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C-MMC multivariable protection control method under three-phase power grid imbalance

A three-phase power grid, protection and control technology, applied in the direction of reducing the asymmetry of the polyphase network, eliminating/reducing the asymmetry of the polyphase network, power transmission AC network, etc. Adjust and control, reduce amplitude, eliminate the effect of double frequency oscillation

Inactive Publication Date: 2018-03-13
HANGZHOU DIANZI UNIV
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  • Description
  • Claims
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Problems solved by technology

However, at present, flexible positive sequence and negative sequence control are mainly used in new energy power generation, and there is a lack of analysis and description of system operating performance

Method used

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  • C-MMC multivariable protection control method under three-phase power grid imbalance
  • C-MMC multivariable protection control method under three-phase power grid imbalance
  • C-MMC multivariable protection control method under three-phase power grid imbalance

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Embodiment Construction

[0026] The present invention will be further described below in conjunction with the accompanying drawings of the specification.

[0027] The topological structure diagram of the modular multilevel converter (C-MMC) with clamped dual sub-modules is as follows figure 1 As shown, the sub-module topology diagram is as figure 2 Shown. When an unbalanced fault occurs in the AC voltage on the grid side, the three-phase current will be unbalanced and there will be large voltage ripples and power fluctuations on the DC side, which may endanger the safety of the converter in severe cases. The C-MMC multivariable protection control method under the unbalanced three-phase power grid proposed by the present invention can effectively avoid the problem. The system control block diagram of the method proposed by the present invention is as follows image 3 Shown. The main steps of the method are as follows:

[0028] (1) Initialize system variables, set all current and voltage related parameter...

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Abstract

The present invention discloses a C-MMC multivariable protection control method under three-phase power grid imbalance. A three-phase current of a system is unbalance and a direct current side has a large voltage ripple and power fluctuation when an alternating-current power grid has faults, and in a severe case, the safety of a convertor is threatened and the life of the convertor is shortened, so influences of power grid negative sequence components on the system must be reasonably controlled. The C-MMC multivariable protection control method under three-phase power grid imbalance employs the improved a flexible positive and negative sequence control algorithm (FPNSC) and employs a flexible positive and negative sequence control strategy in a d-q coordinate system to perform regulation of parametric variables and reasonably regulate positive and negative content of grid current reference to reasonably control the grid current waveform quality and instant active power and inactive power of the system, and therefore, the protection and control of the C-MMC are achieved.

Description

Technical field [0001] The invention belongs to the field of power electronic power converters, and particularly relates to a C-MMC multivariable protection control method under unbalanced three-phase power grids. Background technique [0002] The application of flexible direct current transmission has expanded the application of power electronic converter technology in the field of power system transmission. C-MMC is considered to be a topology circuit with more application prospects due to its better ductility. It is widely used in flexible direct current transmission (VSC). -HVDC) field, especially in the field of multi-terminal flexible DC transmission that has emerged in recent years. [0003] In AC / DC hybrid power transmission and distribution, the existence of negative sequence components of the power grid will cause the three-phase current of the system to be unbalanced or non-sinusoidal, and large voltage ripples and power fluctuations on the DC side will endanger the conv...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/36H02J3/26H02J3/24
CPCH02J3/24H02J3/26H02J3/36H02J2003/365Y02E40/50Y02E60/60
Inventor 杭丽君邱键何远彬朱明琳王文杰
Owner HANGZHOU DIANZI UNIV
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