CN211528652U - Transformer state monitoring circuit and equipment - Google Patents
Transformer state monitoring circuit and equipment Download PDFInfo
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- CN211528652U CN211528652U CN201921667761.7U CN201921667761U CN211528652U CN 211528652 U CN211528652 U CN 211528652U CN 201921667761 U CN201921667761 U CN 201921667761U CN 211528652 U CN211528652 U CN 211528652U
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Abstract
The embodiment of the application discloses transformer state monitoring circuit and equipment, transformer state monitoring circuit includes: the output end of the signal conversion circuit is connected with the input end of the signal amplification circuit and used for converting a first current signal input to the signal conversion circuit into a first voltage signal, the output end of the signal amplification circuit is connected with the input end of the capacitance circuit, the output end of the capacitance circuit is connected with the input end of the voltage follower circuit and used for converting a second voltage signal into a third voltage signal, the third voltage signal does not include a voltage signal of a direct current component, and the output end of the voltage follower circuit is connected with the input end of the filter circuit.
Description
Technical Field
The application relates to the field of power systems, in particular to a transformer state monitoring circuit and equipment.
Background
In the operation of the transformer, the transformer core is insulated from other parts of the transformer, and the insulation state of the transformer can be monitored by detecting the grounding current of the transformer core, namely the leakage current of the transformer core to the ground. Therefore, how to detect the grounding current of the transformer core is a problem to be solved, and the insulation state of the transformer can be accurately and reliably monitored.
SUMMERY OF THE UTILITY MODEL
The embodiment of the application provides a transformer state monitoring circuit and equipment, which not only can amplify the current connected with the ground into a stable voltage signal, but also can acquire a voltage amplification result of an alternating current component in the current connected with the ground, so that the purpose of improving the sampling precision of the current connected with the ground is achieved.
In order to achieve the above purpose, the technical solution of the embodiment of the present application is implemented as follows:
in a first aspect, an embodiment of the present application provides a transformer state monitoring circuit, where the transformer state monitoring circuit includes: a signal conversion circuit, a signal amplification circuit, a capacitance circuit, a voltage follower circuit and a filter circuit, wherein,
the output end of the signal conversion circuit is connected with the input end of the signal amplification circuit and is used for converting a first current signal input to the signal conversion circuit into a first voltage signal;
the output end of the signal amplification signal circuit is connected with the input end of the capacitor circuit and is used for amplifying the first voltage signal into a second voltage signal;
the output end of the capacitor circuit is connected with the input end of the voltage follower circuit and is used for converting the second voltage signal into a third voltage signal, wherein the third voltage signal does not comprise a voltage signal of a direct-current component;
the output end of the voltage follower circuit is connected with the input end of the filter circuit and is used for improving the input impedance of the filter circuit and converting the third voltage signal into a fourth voltage signal;
and the filter circuit is used for carrying out filter processing on the fourth voltage signal.
In some embodiments, the transformer condition monitoring circuit further comprises: a transient suppression circuit, wherein,
the input end of the transient suppression circuit is connected with the output end of the sensor sampling circuit, and the output end of the transient suppression circuit is connected with the input end of the signal conversion circuit and used for suppressing the surge current signal in the first current signal.
In some embodiments, the Transient suppression circuit is a Transient Voltage Supply (TVS), wherein,
the first end of the TVS is connected with the input end of the signal conversion circuit, and the second end of the TVS is connected with the ground.
In some embodiments, the signal conversion circuit includes a first operational amplifier and a first resistor, wherein,
the inverting input end of the first operational amplifier is respectively connected with the first end of the TVS and the second end of the first resistor, the non-inverting input end of the first operational amplifier is connected with the ground, and the output end of the first operational amplifier is connected with the first end of the first resistor.
In some embodiments, the signal amplification circuit comprises a second operational amplifier, a second resistor, a third resistor;
the capacitance circuit comprises a first capacitance;
the voltage follower circuit includes a third operational amplifier and a fourth resistor, wherein,
the inverting input end of the second operational amplifier is connected with the first end of the second resistor, the second end of the second resistor is connected with the output end of the signal conversion circuit, the non-inverting input end of the second operational amplifier is connected with the ground, the output end of the second operational amplifier is connected with the first end of the third resistor, and the second end of the third resistor is connected with the inverting input end of the second operational amplifier;
a first end of the first capacitor is connected with an output end of the second operational amplifier, and a second end of the first capacitor is respectively connected with a positive phase input end of the third operational amplifier and a first end of the fourth resistor;
a positive phase input end of the third operational amplifier is respectively connected with a first end of the fourth resistor and a second end of the first capacitor, a second end of the fourth resistor is connected with the ground, and an output end of the third operational amplifier is connected with an inverting input end of the third operational amplifier;
and the output end of the third operational amplifier is connected with the input end of the filter circuit.
