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Low-voltage direct-current power distribution network node inertia evaluation method based on contribution factors

A low-voltage DC and distribution network technology, applied in the direction of instruments, complex mathematical operations, data processing applications, etc., can solve the problem of not giving the calculation method of the inertia index of the evaluation node, not considering the role of the controller parameters, and not recognizing the low-voltage DC distribution network. Problems such as the distribution characteristics of the power grid, to achieve the effects of clear physical meaning, guaranteed accuracy, and high evaluation accuracy

Active Publication Date: 2021-11-26
中国能源建设集团天津电力设计院有限公司 +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Defects in the existing technology: 1) The role of controller parameters is not considered, and the evaluation of the node inertia of the low-voltage DC power distribution system only considers the capacitance value of the access node and the virtual The connection value of inertia, but in fact, the node inertia depends not only on the capacitance value or virtual capacitance value of the connection node, but also depends on the control mode and control parameters of the connection node converter; 2) The current technical scheme does not consider DC The distribution characteristics of the voltage inertia of the distribution network. The current technical scheme only considers the inertia index evaluation of the bus nodes in the low-voltage DC distribution system, but does not recognize the distribution characteristics of the inertia of the low-voltage DC distribution network nodes. The distribution characteristics come from the system structure and parameters of each line; 3) The impact of DC load fluctuations on the inertia of the DC distribution network is not considered. The current technical plan considers that the node inertia index has nothing to do with the external input, and believes that the node inertia is an inherent property of the system, but in fact, when considering When considering the distribution characteristics of node inertia, the inertia distribution of each node needs to take into account the influence of DC load conditions, and the evaluation of node inertia needs to be calculated on a certain input basis; 4) The specific index calculation method for evaluating node inertia is not given. The current technical scheme does not consider the above influencing factors, and the evaluation index is only the capacitance value or virtual capacitance value of the access node, which cannot accurately evaluate the node inertia of the low-voltage DC power distribution system

Method used

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  • Low-voltage direct-current power distribution network node inertia evaluation method based on contribution factors
  • Low-voltage direct-current power distribution network node inertia evaluation method based on contribution factors
  • Low-voltage direct-current power distribution network node inertia evaluation method based on contribution factors

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Effect test

Embodiment 1

[0111] see attached image 3 , for a 4-node DC distribution network composed of one AC / DC interface converter (AC / DC) and two load DC converters (DC / DC), the time scale of the system inertia characteristics is relatively large, so we can only focus on the transformation According to the outer loop characteristics of the converter, the AC / DC interface converter (AC / DC) with droop control can be equivalent to a constant voltage source with internal resistance, and the load DC converter (DC / DC) can be equivalent to a current source, such as image 3 As shown in the figure: U dcref is the DC reference voltage, K G is the droop coefficient, C dc is the DC bus side filter capacitor, u dc (t) is the DC bus voltage, I L1 is the equivalent current source of load 1, C L1 is load 1 DC converter filter capacitor, R 1 is load 1 line resistance, u L1 (t) is the DC voltage at port 1 of the load, I L2 is an equivalent current source for the load 2, C L2 is the load 2 DC converter fil...

Embodiment 2

[0149] For a 3-node DC distribution network composed of one AC / DC interface converter (AC / DC) and one load DC converter (DC / DC), the AC / DC interface converter (AC / DC) with droop control will still be used. / DC) can be equivalent to a constant voltage source with internal resistance, and the load DC converter (DC / DC) can be equivalent to a current source, Figure 5 Middle image: U dcref is the DC reference voltage, K G is the droop coefficient, C dc is the DC bus side filter capacitor, u dc (t) is the DC bus voltage, I L is the load equivalent current source, C L is the load DC converter filter capacitor, R is the load line resistance, u L (t) is the DC voltage at the load port.

[0150] The system parameters are shown in the table below.

[0151] Table 2 System parameters of three-node voltage DC distribution network

[0152] describe parameter parameter value reference voltage U dcref

400V Droop coefficient K G

0.05 DC bus side fil...

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Abstract

The invention relates to a low-voltage direct-current power distribution network node inertia evaluation method based on contribution factors, which comprises the following steps: introducing a modal matrix to decompose the dynamic process of each node state variable into basic mode components, calculating the contribution factors of the basic mode components to each state variable, calculating a value time interval for least square index fitting, and calculating an equivalent time constant of least square exponential fitting, and calculating a node inertia index. The method has the advantages that the modal matrix is introduced, the dynamic process of each node state variable is decomposed into superposition of a series of basic modes, and each basic mode has the determined attenuation characteristic; contribution factors are defined, a node inertia evaluation method based on the contribution factors is provided, and it is pointed that the contribution factors of all modes are related to a system structure, system parameters and input parameters; a value time interval selection method and an equivalent time constant calculation method based on least square exponential fitting are provided, the curve fitting precision is guaranteed, and the evaluation accuracy is high.

Description

technical field [0001] The invention belongs to low-voltage direct current power distribution technology, in particular to a low-voltage direct current distribution network node inertia evaluation method based on contribution factors. Background technique [0002] The low-voltage DC power distribution system is mainly composed of AC / DC interface converters (AC / DC), DC converters (DC / DC), energy storage devices, distributed power generation, DC loads, control and protection equipment, etc. A typical low-voltage DC distribution network structure is as follows: figure 2 As shown, considering that distributed power generation such as micro wind turbines and small-scale photovoltaic power generation usually operates in the maximum power tracking mode, the generated power has fluctuations and is equivalent to being connected to the system in the form of a current source, so it is equal to the DC load or with the DC load constitutes a net DC load, therefore, at figure 1 Distribu...

Claims

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Application Information

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IPC IPC(8): G06Q10/06G06Q50/06G06F17/11G06F17/16
CPCG06Q10/06393G06Q50/06G06F17/11G06F17/16
Inventor 李学斌刘建伟刘晓鸥陈世龙马麟
Owner 中国能源建设集团天津电力设计院有限公司
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