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High-capacity unified power quality conditioner based on chain structure and control method thereof

A technology of power quality and control method, applied in the direction of AC network voltage adjustment, reactive power compensation, multi-phase network asymmetry reduction, etc., can solve the problems of capacitor voltage imbalance, high requirements, small UPQC capacity, etc.

Inactive Publication Date: 2014-02-26
STATE GRID CORP OF CHINA +2
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  • Abstract
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  • Application Information

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Problems solved by technology

[0004] The UPQC capacity of the three-phase three-wire structure is small, which does not meet the large-capacity compensation needs of industrial users
And because the three-phase output voltages of the three-phase bridge are related to each other, the control is more complicated, and the zero-sequence voltage cannot be provided to the system; while the three-phase four-wire structure can compensate the zero-sequence, but it has high requirements for the output voltage of the DC side, and the switching device The withstand voltage value is high, and the capacitor voltage on the DC side is prone to imbalance

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  • High-capacity unified power quality conditioner based on chain structure and control method thereof
  • High-capacity unified power quality conditioner based on chain structure and control method thereof
  • High-capacity unified power quality conditioner based on chain structure and control method thereof

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Embodiment Construction

[0030] The specific implementation manners of the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0031] The chain structure-based large-capacity three-phase three-wire system serial-parallel structure UPQC main loop topology proposed by the present invention is as follows: figure 2As shown, it includes series-connected voltage source converters and parallel-connected voltage source converters connected through the common DC bus. The capacitor is connected to the grid on the AC side (system side or power supply side). The parallel voltage source converter is a single-phase H-bridge structure, which forms a "back-to-back" structure with the H-bridge links on the series side. Each H-bridge link of the parallel voltage source converter is connected to the secondary side of the single-phase multi-winding transformer. On the load side (load side or DC side). The parallel voltage source converter plays the role of volta...

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Abstract

The invention relates to a high-capacity unified power quality conditioner based on a chain structure and a control method of the high-capacity unified power quality conditioner. A three-phase three-wire system series-and-parallel structure is adopted in the high-capacity unified power quality conditioner. The high-capacity unified power quality conditioner comprises a series type voltage source converter and a parallel type voltage source converter, wherein the series type voltage source converter and the parallel type voltage source converter are connected through a common direct-current bus, single-phase H-bridge cascade structures are adopted in the series type voltage source converter, the H-bridge cascade structure of each phase is connected to an alternating-current side power grid through a series capacitor, single-phase H-bridge chain link structures are adopted in the parallel side converter, a back-to-back structure is formed by the single-phase H-bridge chain link structures and H-bridge chain links of the series type voltage source converter, and each H-bridge chain link of the parallel side converter is connected to a direct-current side power grid through the secondary side of a single-phase multi-winding transformer. The invention further provides the control method of the high-capacity unified power quality conditioner. According to the high-capacity unified power quality conditioner, a series side transformer is omitted, short-circuit impedance of a loop is reduced, voltage accuracy of open-loop control is improved, performance of the high-capacity unified power quality conditioner is improved, and the problem that the instantaneous inrush current phenomenon happens when voltage drop of the series side happens is solved.

Description

technical field [0001] The invention relates to a unified power quality controller (UPQC-Unified Power Quality Conditioner) and a control method thereof, in particular to a large-capacity unified power quality conditioner based on a chain structure and a control method thereof. Background technique [0002] The unified power quality controller (UPQC-Unified Power Quality Conditioner) is composed of a series voltage source converter and a parallel voltage source converter through a common DC bus. It is applied to the power distribution system and connected near the harmonic load. Both voltage and current can be compensated simultaneously. The series converter plays the role of a dynamic voltage compensator (DVR-Dynamic Voltage Restorer), which can suppress voltage fluctuations, compensate power supply voltage harmonics, eliminate voltage swells and voltage temporary problems that often occur in power distribution systems, and improve System damping. The parallel-connected c...

Claims

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Application Information

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IPC IPC(8): H02J3/12H02J3/26H02J3/18
CPCY02E40/50Y02E40/30
Inventor 夏冰燕翚叶卫华袁蒙
Owner STATE GRID CORP OF CHINA
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