CN111537785A - A three-phase secondary circuit no-load on-line inspection tester - Google Patents

Abstract

The invention relates to a three-phase secondary loop no-load on-line inspection tester. It mainly solves the technical problems that the existing electric energy meter no-load measurement online inspection test instrument cannot provide a complete phasor diagram and has no phasor diagram database. The technical scheme of the present invention is: it consists of an input signal circuit, a current signal analog-to-digital conversion circuit, a voltage signal analog-to-digital conversion circuit, a voltage and current signal phase measurement circuit and an LCD liquid crystal screen, and the current signal output end of the input signal circuit and The voltage signal output terminal is connected to the input terminal of the current signal analog-to-digital conversion circuit and the input terminal of the voltage signal analog-to-digital conversion circuit, and the output terminal of the current signal analog-to-digital conversion circuit is connected to the current signal input of the voltage-current signal phase measurement circuit The output end of the voltage signal analog-to-digital conversion circuit is connected to the voltage signal input end of the voltage and current signal phase measurement circuit, and the display signal output end of the voltage and current signal phase measurement circuit is connected to the LCD liquid crystal screen.

Description

A three-phase secondary circuit no-load on-line inspection tester

technical field

The invention belongs to the technical field of electric energy measurement and detection, and in particular relates to a three-phase secondary circuit no-load on-line inspection tester.

Background technique

The secondary circuit of the power grid is generally mainly composed of current transformers, voltage transformers, electric energy meters, etc. During online inspection of the three-phase secondary circuit, it is often encountered that the line is no-load or light-load creeping, and the existing instruments cannot detect it. In the above situation, the electric energy meter shows that the current is only a few mA. Existing electric energy meter testing instruments cannot judge online whether the polarity and phase of the wiring circuit of the transformer and electric energy meter are correct, whether the nature of the external load has changed, and whether each component is working normally. Chinese patent ZL201720352457.8 discloses an online inspection tester for no-load measurement of electric energy meters. The tester measures whether there is no-load by converting the angle difference into phase angle. For the phasor diagram, the power supply mode of the instrument is still the mains or battery power supply mode, and there is no phasor diagram database.

SUMMARY OF THE INVENTION

The purpose of the present invention is to solve the technical problem of the existing no-load measurement online inspection tester of electric energy meters that cannot provide a complete phasor diagram and no phasor diagram database, and provides a three-phase secondary loop no-load online inspection. tester.

For achieving the above object, the technical scheme adopted in the present invention is:

A three-phase secondary loop no-load on-line inspection tester is composed of an input signal circuit, a current signal analog-to-digital conversion circuit, a voltage signal analog-to-digital conversion circuit, a voltage and current signal phase measurement circuit and an LCD liquid crystal screen. The current signal output end of the signal circuit is connected to the input end of the current signal analog-to-digital conversion circuit, the voltage signal output end of the input signal circuit is connected to the input end of the voltage signal analog-to-digital conversion circuit, and the current signal analog-to-digital conversion circuit is connected. The output end of the digital conversion circuit is connected with the current signal input end of the voltage and current signal phase measurement circuit, the output end of the voltage signal analog-to-digital conversion circuit is connected with the voltage signal input end of the voltage and current signal phase measurement circuit, the voltage and current signal The display signal output end of the phase measuring circuit is connected with the LCD liquid crystal screen.

Further, the input signal circuit consists of A-phase aerial plug L1, B-phase aerial plug L2, C-phase aerial plug L3, power input transformer B1, switching power supply UR, power switch K, three voltage loop transformers B2, B3 and B4, three current loop isolation transformers B5, B6 and B7, three-phase secondary voltage conversion relay J1, three voltage and current loop relays J2, J3 and J4 and two diodes D1 and D2. Pins 1 and 2 of the plug L1 are connected to the primary of the power input transformer B1 and the primary of the first voltage loop transformer B2, and the pins 3 and 4 of the A-phase aerial plug L1 are connected to the first current loop isolation transformer B5 The primary connection of the B-phase aerial plug L2 is connected with the primary connection of the second voltage loop transformer B3, and the 3-pin and 4-pin of the B-phase aerial plug L2 are isolated from the second current loop The primary connection of transformer B6, pins 1 and 2 of the C-phase aerial plug L3 are connected to the primary of the third voltage loop transformer B4, and pins 3 and 4 of the C-phase aerial plug L3 are connected to the third current The primary of the loop isolation transformer B7 is connected, the secondary of the power input transformer B1 is connected to the input end of the switching power supply UR, and the power switch K is set on the line between the secondary of the power input transformer B1 and the input end of the switching power supply UR, so One end of the secondary of the three voltage loop transformers B2, B3 and B4 is connected to the normally closed contact of the three-phase secondary voltage switching relay J1, and the moving contact of the three-phase secondary voltage switching relay J1 is connected to the normally closed contact of the three-phase secondary voltage switching relay J1. One normally open contact of the three voltage and current loop relays J2, J3 and J4 is connected, and the intermediate terminals of the secondary of the three voltage loop transformers B2, B3 and B4 are connected with the three-phase secondary voltage switching relay J1. The normally open contacts are connected, the other ends of the secondary of the three voltage loop transformers B2, B3 and B4 are grounded, and the secondary ends of the three current loop isolation transformers B5, B6 and B7 are connected to the three voltage The other normally open contacts of the current loop relays J2, J3 and J4 are connected, the other secondary ends of the three current loop isolation transformers B5, B6 and B7 are grounded, and the three voltage current loop relays J2, J3 and J4 A voltage signal output terminal u is formed after one moving contact of the three voltage and current loop relays J2, J3 and J4 is connected to form a current signal output terminal i, the first diode D1 The positive electrode of the first diode D1 is connected to the negative electrode of the second diode D2 and then connected to the current signal output terminal i. The negative electrode of the first diode D1 is connected to the positive electrode of the second diode D2 and then grounded to form the voltage limiting of the current loop. loop.

