CN206387901U - CVT error in dipping anomaly assessment systems based on capacitive earth current - Google Patents
CVT error in dipping anomaly assessment systems based on capacitive earth current Download PDFInfo
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- CN206387901U CN206387901U CN201720097362.6U CN201720097362U CN206387901U CN 206387901 U CN206387901 U CN 206387901U CN 201720097362 U CN201720097362 U CN 201720097362U CN 206387901 U CN206387901 U CN 206387901U
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Abstract
The application discloses a kind of CVT error in dipping anomaly assessment systems based on capacitive earth current in fact, and the three-phase CVT capacitive earth current L (i in circuit to be measured are gathered in real timeA(t), iB(t), iC(t))；According to L (iA(t), iB(t), iC(t)), calculate the power frequency component L (i of the three-phase CVT capacitive earth currents in circuit to be measuredDA, iDB, iDC)；Judge in preset time t, iDA、iDBWith iDCWhether default current threshold i is exceededD；If iDA、iDBWith iDCNot less than default current threshold iD, then judge that CVT error in dippings are normal；If iDA、iDBOr iDCMore than predetermined current threshold iD, then i is calculated respectivelyDA、iDB、iDCWith iDDifference；Judge Δ iDA、ΔiDB、ΔiDCIt is whether equal, if equal, judge that CVT error in dippings are normal；If unequal, judge that CVT error in dippings are abnormal.The application passes through the CVT error in dipping anomaly assessment system on-line measurement CVT capacitive earth currents based on capacitive earth current, realize the real-time monitoring to CVT error in dipping states, find that CVT error in dippings are abnormal in time, with reduce because error in dipping extremely caused by loss.
Description
Technical field
The application is related to the technical field of metering voltage transformer, more particularly to a kind of based on capacitive earth current
CVT error in dipping anomaly assessment systems.
Background technology
CVT (Capacitor Voltage Transformer, capacitance type potential transformer) is a kind of voltage conversion dress
Put, for being connected across between high pressure and zero line, high voltage is converted into the operating voltage of all kinds of instrument.CVT major function bag
Include：It is that measuring instrumentss and protective relaying device are powered, metering clearing, in line failure, valuable in protection circuit sets
Standby, motor and transformer, or coupled capacitor device is also served as high frequency carrier communication.Wherein, one as CVT is settled accounts in metering
Important use, electric energy, voltage or power for metering line.
In CVT metering settlement process, inevitably there is error in dipping, in order to ensure CVT error in dipping is being permitted
Perhaps in the range of, JJG1021-2007 vertification regulations are required, after in-site installation CVT, it is necessary to carry out error in dipping to it and examine and determine first,
CVT error in dipping can put into operation in the error range of setting.Meanwhile, the code it further provides that, CVT re-testing periods are not
Must be more than 4 years, to ensure metering accuracies of the CVT in During Process of Long-term Operation.
In the prior art, the CVT re-testing periods are longer (general 3-4), also, with the extension of CVT service lives, CVT
Easily it is damaged or aging.In the case where not examining and determine CVT, the typically more difficult discovery CVT error in dippings of staff
It is abnormal.If being continuing with the CVT of damage or aging, it will influence to measure the accuracy of settlement data, and then in the clearing that affect trade
Fairness.
Utility model content
This application provides the CVT error in dipping anomaly assessment systems based on capacitive earth current, to solve traditional CVT
Calibrating installation can not constantly examine and determine CVT error in dipping states, lead to not find that CVT error in dippings are abnormal in time, so as to influence
The problem of metering accuracy and fairness.
Present invention also provides a kind of CVT error in dipping anomaly assessment systems based on capacitive earth current, described device
Including the capacitive earth current acquisition module, the judge module of power frequency component computing module first, difference calculating module being sequentially connected
And second judge module；
The capacitive earth current acquisition module is used to gather the three-phase CVT capacitive earth currents L in circuit to be measured in real time
(iA(t), iB(t), iC(t))；
The power frequency component computing module is used for the power frequency component for calculating the three-phase CVT capacitive earth currents in circuit to be measured
L(iDA, iDB, iDC)；
First judge module is used to judge the i in preset time tDA、iDBWith iDCWhether default current threshold is exceeded
iD；
The difference calculating module is used to calculate iDA、iDB、iDCWith iDMathematic interpolation obtained by difference be denoted as Δ i respectivelyDA、
ΔiDBWith Δ iDC；
Second judge module is used to judge Δ iDA、ΔiDBWith Δ iDCIt is whether equal；
The system also includes error state output module, and the error state output module is used to export CVT metering mistakes
Difference is often or CVT error in dippings are normal.
