CN103197274A - Calibration system and calibration method of alternating large current of current transformer - Google Patents
Calibration system and calibration method of alternating large current of current transformer Download PDFInfo
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- CN103197274A CN103197274A CN2013100798002A CN201310079800A CN103197274A CN 103197274 A CN103197274 A CN 103197274A CN 2013100798002 A CN2013100798002 A CN 2013100798002A CN 201310079800 A CN201310079800 A CN 201310079800A CN 103197274 A CN103197274 A CN 103197274A
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Abstract
The invention discloses a calibration system and a calibration method of an alternating large current of a current transformer. The calibration system of the alternating large current of the current transformer comprises a large current sensing unit, a data collection unit and a personal computer (PC), wherein the large current sensing unit comprises an iron core coil, a hollow coil, a signal conditioning unit and a shielding case, the hollow coil and the signal conditioning unit are fixed inside the shielding case, the iron core coil, the hollow coil and the shielding case are respectively installed on a current-carrying wire, a first bypass wire is arranged between the iron coil and the hollow coil, and an output end of the signal conditioning unit is connected with the PC through the data collection unit. Mutual inductance coefficients of the installed hollow coil are calibrated through the iron core coil, whether a state of the hollow coil meets a calibration condition or not is judged, closed-loop control when calibration is conducted is finished through feedback of the mutual inductance coefficients of the hollow coil, the high-accuracy calibration on the alternating large current is achieved, and output accuracy of the current transformer with the hollow coil is ensured.
Description
Technical field
The present invention is specifically related to a kind of current transformer AC great current check system and method based on air core coil coefficient of mutual inductance self checking principle, belongs to the electrical energy parameter field of measuring technique.
Background technology
Fast development along with electric system, the electric pressure of electrical network improves constantly, electric current also constantly increases, but the performance of metering outfit is subjected to bigger test under high voltage, the big current conditions, as one of important metering outfit of transformer station, performance and the verification thereof of current transformer under big current conditions is subjected to increasing attention.
The general calibration equipment that adopts based on electromagnetic transformer of traditional current transformer calibration equipment, can only be under little current conditions the performance of verification current transformer, electric current for tens of kA, because the saturation characteristic of iron core cause the accuracy of standard current transformer can't reach the verification requirement, even deviation is very big, if the coil of iron core will reach the precision that verification is used, volume can be very big, is unfavorable for processing, more is not suitable for execute-in-place.
At present, based on the current transformer of air core coil, have dynamic range big, measure advantages such as bandwidth, the linearity are good, the first-selection when becoming the AC great current measurement.Yet, because the output signal of air core coil is little, be subjected to the influence of external electromagnetic field and current carrying conductor position bigger, therefore its precision is not high, theoretical precision is up to 0.1%, yet do not reach theoretical precision in the reality far away, in order to improve measuring accuracy, some researchist adopts many forms to the series connection of PCB type air core coil, in order to improve the amplitude of output signal, (Granted publication number: just adopt this form CN 1967267A), the quantity of series coil depends on size and the permissible accuracy of primary current as patent; Also have patent (Granted publication number: CN 2099085Y) also be mentioned to current transformer based on air core coil, but above-mentioned patent has the following disadvantages:
1) air core coil is output as differential signal, need in subsequent conditioning circuit, add the hardware integrating circuit or in software, handle, the hardware integrating circuit can be subjected to the influence of temperature drift and time drift, the software integration can be subjected to the influence of flip-flop in the signal, therefore all can introduce additional error to signal, iron-core coil does not then need corresponding integrating circuit, and its output can directly be gathered through behind the resistance sampling, so ratio of precision air core coil height;
2) although the series connection of a plurality of air core coils can increase output signal, can increase the internal resistance of air core coil simultaneously, make output produce error;
3) measuring accuracy of air core coil is subjected to the influence of installation site very big, so during big electric current verification, under installation process and the uncontrollable prerequisite of result, the measuring accuracy of air core coil also is uncontrollable, be difficult to guarantee the current measurement precision of normalized current passage, to such an extent as to the confidence level of check results is under suspicion.
Summary of the invention
In order to overcome problems of the prior art, the present invention proposes current transformer AC great current check system and the method based on air core coil coefficient of mutual inductance self checking principle, utilize iron-core coil that the coefficient of mutual inductance that the back air core coil is installed is proofreaied and correct, judge whether the air core coil state satisfies the verification condition, and the feedback by the air core coil coefficient of mutual inductance, closed-loop control when finishing verification has realized high-precision AC great current verification, guarantees the output accuracy of hollow coil current transformer.