Further, the current signal analog-to-digital conversion circuit is composed of 15 resistors R1-R15, a first variable resistor RP1, 5 operational amplifiers OP1-OP5 and two capacitors C1 and C2. One end of the first resistor R1 It is connected to the current signal output end i of the input signal circuit, the other end of the first resistor R1 is connected to the 3 pin of the first operational amplifier OP1, the 6 pin of the first operational amplifier OP1 is connected to one end of the second resistor R2 and the One end of the fourth resistor R4 is connected, the second pin of the first operational amplifier OP1 is connected to the other end of the second resistor R2 and one end of the third resistor R3, the other end of the third resistor R3 is grounded, and the fourth The other end of the resistor R4 is connected to pin 3 of the second operational amplifier OP2, the pin 6 of the second operational amplifier OP2 is connected to one end of the fifth resistor R5 and one end of the seventh resistor R7, and the second operational amplifier OP2 Pin 2 is connected to the other end of the fifth resistor R5 and one end of the sixth resistor R6, the other end of the sixth resistor R6 is grounded, the other end of the seventh resistor R7 is connected to one end of the eighth resistor R8, the first capacitor One end of C1 is connected to one end of the second capacitor C2, the other end of the second capacitor C2 is connected to pin 2 of the third operational amplifier OP3 and one end of the ninth resistor R9, and pin 6 of the third operational amplifier OP3 is connected to The other end of the first capacitor C1, a fixed end and a movable end of the first variable resistor RP1 are connected to one end of the eleventh resistor R11, and the other fixed end of the first variable resistor RP1 is connected to the ninth resistor R9. The other end is connected, the third pin of the third operational amplifier OP3 is grounded through the tenth resistor R10, the other end of the eighth resistor R8 is grounded, and the other end of the eleventh resistor R11 is connected to the fourth operational amplifier OP4. The pin 2 of the fourth operational amplifier OP4 is grounded through the twelfth resistor R12, the pin 6 of the fourth operational amplifier OP4 is connected to the pin 2 of the fifth operational amplifier OP5 through the thirteenth resistor R13, and the Pin 3 of the fifth operational amplifier OP5 is grounded through the fourteenth resistor R14, pin 1 of the fifth operational amplifier OP5 is grounded, and pin 4 of the fifth operational amplifier OP5 is connected to the -5V power supply of the switching power supply UR in the input signal circuit connection, the 5th, 6th and 8th pins of the fifth operational amplifier OP5 are connected through the fifteenth resistor R15 and the 7th pin of the fifth operational amplifier OP5 is connected to form the output end of the current signal fi, and the 5th pin of the fifth operational amplifier OP5 is connected. , 6 and 8 pins are also connected with the +5V power supply of the switching power supply UR in the input signal circuit.

Further, the voltage signal analog-to-digital conversion circuit consists of nine resistors R16-R24, second and third variable resistors RP2, RP3, four operational amplifiers OP6-OP9, two capacitors C3, C4 and analog-to-digital converters. A/D composition, one end of the sixteenth resistor R16 is connected to the voltage signal output end u of the input signal circuit, the other end of the sixteenth resistor R6 is connected to the 3rd pin of the sixth operational amplifier OP6, the first Pin 6 of the six operational amplifiers OP6 is connected to a fixed end of the second variable resistor RP2 and one end of the third capacitor C3 and the fourth capacitor C4, and pin 2 of the sixth operational amplifier OP6 is connected to one end of the seventeenth resistor R17 It is connected to the other fixed end and the movable end of the second variable resistor RP2, the other end of the seventeenth resistor R17 is grounded, and the other end of the fourth capacitor C4 is connected to the second and tenth pins of the seventh operational amplifier OP7. One end of the eighth resistor R18 is connected, and the 6th pin of the seventh operational amplifier OP7 is connected with the other end of the third capacitor C3, a fixed end and a movable end of the third variable resistor RP3 and one end of the twentieth resistor R20, so The other fixed end of the third variable resistor RP3 is connected to the other end of the eighteenth resistor R18, the pin 3 of the seventh operational amplifier OP7 is grounded through the nineteenth resistor R19, and the pin 6 of the seventh operational amplifier OP7 is grounded. The pin is also connected to the CH0 pin of the analog-to-digital converter A/D, the other end of the twentieth resistor R20 is connected to the 3th pin of the eighth operational amplifier OP8, and the 2th pin of the eighth operational amplifier OP8 passes through the twentieth A resistor R21 is grounded, pin 6 of the eighth operational amplifier OP8 is connected to pin 2 of the ninth operational amplifier OP9 through the twenty-second resistor R22, and pin 3 of the ninth operational amplifier OP9 is connected through the twenty-third resistor R23 Grounding, pin 1 of the ninth operational amplifier OP9 is grounded, pin 4 of the ninth operational amplifier OP9 is connected to the -5V power supply of the switching power supply UR in the input signal circuit, and pins 5, 6 and 5 of the ninth operational amplifier OP9 After the 8-pin is connected, the 24th resistor R24 is connected with the 7th pin of the ninth operational amplifier OP9 to form the output terminal of the voltage signal fu. The 5th, 6th and 8th pins of the ninth operational amplifier OP9 are also connected with the switching power supply in the input signal circuit. +5V power connection for UR.

