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A UHV DC line protection method based on the distribution parameter model and using the current mutation characteristics

A distributed parameter model, UHV DC technology, applied in the direction of emergency protection circuit devices, electrical components, etc., can solve problems such as susceptibility to lightning interference, failure to consider capacitive current and data asynchronous, limited ability to withstand transition resistance, etc. It achieves the effects of strong anti-lightning interference ability, low sampling rate and small communication volume

Active Publication Date: 2019-01-11
CHINA THREE GORGES UNIV
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  • Description
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Problems solved by technology

For example, using the mutation of the current at both ends of the line to identify faults inside and outside the zone is a simple and feasible UHV DC line protection scheme (Gao Shuping, Suonan Jiale, Song Guobing, Zhang Jiankang, Hou Zhuo. High-voltage A new principle of longitudinal protection for DC transmission lines [J]. Electric Power System Automation, 2011, 35(05): 52-56.), but this scheme does not take into account the impact of long line distributed capacitance current and data asynchronous, while withstanding Transition resistance has limited capability and is susceptible to lightning interference

Method used

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  • A UHV DC line protection method based on the distribution parameter model and using the current mutation characteristics
  • A UHV DC line protection method based on the distribution parameter model and using the current mutation characteristics
  • A UHV DC line protection method based on the distribution parameter model and using the current mutation characteristics

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Embodiment

[0085] according to Figure 7 As shown in the system scheme diagram, a ±800kV UHV DC transmission model is built, the total length of the line is 1418km, the DC rated current is 3.125kA, I set Selected as 0.1pu, namely 0.3125kA. On this model, according to the method of the present invention, the faults at different positions of the positive pole line of the UHV DC transmission system are judged.

[0086] When the midpoint of the positive DC line is at 0.5s, it is grounded through a 200Ω transition resistance, and the fault time is 0.5s. The result is as follows Figure 8 shown. Figure 8 Among them, the first picture is the original current waveform collected by the positive DC line current transformer, and the second picture is the current waveform after capacitive current compensation and low-pass filtering processing by IED. Depend on Figure 8 It can be seen that after the fault, the current on the rectifier side of the positive DC line increases, the current on the i...

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Abstract

The invention discloses a UHV DC transmission line protection method utilizing current abrupt change characteristics based on a distributed parameter model. The UHV DC transmission line protection method comprises the steps of processing voltage and current signals measured by transformers at both ends of a DC line by means of an intelligent electronic device (IED), and identifying internal and external faults according to polarities of current abrupt variables. The UHV DC transmission line protection method adopts a distributed parameter model for carrying out distributed capacitive current compensation, eliminates the influence of asynchronization of the distributed capacitive current and data. A protection criterion selects components with the frequency band of [0,100] Hz in current information, avoids the electromagnetic coupling between DC side characteristic harmonics and a bipolar DC line and the influence of lightning interference. The polarities of current abrupt variables at both ends of the line are Boolean quantities, and the communication traffic of longitudinal channels is small. The UHV DC transmission line protection method utilizing the current abrupt change characteristics based on the distributed parameter model only utilizes polarities of the current abrupt variables for identifying the internal and external faults, is simple in principle and small in communication traffic, and is stable and reliable.

Description

technical field [0001] The invention belongs to the field of relay protection of electric power systems, and in particular relates to a method for protecting UHV direct current lines based on distribution parameter models and utilizing the characteristics of sudden changes in current. Background technique [0002] UHV DC transmission has been widely used in long-distance, large-capacity power transmission and regional interconnection, but the reliability of relay protection in UHV DC transmission projects is still significantly low, especially the protection of DC lines. Therefore, it is urgent to study new stable and reliable UHVDC transmission line protection methods with fast response, strong resistance to transition resistance, anti-lightning interference, and absolute selectivity. [0003] Traveling wave protection is the main protection of existing UHV DC line protection. The methods to improve the performance of traveling wave protection mainly focus on two aspects: o...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26
CPCH02H7/268
Inventor 李振兴谭洪孟晓星王玲叶诗韵李振华翁汉琍姚远龙子琦
Owner CHINA THREE GORGES UNIV
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