CN112540233B - Dielectric loss measurement method for 220KV voltage transformer disassembly-free lead - Google Patents
Dielectric loss measurement method for 220KV voltage transformer disassembly-free lead Download PDFInfo
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- CN112540233B CN112540233B CN202011212053.1A CN202011212053A CN112540233B CN 112540233 B CN112540233 B CN 112540233B CN 202011212053 A CN202011212053 A CN 202011212053A CN 112540233 B CN112540233 B CN 112540233B
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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
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
- G01R27/2688—Measuring quality factor or dielectric loss, e.g. loss angle, or power factor
- G01R27/2694—Measuring dielectric loss, e.g. loss angle, loss factor or power factor
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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
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
- G01R27/2605—Measuring capacitance
Abstract
The invention discloses a dielectric loss measurement method of a 220KV voltage transformer lead wire disassembly-free, which comprises the following steps: connecting the resonant circuit with the circuit to be detected in parallel, and connecting the equivalent circuit with the resonant circuit; rotating the inductance value knob, observing the value of the ammeter, stopping when the current is minimum, and recording the value as a first capacitance current; and rotating the inductance knob, and recording the current of the second capacitor and the third capacitor when the total current of the circuit is minimum. The dielectric loss measurement method of the 220KV voltage transformer lead wire disassembly-free, firstly, the parallel resonance characteristic of C, L is utilized to accurately measure the capacitance of the 220KV voltage transformer lead wire under the condition that the high-voltage lead wire is not disassembled, so that ascending operation is avoided, and safe operation is ensured; secondly, through adopting ampere meter and adjustable coil L that the high pressure end measured, can detect minimum total current when adjusting L, realize the parallel resonance of circuit, L changes its inductance by inductance knob, and the final effect of parallel resonance takes place with the parallelly connected way of target.
Description
Technical Field
The invention relates to the technical field of data transmission, in particular to a dielectric loss measurement method for a 220KV voltage transformer lead disassembly-free lead.
Background
Along with the continuous development of society, data transmission is more and more common, but because the data transmission is too frequent, mutual interference between data often occurs during data transmission, so that information insufficiency or information deviation occurs during data transmission, at the moment, errors exist between the data received by a receiving end and the data sent by a sending end, and the accuracy of the information is affected.
Disclosure of Invention
The invention mainly aims to provide a dielectric loss measurement method for a 220KV voltage transformer lead without disassembly, which can effectively solve the problems in the background technology.
In order to achieve the above purpose, the technical scheme adopted by the invention is as follows:
a dielectric loss measurement method of a 220KV voltage transformer lead wire without disassembly comprises the following steps:
and (3) circuit connection: connecting the resonant circuit with the circuit to be detected in parallel, and connecting the equivalent circuit with the resonant circuit;
first electric capacity C11 electric current detects: rotating the inductance value knob, observing the value of the ammeter A, stopping when the current is minimum, and recording the value as the current of the first capacitor C11;
second capacitor C12 and third capacitor C2 current detection: the inductance knob is rotated, and when the total current of the circuit is minimum, the current is recorded as the current of the second capacitor C12 and the third capacitor C2.
Preferably, the equivalent circuit includes an ammeter a and a second adjustable inductance L1.
Preferably, when the current of the first capacitor C11 is detected, the equivalent circuit is connected with the resonant circuit as follows: the first capacitor C11, the second capacitor C12, the third capacitor C2 and the second adjustable inductor L1 are sequentially connected in series, a power supply is connected to one end, far away from the second capacitor C12, of the first capacitor C11, the first inductor L is connected to two ends of the third capacitor C2 and the second adjustable inductor L1 in parallel, one end of the ammeter A is connected between the first capacitor C11 and the second capacitor C12, and the other end of the ammeter A is connected to a test high-voltage line.
Preferably, the first inductor L includes two sets of coils, one end of one coil is connected to a wire between the second capacitor C12 and the third capacitor C2, the other end is connected to a power supply, and two ends of the other coil are connected through wires.
