CN113791369B

CN113791369B - Lissajous figure transformer winding deformation online monitoring method based on third harmonic

Info

Publication number: CN113791369B
Application number: CN202111135313.4A
Authority: CN
Inventors: 李成祥; 戴明; 周言
Original assignee: Chongqing University
Current assignee: Chongqing University
Priority date: 2021-09-27
Filing date: 2021-09-27
Publication date: 2023-01-03
Anticipated expiration: 2041-09-27
Also published as: CN113791369A

Abstract

The invention provides a third harmonic-based on-line monitoring method for the deformation of a Lissajous figure transformer winding, which comprises the following steps of: s1, solving a long axis, a short axis, an inclination angle and eccentricity according to the acquired primary side voltage value, secondary side voltage value and primary side current value of the transformer to be detected; s2, solving a long axis, a short axis, an inclination angle and eccentricity according to the acquired primary side voltage value, secondary side voltage value and primary side current value of the transformer to be detected during working; s3, searching the major axis, the minor axis, the inclination angle and the eccentricity in the reference characteristic quantity set in the step S1 according to the primary side voltage curve and the primary side current curve in the step S2; and S4, judging whether the difference values of the long axis, the short axis, the inclination angle and the eccentricity in the step S2 and the difference values of the long axis, the short axis, the inclination angle and the eccentricity in the reference characteristic quantity set in the step S3 are in a preset range. The invention can measure the winding deformation information of the transformer to be measured.

Description

Lissajous figure transformer winding deformation online monitoring method based on third harmonic

Technical Field

The invention relates to the technical field of transformers, in particular to a method for monitoring the deformation of a Lissajous figure transformer winding on line based on third harmonic.

Background

The transformer is a power device for voltage conversion, and whether the running state of the transformer normally concerns the safety and reliability of power supply of a power grid. Wherein the winding deformation is a main factor causing the operation accident of the transformer. The existing method for constructing the Lissajous figure based on the voltage and the current is carried out by using the fundamental wave, but when the deformation of the transformer winding is tiny, the Lissajous figure constructed by using the fundamental wave voltage and the current has the characteristic quantity which is tiny compared with the change of the normal winding, and whether the winding is deformed or not cannot be judged.

Disclosure of Invention

The invention aims to at least solve the technical problems in the prior art, and particularly creatively provides an on-line monitoring method for the winding deformation of a Lissajous figure transformer based on third harmonic.

In order to achieve the above object, the present invention provides a voltage and current collecting board, which includes a PCB, a current collecting input terminal and a current collecting output terminal, which are disposed on the PCB, wherein the current collecting input terminal includes a high-voltage side current collecting input terminal CN2 and a low-voltage side current collecting input terminal CN1, and the current collecting output terminal includes a high-voltage side current collecting output terminal CN3 and a low-voltage side current collecting output terminal CN4;

the PCB is characterized by further comprising a current regulating module and a current sampling module which are arranged on the PCB, wherein the current regulating module comprises a high-voltage side current regulating module and a low-voltage side current regulating module, the high-voltage side current regulating module comprises a first high-voltage side current regulating module, a second high-voltage side current regulating module and a third high-voltage side current regulating module, and the low-voltage side current regulating module comprises a first low-voltage side current regulating module, a second low-voltage side current regulating module and a third low-voltage side current regulating module; the current sampling module comprises a high-voltage side current sampling module and a low-voltage side current sampling module, the high-voltage side current sampling module comprises a first high-voltage side current sampling module, a second high-voltage side current sampling module and a third high-voltage side current sampling module, and the low-voltage side current sampling module comprises a first low-voltage side current sampling module, a second low-voltage side current sampling module and a third low-voltage side current sampling module;

the input end of the high-voltage side current first regulating module, the input end of the high-voltage side current second regulating module and the input end of the high-voltage side current third regulating module are respectively connected with the output end of a high-voltage side current acquisition input terminal CN2, the output end of the high-voltage side current first regulating module is connected with the input end of a high-voltage side current first sampling module, the output end of the high-voltage side current second regulating module is connected with the input end of a high-voltage side current second sampling module, the output end of the high-voltage side current third regulating module is connected with the input end of a high-voltage side current third sampling module, and the output end of the high-voltage side current first sampling module, the output end of the high-voltage side current second sampling module and the output end of the high-voltage side current third sampling module are respectively connected with the input end of a high-voltage side current acquisition output terminal CN 3;

the input end of the low-voltage side current first regulating module, the input end of the low-voltage side current second regulating module and the input end of the low-voltage side current third regulating module are respectively connected with the output end of a low-voltage side current acquisition input terminal CN1, the output end of the low-voltage side current first regulating module is connected with the input end of a low-voltage side current first sampling module, the output end of the low-voltage side current second regulating module is connected with the input end of a low-voltage side current second sampling module, the output end of the low-voltage side current third regulating module is connected with the input end of a low-voltage side current third sampling module, and the output end of the low-voltage side current first sampling module, the output end of the low-voltage side current second sampling module and the output end of the low-voltage side current third sampling module are respectively connected with the input end of a low-voltage side current acquisition output terminal CN4;

the voltage acquisition output terminal comprises a high-voltage side voltage acquisition output terminal CN6 and a low-voltage side voltage acquisition output terminal CN5;

the PCB voltage regulation device is characterized by further comprising a voltage regulation module arranged on the PCB, wherein the voltage regulation module comprises a high-voltage side voltage regulation module and a low-voltage side voltage regulation module, the high-voltage side voltage regulation module comprises a first high-voltage side voltage regulation module, a second high-voltage side voltage regulation module and a third high-voltage side voltage regulation module, and the low-voltage side voltage regulation module comprises a first low-voltage side voltage regulation module, a second low-voltage side voltage regulation module and a third low-voltage side voltage regulation module;

the input end of the first high-side voltage regulating module, the input end of the second high-side voltage regulating module, the input end of the third high-side voltage regulating module, the input end of the first low-side voltage regulating module, the input end of the second low-side voltage regulating module and the input end of the third low-side voltage regulating module are respectively connected with the output end of the voltage acquisition input terminal U1, the output end of the first high-side voltage regulating module, the output end of the second high-side voltage regulating module and the output end of the third high-side voltage regulating module are respectively connected with the input end of the high-side voltage acquisition output terminal CN6, and the output end of the first low-side voltage regulating module, the output end of the second low-side voltage regulating module and the output end of the third low-side voltage regulating module are respectively connected with the input end of the low-side voltage acquisition output terminal CN 5.

In a preferred embodiment of the present invention, the first high-side current adjusting module includes a current transformer L6, a first input end of the current transformer L6 is connected to a fifth output end of the high-side current collecting input terminal CN2, a second input end of the current transformer L6 is connected to a sixth output end of the high-side current collecting input terminal CN2, and a first output end of the current transformer L6 and a second output end of the current transformer L6 are respectively connected to an input end of the first high-side current sampling module;

or/and the high-voltage side current second regulating module comprises a current transformer L5, the input first end of the current transformer L5 is connected with the output third end of the high-voltage side current acquisition input terminal CN2, the input second end of the current transformer L5 is connected with the output fourth end of the high-voltage side current acquisition input terminal CN2, and the output first end of the current transformer L5 and the output second end of the current transformer L5 are respectively connected with the input end of the high-voltage side current second sampling module;

or/and the third high-voltage side current regulating module comprises a current transformer L4, a first input end of the current transformer L4 is connected with a first output end of the high-voltage side current collecting input terminal CN2, a second input end of the current transformer L4 is connected with a second output end of the high-voltage side current collecting input terminal CN2, and a first output end of the current transformer L4 and a second output end of the current transformer L4 are respectively connected with an input end of the third high-voltage side current sampling module;

or/and the first low-voltage side current regulating module comprises a current transformer L3, the first input end of the current transformer L3 is connected with the fifth output end of the low-voltage side current acquisition input terminal CN1, the second input end of the current transformer L3 is connected with the sixth output end of the low-voltage side current acquisition input terminal CN1, and the first output end of the current transformer L3 and the second output end of the current transformer L3 are respectively connected with the input end of the first low-voltage side current sampling module;

or/and the low-voltage side current second regulating module comprises a current transformer L2, the input first end of the current transformer L2 is connected with the output third end of the low-voltage side current acquisition input terminal CN1, the input second end of the current transformer L2 is connected with the output fourth end of the low-voltage side current acquisition input terminal CN1, and the output first end of the current transformer L2 and the output second end of the current transformer L2 are respectively connected with the input end of the low-voltage side current second sampling module;

or/and the third low-voltage side current regulating module comprises a current transformer L1, the first input end of the current transformer L1 is connected with the first output end of the low-voltage side current acquisition input terminal CN1, the second input end of the current transformer L1 is connected with the second output end of the low-voltage side current acquisition input terminal CN1, and the first output end of the current transformer L1 and the second output end of the current transformer L1 are connected with the input end of the third low-voltage side current sampling module respectively.

