Transformer winding state on-line monitoring device based on high-frequency excitation and signal perception

Abstract

A transformer winding state on-line monitoring device based on high-frequency excitation and signal perception mainly comprises a high-frequency excitation injection module, a high-frequency signal perception module, a signal acquisition module and a computer, and the high-frequency signal perception module comprises a high-frequency mutual inductor and a signal detection amplification circuit. High-frequency excitation is injected into the low-voltage winding through the high-frequency excitation injection module, and sensing of current response signals of the low-voltage winding and the high-voltage winding of the transformer is achieved through the high-frequency signal sensing module. On-line monitoring of the state of the transformer winding is achieved, and an evaluation method and tool are provided for on-line monitoring of the early fault state of the transformer winding.

Description

Technical Field

[0001] The present invention belongs to the field of online monitoring of transformer winding status, and in particular relates to an online sensing device and a testing method for transformer winding response signals under high-frequency excitation. Background Art

[0002] When the frequency injected into the transformer is greater than 1kHz, the transformer winding can be regarded as a passive linear two-port network composed of resistors, inductors, and capacitors. When the transformer winding is deformed, short-circuited, or other faults occur, its electrical network parameters will change, and the changes in electrical parameters caused by different fault conditions will also be different, which will cause the response signal of the transformer winding to change. Therefore, by comparing and analyzing the frequency response characteristics before and after the winding fault, the winding fault diagnosis can be effectively performed. However, the frequency response can only be applied to the offline operation of the transformer. When the winding undergoes slight abnormal changes during long-term operation, untimely monitoring will lead to aggravated alienation and then failure. In order to address this deficiency, it is of great significance to carry out research that can perform online monitoring of the winding status. Summary of the invention

[0003] In order to overcome the shortcomings of the above background, the present invention provides a development and testing method of a transformer winding state online monitoring device based on high-frequency excitation and signal perception, including the following contents:

[0004] A transformer winding state online monitoring device based on high-frequency excitation and signal perception, characterized in that it comprises a high-frequency excitation injection module (1), a high-frequency signal perception module (2) and a signal acquisition module (3), wherein the high-frequency excitation injection module (1) generates a high-frequency square wave signal and injects it into the transformer winding through a low-voltage winding (4) lead wire, the high-frequency signal perception module (2) is sleeved on the low-voltage winding (4) and high-voltage winding (5) lead wires, and amplifies the sensed signal, and the signal acquisition module (3) transmits the processed signal to a computer (6), thereby realizing effective perception of the excitation signal and the response signal;

[0005] The high-frequency excitation injection module (1) includes a bridge rectifier circuit, specifically including four high-frequency diodes D connected in a specific manner, an output end connected in parallel to a filter capacitor C1, and then connected to a full-bridge inverter circuit, specifically including four high-frequency triodes T connected in a specific manner, wherein a control signal of the full-bridge inverter circuit is remotely controlled by a computer (6), thereby realizing remote control of the high-frequency excitation injection module (1);

[0006] The high-frequency signal sensing module (2) includes a high-frequency current transformer (7), specifically including an open-type nickel-zinc ferrite magnetic ring (8) and a housing fixing device (9). The output end of the transformer is connected to a modulation circuit (10) including a current-voltage conversion circuit and a signal amplification circuit. The current-voltage conversion circuit includes an operational amplifier U1, a conversion resistor R1 and an anti-parallel diode D T , the signal amplifying circuit includes an operational amplifier U2 and amplifying resistors R2 and R3;

[0007] The signal acquisition module (3) comprises an AD7606 acquisition chip, which can convert analog signals into high-precision digital signals. Its input end is connected to a signal amplification circuit, and its output end is connected to a computer (6) via a USB transmission line, so as to achieve effective acquisition of excitation signals and response signals.

