Design method of unit number for cascaded h-bridge converter withstanding asymmetrical voltage sag
A voltage sag and design method technology, applied in the direction of electrical components, AC power input conversion to DC power output, output power conversion devices, etc., can solve the problem of affecting power electronic equipment, ignoring the ability of power electronic equipment to withstand sag Increase the cost of voltage sag treatment and other issues to achieve the effect of improving operational reliability and reducing system costs
Active Publication Date: 2020-05-12
STATE GRID HUBEI ELECTRIC POWER RES INST +2
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Problems solved by technology
However, there are power quality problems such as voltage sag in the power grid, which will affect the normal operation of power electronic equipment, so the cascaded H-bridge converter as one of the power electronic equipment will be affected by voltage sag
[0003] In order to protect power electronic equipment from the influence of voltage sag, current research mainly focuses on how to design voltage sag compensation devices such as SVC, D-STATCOM, DVR, UPQC, etc., but ignores the ability of power electronic equipment to withstand sag , increasing the cost of voltage sag control
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[0023] The technical solutions in the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the present invention.
[0024] figure 1 It is the topological structure of the cascaded H-bridge converter in the embodiment of the present invention, including a multi-winding phase-shifting transformer and a plurality of power units. The power cell topology is as figure 2 As shown, including three-phase uncontrolled rectifiers (D1-D6) and H-bridge inverters (Q1-Q4). The output voltage of the multi-winding phase-shifting transformer passes through the three-phase uncontrolled rectification circuit in each power unit, and is used as the DC power supply of the H-bridge inverter of each power unit. After each power unit is connected in series to form a bridge arm, PS modulation is used to supply power to the load.
[0025] The method for designing the cascaded number of cascaded H-bridge converters to withstand asymmetric vol...
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The invention provides a method for designing the number of units of a cascaded H-bridge converter resisting asymmetric voltage sag. The method comprises the following steps: firstly, obtaining an average voltage expression of the DC side of each power unit under asymmetric voltage sag according to the non-control rectifier bridge arm conduction characteristics of each power unit under asymmetricvoltage sag; and determining the number of cascade units required by the cascaded H-bridge converter resisting asymmetric voltage sag according to an output rated voltage of the cascaded H-bridge converter, a DC voltage and a modulation ratio constraint condition by using the average voltage expression of the DC side. The method starts from the improvement of the voltage sag tolerance capability of the cascaded H-bridge converter, so that the cascaded H-bridge converter has the immune asymmetric voltage sag capability, the voltage sag treatment cost is greatly reduced, and the method is easy to implement.
Description
technical field [0001] The invention relates to the technical field of power electronics, in particular to a method for designing the number of units of a cascaded H-bridge converter capable of withstanding asymmetrical voltage sags. Background technique [0002] Cascaded H-bridge converters have been widely used in many fields in recent decades due to their significant advantages such as high voltage level, high power level, high waveform quality and high modularity. In the past few decades, the research related to the cascaded H-bridge converter mainly focused on the internal power balance and energy exchange of the cascaded H-bridge converter and the modulation method and control strategy of the cascaded H-bridge converter. The research is generally based on the premise that the grid voltage is ideal, which simplifies the research difficulty of the cascaded H-bridge converter. However, there are power quality problems such as voltage sags in the power grid, which will af...
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IPC IPC(8): H02M7/5387
CPCH02M7/5387
Inventor 胡伟李小平吴耀文沈煜杨帆杨志淳
Owner STATE GRID HUBEI ELECTRIC POWER RES INST