In a preferred embodiment of the present invention, the high-side current first sampling module includes an amplifier U5, a positive phase input terminal of the amplifier U5 and an inverse phase input terminal of the amplifier U5 are respectively connected to an output terminal of the high-side current first adjusting module, the inverse phase input terminal of the amplifier U5 is further connected to a first end of a resistor R5 and an input second end of the high-side current collection output terminal CN3, the positive phase input terminal of the amplifier U5 is further connected to a power ground, an output terminal of the amplifier U5 is respectively connected to a second end of the resistor R5 and an input first end of the high-side current collection output terminal CN3, a power positive terminal of the amplifier U5 is connected to a power supply V1+, and a power negative terminal of the amplifier U5 is connected to a power supply V1-;

or/and the high-voltage side current second sampling module comprises an amplifier U4, a positive phase input end of the amplifier U4 and an inverse phase input end of the amplifier U4 are respectively connected with an output end of the high-voltage side current second regulating module, the inverse phase input end of the amplifier U4 is also connected with a first end of a resistor R4 and an input fourth end of a high-voltage side current collection output terminal CN3, the positive phase input end of the amplifier U4 is also connected with a power ground, an output end of the amplifier U4 is respectively connected with a second end of the resistor R4 and an input third end of the high-voltage side current collection output terminal CN3, a power positive end of the amplifier U4 is connected with a power supply V1+, and a power negative end of the amplifier U4 is connected with the power supply V1-;

or/and the third high-voltage side current sampling module comprises an amplifier U3, a positive phase input end of the amplifier U3 and an inverted phase input end of the amplifier U3 are respectively connected with an output end of the third high-voltage side current regulating module, the inverted phase input end of the amplifier U3 is also connected with a first end of a resistor R3 and an input sixth end of a high-voltage side current collecting output terminal CN3, the positive phase input end of the amplifier U3 is also connected with a power ground, an output end of the amplifier U3 is respectively connected with a second end of the resistor R3 and an input fifth end of the high-voltage side current collecting output terminal CN3, a power positive end of the amplifier U3 is connected with a power supply V1+, and a power negative end of the amplifier U3 is connected with the power supply V1-;

or/and the first low-voltage side current sampling module comprises an amplifier U7, a positive phase input end of the amplifier U7 and an inverted phase input end of the amplifier U7 are respectively connected with an output end of the first low-voltage side current regulating module, an inverted phase input end of the amplifier U7 is also connected with a first end of a resistor R6 and an input second end of a low-voltage side current collection output terminal CN4, a positive phase input end of the amplifier U7 is also connected with a power ground, an output end of the amplifier U7 is respectively connected with a second end of the resistor R6 and an input first end of the low-voltage side current collection output terminal CN4, a power positive end of the amplifier U7 is connected with a power supply V1+, and a power negative end of the amplifier U7 is connected with the power supply V1-;

or/and the low-voltage side current second sampling module comprises an amplifier U8, a positive phase input end of the amplifier U8 and an inverted phase input end of the amplifier U8 are respectively connected with an output end of the low-voltage side current second regulating module, an inverted phase input end of the amplifier U8 is also connected with a first end of a resistor R7 and an input fourth end of a low-voltage side current collection output terminal CN4, a positive phase input end of the amplifier U8 is also connected with a power ground, an output end of the amplifier U8 is respectively connected with a second end of the resistor R7 and an input third end of the low-voltage side current collection output terminal CN4, a power positive end of the amplifier U8 is connected with a power supply V1+, and a power negative end of the amplifier U8 is connected with the power supply V1-;

or/and the third low-voltage side current sampling module comprises an amplifier U9, a positive phase input end of the amplifier U9 and an inverted phase input end of the amplifier U9 are respectively connected with an output end of the third low-voltage side current regulating module, the inverted phase input end of the amplifier U9 is further connected with a first end of a resistor R8 and an input sixth end of a low-voltage side current collection output terminal CN4, the positive phase input end of the amplifier U9 is further connected with a power ground, an output end of the amplifier U9 is respectively connected with a second end of the resistor R8 and an input fifth end of the low-voltage side current collection output terminal CN4, a power positive end of the amplifier U9 is connected with a power supply V1+, and a power negative end of the amplifier U9 is connected with the power supply V1-.

In a preferred embodiment of the present invention, the protection module further comprises a high-voltage side protection module and a low-voltage side protection module, wherein the high-voltage side protection module comprises a first high-voltage side protection module, a second high-voltage side protection module and a third high-voltage side protection module, and the low-voltage side protection module comprises a first low-voltage side protection module, a second low-voltage side protection module and a third low-voltage side protection module;

the high-voltage side first protection module is connected in parallel with the output end of the high-voltage side current first regulation module or the input end of the high-voltage side current first sampling module, the high-voltage side second protection module is connected in parallel with the output end of the high-voltage side current second regulation module or the input end of the high-voltage side current second sampling module, and the high-voltage side third protection module is connected in parallel with the output end of the high-voltage side current third regulation module or the input end of the high-voltage side current third sampling module;

the low-voltage side first protection module is connected in parallel at the output end of the low-voltage side current first regulation module or the input end of the low-voltage side current first sampling module, the low-voltage side second protection module is connected in parallel at the output end of the low-voltage side current second regulation module or the input end of the low-voltage side current second sampling module, and the low-voltage side third protection module is connected in parallel at the output end of the low-voltage side current third regulation module or the input end of the low-voltage side current third sampling module.

In a preferred embodiment of the present invention, the high-voltage side first protection module includes a diode D3 and a diode D4, an anode of the diode D3 is connected to a cathode of the diode D4, and a cathode of the diode D3 is connected to an anode of the diode D4;

the high-voltage side second protection module comprises a diode D1 and a diode D2, the anode of the diode D1 is connected with the cathode of the diode D2, and the cathode of the diode D1 is connected with the anode of the diode D2;

the high-voltage side third protection module comprises a diode D6 and a diode D5, wherein the anode of the diode D6 is connected with the cathode of the diode D5, and the cathode of the diode D6 is connected with the anode of the diode D5;

the low-voltage side first protection module comprises a diode D7 and a diode D8, wherein the anode of the diode D7 is connected with the cathode of the diode D8, and the cathode of the diode D7 is connected with the anode of the diode D8;

the low-voltage side second protection module comprises a diode D9 and a diode D10, wherein the anode of the diode D9 is connected with the cathode of the diode D10, and the cathode of the diode D9 is connected with the anode of the diode D10;

the low-voltage side third protection module comprises a diode D11 and a diode D12, wherein the anode of the diode D11 is connected with the cathode of the diode D12, and the cathode of the diode D11 is connected with the anode of the diode D12.

In a preferred embodiment of the present invention, the high-side voltage first regulation module includes a voltage transformer U15, an input first end of the voltage transformer U15 is connected to the output ninth end of the voltage acquisition input terminal U1 and the power ground, respectively, an input second end of the voltage transformer U15 is connected to the output sixth end of the voltage acquisition input terminal U1, an output first end of the voltage transformer U15 is connected to the input second end of the high-side voltage acquisition output terminal CN6, the protection end of the voltage transformer U15 and the power ground, respectively, and an output second end of the voltage transformer U15 is connected to the input first end of the high-side voltage acquisition output terminal CN 6;

or/and the second high-voltage side voltage regulating module comprises a voltage transformer U14, the first input end of the voltage transformer U14 is respectively connected with the eighth output end of the voltage acquisition input terminal U1 and the power ground, the second input end of the voltage transformer U14 is connected with the fifth output end of the voltage acquisition input terminal U1, the first output end of the voltage transformer U14 is respectively connected with the fourth input end of the high-voltage side voltage acquisition output terminal CN6, the protection end of the voltage transformer U14 and the power ground, and the second output end of the voltage transformer U14 is connected with the third input end of the high-voltage side voltage acquisition output terminal CN 6;

or/and the third high-voltage side voltage regulating module comprises a voltage transformer U13, the input first end of the voltage transformer U13 is respectively connected with the output seventh end of the voltage acquisition input terminal U1 and the power ground, the input second end of the voltage transformer U13 is connected with the output fourth end of the voltage acquisition input terminal U1, the output first end of the voltage transformer U13 is respectively connected with the input sixth end of the high-voltage side voltage acquisition output terminal CN6, the protection end of the voltage transformer U13 and the power ground, and the output second end of the voltage transformer U13 is connected with the input fifth end of the high-voltage side voltage acquisition output terminal CN 6;

or/and the first low-voltage side voltage regulating module comprises a voltage transformer U12, the first input end of the voltage transformer U12 is respectively connected with the protection end of the voltage transformer U12 and the power ground, the second input end of the voltage transformer U12 is connected with the third output end of the voltage acquisition input terminal U1, the first output end of the voltage transformer U12 is respectively connected with the first input end of the low-voltage side voltage acquisition output terminal CN5 and the power ground, and the second output end of the voltage transformer U12 is connected with the second input end of the low-voltage side voltage acquisition output terminal CN5;

or/and the second low-voltage side voltage regulating module comprises a voltage transformer U10, the first input end of the voltage transformer U10 is respectively connected with the protection end of the voltage transformer U10 and the power ground, the second input end of the voltage transformer U10 is connected with the second output end of the voltage acquisition input terminal U1, the first output end of the voltage transformer U10 is respectively connected with the third input end of the low-voltage side voltage acquisition output terminal CN5 and the power ground, and the second output end of the voltage transformer U10 is connected with the fourth input end of the low-voltage side voltage acquisition output terminal CN5;

or/and the third low-voltage side voltage regulating module comprises a voltage transformer U11, the first input end of the voltage transformer U11 is connected with the protection end of the voltage transformer U11 and the power ground respectively, the second input end of the voltage transformer U11 is connected with the first output end of the voltage acquisition input terminal U1, the first output end of the voltage transformer U11 is connected with the fifth input end of the low-voltage side voltage acquisition output terminal CN5 and the power ground respectively, and the second output end of the voltage transformer U11 is connected with the sixth input end of the low-voltage side voltage acquisition output terminal CN 5.

