CN110988610A - Novel inverted current transformer, insulation detection method and detection device - Google Patents
Novel inverted current transformer, insulation detection method and detection device Download PDFInfo
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- CN110988610A CN110988610A CN201911078924.2A CN201911078924A CN110988610A CN 110988610 A CN110988610 A CN 110988610A CN 201911078924 A CN201911078924 A CN 201911078924A CN 110988610 A CN110988610 A CN 110988610A
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
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Abstract
The invention relates to a novel inverted current transformer, an insulation detection method and a detection device, wherein the transformer comprises an inverted current transformer body and a first current sensor arranged at the lower part of a secondary lead tube of the inverted current transformer body, the secondary lead tube passes through the first current sensor, a first through hole is arranged on the secondary lead tube and positioned below the first current sensor, and a lead-out wire of the first current sensor passes through the first through hole and is led to a secondary junction box; the invention can monitor the insulation state of the inverted current transformer in real time, realize on-line monitoring and live detection, predict the insulation development trend of the inverted current transformer and effectively avoid explosion accidents.
Description
Technical Field
The invention belongs to the field of power transformers, and particularly relates to a novel inverted current transformer, an insulation detection method and a detection device.
Background
The inverted current transformer has the advantages of being easy to meet the requirement of high dynamic thermal stability current, small in radial size of the porcelain bushing, difficult to damp in the primary winding and the like, and is increasingly widely applied to a power grid. However, due to inherent reasons such as high head field strength, little insulating oil, poor shock resistance and the like, discharge and even explosion accidents are easy to happen in the operation process. The defect statistics shows that the main fault of the inverted current transformer is represented by main insulation breakdown between the primary guide rod and the secondary winding cover, no effective means is available for monitoring or detecting the insulation state of the inverted current transformer under the operation condition, and the transformer can only be developed from the defect after the defect occurs, and finally is developed into a transformer explosion accident, so that great potential safety hazard is brought to safe and stable operation of a power grid. At present, no targeted means can predict the fault of the inverted current transformer in operation in advance.
In order to solve the problems, the invention provides a novel inverted oil-immersed current transformer, wherein a zero-flux current sensor is arranged at the bottom of a secondary lead tube of the inverted current transformer, so that the inverted current transformer can be subjected to online monitoring and live detection of relative dielectric loss and capacitance, and the insulation state of the inverted current transformer can be predicted in advance.
Disclosure of Invention
The invention aims to solve the technical problem of providing a novel inverted current transformer, an insulation detection method and a detection device, solving the problems of online monitoring and live detection of the original inverted current transformer and realizing the predictability of the insulation state of the inverted current transformer.
The technical scheme adopted by the invention is as follows:
the utility model provides a novel inverted current transformer, its includes inverted current transformer body and sets up the first current sensor in the secondary lead pipe lower part of inverted current transformer body, the secondary lead pipe passes first current sensor, and the below that lies in first current sensor on the secondary lead pipe is provided with first through-hole, and first current sensor's lead-out wire passes first through-hole and leads to the secondary terminal box.
Furthermore, a second current sensor is arranged on the connection between the end screen and the secondary lead tube, and a lead-out wire of the second current sensor penetrates through the first through hole to lead to the secondary junction box.
Furthermore, the first current sensor is a zero-flux current sensor, a permalloy magnetic shielding layer is arranged outside an iron core of the zero-flux current sensor, and an outgoing line of the permalloy magnetic shielding layer is provided with an electromagnetic shielding layer.
Furthermore, the second current sensor is a zero-flux current sensor, a permalloy magnetic shielding layer is arranged outside an iron core of the second current sensor, and an outgoing line of the second current sensor is provided with an electromagnetic shielding layer.
Furthermore, an elastic insulating pad is arranged between the first current sensor and the base of the inverted current transformer body.
An insulation state detection device comprises a signal acquisition unit connected with a first current sensor and a second current sensor, a filtering unit connected with the signal acquisition unit, a signal amplification unit connected with the filtering unit and a processing host connected with the signal amplification unit.