In some embodiments, the filter circuit is a 4 th order low pass active filter circuit; wherein the content of the first and second substances,
the 4-order low-pass active filter circuit comprises a first 2-order active filter circuit and a second 2-order active filter circuit.
In some embodiments, an output terminal of the voltage follower circuit is connected to an input terminal of the first 2 nd order active filter circuit, and an output terminal of the first 2 nd order active filter circuit is connected to an input terminal of the second 2 nd order active filter circuit.
In some embodiments, the first 2 nd order active filter circuit comprises a fourth operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor, a second capacitor, and a third capacitor; the second 2 nd order active filter circuit comprises a fifth operational amplifier, an eighth resistor, a ninth resistor, a fourth capacitor and a fifth capacitor.
In some embodiments, a first terminal of the fifth resistor is connected to the output terminal of the voltage follower circuit, a second terminal of the fifth resistor is connected to a first terminal of the sixth resistor, and a second terminal of the sixth resistor is connected to the non-inverting input terminal of the fourth operational amplifier;
a positive phase input end of the fourth operational amplifier is connected with a first end of the second capacitor, a second end of the second capacitor is connected with the ground, an inverted phase input end of the fourth operational amplifier is respectively connected with an output end of the fourth operational amplifier and a first end of the seventh resistor, an output end of the fourth operational amplifier is respectively connected with a first end of the third capacitor and a first end of the eighth resistor, and a second end of the third capacitor is connected with a first end of the sixth resistor;
the second end of the eighth resistor is connected with the first end of the ninth resistor, the second end of the ninth resistor is connected with the positive phase input end of the fifth operational amplifier, the positive phase input end of the fifth operational amplifier is connected with the first end of the fourth capacitor, the second end of the fourth capacitor is connected with the ground, the inverting input end of the fifth operational amplifier is connected with the output end of the fifth operational amplifier, the output end of the fifth operational amplifier is connected with the first end of the fifth capacitor, and the second end of the fifth capacitor is connected with the first end of the ninth resistor and the second end of the eighth resistor respectively.
In a second aspect, the present embodiments provide an apparatus for a transformer state monitoring circuit, the apparatus comprising the transformer state monitoring circuit according to the first aspect, a sensor sampling circuit, and a peripheral circuit, wherein,
the sensor sampling circuit is used for collecting the grounding current signal of the transformer core;
the transformer state monitoring circuit is connected with the output end of the sensor sampling circuit and is used for converting the transformer grounding current signal into a voltage signal;
and the peripheral circuit is connected with the output end of the transformer state monitoring circuit and is used for processing the voltage signal output by the transformer state monitoring circuit and displaying the processed voltage signal.
The embodiment of the application provides a transformer state monitoring circuit, transformer state monitoring circuit includes: the circuit comprises a signal conversion circuit, a signal amplification circuit, a capacitor circuit, a voltage follower circuit and a filter circuit, wherein the output end of the signal conversion circuit is connected with the input end of the signal amplification circuit and is used for converting a first current signal input to the signal conversion circuit into a first voltage signal; the output end of the signal amplification signal circuit is connected with the input end of the capacitor circuit and is used for amplifying the first voltage signal into a second voltage signal; the output end of the capacitor circuit is connected with the input end of the voltage follower circuit and is used for converting the second voltage signal into a third voltage signal, wherein the third voltage signal does not comprise a voltage signal of a direct-current component; the output end of the voltage follower circuit is connected with the input end of the filter circuit and is used for improving the input impedance of the filter circuit and converting the third voltage signal into a fourth voltage signal; and the filter circuit is used for carrying out filter processing on the fourth voltage signal. So, the realization carries out current/voltage conversion with the little electric current of sensor sampling circuit collection, enlargies and filtering process, interference signal in the effective filtering signal, thereby obtain a stable output voltage signal, and obtain the voltage amplification result with the alternating current component in the earth connecting current alone through capacitor circuit, thereby improve the sampling precision of ground current, and then make the reliability and the accuracy of the insulating condition monitoring device of transformer obtain improving greatly, maintain to provide the powerful basis of judging for the operation, effectively prevent the accident range that transformer equipment damage caused and enlarge.