In a preferred embodiment of the present invention, the power supply module further comprises a power supply module disposed on the PCB, the power supply module comprises an AC/DC chip unit U2, a live line end L of the AC/DC chip unit U2 is connected to a first end of the voltage dependent resistor R2 and a first end of the thermistor R1, a second end of the thermistor R1 is connected to a first input end of the power interface U6, a live line end N of the AC/DC chip unit U2 is connected to a second end of the voltage dependent resistor R2 and a second input end of the power interface U6, and a power ground end EGND of the AC/DC chip unit U2 is connected to a power ground; the positive power output terminal + V0 of the AC/DC chip unit U2 is connected with the first end of the capacitor C2, the positive power output terminal + V0 of the AC/DC chip unit U2 outputs the power supply V1+, the negative power output terminal-V0 of the AC/DC chip unit U2 is connected with the first end of the capacitor C1, the negative power output terminal-V0 of the AC/DC chip unit U2 outputs the power supply V1-, and the common end of the AC/DC chip unit U2 is respectively connected with the second end of the capacitor C1, the second end of the capacitor C2 and the power ground.

The invention also discloses a data acquisition card, which comprises a PCB (printed Circuit Board), an A/D (analog to digital) conversion module, a controller and a wireless data transceiver module, wherein the A/D conversion module, the controller and the wireless data transceiver module are arranged on the PCB;

the data input end of the A/D conversion module is connected with the data output end of the socket, the data output end of the A/D conversion module is connected with the A/D data input end of the controller, and the wireless data transceiving end of the controller is connected with the data transceiving end of the wireless data transceiving module;

after the acquired analog signals are converted into digital signals, the digital signals are transmitted to a computing terminal through a wireless data transceiver module, and the running state of the transformer to be tested is computed.

In a preferred embodiment of the present invention, the a/D conversion module includes an a/D conversion current unit and an a/D conversion voltage unit, the a/D conversion current unit includes an a/D conversion high-side current unit and an a/D conversion low-side current unit, the a/D conversion high-side current unit includes an a/D conversion high-side current first unit, an a/D conversion high-side current second unit, and an a/D conversion high-side current third unit, and the a/D conversion low-side current unit includes an a/D conversion low-side current first unit, an a/D conversion low-side current second unit, and an a/D conversion low-side current third unit;

the A/D conversion voltage unit comprises an A/D conversion high-voltage side voltage unit and an A/D conversion low-voltage side voltage unit, the A/D conversion high-voltage side voltage unit comprises an A/D conversion high-voltage side voltage first unit, an A/D conversion high-voltage side voltage second unit and an A/D conversion high-voltage side voltage third unit, and the A/D conversion low-voltage side voltage unit comprises an A/D conversion low-voltage side voltage first unit, an A/D conversion low-voltage side voltage second unit and an A/D conversion low-voltage side voltage third unit;

the current data input end of a first unit of the A/D conversion high-voltage side current is connected with a first plug socket, the current data output end of the first unit of the A/D conversion high-voltage side current is connected with a first input end of the A/D current data of the controller, the current data input end of a second unit of the A/D conversion high-voltage side current is connected with a second plug socket, the current data output end of the second unit of the A/D conversion high-voltage side current is connected with a second input end of the A/D current data of the controller, the current data input end of a third unit of the A/D conversion high-voltage side current is connected with a third plug socket, and the current data output end of a third unit of the A/D conversion high-voltage side current is connected with a third input end of the A/D current data of the controller;

the current data input end of the first A/D conversion low-voltage side current unit is connected with the fourth plug socket, the current data output end of the first A/D conversion low-voltage side current unit is connected with the first A/D current data input end of the controller, the current data input end of the second A/D conversion low-voltage side current unit is connected with the fifth plug socket, the current data output end of the second A/D conversion low-voltage side current unit is connected with the second A/D current data input end of the controller, the current data input end of the third A/D conversion low-voltage side current unit is connected with the sixth plug socket, and the current data output end of the third A/D conversion low-voltage side current unit is connected with the third A/D current data input end of the controller;

the voltage data input end of a first unit of the A/D conversion high-voltage side voltage is connected with a seventh socket, the voltage data output end of the first unit of the A/D conversion high-voltage side voltage is connected with a first input end of the A/D voltage data of the controller, the voltage data input end of a second unit of the A/D conversion high-voltage side voltage is connected with an eighth socket, the voltage data output end of the second unit of the A/D conversion high-voltage side voltage is connected with a second input end of the A/D voltage data of the controller, the voltage data input end of a third unit of the A/D conversion high-voltage side voltage is connected with a ninth socket, and the voltage data output end of a third unit of the A/D conversion high-voltage side voltage is connected with a third input end of the A/D voltage data of the controller;

the voltage data input end of the first unit of the voltage at the low-voltage side of the A/D conversion is connected with the tenth plug socket, the voltage data output end of the first unit of the voltage at the low-voltage side of the A/D conversion is connected with the first input end of the voltage data at the A/D conversion, the voltage data input end of the second unit of the voltage at the low-voltage side of the A/D conversion is connected with the eleventh plug socket, the voltage data output end of the second unit of the voltage at the low-voltage side of the A/D conversion is connected with the second input end of the voltage data at the A/D conversion, the voltage data input end of the third unit of the voltage at the low-voltage side of the A/D conversion is connected with the twelfth plug socket, and the voltage data output end of the third unit of the voltage at the low-voltage side of the A/D conversion is connected with the third input end of the voltage data at the A/D conversion.

The invention provides a third harmonic-based on-line monitoring method for the deformation of a Lissajous figure transformer winding, which comprises the following steps of:

s1, acquiring a primary side voltage value, a secondary side voltage value and a primary side current value of a transformer to be tested when the transformer leaves a factory; solving one or any combination characteristic quantity of a long axis, a short axis, an inclination angle and eccentricity according to the acquired primary side voltage value, secondary side voltage value and primary side current value of the transformer to be detected; forming a reference characteristic quantity set by one or any combination of the solved long axis, short axis, inclination angle and eccentricity and the corresponding delivery primary side voltage difference curve and delivery primary side current curve;

s2, acquiring a primary side voltage value, a secondary side voltage value and a primary side current value of the transformer to be detected during working; solving one or any combination characteristic quantity of a long axis, a short axis, an inclination angle and eccentricity according to the acquired primary side voltage value, secondary side voltage value and primary side current value of the transformer to be detected during working;

s3, searching one or any combination characteristic quantity of the long axis, the short axis, the inclination angle and the eccentricity in the reference characteristic quantity set in the step S1 according to the primary side voltage curve and the primary side current curve in the step S2;

s4, judging whether the difference value between one or any combination of the characteristic quantity of the long axis, the short axis, the inclination angle and the eccentricity in the step S2 and one or any combination of the characteristic quantity of the long axis, the short axis, the inclination angle and the eccentricity in the reference characteristic quantity set in the step S3 is within a preset range:

if the difference value between one or any combination characteristic quantity of the long axis, the short axis, the inclination angle and the eccentricity in the step S2 and one or any combination characteristic quantity of the long axis, the short axis, the inclination angle and the eccentricity in the reference characteristic quantity set in the step S3 is within a preset range, the transformer winding to be tested is normal;

and if the difference value between one or any combination characteristic quantity of the long axis, the short axis, the inclination angle and the eccentricity in the step S2 and one or any combination characteristic quantity of the long axis, the short axis, the inclination angle and the eccentricity in the reference characteristic quantity set in the step S3 is not within a preset range, the transformer winding to be tested is abnormal, and early warning and transformer position information are sent.

In a preferred embodiment of the present invention, in step S1, the method for solving one or any combination of feature quantities of a long axis, a short axis, an inclination angle and an eccentricity according to the acquired primary side voltage value, secondary side voltage value and primary side current value of the transformer to be measured includes the following steps:

s11, converting a secondary side voltage value of the transformer to be tested when the transformer leaves a factory into a primary side conversion voltage value of the transformer, and calculating a primary side difference value of the transformer according to the obtained primary side conversion voltage value of the transformer; the method for calculating the difference value of the original delivery side comprises the following steps:

wherein, U ₁ The secondary side voltage value of the transformer to be tested when leaving the factory is represented;

U ₂ representing the original conversion voltage value of the factory;

representing the turn ratio of the transformer to be tested; i.e. K ₁ Representing the number of turns of the secondary side of the transformer to be tested; k ₂ Representing the number of turns of the primary side of the transformer to be tested;

wherein U _3_1 represents the difference value of the primary side of the factory;

U ₂ the conversion voltage value of the original side of the factory is represented;

u represents the voltage value of the primary side of the transformer to be tested when the transformer leaves the factory;

s12, respectively fitting a factory primary side difference curve and a factory primary side current curve according to the primary side difference and the primary side current value of the transformer to be tested when the transformer is factory;

and S13, drawing a Lissajous figure by using the difference curve of the factory primary side and the current curve of the factory primary side which are obtained by fitting, and calculating by using curve parameters to obtain one or any combination characteristic quantity of the major axis, the minor axis, the inclination angle and the eccentricity of the ellipse.

In a preferred embodiment of the present invention, in step S2, the method for solving one or any combination of characteristic quantities of a major axis, a minor axis, an inclination angle, and an eccentricity according to the primary side voltage value, the secondary side voltage value, and the primary side current value of the transformer to be measured during operation includes the following steps:

s21, converting a secondary side voltage value of the transformer to be tested during working into a working primary side conversion voltage value, and calculating according to the working primary side conversion voltage value to obtain a working primary side difference value; the method for calculating the difference value of the working primary side comprises the following steps:

wherein, U ₁ "represents the secondary side voltage value of the transformer to be measured during operation;

U ₂ "represents the value of the primary side switching voltage;

representing the turn ratio of the transformer to be tested;

is represented by

The reciprocal of (a);

wherein U _3_1' represents the primary side difference value of the transformer to be measured during working;

U ₂ "represents the value of the primary side switching voltage;

u' represents the voltage value of the primary side of the transformer to be measured;

s22, respectively fitting a working primary side difference curve and a working primary side current curve according to the primary side difference and the primary side current value of the transformer to be measured during working;

and S23, calculating one or any combination characteristic quantity of the major axis, the minor axis, the inclination angle and the eccentricity of the ellipse by using the working primary side difference curve and the working primary side current curve obtained by fitting.