In order to achieve the above object, the technical solution adopted in the present invention is:
A kind of AC great current check system of current transformer, it is characterized in that: comprise big current sensing unit, data acquisition unit and PC, it is characterized in that: described big current sensing unit comprises iron-core coil, air core coil, signal condition unit and radome, described air core coil and signal condition unit are fixed on radome inside, described iron-core coil, air core coil and radome are installed on the current carrying conductor respectively, be provided with the first bypass lead between described iron-core coil and the air core coil, the end of the described first bypass lead is provided with the first input end that first splicing ear is big current sensing unit, the end of described current carrying conductor is provided with second input end that second splicing ear is big current sensing unit, and the output terminal of described signal condition unit is connected with PC by data acquisition unit as the signal output part of big current sensing unit.
The AC great current check system of aforesaid current transformer is characterized in that: described iron-core coil is that punching is fixed on the current carrying conductor.
The AC great current check system of aforesaid current transformer is characterized in that: the described first bypass lead is connected with current carrying conductor is vertical.
The AC great current check system of aforesaid current transformer is characterized in that: described data acquisition unit is data collecting card.
The AC great current check system of aforesaid current transformer is characterized in that: described current carrying conductor is the metallic hard lead.
The AC great current check system of aforesaid current transformer is characterized in that: described iron-core coil, air core coil and radome are installed in respectively on the current carrying conductor, and the distance between iron-core coil and the air core coil can be adjusted.
AC great current method of calibration based on above-mentioned current transformer is characterized in that: may further comprise the steps:
The coefficient of mutual inductance self checking stage of step (1) air core coil
By the first input end input of big current sensing unit, iron-core coil and air core coil all insert the verification loop, and iron-core coil and air core coil all insert in the loop, and the coefficient of mutual inductance of air core coil is proofreaied and correct;
Step (2) the AC great current verification stage
By second input end input of big current sensing unit, iron-core coil is removed the verification loop, have only this moment air core coil to insert the verification loop, calculate and verification carried out error by the big electric current of current transformer output AC of verification.
The AC great current method of calibration of aforesaid current transformer is characterized in that: the described step that the coefficient of mutual inductance of air core coil is proofreaied and correct of step (1) is as follows:
1) record iron-core coil output valve, with the output valve of iron-core coil as the standard value of proofreading and correct;
2) according to the calculated value that calculates of air core coil coefficient of mutual inductance, calculate both errors;
3) when error met corresponding class of accuracy regulation, the state of air core coil satisfied the conditional request of verification standard channel;
4) surpass the upper threshold of regulation when error, then adjust the spacing between iron-core coil and the air core coil, repeat 1 again after the adjustment)-2), satisfy the conditional request of verification standard channel until the state of air core coil.
The invention has the beneficial effects as follows: current transformer AC great current check system and method based on the verification of air core coil coefficient of mutual inductance that the present invention proposes, utilize iron-core coil that the coefficient of mutual inductance that the back air core coil is installed is proofreaied and correct, judge whether the air core coil state satisfies the verification condition, pass through the feedback of air core coil coefficient of mutual inductance then, closed-loop control when finishing verification, realize high-precision AC great current verification, guaranteed the output accuracy of hollow coil current transformer.
Description of drawings
Fig. 1 is the system chart of the AC great current check system of current transformer of the present invention.
Fig. 2 is the connection layout of air core coil coefficient of mutual inductance calibration phase of the present invention.
Fig. 3 is the connection layout in AC great current verification stage of the present invention.
The mark implication of accompanying drawing is as follows:
1: big current sensing unit; 2: data acquisition unit; The 3:PC machine; 4: iron-core coil; 5: air core coil; 6: the signal condition unit; 7: radome; 8: current carrying conductor; 9: the first bypass leads; 10: the first splicing ears; 11: the second splicing ears.
Embodiment
Below in conjunction with Figure of description, the present invention is further illustrated.