Drawings
Fig. 1 is a schematic structural diagram of a transformer state monitoring circuit according to an embodiment of the present disclosure;
FIG. 2 is a schematic diagram of a transformer state monitoring circuit according to another embodiment of the present disclosure;
FIG. 3 is a schematic diagram illustrating a filter circuit according to an embodiment of the present disclosure;
FIG. 4 is a schematic diagram of an electronic device structure of a transformer status monitoring circuit according to an embodiment of the present disclosure;
FIG. 5 is a schematic diagram of an electronic device of a transformer status monitoring circuit according to another embodiment of the present disclosure;
fig. 6 is a schematic structural diagram of a transformer state monitoring device according to another embodiment of the present application.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, specific technical solutions of the present invention will be described in further detail below with reference to the accompanying drawings in the embodiments of the present application. The following examples are intended to illustrate the present application but are not intended to limit the scope of the present application.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.
When the transformer normally operates, the iron core and the box body are insulated, the iron core and other grounding parts of the transformer are also insulated, and the iron core is grounded only a little. However, when the insulation of the transformer core is poor or the transformer core is connected with the ground in multiple points, current can be generated in the core and generate heat, the heat generated by the core can cause the insulation oil of the transformer to be decomposed, combustible gas ethylene is generated, acetylene can be generated in severe cases, and even a winding can be burnt. Therefore, the insulation state of the transformer can be monitored in real time by monitoring the leakage current of the transformer iron core to the ground in real time, the insulation degradation rate of the transformer iron core is reflected, and a basis is provided for the condition maintenance of the transformer.
In the insulation state monitoring of the transformer, although the leakage current of the transformer core is collected by the sensor sampling circuit, the leakage current of the transformer core is relatively small and unstable, and cannot be directly analyzed or the accuracy of analysis is low, so that the reliability of detecting the insulation state of the transformer is low.
In an aspect of the present embodiment, a transformer state monitoring circuit is provided, referring to fig. 1, where the transformer state monitoring circuit 102 includes: a signal conversion circuit 1021, a signal amplification circuit 1022, a capacitance circuit 1023, a voltage follower circuit 1024, and a filter circuit 1025.
An output end of the signal conversion circuit 1021 is connected to an input end of the signal amplification circuit 1022, and is configured to convert the first current signal input to the signal conversion circuit into a first voltage signal. Here, an input terminal of the signal conversion circuit 1021 is connected to an input terminal of the sensor sampling circuit 101, and converts the first current signal collected by the sensor sampling circuit 101 into a first voltage signal.
The output terminal of the signal amplifying circuit 1022 is connected to the input terminal of the capacitor circuit 1023, and is used for amplifying the first voltage signal into a second voltage signal. Here, since the first current signal is converted into the first voltage signal by the signal conversion circuit 1021, the first voltage signal is small, which is not favorable for signal analysis. The signal amplification circuit 1022 is connected to the output terminal of the signal conversion circuit 1021, and the signal amplification circuit 1022 amplifies the first voltage signal into the second voltage signal.
An output terminal of the capacitor circuit 1023 is connected to an input terminal of the voltage follower circuit 1024 for converting the second voltage signal into a third voltage signal, wherein the third voltage signal does not include a voltage signal of a dc component.
Here, since the first current signal collected by the sensor sampling circuit 101 includes a current signal of an ac component and a current signal of a dc component, the signal conversion circuit 1021 and the signal amplification signal circuit 1022 convert the current signal of the ac component and the current signal of the dc component into a voltage signal of an ac component and a voltage signal of a dc component, and amplify the voltage signal of the ac component and the voltage signal of the dc component, but a mixed voltage signal including the amplified ac component and the amplified dc component may affect the sampling accuracy of the output of the transformer state monitoring circuit. Therefore, by connecting the capacitance circuit 1023 to the signal amplification circuit 1022, the second voltage signal is converted into a third voltage signal without a dc component, so as to obtain a voltage signal of an ac component, isolate the voltage signal of the dc component, and improve sampling accuracy.
The output end of the voltage follower circuit 1024 is connected to the input end of the filter circuit 1025, and is configured to increase the input impedance of the filter circuit 1025 and convert the third voltage signal into a fourth voltage signal.
Here, since the output impedance of the signal amplification circuit 1022 is high, the voltage follower circuit 1024 is employed to increase the input impedance of the filter circuit 1025, thereby improving the accuracy of the amplification circuit. The voltage follower circuit 1024 performs impedance transformation, and the third voltage signal input by the input terminal of the voltage follower circuit 1024 is equal to or slightly smaller than the fourth voltage signal output by the output terminal of the voltage follower circuit 1024.
And the filter circuit 1025 is used for filtering the fourth voltage signal.
Here, since the earth connection current of the transformer core may include a high-frequency current, the earth connection current passes through the signal conversion circuit 1021, the signal amplification circuit 1022, the capacitor circuit 1023, and the voltage follower circuit 1024 to obtain a fourth voltage signal of the amplified ac component, where the fourth voltage signal includes an interference signal, and thus the filter circuit 1025 is connected to an output terminal of the voltage follower circuit 1024, and the filter circuit 1025 filters the fourth voltage signal including the interference signal to finally obtain a voltage signal of a desired frequency band.