Preferably, the power frequency component computing module is included in fast fourier transform algorithm submodule, quick Fu
Leaf transformation algorithm submodule uses the three-phase CVT capacitive earth currents in fast fourier transform algorithm, calculating circuit to be measured
Power frequency component.
Preferably, the system also includes the Image Rendering module being connected with power frequency component computing module, Image Rendering mould
Block is used for the power frequency component L (i according to CVT capacitive earth currentsDA, iDB, iDC), draw the power frequency component of CVT capacitive earth currents
L(iDA, iDB, iDC) image that changes over time.
Brief description of the drawings
In order to illustrate more clearly of the technical scheme of the application, letter will be made to the required accompanying drawing used in embodiment below
Singly introduce, it should be apparent that, for those of ordinary skills, without having to pay creative labor,
Other accompanying drawings can also be obtained according to these accompanying drawings.
Fig. 1 is CVT structural representations；
Fig. 2 is the structure of the CVT error in dipping anomaly assessment system one embodiment of the application based on capacitive earth current
Figure；
Fig. 3 is the workflow diagram of the CVT error in dipping anomaly assessment systems based on capacitive earth current；
Symbol in Fig. 1-3 is expressed as：1- capacitive earth current acquisition modules, 2- power frequency component computing modules, 21- is quick
Fourier Transform Algorithm submodule, the judge modules of 3- first, the judge modules of 4- second, 5- difference calculating modules, 6- error states
Output module, 7- Image Rendering modules.
Embodiment
Fig. 1 is CVT structural representations, as shown in figure 1, CVT includes capacitance partial pressure unit and electromagnetic unit, capacitance partial pressure list
Member includes the high-voltage capacitance CH and middle voltage capacitance CM of series connection；Electromagnetic unit includes intermediate transformer T, compensation reactor L, pressure limiting dress
Put F and damper D etc..After CVT switches on power, an electric field is produced between CVT power transmission line and the earth, power transmission line passes through big
Gas to ground discharge, the now discharge current on power transmission line be capacitive earth current.
Capacitive earth current it is small big relevant only with the capacitance of capacitance partial pressure unit, therefore, direct-to-ground capacitance electricity can be passed through
The measured value of stream assesses the state of CVT error in dippings.Meanwhile, on-line monitoring capacitive earth current is not interfering with power system just
Often operation, therefore, can online, capacitive earth current is measured in real time, so as to realize the real-time prison to the state of CVT error in dippings
Control.
Fig. 2 is the structure of the CVT error in dipping anomaly assessment system one embodiment of the application based on capacitive earth current
Figure, as shown in Fig. 2 the system includes capacitive earth current acquisition module 1, the power frequency component computing module 2, first being sequentially connected
Judge module 3, the judge module 4 of difference calculating module 5 and second.In order to show assessment result, the system also includes error state
Output module 6.
The input of the connection power frequency component of capacitive earth current acquisition module 1 computing module 2, capacitive earth current collection mould
Block gathers the three-phase CVT capacitive earth current L (i in circuit to be measured in real timeA(t), iB(t), iC(t)), and by the direct-to-ground capacitance of collection
Electric current L (iA(t), iB(t), iC(t)) it is sent to power frequency component computing module.
The output end of power frequency component computing module 2 connects the input of the first judge module 3, power frequency component computing module meter
Calculate the power frequency component L (i of the three-phase CVT capacitive earth currents in circuit to be measuredDA, iDB, iDC), and the direct-to-ground capacitance of calculating is electric
Power frequency component L (the i of streamDA, iDB, iDC) it is sent to the first judge module 3.In the present embodiment, power frequency component computing module 2 includes
Fast fourier transform algorithm submodule 21, the fast fourier transform algorithm submodule 21 is used to become using fast Fourier
Scaling method, calculates the power frequency component of the three-phase CVT capacitive earth currents in circuit to be measured.
First output end of the first judge module 3 connects the input of difference calculating module 5, and the of the first judge module 3
Two output ends connection error state output module 6.
CVT actual motions excessively in, because system or external interference cause iDA、iDBOr iDCFluctuate, or even cause
iDA、iDBOr iDCExceed default current threshold i within moment or short timeD.After interference is eliminated, iDA、iDBOr iDCIt will return
In the current range normally run.Therefore, in order to avoid because ground capacitance current is in short-term beyond iDAnd false judgment CVT error in dippings
In abnormal generation, the application, the first judge module 3 judges iDA、iDBWith iDCWhether it is continued above in preset time t default
Current threshold iD, and it will determine that result is sent to error state output module 6, or by the power frequency component L of capacitive earth current
(iDA, iDB, iDC) it is sent to difference calculating module 5.In actual application, those skilled in the art can be according to actual conditions
Preset time t is set, such as 30s, 45s or 60s.
