CN111537797B - System and method for measuring insulation resistance of transformer substation without disassembling lead - Google Patents
System and method for measuring insulation resistance of transformer substation without disassembling lead Download PDFInfo
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- CN111537797B CN111537797B CN202010413248.6A CN202010413248A CN111537797B CN 111537797 B CN111537797 B CN 111537797B CN 202010413248 A CN202010413248 A CN 202010413248A CN 111537797 B CN111537797 B CN 111537797B
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/025—Measuring very high resistances, e.g. isolation resistances, i.e. megohm-meters
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/14—Measuring resistance by measuring current or voltage obtained from a reference source
Abstract
The invention relates to a system and a method for measuring insulation resistance of a transformer substation without disassembling a lead, wherein the system comprises a power supply module, a resistor R with known resistance value1A resistor R with a known resistance value2The first voltage measuring module and the second voltage measuring module; the measurement power supply module comprises a terminal L, a shielding terminal G and a grounding terminal E, wherein the terminal L and a resistor R1And a resistance R2The input end of the transformer is connected, and the grounding end E is grounded; first voltage measuring module measuring resistance R1The second voltage measuring module is respectively connected with the resistor R1And a resistance R2Is connected to measure the voltage values of the two nodes. By the system and the method, the insulation resistance value of the transformer can be obtained without disassembling the lead, and the insulation state and the change rule of the transformer can be accurately judged; on the other hand, the staff need not to tear the work of lead wire open, has improved the efficiency of work and has reduced the potential safety hazard of working process.
Description
Technical Field
The invention relates to the field of electric power, in particular to a system and a method for measuring insulation resistance of a transformer substation without disassembling a lead.
Background
When the transformer is subjected to preventive tests, the insulation resistance value of the transformer needs to be measured, and the transformer can be subjected to conventional tests only by removing leads connected with buses or primary equipment on each side of the transformer. Especially for transformers of 220kV, 500kV and above, the height of the top end of the sleeve above the ground is more than ten meters, so that expensive overhead working trucks, bucket arm trucks and tools for ensuring safety are required to be purchased, and falling risks exist when testers ascend; on the other hand, the wire disconnecting and recovering process accounts for about 40-65% of the whole test time, and a large amount of manpower and material resources are consumed; meanwhile, the lead is easily broken and damaged when being disassembled and assembled, and the poor contact between the equipment wire clamp of the lead and the conducting rod of the sleeve can be caused, so that the contact resistance of the joint is increased and the overheating phenomenon is caused; and potential safety hazards of equipment such as lead cable insulation damage and transformer insulation sleeve oil leakage caused by disconnecting and connecting the lead.
In the prior art, the insulation resistance of the transformer without disconnecting the lead is measured by a method, namely the insulation resistance value obtained by measuring the transformer without disconnecting the lead is compared with original data obtained by disconnecting the lead and basic data obtained by measuring the transformer without disconnecting the lead, and whether the insulation state of the transformer is good or not is judged according to the change of the insulation resistance value of the transformer measured without disconnecting the lead. According to the method for measuring the insulation resistance of the transformer without disassembling the lead, the insulation resistance of the transformer cannot be measured because the transformer is connected with a bus and/or primary equipment, the insulation state and the change rule of the transformer cannot be accurately judged, and the method is only used for judging whether the insulation resistance of the transformer is within a normal value range.
Disclosure of Invention
The invention aims to solve the problem that the resistance value of the insulation resistor of the transformer cannot be accurately measured in the prior art, and provides a system and a method for measuring the insulation resistor of the transformer substation without disassembling a lead, so that the resistance value of the insulation resistor of the transformer can be accurately measured under the condition of not disassembling the lead.
In order to solve the technical problems, the invention adopts the technical scheme that: system for measuring insulation resistance of transformer substation without disassembling lead, power module and resistor R with known resistance value1A resistor R with a known resistance value2The first voltage measuring module and the second voltage measuring module;
the measurement power supply module comprises a wiring terminal L, a shielding terminal G and a grounding terminal E, wherein the wiring terminal L and the resistor R1And the resistance R2The input end of the grounding end E is connected with the ground;
the first voltage measurement module measures a resistance R1The second voltage measuring module is respectively connected with the resistor R1And a resistance R2Is connected to measure the voltage values of the two nodes.
The system is connected with the transformer to form a bridge circuit, the insulation resistance of the transformer is converted by obtaining the voltage values measured by the voltage measuring modules, the calculation is accurate, and the lead does not need to be detached.