In the above embodiment, the transformer status monitoring circuit 102 includes: a signal conversion circuit 1021, a signal amplification circuit 1022, a capacitance circuit 1023, a voltage follower circuit 1024, and a filter circuit 1025. So, realize carrying out electric current/voltage conversion, amplification and filtering with the little electric current of sensor sampling circuit collection, effectively filtering the interfering signal in the signal to obtain a stable output voltage signal, and obtain the voltage amplification result with the alternating current component in the earth connecting current alone, thereby improve the sampling precision with earth connecting current, and then make the insulating condition monitoring devices' of transformer reliability and accuracy obtain improving greatly.
In some embodiments, referring to fig. 2, the transformer status monitoring circuit 102 further includes: a transient suppression circuit 1026.
The input end of the transient suppression circuit 1026 is connected to the output end of the sensor sampling circuit 101, and the output end of the transient suppression circuit 1026 is connected to the input end of the signal conversion circuit 1021, so as to suppress the inrush current signal in the first current signal.
Here, the first current signal output from the sensor sampling circuit 101 may include an inrush current signal that may damage elements constituting the transformer state monitoring circuit, and thus the transient suppression circuit 1026 is provided between the sensor sampling circuit 101 and the signal conversion circuit 1021 to suppress the inrush current signal in the first current signal and protect the elements of the transformer state monitoring circuit.
In some embodiments, referring to fig. 3, the filter circuit 1025 is a 4-step low-pass active filter circuit; wherein the content of the first and second substances,
the 4-order low-pass active filter circuit comprises a first 2-order active filter circuit 201 and a second 2-order active filter circuit 202.
In some embodiments, the output terminal of the voltage follower circuit 1024 is connected to the input terminal of the first 2 nd order active filter circuit 201, and the output terminal of the first 2 nd order active filter circuit 201 is connected to the input terminal of the second 2 nd order active filter circuit 202.
In the above embodiment, the filter circuit 1025 adopts a 4-order low-pass active filter circuit, and the 4-order low-pass active filter circuit is composed of 2-order active filter circuits, so that a low-cost filter circuit is formed, and an interference signal is effectively filtered.
It should be noted that the two operational amplifiers used in the embodiment of the present application are controlled by one operational amplifier chip, that is, the operational amplifier chip used in the embodiment of the present application is a single-chip dual-operational amplifier chip, wherein the first operational amplifier U10A and the second operational amplifier U10B are controlled by one chip, and the third operational amplifier U11B and the fourth operational amplifier U11A are controlled by another chip, so that the first operational amplifier U10A and the second operational amplifier U10B share a positive power supply and a negative power supply, and the third operational amplifier U11B and the fourth operational amplifier U11A share a positive power supply and a negative power supply, so that in fig. 4, neither the second operational amplifier U10B nor the third operational amplifier U11B identify the positive and negative power supplies to which the operational amplifiers are connected.
In another aspect of the present embodiment, referring to fig. 4, another transformer state monitoring circuit is provided, in which the transformer state monitoring circuit 102 includes: the circuit comprises a signal conversion circuit 1021, a signal amplification circuit 1022, a capacitance circuit 1023, a voltage follower circuit 1024 and a filter circuit 1025, wherein the signal conversion circuit 1021 comprises a first operational amplifier U10A and a first resistor R57.
The signal conversion circuit 1021 comprises a first operational amplifier U10A and a first resistor R57, wherein the first operational amplifier U10A is a dual-power operational amplifier, the positive pole of the power supply is connected to +12V voltage, and the negative pole of the power supply is connected to-12V voltage. The output end of the first operational amplifier U10A is connected to the output end of the signal amplifying circuit 1022, the output end of the first operational amplifier U10A is further connected to its own inverting input end through a first resistor R57, the inverting input end of the first operational amplifier U10A is connected to the output end of the transient suppression circuit, and the non-inverting input end of the first operational amplifier U10A is connected to the ground.
In the above embodiment, the transformer status monitoring circuit 102 includes: a signal conversion circuit 1021, a signal amplification circuit 1022, a capacitance circuit 1023, a voltage follower circuit 1024, and a filter circuit 1025. So, realize carrying out electric current/voltage conversion, amplification and filtering with the little electric current of sensor sampling circuit collection, effectively filtering the interfering signal in the signal to obtain a stable output voltage signal, and obtain the voltage amplification result with the alternating current component in the earth connecting current alone, thereby improve the sampling precision with earth connecting current, and then make the insulating condition monitoring devices' of transformer reliability and accuracy obtain improving greatly. In addition, a signal conversion circuit formed by the first operational amplifier U10A and the first resistor R57 can convert the current signal into a voltage signal meeting a certain relation, and a user can conveniently monitor the grounding current condition of the transformer core.