The defeated place end of difference calculating module 5 connects the input of the second judge module 4, and difference calculating module 5 calculates iDA、
iDB、iDCWith iDDifference, calculate gained difference be denoted as Δ i respectivelyDA、ΔiDBWith Δ iDC, and by the Δ i of calculatingDA、ΔiDBWith Δ
iDCIt is sent to the second judge module 4.
The output end connection error state output module 6 of second judge module 4, the second judge module 4 is according to mathematic interpolation
The Δ i of module transmissionDA、ΔiDBWith Δ iDC, judge Δ iDA、ΔiDBWith Δ iDCIt is whether equal, and will determine that result is sent to mistake
Poor state output module 6.
The judged result that error state output module 6 is transmitted according to the first judge module 3 and the second judge module 4, accordingly
Export CVT error in dippings exception or CVT error in dippings are normal.
For the ease of checking the variation tendency of capacitive earth current, the system also includes Image Rendering module 7, Image Rendering
Module 7 is connected with power frequency component computing module 2, and Image Rendering module 7 is according to the power frequency component L (i of CVT capacitive earth currentsDA,
iDB, iDC), draw the power frequency component L (i of CVT capacitive earth currentsDA, iDB, iDC) image that changes over time.
Fig. 3 is the workflow diagram of the CVT error in dipping anomaly assessment systems based on capacitive earth current, as shown in figure 3,
Its course of work comprises the following steps：
S101, gathers the three-phase CVT capacitive earth currents in circuit to be measured, is denoted as L (i in real timeA(t), iB(t), iC(t))。
Certainly, a power system includes multiple CVT, in order to carry out monitoring to multiple CVT simultaneously, will gather each CVT
The three-phase CVT capacitive earth currents of place circuit, are denoted as Ln(iA(t), iB(t), iC(t)), wherein, n=1,2,3 ....Below will
By taking CVT monitoring process as an example.
S102, according to L (iA(t), iB(t), iC(t)), calculate the power frequency point of the three-phase CVT capacitive earth currents in circuit to be measured
Amount, is denoted as L (iDA, iDB, iDC)。
, will be according to collection in order to reduce in the fluctuation and interference that harmonic wave is caused to CVT capacitive earth current sizes, the application
Circuit to be measured in three-phase CVT capacitive earth current L (iA(t), iB(t), iC(t)), calculate the power frequency component L of capacitive earth current
(iDA, iDB, iDC).Wherein, in China's alternating current parameter standard, power frequency refers to 50Hz frequency, therefore, and power frequency component refers to
The size containing 50Hz compositions in the electric current (voltage) of alternating current.
Calculating the method for the power frequency component of capacitive earth current has a variety of, and such as least square method, it belongs to this Shen
Protection domain please.In the application, the three-phase CVT direct-to-ground capacitance electricity in circuit to be measured is calculated using fast fourier transform algorithm
The power frequency component of stream.
Also include during the variation tendency of CVT capacitive earth currents, CVT error in dipping anomaly assessments for the ease of checking
S110, draws the power frequency component L (i of CVT capacitive earth currentsDA, iDB, iDC) image that changes over time, the image using the time as
Transverse axis, with the electric current power frequency component L (i of CVT capacitive earth currentsDA, iDB, iDC) it is the longitudinal axis.By the image, CVT can be obtained and appointed
Anticipate the moment capacitive earth current size, and capacitive earth current variation tendency and duration.
S103, judges in preset time t, iDA、iDBWith iDCWhether default current threshold i is exceededD, wherein current threshold
Value iDThe maximum fluctuation scope allowed for capacitive earth current.Those skilled in the art can be according to actual conditions, predetermined current threshold
Value iDSize, its concrete numerical value is not defined herein.
CVT actual motions excessively in, because system or external interference cause iDA、iDBOr iDCFluctuate, or even cause
iDA、iDBOr iDCExceed default current threshold i within moment or short timeD.After interference is eliminated, iDA、iDBOr iDCIt will return
In the current range normally run.Therefore, in order to avoid because ground capacitance current is in short-term beyond iDAnd false judgment CVT error in dippings
In abnormal generation, the application, i is judgedDA、iDBWith iDCWhether default current threshold i is continued above in preset time tD。
If in preset time t, iDA、iDBWith iDCNot less than default current threshold iD, then CVT error in dippings are judged
Normal condition.
If in preset time t, iDA、iDBOr iDCExceed default current threshold i for a long timeD, then need to iDA、iDBWith iDC
Further calculated, to exclude because of the phenomenon that system fluctuation causes capacitive earth current to rise overally or decline.