Further, the voltage and current signal phase measurement circuit is composed of a NAND gate logic chip U, a counter HM, a microprocessor MCU, a crystal oscillator XTAL, 5 capacitors C5 to C9 and a resistor R25. Pins 1 and 2 are connected to the voltage signal fu output end of the voltage signal analog-to-digital conversion circuit, and the 5th pin of the NAND gate logic chip U is connected to the current signal fi output end of the current signal analog-to-digital conversion circuit. The 11-pin of the gate logic chip U is connected with the 10-pin of the counter HM, the 13-pin of the NAND gate logic chip U is connected with the 15-pin of the microprocessor MCU, and the 11-pin of the counter HM is connected with the 14-pin of the microprocessor MCU. The pins 9, 7, 6, 5, 3, 2, 4, and 13 of the counter HM are respectively connected with pins 1 to 8 of the microprocessor MCU, and the 16 pins of the counter HM are connected to the switch in the input signal circuit. The 5V power supply of the power supply UR is connected, the 8 pin of the counter HM is grounded, one end of the crystal oscillator XTAL is connected to the 19 pin of the microprocessor MCU and one end of the ninth capacitor C9, and the other end of the crystal oscillator XTAL is connected to the microprocessor MCU. The 18th pin is connected to one end of the eighth capacitor C8, the other end of the eighth capacitor C8 and the other end of the ninth capacitor C9 are grounded, and the WR and RD pins of the microprocessor MCU are connected to the input end of the LCD liquid crystal screen, so Pin 13 of the microprocessor MCU is connected to the current signal fi output end of the current signal analog-to-digital conversion circuit, and pin 12 of the microprocessor MCU is connected to the voltage signal fu output end of the voltage signal analog-to-digital conversion circuit. Pin 9 of the processor MCU is connected to one end of the twenty-fifth resistor R25 and one end of the seventh capacitor C7, and pin 40 of the microprocessor MCU is connected to one end of the fifth capacitor C5, one end of the sixth C6 and the VCC power supply , the pin 20 of the microprocessor MCU is connected to the other end of the fifth capacitor C5 and the other end of the sixth C6 and then grounded, the other end of the seventh capacitor C7 is connected to the VCC power supply, and the twenty-fifth resistor The other end of R25 is grounded.

The beneficial effects of the present invention are:

1. In the present invention, the input voltage and current signals are all isolated and conditioned by the transformer to obtain pure sine wave signals, so as to avoid misjudgment of the user circuit caused by clutter or harmonic misdetection;

2. The present invention accurately amplifies and filters the voltage signal and the current signal. By directly measuring the phase angle, the range is 0 to ±180°, covering 360°, so that the data is more real and effective, the displayed image is real and reliable, and the judgment is more accurate. By comparing the images The database can know what is wrong wiring and how to make up the power;

3. In the present invention, the weak current signal is amplified 1 million times by a multi-stage high-fidelity amplifier under no-load state, and sequence and logic operations are performed under the control of a microprocessor to accurately measure the phase of voltage and current and the magnitude of voltage;

4. The present invention directly obtains electricity through the test loop, and supplies the switching power supply through conversion and conditioning, so that the on-site commercial power cannot be obtained or the battery is insufficiently charged.

Description of drawings

Fig. 1 is the input signal circuit diagram of the present invention;

Fig. 2 is the current signal analog-to-digital conversion circuit diagram of the present invention;

Fig. 3 is the voltage signal analog-to-digital conversion circuit diagram of the present invention;

FIG. 4 is a circuit diagram of the voltage and current signal phase measurement circuit and the LCD display screen of the present invention.

Detailed ways

The present invention will be further described below with reference to the accompanying drawings and embodiments.

As shown in Figures 1 to 4, a three-phase secondary loop no-load on-line inspection tester in this embodiment consists of an input signal circuit, a current signal analog-to-digital conversion circuit, a voltage signal analog-to-digital conversion circuit, a voltage The current signal phase measurement circuit is composed of an LCD liquid crystal screen, the current signal output end of the input signal circuit is connected with the input end of the current signal analog-to-digital conversion circuit, and the voltage signal output end of the input signal circuit is connected with the voltage signal The input end of the analog-to-digital conversion circuit is connected, the output end of the current signal analog-to-digital conversion circuit is connected to the current signal input end of the voltage and current signal phase measurement circuit, and the output end of the voltage signal analog-to-digital conversion circuit is connected with the voltage and current signal phase. The voltage signal input end of the measuring circuit is connected, and the display signal output end of the voltage and current signal phase measuring circuit is connected with the LCD liquid crystal screen.