The invention also provides a Lissajous figure transformer winding deformation online monitoring method based on third harmonic, which comprises the following steps:

s1, acquiring a primary side voltage value, a secondary side voltage value and a secondary side current value of a transformer to be tested when the transformer leaves a factory; solving one or any combination characteristic quantity of a long axis, a short axis, an inclination angle and eccentricity according to the acquired primary side voltage value, secondary side voltage value and secondary side current value of the transformer to be detected; forming a reference characteristic quantity set by using the solved one or any combination characteristic quantity of the long axis, the short axis, the inclination angle and the eccentricity as well as a corresponding factory secondary side voltage difference curve and a factory secondary side current curve;

s2, acquiring a primary side voltage value, a secondary side voltage value and a secondary side current value of the transformer to be detected during working; solving one or any combination characteristic quantity of a long axis, a short axis, an inclination angle and eccentricity according to the acquired primary side voltage value, secondary side voltage value and secondary side current value of the transformer to be detected during working;

s3, searching one or any combination characteristic quantity of the major axis, the minor axis, the inclination angle and the eccentricity in the reference characteristic quantity set in the step S1 according to the secondary side voltage curve and the secondary side current curve in the step S2;

and if the difference value between one or any combination characteristic quantity of the long axis, the short axis, the inclination angle and the eccentricity in the step S2 and one or any combination characteristic quantity of the long axis, the short axis, the inclination angle and the eccentricity in the reference characteristic quantity set in the step S3 is not within the preset range, the winding of the transformer to be tested is abnormal, and the position of the transformer to be tested is sent to a maintenance worker.

In a preferred embodiment of the present invention, in step S1, the method for solving one or any combination of feature quantities of a major axis, a minor axis, an inclination angle and an eccentricity according to the acquired primary side voltage value, the secondary side voltage value and the secondary side current value of the transformer to be tested includes the following steps:

s15, converting the primary side voltage value of the transformer to be tested when the transformer leaves the factory into a factory secondary side conversion voltage value, and calculating a factory secondary side difference value according to the obtained factory secondary side conversion voltage value; the method for calculating the difference value of the leaving auxiliary side comprises the following steps:

wherein, U represents the primary side voltage value of the transformer to be tested when leaving the factory;

U ₂ ' represents a factory secondary side conversion voltage value;

to represent

The reciprocal of (a);

wherein, the delta U' represents the difference value of the factory auxiliary side;

U ₂ ' represents a factory secondary side conversion voltage value;

U ₁ indicating transformer to be testedThe secondary side voltage value when leaving the factory;

s12, respectively fitting a factory secondary side difference value curve and a factory secondary side current curve according to a secondary side difference value and a secondary side current value of the transformer to be tested when the transformer leaves a factory;

and S13, calculating to obtain one or any combination characteristic quantity of the major axis, the minor axis, the inclination angle and the eccentricity of the ellipse by using the fitted delivery minor side difference value curve and the delivery minor side current curve.

In a preferred embodiment of the present invention, in step S2, the method for solving one or any combination of characteristic quantities of a major axis, a minor axis, an inclination angle, and an eccentricity according to the primary side voltage value, the secondary side voltage value, and the secondary side current value of the transformer to be tested during operation includes the following steps:

s21, converting a primary side voltage value of the transformer to be tested during working into a working secondary side conversion voltage value, and calculating according to the working secondary side conversion voltage value to obtain a working secondary side difference value; the method for calculating the difference value of the working secondary side comprises the following steps:

wherein, U ₁ "represents a value of the secondary side switching voltage;

U ₂ "represents the voltage value of the primary side of the transformer to be measured when in operation;

representing the turn ratio of the transformer to be tested;

is represented by

The reciprocal of (a);

wherein U _3_1' represents the secondary side difference value of the transformer to be tested when the transformer to be tested works;

U ₁ "represents a value of the secondary side switching voltage;

u' represents the voltage value of the secondary side of the transformer to be tested;

s22, respectively fitting a working secondary side difference value curve and a working secondary side current curve according to the secondary side difference value and the secondary side current value of the transformer to be detected during working;

and S23, calculating one or any combination characteristic quantity of the major axis, the minor axis, the inclination angle and the eccentricity of the ellipse by using the working minor side difference curve and the working minor side current curve obtained by fitting.

In conclusion, due to the adoption of the technical scheme, the transformer winding deformation information can be measured and safely transmitted for the transformer to be measured.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 is a schematic diagram of the voltage acquisition circuit of the present invention.

FIG. 2 is a schematic diagram of the current acquisition circuit connection of the present invention.

Fig. 3 is a circuit connection diagram of the power supply module of the present invention.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the accompanying drawings are illustrative only for the purpose of explaining the present invention, and are not to be construed as limiting the present invention.

The invention provides a voltage and current collecting plate which comprises a PCB (printed circuit board), and a current collecting input terminal and a current collecting output terminal which are arranged on the PCB, wherein the current collecting input terminal comprises a high-voltage side current collecting input terminal CN2 and a low-voltage side current collecting input terminal CN1, and the current collecting output terminal comprises a high-voltage side current collecting output terminal CN3 and a low-voltage side current collecting output terminal CN4;

the PCB is characterized by further comprising a current regulating module and a current sampling module which are arranged on the PCB, wherein the current regulating module comprises a high-voltage side current regulating module and a low-voltage side current regulating module, the high-voltage side current regulating module comprises a first high-voltage side current regulating module, a second high-voltage side current regulating module and a third high-voltage side current regulating module, and the low-voltage side current regulating module comprises a first low-voltage side current regulating module, a second low-voltage side current regulating module and a third low-voltage side current regulating module; the current sampling module comprises a high-voltage side current sampling module and a low-voltage side current sampling module, the high-voltage side current sampling module comprises a high-voltage side current first sampling module, a high-voltage side current second sampling module and a high-voltage side current third sampling module, and the low-voltage side current sampling module comprises a low-voltage side current first sampling module, a low-voltage side current second sampling module and a low-voltage side current third sampling module;

the PCB voltage regulation device comprises a PCB and a PCB, and is characterized by further comprising a voltage regulation module arranged on the PCB, wherein the voltage regulation module comprises a high-voltage side voltage regulation module and a low-voltage side voltage regulation module, the high-voltage side voltage regulation module comprises a high-voltage side voltage first regulation module, a high-voltage side voltage second regulation module and a high-voltage side voltage third regulation module, and the low-voltage side voltage regulation module comprises a low-voltage side voltage first regulation module, a low-voltage side voltage second regulation module and a low-voltage side voltage third regulation module;

or/and the high-voltage side current second adjusting module comprises a current transformer L5, the input first end of the current transformer L5 is connected with the output third end of the high-voltage side current acquisition input terminal CN2, the input second end of the current transformer L5 is connected with the output fourth end of the high-voltage side current acquisition input terminal CN2, and the output first end of the current transformer L5 and the output second end of the current transformer L5 are respectively connected with the input end of the high-voltage side current second sampling module;

or/and the third high-voltage side current regulating module comprises a current transformer L4, the first input end of the current transformer L4 is connected with the first output end of the high-voltage side current acquisition input terminal CN2, the second input end of the current transformer L4 is connected with the second output end of the high-voltage side current acquisition input terminal CN2, and the first output end of the current transformer L4 and the second output end of the current transformer L4 are respectively connected with the input end of the third high-voltage side current sampling module;

or/and the low-voltage side current third adjusting module comprises a current transformer L1, the input first end of the current transformer L1 is connected with the output first end of the low-voltage side current acquisition input terminal CN1, the input second end of the current transformer L1 is connected with the output second end of the low-voltage side current acquisition input terminal CN1, and the output first end of the current transformer L1 and the output second end of the current transformer L1 are respectively connected with the input end of the low-voltage side current third sampling module.

or/and the second high-voltage side current sampling module comprises an amplifier U4, a positive phase input end of the amplifier U4 and an inverted phase input end of the amplifier U4 are respectively connected with an output end of the second high-voltage side current regulating module, the inverted phase input end of the amplifier U4 is further connected with a first end of a resistor R4 and an input fourth end of a high-voltage side current collecting output terminal CN3, the positive phase input end of the amplifier U4 is further connected with a power ground, an output end of the amplifier U4 is respectively connected with a second end of the resistor R4 and an input third end of the high-voltage side current collecting output terminal CN3, a power supply positive end of the amplifier U4 is connected with a power supply V1+, and a power supply negative end of the amplifier U4 is connected with the power supply V1-;

or/and the third high-voltage side current sampling module comprises an amplifier U3, a positive phase input end of the amplifier U3 and an inverted phase input end of the amplifier U3 are respectively connected with an output end of the third high-voltage side current regulating module, the inverted phase input end of the amplifier U3 is further connected with a first end of a resistor R3 and an input sixth end of a high-voltage side current collecting output terminal CN3, the positive phase input end of the amplifier U3 is further connected with a power ground, an output end of the amplifier U3 is respectively connected with a second end of the resistor R3 and an input fifth end of the high-voltage side current collecting output terminal CN3, a power supply positive end of the amplifier U3 is connected with a power supply V1+, and a power supply negative end of the amplifier U3 is connected with the power supply V1-;

or/and the third low-voltage side current sampling module comprises an amplifier U9, a positive phase input end of the amplifier U9 and an inverted phase input end of the amplifier U9 are respectively connected with an output end of the third low-voltage side current regulating module, the inverted phase input end of the amplifier U9 is further connected with a first end of a resistor R8 and an input sixth end of a low-voltage side current collection output terminal CN4, the positive phase input end of the amplifier U9 is further connected with a power ground, an output end of the amplifier U9 is respectively connected with a second end of the resistor R8 and an input fifth end of the low-voltage side current collection output terminal CN4, a power positive end of the amplifier U9 is connected with a power supply V1+, and a power negative end of the amplifier U9 is connected with the power supply V1-. An amplifier is connected to the output end of the current transformer, op07 is adopted by the amplifier (amplifiers U3-U5 and U7-U9), voltage drop on the secondary side of the current transformer is zero according to the virtual short characteristic of operational amplifier, the current transformer works in a short circuit state, power on sampling resistors (resistors R3-R8) actually comes from a power supply module, and the accuracy of the current transformer is guaranteed not to be influenced due to the operation with a load. The types of the high-voltage side current collection input terminal CN2, the low-voltage side current collection input terminal CN1, the high-voltage side current collection output terminal CN3 and the low-voltage side current collection output terminal CN4 can be DB128V-5.0-6P, the types of the diodes D1-12 can be 1N4007, and the types of the resistors R3-8 can be R-EU _ VTA56.

