CN108181538B

CN108181538B - Intelligent short circuit experiment table

Info

Publication number: CN108181538B
Application number: CN201810207684.0A
Authority: CN
Inventors: 顾涛; 赵永华; 张国瑞; 安源; 王秋波; 张博
Original assignee: North China Institute of Science and Technology
Current assignee: North China Institute of Science and Technology
Priority date: 2018-03-14
Filing date: 2018-03-14
Publication date: 2021-01-05
Anticipated expiration: 2038-03-14
Also published as: CN108181538A

Abstract

The invention relates to an intelligent short-circuit experiment table for simulating a short-circuit state of electric field lines and acquiring a current sudden change condition when the electric field lines are short-circuited. The third electronic switch controls the second resistor to be merged into the current simulation loop, and the current mutation condition in the electric field line can be simulated by recording the reading of the ammeter before and after the second resistor is merged into the current simulation loop. The first electronic switch and the second electronic switch are controlled to be disconnected, so that the conditions that the electric field falls to zero and the current in the line is zero can be simulated. The on-off states of the three electronic switches are controlled by the controller in a programming mode, so that the switching time is microsecond, and the short circuit simulation time length can be flexibly controlled. Meanwhile, the resistance switching process in the control circuit is programmed by the controller, so that the current change process under various different conditions on the site can be simulated, and the experiment table has more flexibility and expandability.

Description

Intelligent short circuit experiment table

Technical Field

The invention relates to an intelligent short circuit experiment table.

Background

The power system may have many types of faults, and the following are common faults which are relatively serious in damage to the power system: short circuits, open phases, and various other complex faults. While short circuit faults are the most common faults in power systems. When a short circuit occurs in an electric power system, a fundamental phenomenon accompanying the short circuit is a sharp increase in current.

Because the short-circuit fault is more harmful, the current power supply system is provided with quick-break control equipment aiming at the short-circuit fault. When a short circuit occurs, the system is automatically powered off, and how to verify that the quick-break equipment reaches the design standard, the phenomenon of short-circuit fault occurrence needs to be simulated in a laboratory so as to test the correctness of the quick-break control facility. Therefore, the research and the improvement of the short circuit experimental device have important significance.

Disclosure of Invention

The invention aims to provide an intelligent short-circuit experiment table for simulating a short-circuit state of electric field lines and acquiring a current sudden change condition when the electric field lines are short-circuited.

In order to achieve the purpose, the intelligent short circuit experiment table adopts the following technical scheme:

the intelligent short-circuit experiment table comprises a voltage simulation loop, a current simulation loop, a controller and a PC (personal computer), wherein the voltage simulation loop comprises a transformer and a first electronic switch K1 which are arranged on a ground-to-ground field simulation line in series, the intelligent short-circuit experiment table also comprises a data acquisition terminal which is in conductive connection with the ground-to-ground field simulation line to measure the current and the electric field in the voltage simulation loop, and the controller is connected with the data acquisition terminal through a wireless communication signal to receive the current value and the electric field value acquired by the data acquisition terminal; the current simulation loop comprises a second electronic switch K2, a first resistor, an N-turn coil, an ammeter and a measuring CT (current transformer), wherein the ammeter is used for measuring the current flowing through the single-turn coil, and the second resistor is connected with the first resistor in parallel through a third electronic switch K3; the measuring CT is connected with the controller to convert a current signal flowing through the measuring CT into a digital signal and transmit the digital signal to the controller, the PC is connected with a serial port of the controller to receive and display an analog current value received by the controller, and the first electronic switch K1, the second electronic switch K2 and the third electronic switch K3 are connected with different output pins of the controller to switch the on-off state of the corresponding electronic switches through a program in the controller.

And a clamp ammeter used for measuring the total current of N turns in the N turns of coils is arranged on the N turns of coils.

And the measurement CT and data acquisition terminal is arranged on the N turns of coils.

The controller is STM32F107 in model number and comprises a serial port 1, a serial port 2 and an A/D0 data conversion port, wherein the serial port 1 is connected with a CC1011 module, the serial port 2 is connected with a PC, the CC1011 module is a 433MHZ wireless communication module, and the data acquisition terminal comprises an adaptive module corresponding to the wireless communication module so as to realize the signal connection between the data acquisition terminal and the controller; the controller also comprises an output pin CPU _ PB0, an output pin CPU _ PB1 and an output pin CPU _ PB2, wherein the output pin CPU _ PB0, the output pin CPU _ PB1 and the output pin CPU _ PB2 are correspondingly connected with the first electronic switch K1, the second electronic switch K2 and the third electronic switch K3.