[0008] The present invention also aims to provide a testing method for the above device, and its specific measures are:

[0009] A method for online monitoring of transformer winding status based on high-frequency excitation and signal perception, using the above-mentioned device to perform transformer winding high-frequency signal injection and perception testing, is characterized in that it includes the following steps:

[0010] The first step is to put a high-frequency signal sensing module (2) on the lead-out wires of the high-voltage winding (5) and the low-voltage winding (4), connect the output of the high-frequency signal sensing module (2) to the signal acquisition module (3), connect the signal acquisition module (3) to the computer (6) via a data line, and remotely connect the high-frequency excitation injection module (1) to the computer (6);

[0011] Step 2: Using a computer (6) to send instructions to a high-frequency excitation injection module (1), the high-frequency excitation injection module (1) injects a square wave signal with an amplitude of 20V and a frequency of f=100kHz into the transformer low-voltage winding (4), and transmits the sensed high-frequency signal to the computer (6) via the high-frequency signal sensing module (2) and the signal acquisition module (3) on the lead wires between the low-voltage winding (4) and the high-voltage winding (5);

[0012] Step 3: In the case of step 2, the data obtained is calculated to obtain the current of the low-voltage winding and the high-voltage winding lead wires. The specific calculation method is as follows:

[0013] It is known that the injected signal is a square wave with a frequency of f. The collected induced voltages U1(t) and U2(t) of the high-voltage winding (5) and the low-voltage winding (4) need to be decomposed by Fourier to obtain the fundamental amplitudes. The fundamental amplitudes U1 and U2 are calculated according to the following formula:

[0014]

[0015] Given the resistances R2 and R3 of the signal amplifier circuit, the resistance R1 of the voltage-current conversion circuit, and the calculated voltages U1 and U2, the lead-out currents I1 and I2 on the winding can be obtained using the following formula:

[0016]

[0017] Step 4: Repeat steps 2 and 3, set the power frequency f from 100kHz to 1MHz, and change it at intervals of 10kHz, to obtain the output amplitude change curve of the transformer's high-voltage winding (5) and low-voltage winding (4) lead wire current, realize online perception of the transformer winding current response signal, and complete online monitoring of the transformer winding status. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] in:

[0020] Figure 1 This is a flowchart of the present invention.

[0021] Figure 2 This is a structural diagram of the overall device involved in the present invention.

[0022] Figure 3 This is a circuit diagram of a signal detection amplifying circuit module and a high-frequency excitation module involved in the present invention. DETAILED DESCRIPTION

[0023] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present application. Instead, they are merely examples of systems and methods consistent with the examples detailed in the attached claims, or with some aspects of the present application.

[0024] It should be noted that, in this article, the terms "include", "comprises" or any other variants thereof are intended to cover descriptions such as non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "includes a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element. In addition, components, features, and elements with the same name in different embodiments of the present application may have the same meaning or different meanings, and their specific meanings need to be determined by their explanation in the specific embodiment or further combined with the context of the specific embodiment.

[0025] It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0026] In the subsequent description, the suffixes such as "module", "component" or "unit" used to represent elements are only used to facilitate the description of the present application, and have no specific meanings. Therefore, "module", "component" or "unit" can be used in a mixed manner.

[0027] The transformer winding state online monitoring device and test method with high-frequency excitation and signal perception proposed in the present invention are characterized in that a high-frequency excitation module is used to inject an excitation signal and a high-frequency signal perception module is used to effectively perceive the transformer winding current response signal, so as to explore the change law of the transformer winding response signal when the transformer winding is online. Specifically, the following steps are included:

[0028] A transformer winding state online monitoring device based on high-frequency excitation and signal perception, characterized in that it comprises a high-frequency excitation injection module (1), a high-frequency signal perception module (2) and a signal acquisition module (3), wherein the high-frequency excitation injection module (1) generates a high-frequency square wave signal and injects it into the transformer winding through a low-voltage winding (4) lead wire, the high-frequency signal perception module (2) is sleeved on the low-voltage winding (4) and high-voltage winding (5) lead wires, and amplifies the sensed signal, and the signal acquisition module (3) transmits the processed signal to a computer (6), thereby realizing effective perception of the excitation signal and the response signal;