the low-voltage side third protection module comprises a diode D11 and a diode D12, wherein the anode of the diode D11 is connected with the cathode of the diode D12, and the cathode of the diode D11 is connected with the anode of the diode D12. Two rectifier diodes which are reversely connected in parallel at the secondary side of the current transformer play a role in protection. Firstly, the group of diodes can ensure that the voltage of the input end of the operational amplifier op07 is approximately zero; secondly, when the detection system stops operating, the external power supply is disconnected, the operational amplifier op07 cannot normally work, and at the moment, the two diodes are conducted in stages, so that the micro current transformer can be ensured to work in a short-circuit state all the time. When the detection system starts to operate, the op07 starts to be electrified and works, due to the virtual short characteristic of the operational amplifier, the voltage of the input port is zero, the forward conducting voltage of the diode is 0.7V, and therefore the diode cannot be conducted and enters the turn-off state. At this time, the secondary side current of the current transformer directly flows to the op-amp op07. And because the operational amplifier has a virtual-break characteristic when working normally, the current of the input port is zero, the secondary side current of the current transformer flows into the sampling resistor between the inverted input end and the output end, and the voltage at two ends of the sampling resistor is taken as an output signal to be sent to the data acquisition card, so that the function of converting a large-current signal into a small-voltage signal is finally realized.

As shown in fig. 1, the voltage acquisition circuit is specifically connected, where a first input end of a current transformer L6 is connected to a fifth output end of the high-voltage side current acquisition input terminal CN2, a second input end of the current transformer L6 is connected to a sixth output end of the high-voltage side current acquisition input terminal CN2, a first input end of a current transformer L5 is connected to a third output end of the high-voltage side current acquisition input terminal CN2, a second input end of the current transformer L5 is connected to a fourth output end of the high-voltage side current acquisition input terminal CN2, a first input end of a current transformer L4 is connected to a first output end of the high-voltage side current acquisition input terminal CN2, and a second input end of the current transformer L4 is connected to a second output end of the high-voltage side current acquisition input terminal CN 2;

the inverting input end of an amplifier U5 is respectively connected with the first end of a resistor R5, the input second end of a high-voltage side current collection output terminal CN3, the anode of a diode D3, the cathode of a diode D4 and the output first end of a current transformer L6, the non-inverting input end of the amplifier U5 is respectively connected with a power ground, the cathode of the diode D3, the anode of the diode D4 and the output second end of the current transformer L6, the output end of the amplifier U5 is respectively connected with the second end of the resistor R5 and the input first end of the high-voltage side current collection output terminal CN3, the power supply positive end of the amplifier U5 is connected with a power supply V1+, and the power supply negative end of the amplifier U5 is connected with a power supply V1-;

the inverting input end of the amplifier U4 is connected with the first end of the resistor R4, the input fourth end of the high-voltage side current collection output terminal CN3, the anode of the diode D1, the cathode of the diode D2 and the output first end of the current transformer L5 respectively, the non-inverting input end of the amplifier U4 is connected with a power ground, the cathode of the diode D1, the anode of the diode D2 and the output second end of the current transformer L5 respectively, the output end of the amplifier U4 is connected with the second end of the resistor R4 and the input third end of the high-voltage side current collection output terminal CN3 respectively, the positive power supply end of the amplifier U4 is connected with a power supply V1+, and the negative power supply end of the amplifier U4 is connected with the power supply V1-;

the inverting input end of the amplifier U3 is connected with the first end of the resistor R3, the input sixth end of the high-voltage side current collection output terminal CN3, the anode of the diode D6, the cathode of the diode D5 and the output first end of the current transformer L4 respectively, the non-inverting input end of the amplifier U3 is connected with the power ground, the cathode of the diode D6, the anode of the diode D5 and the output second end of the current transformer L4 respectively, the output end of the amplifier U3 is connected with the second end of the resistor R3 and the input fifth end of the high-voltage side current collection output terminal CN3 respectively, the power positive end of the amplifier U3 is connected with a power supply V1+, and the power negative end of the amplifier U3 is connected with the power supply V1-.

The input first end of the current transformer L3 is connected with the output fifth end of the low-voltage side current acquisition input terminal CN1, the input second end of the current transformer L3 is connected with the output sixth end of the low-voltage side current acquisition input terminal CN1, the input first end of the current transformer L2 is connected with the output third end of the low-voltage side current acquisition input terminal CN1, the input second end of the current transformer L2 is connected with the output fourth end of the low-voltage side current acquisition input terminal CN1, the input first end of the current transformer L1 is connected with the output first end of the low-voltage side current acquisition input terminal CN1, and the input second end of the current transformer L1 is connected with the output second end of the low-voltage side current acquisition input terminal CN 1;

the inverting input end of the amplifier U7 is connected with the first end of the resistor R6, the input second end of the low-voltage side current collection output terminal CN4, the anode of the diode D7, the cathode of the diode D8 and the output first end of the current transformer L3 respectively, the non-inverting input end of the amplifier U7 is connected with a power ground, the cathode of the diode D7, the anode of the diode D8 and the output second end of the current transformer L3 respectively, the output end of the amplifier U7 is connected with the second end of the resistor R6 and the input first end of the low-voltage side current collection output terminal CN4 respectively, the positive power supply end of the amplifier U7 is connected with a power supply V1+, and the negative power supply end of the amplifier U7 is connected with the power supply V1-; the inverting input end of the amplifier U8 is connected with the first end of the resistor R7, the input fourth end of the low-voltage side current collection output terminal CN4, the anode of the diode D9, the cathode of the diode D10 and the output first end of the current transformer L2 respectively, the non-inverting input end of the amplifier U8 is connected with a power ground, the cathode of the diode D9, the anode of the diode D10 and the output second end of the current transformer L2 respectively, the output end of the amplifier U8 is connected with the second end of the resistor R7 and the input third end of the low-voltage side current collection output terminal CN4 respectively, the positive power supply end of the amplifier U8 is connected with a power supply V1+, and the negative power supply end of the amplifier U8 is connected with the power supply V1-; the inverting input end of the amplifier U9 is connected with the first end of the resistor R8, the input sixth end of the low-voltage side current collection output terminal CN4, the anode of the diode D11, the cathode of the diode D12 and the output first end of the current transformer L1 respectively, the non-inverting input end of the amplifier U9 is connected with the power ground, the cathode of the diode D11, the anode of the diode D12 and the output second end of the current transformer L1 respectively, the output end of the amplifier U9 is connected with the second end of the resistor R8 and the input fifth end of the low-voltage side current collection output terminal CN4 respectively, the power positive end of the amplifier U9 is connected with a power supply V1+, and the power negative end of the amplifier U9 is connected with the power supply V1-.

Before testing, the primary side of the transformer to be tested is connected to a high-voltage side current acquisition input terminal CN2 through a lead, and the secondary side of the transformer to be tested is connected to a low-voltage side current acquisition input terminal CN1 through a lead, so that the primary side current and the secondary side current of the transformer to be tested are measured; and the high-voltage side current acquisition output terminal CN3 is connected with the high-voltage side current acquisition output terminal CN3 through the first to third plug sockets, and the low-voltage side current acquisition output terminal CN4 is connected with the fourth to sixth plug sockets, so that data are transmitted to the data acquisition card, and the acquisition of current data is realized.