Preferably, the voltage measuring device further comprises an upper computer, and the upper computer receives voltage value data collected by the first voltage measuring module and the second voltage measuring module. And the voltage data of the two voltage measurement modules are quickly read through the upper computer.
Preferably, the system further comprises a system power supply module, wherein the system power supply module inverts the direct-current storage battery into 220V alternating-current voltage, and provides a floating power supply for the upper computer, the first voltage measurement module and the second voltage measurement. The first voltage measuring module and the second voltage measuring module are high-precision voltage measuring instruments, the voltage resistance to the ground is limited, and a power supply source needs to float to the ground.
Preferably, the measurement power supply module and the resistor R1The resistor R2The first voltage measuring module, the second voltage measuring module, the system power supply module and the upper computer are all placed in an electromagnetic shielding cabinet. When the system is used, the high-voltage test wire shielding layer and the electromagnetic shielding cabinet shell of the insulation resistance measurement system without disconnecting the transformer are connected together, so that the influence of surface leakage current is eliminated, and the measurement calculation is more accurate.
Preferably, the measurement power supply module comprises a power supply E connected in series in sequencesEquivalent internal resistance R of power supplyiAdditional resistors R for current limiting and filteringmAnd a sampling resistor RoThe terminal L is electrically connected with the sampling resistor RoThe shielding end G is electrically connected with the equivalent internal resistance R of the power supplyiThe grounding terminal E is electrically connected with the power supply EsTo the output terminal of (a).
Preferably, the resistor R is connected with2And an off-line equivalent device electrically connected with the output point.
Based on the system, the shielding end G is connected with a high-voltage porcelain insulator sleeve of the transformer, and the resistor R is connected1Is electrically connected with the neutral line of the transformer, and the resistor R is connected with the neutral line of the transformer2The output end of the transformer is electrically connected with the common end of the high-voltage end Y-shaped three-phase output end of the transformer in short circuit; obtaining insulation resistance measured values of the transformer:
wherein R isx1Is a pi-type equivalent circuit resistor of the transformer; r is the equivalent insulation resistance of the transformer; r1Is a resistance R1The resistance value of (1); esMeasuring the power value of the power modules connected in series; Δ u is a voltage value measured by the first voltage measurement module; Δ v is the voltage value measured by the second voltage measurement module.
Preferably, the equivalent insulation resistance of the transformer is calculated by the following formula:
wherein R is1Is a resistance R1The resistance value of (1); Δ u is a voltage value measured by the first voltage measurement module; Δ v is the voltage value measured by the second voltage measurement module.
Preferably, the low-voltage end Y-shaped three-phase output end of the transformer is grounded.
Preferably, the other terminal of the off-line equivalent device is grounded.
Compared with the prior art, the invention has the beneficial effects that: by the system and the method, the insulation resistance value of the transformer can be obtained without disassembling the lead, and the insulation state and the change rule of the transformer can be accurately judged; on the other hand, the staff need not to tear the work of lead wire open, has improved the efficiency of work and has reduced the potential safety hazard of work.
Drawings
FIG. 1 is a schematic structural diagram of a system for measuring insulation resistance of a transformer substation without disassembling a lead according to the present invention;
FIG. 2 is an internal circuit diagram of the measurement power supply module of the present invention;
FIG. 3 is a measurement schematic diagram of a method for measuring insulation resistance of a transformer substation without disassembling a lead according to the invention;
fig. 4 is an equivalent circuit diagram of a method for measuring insulation resistance of a substation transformer without disassembling a lead wire.
Detailed Description
The drawings are for illustrative purposes only and are not to be construed as limiting the patent; for the purpose of better illustrating the embodiments, certain features of the drawings may be omitted, enlarged or reduced, and do not represent the size of an actual product; it will be understood by those skilled in the art that certain well-known structures in the drawings and descriptions thereof may be omitted. The positional relationships depicted in the drawings are for illustrative purposes only and are not to be construed as limiting the present patent.
The same or similar reference numerals in the drawings of the embodiments of the present invention correspond to the same or similar components; in the description of the present invention, it should be understood that if there are terms such as "upper", "lower", "left", "right", "long", "short", etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the drawings, it is only for convenience of description and simplicity of description, but does not indicate or imply that the device or element referred to must have a specific orientation, be constructed in a specific orientation, and be operated, and therefore, the terms describing the positional relationships in the drawings are only used for illustrative purposes and are not to be construed as limitations of the present patent, and specific meanings of the terms may be understood by those skilled in the art according to specific situations.
