MMC DC voltage outer loop controller and generation method thereof

A DC voltage, DC side voltage technology, applied in the direction of AC power input conversion to DC power output, electrical components, power transmission AC network, etc., can solve the problems of limited application scope, low accuracy, low universality, etc. High model accuracy, high precision effects

Active Publication Date: 2017-12-08
HUAZHONG UNIV OF SCI & TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] In view of the above defects or improvement needs of the prior art, the object of the present invention is to provide a MMC DC voltage outer loop controller and a generation method, thereby solving the problem of the low accuracy of the existing DC voltage outer loop controller generation method , low universality and limited application range technical problems

Method used

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  • MMC DC voltage outer loop controller and generation method thereof
  • MMC DC voltage outer loop controller and generation method thereof
  • MMC DC voltage outer loop controller and generation method thereof

Examples

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Embodiment 1

[0117] The load connected to the converter is a rated resistance R L , its resistance is 400Ω, such as Figure 4 As shown, the system has no negative level output, that is, the maximum modulation ratio of the system is 1, and the output voltage of the bridge arm is always greater than 0, such as Figure 5 shown. For the case with a constant power resistive load, the exact DC voltage u dc and active current i d The transfer function between them is:

[0118]

[0119] Among them, Δu dc is the disturbance of DC side voltage, Δi d is the disturbance of the d-axis component of the AC side current (i.e. the active current), u c_1d0 is the steady-state quantity of the d-axis component of the fundamental frequency component of the sub-module capacitor voltage, u c_1q0 is the steady-state quantity of the q-axis component of the fundamental frequency component of the sub-module capacitor voltage, u dc0 is the steady-state quantity of DC side voltage, R L is the load resistan...

Embodiment 2

[0128] The load connected to the converter is a rated resistance R L , the resistance value is 400Ω, the system has a negative level output, and the maximum modulation ratio of the system is set to 2, the output voltage of the bridge arm will have a negative value, such as Figure 8 shown. For the case with rated resistive load, the DC voltage u dc and active current i d The simplified transfer function between is:

[0129]

[0130] Among them, Δu dc is the disturbance of DC side voltage, Δi d is the disturbance of the d-axis component of the AC side current (i.e. the active current), u dc0 is the steady-state quantity of DC side voltage, u cd0 is the steady-state quantity of the d-axis component of the PCC point voltage, R L is the load resistance, C is the capacitance value of the sub-module, N is the number of sub-modules of each bridge arm, m max is the maximum modulation ratio allowed by the system, and s is the Laplacian operator.

[0131] In the traditional ...

Embodiment 3

[0136] Set the load connected to the converter controlled by constant DC voltage as a converter station controlled by constant power, such as Figure 10 shown. For the case of a converter station with constant power control, the DC voltage u dc and active current i d The simplified transfer function between is:

[0137]

[0138] Among them, Δu dc is the disturbance of the DC side voltage of the converter station controlled by a constant DC voltage, Δi d is the disturbance of the d-axis component (i.e. active current) of the AC side current of the converter station controlled by a constant DC voltage, u dc0 is the steady-state quantity of the DC side voltage of the converter station controlled by the constant DC voltage, u cd0 is the steady-state quantity of the d-axis component of the PCC point voltage of the converter station controlled by constant DC voltage, C is the sub-module capacitance value of the converter station controlled by constant DC voltage, and C' is t...

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Abstract

The invention discloses an MMC DC voltage outer loop controller and a generation method thereof. According to the generation method of the controller, the influence of the submodule capacitance voltage dynamics of a modular multilevel converter and the load dynamics on the DC voltage dynamics is considered, a DC side small signal mathematical model is established, a transfer function between the DC side voltage and the active current is derived, and a target DC voltage closed-loop control model is obtained according to the transfer function so that the target DC voltage outer loop controller is obtained from the target DC voltage closed-loop control model. The DC side equivalent capacitance is derived from the angle of the circuit so as to have higher accuracy in comparison with the conventional equivalent lumped capacitance obtained by the energy equivalence principle; meanwhile, different operation state of the converter topology is considered so that the universality is high; besides, the influence of the DC side dynamic behaviors on the controller is considered, including two situations that the DC side is the constant power resistance load and the converter station load so that the range of application is wide.

Description

technical field [0001] The invention belongs to the technical field of multilevel power electronic converters, and more specifically relates to an MMC DC voltage outer loop controller and a generating method. Background technique [0002] The Modular Multilevel Converter (MMC) has the advantages of good output waveform quality, no dynamic and static voltage equalization problems of switching devices, easy expansion, and high system efficiency, and has become the most competitive converter in the flexible DC transmission system. streamer topology. [0003] Vector control is a control method commonly used in MMC converters. Establishing an accurate mathematical model and deriving the inner and outer loop transfer functions are the prerequisites for controller design. At present, most of the modeling of MMC is concentrated on the AC side (that is, the current inner loop), while the precise modeling of the DC voltage outer loop is less, and more specifically, the transfer funct...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/483H02J3/36
CPCY02E60/60H02M7/483H02J3/36
Inventor 胡家兵万敏何震林磊
Owner HUAZHONG UNIV OF SCI & TECH
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