A first current sensor is used for obtaining the current of a secondary lead tube of an inverted current transformer, a signal acquisition unit is used for inputting three-phase current signals into an insulation state detection device, and a filtering and amplifying unit is used for calculating the relative dielectric loss and the relative capacitance of the current of the secondary lead tube of the three-phase inverted current transformer, so that the insulation state of the inverted current transformer is obtained.
An insulation detection method is characterized in that a first current sensor and a second current sensor are respectively used for obtaining the current of a secondary lead tube of an inverted current transformer and the current of a secondary lead tube flowing into a tail screen.
The signal acquisition unit is used for inputting six current signals into the insulation state detection device, the filtering and amplifying unit is used for calculating the relative dielectric loss and the relative capacitance of the three-phase inverted current transformer based on the secondary lead tube current, and meanwhile, the relative dielectric loss value and the capacitance of the same inverted current transformer based on the secondary lead tube current and the end screen current flowing into the secondary lead tube can be calculated.
Further, the relative dielectric loss value is calculated according to the following formula:
Δtanδ＝tanδ2-tanδ1≈tan(δ2-δ1)＝tanα (1)
wherein, delta1Is I1A phase angle; delta2Is I2The phase angle.
Further, the relative capacitance is calculated according to the following formula:
wherein, I1、I2There are two ways of explanation:
1)I1for grounding current of secondary lead tube of inverted current transformer of a same phase of a parent2The current is the grounding current of a secondary lead tube of the inverted current transformer of the other phase of the same bus.
2)I1For the current of the connecting line between the end screen of a certain phase of inverted current transformer and a secondary lead tube, I2Therefore, the secondary lead tube of the inverted current transformerAnd (4) grounding current.
The invention has the positive effects that:
1) the insulation state of the inverted current transformer can be monitored in real time, the insulation development trend of the inverted current transformer can be predicted by online monitoring and live detection, and explosion accidents are effectively avoided.
2) The installed first current sensor and the second current sensor are both located at low potential positions, the insulation structure of the inverted current transformer is not influenced, and the influence on the electric field intensity of the inverted current transformer is small.
3) The first current sensor and the second current sensor are installed to have little influence on the secondary winding measurement accuracy. Because the secondary winding is located in the secondary lead pipe, the secondary lead pipe plays a natural shielding role for the secondary winding, and the measuring accuracy of the secondary winding cannot be influenced by the mounted sensor.
4) The on-line monitoring and the live detection of the inverted current transformer can be realized, and the requirements of state comprehensive perception of a power system in the power internet of things of national power grid limited companies are met.
Drawings
Fig. 1 is a schematic diagram of an inverted current transformer in accordance with an embodiment 1 of the present invention;
FIG. 2 is a schematic diagram illustrating the installation positions of a secondary lead tube and a first current sensor in accordance with embodiment 1 of the present invention;
FIG. 3 is a schematic view of a first through hole of a secondary lead tube according to embodiment 1 of the present invention;
fig. 4 is a schematic diagram of an inverted current transformer according to an embodiment 2 of the present invention;
FIG. 5 is a schematic view of the detecting device of the present invention;
FIG. 6 is a schematic diagram of the calculation of relative dielectric loss and capacitance of the current transformer according to the present invention when the current is in different phases with the same bus;
fig. 7 is a schematic diagram of the calculation of relative dielectric loss and capacitance of the current transformer when current flows at different positions of the current transformer.
In the attached drawing, 1-an inverted current transformer body, 2-a secondary lead tube, 3-a first current sensor, 4 and 10-lead wires and 5-a secondary lead wireThe device comprises a wire, 6-a first through hole, 7-a base, 8-an elastic insulating pad, 9-a second current sensor and 11-a tail screen outgoing wire; i is1-a secondary lead tube ground current 1 of the same phase as the parent; i is2-a secondary pin-tube ground current 2 of the same phase as the parent; i'1-a connection line current 1' of its end screen to the secondary lead tube; delta1-I1And ICThe phase angle difference of (a); delta2-I2And ICα '-I'1A phase angle; un-reference voltage.
