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Passive control method of MMC-SAPF based on condition of unbalanced grid voltage

A technology of MMC-SAPF and balance conditions, which is applied in the direction of reducing asymmetry of multi-phase network, eliminating/reducing asymmetry of multi-phase network, reactive power compensation, etc., to achieve ideal control effect and improve dynamic performance

Pending Publication Date: 2019-06-14
SHANGHAI UNIVERSITY OF ELECTRIC POWER
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  • Abstract
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  • Application Information

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Problems solved by technology

The nonlinear control of MMC-SAPF under unbalanced grid voltage is still in its infancy

Method used

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  • Passive control method of MMC-SAPF based on condition of unbalanced grid voltage
  • Passive control method of MMC-SAPF based on condition of unbalanced grid voltage
  • Passive control method of MMC-SAPF based on condition of unbalanced grid voltage

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Embodiment

[0055] Such as figure 1 The main circuit structure diagram of MMC-SAPF is shown. In the figure, the main circuit of SAPF is composed of MMC without components on the DC side. The parameters of each sub module (SM) are the same, and they all adopt a half-bridge structure. u sj (j=a,b,c) is the three-phase AC power supply voltage; i sj is the three-phase AC power supply current; i Lj is the three-phase load current; i fj Compensation current for three-phase SAPF; the load is composed of three-phase rectifier bridge and impedance R L , L L Composition; the impedance of the line connected to the load is R 1 , L 1 ; u cj is the three-phase AC voltage of the converter; R f , L f Respectively, the AC side resistance and inductance of the converter; L m is the bridge arm inductance. Each SM of the MMC is composed of an IGBT half-bridge and an energy storage and voltage stabilizing capacitor.

[0056] based on figure 2 The principle analysis and control process are descri...

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Abstract

The invention relates to a passive control method of MMC-SAPF based on condition of unbalanced grid voltage. The method comprises the steps: (1) adopting a positive and negative sequence separation dqcurrent detection method to flexibly select the current component to be compensated according to the capacity of APF; 2) according to the EL mathematical model under the condition of unbalanced gridvoltage of the MMC-SAPF, verifying the rigorous passivity; 3) adopting the energy storage function optimized by damping injection, designing a new passive controller which can completely decouple thecontrolled variables to the expected positive, wherein the positive and negative sequences of the controller are completely decoupled; 4) adopting APF circulating current suppression, average capacitor voltage control and capacitor voltage equalization control strategy, which are suitable for the condition of unbalanced power network voltage, to improve MMC-SAPF overall dynamic performance. The method provided by the invention is applicable to a three-wire system SAPF based on MMC under ideal and power network voltage unbalanced condition. Compared with the prior art, the present invention hasthe advantages of fast dynamic response and flexible compensation mode and is applicable to various unbalanced states of power network voltage.

Description

technical field [0001] The invention relates to the technical field of MMC-SAPF control, in particular to a passive control method based on MMC-SAPF under the condition of unbalanced grid voltage. Background technique [0002] With the access of a large number of power electronic devices, the nonlinear load in the distribution network increases, resulting in a decline in the power quality of the power grid. In addition, under the unbalanced state of the grid voltage such as voltage drop in the grid, unbalanced line parameters, and load asymmetry, the harmonics of the grid The power quality problem in this grid voltage unbalanced state needs to be solved urgently. [0003] The traditional two-level active power filter (APF) can only be applied to low-voltage distribution network due to the limitation of withstand voltage level. At present, the topologies of APFs used in medium-voltage distribution networks mainly include diode clamping type, flying capacitor type and H-bridg...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/01H02J3/18H02J3/26
CPCY02E40/30Y02E40/40Y02E40/50
Inventor 程启明王玉娇沈磊魏霖程尹曼
Owner SHANGHAI UNIVERSITY OF ELECTRIC POWER
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