The technical scheme of the invention is further described in detail by the following specific embodiments in combination with the attached drawings:
example 1
Referring to fig. 1-4, an embodiment of a system for measuring insulation resistance without disassembling a lead of a transformer in a transformer substation is shown, in which a power module 1 and a resistor R with a known resistance value are measured1A resistor R with a known resistance value2The system comprises a first voltage measuring module 2, a second voltage measuring module 3, an upper computer and a system power supply module;
the measurement power supply module 1 comprises a terminal L, a shielding terminal G and a grounding terminal E, wherein the terminal L and a resistor R1And a resistance R2The input end of the transformer is connected, and the grounding end E is grounded;
the first voltage measuring module 2 measures the resistance R1The second voltage measuring module 3 and the resistor R respectively1And a resistance R2Is connected to measure the voltage values of the two nodes.
The upper computer receives the voltage value data collected by the first voltage measuring module 2 and the second voltage measuring module 3. And the voltage data of the two voltage measurement modules are quickly read through the upper computer.
The system power supply module inverts the direct-current storage battery into 220V alternating-current voltage and provides a floating power supply for the upper computer, the first voltage measuring module 2 and the second voltage measurement.
Wherein, the power supply module 1 and the resistor R are measured1Resistance R2The first voltage measuring module 2, the second voltage measuring module 3, the system power supply module and the upper computer are all placed in the electromagnetic shielding cabinet. When the system is used, the high-voltage test wire shielding layer and the electromagnetic shielding cabinet shell of the insulation resistance measurement system without disconnecting the transformer are connected together, so that the influence of surface leakage current is eliminated, and the measurement calculation is more accurate.
Specifically, the measurement power supply module 1 comprises a power supply E connected in series in sequencesEquivalent internal resistance R of power supplyiAdditional resistors R for current limiting and filteringmAnd a sampling resistor RoThe terminal L is electrically connected with the sampling resistor RoThe shielding end G is electrically connected with the equivalent internal resistance R of the power supplyiThe input end and the grounding end E of the power supply E are electrically connectedsTo the output terminal of (a).
In addition, the device also comprises a resistor R2An off-line equivalent device 4 to which the output point is electrically connected.
The working principle or working process of the invention is as follows: measuring power supply and resistance R1And R2Connected with and respectively electrically connected with the high-voltage neutral wire leading-out end of the transformer 5 and the leading-out end short-circuited with the high-voltage Y-type three-phase output end A, B, C in sequence, and the measuring power supply module 1 and the resistor R1And R2The transformer 5 and the equivalent device connected to the transformer are connected to form a bridge circuit. Particularly, the shielding end G is connected with a high-voltage porcelain insulator sleeve of the transformer 5, and the resistor R is connected1Is electrically connected to the neutral line of the transformer 5, and the resistor R is connected to the neutral line2The output end of the transformer is electrically connected with the common end of the high-voltage end Y-shaped three-phase output end of the transformer 5 in short circuit; the insulation resistance value of the transformer 5 is obtained by calculation using the measured value.
The beneficial effects of this embodiment: by the system, the insulation resistance value of the transformer 5 can be obtained without disassembling the lead, and the insulation state and the change rule of the transformer can be accurately judged; on the other hand, the staff need not to tear the work of lead wire open, has improved the efficiency of work and has reduced the potential safety hazard of work.
Example 2
As shown in fig. 3-4, an embodiment of a method for measuring insulation resistance of a transformer substation without detaching a lead is provided, based on the system of embodiment 1, a shielding end G is connected with a high-voltage porcelain insulator sleeve of a transformer 5, and a resistance R is connected1Is electrically connected to the neutral line of the transformer 5, and the resistor R is connected to the neutral line2The output end of the transformer is electrically connected with the common end of the high-voltage end Y-shaped three-phase output end of the transformer 5 in short circuit; obtaining insulation resistance measured values of the transformer:
wherein R isx1Is a pi-type equivalent circuit resistor of the transformer; r is the equivalent insulation resistance of the transformer; r1Is a resistance R1The resistance value of (1); esIs a measuring power supplyThe power value of the modules in series; Δ u is a voltage value measured by the first voltage measurement module; Δ v is the voltage value measured by the second voltage measurement module.
Preferably, the equivalent insulation resistance of the transformer is calculated by the following formula:
wherein R is1Is a resistance R1The resistance value of (1); Δ u is a voltage value measured by the first voltage measurement module 2; Δ v is a voltage value measured by the second voltage measurement module 3.
The low-voltage end Y-shaped three-phase output ends a, b and b of the transformer are grounded; the other terminal of the off-line equivalent device 4 is grounded. The multipoint grounding of the transformer is simplified into a pi-type equivalent circuit model to calculate the insulation resistance value of the lead without disassembling.