As shown in Figure 1, the input signal circuit consists of A-phase aerial plug L1, B-phase aerial plug L2, C-phase aerial plug L3, power input transformer B1, switching power supply UR, power switch K, and three voltage loop transformers B2, B3 and B4, three current loop isolation transformers B5, B6 and B7, three-phase secondary voltage conversion relay J1, three voltage and current loop relays J2, J3 and J4 and two diodes D1 and D2. Pins 1 and 2 of the A-phase aerial plug L1 are connected to the primary of the power input transformer B1 and the primary of the first voltage loop transformer B2, and pins 3 and 4 of the A-phase aerial plug L1 are connected to the first current loop The primary connection of the isolation transformer B5, the 1-pin and 2-pin of the B-phase aerial plug L2 are connected with the primary of the second voltage loop transformer B3, and the 3-pin and 4-pin of the B-phase aerial plug L2 are connected with the second The primary connection of the current loop isolation transformer B6, the 1-pin and 2-pin of the C-phase aerial plug L3 are connected with the primary of the third voltage loop transformer B4, and the 3-pin and 4-pin of the C-phase aerial plug L3 are connected with The primary of the third current loop isolation transformer B7 is connected, the secondary of the power input transformer B1 is connected to the input end of the switching power supply UR, and the power switch K is set on the line between the secondary of the power input transformer B1 and the input end of the switching power supply UR On the other hand, one end of the secondary of the three voltage loop transformers B2, B3 and B4 is connected to the normally closed contact of the three-phase secondary voltage conversion relay J1, and the movement of the three-phase secondary voltage conversion relay J1 The contact is connected to a normally open contact of the three voltage-current loop relays J2, J3 and J4, the intermediate terminals of the secondary of the three voltage-loop transformer converters B2, B3 and B4 are converted with the three-phase secondary voltage The normally open contact of the relay J1 is connected, the other ends of the secondary of the three voltage loop transformers B2, B3 and B4 are grounded, and the secondary ends of the three current loop isolation transformers B5, B6 and B7 are connected to the ground. The other normally open contacts of the three voltage and current loop relays J2, J3 and J4 are connected, the other secondary ends of the three current loop isolation transformers B5, B6 and B7 are grounded, and the three voltage and current loop relays J2, One moving contact of J3 and J4 is connected to form a voltage signal output terminal u, and the other moving contacts of the three voltage and current circuit relays J2, J3 and J4 are connected to form a current signal output terminal i, the first two The anode of the pole tube D1 is connected to the cathode of the second diode D2 and then connected to the current signal output terminal i. The cathode of the first diode D1 is connected to the anode of the second diode D2 and then grounded to form a current loop. pressure limiting circuit. The three voltage loop transformers B2, B3 and B4 are secondary double taps, the first tap is 100/√3V/2V, and the second tap is 100V/2V; the three current loop isolation transformers B5, B6 and B7 are 1:1 isolation transformers; the three-phase secondary voltage conversion relay J1 is 3Z 0.01A; the three voltage and current loop relays J2, J3 and J4 are 2Z 0.01A. The A-phase aerial plug L1 can be connected to the three-phase three-wire secondary circuit voltage uab or the three-phase four-wire secondary circuit voltage ua or the single-phase secondary circuit voltage u according to the actual situation of the test grid; the C-phase aerial plug L3 According to the actual situation of the test grid, it can be connected to the three-phase three-wire secondary circuit voltage uca or the three-phase four-wire secondary circuit voltage uc; the B-phase aerial plug L2 can be connected to the three-phase four-wire secondary circuit according to the actual situation of the test grid voltage ub.

As shown in Figure 2, the current signal analog-to-digital conversion circuit is composed of 15 resistors R1-R15, a first variable resistor RP1, 5 operational amplifiers OP1-OP5 and two capacitors C1 and C2. The first resistor One end of R1 is connected to the current signal output end i of the input signal circuit, the other end of the first resistor R1 is connected to the 3 pin of the first operational amplifier OP1, and the 6 pin of the first operational amplifier OP1 is connected to the second resistor R2 One end of the first operational amplifier OP1 is connected to one end of the fourth resistor R4, the second pin of the first operational amplifier OP1 is connected to the other end of the second resistor R2 and one end of the third resistor R3, and the other end of the third resistor R3 is grounded, so The other end of the fourth resistor R4 is connected to pin 3 of the second operational amplifier OP2, the pin 6 of the second operational amplifier OP2 is connected to one end of the fifth resistor R5 and one end of the seventh resistor R7, and the second operational amplifier OP2 is connected to one end of the fifth resistor R5 and one end of the seventh resistor R7. Pin 2 of the amplifier OP2 is connected to the other end of the fifth resistor R5 and one end of the sixth resistor R6, the other end of the sixth resistor R6 is grounded, and the other end of the seventh resistor R7 is connected to one end of the eighth resistor R8, One end of the first capacitor C1 is connected to one end of the second capacitor C2, the other end of the second capacitor C2 is connected to pin 2 of the third operational amplifier OP3 and one end of the ninth resistor R9, and the third operational amplifier OP3 is connected to one end of the ninth resistor R9. Pin 6 is connected to the other end of the first capacitor C1, a fixed end and a movable end of the first variable resistor RP1, and one end of the eleventh resistor R11, and the other fixed end of the first variable resistor RP1 is connected to the ninth The other end of the resistor R9 is connected to the ground, the third pin of the third operational amplifier OP3 is grounded through the tenth resistor R10, the other end of the eighth resistor R8 is grounded, and the other end of the eleventh resistor R11 is connected to the fourth operational amplifier. Pin 3 of OP4 is connected, pin 2 of the fourth operational amplifier OP4 is grounded through the twelfth resistor R12, and pin 6 of the fourth operational amplifier OP4 is connected to pin 2 of the fifth operational amplifier OP5 through the thirteenth resistor R13 , pin 3 of the fifth operational amplifier OP5 is grounded through the fourteenth resistor R14, pin 1 of the fifth operational amplifier OP5 is grounded, and pin 4 of the fifth operational amplifier OP5 is connected to the switch power supply UR in the input signal circuit. -5V power supply connection, the 5th, 6th and 8th pins of the fifth operational amplifier OP5 are connected and then connected to the 7th pin of the fifth operational amplifier OP5 through the fifteenth resistor R15 to form the current signal fi output end, the fifth operational amplifier Pins 5, 6 and 8 of OP5 are also connected to the +5V power supply of the switching power supply UR in the input signal circuit.

