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Direct-current monopolar grounding fault detection method for flexible direct-current transmission system

A unipolar ground fault and power transmission system technology, applied in the field of flexible power transmission and distribution, can solve the problems that unipolar ground voltage is easily affected by other DC faults or AC faults, complex structure, cumbersome procedures, etc. Easy to operate, avoid misjudgment and misjudgment effects

Inactive Publication Date: 2016-05-04
TBEA SUNOASIS +2
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0006] In the currently used DC ground fault method, only the single-pole-to-ground voltage is used as the detection index, which is easily affected by other DC faults or AC faults, resulting in misjudgment; The converter station communicates, the structure is complex, and the procedure is cumbersome

Method used

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  • Direct-current monopolar grounding fault detection method for flexible direct-current transmission system
  • Direct-current monopolar grounding fault detection method for flexible direct-current transmission system
  • Direct-current monopolar grounding fault detection method for flexible direct-current transmission system

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Embodiment 1

[0046] Example 1, such as figure 2 , image 3 As shown, including the valve-side transformer and the converter station connected with the valve-side transformer through star-delta, as well as smoothing reactors and DC circuit breakers at the positive and negative stages of the DC bus. The valve-side transformer adopts the star-delta connection method. There are four fault monitoring points, including ① positive DC bus current change rate, ② negative DC bus current change rate, ③ positive DC bus voltage to ground, and ④ negative DC bus voltage to ground. Compare each selected parameter with the corresponding limit value Udcset, dIset, the specific discriminant formula is as follows:

[0047] 1. When the absolute value of the positive pole-to-ground voltage is less than the voltage comparison limit Udcset, the duration exceeds Tset.

[0048] 2. The absolute value of the rate of change of the positive DC current is greater than the first comparative limit value dIset of the ra...

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Abstract

The invention discloses a direct-current monopolar grounding fault detection method for a flexible direct-current transmission system. Turn-ground voltages of direct-current buses and current change rates of the positive and negative direct-current buses are obtained as direct-current monopolar grounding fault judgment parameters; when duration that an absolute value of the turn-ground voltage of one pole is smaller than a voltage comparison limit value Udcset exceeds a time limit value Tset, the duration that the absolute value of the direct-current change rate of the pole is greater than a current change rate comparison limit value dIset exceeds the time limit value Tset, and meanwhile, the duration of the absolute value of the direct-current change rate of another pole is smaller than a second current change rate comparison limit value dIset exceeds the Tset, the grounding fault of the pole is determined, so that erroneous judgment and misjudgment caused by other faults are avoided; meanwhile, the fault pole with the grounding fault can be detected; the accuracy for judging the direct-current monopolar grounding fault is improved; the fault can be detected through on-site measurement in a single convertor station; and the method is simple in program and easy to operate, and can quickly and accurately identify the direct current fault of the flexible direct-current transmission system.

Description

technical field [0001] The invention belongs to the technical field of flexible power transmission and distribution, and relates to a method for detecting a DC single-pole ground fault in a flexible DC transmission system. Background technique [0002] The first generation of HVDC transmission was based on mercury arc valves, and the second generation of HVDC technology was based on thyristors. In the late 1990s, voltage source converters (VSC) based on turn-off devices and pulse width modulation (PWM) technology began to be applied. In direct current transmission, it marks the birth of the third generation of flexible direct current transmission technology. [0003] The flexible direct current transmission system consists of a converter station and a direct current transmission line. Power can flow in both directions, and either of the two converter stations can operate as either a rectifier station or an inverter station. [0004] HVDC transmission line is an important p...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/36G01R31/08
CPCG01R31/085H02J3/36Y02E60/60Y04S10/52
Inventor 李辰侯丹张荣华刘伟增郝翔陈名汤明杰刘汉军
Owner TBEA SUNOASIS
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