CN104049140A - Zero-sequence fault current sudden-change used small-current grounding fault starting method - Google Patents
Zero-sequence fault current sudden-change used small-current grounding fault starting method Download PDFInfo
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- CN104049140A CN104049140A CN201410297198.4A CN201410297198A CN104049140A CN 104049140 A CN104049140 A CN 104049140A CN 201410297198 A CN201410297198 A CN 201410297198A CN 104049140 A CN104049140 A CN 104049140A
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Abstract
The invention relates to a zero-sequence fault current sudden-change used small-current grounding fault starting method which includes the steps that zero-sequence current signals serve as starting signals of a device, the zero-sequence current signals in a system are sampled through the site device, and sampled signals are compared with a starting threshold value of the device to judge whether starting conditions of the device are met or not; when amplitudes of n of m continuous sampling points in all sampling points of a sampling window are larger than the starting threshold value of the device, the device is started, and fault data are recorded; otherwise, the device is not started, and the zero-sequence current signals in the system are continuously sampled. According to the zero-sequence fault current sudden-change used small-current grounding fault starting method, the site adaptability is high, and the starting sensitivity of the device is improved.
Description
Technical field
The present invention relates to field device start-up technique field, particularly a kind of low current grounding starting method that utilizes zero-sequence fault current break.
Background technology
The enabling signal of field device has residual voltage, three-phase voltage or zero-sequence current at present, whether the sampled point amplitude by contrast enabling signal decides device to start with startup threshold value, but enabling signal and entry condition that device starts are not quite similar, may cause device in the situation that hardware condition is very nearly the same, in work efficiency and accuracy, have larger gap.
Existing device starting method: device is all the time in the state to enabling signal (residual voltage, three-phase voltage or zero-sequence current) sampling, the amplitude of sampled signal and device are started to threshold value to be compared, if meet the entry condition that device is set, device starts and starts record trouble data, otherwise, device does not start, and continues enabling signal to sample.Although utilize residual voltage or three-phase voltage starting in reliability higher than the starting method that utilizes electric current as enabling signal as the starting method of enabling signal, but it is lower that it starts sensitivity, can make to a certain extent the startup that device cannot be promptly and accurately, cause missing some failure messages; In addition, be subject to the restriction of field condition, on-the-spot possibly cannot obtain voltage starting signal, can only utilize electric current as the enabling signal of device.Even if current signal can be used as the enabling signal of all devices, but the difference of its entry condition also can make the work efficiency of device and work accuracy have larger difference, the method just starting when having sampled point amplitude to be greater than threshold value cannot overcome the interference of extraneous factor to device, causes device frequent starting; The method just starting while having the amplitude of at least two continuous sampling points to be greater than threshold value in continuous three sampled points cannot adapt to the higher situation of field failure transient signal resonance frequency, will cause device tripping, work efficiency that cannot assurance device and work accuracy, miss some failure messages.
Summary of the invention
The object of the present invention is to provide a kind of low current grounding starting method that utilizes zero-sequence fault current break, the method is on-the-spot strong adaptability not only, and has improved the sensitivity that device starts.
For achieving the above object, technical scheme of the present invention is: a kind of low current grounding starting method that utilizes zero-sequence fault current break, utilize zero sequence current signal as the enabling signal of device, field device is sampled to the zero-sequence current in system, contrast sampled signal determines whether with the threshold value that device starts the entry condition that meets device: when all sampled points of sample window exist the situation of the threshold value that has the amplitude of n sampled point to be greater than device startup in a continuous m sampled point, device starts, record trouble data; Otherwise device does not start, continue the zero sequence current signal in system to sample.
The described low current grounding starting method that utilizes zero-sequence fault current break, comprises the following steps:
Step S1: the threshold value that field device starts is set
i st ; Threshold value
i st be set as:
I st ?=?
