CN107526005B - Sudden change starting method of single-phase earth fault processing device - Google Patents
Sudden change starting method of single-phase earth fault processing device Download PDFInfo
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- H—ELECTRICITY
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Abstract
A sudden change starting method for single-phase earth fault processing device detects the displacement voltage of neutral point of power network in real time
And the maximum zero sequence current i of each feeder linemax0If the amount of sudden change in the neutral point voltage during the time period Δ T matches: Δ un≥ΔuNLMeanwhile, the stable break variable of the maximum zero sequence current of any feeder line meets the following conditions: i.e. imax0≥i0B+ΔiδIf the single-phase grounding occurs to the power grid, the grounding fault processing device enters fault starting to process the single-phase grounding fault; if in the time period
The mutation amount of the internal neutral point voltage accords with the following conditions: Δ uN≥ΔuNLBut the stable break variable i of the maximum zero sequence current of the feeder linemax0∠i0B+∠ΔiδIf the voltage is determined to be the neutral point displacement voltage caused by the power grid parameter change
The ground fault handling means is not activated; if the voltage abrupt change amount delta u of the neutral point of the power distribution network is within the time period delta TNDoes not reach Delaut continuouslyN≥ΔuNLOr maximum zero sequence current i of feedermax0Do not reach i continuouslymax0≥i0B+ΔiδIf the fault occurs, the ground fault processing device judges that unstable ground fault or intermittent ground leakage occurs in the power grid, and the ground fault processing device does not enter fault starting.
Description
Technical Field
The invention belongs to the field of single-phase earth fault processing of a power distribution network, and is mainly used for determining a fault starting method of an earth fault processing device when the power distribution network is in single-phase earth.
Background
When a single-phase earth fault occurs in a power distribution network, different earth fault processing devices need to set an entering fault starting value when performing fault processing, at present, the absolute value of the displacement voltage of the neutral point of the power grid is generally adopted as the fault starting value of the single-phase earth fault, and for the power grid adopting arc suppression coil compensation, the displacement voltage u of the neutral point is generally adoptedN≥uФ20 %（
Phase voltage) as a fault starting voltage value when processing a ground fault, but the power grid asymmetry factor is different due to different power grid parameters
And also different. The specification specifies that the asymmetry factor K is not grounded to the neutral pointcThe value range of (A) is 0-5%. Compensated by arc suppression coilsGrid, neutral point displacement voltage:
(v is the compensation grid detuning degree, d is the damping rate of the grid), the grid asymmetric coefficient can be known
And compensating the power grid detuning degree v to the neutral point displacement voltage
Has a great influence, such as shifting the voltage by only the neutral point
As the start value of the ground fault, it is likely to cause malfunction of the ground fault processing apparatus. Upper limit u of neutral point displacement voltage of power grid compensated by arc suppression coilN=uФ15%, but as
When there is
The fault dead zone of (a) cannot initiate fault handling. Non-grounded neutral point, asymmetry factor
The value range of (1) is 0-5%, if the power grid fault starting voltage is set, the asymmetry coefficient is calculated
When 0, u isФ5% fault dead band. For high-resistance earth faults caused by personal electric shock or wire breakage, the absolute value of the displacement voltage of the neutral point of the power grid is used as a fault starting value of the single-phase earth fault, and for high-resistance earth faults caused by personal electric shock or wire breakage, the fault starting value of the earth fault processing device can not be processed basically.