The first electronic switch K1, the second electronic switch K2 and the third electronic switch K3 are all PS710B _ 1A.

The transformer in the voltage simulation loop comprises a single-phase voltage regulator T1 and a single-phase transformer T2 so as to simulate the voltage of a ground electric field simulation line with the working voltage of 10 KV; the current simulation loop includes a single-phase voltage regulator T3 connected in series in the loop.

The invention has the following beneficial effects: the third electronic switch controls the second resistor to be merged into the current simulation loop so as to achieve the effect of switching the size of the resistor in the current simulation loop, and the condition of current mutation in the electric field lines can be simulated by recording the reading of the ammeter before and after the second resistor is merged into the current simulation loop. The first electronic switch and the second electronic switch are controlled to be disconnected, so that the conditions that the electric field falls to zero and the current in the line is zero can be simulated. The on-off states of the three electronic switches are controlled by the controller in a programming mode, so that the switching time is microsecond, and the short circuit simulation time length can be flexibly controlled. Meanwhile, the resistance switching process in the control circuit is programmed by the controller, so that the current change process under various different conditions on the site can be simulated, and the experiment table has more flexibility and expandability.

Drawings

FIG. 1 is a schematic structural diagram of an embodiment of an intelligent short-circuit test bench of the present invention;

FIG. 2 is a diagram of a main program frame of the controller according to the present invention.

Detailed Description

The structural schematic diagram of the intelligent short circuit experiment table is shown in fig. 1, and the intelligent short circuit experiment table comprises a voltage simulation loop, a current simulation loop, a controller and a PC (personal computer). The voltage analog loop and the current analog loop are two isolated loops.

The voltage simulation loop is used for simulating the voltage of electric field lines in a 10KV power supply system, and comprises a single-phase voltage regulator T1, a single-phase transformer T2 and a first electronic switch K1 which are arranged in series in the ground electric field simulation lines, and further comprises a data acquisition terminal for measuring the current in the voltage simulation loop. The single-phase voltage regulator T1 is used to change the civil ac 220V voltage into ac 100V, and the transformation ratio of the single-phase transformer T2 is 1/100 to change the ac 100V voltage into ac 10KV voltage, at this time, the ac voltage of 10KV is simulated in the ground field analog line. The ground electric field analog line is pressed on the data acquisition terminal through the pressure spring, and the current and the electric field which circulate in the data acquisition terminal are the actual circulating current and the electric field in the ground electric field analog line.

The current simulation circuit is used for simulating large current flowing in a 10KV high-voltage electric field line, and comprises a single-phase voltage regulator T3, a second electronic switch K2, a first resistor R1, an N-turn coil, an ammeter A1 and a measuring CT which are connected in series, and further comprises a second resistor R2 connected with the first resistor R1 in parallel, wherein a branch where the second resistor R2 is located is provided with a third electronic switch K3 in series. The second resistor R2 is merged into the short-circuit analog loop when the third electronic switch K3 is closed, and the second resistor R2 is removed from the short-circuit analog loop when the third electronic switch K3 is open. The first resistor R1 and the second resistor R2 both adopt power resistors with variable resistance values. The N turns of coils are formed by N turns of enameled wire loop wires, and the larger total current value of the N turns can be ensured to meet the large current in the 10KV high-voltage electric field line when the circulating current of each turn is extremely small. Therefore, the transformer T3 converts the alternating current 220V voltage into the alternating current 60V voltage, which can meet the power supply requirement of the current analog loop and improve the safety of the current analog loop. The measuring CT is used for measuring the total current on the N turns of coils, and in order to correct the measured value of the current flowing in the measuring CT, a clamp-on ammeter A2 which is used for measuring the total current flowing in the N turns of coils and has extremely high precision is arranged on the N turns of coils. The ammeter a1 is connected in series in the short circuit simulation loop, so its measurement value is the value of the current flowing through the single turn coil.

The measuring CT is arranged on the N turns of coils so that the short-circuit experiment table structure of the invention is more integrated and compact, and the fact that only a mechanical connection relationship exists between the measuring CT and the N turns of coils and a circuit connection relationship does not exist needs to be emphasized.

