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Direct current system protection method and device based on recovery voltage gradient

A technology for restoring voltage and DC systems, applied to emergency protection circuit devices, electrical components, etc., can solve problems such as poor reliability and stability of DC systems, and achieve the effects of improving reliability and stability, increasing speed, and being easy to implement

Pending Publication Date: 2022-07-15
NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] In view of the above analysis, the embodiment of the present invention aims to provide a DC system protection method and device based on the recovery voltage gradient to solve the problem of DC system failure caused by failure to judge the fault type before performing the restart operation in the existing DC protection method. The problem of poor reliability and stability

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  • Direct current system protection method and device based on recovery voltage gradient
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  • Direct current system protection method and device based on recovery voltage gradient

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Embodiment 1

[0055] A specific embodiment 1 of the present invention discloses a DC system protection method based on recovery voltage gradient. The flow chart is as follows figure 1 shown, including the following steps:

[0056] S1. Determine the operating parameters of the DC system rectifier station, the DC line and the inverter station, and the parameters of the AC system connected to the inverter station, and obtain the restoration voltage gradient threshold value according to the operation parameters and the AC system parameters.

[0057] During implementation, the operating parameters of the DC system rectifier station, DC line and inverter station include: the equivalent resistance of the equivalent branch of the rectifier station, the DC line resistance, the DC line-to-ground conductance, and the effective value of the AC side line voltage of the inverter station. , DC line-to-ground equivalent capacitance, and inverter station trigger angle; the parameters of the AC system connec...

Embodiment 2

[0135] A specific embodiment 2 of the present invention discloses a DC system protection device based on the recovery voltage gradient, such as Figure 5 shown, including:

[0136] The recovery voltage gradient threshold value calculation module is used to determine the operation parameters of the DC system rectifier station, the DC line and the inverter station, and the parameters of the AC system connected to the inverter station, and obtain the recovery voltage according to the operation parameters and the AC system parameters. gradient threshold;

[0137] The measured recovery voltage gradient calculation module is used to collect the recovery voltage at the outlet of the inverter station of the DC system in the de-dissociation stage, and obtain the measured recovery voltage gradient according to the recovery voltage;

[0138] a fault type judgment module, used for judging the fault type of the DC system based on the restoration voltage gradient threshold value, the measu...

Embodiment 3

[0143] In order to verify the validity of Embodiment 1 and Embodiment 2 of the present invention, a specific embodiment 3 of the present invention is constructed as follows: Image 6 Take the DC system simulation structure diagram shown as an example, set the DC system operating parameters as: R d =5Ω, C=2.6×10 -6 F, G = 1 × 10 -5 S, the inverter station firing angle α=120° during the de-isolation period, the equivalent resistance of the rectifier station valve off state is 1.33×10 8 Ω, the effective value of the line voltage on the inverter side is U=209.23kV, the frequency is 50Hz, and the total de-free time is 500ms. In this way, the maximum value f of the recovery voltage gradient at the moment when the fault disappears is obtained. max =-1298.3, and then get the recovery voltage gradient threshold f set =-389.5.

[0144] Considering the applicability of the present invention, two scenarios of transient fault and permanent fault are respectively set in the line in thi...

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Abstract

The invention relates to a direct current system protection method and device based on recovery voltage gradient, belongs to the technical field of direct current system protection, and solves the problem of poor reliability and stability of a direct current system due to the fact that a fault type is not judged before a restart operation is executed in a direct current protection method in the prior art. The method comprises the following steps: determining operation parameters of a direct-current system rectification station, a direct-current line and an inverter station and parameters of an alternating-current system connected with the inverter station, and obtaining a recovery voltage gradient threshold value according to the operation parameters and the parameters of the alternating-current system; collecting a recovery voltage of an inverter station outlet of the direct current system in the deionization stage, and obtaining an actually measured recovery voltage gradient according to the recovery voltage; judging the fault type of the direct current system based on the recovery voltage gradient threshold value, the actually measured recovery voltage gradient and the instantaneous / permanent fault criterion; and sending a control signal according to the fault type, and controlling restarting or locking of the direct current system so as to realize protection of the direct current system.

Description

technical field [0001] The invention relates to the technical field of DC system protection, in particular to a DC system protection method and device based on a recovery voltage gradient. Background technique [0002] In the line commutated converter based high voltage direct current (LCC-HVDC) system, the DC transmission line spans a wide area, the working environment is complex and harsh, and the failure rate is high, and most of them are transient failures. The failure of the DC line will endanger the safe operation of electrical equipment, interrupt the normal transmission of power, and the blocking and outage of the DC system will cause system voltage and frequency stability problems and even cause a large power outage. It is particularly important to improve the reliability of power supply and maintain the stability of the entire system. [0003] Different from the AC transmission system, the fault current of the DC system does not have a natural zero-crossing point,...

Claims

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Application Information

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IPC IPC(8): H02H7/26
CPCH02H7/268
Inventor 马静刘晨黄韦博郝川均
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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