Current transformer AC great current check system and method based on the verification of air core coil coefficient of mutual inductance of the present invention, utilize iron-core coil that the coefficient of mutual inductance that the back air core coil is installed is proofreaied and correct, judge whether the air core coil state satisfies the verification condition, pass through the feedback of air core coil coefficient of mutual inductance then, closed-loop control when finishing verification, realized high-precision AC great current verification, guarantee the output accuracy of hollow coil current transformer, as shown in Figure 1, the AC great current check system of current transformer of the present invention, comprise big current sensing unit 1, data acquisition unit 2 and PC 3, big current sensing unit comprises iron-core coil 4, air core coil 5, signal condition unit 6 and radome 7, air core coil 5 and signal condition unit 6 are fixed on radome 7 inside, air core coil 5 and signal condition unit 6, size (the external diameter of radome 7, internal diameter, thickness) can actual conditions adjust.Iron-core coil 4, air core coil 5 and radome 6 are installed in respectively on the current carrying conductor 8, current carrying conductor 8 is the metallic hard lead, be provided with the first bypass lead 9 between iron-core coil 4 and the air core coil 5, the first bypass lead 9 is drawn from current carrying conductor 8 by bolt, and the distance between iron-core coil 4 and the air core coil 5 can be adjusted, the end of the first bypass lead 9 is provided with first splicing ear 10 and is the first input end of big current sensing unit 1, the end of current carrying conductor 8 is provided with second splicing ear 11 and is second input end of big current sensing unit 1, the output terminal of signal condition unit 6 is connected with PC 3 by data acquisition unit 2 as the signal output part of big current sensing unit 1, data acquisition unit 2 is data collecting card, PC 3 arranges accordingly by the data of gathering, prepare to measure and verification, wherein iron-core coil 4 is fixed on the current carrying conductor 1 for punching, the first bypass lead 9 and 8 vertical connections of current carrying conductor, to reduce the electromagnetic interference (EMI) to big current sensing unit 1, improve the accuracy of proofreading and correct, guarantee the output accuracy of hollow coil current transformer.
AC great current method of calibration based on above-mentioned current transformer is characterized in that: may further comprise the steps:
The first step, the coefficient of mutual inductance self checking stage of air core coil 5
By the first input end input of big current sensing unit 1, iron-core coil 4 and air core coil 5 all insert the verification loop, and iron-core coil 4 and air core coil 5 all insert in the loop, and the method that the coefficient of mutual inductance of air core coil 1 is proofreaied and correct is as follows:
1) output valve of record iron-core coil 4, with the output valve of iron-core coil 1 as the standard value of proofreading and correct;
2) according to the calculated value that calculates of the coefficient of mutual inductance of air core coil 5, calculate both errors;
3) when error met corresponding class of accuracy regulation, the state of air core coil 5 satisfied the conditional request of verification standard channel, and the class of accuracy here is no more than 0.05% for being generally;
4) surpass the upper threshold of regulation when error, then adjust the spacing between iron-core coil 4 and the air core coil 5, repeat 1 again after the adjustment)-2), satisfy the conditional request of verification standard channel until the state of air core coil 5.
Second step, the AC great current verification stage
By second input end input of big current sensing unit 1, iron-core coil 4 is removed the verification loop, have only this moment air core coil 5 to insert the verification loop, calculate and verification carried out error by the big electric current of current transformer output AC of verification.
In sum, AC great current check system level method based on the verification of air core coil coefficient of mutual inductance, according to iron-core coil and air core coil characteristic separately, be the accuracy height of iron-core coil when measuring little electric current, good stability, good these two characteristics of situation lower linear degree that air core coil is fixing in the installation site, in both common current measuring ranges, at first utilize iron-core coil that the coefficient of mutual inductance that the back air core coil is installed is proofreaied and correct, judge whether the air core coil state satisfies the verification condition, thereby realize the whether satisfactory judgement of hollow coil current-sensing device service condition, pass through the feedback of air core coil coefficient of mutual inductance then, closed-loop control when finishing verification has realized high-precision AC great current verification.
More than show and described ultimate principle of the present invention, principal character and advantage.The technician of the industry should understand; the present invention is not restricted to the described embodiments; that describes in above-described embodiment and the instructions just illustrates principle of the present invention; without departing from the spirit and scope of the present invention; the present invention also has various changes and modifications, and these changes and improvements all fall in the claimed scope of the invention.The claimed scope of the present invention is defined by appending claims and equivalent thereof.
Claims (8)
1. the AC great current check system of current transformer, it is characterized in that: comprise big current sensing unit, data acquisition unit and PC, it is characterized in that: described big current sensing unit comprises iron-core coil, air core coil, signal condition unit and radome, described air core coil and signal condition unit are fixed on radome inside, described iron-core coil, air core coil and radome are installed on the current carrying conductor respectively, be provided with the first bypass lead between described iron-core coil and the air core coil, the end of the described first bypass lead is provided with the first input end that first splicing ear is big current sensing unit, the end of described current carrying conductor is provided with second input end that second splicing ear is big current sensing unit, and the output terminal of described signal condition unit is connected with PC by data acquisition unit as the signal output part of big current sensing unit.