Preferably, in the current detection of the first capacitor C11, the third capacitor C2, the second adjustable inductor L1 and the first inductor L form a series-parallel circuit, when the current is minimum, the branch z= (xl1+xc2)// XL, and when the condition that the branch generates parallel resonance is that Z tends to infinity, namely:
Z＝(jwX L1 +1/jwC 2 )//jwX L ＝jwX L /(1-w 2 C 2 L/(1-w 2 C 2 L 1 ))
to satisfy the condition:
preferably, when the currents of the second capacitor C12 and the third capacitor C2 are detected, the equivalent circuit and the resonant circuit are connected as follows: the first capacitor C11, the second capacitor C12 and the third capacitor C2 are sequentially connected in series, one end of the first capacitor C11 far away from the second capacitor C12 is connected to a power supply, one end of the second adjustable inductor L1 in the equivalent circuit is connected between the first capacitor C11 and the second capacitor C12, the other end of the second adjustable inductor L is connected with the power supply, and the ammeter A in the equivalent circuit is connected with the first inductor L in parallel.
Preferably, the first inductor L includes two sets of coils, one end of one coil is connected to a wire between the second capacitor C12 and the third capacitor C2, the other end is connected to a power supply, and two ends of the other coil are respectively connected to two ends of the ammeter a.
Preferably, the inductance adjustment range of the third capacitor C2 is 0-1000uH, and the external of the equivalent circuit device is grounded.
Preferably, in the current detection of the second capacitor C12 and the third capacitor C2, l1=1/w when the total current of the circuit is minimum 2 C11。
Compared with the prior art, the invention has the following beneficial effects:
firstly, the capacitance of the high-voltage lead is accurately measured under the condition that the high-voltage lead is not removed by utilizing the parallel resonance characteristics of the capacitor and the inductor, so that ascending operation is avoided, and safe operation is ensured;
secondly, through adopting ampere meter and adjustable coil L that the high pressure end was measured, the range can be adjusted to the ampere meter for detect circuit total current size, when the minimum total current of detection was adjusted L in the test, realize the parallel resonance of circuit, L changes its inductance through inductance knob, and the effect of parallel resonance takes place with the parallelly connected way of target finally.
Drawings
FIG. 1 is a diagram of a resonant circuit in a dielectric loss measurement method of a 220KV voltage transformer lead wire without disassembly;
FIG. 2 is a diagram of an equivalent circuit connected to a resonant circuit in a dielectric loss measurement method of a 220KV voltage transformer lead wire without disassembly according to the present invention;
fig. 3 is an equivalent circuit diagram of a dielectric loss measurement method of a 220kv voltage transformer lead without disassembly according to the present invention;
FIG. 4 is a second circuit diagram of an equivalent circuit connected with a resonant circuit in a dielectric loss measurement method of a 220KV voltage transformer lead wire without disassembly according to the present invention;
fig. 5 is a block diagram of the overall flow in the dielectric loss measurement method of the 220kv voltage transformer lead disassembly-free according to the present invention.
In the figure: A. an ammeter; c11, a first capacitor; c12, a second capacitor; c2, a third capacitor; l, a first inductor; l1, a second adjustable inductor.
Detailed Description
The invention is further described in connection with the following detailed description, in order to make the technical means, the creation characteristics, the achievement of the purpose and the effect of the invention easy to understand.
As shown in fig. 1-5, a dielectric loss measurement method for a 220kv voltage transformer lead disassembly-free includes the following steps:
and (3) circuit connection: connecting the resonant circuit with the circuit to be detected in parallel, and connecting the equivalent circuit with the resonant circuit;
first electric capacity C11 electric current detects: rotating the inductance value knob, observing the value of the ammeter A, stopping when the current is minimum, and recording the value as the current of the first capacitor C11;
second capacitor C12 and third capacitor C2 current detection: the inductance knob is rotated, and when the total current of the circuit is minimum, the current is recorded as the current of the second capacitor C12 and the third capacitor C2.
The equivalent circuit includes an ammeter a and a second adjustable inductance L1.
When the current of the first capacitor C11 is detected, the equivalent circuit is connected with the resonant circuit as follows: first electric capacity C11, second electric capacity C12 and third electric capacity C2 and second adjustable inductance L1 are established ties in proper order earlier to insert the power in the one end that first electric capacity C11 kept away from second electric capacity C12, first inductance L connects in parallel at third electric capacity C2 and second adjustable inductance L1 both ends, ampere meter A's one end is connected between first electric capacity C11 and second electric capacity C12, and the other end inserts experimental high-voltage line, and first inductance L includes two sets of coils, and one of them coil's one end is connected on the wire between second electric capacity C12 and third electric capacity C2, and the other end is connected with the power, and the both ends of another coil are passed through the wire and are connected.
