sub-modules that should be put into the corresponding bridge arm where v ref is the real-time reference wave, U CN is the voltage rating of a single sub-module;
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The present invention provides a flexible DC converter valve sub-module voltage control method and device. By grouping different types of sub-modules of each bridge arm of the flexible DC converter valve, each group corresponds to a valve control device. The upper control device calculates the number of sub-modules put into operation in each group according to the weight of each group, and then dynamically adjusts the previously calculated weights according to the deviation degree of each sub-module group voltage relative to the rated voltage of the sub-module, and finally combines the corresponding The maximum number of normal sub-modules that can be put into operation on the bridge arm calculates the number of sub-modules that are finally put into operation in each group, and sends it to the valve control device, so as to solve the problem that the voltage of the grouped sub-modules in the dynamic process of the flexible direct current transmission system is affected by the weight of the number of inputs. In the case of sub-module overvoltage or undervoltage caused by too slow, the valve control device works according to the pressure equalization strategy and gating method provided by the existing literature.
Description
technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a voltage control method and device for a sub-module of a flexible DC converter valve. Background technique [0002] With the development of power electronics technology, flexible DC transmission technology based on modular multilevel converters has been extensively researched and applied. The bridge arm of this type of topology adopts the form of cascading basic operating units, avoiding the direct series connection of a large number of switching devices, and there is no problem such as drive consistency, which greatly reduces the technical barriers of DC power transmission. For a large number of sub-module units connected in series, it is necessary to carry out voltage equalization control. [0003] At present, the sub-module voltage equalization strategy usually adopts the method of sub-module capacitor voltage sorting, but when the number of bridge arm ...
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IPC IPC(8): H02M7/00H02J3/36
CPCY02E60/60
Inventor 王柯鲁江卢宇董云龙丁久东汪楠楠李钢胡兆庆邱德锋
Owner NR ELECTRIC CO LTD