It should be understood that the above-described embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. 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. Any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the claims of the present invention.
Claims (4)
1. A method for measuring insulation resistance of a transformer substation without disassembling a lead comprises a power supply module, a resistor R with a known resistance value1A resistor R with a known resistance value2A first voltage measuring module, a second voltage measuring module and the resistor R2An off-line equivalent device with an output point electrically connected; the measurement power supply module comprises a wiring terminal L, a shielding terminal G and a grounding terminal E, wherein the wiring terminal L and the resistor R1And the resistance R2The input end of the grounding end E is connected with the ground; the first voltage measurement module measures a resistance R1The second voltage measuring moduleRespectively connected with the resistors R1And a resistance R2The output ends of the two nodes are connected, and the voltage values of the two nodes are measured; the measurement power supply module comprises a power supply E which is connected in series in sequencesEquivalent internal resistance R of power supplyiAdditional resistors R for current limiting and filteringmAnd a sampling resistor RoThe terminal L is electrically connected with the sampling resistor RoThe shielding end G is electrically connected with the equivalent internal resistance R of the power supplyiThe grounding terminal E is electrically connected with the power supply EsAn output terminal of (a); it is characterized in that the shielding end G is connected with a high-voltage porcelain insulator sleeve of a transformer, and the resistor R is connected with the high-voltage porcelain insulator sleeve of the transformer1Is electrically connected with the neutral line of the transformer, and the resistor R is connected with the neutral line of the transformer2The output end of the transformer is electrically connected with the common end of the high-voltage end Y-shaped three-phase output end of the transformer in short circuit; obtaining insulation resistance measured values of the transformer:
wherein R isx1Is a pi-type equivalent circuit resistor of the transformer; r is the equivalent insulation resistance of the transformer; r1Is a resistance R1The resistance value of (1); esMeasuring the power value of the power modules connected in series; Δ u is a voltage value measured by the first voltage measurement module; Δ v is a voltage value measured by the second voltage measurement module.
2. The method for measuring the insulation resistance of the transformer substation without disassembling the lead of the transformer substation according to claim 1, wherein the equivalent insulation resistance of the transformer is calculated by the following formula:
wherein R is1Is a resistance R1The resistance value of (1); Δ u is a voltage value measured by the first voltage measurement module; Δ v is a voltage value measured by the second voltage measurement module.
3. The method for measuring the insulation resistance of the transformer substation without disassembling the lead of the transformer according to claim 2, wherein a low-voltage end Y-shaped three-phase output end of the transformer is grounded.
4. The method for measuring insulation resistance of the substation transformer without disassembling the lead of claim 3, wherein the other terminal of the off-line equivalent equipment is grounded.
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| CN202010413248.6A CN111537797B (en) | 2020-05-15 | 2020-05-15 | System and method for measuring insulation resistance of transformer substation without disassembling lead |
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Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106249053A (en) * | 2016-08-19 | 2016-12-21 | 汪锐 | Capacitance type potential transformer dielectric loss method of testing based on resonance characteristic |
| CN110231582A (en) * | 2019-06-18 | 2019-09-13 | 贵州电网有限责任公司 | A method of measurement and calculating transformer π model are saturated excitation curve |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN101354418B (en) * | 2008-09-22 | 2011-07-13 | 河南省电力公司商丘供电公司 | Power transformer test method without disconnecting wire |
| CN103336186A (en) * | 2012-12-18 | 2013-10-02 | 辽宁省电力有限公司检修分公司 | Method for testing transformer equipment without disassembling lead |
| JP5679480B2 (en) * | 2013-04-22 | 2015-03-04 | 中国電力株式会社 | Indirect AC megger measuring instrument and insulation resistance measuring method |
| CN110045188B (en) * | 2019-03-27 | 2021-03-02 | 广东电网有限责任公司 | System and method for measuring insulation resistance of transformer without dismounting high-voltage side lead |
| CN110442895B (en) * | 2019-05-24 | 2021-05-14 | 华北电力大学 | High-frequency transformer electromagnetic transient equivalent modeling method considering capacitance effect |
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Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN106249053A (en) * | 2016-08-19 | 2016-12-21 | 汪锐 | Capacitance type potential transformer dielectric loss method of testing based on resonance characteristic |
| CN110231582A (en) * | 2019-06-18 | 2019-09-13 | 贵州电网有限责任公司 | A method of measurement and calculating transformer π model are saturated excitation curve |
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