CN115877307A - Residual magnetism overhauling method for 10kV-110kV current transformer - Google Patents
Residual magnetism overhauling method for 10kV-110kV current transformer Download PDFInfo
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- 230000005389 magnetism Effects 0.000 title claims abstract description 68
- 238000000034 method Methods 0.000 title claims abstract description 49
- 230000005347 demagnetization Effects 0.000 claims abstract description 63
- 238000007689 inspection Methods 0.000 claims abstract description 20
- 230000002159 abnormal effect Effects 0.000 claims abstract description 15
- 238000012423 maintenance Methods 0.000 claims description 64
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical group [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims description 21
- 238000004804 winding Methods 0.000 claims description 15
- 238000012360 testing method Methods 0.000 claims description 13
- 229910000976 Electrical steel Inorganic materials 0.000 claims description 3
- 229910045601 alloy Inorganic materials 0.000 claims description 3
- 239000000956 alloy Substances 0.000 claims description 3
- 239000011162 core material Substances 0.000 claims description 3
- 229910000889 permalloy Inorganic materials 0.000 claims description 3
- 230000009286 beneficial effect Effects 0.000 abstract description 2
- 238000011156 evaluation Methods 0.000 description 22
- 230000005291 magnetic effect Effects 0.000 description 13
- 230000033228 biological regulation Effects 0.000 description 4
- 230000007423 decrease Effects 0.000 description 4
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- 230000005381 magnetic domain Effects 0.000 description 2
- 230000005415 magnetization Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
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- 238000004458 analytical method Methods 0.000 description 1
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- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000003302 ferromagnetic material Substances 0.000 description 1
- 238000009472 formulation Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
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Abstract
A10 kV-110kV current transformer remanence overhauling method relates to the technical field of current transformer remanence, and the structure is as follows: the method comprises the steps of current transformer remanence overhauling work, current transformer state overhauling work and current transformer remanence online standard demagnetization, wherein the current transformer remanence overhauling work comprises A type overhauling, B type overhauling, C type overhauling and D type overhauling, the current transformer state overhauling work comprises a normal state, an attention state and an abnormal state, and the current transformer remanence demagnetization comprises open circuit demagnetization and closed circuit demagnetization. The invention has the beneficial effects that: the overhauling method is high in efficiency, the current transformer which normally operates originally cannot break down due to human reasons, and comprehensive inspection of the state of the current transformer can be achieved. The operation principle of online demagnetization is the same as that of closed demagnetization, so that the residual magnetism of the current transformer can be safely and effectively eliminated by utilizing the online demagnetization.
Description
Technical Field
The invention relates to the technical field of remanence of current transformers, in particular to a remanence overhauling method of a 10kV-110kV current transformer.
Background
At present, no complete maintenance scheme exists for the current transformers which are commonly used on 10kV, 35kV and 110kV lines, the complete maintenance scheme comprises residual magnetism maintenance of newly-put-into-operation current transformers and residual magnetism maintenance of old current transformers, the residual magnetism maintenance method of the current transformers is mainly aimed at residual magnetism of iron cores, the residual magnetism maintenance method is suitable for maintaining the current transformers which generate residual magnetism in the iron cores after short-circuit faults of an electric power system occur, the maintenance work of the current transformers is single generally according to the content and the related working range of the working property, the residual magnetism maintenance does not have the basis of residual magnetism evaluation results, and the dynamic maintenance plan and the content of arranging state maintenance are not made by considering risk factors.
In order to ensure that the current transformer can normally operate, the operating state of the current transformer needs to be remotely estimated, most of the existing current transformer state maintenance methods adopt a manual maintenance mode, the manual maintenance mode needs a large amount of manual work to carry out field inspection and a complex calculation process, and the working efficiency is low; the existing manual maintenance method of the current transformer only attaches importance to maintenance of accuracy and wiring correctness of the current transformer, comprehensive maintenance of the state of the current transformer cannot be realized, the finally obtained inspection result is inaccurate, manual intervention is easy to make mistakes, the reliability of the inspection result is low, the dynamic safety and stability of the current transformer cannot be accurately mastered, further, safety, stability and accurate operation of each main current transformer cannot be guaranteed, dynamic tracking and analysis on accident handling information are lacked, and dynamic control on serious faults cannot be carried out.
Disclosure of Invention
Aiming at the defects of the prior art, the invention provides a residual magnetism overhauling method of a 10kV-110kV current transformer, which aims to solve the problems.