K rel I 0
i
In formula,
k rel for reliability coefficient;
i 0
i the effective value of check point i downstream circuit capacitive earth current, wherein:
I 0
i ?=?3
ωU 0
i C 0
i
In formula,
u 0
i it is the effective value of the residual voltage of check point i;
c 0
i it is the ground capacitance of check point i downstream circuit;
Step S2: device is sampled to the zero mould current signal of the transient state in system;
Step S3: sampled signal is compared with the threshold value that device starts, determine whether the entry condition that meets device:
Zero-sequence current sampled signal in sample window is compared with the threshold value that device starts, have the amplitude of at least two sampled points to be greater than the situation of the threshold value of device startup if exist in continuous three sampled points, device starts, and records field failure data; Otherwise device does not start, continue the zero sequence current signal in system to sample;
Step S4: field device records on-the-spot failure message, to carry out next step processing and computing after starting.
The invention has the beneficial effects as follows to have solved and utilize voltage to start the lower problem of sensitivity as enabling signal device, greatly improved the sensitivity that device starts, record trouble information that can be comparatively complete.Simultaneously, the present invention utilizes current signal as the starting method of enabling signal with respect to other, improved the antijamming capability of device, minimizing is because disturbing the device frequent starting causing in scene, also adapt to the higher situation of on-the-spot transient signal resonance frequency simultaneously, alleviate the communication pressure of field device, startup that can be accurate, in good time, has improved it to the adaptability of high frequency transient signal, work efficiency and work accuracy.
Accompanying drawing explanation
Fig. 1 is the realization flow figure of the embodiment of the present invention.
Fig. 2 has the amplitude of two sampled points to be greater than the schematic diagram of threshold value in continuous three sampled points in the embodiment of the present invention.
Embodiment
The present invention utilizes the low current grounding starting method of zero-sequence fault current break, utilize zero sequence current signal as the enabling signal of device, field device is sampled to the zero-sequence current in system, contrast sampled signal determines whether with the threshold value that device starts the entry condition that meets device: when all sampled points of sample window exist the situation of the threshold value that has the amplitude of two sampled points to be greater than device startup in continuous three sampled points, device starts, record trouble data; Otherwise device does not start, continue the zero sequence current signal in system to sample.
As shown in Figure 1, the described low current grounding starting method that utilizes zero-sequence fault current break, specifically comprises the following steps:
Step S1: the threshold value that field device starts is set
i st .Threshold value
i st be set as:
I st ?=?
K rel I 0
i
In formula,
k rel for reliability coefficient;
i 0
i the effective value of check point i downstream circuit capacitive earth current, wherein:
I 0
i ?=?3
ωU 0
i C 0
i
In formula,
u 0
i it is the effective value of the residual voltage of check point i;
c 0
i it is the ground capacitance of check point i downstream circuit.
Step S2: device is sampled to the zero mould current signal of the transient state in system.
The sampling module of field device is in the state to the sampling of system zero mould current signal always, and the follow-up threshold value by its amplitude and device startup compares, and judges whether to meet device entry condition.
Step S3: sampled signal is compared with the threshold value that device starts, determine whether the entry condition that meets device:
Zero-sequence current sampled signal in sample window is compared with the threshold value that device starts, if exist, in continuous three sampled points, there is the amplitude of at least two sampled points to be greater than the situation of the threshold value of device startup, as shown in Figure 2, device starts, and records field failure data; Otherwise device does not start, continue the zero sequence current signal in system to sample.
Step S4: field device records on-the-spot failure message, to carry out next step processing and computing after starting.
In the present embodiment, field device contains sampling module, communication module, counter, sampling module comprises that sampling routine, sampled value and the device of field data start the comparison program of threshold value, when sampled signal does not reach the condition of device startup, device will continue the zero mould current signal of system to sample.
On-the-spot current signal obtains by current transformer, wherein zero-sequence current obtained directly and indirect two kinds of modes: direct mode is to obtain by zero sequence current mutual inductor; Indirect mode is to obtain after synthesizing by three-phase current.When system is normally moved, generally do not have zero-sequence component, the zero-sequence current that directly metering system obtains is exactly fault current.And under indirect metering system, due to TA error, unit simulation processing of circuit and the error of calculation etc., even if symmetrical at primary current, not there is not zero-sequence component in the situation that, be added the power frequency zero sequence value obtaining also non-vanishing by three phase components, this component is called unbalanced component.For the accuracy that guarantees that fault power frequency component is measured, indirectly, under metering system, need to reject by zero-sequence component Sudden Changing Rate method the impact of amount of unbalance.