In some embodiments, referring to fig. 5, the transformer status monitoring circuit 102 further includes: a Transient suppression circuit 1026, wherein the Transient suppression circuit 1026 is a Transient Voltage Super (TVS).
The first terminal of the TVS is connected to the input terminal of the signal conversion circuit 1021, and the second terminal of the TVS is connected to ground.
Specifically, the inverting input terminal of the first operational amplifier U10A is connected to the first terminal of the TVS and the second terminal of the first resistor R57, respectively, the non-inverting input terminal of the first operational amplifier U10A is connected to ground, and the output terminal of the first operational amplifier U10A is connected to the first terminal of the first resistor R57.
Here, a first terminal of the TVS is connected to the sensor sampling circuit input terminal and the inverting input terminal of the first operational amplifier U10A, respectively, and a second terminal of the TVS is connected to ground. When surge current appears in a first current signal TRS output by a sensor sampling circuit, the TVS is turned on when the first current signal TRS exceeds rated current, the first current signal TRS flows to the TVS, and the surge current is released to the ground, so that the TVS inhibits the surge current in the first current signal TRS, and elements of the circuit are prevented from being damaged by the surge current.
In some embodiments, referring to fig. 4 and 5, the signal amplifying circuit 1022 includes a second operational amplifier U10B, a second resistor R60, a third resistor R58 and R59.
The capacitance circuit 1023 comprises a first capacitance C68.
The voltage follower circuit 1024 includes a third operational amplifier U11B and a fourth resistor R66, wherein,
an inverting input terminal of the second operational amplifier U10B is connected to a first terminal of the second resistor R60, a second terminal of the second resistor R60 is connected to an output terminal of the signal conversion circuit 1021, a non-inverting input terminal of the second operational amplifier U10B is connected to ground, an output terminal of the second operational amplifier U10B is connected to first terminals of the third resistors R58 and R59, and second terminals of the third resistors R58 and R59 are connected to an inverting input terminal of the second operational amplifier U10B.
Here, the second operational amplifier U10B is a dual-power operational amplifier, a positive electrode of a power supply is connected to a voltage of +12V, a negative electrode of the power supply is connected to a voltage of-12V, an inverting input terminal of the second operational amplifier U10B is connected to an output terminal of the signal conversion circuit 1021 through a second resistor R60, the inverting input terminal is further connected to ground, an output terminal of the second operational amplifier U10B is electrically connected to an input terminal of the voltage follower circuit 1024 through a first capacitor C68, an output terminal of the second operational amplifier U10B is further connected to an inverting input terminal of the second operational amplifier U10B through third resistors R59 and R58 in sequence, that is, the inverting input terminal of the second operational amplifier U10B is connected to a node between the second resistor R60 and the third resistors R59 and R58.
The third resistors R59 and R58 and the second resistor R60 form negative feedback, and the amplification factor of the signal amplification circuit 1022 satisfies the following formula (1):
wherein A isVSThe amplification factor of the signal amplification circuit 1022 can be adjusted by adjusting the magnitudes of the R58, R59, and R60 parameters for the amplification factor of the amplification circuit. For example, R58 is a resistor of 10 kilo-ohms, R58 is a resistor of 2.7 kilo-ohms, R60 is a resistor of 10 kilo-ohms, and the amplification factor of the signal amplification circuit 1022 is 2.27 times, that is, the voltage signal is amplified by 2.27 times after passing through the signal amplification circuit 1022.
It should be noted that, the third resistor may adopt an adjustable resistor, so as to flexibly change the amplification factor of the signal amplification circuit 1022 according to the requirement.
A first end of the first capacitor C68 is connected to the output end of the second operational amplifier U10B, and a second end of the first capacitor C68 is connected to the non-inverting input end of the third operational amplifier U11B and a first end of the fourth resistor R66, respectively.
Here, the first capacitor C68 isolates the voltage signal of the dc component in the amplified voltage signal output by the signal amplification circuit 1022, and the voltage signal of the ac component is obtained, which improves the sampling accuracy.
A non-inverting input terminal of the third operational amplifier U11B is connected to a first terminal of the fourth resistor R66 and a second terminal of the first capacitor C68, respectively, a second terminal of the fourth resistor R66 is connected to ground, and an output terminal of the third operational amplifier U11B is connected to an inverting input terminal of the third operational amplifier U11B.
The output terminal of the third operational amplifier U11B is connected to the input terminal of the filter circuit 1025.