As shown in Figure 3, the voltage signal analog-to-digital conversion circuit consists of nine resistors R16-R24, second and third variable resistors RP2, RP3, four operational amplifiers OP6-OP9, two capacitors C3, C4 and analog A digital converter A/D is formed, one end of the sixteenth resistor R16 is connected to the voltage signal output end u of the input signal circuit, and the other end of the sixteenth resistor R6 is connected to the 3th pin of the sixth operational amplifier OP6, Pin 6 of the sixth operational amplifier OP6 is connected to a fixed end of the second variable resistor RP2 and one end of the third capacitor C3 and the fourth capacitor C4, and pin 2 of the sixth operational amplifier OP6 is connected to the seventeenth resistor. One end of R17 is connected to the other fixed end and movable end of the second variable resistor RP2, the other end of the seventeenth resistor R17 is grounded, and the other end of the fourth capacitor C4 is connected to pin 2 of the seventh operational amplifier OP7 It is connected with one end of the eighteenth resistor R18, the 6th pin of the seventh operational amplifier OP7 is connected with the other end of the third capacitor C3, a fixed end and a movable end of the third variable resistor RP3 and one end of the twentieth resistor R20 connection, the other fixed end of the third variable resistor RP3 is connected to the other end of the eighteenth resistor R18, the pin 3 of the seventh operational amplifier OP7 is grounded through the nineteenth resistor R19, and the seventh operational amplifier Pin 6 of OP7 is also connected to pin CH0 of the analog-to-digital converter A/D, the other end of the twentieth resistor R20 is connected to pin 3 of the eighth operational amplifier OP8, and pin 2 of the eighth operational amplifier OP8 passes through The twenty-first resistor R21 is grounded, the 6th pin of the eighth operational amplifier OP8 is connected to the 2nd pin of the ninth operational amplifier OP9 through the 22nd resistor R22, and the 3rd pin of the ninth operational amplifier OP9 is connected to the twentieth Three resistors R23 are grounded, pin 1 of the ninth operational amplifier OP9 is grounded, pin 4 of the ninth operational amplifier OP9 is connected to the -5V power supply of the switching power supply UR in the input signal circuit, and pin 5 of the ninth operational amplifier OP9 , 6 and 8 pins are connected through the twenty-fourth resistor R24 to connect with the 7th pin of the ninth operational amplifier OP9 to form the output terminal of the voltage signal fu, and the 5th, 6th and 8th pins of the ninth operational amplifier OP9 are also connected with the input signal circuit. The +5V power connection of the medium switching power supply UR.

As shown in Figure 4, the voltage and current signal phase measurement circuit is composed of a NAND gate logic chip U, a counter HM, a microprocessor MCU, a crystal oscillator XTAL, 5 capacitors C5 to C9 and a resistor R25. The NAND gate logic Pins 1 and 2 of the chip U are connected to the voltage signal fu output end of the voltage signal analog-to-digital conversion circuit, and the 5th pin of the NAND logic chip U is connected to the current signal fi output end of the current signal analog-to-digital conversion circuit, so The 11-pin of the NAND gate logic chip U is connected with the 10-pin of the counter HM, the 13-pin of the NAND gate logic chip U is connected with the 15-pin of the microprocessor MCU, and the 11-pin of the counter HM is connected with the microprocessor. The 14 pins of the MCU are connected, the 9, 7, 6, 5, 3, 2, 4, and 13 pins of the counter HM are respectively connected to the 1-8 pins of the microprocessor MCU, and the 16 pins of the counter HM are connected to the input signal In the circuit, the 5V power supply of the switching power supply UR is connected, the 8-pin of the counter HM is grounded, one end of the crystal oscillator XTAL is connected to the 19-pin of the microprocessor MCU and one end of the ninth capacitor C9, and the other end of the crystal oscillator XTAL is connected to the microcomputer. Pin 18 of the processor MCU is connected to one end of the eighth capacitor C8, the other end of the eighth capacitor C8 and the other end of the ninth capacitor C9 are grounded, and the WR and RD pins of the microprocessor MCU are connected to the input end of the LCD screen connection, the 13-pin of the microprocessor MCU is connected with the current signal fi output end of the current signal analog-to-digital conversion circuit, and the 12-pin of the microprocessor MCU is connected with the voltage signal fu output end of the voltage signal analog-digital conversion circuit, Pin 9 of the microprocessor MCU is connected with one end of the twenty-fifth resistor R25 and one end of the seventh capacitor C7, and pin 40 of the microprocessor MCU is connected with one end of the fifth capacitor C5, one end of the sixth C6 and The VCC power supply is connected, the 20th pin of the microprocessor MCU is connected to the other end of the fifth capacitor C5 and the other end of the sixth C6 and then grounded, the other end of the seventh capacitor C7 is connected to the VCC power supply, the second The other end of the fifteenth resistor R25 is grounded.

