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Flexible direct-current high-frequency resonance suppression method based on voltage feedforward nonlinear filtering

一种非线性滤波、非线性滤波器的技术，应用在电力传输交流网络、程序控制、电气元件等方向，能够解决影响柔性直流输电系统交流故障穿越性能、增加电压前馈环节延时、无法完全滤除高频段谐波等问题

Active Publication Date: 2019-05-24
BEIJING SIFANG JIBAO AUTOMATION +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, because the low-pass filter cannot completely filter out the harmonics in the high-frequency band, this solution further increases the delay of the voltage feedforward link, which will shift the high-frequency resonance to a lower frequency direction, resulting in mid-high frequency resonance. It will also affect the AC fault ride-through performance of the flexible DC transmission system

Method used

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  • Flexible direct-current high-frequency resonance suppression method based on voltage feedforward nonlinear filtering
  • Flexible direct-current high-frequency resonance suppression method based on voltage feedforward nonlinear filtering
  • Flexible direct-current high-frequency resonance suppression method based on voltage feedforward nonlinear filtering

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Embodiment

[0092] The embodiment is as follows: Assume that the D-axis positive sequence voltage component U after Parker transformation is dp The value is 1.01p.u. Take the sampling value of this period together with the previous 19 periods, a total of 20 points are used for average filtering calculation, assuming that the average value is still 1.01p.u., when passing through the nonlinear filter for the first time, the initial value of the filter is 0 , to calculate the deviation D between the average value of each voltage sequence component and the output result of the nonlinear filter in the previous cycle udp_y = 1.01, the judgment deviation 1.01 is greater than the preset threshold value 0.15, and the output result of the nonlinear filter in this cycle is V udp It is equal to the output value 0 of the previous cycle plus the preset nonlinear order gradient 0.2, that is, 0.2, V udp Acting on the voltage feed-forward link of the positive sequence D-axis current inner loop, the proce...

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Abstract

The invention discloses a flexible direct-current high-frequency resonance suppression method based on voltage feedforward nonlinear filtering. According to the invention, during the inner loop controlling process of a flexible direct-current current, the nonlinear filtering is carried out for a voltage feedforward link. The method specifically comprises the following steps: extracting each sequence component of an alternating-current voltage amplitude; calculating the N sampling point average values of the sequence components; comparing a current average value with the output result of a nonlinear filter in a previous period; and correcting the output result of the nonlinear filter in a current period. The output result is a fixed value which changes in a gradient mode and acts on the voltage feedforward link of the inner loop. The beneficial effects of the invention are as follows: the high-frequency resonance of a flexible direct-current and alternating-current system caused by impedance matching can be effectively inhibited. Meanwhile, the rapidity is achieved and the adjustment can be carried out along with alternating voltage when voltage disturbance such as alternating current faults occurs. The over-current risk of the converter valve is reduced. The method only needs to be achieved in the flexible direct-current secondary control software link, wherein no primary device needs to be additionally arranged. The method is low in cost, free of land occupation and convenient for engineering practice.

Description

technical field [0001] The invention relates to a flexible direct current transmission system, which belongs to the technical field of high voltage transmission; more specifically, it relates to a method for suppressing high frequency resonance of a flexible direct current transmission system. Background technique [0002] There is a risk of high-frequency resonance between the flexible DC transmission system and the AC system. The main reason is that the control link of the flexible DC transmission system is complex, which is usually formed in series by the measurement link, unit control system, valve pole control system, etc., which includes link communication And the time delay brought by the calculation and processing, the delay will produce negative damping characteristics in the closed-loop control, and the voltage feedforward link accounts for the main part. If the AC system also exhibits weak damping characteristics in the high frequency band, then the flexible DC an...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/36H02J3/01
CPCH02J3/36Y02E60/60H02J2003/365H02J3/241G05B2219/25409H02J3/24
Inventor 刘斌操丰梅刘树梅红明刘志超秦红霞张效宇于华龙郭贤朝文晶
Owner BEIJING SIFANG JIBAO AUTOMATION
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