In the current detection of the first capacitor C11, the third capacitor C2, the second adjustable inductor L1 and the first inductor L form a series-parallel circuit, when the current is minimum, the branch z= (xl1+xc2)// XL, and when the condition that the branch generates parallel resonance is that Z tends to infinity, namely:
Z＝(jwX L1 +1/jwC 2 )//jwX L ＝jwX L /(1-w 2 C 2 L/(1-w 2 C 2 L 1 ))
to satisfy the condition:
when the currents of the second capacitor C12 and the third capacitor C2 are detected, the equivalent circuit and the resonant circuit are connected as follows: the first capacitor C11, the second capacitor C12 and the third capacitor C2 are sequentially connected in series, one end of the first capacitor C11 far away from the second capacitor C12 is connected to a power supply, one end of the second adjustable inductor L1 in the equivalent circuit is connected between the first capacitor C11 and the second capacitor C12, the other end of the second adjustable inductor L is connected with the power supply, an ammeter A in the equivalent circuit is connected with the first inductor L in parallel, the first inductor L comprises two groups of coils, one end of one coil is connected to a wire between the second capacitor C12 and the third capacitor C2, the other end of the first coil is connected with the power supply, two ends of the other coil are respectively connected with two ends of the ammeter A, and in current detection of the second capacitor C12 and the third capacitor C2, when the total current of the circuit is minimum, L1=1/w 2 C11。
The inductance value adjusting range of the third capacitor C2 is 0-1000uH, and the outside of the equivalent circuit device is grounded.
Fig. 1 is an equivalent circuit diagram of the interior of a CVT, and the dielectric loss test is one of the routine test projects of the CVT, and is very sensitive and effective in finding distributed defects such as insulation aging, moisture and the like.
Most of the conventional positive connection methods are adopted in the dielectric loss test of the first capacitor C11 at the upper part of the 220kV CVT, and the primary lead wire needs to be removed in the operation process of the method. The other method is a reverse connection method, and the release can complete the test without dismantling the lead, but the error is larger, which is unfavorable for analyzing the running state of the test equipment. The dielectric loss measurement of the second capacitor C12 and the third capacitor C2 in 220kVCVT is performed by adopting the self-excitation method of FIG. 2.
The internal of fig. 3 is composed of an ammeter A and a second adjustable inductor L1, wherein the ammeter A can be used for measuring a high-voltage end, and can be used for detecting the total current of a circuit, so that the purpose of detecting the minimum total current when the first inductor L is adjusted in a test is to realize the parallel resonance of the circuit. The first inductor L changes the inductance through an inductance knob, and finally the parallel resonance effect is generated between the first inductor L and a target parallel path, and an equivalent circuit is arranged in the grounding shell.
Fig. 4 shows a dielectric loss connection of a first capacitor C11 of a testing 220kV CVT, which is based on the principle that when parallel resonance occurs in the parallel circuit of the inductor and the capacitor, the circuit is equivalent to an open circuit, and can be used to filter out a current signal with a certain frequency. The specific wiring is shown in fig. 4, at this time, the third capacitor C2, the second adjustable inductor L1 built in the device, and the first inductor L of the electromagnetic unit form a series-parallel circuit, and the branch z= (xl1+xc2)// XL has a condition that Z approaches infinity, i.e:
Z＝(jwX L1 +1/jwC 2 )//jwX L ＝jwX L /(1-w 2 C 2 L/(1-w 2 C 2 L 1 ))
to meet the condition
w 2 C 2 L＝1-w 2 C 2 L 1
L+L 1 ＝1/w 2 C 2
When the parallel resonance occurs in the branch, the total current of the circuit is minimum, according to the characteristic, when the current is minimum, the current flowing into the dielectric loss meter bridge is basically the current of the first capacitor C11, and the dielectric loss and the capacitance of the first capacitor C11 can be accurately measured by adjusting the knob and observing the ammeter A.
The point capacity of the third capacitor C2 at the lower part of the 220KV CVT is generally not more than 100nF, and the dielectric loss is generally 45HZ, 55HZ and 65HZ at the output frequency, so that the adjustable inductance of the device can meet the requirements within the range of 0-1000 uH.
Similarly, when the self-excitation method is adopted to measure the second capacitor C12 and the third capacitor C2, in order to prevent the first capacitor C11 from affecting the bridge, the knob may be adjusted according to the wiring method shown in fig. 2, so that when the total current of the circuit is minimum, the measurement result of the dielectric loss meter is the capacitance of the final second capacitor C12 and the third capacitor C2, and the requirement is satisfied at this time.