Disclosure of Invention
In order to solve the problem of fault starting of a ground fault processing device when a single-phase ground fault occurs in a power distribution network, the invention provides a sudden change starting method of the single-phase ground fault processing device, which is characterized in that the displacement voltage of a neutral point of the power grid is detected in real time
And the maximum zero sequence current i of each feeder linemax0And if the sudden change of the displacement voltage of the neutral point of the power grid in the time period delta T meets the following conditions: Δ uN≥ΔuNLMeanwhile, the maximum zero-sequence current of any feeder line meets the following conditions: i.e. imax0≥i0B+ΔiδIf the single-phase grounding occurs to the power grid, the grounding fault processing device enters fault starting to process the single-phase grounding fault; if the sudden change of the displacement voltage of the neutral point of the power distribution network in the time period delta T meets the following conditions: Δ uN≥ΔuNLBut the maximum zero-sequence current of the feed line: i.e. imax0<i0B+ΔiδIf the neutral point displacement voltage uN is determined to be changed due to the change of the power grid parameters, the ground fault processing device is not started; if the voltage abrupt change amount delta u of the neutral point displacement of the power distribution network in the time period delta TNΔ un ≧ Δ u is not continuously reachedNLOr maximum zero sequence current i of feedermax0There is no constant achievement of: i.e. imax0≥i0B+ΔiδIf the fault occurs, the ground fault processing device judges that unstable ground fault or intermittent ground leakage occurs in the power grid, and the ground fault processing device does not enter fault starting.
If the sudden change of the displacement voltage of the neutral point of the power grid in the time period delta T meets the following conditions: Δ uN≥ΔuNLMeanwhile, the maximum zero-sequence current of any feeder line meets the following conditions: i.e. imax0≥i0B+ΔiδAnd if the single-phase grounding occurs in the power grid, the grounding fault processing device enters fault starting to process the single-phase grounding fault.
If the sudden change of the displacement voltage of the neutral point of the power distribution network in the time period delta T meets the following conditions: Δ un≥ΔuNLBut the maximum zero-sequence current of the feed line: i.e. imax0<i0B+ΔiδJudging that the voltage is the neutral point displacement voltage u caused by the change of the power grid parametersNThe ground fault handling means is not activated.
If the voltage abrupt change amount delta u of the neutral point displacement of the power distribution network in the time period delta TNDoes not reach Delaut continuouslyn≥ΔuNLOr maximum zero sequence current i of feedermax0There is no constant achievement of: i.e. imax0≥i0B+ΔiδIf the fault occurs, the ground fault processing device judges that unstable ground fault or intermittent ground leakage occurs in the power grid, and the ground fault processing device does not enter fault starting.
The invention has the following advantages:
1. the method adopts a fault starting method of a stable break variable of neutral point displacement voltage, and solves the problem of a fault dead zone existing in the fault starting method adopting the absolute value of the neutral point displacement voltage of a power grid as a ground fault.
2. The method adopts a comprehensive comparison method of the stable break variable of the shift voltage of the neutral point and the maximum zero sequence current stable break variable of the feeder line, and an effective method for avoiding Wu judgment caused by a single criterion is avoided.
3. The method adopts a method of detecting time period delta T, and compares the detection time periods
The stable sudden change value of the relevant parameters avoids the influence of unstable disturbance of the ground-to-earth copy and intermittence on the ground leakage on the ground fault treatment.
Drawings
Fig. 1 is a logic diagram of a ground fault initiation method based on continuous increment of grid characteristic parameters.
Detailed Description
When the power distribution network normally operates, the voltage transformer installed at the neutral point of the power distribution network detects the displacement voltage u of the neutral point of the power distribution network in real timeNAs the steady-state voltage of the neutral point, the zero-sequence current i of each feeder line is detected in real time by a zero-sequence current transformer installed on each feeder line0BThen the zero sequence current increment delta i, i is superposedmax0=i0B+ Δ i, andΔ i and Δ iδCompared with the determination method (delta i) as to whether single-phase grounding occursδMay be set according to different grid configurations and operating environments). If the stable increment of the displacement voltage of the neutral point of the power distribution network in the time period delta T is consistent with the following conditions: Δ uN≥ΔuNLMeanwhile, the maximum zero-sequence current of any feeder line meets the following conditions: i.e. imax0≥i0B+ΔiδAnd if the single-phase grounding occurs in the power grid, the grounding fault processing device enters fault starting to process the single-phase grounding fault. If the sudden change of the displacement voltage of the neutral point of the power distribution network in the time period delta T meets the following conditions: Δ uN≥ΔuNLBut the maximum zero-sequence current of the feed line: i.e. imax0<i0B+ΔiδJudging that the voltage is the neutral point displacement voltage u caused by the change of the power grid parametersNIs changed, the earth fault handling means is not activated, in which case the neutral point is displaced by the voltage uN1=uN+ΔuNLIs a new neutral point steady state voltage; if the voltage abrupt change amount delta u of the neutral point displacement of the power distribution network in the time period delta TNDoes not reach Delaut continuouslyN≥ΔuNLOr maximum zero sequence current i of feedermax0Do not reach i continuouslymax0≥i0B+ΔiδIf the fault occurs, the ground fault processing device judges that unstable ground fault or intermittent ground leakage occurs in the power grid, and the ground fault processing device does not enter fault starting.
