A DC Voltage Compensation Method for Parallel Hybrid Multilevel Converter
A multi-level converter and DC voltage technology, applied in the field of DC voltage compensation, can solve problems such as failure to operate normally, DC voltage drop, and no DC voltage compensation mechanism, so as to achieve system AC fault ride-through and solve DC Effects of Voltage Fluctuation Problems
Active Publication Date: 2018-05-08
STATE GRID CORP OF CHINA +2
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[0007] However, the AC-DC side voltage of the new topology is seriously coupled, which causes the DC voltage of the flexible DC system to change with different working conditions, especially when the AC system fails, the DC voltage of the converter drops sharply , can not operate normally, which is contrary to the operation requirements of the flexible DC system, that is, the stable DC voltage and the AC fault ride-through capability
[0008] US2012 / 0069610 A1 discloses this topology, but does not give the corresponding DC voltage compensation mechanism. In the article "A Low Loss Modular Multilevel Voltage Source Converter for HVDCPower Transmission and Reactive Power Compensation", a third harmonic based The voltage compensation method of wave voltage injection, but this method cannot be used for system faults, especially the voltage sag under asymmetrical faults
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[0027] The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.
[0028] The invention provides a DC voltage compensation method for a parallel hybrid multi-level converter. The converter has a three-phase power transmission structure, and the three-phase power transmission structure is composed of a parallel-connected single-phase structure in series; a parallel-connected type The single-phase structure is composed of a parallel H-bridge fully-controlled device structure and a sub-module cascaded structure. The H-bridge fully-controlled device structure is composed of four fully-controlled devices. The sub-modules are connected in series. The specific implementation of the method is as follows:
[0029] Such as image 3 As shown, in the normal operation mode, when S1 and S4 are turned on, the output voltage of module 1 is led to the AC side, forming an AC positive half wave; when S2...
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A direct current voltage compensation method for a parallel mixed-type multi-level converter. The converter is a three-phase power transmission structure, the three-phase power transmission structure consisting of a parallel-type single-phase structure series connection. A parallel-type single-phase structure consists of an H bridge full-control device structure (2) and a sub-module cascade structure (1) connected in parallel, the H bridge full-control device structure consisting of a cascade structure having four full-control devices (S1-S4), the sub-module cascade structure consisting of a half-bridge sub-module series connection. The compensation method comprises: an isolation time is added during a converter normal operating mode, the sub-module cascade structures are freely controlled in the isolation time, a required compensation voltage is thereby outputted, compensation of a direct current voltage shortfall is implemented, and a compensation ratio in the three-phase power transmission structure adjusts a three-phase distribution ratio according to requirements. The compensation method effectively implements direct voltage fluctuation compensation of a parallel-type mixed new topology, and is particularly suitable for voltage compensation in the case of an alternating current system fault.
Description
technical field [0001] The invention relates to a direct current voltage compensation method, in particular to a direct current voltage compensation method for a parallel hybrid multilevel converter. Background technique [0002] The flexible direct current transmission system is a direct current transmission system based on a voltage source converter with a fully controlled device (IGBT) as the core. It has broad applications in many fields such as wind power access, grid interconnection, urban power supply, and island power supply. Foreground, since the development of flexible DC technology, it has experienced two main technical routes, namely two-level technology and modular multi-level technology, the latter has low switching frequency and low loss, and has become the main development of flexible DC transmission technology trend. [0003] The converter of the flexible DC transmission system is the core component of the whole system, used to realize the conversion of AC ...
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IPC IPC(8): H02M7/17H02J3/36
CPCH02M7/17Y02E60/60
Inventor 杨杰贺之渊李强马巍巍周扬
Owner STATE GRID CORP OF CHINA