Here, the non-inverting input terminal of the third operational amplifier U11B is connected to the first terminal of the fourth resistor R66 and the second terminal of the first capacitor C68, respectively, which means that the non-inverting input terminal of the third operational amplifier U11B is connected to the first terminal of the fourth resistor R66, and the non-inverting input terminal of the third operational amplifier U11B is further connected to the second terminal of the first capacitor C68, i.e., the non-inverting input terminal of the third operational amplifier U11B is connected to a node between the first capacitor C68 and the fourth resistor R66.
In the above embodiment, the signal amplifying circuit 1022 is connected to the voltage follower circuit 1024 through the first capacitor C68, so that the voltage signal of the dc component in the amplified voltage signal passing through the signal amplifying circuit 1022 is isolated by the first capacitor C68, and the voltage signal of the ac component in the amplified voltage signal is input to the voltage follower circuit 1024, thereby improving the sampling accuracy. In addition, the input impedance of the filter circuit 1025 is improved by the voltage follower circuit 1024, thereby improving the accuracy of the amplifying circuit.
In some embodiments, referring to fig. 4 and 5, the filter circuit 1025 is a 4-step low-pass active filter circuit; the 4-order low-pass active filter circuit comprises a first 2-order active filter circuit and a second 2-order active filter circuit, and the first 2-order active filter circuit 201 comprises a fourth operational amplifier U11A, a fifth resistor R61, a sixth resistor R62, a seventh resistor R63, a second capacitor C69 and a third capacitor C66; the second 2 nd order active filter circuit 202 includes a fifth operational amplifier U12A, an eighth resistor R64, a ninth resistor R65, a fourth capacitor C70, and a fifth capacitor C67.
A first end of the fifth resistor R61 is connected to the output end of the voltage follower circuit 1024, a second end of the fifth resistor R61 is connected to a first end of the sixth resistor R62, and a second end of the sixth resistor R62 is connected to the non-inverting input end of the fourth operational amplifier.
A positive input terminal of the fourth operational amplifier is connected to the first terminal of the second capacitor, a second terminal of the second capacitor is connected to ground, an inverting input terminal of the fourth operational amplifier U11A is connected to an output terminal of the fourth operational amplifier U11A and the first terminal of the seventh resistor R63, an output terminal of the fourth operational amplifier U11A is connected to the first terminal of the third capacitor C66 and the first terminal of the eighth resistor R64, and a second terminal of the third capacitor C66 is connected to the first terminal of the sixth resistor R62.
Here, the fourth operational amplifier U11A is a dual-power operational amplifier, the positive electrode of the power supply is connected to +12V voltage, the negative electrode of the power supply is connected to-12V voltage, the output terminal of the voltage follower circuit 1024 is connected to the positive input terminal of the fourth operational amplifier U11A through a fifth resistor R61 and a sixth resistor R62 in sequence, the positive input terminal of the fourth operational amplifier U11A is further connected to the ground through a second capacitor C69, the output terminal of the fourth operational amplifier U11A is connected to the input terminal of the second 2-step low-pass active filter through a seventh resistor R63, the output terminal of the fourth operational amplifier U11A is further connected to a node between the fifth resistor R61 and the sixth resistor R62 through a third capacitor C66, and the output terminal of the fourth operational amplifier U11A is further electrically connected to the inverting input terminal of the fourth operational amplifier U11A.
A second end of the eighth resistor R64 is connected to a first end of the ninth resistor R65, a second end of the ninth resistor R65 is connected to a non-inverting input terminal of the fifth operational amplifier U12A, a non-inverting input terminal of the fifth operational amplifier U12A is connected to a first end of the fourth capacitor C70, a second end of the fourth capacitor C70 is connected to ground, an inverting input terminal of the fifth operational amplifier U12A is connected to an output terminal of the fifth operational amplifier U12A, an output terminal of the fifth operational amplifier U12A is connected to a first end of the fifth capacitor C67, and a second end of the fifth capacitor C67 is connected to a first end of the ninth resistor R65 and a second end of the eighth resistor R64, respectively.
Here, the fifth operational amplifier U12A is a dual-power operational amplifier, the positive power supply terminal thereof is connected to +12V voltage, the negative power supply terminal thereof is connected to-12V voltage, the output terminal of the first 2 nd order low-pass active filter circuit is connected to the positive input terminal of the fifth operational amplifier U12A through an eighth resistor R64 and a ninth resistor R65 in sequence, the positive input terminal of the fifth operational amplifier U12A is further connected to the ground through a fourth capacitor C70, the output terminal of the fifth operational amplifier U12A is connected to the node between the eighth resistor R64 and the ninth resistor R65 through a fifth capacitor C67, and the output terminal of the fifth operational amplifier U12A is further electrically connected to the negative input terminal of the fifth operational amplifier U12A.