Time period
In order to check the stable time period of the transient variable and eliminate unstable disturbance, different ground fault processing modes and ground fault processing devices are set differently.
Continuous sudden change of displacement voltage of neutral point of power distribution network
The standard value for the fault starting can be set differently according to different ground fault processing modes and ground fault processing devices.
For the neutral point of the power grid compensated by the arc suppression coil, the neutral point displacement voltage is
The voltage u can shift to the neutral point when the operation mode of the power grid changesNInfluence is caused, and the inductance adjustment and residual current control of the arc suppression coil can also realize the displacement voltage u of the neutral pointNThe method for fault starting, which causes influence, comprises the following steps: the stable abrupt change of the displacement voltage of the neutral point of the power distribution network in the time period delta T meets the following conditions: Δ uN≥ΔuNLMeanwhile, the stable break variable of the maximum zero sequence current of any feeder line meets the following conditions: Δ i ≧ Δ iδIf the single-phase grounding occurs to the power grid, the grounding fault processing device enters fault starting to process the single-phase grounding fault; if in the time period
The stable increment of the displacement voltage of the neutral point of the internal distribution network conforms to the following conditions: Δ uN≥ΔuNLBut the mutation amount of the maximum zero sequence current of the feeder line is as follows: Δ i ≦ Δ iδJudging that the voltage is the neutral point displacement voltage u caused by the change of the power grid parametersNIs changed, the earth fault handling means is not activated, in which case the neutral point is displaced by the voltage uN1=uN+ΔuNLIs the new neutral point steady state displacement voltage. If the voltage abrupt change amount delta u of the neutral point displacement of the power distribution network in the time period delta TNDoes not reach Delaut steadilyN≥ΔuNLOr the maximum zero sequence current mutation of the feeder line is not stable to reach delta i more than or equal to delta iδIf the fault occurs, the ground fault processing device judges that unstable disturbance ground or intermittent ground leakage occurs in the power grid, and at the moment, the ground fault processing device does not enter fault starting and does not process the ground fault.
For a neutral ungrounded grid, the neutral displacement voltage is: u. ofN=kcuФThe fault starting method comprises the following steps: in a period of time
The stable abrupt change of the displacement voltage of the neutral point of the internal distribution network conforms to the following conditions: Δ uN≥ΔuNLMeanwhile, the stable break variable of the zero sequence current of any feeder line conforms to the following conditions: Δ i ≧ Δ iδIf the single-phase grounding occurs to the power grid, the grounding fault processing device enters fault starting to process the single-phase grounding fault; if the stable sudden change of the displacement voltage of the neutral point of the power distribution network in the time period delta T meets the following conditions: Δ uN≥ΔuNLHowever, the maximum zero sequence current break variable delta i of the feeder line is less than or equal to delta iδJudging that the voltage is the neutral point displacement voltage u caused by the change of the power grid parametersNIs changed, the earth fault handling means is not activated, in which case the neutral point is displaced by the voltage uN1=uN+ΔuNLIs the new neutral steady state voltage. If in the time period
Voltage sudden change of neutral point of internal distribution network
Does not reach Delaut steadilyN≥ΔuNLOr maximum zero sequence current i of feedermax0Do not reach i steadilymax0≥i0B+ΔiδIf the fault occurs, the ground fault processing device judges that unstable disturbance ground or intermittent ground leakage occurs in the power grid, and at the moment, the ground fault processing device does not enter fault starting and does not process the ground fault.
The above description is only a preferred embodiment of the present invention, and the protection scope of the present invention is not limited to the above embodiments, and all technical solutions belonging to the idea of the present invention belong to the protection scope of the present invention. It should be noted that several modifications and adaptations to those skilled in the art without departing from the principles of the present invention should also be considered within the scope of the present invention.