2. the AC great current check system of current transformer according to claim 1, it is characterized in that: described iron-core coil is that punching is fixed on the current carrying conductor.
3. the AC great current check system of current transformer according to claim 1, it is characterized in that: the described first bypass lead is connected with current carrying conductor is vertical.
4. the AC great current check system of current transformer according to claim 1, it is characterized in that: described data acquisition unit is data collecting card.
5. the AC great current check system of current transformer according to claim 1 and 2, it is characterized in that: described current carrying conductor is the metallic hard lead.
6. the AC great current check system of current transformer according to claim 1, it is characterized in that: described iron-core coil, air core coil and radome are installed in respectively on the current carrying conductor, and the distance between iron-core coil and the air core coil can be adjusted.
7. based on the AC great current method of calibration of the described current transformer of claim 1, it is characterized in that: may further comprise the steps:
The coefficient of mutual inductance self checking stage of step (1) air core coil
By the first input end input of big current sensing unit, iron-core coil and air core coil all insert the verification loop, and iron-core coil and air core coil all insert in the loop, and the coefficient of mutual inductance of air core coil is proofreaied and correct;
Step (2) the AC great current verification stage
By second input end input of big current sensing unit, iron-core coil is removed the verification loop, have only this moment air core coil to insert the verification loop, calculate and verification carried out error by the big electric current of current transformer output AC of verification.
8. the AC great current method of calibration of current transformer according to claim 7, it is characterized in that: the described step that the coefficient of mutual inductance of air core coil is proofreaied and correct of step (1) is as follows:
1) output valve of record iron-core coil, with the output valve of iron-core coil as the standard value of proofreading and correct;
2) according to the calculated value that calculates of air core coil coefficient of mutual inductance, calculate both errors;
3) when error met corresponding class of accuracy regulation, the state of air core coil satisfied the conditional request of verification standard channel;
4) surpass the upper threshold of regulation when error, then adjust the spacing between iron-core coil and the air core coil, repeat 1 again after the adjustment)-2), satisfy the conditional request of verification standard channel until the state of air core coil.
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Cited By (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014194514A1 (en) * | 2013-06-07 | 2014-12-11 | 国家电网公司 | Heavy ac current calibration system based on self-calibration principle of coefficient of mutual induction of hollow coil |
| CN104730479A (en) * | 2013-12-18 | 2015-06-24 | 比亚迪股份有限公司 | Current sensor detection device and method |
| CN105510679A (en) * | 2016-01-21 | 2016-04-20 | 江苏省电力公司电力科学研究院 | High-reliability and high-precision current measuring method and device |
| CN106093511A (en) * | 2016-08-26 | 2016-11-09 | 三峡大学 | A kind of iron-core coil high-precision electronic insertion current transformer containing air gap |
| CN108802445A (en) * | 2017-03-13 | 2018-11-13 | 贵州电网有限责任公司电力科学研究院 | A kind of program controled power source and method of intelligent grid digitizer qualification |
| CN110310808A (en) * | 2019-07-09 | 2019-10-08 | 威胜电气有限公司 | A kind of current transformer and breaker |
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2014194514A1 (en) * | 2013-06-07 | 2014-12-11 | 国家电网公司 | Heavy ac current calibration system based on self-calibration principle of coefficient of mutual induction of hollow coil |
| CN104730479A (en) * | 2013-12-18 | 2015-06-24 | 比亚迪股份有限公司 | Current sensor detection device and method |
| CN105510679A (en) * | 2016-01-21 | 2016-04-20 | 江苏省电力公司电力科学研究院 | High-reliability and high-precision current measuring method and device |
| CN106093511A (en) * | 2016-08-26 | 2016-11-09 | 三峡大学 | A kind of iron-core coil high-precision electronic insertion current transformer containing air gap |
| CN106093511B (en) * | 2016-08-26 | 2023-10-27 | 三峡大学 | High-precision electronic current transformer with iron core coil containing air gap |
| CN108802445A (en) * | 2017-03-13 | 2018-11-13 | 贵州电网有限责任公司电力科学研究院 | A kind of program controled power source and method of intelligent grid digitizer qualification |
| CN110310808A (en) * | 2019-07-09 | 2019-10-08 | 威胜电气有限公司 | A kind of current transformer and breaker |
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| CN103197274B (en) | 2014-07-16 |
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