The specific model of the controller is STM32F107, and the controller comprises an output pin CPU _ PB0, an output pin CPU _ PB1, an output pin CPU _ PB2, a serial port 1, a serial port 2 and an A/D0 data conversion port. Wherein serial port 1 is connected with the CC1011 module, and serial port 2 is connected with the PC. The CC1011 module is a 433MHZ wireless communication module and is used for realizing wireless communication. The PC is used for setting short-circuit time parameters or other time parameters. The A/D0 data conversion port is connected with the CT coil to convert the current on the CT into digital signal, which is transmitted to PC via serial port 2 for storage and display.

The data acquisition terminal is also arranged on the N turns of coils to further improve the integration level of the experiment table structure, and the data acquisition terminal is only mechanically connected with the N turns of coils and is not connected with a circuit. The data acquisition terminal is connected with the CC1011 module through a transmission protocol so as to transmit the acquired current data and the acquired electric field data to the controller through the serial port 1, and the controller transmits the data to the PC through the serial port 2.

The models of the first electronic switch K1, the second electronic switch K2 and the third electronic switch K3 are PS710B _1A, and the three output pins are connected with the three electronic switches in a one-to-one correspondence mode. The resistance of the electronic switch after being turned on is 0.05 ohm, and the electronic switch can be ignored in calculation, and the maximum load current of the switch is 2.5A. When the control interface outputs a high level, the corresponding electronic switch is conducted, and a circuit between the port 4 and the port 6 of the electronic switch is conducted; when the control interface outputs a low level, the corresponding electronic switch is switched off, and the circuit between the port 4 and the port 6 of the electronic switch is switched off.

The procedure for performing the short circuit simulation was as follows:

in the first step, the first electronic switch K1 and the second electronic switch K2 are turned on, and the third electronic switch K3 is turned off, at this time, 10KV voltage exists in the ground electric field analog line, and the line current condition can be simulated in the N-turn coil. The current meter measures the current I U/R1 and the total current of the N-turn coil is approximately equal to NI.

And secondly, adjusting the second resistor R2 to be 1/M of the first resistor R1, turning on the third electronic switch K3 to enable the second resistor R2 to be merged into a short-circuit analog loop, wherein the total resistance of the first resistor R1 and the second resistor R2 is changed into R1/(M +1), the current measured by an ammeter is (M +1) I, and the total current of the analog N-turn coil is approximately equal to N (M +1) I. At this time, the current jump similar to MNI can be simulated.

Thirdly, after delaying for a period of time, the first electronic switch K1 and the second electronic switch K2 are switched off, and the change that the electric field falls to zero and the line current is zero can be simulated.

From the above analysis process, after the number of turns N is fixed, the abrupt change value is only related to M and I, so that the value of the first resistor R1 can be adjusted and changed to adjust the value of I when designing the short-circuit fault simulation. The second resistor R2 is then adjusted to adjust the value of M. Thereby adjusting the short-circuit current value in accordance with the abrupt change value.

For example: if it is determined that the 200-turn bench is used, the amount of the short-circuit current abrupt change is 200A, and the base current in the 200-turn coil is 10A, NMI is 200, and NI is 10A. From this, I-0.05A and M-20 can be derived. Further, when R1 ═ 50 ohms (electric field line equivalent total resistance) is selected, it can be deduced that V2 ═ 2.5V and R2 ═ 2.5 ohms. Thus, before the experiment, the experiment conditions of different combinations of I and M can be obtained, and the parameters are adjusted in advance to be used for the experiment.

Since the short circuit is very damaging to the system, the short circuit analog duration needs to be precisely controlled to prevent large losses from occurring. The on-off states of the three electronic switches are controlled by the controller in a programming mode, so that the switching time is microsecond, and the short circuit simulation time length can be flexibly controlled. Meanwhile, the resistance switching process in the control circuit is programmed by the controller, so that the current change process under various different conditions on the site can be simulated, and the experiment table has more flexibility and expandability.

Meanwhile, the invention separately simulates the current and the voltage of the 10KV electric field line, which is beneficial to ensuring the accuracy of the simulation result and simultaneously improving the safety performance of the short circuit experiment table.

The whole system work control is completed by a PC program and an STM32F107 program. The PC machine completes communication through the serial port 2 and the STM32F 107. The PC active communication protocol format is as follows:

frame header (68H, one byte), length (frame length, 1 byte, 07) type code (01, experiment type code, 01 to 08, one byte), time 1(2 bytes), time 2(2 bytes), time 3(2 bytes), checksum (type to time 3 cumulative sum), frame end (16H, one byte)

After the STM32F107 receives the correct communication frame, the reply frame:

68H01H00H01H16H

and after receiving the message, the PC system interface displays a communication success prompt.