For example, the fifth resistor R61 is a 3.3 kilo-ohm resistor, the sixth resistor R62 is a 2 kilo-ohm resistor, the second capacitor C69 is a 100-nanofarad capacitor, the third capacitor C66 is a 470-nanofarad capacitor, the seventh resistor R63 is a 10 kilo-ohm resistor, the eighth resistor R64 is a 1 kilo-ohm resistor, the ninth resistor R65 is a 6.2 kilo-ohm resistor, the fifth capacitor C67 is a 150-nanofarad capacitor, and the fourth capacitor C70 is a 100-nanofarad capacitor, and the passband cutoff frequency of the 4-step low-pass active filter circuit composed of the above elements is 900HZ to 1200 HZ.
In the above embodiment, 2-order active filter circuits constitute a 4-order active filter circuit, thereby constituting a low-cost filter circuit and effectively filtering interference signals.
In another aspect, a transformer state monitoring apparatus is provided, referring to fig. 6, the apparatus includes a transformer state monitoring circuit 102, a sensor sampling circuit 101 and a peripheral circuit 103 according to any of the embodiments of the present disclosure, wherein,
and the sensor sampling circuit 101 is used for acquiring the grounding current signal of the transformer core.
Here, the sensor sampling circuit 101 includes a feedthrough current sensor that collects a micro-current signal of the transformer core grounded.
The transformer state monitoring circuit 102 is connected to the output end of the sensor sampling circuit 101, and is configured to convert the transformer ground current signal into a voltage signal.
The peripheral circuit 103 is connected to the output end of the transformer state monitoring circuit 102, and is configured to process the voltage signal output by the transformer state monitoring circuit 102 and display the processed voltage signal.
Here, the peripheral circuit 103 includes an analog-to-digital conversion circuit, and/or a display circuit, and/or a wireless transmission circuit. The analog-to-digital conversion circuit is configured to convert an analog voltage signal output by the transformer state monitoring circuit 102 into a digital voltage signal, which is convenient for front-end display. The display circuit is used for displaying the output voltage signal. The wireless transmitting circuit is used for transmitting the voltage signal output by the transformer state monitoring circuit 102 to external equipment, so that the transformer core grounding current can be remotely monitored conveniently.
It will be understood by those of ordinary skill in the art that all or some of the steps of the methods, systems, functional modules/units in the devices disclosed above may be implemented as software, firmware, hardware, and suitable combinations thereof. In a hardware implementation, the division between functional modules/units mentioned in the above description does not necessarily correspond to the division of physical components; for example, one physical component may have multiple functions, or one function or step may be performed by several physical components in cooperation. Some or all of the physical components may be implemented as software executed by a processor, such as a central processing unit, digital signal processor, or microprocessor, or as hardware, or as an integrated circuit, such as an application specific integrated circuit.
The above description is only for the specific embodiments of the present application, but the scope of the present application is not limited thereto, and any person skilled in the art can easily conceive of the changes or substitutions within the technical scope of the present application, and shall be covered by the scope of the present application. The protection scope of the present application shall be subject to the protection scope of the claims.
Claims (10)
1. A transformer condition monitoring circuit, the transformer condition monitoring circuit comprising: the circuit comprises a signal conversion circuit, a signal amplification circuit, a capacitor circuit, a voltage follower circuit and a filter circuit, wherein the output end of the signal conversion circuit is connected with the input end of the signal amplification circuit and is used for converting a first current signal input to the signal conversion circuit into a first voltage signal;
the output end of the signal amplification circuit is connected with the input end of the capacitor circuit and is used for amplifying the first voltage signal into a second voltage signal;
the output end of the capacitor circuit is connected with the input end of the voltage follower circuit and is used for converting the second voltage signal into a third voltage signal, and the third voltage signal does not comprise a voltage signal of a direct-current component;
the output end of the voltage follower circuit is connected with the input end of the filter circuit and is used for improving the input impedance of the filter circuit and converting the third voltage signal into a fourth voltage signal;
and the filter circuit is used for carrying out filter processing on the fourth voltage signal.
2. The transformer condition monitoring circuit of claim 1, further comprising: a transient suppression circuit, wherein,
the input end of the transient suppression circuit is connected with the output end of the sensor sampling circuit, and the output end of the transient suppression circuit is connected with the input end of the signal conversion circuit and used for suppressing the surge current signal in the first current signal.
3. The transformer condition monitoring circuit of claim 2, wherein the transient suppression circuit is a transient suppression diode (TVS), wherein,
the first end of the TVS is connected with the input end of the signal conversion circuit, and the second end of the TVS is connected with the ground.