The invention provides a residual magnetism overhauling method of a 10kV-110kV current transformer, which comprises the following steps: the method comprises the steps of current transformer remanence overhauling work, current transformer state overhauling work and current transformer remanence online standard demagnetization, wherein the current transformer remanence overhauling work and the current transformer state overhauling work are carried out simultaneously, the current transformer remanence overhauling work comprises type A overhauling, type B overhauling, type C overhauling and type D overhauling, the current transformer state overhauling work comprises a normal state, an attention state and an abnormal state, the current transformer remanence online standard demagnetization is carried out by utilizing alternating current demagnetization, the current transformer remanence online standard demagnetization comprises an open-circuit demagnetization method, a closed-circuit demagnetization method and online demagnetization, and the online demagnetization is carried out by secondary side short circuit.
Preferably, the residual magnetism overhauling work of the current transformer aims at the residual magnetism of an iron core, and the iron core material of the current transformer is silicon steel, or an ultra-microcrystalline alloy, or a permalloy.
Preferably, according to the content of the working property and the working related range, the overhauling work of the current transformer can be divided into four types: the method comprises the following steps of A type maintenance, B type maintenance, C type maintenance and D type maintenance, wherein the A type maintenance refers to the overall inspection, maintenance, part replacement and test of a current transformer body and is power failure maintenance; the B-type maintenance refers to local maintenance of the current transformer, disassembly inspection, maintenance, replacement, test and the like of a replacement part of the part, and is power failure maintenance; the class C overhauling refers to the conventional inspection, maintenance and test of the current transformer and is power-off overhauling; the D-type maintenance is the live test, appearance inspection and maintenance of the current transformer in a non-power-off state.
Preferably, the evaluation state refers to a result of evaluating the residual magnetism performance of the electromagnetic current transformer. For the residual magnetism performance evaluation of the current transformer, the evaluation state can be divided into three types of normal, attention and abnormal. And carrying out different types of overhauling operation on the current transformers in different residual magnetism evaluation states.
The residual magnetism in the iron core of the current transformer is small in the normal state, the current transformer can stably operate in a linear region, the metering error of the current transformer meets the regulation of the national standard, D-type maintenance is performed on the current transformer, and the residual magnetism maintenance working cycle of the current transformer in the normal state is a normal cycle; in the attention state, the residual magnetism in the iron core of the current transformer is relatively large, the magnetic flux variation range of the current transformer is in a linear region or a non-linear region, the metering error of the current transformer is determined according to the operation condition, C-type maintenance is carried out on the current transformer, and the residual magnetism maintenance work cycle of the current transformer in the state is not more than the normal cycle; the residual magnetism of the iron core of the current transformer is very large in the abnormal state, the current transformer operates in a nonlinear region, the metering error of the current transformer exceeds the regulation of the national standard, the electric quantity cannot be accurately metered, class B overhauling is performed on the current transformer, and the residual magnetism overhauling work of the current transformer in the abnormal state is required to be arranged as soon as possible.
Preferably, when the open-circuit demagnetization method is used, one winding with a smaller number of turns in the primary (or secondary) winding is selected to be electrified with 10% rated primary (or secondary) current, and the current is smoothly and slowly reduced to zero under the condition that other windings are all open-circuit; when the closed-circuit demagnetization method is used, a resistor which is 10-20 times of rated load is connected to the secondary winding, power frequency current is conducted to the primary winding, the current is increased from zero to 1.2 times of rated current, and then the current is uniformly and slowly reduced to zero.
The invention has the beneficial effects that: because the remanence overhaul work of the current transformer and the state overhaul work of the current transformer are carried out simultaneously, the overhaul strategy also comprises the formulation of a remanence overhaul plan, the maintenance and the inspection without power failure and the like. And the maintenance strategy should be dynamically adjusted according to the residual magnetism evaluation result of the current transformer.
And the residual magnetism maintenance work needs to consider the risk evaluation factors of the current transformer according to the latest residual magnetism dynamic evaluation result and consult the manufacturer opinion to determine the next power failure maintenance category, maintenance time and maintenance content. When the maintenance plan is arranged, the maintenance periods of the related equipment are coordinated, the maintenance periods are uniformly arranged as much as possible, and repeated power failure is avoided. The uninterrupted maintenance and test are arranged according to actual conditions. And establishing a corresponding maintenance strategy according to the residual magnetism evaluation result of the current transformer, wherein the maintenance strategy of the current transformer is determined according to the state of the residual magnetism evaluation.