In the above protocol, the meaning of the experimental type code byte is subdivided into:

01 represents a short-circuit fault, 02 represents load fluctuation, 03 represents a no-load closing inrush current of the transformer, 04 represents a line sudden closing load inrush current, 05 represents a manually switched large load, 06 represents a non-fault phase reclosing inrush current, 07 represents a ground fault, and 08 represents a power failure state.

In each experimental case, the STM32F107 samples via the a/D0, records the experimental waveform, and sends it to the PC via the serial port 2 for display.

STM32F107 active transmit data communication protocol format:

header (68H, one byte), type (one byte, 01, CT data, F2, data acquisition terminal data, high order F for data acquisition terminal number, 0-F), length (frame length, 2 bytes, from data start to CRC check code end), data (n bytes), CRC check code (2 bytes), frame end (16H)

After the PC host correctly receives the data frame, replying to the STM32F107 frame:

68H01H00H01H16H and displays the waveform. The host computer calculates and displays the current effective values before and after the fault through the oscillogram, and simultaneously displays the oscillogram of the electric field effective values.

The PC host program also has an edit box setting time 1 to time 3 in milliseconds.

The CC1011 effect of STM32F107 is: after a certain experiment is finished, the data acquisition terminal is communicated, the data sampled by the data acquisition terminal is taken out, the STM32F107 transmits the acquired data to a PC (personal computer) through a serial port 2, the data is compared with the waveform of CT (computed tomography) sampled data, and various data algorithm analysis is carried out next step.

Claims

1. Intelligent short circuit experiment table, its characterized in that: the device comprises a voltage simulation loop, a current simulation loop, a controller and a PC, wherein the voltage simulation loop comprises a transformer and a first electronic switch K1 which are arranged on a ground-to-ground electric field simulation line in series, the device also comprises a data acquisition terminal which is in conductive connection with the ground-to-ground electric field simulation line to measure the current and the electric field in the voltage simulation loop, and the controller is connected with the data acquisition terminal through a wireless communication signal to receive the current value and the electric field value acquired by the data acquisition terminal; the current simulation loop comprises a single-phase voltage regulator, a second electronic switch K2, a first resistor, an N-turn coil, a current meter and a measuring CT (current transformer) for measuring the total current of the N-turn coil, which are connected in series, and also comprises a second resistor connected with the first resistor in parallel, wherein a branch where the second resistor is located is provided with a third electronic switch in series, and the current meter is used for measuring the current flowing through the single-turn coil; the measuring CT is connected with the controller to convert a current signal flowing through the measuring CT into a digital signal and transmit the digital signal to the controller, the PC is connected with a serial port of the controller to receive and display an analog current value received by the controller, and the first electronic switch K1, the second electronic switch K2 and the third electronic switch K3 are connected with different output pins of the controller to switch the on-off state of the corresponding electronic switches through a program in the controller.

2. The intelligent short-circuit experiment table according to claim 1, wherein: and a clamp ammeter used for measuring the total current of N turns in the N turns of coils is arranged on the N turns of coils.

3. The intelligent short-circuit experiment table according to claim 1, wherein: and the measurement CT and data acquisition terminal is arranged on the N turns of coils.

4. The intelligent short-circuit experiment table according to claim 1, wherein: the controller is STM32F107 in model number and comprises a serial port 1, a serial port 2 and an A/D0 data conversion port, wherein the serial port 1 is connected with a CC1011 module, the serial port 2 is connected with a PC, the CC1011 module is a 433MHZ wireless communication module, and the data acquisition terminal comprises an adaptive module corresponding to the wireless communication module so as to realize the signal connection between the data acquisition terminal and the controller; the controller also comprises an output pin CPU _ PB0, an output pin CPU _ PB1 and an output pin CPU _ PB2, wherein the output pin CPU _ PB0, the output pin CPU _ PB1 and the output pin CPU _ PB2 are correspondingly connected with the first electronic switch K1, the second electronic switch K2 and the third electronic switch K3.

5. The intelligent short-circuit experiment table according to claim 4, wherein: the first electronic switch K1, the second electronic switch K2 and the third electronic switch K3 are all PS710B _ 1A.

6. The intelligent short-circuit experiment table according to any one of claims 1-5, wherein: the transformer in the voltage simulation loop comprises a single-phase voltage regulator T1 and a single-phase transformer T2 so as to simulate the voltage of a ground electric field simulation line with the working voltage of 10 KV; the current simulation loop includes a single-phase voltage regulator T3 connected in series in the loop.