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A Universal Sequence Impedance Model and Modeling Method for Grid-connected Converter Used in Stability Analysis

A technology of impedance model and modeling method, which is applied in the field of grid-connected stability analysis of power devices, can solve the problems of convenience discount, limited application promotion, complex impedance model establishment, etc., and achieves the effect of wide application range and flexible use

Active Publication Date: 2022-01-18
JINAN UNIVERSITY
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0006] 2. So far, the converter impedance model is derived based on the assumption of a specific control design, so this model and related derivations are only applicable to converters with this specific control structure
The limitations of these models hinder the general solution and research development of power system stability analysis, and thus limit its application and promotion
In the grid-connected system of converters, the frequency conversion of disturbance signals and the coupling between multi-phase, multi-sequence and AC-DC networks make the establishment of impedance models more complicated
So far, only the converter impedance model for a specific control structure has been applied, which makes the stability and related analysis time-consuming and laborious.
Its ease of use is greatly reduced
[0007] 3. The above-mentioned DQ impedance and sequence impedance models do not consider the coupling between DC and AC circuits in depth. Although the literature [14]-[15] discusses the modeling of DC side impedance, it ignores the dynamic response of the AC system, and Literature [16] also introduced the influence of DC voltage control on system stability, and recent literature [17]-[18] discussed the phenomenon of AC-DC circuit coupling through voltage source converter

Method used

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  • A Universal Sequence Impedance Model and Modeling Method for Grid-connected Converter Used in Stability Analysis

Examples

Experimental program
Comparison scheme
Effect test

) example 1

[0149] 1) Case 1: AC current control

[0150] like Figure 4 The AC current control structure is shown, so the transfer function of the control loop is obtained as

[0151]

[0152] Among them, H i (s) is the current controller transfer function, and Represents the converter operating condition.

[0153] Then according to the formula formula and the transfer function of the control loop to obtain Substituting the transfer function of the control loop into each element in the matrix element formula of the AC side small-signal admittance model of the converter, we can obtain

[0154] If AC voltage feed-forward is not used, T in the formula v (s) and T vn (s) is replaced by 0, and the elements of the admittance matrix are obtained as follows:

[0155] where Y dp (s+jω 1 ) and Y dn (s-jω 1 )constant.

) example 2

[0156] 2) Case 2: DC voltage control

[0157] like Figure 5 The DC voltage control structure is shown, so the transfer function of the control loop is obtained as

[0158] Considering the power balance between the input and output of the converter, from the formula formula and the transfer function of this control loop can be obtained

[0159] Substituting the transfer function of the control loop into each element in the matrix element formula of the small-signal admittance model of the AC side of the converter, we can obtain

[0160]

[0161] In addition Y pp (s+jω 1 ), Y np (s+jω 1 ), Y nn (s-jω 1 ) and Y pn (s-jω 1 ) is consistent with Case 1, literature [17] gives the impedance modeling in the case of no AC voltage feed-forward, and the final formula obtained in Case 1 and Case 2 (ie: substituting the transfer function of the control loop into Each element in the matrix element formula of the AC side small-signal admittance model of the converter, th...

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Abstract

The invention relates to a converter grid-connected general sequence impedance model and a modeling method for stability analysis. The converter grid-connected general sequence impedance model includes a small-signal converter sequence impedance model and a converter parallel The network sequence impedance model, the converter sequence impedance model includes the AC side admittance and the DC side admittance model, and the corresponding converter grid-connected sequence impedance model includes the AC side lumped admittance model and the DC side of the converter grid-connected Lumped Admittance Model. The circuit stability of the AC and DC sides can be analyzed based on the general sequence impedance model of the converter grid. The derived general sequence impedance model is suitable for various converters based on the DQ coordinate transformation control structure. This model can be used very conveniently The grid-connected sequence impedance of any converter with a specific control structure can be obtained accurately, and the application range is extremely wide, and the use is flexible and convenient. In addition, the modeling method of the present invention can be used for derivation of a general model of converter grid connection based on other coordinate structures.

Description

technical field [0001] The invention belongs to the technical field of grid-connected stability analysis of power devices, and in particular relates to a converter grid-connected general sequence impedance model and a modeling method for stability analysis. Background technique [0002] Converters are widely used in distributed energy, electric traction, high-voltage direct current transmission, flexible alternating current transmission systems and other fields, and with the application of renewable energy and the development of modern power systems, their applications are becoming more and more extensive. The converter is usually used as an intermediate unit between the AC circuit and the DC circuit, which plays an important role in the interconnection expansion characteristics and stability of the power system (see literature [1]-[6]). [0003] So far, engineering technicians and related researchers usually study the impedance characteristics of the converter on the basis ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02J3/38
CPCH02J3/38
Inventor 郭焕刘敏
Owner JINAN UNIVERSITY