The remanence overhaul follows the principle of 'must repair, must repair', and the maintenance plan is dynamically made according to the remanence evaluation result, considering the risk factors, and reasonably arranging the plan and the content of the state overhaul.
The overhauling method is high in efficiency, the current transformer which normally runs originally cannot break down due to human reasons, the overhauling method comprehensively considers basic information data, detection data, monitoring data and residual magnetism overhauling schemes of the current transformer, comprehensive overhauling of the state of the current transformer can be achieved, and the finally obtained overhauling result is accurate, comprehensive and high in reliability.
The operation principle of the online demagnetization 14 is the same as that of the closed demagnetization 13, the safety of the demagnetization process is ensured by using the short-circuit operation, and in order to ensure the safety and the effectiveness of the demagnetization operation, the adjustable rheostat connected with the secondary side 15 in series must be smoothly and continuously adjusted to ensure the continuous contact between the rheostat slide sheet and the resistor, so that the residual magnetism of the current transformer can be safely and effectively eliminated by using the online demagnetization 14.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic structural view of the present invention;
FIG. 2 is a wiring diagram for online demagnetization according to the present invention;
in the figure: 1. the method comprises the following steps of demagnetizing by utilizing alternating current, overhauling work of residual magnetism of a current transformer 2, overhauling work of state of the current transformer 3, online standard demagnetization of the residual magnetism of the current transformer 4, overhauling of class 5 and class A, overhauling of class 6 and class B, overhauling of class 7 and class C, overhauling of class 8 and class D, 9, normal state, 10 attention state, 11 abnormal state, 12, open-circuit demagnetization method, 13, closed-circuit demagnetization method, 14, online demagnetization, 15 and secondary side.
Detailed Description
Example 1
The invention provides a residual magnetism overhauling method of a 10kV-110kV current transformer, which comprises the following steps: the method comprises a current transformer remanence overhaul work 2, a current transformer state overhaul work 3 and a current transformer remanence online standard demagnetization 4, wherein the current transformer remanence overhaul work 2 and the current transformer state overhaul work 3 are carried out simultaneously, the current transformer remanence overhaul work 2 comprises an A type overhaul 5, a B type overhaul 6, a C type overhaul 7 and a D type overhaul 8, the current transformer state overhaul work 3 comprises a normal state 9, an attention state 10 and an abnormal state 11, the current transformer remanence online standard demagnetization 4 is carried out by utilizing an alternating current demagnetization 1, the current transformer remanence online standard demagnetization 4 comprises an open-circuit demagnetization method 12, a closed-circuit demagnetization method 13 and an online demagnetization 14, and the online demagnetization 14 is carried out by a secondary side 15 short circuit.
Preferably, the residual magnetism overhaul work 2 of the current transformer aims at the residual magnetism of an iron core, and the iron core material of the current transformer is silicon steel, or an ultra-microcrystalline alloy, or a permalloy.
Preferably, according to the content of the working property and the working related range, the overhauling work of the current transformer can be divided into four types: the system comprises a class A overhaul 5, a class B overhaul 6, a class C overhaul 7 and a class D overhaul 8, wherein the class A overhaul 5 refers to the overall inspection, maintenance, part replacement and test of a current transformer body and is power failure overhaul; the type B overhaul 6 refers to local overhaul of the current transformer, disassembly inspection, maintenance, replacement, test and the like of a replacement part of the part, and is power failure overhaul; the class C overhaul 7 is used for the conventional inspection, maintenance and test of the current transformer and is power failure overhaul; the D-type overhaul 8 is an electrified test, an appearance check and a maintenance which are carried out on the current transformer in a non-power-off state.
Preferably, the evaluation state refers to a result of evaluating the residual magnetism performance of the electromagnetic current transformer. For the evaluation of the residual magnetism performance of the current transformer, the evaluation state can be divided into three types, namely a normal state 9, an attention state 10 and an abnormal state 11. And carrying out different types of overhaul operation on the current transformers in different residual magnetism evaluation states.
The residual magnetism in the iron core of the current transformer is small in the normal state 9, the current transformer can stably operate in a linear region, the metering error of the current transformer meets the regulations of national standards, the residual magnetism evaluation work is required before the residual magnetism maintenance work of the current transformer is carried out, when the final result of the residual magnetism evaluation is in a normal state, the residual magnetism in the iron core of the current transformer is small at the moment, the metering error of the current transformer still meets the requirement of the measurement precision, therefore, the residual magnetism of the current transformer is not required to be demagnetized, the D-type maintenance 8 is carried out on the current transformer, and the residual magnetism maintenance work cycle of the current transformer in the state is a normal cycle.