The model of the microprocessor MCU is W78E516, the model of the first to ninth operational amplifiers OP1 to OP9 is OP27, the model of the counter HM is MC4040, and the model of the NAND gate logic chip U is 74LS00. The LCD screen is a touch display with a self-contained system that can be programmed to issue commands, and various miswired phasor diagram databases are preset inside for comparison and judgment with the actually measured phasor diagrams. The model of the analog-to-digital converter A/D is MX197.

The working process of the present invention is:

As shown in Figure 1, the switching power supply UR directly takes power from the secondary voltage circuit of the test grid through the power input transformer B1 and then converts it into direct current to supply the current signal analog-to-digital conversion circuit, the voltage signal analog-to-digital conversion circuit, and the voltage and current signal phase measurement. Circuit and display screen; the power input transformer B1 is 100T/200T, 10VA; the voltage loop transformers B2, B3 and B4 connect the A-phase aerial plug L1, B-phase aerial plug L2, and C-phase aerial plug L3 The connected three-phase power supply is converted into the voltage signal u of the three-phase secondary circuit, and the current circuit isolation transformers B5, B6 and B7 connect the three-phase A-phase aerial plug L1, B-phase aerial plug L2, and C-phase aerial plug L3. The phase power is converted into the current signal i of the three-phase secondary circuit, and the voltage signal u and the current signal i are controlled and transmitted to the current signal analog-to-digital conversion circuit and The voltage signal analog-to-digital conversion circuit; the current signal i also passes through the voltage limiting circuit of the current loop composed of diodes D1 and D2 to limit the voltage below 0.7V; the current signal i is 0.1mA～6A; the voltage signal u is 0.1 mV～2V.

As shown in FIGS. 2 to 3 , when the current signal i is at the no-load mA level, the current signal i first-stage amplifying circuit 1 and the current signal i second-stage amplifying circuit 2 have two stages of 1 to 1,000,000 times. Control high-fidelity amplification, and then pass the Q=3 band-pass filter 3 to obtain a pure sine wave signal, and then convert it into a current square wave signal fi through an AC-to-TTL square wave circuit 4 and send it to the voltage and current signal phase measurement circuit. The voltage signal u is subjected to impedance transformation through the first-stage amplifier circuit 5 of the voltage signal u, and then through the Q=3 band-pass filter 6 to obtain a pure sine wave signal, which is then transformed into a voltage square wave through the AC-to-TTL square wave circuit 7. The signal fu is sent to the phase measurement circuit all the way, and the other way is sent to the analog-to-digital converter A/D to measure the voltage value.

的宽度值，与非门逻辑芯片U的13脚由微处理器MCU的15脚送入f＝18kHz、T＝55.56mS的脉冲信号(1个脉冲等于1°相位角标准计量脉冲)，相与后送给计数器HM，在微处理器MCU控制下实现电压信号u和电流信号i的相位角

在0～±180°范围内直接测量。As shown in Figure 4, the current square wave signal fi and the voltage square wave signal fu are sent to the NAND gate logic chip U of the voltage and current signal phase measurement circuit for logical combination, and are generated at pin 12 of the NAND gate logic chip U. represents the phase of the voltage signal u and the current signal i

The width value of the NAND gate logic chip U is fed into the pulse signal of f=18kHz, T=55.56mS from the 15th pin of the microprocessor MCU (one pulse is equal to 1° phase angle standard metering pulse), and the Then send it to the counter HM, and realize the phase angle of the voltage signal u and the current signal i under the control of the microprocessor MCU

Direct measurement within the range of 0 to ±180°.

The above are only the embodiments of the present invention, and are not intended to limit the scope of the present invention. Any equivalent structure or equivalent process transformation made by using the contents of the description of the present invention, or directly or indirectly applied in other related technical fields, are the same. Included in the scope of patent protection of the present invention.

Claims (5)

1. The utility model provides a no-load on-line inspection tester of three-phase secondary circuit which characterized in that: the LCD liquid crystal display device is characterized by comprising an input signal circuit, a current signal analog-to-digital conversion circuit, a voltage current signal phase measurement circuit and an LCD liquid crystal display, wherein a current signal output end of the input signal circuit is connected with an input end of the current signal analog-to-digital conversion circuit, a voltage signal output end of the input signal circuit is connected with an input end of the voltage signal analog-to-digital conversion circuit, an output end of the current signal analog-to-digital conversion circuit is connected with a current signal input end of the voltage current signal phase measurement circuit, an output end of the voltage signal analog-to-digital conversion circuit is connected with a voltage signal input end of the voltage current signal phase measurement circuit, and a display signal output end of.

