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A method and system for distance protection of AC lines in an AC-DC hybrid power grid

An AC-DC hybrid, distance protection technology, applied in AC network circuits, power transmission AC networks, circuit devices, etc., can solve the problems of DC system commutation failure, refusal, and traditional distance protection misoperation, etc., to improve accuracy. the effect of reducing the chance of refusal or accidental movement

Active Publication Date: 2021-09-07
NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] However, the above-mentioned distance protection method is only applicable to pure AC systems. With the large-scale DC system connected to the AC grid, the commutation failure of the DC system caused by the fault on the AC side will cause the converter station to exhibit nonlinear time-varying fault characteristics. May cause traditional distance protection to malfunction or refuse to operate

Method used

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  • A method and system for distance protection of AC lines in an AC-DC hybrid power grid
  • A method and system for distance protection of AC lines in an AC-DC hybrid power grid
  • A method and system for distance protection of AC lines in an AC-DC hybrid power grid

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0149] The A-phase grounding fault and the AB two-phase grounding fault are respectively set at 50% of the AC line, and the transition resistance varies from 0 to 300Ω.

[0150] When there is no fault in the AC / DC hybrid grid, such as figure 2 Both the Y-bridge inverter and the D-bridge inverter shown are normally commutated. At t=0ms, the Y-bridge converter is in the conduction state of VTY1 and VTY2, and the D-bridge converter is in the conduction state of VTD1 and VTD2. Under the action of the trigger signal of the Y-bridge converter VTY3 and the D-bridge converter VTD3 , the Y-bridge converter and the D-bridge converter are commutated successively. When the voltage of the D-bridge converter VTD1 changes from negative to positive for the first time and its blocking capability is restored, the Y-bridge converter and the D-bridge converter commutate. The inverter completes commutation. At this time, the Y-bridge inverter is in the conduction state of VTY2 and VTY3, and the ...

Embodiment 2

[0159] The A-phase grounding fault and the AB-phase-to-phase fault are respectively set at different positions in the AC line area. When the A-phase grounding fault occurs, the transition resistance is 300Ω.

[0160] At t=0ms, the Y-bridge converter is in the conduction state of VTY1 and VTY2, and the D-bridge converter is in the conduction state of VTD1 and VTD2. Under the action of the trigger signal of the Y-bridge converter VTY3 and the D-bridge converter VTD3 , the Y-bridge converter and the D-bridge converter are commutated successively. When the voltage of the D-bridge converter VTD1 changes from negative to positive for the first time, the conduction states of the Y-bridge converter and the D-bridge converter are as follows: Table 2 shows:

[0161] Table 2 The conduction state of the converter when the A-phase ground fault and the AB-phase-to-phase fault occur at different positions of the AC line

[0162]

[0163] It can be seen from Table 2 that when an AB phase-...

Embodiment 3

[0168] exist figure 2 The ground fault of phase A is set at f1 in the middle, and the variation range of the transition resistance is 0~300Ω.

[0169] At t=0ms, the Y-bridge converter is in the conduction state of VTY1 and VTY2, and the D-bridge converter is in the conduction state of VTD1 and VTD2. Under the action of the trigger signal of the Y-bridge converter VTY3 and the D-bridge converter VTD3 , the Y-bridge converter and the D-bridge converter are commutated successively. When the voltage of the D-bridge converter VTD1 changes from negative to positive for the first time, the conduction states of the Y-bridge converter and the D-bridge converter are as follows: Table 3 shows:

[0170] Table 3 The conduction state of the converter when the DC system on the back side of the AC line fails

[0171]

[0172]

[0173] It can be seen from Table 3 that when the transition resistance is 0Ω, the Y-bridge converter VTY1 fails to restore the blocking capability during the ...

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Abstract

The invention relates to a distance protection method and system for an AC line of an AC-DC hybrid power grid, belonging to the technical field of high-voltage direct current transmission. The method includes: collecting operating parameters, AC parameters, commutation bus voltage, and distance protection installation The current at the inverter station and the operating parameters of the smoothing reactor in the inverter station; according to the operating parameters of the inverter side converter, determine the conduction state of the inverter side converter; according to the operating parameters of the inverter side converter, the inverter The operating parameters of the smoothing reactor in the substation and the voltage of the commutation busbar determine the current fed into the AC system by the DC system corresponding to the conduction state; determine the virtual fault location and virtual transition resistance according to the fault type and AC parameters; And virtual transition resistance, control the corresponding protection device to perform protection action. The invention predicts the fault location aiming at the non-linear time-varying fault characteristics of the converter station, thereby reducing the probability of refusal or malfunction of the protection device when the converter station presents nonlinearity.

Description

technical field [0001] The invention relates to the technical field of high-voltage direct current power transmission, and in particular, to a method and system for distance protection of alternating current lines in an alternating current and direct current hybrid grid. Background technique [0002] In recent years, with the wide application of HVDC transmission technology in the field of long-distance and large-capacity power transmission, the commutation failure of the DC system causes the AC side distance protection refusal to actuate and malfunction more frequently, which seriously affects the safety and stability of the power grid operation. sex. Therefore, it is of great practical significance to quickly and correctly isolate the AC side faults to ensure the safe operation of the AC-DC hybrid power grid. [0003] For AC line distance protection, some scholars have carried out relevant research, and the methods are mainly divided into three categories: traveling wave ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02H7/26H02J3/36G01R31/08
CPCH02H7/268H02J3/36G01R31/086G01R31/088Y02E60/60Y04S10/52H02M7/06H02J3/0012H02M1/325
Inventor 马静吴羽翀杨真缪周晓东
Owner NORTH CHINA ELECTRIC POWER UNIV (BAODING)
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