In a preferred embodiment of the present invention, the first high-side voltage regulating module includes a voltage transformer U15, the first input end of the voltage transformer U15 is respectively connected to the ninth output end of the voltage acquisition input terminal U1 and the power ground, the second input end of the voltage transformer U15 is connected to the sixth output end of the voltage acquisition input terminal U1, the first output end of the voltage transformer U15 is respectively connected to the second input end of the high-side voltage acquisition output terminal CN6, the protection end of the voltage transformer U15 and the power ground, and the second output end of the voltage transformer U15 is connected to the first input end of the high-side voltage acquisition output terminal CN 6;

or/and the second low-voltage side voltage regulating module comprises a voltage transformer U10, a first input end of the voltage transformer U10 is respectively connected with a protection end of the voltage transformer U10 and a power ground, a second input end of the voltage transformer U10 is connected with a second output end of the voltage acquisition input terminal U1, a first output end of the voltage transformer U10 is respectively connected with a third input end of the low-voltage side voltage acquisition output terminal CN5 and the power ground, and a second output end of the voltage transformer U10 is connected with a fourth input end of the low-voltage side voltage acquisition output terminal CN5;

As shown in fig. 2, the current collecting circuit is specifically connected, the first input end of the voltage transformer U15 is connected to the ninth output end of the voltage collecting input terminal U1, the eighth output end of the voltage collecting input terminal U1, the seventh output end of the voltage collecting input terminal U1, the protection end of the voltage transformer U15 and the power ground, the second input end of the voltage transformer U15 is connected to the sixth output end of the voltage collecting input terminal U1, the first output end of the voltage transformer U15 is connected to the second input end of the high-voltage side voltage collecting output terminal CN6, the fourth input end of the high-voltage side voltage collecting output terminal CN6, the sixth input end of the high-voltage side voltage collecting output terminal CN6 and the power ground, and the second output end of the voltage transformer U15 is connected to the first input end of the high-voltage side voltage collecting output terminal CN 6; the first input end of the voltage transformer U14 is connected with a power ground, the second input end of the voltage transformer U14 is connected with the fifth output end of the voltage acquisition input terminal U1, the first output end of the voltage transformer U14 is connected with the power ground, and the second output end of the voltage transformer U14 is connected with the third input end of the high-voltage side voltage acquisition output terminal CN 6; the input first end of the voltage transformer U13 is connected with a power ground, the input second end of the voltage transformer U13 is connected with the output fourth end of the voltage acquisition input terminal U1, the output first end of the voltage transformer U13 is respectively connected with the protection end of the voltage transformer U13 and the power ground, and the output second end of the voltage transformer U13 is connected with the input fifth end of the high-voltage side voltage acquisition output terminal CN 6;

the input first end of the voltage transformer U12 is connected with the protection end of the voltage transformer U12 and a power ground respectively, the input second end of the voltage transformer U12 is connected with the output third end of the voltage acquisition input terminal U1, the output first end of the voltage transformer U12 is connected with the power ground, and the output second end of the voltage transformer U12 is connected with the input second end of the low-voltage side voltage acquisition output terminal CN5; the input first end of the voltage transformer U10 is respectively connected with the protection end of the voltage transformer U10 and a power ground, the input second end of the voltage transformer U10 is connected with the output second end of the voltage acquisition input terminal U1, the output first end of the voltage transformer U10 is connected with the power ground, and the output second end of the voltage transformer U10 is connected with the input fourth end of the low-voltage side voltage acquisition output terminal CN5; the first input end of the voltage transformer U11 is connected with the protection end of the voltage transformer U11 and the power ground respectively, the second input end of the voltage transformer U11 is connected with the first output end of the voltage acquisition input terminal U1, the first output end of the voltage transformer U11 is connected with the power ground, and the second output end of the voltage transformer U11 is connected with the sixth input end of the low-voltage side voltage acquisition output terminal CN 5.

Before testing, the primary side and the secondary side of the transformer to be tested are connected into a voltage acquisition input terminal U1 through conducting wires, so that the primary side voltage and the secondary side voltage of the transformer to be tested are measured; the voltage data is transmitted to the data acquisition card by connecting with the high-voltage side voltage acquisition output terminal CN6 through seven to nine plug sockets and connecting with the low-voltage side voltage acquisition output terminal CN5 through ten to twelve plug sockets, so that the voltage data acquisition is realized. The model of the high-voltage side voltage acquisition output terminal CN6 and the low-voltage side voltage acquisition output terminal CN5 can be DB128V-5.0-6P, the model of the voltage acquisition input terminal U1 can be DB128V-5.0-9P, and the model of the voltage transformers U10-15 can be TV5202.

In a preferred embodiment of the present invention, the power supply module further includes a power supply module disposed on the PCB, as shown in fig. 3, the power supply module includes an AC/DC chip unit U2, a live line end L of the AC/DC chip unit U2 is connected to a first end of the voltage dependent resistor R2 and a first end of the thermistor R1, a second end of the thermistor R1 is connected to a first input end of the power interface U6, a live line end N of the AC/DC chip unit U2 is connected to a second end of the voltage dependent resistor R2 and a second input end of the power interface U6, and a power ground end EGND of the AC/DC chip unit U2 is connected to the power ground; the positive power output terminal + V0 of the AC/DC chip unit U2 is connected with the first end of the capacitor C2, the positive power output terminal + V0 of the AC/DC chip unit U2 outputs the power supply V1+, the negative power output terminal-V0 of the AC/DC chip unit U2 is connected with the first end of the capacitor C1, the negative power output terminal-V0 of the AC/DC chip unit U2 outputs the power supply V1-, and the common end of the AC/DC chip unit U2 is respectively connected with the second end of the capacitor C1, the second end of the capacitor C2 and the power ground. The power interface U6 is connected with any phase of the primary side of the transformer to be tested and the central line through a lead, and stable voltage supply is provided for the amplifiers U3-U5 and the amplifiers U7-U9 through the AC/DC chip unit U2. The piezoresistor R2 is preferably 10D471K, and its voltage-dependent voltage is 470V. The piezoresistor is a voltage-limiting type protection device. When the voltage applied to the varistor is lower than the varistor voltage, the current flowing through it is extremely small, which corresponds to a resistance of infinite magnitude. That is, when the voltage across it is below its threshold, it behaves as an open-state switch. When the voltage applied to the varistor exceeds the varistor voltage, the current flowing through it increases sharply, which corresponds to a resistor of infinite resistance. That is, when the voltage applied to it is above its threshold, it behaves as a closed-state switch. By utilizing the nonlinear characteristic of the piezoresistor, when overvoltage appears between two poles of the piezoresistor, the piezoresistor can clamp the voltage to a relatively fixed voltage value, thereby realizing the protection of a post-stage circuit.

The thermistor R1 adopts an NTC thermistor, the model number of the thermistor is 5D-9, the room temperature (25 ℃) zero power resistance value is 5 omega, and the maximum steady-state current is 3A. An NTC thermistor, as a semiconductor device, may be used to limit an initial inrush current when a circuit is switched. When the circuit is not electrified to work, the resistance value of the thermistor at room temperature is higher, and once the power supply is switched on, the initial current is not too large. When the circuit enters a working state, the power of the thermistor is increased, the temperature is increased, the resistance value is reduced, the circuit is similar to a short-circuit state, and the circuit cannot be influenced.

the data input end of the A/D conversion module is connected with the data output end of the socket, the data output end of the A/D conversion module is connected with the A/D data input end of the controller, and the wireless data transceiving end of the controller is connected with the data transceiving end of the wireless data transceiving module; the wireless data transceiver module preferentially adopts a 5G transceiver module, and the transmission speed is high.

After the acquired analog signals are converted into digital signals, the digital signals are transmitted to a computing terminal through a wireless data transceiver module, and the running state of the transformer to be tested is computed. The method for transmitting the collected digital sequence signals (the frequency of three-phase power input by the primary side of the transformer to be measured is 50HZ, the collection of a data collection card is equal to or higher than 50HZ, fs signals are collected in total, and 10000 signals are preferentially collected) to the computing terminal (cloud server) through the wireless data transceiving module comprises the following steps:

S-A, the digital sequence signals are arranged according to time sequence and then packed into se:Sup>A datse:Sup>A packet to be uploaded, the datse:Sup>A packet to be uploaded is subjected to pre-processing to be uploaded, and the method for the pre-processing to be uploaded of the datse:Sup>A packet to be uploaded comprises the following steps:

Processing value＝MD5(data pack)，

the data pack represents a data packet to be uploaded;

MD5 () represents the MD5 algorithm in the hash function;

processing value represents a processed value;

S-B, transmitting the data packet to be uploaded and the Processing value corresponding to the data packet to be uploaded to the transfer station, and judging whether the Processing value received by the transfer station exists in the transfer station or not by the transfer station:

if the received Processing value exists in the transfer station, the transfer station does not upload the data packet to be uploaded to the cloud server;

if the received Processing value does not exist in the transfer station, the transfer station uploads the data packet to be uploaded and the Processing value corresponding to the data packet to be uploaded to the cloud server; storing the received Processing value in a transfer station database as a comparison uploading value;

S-C, the cloud server judges whether the received data packet data pack to be uploaded is the data packet data pack to be uploaded transmitted by the data acquisition card or not; the method for judging whether the received data packet to be uploaded is transmitted by the data acquisition card comprises the following steps:

Processing value ₀ ＝MD5(data pack ₀ )，

wherein, the data pack ₀ Representing a data packet to be uploaded received by a cloud server;

MD5 () represents the MD5 algorithm in the hash function;

Processing value ₀ represents a control value;

if the control value Processing value ₀ If the processing value is consistent with the processing value received by the cloud server, the cloud server analyzes the received data packet to be uploaded to obtain a digital sequence signal of the data packet;

if the control value Processing value ₀ And if the processing value is inconsistent with the processing value received by the cloud server, deleting the received data packet to be uploaded by the cloud server, and requesting the data acquisition card to send a new digital sequence signal again. The method can reduce the repeated data received by the cloud server, and improves the efficiency by deleting the repeated data through the transfer station.