Detailed Description
Example 1:
as shown in fig. 1-7, the novel inverted current transformer of the present invention includes an inverted current transformer body 1 and a first current sensor 3 disposed at a lower portion of a secondary lead tube 2 of the inverted current transformer body 1, wherein the secondary lead tube 2 passes through the first current sensor 3, a first through hole 6 is disposed at a position of the secondary lead tube 2, which is located at the first current sensor 3, an outgoing line 4 of the first current sensor 3 passes through the first through hole 6 and is led to a secondary junction box, and a secondary lead 5 is also led to the secondary junction box. And a lead-out wire mounting hole is reserved in the secondary junction box, and a sealing rubber gasket is mounted to prevent the interior of the secondary junction box from being affected with damp. An elastic insulating pad 8 is arranged between the first current sensor 3 and the base 7 of the inverted current transformer body. The first current sensor 3 is a zero-flux current sensor, and the outer part of an iron core and the leading-out wire of the first current sensor are provided with shielding layers, so that the influence of an electromagnetic field in the inverted current transformer on the measurement precision can be prevented. The elastic insulating pad 8 is arranged on the secondary lead pipe 2 between the first current sensor 3 and the base, so that direct rigid contact between the zero-flux current sensor and the base in the operation process of the inverted current transformer can be avoided, and the phenomenon that the zero-flux current sensor is damaged or inaccurate in measurement due to the fact that the zero-flux current sensor is directly transmitted by vibration of the transformer body is avoided.
The fixing mode of the zero-flux current sensor includes the following modes:
the installation method is as follows: the zero-flux current sensor is mounted in a groove of a fixed flange, and the fixed flange penetrates through a secondary lead pipe and is positioned above the bottom of the base.
The second installation mode: the zero-flux current sensor is arranged inside the circular insulating rubber plate, the upper portion of the circular insulating rubber plate is provided with a groove for fixing the zero-flux current sensor, the circular insulating rubber plate penetrates through the secondary lead tube and is fixed, and the position of the circular insulating rubber plate is located above the bottom of the base.
The mounting mode is three: and fixing the zero-flux current sensor on the secondary lead pipe in a binding mode or a pouring mode.
The insulation state device shown in fig. 4 includes a signal acquisition unit connected to the first current sensor, a filtering unit connected to the signal acquisition unit, a signal amplification unit connected to the filtering unit, and a processing host connected to the signal amplification unit. The zero-flux current sensor and the insulation state monitoring device obtain current signals through a zero-flux sensor leading-out terminal in the secondary wiring box for calculation, and online monitoring and live detection of the insulation state of the inverted current transformer can be realized.
In the embodiment, the insulation detection method obtains the grounding current flowing through the secondary lead tube through the first current sensor, and determines the insulation state of the inverted current transformer by calculating the dielectric loss and capacitance of the inverted current transformer relative to the inverted current transformer in different phases with the same bus.
Specifically, the current of the secondary lead tube of the inverted current transformer is obtained by using a zero-flux current sensor, a three-phase current signal is input into an insulation state detection device by using a signal acquisition unit, the relative dielectric loss of the current of the secondary lead tube of the three-phase inverted current transformer is calculated by using a calculation method shown in a formula (1) through a filtering and amplifying unit, and the relative capacitance of the current of the secondary lead tube of the three-phase inverted current transformer is calculated by using a calculation method shown in a formula (2), so that the insulation state of the inverted current transformer is obtained, and the calculation principle is shown in figure 6.
Δtanδ＝tanδ2-tanδ1≈tan(δ2-δ1)＝tanα (1)
Wherein, I1For grounding current of secondary lead tube of inverted current transformer of a same phase of a parent2The current is the grounding current of a secondary lead tube of the inverted current transformer of the other phase of the same bus.