[0029] The high-frequency excitation injection module (1) includes a bridge rectifier circuit, specifically including four high-frequency diodes D connected in a specific manner, an output end connected in parallel to a filter capacitor C1, and then connected to a full-bridge inverter circuit, specifically including four high-frequency triodes T connected in a specific manner, wherein a control signal of the full-bridge inverter circuit is remotely controlled by a computer (6), thereby realizing remote control of the high-frequency excitation injection module (1);

[0030] The high-frequency signal sensing module (2) includes a high-frequency current transformer (7), specifically including an open-type nickel-zinc ferrite magnetic ring (8) and a housing fixing device (9). The output end of the transformer is connected to a modulation circuit (10) including a current-voltage conversion circuit and a signal amplification circuit. The current-voltage conversion circuit includes an operational amplifier U1, a conversion resistor R1 and an anti-parallel diode D T , the signal amplifying circuit includes an operational amplifier U2 and amplifying resistors R2 and R3;

[0031] The signal acquisition module (3) comprises an AD7606 acquisition chip, which can convert analog signals into high-precision digital signals. Its input end is connected to a signal amplification circuit, and its output end is connected to a computer (6) via a USB transmission line, so as to achieve effective acquisition of excitation signals and response signals.

[0032] A method for online monitoring of transformer winding status based on high-frequency excitation and signal perception, using the above-mentioned device to perform transformer winding high-frequency signal injection and perception testing, is characterized in that it includes the following steps:

[0033] The first step is to put a high-frequency signal sensing module (2) on the lead-out wires of the high-voltage winding (5) and the low-voltage winding (4), connect the output of the high-frequency signal sensing module (2) to the signal acquisition module (3), connect the signal acquisition module (3) to the computer (6) via a data line, and remotely connect the high-frequency excitation injection module (1) to the computer (6);

[0034] Step 2: Using a computer (6) to send instructions to a high-frequency excitation injection module (1), the high-frequency excitation injection module (1) injects a square wave signal with an amplitude of 20V and a frequency of f=100kHz into the transformer low-voltage winding (4), and transmits the sensed high-frequency signal to the computer (6) via the high-frequency signal sensing module (2) and the signal acquisition module (3) on the lead wires between the low-voltage winding (4) and the high-voltage winding (5);

[0035] Step 3: In the case of step 2, the data obtained is calculated to obtain the current of the low-voltage winding and the high-voltage winding lead wires. The specific calculation method is as follows:

[0036] It is known that the injected signal is a square wave with a frequency of f. The collected induced voltages U1(t) and U2(t) of the high-voltage winding (5) and the low-voltage winding (4) need to be decomposed by Fourier to obtain the fundamental amplitudes. The fundamental amplitudes U1 and U2 are calculated according to the following formula:

[0037]

[0038] Given the resistances R2 and R3 of the signal amplifier circuit, the resistance R1 of the voltage-current conversion circuit, and the calculated voltages U1 and U2, the lead-out currents I1 and I2 on the winding can be obtained using the following formula:

[0039]

[0040] Step 4: Repeat steps 2 and 3, set the power frequency f from 100kHz to 1MHz, and change it at intervals of 10kHz, to obtain the output amplitude change curve of the transformer's high-voltage winding (5) and low-voltage winding (4) lead wire current, realize online perception of the transformer winding current response signal, and complete online monitoring of the transformer winding status.

[0041] It should be noted that, in this article, the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, an element defined by the sentence "comprises a ..." does not exclude the existence of other identical elements in the process, method, article or device including the element.

[0042] The above disclosure is only the preferred embodiment of the present application, which certainly cannot be used to limit the scope of rights of the present application. Therefore, equivalent changes made according to the claims of the present application are still within the scope covered by the present application.