the voltage data input end of the first A/D conversion high-voltage side voltage unit is connected with the seventh plug socket, the voltage data output end of the first A/D conversion high-voltage side voltage unit is connected with the first A/D voltage data input end of the controller, the voltage data input end of the second A/D conversion high-voltage side voltage unit is connected with the eighth plug socket, the voltage data output end of the second A/D conversion high-voltage side voltage unit is connected with the second A/D voltage data input end of the controller, the voltage data input end of the third A/D conversion high-voltage side voltage unit is connected with the ninth plug socket, and the voltage data output end of the third A/D conversion high-voltage side voltage unit is connected with the third A/D voltage data input end of the controller;

the voltage data input end of the first unit of the voltage at the low-voltage side of the A/D conversion is connected with the tenth plug socket, the voltage data output end of the first unit of the voltage at the low-voltage side of the A/D conversion is connected with the first input end of the voltage data at the A/D conversion, the voltage data input end of the second unit of the voltage at the low-voltage side of the A/D conversion is connected with the eleventh plug socket, the voltage data output end of the second unit of the voltage at the low-voltage side of the A/D conversion is connected with the second input end of the voltage data at the A/D conversion, the voltage data input end of the third unit of the voltage at the low-voltage side of the A/D conversion is connected with the twelfth plug socket, and the voltage data output end of the third unit of the voltage at the low-voltage side of the A/D conversion is connected with the third input end of the voltage data at the A/D conversion. The controller is convenient to identify by converting a received analog signal into a digital signal through 12 paths of A/D conversion, and the A/D conversion high-voltage side voltage first-third units, the A/D conversion low-voltage side voltage first-third units, the A/D conversion high-voltage side current first-third units and the A/D conversion low-voltage side current first-third units can adopt AD7703 type A/D converters.

s1, acquiring a primary side voltage value, a secondary side voltage value and a primary side current value of a transformer to be tested when the transformer to be tested leaves a factory; solving one or any combination characteristic quantity of a long axis, a short axis, an inclination angle and eccentricity according to the acquired primary side voltage value, secondary side voltage value and primary side current value of the transformer to be detected; forming a reference characteristic quantity set by one or any combination of the solved long axis, short axis, inclination angle and eccentricity and the corresponding delivery primary side voltage difference curve and delivery primary side current curve; in the embodiment, for example, the solved major axis, minor axis, inclination angle, eccentricity are sqrt (-2/(AA + CC + sqrt ((AA-CC) ^2+ BB ^ 2))), sqrt (-2/(AA + CC) ^2+ sqrt ((AA-CC) ^2+ BB ^ 2))), 1/2 atan (BB/(AA-CC)), ((1- ((sqrt (-2/(AA + CC) ^2 BB ^ 2))) (2) ^ 2)/((sqrt (-2/(AA + CC) ^ 2))) (1/2)), and the corresponding factory original side voltage difference curve and factory original side current curve u3_1 A22^ cos (2 × fpi ^ 1) = 11 + pi ^ 11 + AA ^ 33 ^ 11 + 11^ 11 + pi ^ 2)) (AA-11).

S2, acquiring a primary side voltage value, a secondary side voltage value and a primary side current value of the transformer to be detected during working; solving one or any combination characteristic quantity of a long axis, a short axis, an inclination angle and eccentricity according to the acquired primary side voltage value, the secondary side voltage value and the primary side current value of the transformer to be detected during working;

s11, converting a secondary side voltage value of the transformer to be tested when the transformer leaves a factory into a primary side conversion voltage value of the transformer to be tested, and calculating a primary side difference value of the transformer to be tested according to the obtained primary side conversion voltage value of the transformer to be tested; the method for calculating the difference value of the original side of the factory is as follows:

U ₂ representing the original conversion voltage value of the factory;

representing the turn ratio of the transformer to be tested;

U ₂ representing the converted voltage value of the original side of the factory;

s12, respectively fitting a factory primary side difference curve and a factory primary side current curve according to the primary side difference and the primary side current value of the transformer to be tested when the transformer is factory; in an embodiment of the present invention, a method for fitting a factory original side difference value curve includes the following steps:

s121, selecting continuous N1 primary side difference values U _3_1 from fs primary side difference values U _3_1; n1 is a positive integer less than or equal to fs and greater than or equal to 50F, F is a positive number greater than or equal to 1 and less than or equal to 200, int (50F) if 50F does not belong to Z, Z is an integer set, int () representing an integer function, e.g. when F =3.11, 50F = int (50 x 3.11) = int (155.5) =155, when F =7.71, 50F = int (50 x 7.715) = int (385.75) =385, preferably N1 fs =10000; f1=150.

S122, performing fast Fourier transform on the selected continuous N1 primary side difference values U _3_1 to obtain voltage difference frequency domain signals; the method for calculating the voltage difference frequency domain signal comprises the following steps:

S2＝fft(U_3_1,N1)，

wherein fft represents a fast fourier transform function;

fft (U _3_1, N1) indicates that N1 primary side difference values U _3_1 are input into a fast Fourier transform function and transformed into frequency domain signals;

s2, representing a voltage difference frequency domain signal;

s123, extracting a phase angle with the frequency of f1 in the voltage difference frequency domain signal; the phase angle calculation method comprises the following steps:

AV1＝angle(S2(f1*N1/fs+1))，

f1 represents frequency;

n1 represents the total number of sampling of the primary side difference value U _3_1;

fs represents the total number of the continuous primary side difference values U _3_1;

s2 (f 1 × N1/fs + 1) represents voltage array data at the frequency domain signal position of the voltage difference f1 × N1/fs +1, that is, voltage array data at the frequency f 1; when S2 (1) represents voltage array data with frequency 0, when S2 (2) represents voltage array data with frequency 1, when S2 (3) represents voltage array data with frequency 2, when S2 (4) represents voltage array data with frequency 3, … …, and when S2 (f 1 × N1/fs + 1) represents voltage array data with frequency f1 × N1/fs.

angle () represents the extraction phase angle function;

AV1 represents a phase angle;

s124, extracting an amplitude with the frequency of f1 in the voltage difference frequency domain signal; the amplitude value calculation method comprises the following steps:

MU_3_1＝abs(S2(f1*N1/fs+1))*2/N1，

f1 represents frequency;

n1 represents the total number of the sampling of the primary side difference value U _3_1;

s2 (f 1 × N1/fs + 1) represents array data at a position of f1 × N1/fs + 1; that is, voltage array data with frequency f 1; when S2 (1) represents voltage array data with frequency 0, when S2 (2) represents voltage array data with frequency 1, when S2 (3) represents voltage array data with frequency 2, when S2 (4) represents voltage array data with frequency 3, … …, when S2 (f 1 × N1/fs + 1) represents voltage array data with frequency f1 × N1/fs.

abs () represents the extracted magnitude function;

MU _3_1 denotes amplitude;

s125, obtaining a difference curve of the original side of the factory according to the phase angle and the amplitude, wherein the expression of the difference curve of the original side of the factory is as follows:

u3_1＝MU_3_1*cos(2*pi*f1*t+AV1)，

wherein u3_1 represents a difference curve of the original side of the factory;

MU _3_1 denotes amplitude;

pi represents a circumferential ratio pi

f1 represents frequency;

t represents a time;

AV1 denotes a phase angle.

The method for fitting the factory original side current curve comprises the following steps:

s121, selecting continuous N1 primary side current values I1_1 from fs primary side current values I1_1; n1 is a positive integer less than or equal to fs and greater than or equal to 50F, F is a positive number greater than or equal to 1 and less than or equal to 200, int (50F) if 50F does not belong to Z, Z is an integer set, int () representing an integer function, e.g. when F =3.11, 50F = int (50 x 3.11) = int (155.5) =155, when F =7.71, 50F = int (50 x 7.715) = int (385.75) =385, preferably N1 fs =10000; f1=150..

S122, performing fast Fourier transform on the selected continuous N1 primary side current values I1_1 to obtain current frequency domain signals of the primary side current values; the calculation method of the current frequency domain signal comprises the following steps:

S1＝fft(I1_1,N1)，

wherein fft represents a fast fourier transform function;

fft (I1 _1, N1) represents that N1 primary side current values I1_1 are input into a fast Fourier transform function and are transformed into frequency domain signals;

s1 represents a current frequency domain signal;

s123, extracting a phase angle with the frequency of f1 in the current frequency domain signal; the phase angle calculation method comprises the following steps:

AI1＝angle(S1(f1*N1/fs+1))，

f1 represents frequency;

n1 represents the total number of the primary side current value I1_1 samples;

fs represents the total number of the selected continuous primary side current values I1_1;

s1 (f 1 × N1/fs + 1) represents current array data at a current frequency domain signal position of f1 × N1/fs +1, that is, current array data at a frequency of f 1; when S1 (1) represents current array data with frequency 0, when S1 (2) represents current array data with frequency 1, when S1 (3) represents current array data with frequency 2, when S1 (4) represents current array data with frequency 3, … …, and when S1 (f 1N 1/fs + 1) represents current array data with frequency f 1N 1/fs.

angle () represents the extraction phase angle function;

AI1 represents a phase angle;

s124, extracting the amplitude with the frequency f1 from the current frequency domain signal; the amplitude value calculation method comprises the following steps:

MI1_1＝abs(S1(f1*N1/fs+1))*2/N1，

f1 represents frequency;

n1 represents the total number of the primary side current value I1_1 samples;

fs represents the total number of the continuous primary side current values I1_1;

s1 (f 1 × N1/fs + 1) represents current array data at a position of f1 × N1/fs +1, that is, current array data having a frequency of f 1; when S1 (1) represents the current array data with frequency 0, when S1 (2) represents the current array data with frequency 1, when S1 (3) represents the current array data with frequency 2, when S1 (4) represents the current array data with frequency 3, … …, when S1 (f 1N 1/fs + 1) represents the current array data with frequency f 1N 1/fs.

abs () represents the extracted magnitude function;

MI1_1 represents the amplitude;

s125, obtaining a primary side current curve according to the phase angle and the amplitude, wherein the expression of the primary side differential current is as follows:

i1_1＝MI1_1*cos(2*pi*f1*t+AI1)，

wherein i1_1 represents a primary side current curve;

MI1_1 represents amplitude;

pi represents a circumferential ratio pi

f1 represents frequency;

t represents a time;