Claims (4)
1. A sudden change starting method of a single-phase earth fault processing device is characterized in that: by detecting the displacement voltage u of the neutral point of the power grid in real timeNAnd the maximum zero sequence current i of each feeder linemax0If the sudden change of the voltage of the neutral point of the power grid in the time period delta T meets the following conditions: Δ uN≥ΔuNLMeanwhile, the maximum zero-sequence current of any feeder line meets the following conditions: i.e. imax0≥i0B+ΔiδIf the single-phase grounding occurs to the power grid, the grounding fault processing device enters fault starting to process the single-phase grounding fault; if the sudden change of the neutral point voltage of the power distribution network in the time period delta T meets the following conditions: Δ uN≥ΔuNLBut the maximum zero-sequence current of the feed line: i.e. imax0<i0B+ΔiδJudging that the voltage is the neutral point displacement voltage u caused by the change of the power grid parametersNThe ground fault handling means is not activated; if the voltage abrupt change amount delta u of the neutral point of the power distribution network is within the time period delta TNDoes not reach Delaut continuouslyN≥ΔuNLOr maximum zero sequence current i of feedermax0There is no constant achievement of: i.e. imax0≥i0B+ΔiδIf so, judging that unstable disturbance ground or intermittent ground leakage occurs in the power grid, and at the moment, the ground fault processing device does not enter fault starting; the time period delta T is the duration of the test break variable; Δ uNLStarting a standard value for the continuous sudden change fault of the neutral point voltage of the power distribution network; i.e. i0BFor zero sequence current values, Δ i, detected during normal operation of each feeder lineδThe zero sequence current sudden change critical value is the sudden change critical value when single-phase grounding occurs.
2. The abrupt starting method of the single-phase ground fault handling device according to claim 1, wherein: the delta T is used for eliminating unstable disturbance, and different ground fault processing modes and ground fault processing devices are set differently.
3. The method of claim 1A sudden change starting method of a single-phase earth fault processing device is characterized in that: Δ uNLDifferent settings can be made according to different ground fault handling modes and ground fault handling devices.
4. The abrupt starting method of the single-phase ground fault handling device according to claim 1, wherein: Δ iδDifferent settings can be made according to different power grid structures and ground fault handling devices.
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| CN109031035A (en) * | 2018-02-07 | 2018-12-18 | 李景禄 | A kind of otherness one-phase earthing failure in electric distribution network property and fault recovery judgment method |
| CN108287296B (en) * | 2018-02-07 | 2020-07-28 | 李景禄 | High-resistance grounding fault reverse starting and line selection method suitable for asymmetric power grid |
| CN108321779B (en) * | 2018-03-12 | 2019-07-05 | 李景禄 | A kind of ground fault Intelligent treatment method of Modes for Neutral |
| CN109633376A (en) * | 2018-12-21 | 2019-04-16 | 国网北京市电力公司 | Handle the method and device of singlephase earth fault |
| CN110031716B (en) * | 2019-03-26 | 2020-12-08 | 国电南瑞科技股份有限公司 | Distributed fault detection method for power distribution system with resonant grounding |
| CN110632439A (en) * | 2019-09-29 | 2019-12-31 | 国网河南省电力公司电力科学研究院 | Power distribution network single-phase earth fault diagnosis technology based on synchronous waveform and association rule |
| CN112152191B (en) * | 2020-09-01 | 2022-05-31 | 国网陕西省电力公司榆林供电公司 | Fault processing method, device and storage medium for distribution line |
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| US7714587B2 (en) * | 2007-06-29 | 2010-05-11 | Caterpillar Inc. | Systems and methods for detecting a faulty ground strap connection |
| CN101227089B (en) * | 2008-01-21 | 2011-04-13 | 孙嘉宁 | Discriminating and protecting method and apparatus for eliminating single phase ground fault by neutral point non-useful earthing electric network |
| CN102288875B (en) * | 2011-07-12 | 2013-06-12 | 国网电力科学研究院 | Low-current grounding wire-selecting method |
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