In the attention state 10, the residual magnetism in the iron core of the current transformer is relatively large, the magnetic flux variation range of the current transformer is in a linear region or a nonlinear region, the metering error of the current transformer is determined according to the operation condition, when the final result of the residual magnetism evaluation of the current transformer is in the attention state, the fact that the large residual magnetism exists in the iron core at the moment is indicated, and the metering error of the current transformer may exceed the condition specified by the national standard according to the operation condition. Therefore, in order to ensure the metering accuracy of the current transformer, demagnetization treatment is carried out on the current transformer, in order to reduce the power failure time, an online demagnetization method is suitably used for carrying out C-type maintenance 7 on the current transformer, and the residual magnetism maintenance working period of the current transformer in the state is not more than the normal period;
the residual magnetism of the iron core of the current transformer is very large in the abnormal state 11, the current transformer operates in a nonlinear region, the metering error of the current transformer exceeds the regulations of national standards, and the electric quantity can not be accurately metered, when the final result of the residual magnetism evaluation of the current transformer is in an abnormal state, the fact that the very large residual magnetism exists in the iron core at the moment is indicated, and the metering error of the current transformer exceeds the requirements of the national standards, so that the current transformer needs to be demagnetized, in the actual operation, the evaluation result of the current transformer is not easy to reach the abnormal state, if the final result of the residual magnetism evaluation reaches the abnormal state, the short-circuit current is very large, the huge short-circuit current not only can form a large amount of residual magnetism in the iron core of the current transformer, but also can not influence the material structure and the magnetization characteristic of the current transformer, so that when the residual magnetism evaluation result of the current transformer is in the abnormal state, not only the demagnetization operation is needed, but also the voltammetry characteristic curve and the hysteresis curve are remeasured to determine whether the magnetization characteristic is changed, the class B overhaul of the current transformer is performed 6, and the class B overhaul work of the current transformer in the state should be arranged as soon as possible.
Preferably, the current transformer must overlap magnetic poles and decrease the magnetic field intensity when demagnetizing, if the ferromagnetic material must disturb the consistency of the magnetic domain arrangement, make the magnetic domain arrangement disorderly and not show magnetism to the outside, utilize alternating current to demagnetize, can reach the overlap of the magnetic poles automatically, and use direct current must change the direct current direction alternatively, and the way that the magnetic field intensity decreases is usually that the test piece gradually leaves the magnetic field or the magnetic field gradually leaves the test piece, control the current attenuation or step-down by stage by the power, when using alternating current to demagnetize, put the work piece in the alternating magnetic field, produce the hysteresis loop, when the amplitude of the alternating magnetic field gradually decreases, the track of the hysteresis loop is also smaller and smaller, when the magnetic field intensity decreases to zero, make the residual magnetism in the work piece approach to zero, the change of the direction and size of the current and magnetic field must "commutate and attenuate at the same time" when demagnetizing.
The demagnetization method in the current transformer standard mainly comprises an open-circuit demagnetization method 12 and a closed-circuit demagnetization method 13, when the open-circuit demagnetization method 12 is utilized, one winding with less turns is selected from primary (or secondary) windings and is electrified with 10% rated primary (or secondary) current, and under the condition that other windings are all open-circuit, the current is stably and slowly reduced to zero; when the closed-circuit demagnetization method 13 is used, a resistor which is 10-20 times of rated load is connected to the secondary winding, power frequency current is conducted to the primary winding, the rated current is increased from zero to 1.2 times, then the current is uniformly and slowly reduced to zero, and the closed-circuit demagnetization method 13 shows that the voltage of the current transformer can reach 24 times of rated voltage at most during demagnetization, and then the voltage can be slowly reduced to zero.
When the current transformer is operated online, the load current is lower than the rated current, and the load current is assumed to be 50% of the rated current, so according to the closed demagnetization method 13, 50 times of rated resistance needs to be connected in series on the secondary side 15 of the current transformer, and then the voltage is uniformly and slowly reduced to zero, if the rated load of the current transformer is 10 Ω, the resistance in series is 500 Ω, although the method of reducing the induced voltage by the closed demagnetization method 13 is to reduce the load current, the voltage can be reduced by gradually reducing the series resistance of the secondary side 15, so as to achieve the effect of decreasing the magnetic field strength, when the current transformer is actually operated, because of the existence of the load current, the secondary side 15 loop cannot be directly disconnected, and demagnetization is performed, therefore, in order to safely perform demagnetization, the secondary side 15 needs to be short-circuited, and then online demagnetization 14 is performed.