Example 2
As shown in fig. 4, the end screen lead-out wire 11 of the partially-structured inverted current transformer body 1 is a soft copper wire and is directly welded to the secondary lead tube 2. For such a form, a second current sensor 9 is additionally provided on the basis of embodiment 1, the second current sensor 9 passes through a tap lead 11, and a lead 10 thereof is led to the secondary junction box through a second through hole.
The insulation detection method aiming at the structural form can realize the insulation state judgment of the current transformer by calculating the relative dielectric loss and capacitance of the current transformer between phases with the same parent and also by calculating the relative dielectric loss and capacitance of the current transformer through the currents measured by the first sensor and the second sensor.
Specifically, a zero-flux current sensor is used for obtaining the secondary lead tube current of the inverted current transformer and the end screen inflow secondary lead tube current. The signal acquisition unit is used for inputting six current signals into the insulation state detection device, and through the filtering and amplifying unit, the relative dielectric loss and the relative capacitance of the secondary lead tube current of the three-phase inverted mutual inductor can be calculated by adopting calculation methods shown in formulas (1) and (2), and the relative dielectric loss value and the capacitance of the secondary lead tube current and the secondary lead tube current flowing into the end screen of the same inverted mutual inductor can also be calculated by adopting calculation methods shown in formulas (1) and (2).
In this embodiment, I1And I2Has changed the meaning of (I)1For the current of the connecting line between the end screen of a certain phase of inverted current transformer and a secondary lead tube, I2Therefore, the secondary lead tube of the inverted current transformer is grounded.
The invention improves the structure of the existing inverted current transformer, solves the problem that the insulation state of the original inverted current transformer cannot be monitored on line and detected in a charged way, realizes the predictability of the insulation state of the inverted current transformer, and can effectively avoid the explosion accident caused by the initial defect development of the inverted current transformer.
The above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.
Claims (10)
1. The utility model provides a novel inverted current transformer, its characterized in that it includes inverted current transformer body (1) and sets up first current sensor (3) in secondary lead tube (2) lower part of inverted current transformer body (1), first current sensor (3) are passed in secondary lead tube (2), and the department that sets up that lies in first current sensor (3) on secondary lead tube (2) has first through-hole (6), and lead-out wire (4) of first current sensor (3) pass first through-hole (6) and lead to the secondary terminal box.
2. The novel inverted current transformer according to claim 1, characterized in that a second current sensor (9) is arranged on the end screen lead-out wire (11), a second through hole corresponding to the position of the second current sensor (9) is arranged on the secondary lead tube (2), and the lead-out wire (10) of the second current sensor (9) passes through the second through hole and leads to the secondary junction box.
3. The novel inverted current transformer according to claim 1, characterized in that the first current sensor (3) is a zero-flux current sensor, the iron core of the zero-flux current sensor is externally provided with a permalloy magnetic shielding layer, and the lead wire of the zero-flux current sensor is provided with an electromagnetic shielding layer.
4. A novel inverted current transformer according to claim 2, characterized in that said second current sensor (9) is a zero-flux current sensor having permalloy magnetic shielding layer on the outside of its iron core and electromagnetic shielding layer on its lead-out wire.
5. A novel inverted current transformer according to claim 1, characterized in that an elastic insulating pad (8) is arranged between the first current sensor (3) and the base (7) of the inverted current transformer body.
6. An insulation state detection device is characterized by comprising a signal acquisition unit connected with a first current sensor and a second current sensor, a filtering unit connected with the signal acquisition unit, a signal amplification unit connected with the filtering unit and a processing host connected with the signal amplification unit.
7. An insulation detection method using the novel inverted current transformer as claimed in claim 1, characterized in that it uses the first current sensor to obtain the secondary lead tube current of the inverted current transformer, uses the signal acquisition unit to input the three-phase current signal into the insulation state detection device, and calculates the relative dielectric loss and relative capacitance of the secondary lead tube current of the three-phase inverted current transformer through the filtering and amplifying unit, thereby obtaining the insulation state of the inverted current transformer.