2. The no-load on-line inspection tester for the three-phase secondary circuit according to claim 1, characterized in that: the input signal circuit consists of an A-phase aviation plug L1, a B-phase aviation plug L2, a C-phase aviation plug L3, a power input transformer B1, a switching power source UR, a power switch K, three voltage loop transformation transformers B2, B3 and B4, three current loop isolation transformers B5, B6 and B7, a three-phase secondary voltage conversion relay J1, three voltage current loop relays J2, J3 and J4, two diodes D1 and D2, pins 1 and 2 of the A-phase aviation plug L1 are connected with the primary side of the power input transformer B1 and the primary side of a first voltage loop transformation transformer B2, pins 3 and 4 of the A-phase aviation plug L1 are connected with the primary side of a first current loop isolation transformer B5, pins 1 and 2 of the B-phase aviation plug L2 are connected with the primary side of a second voltage loop transformation transformer B3, and pins 3 and 4 of the B-phase aviation plug L2 are connected with the primary side of a second voltage loop isolation transformer B6, pins 1 and 2 of the C-phase air plug L3 are connected with the primary of a third voltage loop transformation transformer B4, pins 3 and 4 of the C-phase air plug L3 are connected with the primary of a third current loop isolation transformer B7, the secondary of the power input transformer B1 is connected with the input end of a switching power source UR, the power switch K is arranged on a line between the secondary of the power input transformer B1 and the input end of the switching power source UR, one end of the secondary of the three voltage loop transformation transformers B2, B3 and B4 is connected with the normally closed contact of a three-phase secondary voltage transformation relay J1, the movable contact of the three-phase secondary voltage transformation relay J1 is connected with one normally open contact of three voltage current loop relays J2, J3 and J4, the middle end of the secondary of the three voltage loop transformation relays B2, B3 and B4 is connected with the normally open contact of the three-phase secondary voltage transformation relay J1, the other ends of the secondary sides of the three voltage loop transformer converters B2, B3 and B4 are grounded, the secondary terminals of the three current loop isolation transformers B5, B6 and B7 are connected with the other normally open contact of the three voltage current loop relays J2, J3 and J4, the other ends of the secondary sides of the three current loop isolation transformers B5, B6 and B7 are grounded, one movable contact of the three voltage current loop relays J2, J3 and J4 is connected to form a voltage signal output end u, the other movable contact of the three voltage-current loop relays J2, J3 and J4 is connected to form a current signal output terminal i, the anode of the first diode D1 is connected with the cathode of the second diode D2 and then connected with the current signal output terminal i, and the cathode of the first diode D1 is connected with the anode of the second diode D2 and then grounded to form a voltage limiting loop of the current loop.

3. The no-load on-line inspection tester for the three-phase secondary circuit according to claim 1, characterized in that: the current signal analog-digital conversion circuit comprises 15 resistors R1 to R15, a first variable resistor RP1, 5 operational amplifiers OP1 to OP5 and two capacitors C1 and C2, one end of the first resistor R1 is connected with the current signal output end i of the input signal circuit, the other end of the first resistor R1 is connected with the 3-pin of the first operational amplifier OP1, the 6-pin of the first operational amplifier OP1 is connected with one end of the second resistor R2 and one end of the fourth resistor R4, the 2-pin of the first operational amplifier OP1 is connected with the other end of the second resistor R2 and one end of the third resistor R3, the other end of the third resistor R9 is grounded, the other end of the fourth resistor R4 is connected with the 3-pin of the second operational amplifier OP2, the 6-pin of the second operational amplifier OP2 is connected with one end of the fifth resistor R5 and one end of the seventh resistor R6 7, and the other end of the second operational amplifier OP 847 is connected with the first resistor R87458 and the sixth resistor R2, the other end of the sixth resistor R6 is grounded, the other end of the seventh resistor R7 is connected to one end of an eighth resistor R8, one end of a first capacitor C1 and one end of a second capacitor C2, the other end of the second capacitor C2 is connected to the pin 2 of a third operational amplifier OP3 and one end of a ninth resistor R9, the pin 6 of the third operational amplifier OP3 is connected to the other end of a first capacitor C1, one fixed end and one movable end of a first variable resistor RP1 and one end of an eleventh resistor R11, the other fixed end of the first variable resistor RP1 is connected to the other end of a ninth resistor R9, the pin 3 of the third operational amplifier OP3 is grounded through a tenth resistor R10, the other end of the eighth resistor R8 is grounded, the other end of the eleventh resistor R11 is connected to the pin 3 of a fourth operational amplifier OP4, the pin 2 of the fourth operational amplifier 4 is grounded through a twelfth resistor R12, the pin 6 of the fourth operational amplifier OP4 is connected to the pin 2 of the fifth operational amplifier OP5 through a thirteenth resistor R13, the pin 3 of the fifth operational amplifier OP5 is connected to the ground through a fourteenth resistor R14, the pin 1 of the fifth operational amplifier OP5 is connected to the ground, the pin 4 of the fifth operational amplifier OP5 is connected to the-5V power supply of the switching power UR in the input signal circuit, the pins 5, 6 and 8 of the fifth operational amplifier OP5 are connected to the pin 7 of the fifth operational amplifier OP5 through a fifteenth resistor R15 after being connected to form a current signal fi output terminal, and the pins 5, 6 and 8 of the fifth operational amplifier OP5 are further connected to the +5V power supply of the switching power UR in the input signal circuit.

