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Method for judging internal and external faults of direct-current line area of hybrid direct-current power transmission system

A technology of direct current transmission lines and transmission systems, which is applied in the field of power systems, can solve problems such as insufficient sensitivity, and achieve the effects of clear principles, fast action speed, and strong practical value

Pending Publication Date: 2021-02-12
XIAN UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] The purpose of the present invention is to provide a method for distinguishing faults inside and outside the DC line area of ​​a hybrid direct current transmission system, so as to solve the problem of insufficient sensitivity existing in the application of the traditional high voltage direct current transmission line traveling wave protection and transient protection to the hybrid flexible direct current transmission system

Method used

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  • Method for judging internal and external faults of direct-current line area of hybrid direct-current power transmission system
  • Method for judging internal and external faults of direct-current line area of hybrid direct-current power transmission system
  • Method for judging internal and external faults of direct-current line area of hybrid direct-current power transmission system

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Embodiment 1

[0073] Such as figure 2 Shown is a simulation model diagram of a LCC-VSC hybrid DC transmission system. The rated DC voltage of the system is ±500kV, and the rated transmission power is 1200MW. The inductance value of the smoothing reactor in the LCC converter station is 300mH, and the DC filter adopts 12 / 24 and 24 / 36 double-tuned filter banks. The inductance value of the smoothing reactor in the VSC converter station is 20mH, and the DC capacitance value is 200μF. The DC line is 1000km long, and the ground electrode lead is 38km long. They are all simulated by the overhead line model with frequency variable parameters, and the pole address resistance is taken as 0.2Ω.

[0074] When a line fault occurs in the system, the method provided by the invention can quickly and correctly judge whether the fault is an internal fault or an external fault. The following describes four typical faults, including external fault F1, metal grounding fault on the valve side of the positive ...

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Abstract

The invention discloses a method for judging internal and external faults of a direct-current line area of a hybrid direct-current power transmission system. The method comprises the steps of 1 takinga time data window after a protection starting element is started, and calculating a fault component, a line-mode voltage fault component, a line-mode current fault component and a line-mode voltagereverse traveling wave therein; 2 calculating a sampling point ks and a minimum value of a reverse traveling wave change rate in two points after the sampling point ks, and recording the minimum valueas dub / dt_m<3>; 3 setting a threshold value th1, comparing the threshold value th1 with -dub / dt_m <3>, and judging whether the fault is a line external fault or not; 4 finding out a sampling point corresponding to a reverse traveling wave descending end moment caused by the fault first traveling wave through point-by-point comparison; 5 calculating a descending amplitude value A under the fault first traveling wave; 6 calculating a reverse traveling wave variable quantity S in the remaining data window; 7 calculating the ratio R of the reverse traveling wave variable quantity to the decreasing amplitude value under the fault first traveling wave; and 8 setting a threshold value th2, comparing the threshold value th2 with R, and judging whether the fault is a fault in the line area. The method is higher in sensitivity, and can distinguish high-resistance faults.

Description

technical field [0001] The invention belongs to the technical field of power systems, and relates to a method for distinguishing faults inside and outside the DC line area of ​​a hybrid direct current transmission system. Background technique [0002] The traditional HVDC transmission technology based on grid-commutated converters (LCCs) has been maturely applied to long-distance large-capacity power transmission and power networking. However, since the converter components use semi-controlled power electronic device thyristors, the system completely relies on the AC power grid to operate, and the inverter station is prone to commutation failure, especially in the multi-infeed DC system, it is easy to cause cascade commutation of multiple converter stations failure with serious consequences. The voltage source converter (VSC) high-voltage direct current transmission based on fully controlled devices does not rely on the AC grid voltage to support the operation, and can supp...

Claims

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Application Information

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IPC IPC(8): G01R31/08
CPCG01R31/085G01R31/088
Inventor 王艳婷谢凡成少杰张保会
Owner XIAN UNIV OF TECH
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