Because the first capacitance C11 is smaller than the third capacitance C2 and is generally not larger than 25nF, the adjustable inductance adjustable range of the device meets the requirement. In the test process, the instrument shell needs to be grounded, so that test safety is ensured.
The foregoing has shown and described the basic principles and main features of the present invention and the advantages of the present invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (7)
1. A dielectric loss measurement method of a 220KV voltage transformer lead wire without disassembly is characterized by comprising the following steps:
and (3) circuit connection: connecting the resonant circuit with the circuit to be detected in parallel, and connecting the equivalent circuit with the resonant circuit;
first capacitor (C11) current detection: rotating the inductance value knob, observing the value of an ammeter (A), stopping when the current is minimum, and recording the value as the current of a first capacitor (C11);
second capacitor (C12) and third capacitor (C2) current detection: rotating the inductance knob, and recording the current of the second capacitor (C12) and the third capacitor (C2) when the total current of the circuit is minimum;
the equivalent circuit comprises an ammeter (A) and a second adjustable inductor (L1);
when the current of the first capacitor (C11) is detected, the equivalent circuit is connected with the resonant circuit as follows: first electric capacity (C11), second electric capacity (C12) and third electric capacity (C2) and second adjustable inductance (L1) are established ties in proper order earlier to keep away from the one end of second electric capacity (C12) at first electric capacity (C11) and insert the power, first electric capacity (L) connects in parallel at third electric capacity (C2) and second adjustable inductance (L1) both ends, the one end of ampere meter (A) is connected between first electric capacity (C11) and second electric capacity (C12), and the other end inserts experimental high-voltage line.
2. The dielectric loss measurement method for the disassembly-free lead of the 220 kilovolt voltage transformer according to claim 1, wherein the dielectric loss measurement method is characterized by comprising the following steps of: the first inductor (L) comprises two groups of coils, one end of one coil is connected to a wire between the second capacitor (C12) and the third capacitor (C2), the other end of the other coil is connected with a power supply, and two ends of the other coil are connected through wires.
3. The dielectric loss measurement method for the disassembly-free lead of the 220 kilovolt voltage transformer according to claim 1, wherein the dielectric loss measurement method is characterized by comprising the following steps of: in the first capacitor (C11) current detection, the third capacitor (C2), the second adjustable inductor (L1) and the first inductor (L) form a series-parallel circuit, when the current is minimum, the branch z= (xl1+xc2)// XL, when the condition that the branch generates parallel resonance is that Z tends to infinity, namely:
Z＝(jwX L1 +1/jwC 2 )//jwX L ＝jwX L /(1-w 2 C 2 L/(1-w 2 C 2 L 1 ))
to satisfy the condition:
4. the dielectric loss measurement method for the disassembly-free lead of the 220 kilovolt voltage transformer according to claim 1, wherein the dielectric loss measurement method is characterized by comprising the following steps of: when the currents of the second capacitor (C12) and the third capacitor (C2) are detected, the equivalent circuit is connected with the resonant circuit as follows: the first capacitor (C11), the second capacitor (C12) and the third capacitor (C2) are sequentially connected in series, one end of the first capacitor (C11) far away from the second capacitor (C12) is connected into a power supply, one end of the second adjustable inductor (L1) in the equivalent circuit is connected between the first capacitor (C11) and the second capacitor (C12), the other end of the second adjustable inductor is connected with the power supply, and an ammeter (A) in the equivalent circuit is connected with the first inductor (L) in parallel.
5. The dielectric loss measurement method for the disassembly-free lead of the 220 kilovolt voltage transformer according to claim 4, wherein the dielectric loss measurement method is characterized by comprising the following steps of: the first inductor (L) comprises two groups of coils, one end of one coil is connected to a wire between the second capacitor (C12) and the third capacitor (C2), the other end of the coil is connected with a power supply, and two ends of the other coil are respectively connected with two ends of the ammeter (A).
6. The dielectric loss measurement method for the disassembly-free lead of the 220 kilovolt voltage transformer according to claim 1, wherein the dielectric loss measurement method is characterized by comprising the following steps of: the inductance value adjusting range of the third capacitor (C2) is 0-1000uH, and the outside of the equivalent circuit device is grounded.
7. The dielectric loss measurement method for the disassembly-free lead of the 220 kilovolt voltage transformer according to claim 5, wherein the dielectric loss measurement method is characterized by comprising the following steps of: in the detection of the currents of the second capacitor (C12) and the third capacitor (C2), when the total current of the circuit is minimum, L1=1/w 2 C11。
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