8. An insulation detection method using the novel inverted current transformer of claim 2, characterized in that the method obtains the secondary lead tube current and the end screen inflow secondary lead tube current of the inverted current transformer by using the first current sensor and the second current sensor respectively;
the signal acquisition unit is used for inputting six current signals into the insulation state detection device, the relative dielectric loss and the relative capacitance of the secondary lead tube current of the three-phase inverted transformer are calculated through the filtering and amplifying unit, and meanwhile, the relative dielectric loss value and the capacitance of the secondary lead tube current and the secondary lead tube current flowing into the same inverted current transformer through a tail screen can be calculated.
9. An insulation detection method as claimed in claim 7 or 8, characterized in that said relative dielectric loss value is calculated according to the following formula:
wherein the content of the first and second substances,
is composed of
A phase angle;
is composed of
The phase angle.
10. The insulation detection method according to claim 7 or 8, wherein said relative capacitance is calculated according to the following formula:
wherein the content of the first and second substances,
、
there are two ways of explanation:
1）
the secondary lead tube grounding current of the inverted current transformer of a certain phase of the same bus,
the current is the grounding current of a secondary lead tube of the inverted current transformer of the other phase of the same bus;
2）
the current of the connecting line between the end screen of a certain phase of inverted current transformer and a secondary lead tube,
therefore, the secondary lead tube of the inverted current transformer is grounded.
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| CN201911078924.2A CN110988610A (en) | 2019-11-07 | 2019-11-07 | Novel inverted current transformer, insulation detection method and detection device |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201911078924.2A CN110988610A (en) | 2019-11-07 | 2019-11-07 | Novel inverted current transformer, insulation detection method and detection device |
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101707127A (en) * | 2009-12-01 | 2010-05-12 | 中国西电电气股份有限公司 | Oil-immersed inverted current transformer with function of insulation online monitoring |
| CN102136359A (en) * | 2011-01-10 | 2011-07-27 | 东北电力科学研究院有限公司 | Novel oil immersed inverted vertical current transformer and insulation detection method thereof |
| CN202404198U (en) * | 2011-09-30 | 2012-08-29 | 宁夏电力公司电力科学研究院 | Utra-high-frequency partial discharge detection device of SF6 current transformer |
| CN203617118U (en) * | 2013-12-26 | 2014-05-28 | 保定天威互感器有限公司 | Oil-immersed inverted current transformer |
| CN104297654A (en) * | 2014-10-22 | 2015-01-21 | 国家电网公司 | Model for simulating multiple protrusion defects in oil immersion headstand type current transformer |
-
2019
- 2019-11-07 CN CN201911078924.2A patent/CN110988610A/en active Pending
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101707127A (en) * | 2009-12-01 | 2010-05-12 | 中国西电电气股份有限公司 | Oil-immersed inverted current transformer with function of insulation online monitoring |
| CN102136359A (en) * | 2011-01-10 | 2011-07-27 | 东北电力科学研究院有限公司 | Novel oil immersed inverted vertical current transformer and insulation detection method thereof |
| CN202404198U (en) * | 2011-09-30 | 2012-08-29 | 宁夏电力公司电力科学研究院 | Utra-high-frequency partial discharge detection device of SF6 current transformer |
| CN203617118U (en) * | 2013-12-26 | 2014-05-28 | 保定天威互感器有限公司 | Oil-immersed inverted current transformer |
| CN104297654A (en) * | 2014-10-22 | 2015-01-21 | 国家电网公司 | Model for simulating multiple protrusion defects in oil immersion headstand type current transformer |
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| Title |
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| 王卓然 等: "220kV电流互感器故障分析及处理", 《河北电力技术》 * |
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Application publication date: 20200410 |