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A converter output impedance shaping method and system

A technology of output impedance and converter, which is applied in the field of converter output impedance shaping method and system, can solve the difficult frequency characteristics of the converter, does not consider the complex coupling relationship of multi-machine interactive system, and cannot effectively realize the impedance optimization of multi-machine interactive system and other issues to achieve the effect of improving the stability margin and preventing system oscillation

Active Publication Date: 2021-05-14
NANJING UNIV OF AERONAUTICS & ASTRONAUTICS
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, in fact, the control loops of the converter are not completely decoupled, and there are several control loops that jointly affect the frequency characteristics of the converter in a certain frequency range. It is difficult to ensure that the converter has the best frequency characteristics when plasticizing
In addition, since the complex coupling relationship between multi-machine interactive systems is not considered, this method cannot effectively realize the impedance optimization of multi-machine interactive systems and maximize the stability of the system

Method used

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  • A converter output impedance shaping method and system
  • A converter output impedance shaping method and system
  • A converter output impedance shaping method and system

Examples

Experimental program
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Effect test

Embodiment 1

[0062] figure 1 It is a flow chart of the method for shaping the output impedance of the converter of the present invention. like figure 1 As shown, a converter output impedance shaping method includes:

[0063] Step 101: Establish the impedance model of the converter grid-connected multi-machine system, and derive the system equivalent impedance ratio for evaluating the stability margin of the multi-machine interactive system and realizing system impedance optimization, specifically including:

[0064] Establish the single-machine impedance model of the converter.

[0065] The impedance network model of the multi-machine system is established by considering other components and circuit topology in the grid-connected multi-machine system of the converter according to the single-machine impedance model of the converter.

[0066] Considering the influence of frequency coupling effect according to the impedance network model of the multi-machine system, the system is equivalen...

Embodiment 2

[0082] Taking a wind farm grid-connected system connected with a static var generator (SVG) as an example, this embodiment provides a specific method for shaping the output impedance of a converter based on the optimal design of the control parameter particle swarm algorithm, including the following steps:

[0083] (1) Establish the impedance model of the converter grid-connected multi-machine system, and derive the system equivalent impedance ratio for evaluating the stability margin of the multi-machine system and realizing system impedance optimization. The sequence impedance model matrix Y of SVG stand-alone machine is derived based on harmonic linearization theory ST (s). Express the sequence impedance (admittance) of other converters, transmission lines and transformers in the wind farm as Y ST (s) Similar matrix form. Connect these impedances to each other according to the network topology, construct the impedance network of the wind farm, and derive the impedance mod...

Embodiment 3

[0101] Using the converter output impedance shaping method proposed in the present invention, the output impedance of SVG in a new energy power generation system of a wind farm in western my country is reshaped. figure 2 It is a structural diagram of the new energy power generation system described in Embodiment 3 of the present invention, in which the wind farm is equipped with 11 4.5MW wind turbines with parallel filter capacitors and 600V / 35kV transformers. The first electrical link is composed of 3 fan units, the second electrical link is composed of 4 fan units, and the remaining fan units form the third electrical link. These 3 electrical chain links are gathered at the 35kV busbar, and the 35kV voltage is transformed by a 35kV / 110kV, 110kV / 220kV two-stage transformer and finally connected to the power grid. The lengths of the power cables connecting the adjacent wind turbines in the three electrical chain links and connecting the wind turbines to the 35kV bus are 1km, ...

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Abstract

The invention relates to a converter output impedance shaping method and system. The method includes: establishing the impedance model of the converter grid-connected multi-machine system, deriving the system equivalent impedance ratio for evaluating the stability margin of the multi-machine interactive system and realizing system impedance optimization; based on the control structure of the converter and the control loop Performance index, deduce the design expression of the converter control parameters, and design the intelligent algorithm solution space to ensure the dynamic and steady-state performance of the single converter; abstract the converter control parameter optimization into a combinatorial optimization problem, in order to pass the system, etc. The phase margin obtained by the effective impedance ratio is the optimization target, and the optimal parameters are solved in the solution space of the intelligent algorithm by using the intelligent algorithm to complete the shaping of the output impedance of the converter. The invention enables the converter to maximize the stability margin of the system while ensuring its own performance index, and prevent the occurrence of system oscillation.

Description

technical field [0001] The invention relates to the technical field of converter control, in particular to a method and system for shaping the output impedance of a converter. Background technique [0002] With the development of new energy power generation technology in China, a large number of power electronic conversion devices are connected to the power system. As the interface equipment of the power system, the power electronic converter has complex coupling relationship and The interaction significantly affects the dynamic characteristics of the traditional power system, and at the same time brings challenges to the stability of the system. At present, the impedance analysis method has become an important means to study and solve the above stability problems. Reshaping the output impedance of the converter can realize the impedance optimization of the multi-machine interactive system, thereby enhancing the system robustness and preventing system oscillation. [0003]...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G05B13/04
CPCG05B13/042
Inventor 张旸王宇清陈新陈杰龚春英
Owner NANJING UNIV OF AERONAUTICS & ASTRONAUTICS