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Pre-charging method for passive side power units of back-to-back half-bridge MMC circuit

A power unit and pre-charging technology, applied in electrical components, output power conversion devices, AC power input conversion to AC power output, etc., can solve complex problems, achieve small fluctuations in DC bus voltage, simple and reliable engineering implementation, The effect of small current shock

Active Publication Date: 2019-10-15
NARI TECH CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Although this method is feasible, it is not necessary to be so complicated for the startup process

Method used

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  • Pre-charging method for passive side power units of back-to-back half-bridge MMC circuit
  • Pre-charging method for passive side power units of back-to-back half-bridge MMC circuit
  • Pre-charging method for passive side power units of back-to-back half-bridge MMC circuit

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Embodiment Construction

[0025] The technical solutions of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0026] Such as figure 1 As shown, the back-to-back half-bridge MMC circuit includes active-side rectifier circuit, DC bus, passive-side inverter circuit and transformer T1 connected in sequence. The active-side rectifier circuit is connected to the grid side through the first charging resistor R1. A charging resistor R1 is connected to the circuit through the first charging resistor branch switch, and a first charging resistor bypass switch QF1 is provided in parallel. The DC bus is connected to the circuit through the first DC bus switch QL1 and the second DC bus switch QL2.

[0027] The primary side of the transformer is connected to the circuit through the transformer branch switch QF2, and the secondary side of the transformer is connected to the second charging resistor R2 and the third charging resistor R3. The second ...

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Abstract

The invention discloses a pre-charging method for passive side power units of a back-to-back half-bridge MMC circuit. The back-to-back half-bridge MMC circuit includes an active side rectifier circuit, a DC bus, a passive side inverter circuit and a transformer which are connected in sequence. The upper and lower bridge arms of the three phases of the active side rectifier circuit are N active side power units connected in series. The upper and lower bridge arms of the three phases of the passive side inverter circuit are N passive side power units connected in series. The power units are allhalf-bridge MMC circuits. The start pre-charging method of the invention does not need to collect the DC voltage value of each power unit and does not need a sorting algorithm. According to the method, the DC voltages of the passive side power units are improved mainly by rotation chopper control, and then, the fluctuation of the DC bus voltage is greatly reduced through voltage-current double-loop control adopted in the normal operation of the system. The method is simple and reliable, and is more applicable to engineering practice.

Description

technical field [0001] The invention belongs to the technical field of electric engineering, and mainly relates to a method for precharging a passive side power unit of a back-to-back half-bridge type MMC circuit. Background technique [0002] The back-to-back modular multilevel converter (MMC) has unique technical advantages such as simple structure, strong expandability, and no need for capacitor support on the DC bus, so it has been widely studied in the field of high-voltage and large-capacity power conversion. As the main optional structure of the MMC sub-module, the half-bridge topology is widely used in MMC-HVDC projects. [0003] The startup of the back-to-back half-bridge MMC is the first problem to be solved. At present, the precharging method is mainly divided into two types: self-excitation and external excitation. From an economical point of view, the cost of self-motivation is significantly lower than that of external excitation, so there are many ways to stu...

Claims

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Application Information

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IPC IPC(8): H02M7/483H02M7/5387H02M5/458
CPCH02M5/4585H02M7/483H02M7/53871
Inventor 隗华荣程谦梁帅奇董艳博牟晓春蒋真田安民侯凯王小红
Owner NARI TECH CO LTD