Inverter, DC side grounded three-level structure flexible DC system and control method

A flexible DC, three-level structure technology, applied in the direction of conversion of AC power input to DC power output, power transmission AC network, output power conversion device, etc., can solve the problem of insufficient DC grid fault ride-through capability, power supply continuity and reliability Unable to achieve and other problems, to achieve the effect of alleviating the lack of transmission capacity, rapid transfer, and increasing transmission capacity

Active Publication Date: 2020-06-09
WUHAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Limited by the current DC fault current limiting and breaking technology, the fault ride-through capability of the DC grid is insufficient, and the continuity and reliability of its power supply cannot reach the level of the traditional AC grid

Method used

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  • Inverter, DC side grounded three-level structure flexible DC system and control method
  • Inverter, DC side grounded three-level structure flexible DC system and control method
  • Inverter, DC side grounded three-level structure flexible DC system and control method

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Embodiment Construction

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

[0028] Such as figure 1 The shown converter can be applied in the DC side grounded three-pole structure flexible DC system. The three DC poles of the converter include positive pole, negative pole and the third pole, and each DC pole includes a modular multi-level converter (MMC) and a smoothing reactor (L dc ). Among them, the modular multilevel converter is used as an AC / DC converter, and the AC side is connected to the three-phase power supply v of the converter transformer an , v bn and v cn (n=1,2,3), one end of the DC side (first terminal) passes through the smoothing reactor L dc Finally, it is connected to the DC line as a DC pole, and the other end (the second terminal) is directly grounded or grounded through a resistor. That is: one end of three modular multilevel converters (positive MMC, negative MMC and third pole ...

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Abstract

The invention discloses a converter, a DC-side grounded three-stage flexible DC system and a control method. The DC electrodes of the converter include a positive pole, a negative pole and a third pole, wherein each DC electrode includes a smoothing reactor and has a A modular level shifter capable of bidirectional operation of DC voltage and DC current. The modular level shifter includes an AC side and a DC side. The AC side is used to connect to the three-phase power supply of the converter transformer. The DC side includes the first terminal and the second terminal. Two terminals, the first terminal is connected to the DC line as a DC electrode after passing through the smoothing reactor, and the second terminal is grounded. The flexible DC system with the converter has a normal bipolar operation mode, a single-stage operation mode, two unipolar parallel operation modes and a capacity-increasing operation mode. Through the control of the fault pole voltage and the flexible switching of the operation mode, the rapid transfer of fault transient energy on the DC side can be realized, the DC fault current can be effectively suppressed, and the stability and continuity of power transmission during the fault period can be ensured.

Description

technical field [0001] The invention belongs to the field of direct current transmission and distribution of power systems, and in particular relates to a converter, a direct current side grounding three-stage flexible direct current system and a control method. Background technique [0002] In the field of power system transmission and distribution, with the increasing scale of photovoltaic, wind power and other new energy grid connection and energy storage access, as well as intermittent loads such as electric vehicles, it is necessary to adopt a flexible way to connect to the traditional AC transmission and distribution network . The high-voltage direct current transmission and distribution technology based on the voltage source converter (Voltage Source Converter, VSC) has active power and reactive power that can be independently and flexibly controlled, and can supply power to passive systems, with good waveform quality and voltage polarity when the power flow is revers...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/219H02M1/32H02J3/36
CPCH02J3/36H02M1/32H02M7/219H02M1/325Y02E60/60
Inventor 王朋
Owner WUHAN UNIV
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