As shown in fig. 2, the online demagnetization 14 includes the following specific steps;
(1) Closing the manual switch to short-circuit the secondary side 15;
(2) Opening the original secondary side 15 line and connecting an adjustable rheostat in series;
(3) Opening the manual switch, and uniformly and slowly reducing the resistance value of the adjustable resistor to zero;
(4) Closing the manual switch, and withdrawing the adjustable rheostat from the original secondary side 15 circuit;
(5) And opening the manual switch, and finishing demagnetization of the current transformer.
Finally, it should be noted that: it should be understood that the above examples are only for clearly illustrating the present invention and are not intended to limit the embodiments. Other variations and modifications will be apparent to persons skilled in the art in light of the above description. And are neither required nor exhaustive of all embodiments. And obvious variations or modifications of the invention may be made without departing from the scope of the invention.
Claims (5)
1. A10 kV-110kV current transformer residual magnetism overhauling method is characterized by comprising the following steps: the current transformer remanence online standard demagnetization control method comprises current transformer remanence overhauling work (2), current transformer state overhauling work (3) and current transformer remanence online standard demagnetization (4), wherein the current transformer remanence overhauling work (2) and the current transformer state overhauling work (3) are carried out simultaneously, the current transformer remanence overhauling work (2) comprises A-type overhauling (5), B-type overhauling (6), C-type overhauling (7) and D-type overhauling (8), the current transformer state overhauling work (3) comprises a normal state (9), an attention state (10) and an abnormal state (11), the current transformer remanence online standard demagnetization (4) is carried out by utilizing alternating current demagnetization (1), the current transformer remanence online standard demagnetization (4) comprises an open-circuit demagnetization method (12), a closed-circuit demagnetization method (13) and online demagnetization (14), and the online demagnetization (14) is carried out through short circuit by a secondary side (15).
2. The residual magnetism overhauling method of the 10kV-110kV current transformer according to claim 1, characterized in that: the residual magnetism overhauling work (2) of the current transformer aims at iron core residual magnetism, and the iron core material of the current transformer is silicon steel, or ultra-microcrystalline alloy, or permalloy.
3. The residual magnetism overhauling method of the 10kV-110kV current transformer according to claim 1, characterized in that: the inspection and maintenance of the current transformer body integrity, the replacement and the test of parts are realized by the type A inspection (5), the inspection and maintenance of the current transformer body are realized by power failure, the inspection and maintenance of the type B (6) are realized by the maintenance of the current transformer body locality, the inspection and maintenance of the power failure are realized by the type C (7), the inspection and maintenance of the current transformer are realized by the conventional inspection, maintenance and test of the current transformer, and the inspection and maintenance of the current transformer are realized by the type D (8).
4. The residual magnetism overhauling method of the 10kV-110kV current transformer according to claim 1, characterized in that: and in the normal state (9), the residual magnetism in the iron core of the current transformer is small, D-class overhaul (8) is performed on the current transformer, in the attention state (10), the residual magnetism in the iron core of the current transformer is relatively large, C-class overhaul (7) is performed on the current transformer, in the abnormal state (11), the residual magnetism of the iron core of the current transformer is large, and B-class overhaul (6) is performed on the current transformer.
5. The residual magnetism overhauling method of the 10kV-110kV current transformer according to claim 1, characterized in that: when the open-circuit demagnetization method (12) is used, one winding with less turns is selected from the primary (or secondary) windings, and the rated primary (or secondary) current is conducted by 10 percent, and under the condition that other windings are open-circuit, the current is smoothly and slowly reduced to zero; when the closed-circuit demagnetization method (13) is used, a resistor which is 10-20 times of rated load is connected to the secondary winding, power frequency current is conducted to the primary winding, the current is increased from zero to 1.2 times of rated current, and then the current is uniformly and slowly reduced to zero.
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| CN207396711U (en) * | 2017-11-09 | 2018-05-22 | 国家电网公司 | The hookup of remanent magnetism in current transformer |
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| Title |
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| 杨志强: "剩磁对计量用电流互感器传变特性影响研究", 中国优秀硕士学位论文数据库工程科技II辑, 15 June 2019 (2019-06-15), pages 042 - 156 * |
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