Be more than preferred embodiment of the present invention, all changes of doing according to technical solution of the present invention, when the function producing does not exceed the scope of technical solution of the present invention, all belong to protection scope of the present invention.
Claims (2)
1. a low current grounding starting method that utilizes zero-sequence fault current break, it is characterized in that, utilize zero sequence current signal as the enabling signal of device, field device is sampled to the zero-sequence current in system, contrast sampled signal determines whether with the threshold value that device starts the entry condition that meets device: when all sampled points of sample window exist the situation of the threshold value that has the amplitude of n sampled point to be greater than device startup in a continuous m sampled point, device starts, record trouble data; Otherwise device does not start, continue the zero sequence current signal in system to sample.
2. a kind of low current grounding starting method that utilizes zero-sequence fault current break according to claim 1, is characterized in that, comprises the following steps:
Step S1: the threshold value that field device starts is set
i st ; Threshold value
i st be set as:
I st ?=?
K rel I 0
i
In formula,
k rel for reliability coefficient;
i 0
i the effective value of check point i downstream circuit capacitive earth current, wherein:
I 0
i ?=?3
ωU 0
i C 0
i
In formula,
u 0
i it is the effective value of the residual voltage of check point i;
c 0
i it is the ground capacitance of check point i downstream circuit;
Step S2: device is sampled to the zero mould current signal of the transient state in system;
Step S3: sampled signal is compared with the threshold value that device starts, determine whether the entry condition that meets device:
Zero-sequence current sampled signal in sample window is compared with the threshold value that device starts, have the amplitude of at least two sampled points to be greater than the situation of the threshold value of device startup if exist in continuous three sampled points, device starts, and records field failure data; Otherwise device does not start, continue the zero sequence current signal in system to sample;
Step S4: field device records on-the-spot failure message, to carry out next step processing and computing after starting.
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Cited By (7)
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| CN105005014A (en) * | 2015-07-07 | 2015-10-28 | 南京国电南自电网自动化有限公司 | Merging unit with protection current transformer output abnormity detection function |
| CN106443343A (en) * | 2016-09-30 | 2017-02-22 | 国网福建省电力有限公司 | Small-current grounding fault positioning method employing transient zero sequence current |
| CN107843803A (en) * | 2017-10-19 | 2018-03-27 | 成都汉度科技有限公司 | Fault Locating Method based on 10kV power distribution networks FTU |
| CN109188310A (en) * | 2018-11-07 | 2019-01-11 | 内蒙古电力(集团)有限责任公司乌海电业局 | The power module failure monitoring device and system and monitoring method of the electrical secondary system of switchgear |
| CN109980612A (en) * | 2019-02-27 | 2019-07-05 | 南京国电南自电网自动化有限公司 | A kind of method that line differential protection realizes weak feedback starting using zero-sequence fault component |
| CN110632441A (en) * | 2019-09-30 | 2019-12-31 | 攀钢集团西昌钢钒有限公司 | Method, device and equipment for judging ground fault |
| CN111007359A (en) * | 2019-12-26 | 2020-04-14 | 积成电子股份有限公司 | Power distribution network single-phase earth fault identification starting method and system |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN105005014A (en) * | 2015-07-07 | 2015-10-28 | 南京国电南自电网自动化有限公司 | Merging unit with protection current transformer output abnormity detection function |
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| CN107843803A (en) * | 2017-10-19 | 2018-03-27 | 成都汉度科技有限公司 | Fault Locating Method based on 10kV power distribution networks FTU |
| CN109188310A (en) * | 2018-11-07 | 2019-01-11 | 内蒙古电力(集团)有限责任公司乌海电业局 | The power module failure monitoring device and system and monitoring method of the electrical secondary system of switchgear |
| CN109980612A (en) * | 2019-02-27 | 2019-07-05 | 南京国电南自电网自动化有限公司 | A kind of method that line differential protection realizes weak feedback starting using zero-sequence fault component |
| CN110632441A (en) * | 2019-09-30 | 2019-12-31 | 攀钢集团西昌钢钒有限公司 | Method, device and equipment for judging ground fault |
| CN111007359A (en) * | 2019-12-26 | 2020-04-14 | 积成电子股份有限公司 | Power distribution network single-phase earth fault identification starting method and system |
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Application publication date: 20140917 |