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Modular multilevel bridge arm capacitor voltage balance control method based on AC side current compensation

A modular multi-level, capacitor voltage technology, applied in the direction of converting AC power input to DC power output, electrical components, output power conversion devices, etc.

Inactive Publication Date: 2016-07-06
哈尔滨同为电气股份有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0014] The present invention aims to solve the problem of difficult voltage balance control of bridge arm capacitors in existing converters. The present invention provides a modularized multi-level bridge arm capacitor voltage balance control method based on AC side current compensation

Method used

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  • Modular multilevel bridge arm capacitor voltage balance control method based on AC side current compensation
  • Modular multilevel bridge arm capacitor voltage balance control method based on AC side current compensation
  • Modular multilevel bridge arm capacitor voltage balance control method based on AC side current compensation

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specific Embodiment approach 1

[0041] Embodiment 1: The modularized multi-level bridge arm capacitor voltage balance control method based on AC side current compensation described in this embodiment includes the following steps:

[0042] Step 1: Obtain the given value Δi of the three-phase current offset on the AC side A , Δi B , Δi C ;

[0043] Step 2: Set the given value Δi of the AC side three-phase current offset obtained in Step 1 A , Δi B , Δi C , respectively superimposed on the expected value i of the three-phase current offset on the AC side * OA , i * OB , i * OC After , obtain the reference value i of the three-phase current on the AC side refA , i refB , i refC , the three-phase current reference value i on the AC side refA , i refB , i refC After three-phase to two-phase coordinate transformation, it is sent to the PI regulator,

[0044] At the same time, the actual value i of the three-phase current output by the converter is detected. OA , i OB , i OC , and after three-pha...

specific Embodiment approach 2

[0051] Specific implementation two: see figure 1 and 2 This embodiment is described. The difference between this embodiment and the modularized multi-level bridge arm capacitor voltage balance control method based on AC side current compensation described in Embodiment 1 is that the three-phase current on the AC side obtained in step 1 is different. Offset given value Δi A , Δi B , Δi C The process is,

[0052] Step 11: Detect the level voltages of n sub-modules of phase A, B, and C respectively, and obtain the capacitor voltage values ​​of the upper and lower bridge arms of n sub-modules of phase A, and the capacitor voltage values ​​of upper and lower bridge arms of n sub-modules of phase B and The capacitor voltage values ​​of the upper and lower bridge arms of the n sub-modules of phase C,

[0053] Step 1 and 2: Calculate the average value of the upper and lower bridge arm capacitor voltages of each phase, and filter out high-frequency fluctuation components through ...

specific Embodiment approach 3

[0056] Specific implementation mode three: see image 3 This embodiment is described. The difference between this embodiment and the modularized multi-level bridge arm capacitor-voltage balance control method based on AC side current compensation described in Embodiment 1 or 2 is that the method described in Step 4 is obtained according to Step 1. The given value Δi of the three-phase current offset of the AC side A , Δi B , Δi C and the reference value i of the three-phase current on the AC side obtained in step 2 refA , i refB , i refC , get the zero-sequence voltage u 0 The process is,

[0057] Through the given value Δi of the three-phase current offset on the AC side A , Δi B , Δi C and the reference value i of the three-phase current on the AC side obtained in step 2 refA , i refB , i refC , to obtain the zero-sequence component of the feedback current (Δi A +Δi B +Δi C ) / 3 and the reference current zero sequence component (i refA +i refB +i refC ) / 3, ...

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Abstract

The invention provides a modularized multilevel bridge arm capacitor voltage balance control method based on AC side current compensation, which belongs to the field of bridge arm capacitor voltage balance control of converters. In order to solve the problem of difficult voltage balance control of the bridge arm capacitance of the existing converter. By closed-looping the capacitor voltage error of the upper and lower bridge arms of each phase of the converter, the result is used to adjust the AC side current setting, control the compensated current reference, and use the offset of the AC side current to suppress the upper and lower bridge arm capacitances Voltage imbalance. Count the capacitor voltages of the upper and lower bridge arms of each phase, perform PI control on the voltage difference of the bridge arm capacitors of each phase, superimpose the output of the PI regulator on the original AC side current set value, and decouple the new current set value, and finally Realize bridge arm capacitor voltage balance. The invention is applicable to various application occasions of modularized multilevel converters.

Description

technical field [0001] The invention belongs to the field of bridge arm capacitor voltage balance control of converters. Background technique [0002] The modular multi-level converter can achieve high voltage output by superimposing the output voltage of the sub-modules. At the same time, its DC side is connected in parallel to realize energy exchange, which is especially suitable for the field of high voltage direct current transmission (HVDC), and it is also used in medium voltage inverter control and medium voltage SVG. One of the control problems in this method is its capacitor-voltage balance control. Its capacitor voltage balance control includes phase-to-phase, bridge-arm and bridge-arm balance control. [0003] For the phase-to-phase capacitor voltage balance control, the power can be controlled from the DC side or the AC side; for the capacitor voltage balance in the bridge arm, it can be solved by sorting, superimposing voltage and other methods. However, for t...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/483
Inventor 杨荣峰杨旭刘宇光何崇飞
Owner 哈尔滨同为电气股份有限公司