Claims

1. A transformer winding state online monitoring device based on high-frequency excitation and signal sensing, characterized in that: The invention comprises a high-frequency excitation injection module (1), a high-frequency signal sensing module (2) and a signal acquisition module (3), wherein the high-frequency excitation injection module (1) generates a high-frequency square wave signal and injects it into the transformer winding through the lead wire of the low-voltage winding (4), the high-frequency signal sensing module (2) is sleeved on the lead wires of the low-voltage winding (4) and the high-voltage winding (5), and amplifies the sensed signal, and the signal acquisition module (3) transmits the processed signal to a computer (6), thereby realizing effective sensing of the excitation signal and the response signal; The high-frequency excitation injection module (1) includes a bridge rectifier circuit, specifically including four high-frequency diodes D connected in a specific manner, an output end connected in parallel to a filter capacitor C1, and then connected to a full-bridge inverter circuit, specifically including four high-frequency triodes T connected in a specific manner, wherein a control signal of the full-bridge inverter circuit is remotely controlled by a computer (6), thereby realizing remote control of the high-frequency excitation injection module (1); The high-frequency signal sensing module (2) includes a high-frequency current transformer (7), specifically including an open-type nickel-zinc ferrite magnetic ring (8) and a housing fixing device (9). The output end of the transformer is connected to a modulation circuit (10) including a current-voltage conversion circuit and a signal amplification circuit. The current-voltage conversion circuit includes an operational amplifier U1, a conversion resistor R1 and an anti-parallel diode D T , the signal amplifying circuit includes an operational amplifier U2 and amplifying resistors R2 and R3; The signal acquisition module (3) comprises an AD7606 acquisition chip, which can convert analog signals into high-precision digital signals. Its input end is connected to a signal amplification circuit, and its output end is connected to a computer (6) via a USB transmission line, so as to achieve effective acquisition of excitation signals and response signals. The above-mentioned device is used to perform transformer winding high-frequency signal injection and perception testing, which is characterized by comprising the following steps: The first step is to put a high-frequency signal sensing module (2) on the lead-out wires of the high-voltage winding (5) and the low-voltage winding (4), connect the output of the high-frequency signal sensing module (2) to the signal acquisition module (3), connect the signal acquisition module (3) to the computer (6) via a data line, and remotely connect the high-frequency excitation injection module (1) to the computer (6); Step 2: Using a computer (6) to send instructions to a high-frequency excitation injection module (1), the high-frequency excitation injection module (1) injects a square wave signal with an amplitude of 20V and a frequency of f=100kHz into the transformer low-voltage winding (4), and transmits the sensed high-frequency signal to the computer (6) via the high-frequency signal sensing module (2) and the signal acquisition module (3) on the lead wires between the low-voltage winding (4) and the high-voltage winding (5); Step 3: In the case of step 2, the data obtained is calculated to obtain the current of the low-voltage winding and the high-voltage winding lead wires. The specific calculation method is as follows: It is known that the injected signal is a square wave with a frequency of f. The collected induced voltages U1(t) and U2(t) of the high-voltage winding (5) and the low-voltage winding (4) need to be decomposed by Fourier to obtain the fundamental amplitudes. The fundamental amplitudes U1 and U2 are calculated according to the following formula: Given the resistances R2 and R3 of the signal amplifier circuit, the resistance R1 of the voltage-current conversion circuit, and the calculated voltages U1 and U2, the lead-out currents I1 and I2 on the winding can be obtained using the following formula: Step 4: Repeat steps 2 and 3, set the power frequency f from 100kHz to 1MHz, and change it at intervals of 10kHz, to obtain the output amplitude change curve of the transformer's high-voltage winding (5) and low-voltage winding (4) lead wire current, realize online perception of the transformer winding current response signal, and complete online monitoring of the transformer winding status.

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