4. The no-load on-line inspection tester for the three-phase secondary circuit according to claim 1, characterized in that: the voltage signal analog-digital conversion circuit consists of 9 resistors R16 to R24, second and third variable resistors RP2, RP3, 4 operational amplifiers OP6 to OP9, two capacitors C3, C4 and an analog-digital converter A/D, one end of the sixteenth resistor R16 is connected with a voltage signal output end u of the input signal circuit, the other end of the sixteenth resistor R6 is connected with a pin 3 of a sixth operational amplifier OP6, a pin 6 of the sixth operational amplifier OP6 is connected with a fixed end of the second variable resistor RP2 and one ends of the third capacitor C3 and the fourth capacitor C4, a pin 2 of the sixth operational amplifier OP6 is connected with one end of a seventeenth resistor R17 and the other fixed end and movable end of the second variable resistor RP2, the other end of the seventeenth resistor R17 is grounded, the other end of the fourth capacitor C4 is connected with a pin 2 of the seventh operational amplifier OP7 and an eighteenth resistor R18, a pin 6 of the seventh operational amplifier OP7 is connected to the other end of the third capacitor C3, a fixed end and an active end of the third variable resistor RP3, and one end of the twentieth resistor R20, another fixed end of the third variable resistor RP3 is connected to the other end of the eighteenth resistor R18, a pin 3 of the seventh operational amplifier OP7 is grounded through a nineteenth resistor R19, a pin 6 of the seventh operational amplifier OP7 is further connected to a pin CH0 of the analog-to-digital converter a/D, another end of the twentieth resistor R20 is connected to a pin 3 of the eighth operational amplifier OP8, a pin 2 of the eighth operational amplifier OP8 is grounded through a twenty-first resistor R21, a pin 6 of the eighth operational amplifier 63op 92 is connected to a pin 2 of the ninth operational amplifier 9 through a second twelfth resistor R8, a pin 3 of the eighth operational amplifier OP9 is grounded through a second thirteenth resistor R23, and a pin 361 of the ninth operational amplifier is grounded, the pins 4 of the ninth operational amplifier OP9 are connected with the power supply of-5V of the switching power supply UR in the input signal circuit, the pins 5, 6 and 8 of the ninth operational amplifier OP9 are connected with the pin 7 of the ninth operational amplifier OP9 through the twenty-fourth resistor R24 to form the output end of the voltage signal fu, and the pins 5, 6 and 8 of the ninth operational amplifier OP9 are also connected with the power supply of +5V of the switching power supply UR in the input signal circuit.

5. The no-load on-line inspection tester for the three-phase secondary circuit according to claim 1, characterized in that: the voltage and current signal phase measuring circuit consists of a NAND gate logic chip U, a counter HM, a microprocessor MCU, a crystal oscillator XTAL, 5 capacitors C5-C9 and a resistor R25, wherein pins 1 and 2 of the NAND gate logic chip U are connected with the voltage signal fu output end of a voltage signal analog-to-digital conversion circuit, pin 5 of the NAND gate logic chip U is connected with the current signal fi output end of the current signal analog-to-digital conversion circuit, pin 11 of the NAND gate logic chip U is connected with pin 10 of the counter HM, pin 13 of the NAND gate logic chip U is connected with pin 15 of the microprocessor MCU, pin 11 of the counter HM is connected with pin 14 of the microprocessor MCU, pins 9, 7, 6, 5, 3, 2, 4 and 13 of the counter HM are respectively connected with pins 1-8 of the microprocessor MCU, pin 16 of the counter HM is connected with a 5V power supply of a switching power supply UR in an input signal circuit, the 8 pin of the counter HM is grounded, one end of the crystal oscillator XTAL is connected with one end of a 19 pin and a ninth capacitor C9 of the microprocessor MCU, the other end of the crystal oscillator XTAL is connected with one end of a 18 pin and an eighth capacitor C8 of the microprocessor MCU, the other end of the eighth capacitor C8 and the other end of the ninth capacitor C9 are grounded, WR and RD pins of the microprocessor MCU are connected with the input end of the LCD, a 13 pin of the microprocessor MCU is connected with the current signal fi output end of the current signal analog-to-digital conversion circuit, a 12 pin of the microprocessor MCU is connected with the voltage signal fu output end of the voltage signal analog-to-digital conversion circuit, a 9 pin of the microprocessor MCU is connected with one end of a twenty-fifth resistor R25 and one end of a seventh capacitor C7, a 40 pin of the microprocessor MCU is connected with one end of a fifth capacitor C5, one end of a sixth C6 is connected with a VCC power supply, a 20 pin of the microprocessor MCU is connected with the other end of a fifth capacitor C5 and the other end of, the other end of the seventh capacitor C7 is connected with a VCC power supply, and the other end of the twenty-fifth resistor R25 is grounded.

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