S104, calculates i respectivelyDA、iDB、iDCWith iDDifference, calculate gained difference be denoted as Δ i respectivelyDA、ΔiDBWith Δ
iDC。
S105, judges Δ iDA、ΔiDB、ΔiDCIt is whether equal, if Δ iDA、ΔiDBWith Δ iDCIt is equal, then judge CVT meterings
Error normal condition.It is specifically included, if Δ iDA、ΔiDB、ΔiDCIt is equal or approximate, illustrate three-phase ground capacitance electric current iDA、
iDB、iDCThe increase or reduction of equal extent are occurred in that, now, it is believed that cause three-phase ground capacitance electric current iDA、iDB、iDCChange
The reason for be system fluctuation or external interference, rather than CVT causes, and therefore, judges that CVT error in dippings are normal.
S106, if Δ iDA、ΔiDBWith Δ iDCIt is unequal, then judge that CVT error in dippings are abnormal.
If Δ iDA、ΔiDBWith Δ iDCIt is unequal, illustrate three-phase ground capacitance electric current iDA、iDB、iDCOccur in various degree
Change, and curent change is lasting.Now, it can determine that and cause three-phase ground capacitance electric current iDA、iDBOr iDCThe reason for change is
CVT, therefore, judges that CVT error in dippings are abnormal.
In the application, the three-phase CVT capacitive earth currents in circuit to be measured are monitored in real time, can timely find that CVT is measured
Error is abnormal, once judging that CVT error in dippings are abnormal, staff will stop CVT gage work, and it is examined comprehensively
Look into, with reduce because error in dipping extremely caused by loss.
Claims (3)
1. a kind of CVT error in dipping anomaly assessment systems based on capacitive earth current, it is characterised in that including what is be sequentially connected
Capacitive earth current acquisition module (1), the judge module (3) of power frequency component computing module (2) first, difference calculating module (5) and
Second judge module (4)；
The capacitive earth current acquisition module (1) is used to gather the three-phase CVT capacitive earth currents L in circuit to be measured in real time
(iA(t), iB(t), iC(t))；
The power frequency component computing module (2) is used for the power frequency component L for calculating the three-phase CVT capacitive earth currents in circuit to be measured
(iDA, iDB, iDC)；
First judge module (3) is used to judge the i in preset time tDA、iDBWith iDCWhether default current threshold is exceeded
iD；
The difference calculating module (5) is used to calculate iDA、iDB、iDCWith iDMathematic interpolation obtained by difference be denoted as Δ i respectivelyDA、Δ
iDBWith Δ iDC；
Second judge module (4) is used to judge Δ iDA、ΔiDBWith Δ iDCIt is whether equal；
The system also includes error state output module (6), and the error state output module (6) is used to export CVT meterings
Error exception or CVT error in dippings are normal.
2. the system as claimed in claim 1, it is characterised in that the power frequency component computing module (2) includes fast Fourier
Algorithm submodule (21) is converted, the fast fourier transform algorithm submodule (21) uses fast fourier transform algorithm, counted
Calculate the power frequency component of the three-phase CVT capacitive earth currents in circuit to be measured.
3. the system as claimed in claim 1, it is characterised in that the system is also included with power frequency component computing module (2) even
The Image Rendering module (7) connect, described image drafting module (7) is used for the power frequency component L (i according to CVT capacitive earth currentsDA,
iDB, iDC), draw the power frequency component L (i of CVT capacitive earth currentsDA, iDB, iDC) image that changes over time.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106772200A (en) * | 2017-01-25 | 2017-05-31 | 云南电网有限责任公司电力科学研究院 | CVT error in dipping anomaly assessment method and system based on capacitive earth current |
| CN110689252A (en) * | 2019-09-20 | 2020-01-14 | 云南电网有限责任公司电力科学研究院 | Capacitive voltage transformer metering error situation sensing system |
-
2017
- 2017-01-25 CN CN201720097362.6U patent/CN206387901U/en not_active Withdrawn - After Issue
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106772200A (en) * | 2017-01-25 | 2017-05-31 | 云南电网有限责任公司电力科学研究院 | CVT error in dipping anomaly assessment method and system based on capacitive earth current |
| CN106772200B (en) * | 2017-01-25 | 2023-07-21 | 云南电网有限责任公司电力科学研究院 | CVT metering error abnormity evaluation method and system based on capacitance-to-ground current |
| CN110689252A (en) * | 2019-09-20 | 2020-01-14 | 云南电网有限责任公司电力科学研究院 | Capacitive voltage transformer metering error situation sensing system |
| CN110689252B (en) * | 2019-09-20 | 2023-07-18 | 云南电网有限责任公司电力科学研究院 | Capacitive voltage transformer metering error situation awareness system |
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