AI1 represents a phase angle;

and S13, calculating to obtain one or any combination characteristic quantity of the major axis, the minor axis, the inclination angle and the eccentricity of the ellipse by using the difference curve of the factory original side and the current curve of the factory original side obtained by fitting. The method for calculating the major axis, the minor axis, the inclination angle and the eccentricity of the ellipse comprises the following steps:

s131, calculating the angle difference between the voltage and the current, wherein the calculation method of the angle difference between the voltage and the current comprises the following steps:

jiaodu_1＝AV1-AI1，

AV1 represents a voltage phase angle;

AI1 represents the current phase angle;

jiaodu _1 represents an angle difference;

s131, let A1= MI1_1, A2= MU _3_1, A3= jiaodu _1;

s132, calculating an intermediate first parameter, wherein the calculation method of the intermediate first parameter comprises the following steps:

A＝-1/((A1^2)*((sin(A3))^2))，

wherein A1 represents a current amplitude;

a3 represents an angle difference;

a represents an intermediate first parameter;

s132, calculating an intermediate second parameter, wherein the calculation method of the intermediate second parameter is as follows:

B＝2*cos(A3)/(A1*A2*(sin(A3))^2)，

wherein A3 represents an angle difference;

a1 represents a current amplitude;

a2 represents a voltage amplitude;

b represents an intermediate second parameter;

s132, calculating an intermediate third parameter, wherein the calculation method of the intermediate third parameter is as follows:

C＝-1/((A2^2)*((sin(A3))^2))，

wherein A2 represents a voltage amplitude;

a3 represents an angle difference;

c represents an intermediate third parameter;

s132, the long axis calculation method comprises the following steps:

a＝sqrt(-2/(A+C+sqrt((A-C)^2+B^2)))，

the short axis calculation method comprises the following steps:

b＝sqrt(-2/(A+C-sqrt((A-C)^2+B^2)))，

the calculation method of the inclination angle comprises the following steps:

c＝1/2*atan(B/(A-C))，

the calculation method of the eccentricity comprises the following steps:

e＝((1-(b^2)/(a^2))^(1/2)。

in a preferred embodiment of the present invention, in step S2, the method for solving one or any combination of feature quantities of a long axis, a short axis, an inclination angle and an eccentricity according to the primary side voltage value and the secondary side voltage value of the transformer to be tested and the primary side current value during operation includes the following steps:

U ₂ "represents the value of the primary side switching voltage;

representing the turn ratio of the transformer to be tested;

is represented by

The reciprocal of (a);

U ₂ "represents the value of the primary side switching voltage;

s22, respectively fitting a working primary side difference curve and a working primary side current curve according to the primary side difference and the primary side current value of the transformer to be measured during working; the calculation method of the working primary side difference curve and the working primary side current curve is the same as the calculation method of the factory primary side difference curve and the factory primary side current curve, the number of N1= fs can be set according to the actual number, preferably N1= fs =5000, and the calculation amount is reduced.

The invention also provides a third harmonic-based on-line monitoring method for the deformation of the Lissajous figure transformer winding, which comprises the following steps:

and if the difference value between one or any combination characteristic quantity of the long axis, the short axis, the inclination angle and the eccentricity in the step S2 and one or any combination characteristic quantity of the long axis, the short axis, the inclination angle and the eccentricity in the reference characteristic quantity set in the step S3 is not within the preset range, the winding of the transformer to be tested is abnormal, and the position of the transformer to be tested is sent to a maintenance worker. In the embodiment, a-a0 ≧ a1, where a represents the long axis value, a0 represents the preset long axis deviation threshold, and a1 represents the preset long axis range threshold; the transformer winding to be tested is abnormal; otherwise, the winding of the transformer to be tested is normal.

If b-b0 ≧ b1, where b represents a minor axis value, b0 represents a preset minor axis deviation threshold, b1 represents a preset minor axis range threshold; the transformer winding to be tested is abnormal; otherwise, the transformer winding to be tested is normal; if c-c0 ≧ c1, where c represents a tilt angle value, c0 represents a preset tilt angle deviation threshold, and c1 represents a preset tilt angle range threshold; the transformer winding to be tested is abnormal; otherwise, the transformer winding to be tested is normal; if e-e0 is not less than e1, wherein e represents eccentricity, e0 represents a preset eccentricity deviation threshold value, and e1 represents a preset eccentricity range threshold value; the transformer winding to be tested is abnormal; otherwise, the winding of the transformer to be tested is normal.

wherein, U represents the voltage value of the primary side of the transformer to be tested when the transformer leaves the factory;

U ₂ ' represents a factory secondary side conversion voltage value;

to represent

The reciprocal of (a);

wherein, delta U' represents the difference value of the auxiliary leaving factory side;

U ₂ ' represents a factory secondary side conversion voltage value;

U ₁ the secondary side voltage value of the transformer to be tested when leaving the factory is represented;

wherein, U ₁ "represents a value of the secondary side switching voltage;

representing the turn ratio of the transformer to be tested;

is represented by

The reciprocal of (a);

U ₁ "represents a value of the secondary side switching voltage;

s22, fitting a working secondary side difference value curve and a working secondary side current curve respectively according to the secondary side difference value and the secondary side current value of the transformer to be detected during working;

While embodiments of the invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. A Lissajous figure transformer winding deformation online monitoring method based on third harmonic is characterized by comprising the following steps:

if the difference value between one or any combination characteristic quantity of the long axis, the short axis, the inclination angle and the eccentricity in the step S2 and one or any combination characteristic quantity of the long axis, the short axis, the inclination angle and the eccentricity in the reference characteristic quantity set in the step S3 is not within a preset range, the transformer winding to be tested is abnormal, and early warning and transformer position information are sent;

in step S1, the method for solving one or any combination of characteristic quantities of a long axis, a short axis, an inclination angle and an eccentricity according to the acquired primary side voltage value, secondary side voltage value and primary side current value of the transformer to be measured includes the following steps:

s11, converting a secondary side voltage value of the transformer to be tested when the transformer leaves a factory into a primary side conversion voltage value of the transformer, and calculating a primary side difference value of the transformer according to the obtained primary side conversion voltage value of the transformer; the method for calculating the difference value of the original side of the factory is as follows:

U ₂ representing the original conversion voltage value of the factory;

representing the turn ratio of the transformer to be tested;

s12, respectively fitting a factory primary side difference curve and a factory primary side current curve according to the primary side difference and the primary side current value of the transformer to be tested when the transformer is factory; the method for fitting the difference value curve of the factory original side comprises the following steps:

s121, selecting continuous N1 primary side difference values U _3_1 from fs primary side difference values U _3_1; n1 is a positive integer less than or equal to fs and greater than or equal to 50 f, f is a positive number greater than or equal to 1 and less than or equal to 200, if 50 f does not belong to Z, Z is an integer set, then int (50 f), int () represents an integer function, f1=150;

S2＝fft(U_3_1,N1)，

wherein fft represents a fast fourier transform function;

s2, representing a voltage difference frequency domain signal;

s123, extracting a phase angle with the frequency of f1 from the voltage difference frequency domain signal; the phase angle calculation method comprises the following steps:

AV1＝angle(S2(f1*N1/fs+1))，

f1 represents a frequency;

s2 (f 1 × N1/fs + 1) represents voltage array data at a voltage difference frequency domain signal position of f1 × N1/fs + 1;

angle () represents the extraction phase angle function;

AV1 represents a phase angle;

s124, extracting the amplitude with the frequency of f1 from the voltage difference frequency domain signal; the amplitude value calculation method comprises the following steps:

MU_3_1＝abs(S2(f1*N1/fs+1))*2/N1，

f1 represents frequency;

s2 (f 1 × N1/fs + 1) represents array data at a position of f1 × N1/fs + 1;

abs () represents an extraction magnitude function;

MU _3_1 denotes amplitude;

u3_1＝MU_3_1*cos(2*pi*f1*t+AV1)，

wherein u3_1 represents a difference curve of the original side of the factory;

MU _3_1 denotes amplitude;

pi represents a circumferential ratio pi

f1 represents frequency;

t represents a time;

AV1 represents a phase angle;

s121, selecting continuous N1 primary side current values I1_1 from fs primary side current values I1_1; n1 is a positive integer less than or equal to fs and greater than or equal to 50F, F is a positive number greater than or equal to 1 and less than or equal to 200, if 50F does not belong to Z, Z is an integer set, then int (50F), int () represents an integer function;

S1＝fft(I1_1,N1)，

wherein fft represents a fast fourier transform function;

s1 represents a current frequency domain signal;

s123, extracting a phase angle with the frequency of f1 from the current frequency domain signal; the phase angle calculation method comprises the following steps:

AI1＝angle(S1(f1*N1/fs+1))，

f1 represents frequency;

n1 represents the total number of sampling of the primary side current value I1_1;

s1 (f 1 × N1/fs + 1) represents current array data with the current frequency domain signal position f1 × N1/fs + 1;

angle () represents the extraction phase angle function;

AI1 represents a phase angle;

MI1_1＝abs(S1(f1*N1/fs+1))*2/N1，

f1 represents frequency;

s1 (f 1 × N1/fs + 1) represents current array data at a position of f1 × N1/fs + 1;

abs () represents the extracted magnitude function;

MI1_1 represents the amplitude;

s125, obtaining a primary side current curve according to the phase angle and the amplitude, wherein the expression of the primary side differential current is as follows: i1_1= MI1 _1cos (2 pi f1 t + AI1),

wherein i1_1 represents a primary side current curve;

MI1_1 represents amplitude;

pi represents a circumferential ratio pi

f1 represents frequency;

t represents a time;

AI1 represents the phase angle.