4. The transformer condition monitoring circuit of claim 3, wherein the signal conversion circuit comprises a first operational amplifier and a first resistor, wherein,
the inverting input end of the first operational amplifier is respectively connected with the first end of the TVS and the second end of the first resistor, the non-inverting input end of the first operational amplifier is connected with the ground, and the output end of the first operational amplifier is connected with the first end of the first resistor.
5. The transformer state monitoring circuit of claim 1, wherein the signal amplification circuit comprises a second operational amplifier, a second resistor, and a third resistor;
the capacitance circuit comprises a first capacitance;
the voltage follower circuit includes a third operational amplifier and a fourth resistor, wherein,
the inverting input end of the second operational amplifier is connected with the first end of the second resistor, the second end of the second resistor is connected with the output end of the signal conversion circuit, the non-inverting input end of the second operational amplifier is connected with the ground, the output end of the second operational amplifier is connected with the first end of the third resistor, and the second end of the third resistor is connected with the inverting input end of the second operational amplifier;
a first end of the first capacitor is connected with an output end of the second operational amplifier, and a second end of the first capacitor is respectively connected with a positive phase input end of the third operational amplifier and a first end of the fourth resistor;
a positive phase input end of the third operational amplifier is respectively connected with a first end of the fourth resistor and a second end of the first capacitor, a second end of the fourth resistor is connected with the ground, and an output end of the third operational amplifier is connected with an inverting input end of the third operational amplifier;
and the output end of the third operational amplifier is connected with the input end of the filter circuit.
6. The transformer condition monitoring circuit of claim 1, wherein the filter circuit is a 4 th order low pass active filter circuit; wherein the content of the first and second substances,
the 4-order low-pass active filter circuit comprises a first 2-order active filter circuit and a second 2-order active filter circuit.
7. The transformer condition monitoring circuit of claim 6, wherein the output of the voltage follower circuit is connected to the input of the first 2 nd order active filter circuit, and the output of the first 2 nd order active filter circuit is connected to the input of the second 2 nd order active filter circuit.
8. The transformer condition monitoring circuit of claim 6, wherein the first 2 nd order active filter circuit comprises a fourth operational amplifier, a fifth resistor, a sixth resistor, a seventh resistor, a second capacitor, and a third capacitor; the second 2 nd order active filter circuit comprises a fifth operational amplifier, an eighth resistor, a ninth resistor, a fourth capacitor and a fifth capacitor.
9. The transformer condition monitoring circuit of claim 8,
a first end of the fifth resistor is connected with an output end of the voltage follower circuit, a second end of the fifth resistor is connected with a first end of the sixth resistor, and a second end of the sixth resistor is connected with a non-inverting input end of the fourth operational amplifier;
a positive phase input end of the fourth operational amplifier is connected with a first end of the second capacitor, a second end of the second capacitor is connected with the ground, an inverted phase input end of the fourth operational amplifier is respectively connected with an output end of the fourth operational amplifier and a first end of the seventh resistor, an output end of the fourth operational amplifier is respectively connected with a first end of the third capacitor and a first end of the eighth resistor, and a second end of the third capacitor is connected with a first end of the sixth resistor;
the second end of the eighth resistor is connected with the first end of the ninth resistor, the second end of the ninth resistor is connected with the positive phase input end of the fifth operational amplifier, the positive phase input end of the fifth operational amplifier is connected with the first end of the fourth capacitor, the second end of the fourth capacitor is connected with the ground, the inverting input end of the fifth operational amplifier is connected with the output end of the fifth operational amplifier, the output end of the fifth operational amplifier is connected with the first end of the fifth capacitor, and the second end of the fifth capacitor is connected with the first end of the ninth resistor and the second end of the eighth resistor respectively.
10. A transformer condition monitoring device, comprising a transformer condition monitoring circuit according to any one of claims 1-9, a sensor sampling circuit, and a peripheral circuit,
the sensor sampling circuit is used for collecting a grounding current signal of the transformer core;
the transformer state monitoring circuit is connected with the output end of the sensor sampling circuit and is used for converting a transformer grounding current signal into a voltage signal;
and the peripheral circuit is connected with the output end of the transformer state monitoring circuit and is used for processing the voltage signal output by the transformer state monitoring circuit and displaying the processed voltage signal.
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| CN201921667761.7U CN211528652U (en) | 2019-09-30 | 2019-09-30 | Transformer state monitoring circuit and equipment |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115097197A (en) * | 2022-07-06 | 2022-09-23 | 中国华能集团清洁能源技术研究院有限公司 | Auxiliary circuit of current sensor and current sensor |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN115097197A (en) * | 2022-07-06 | 2022-09-23 | 中国华能集团清洁能源技术研究院有限公司 | Auxiliary circuit of current sensor and current sensor |
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