CN105549639A - Pressure vessel auxiliary equipment control method based on PLC control - Google Patents

Abstract

The invention relates to the field of electric power technology, in particular to a method for controlling auxiliary equipment of a pressure vessel based on PLC control. Specifically, a new type of electronic pressure sensor is added to the measuring element of the pressure vessel, and the current analog measurement value is checked online with the debugging computer and PLC, and the digital signal is converted according to the calculation formula P=L*(Px-4000)/(20000-4000) Convert to the actual measured value, adjust the calibration button of pressure sensor A to make the measured pressure value close to the actual pressure value, until the error is eliminated or within the allowable range, add conversion control logic in the program according to the equipment pressure setting value requirements, compile the program and After downloading and applying the new program, conduct an online test, and exit after confirming that it is correct. The invention has high stability, is easy to implement, and is convenient to operate, effectively improves the sensitivity and accuracy of controlling pressure and the control ability of auxiliary equipment, and is more reliable and safe in operation, reducing the harm to people and equipment.

Description

A method of controlling auxiliary equipment of pressure vessel based on PLC control

technical field

The invention relates to the field of electric power technology, in particular to a method for controlling auxiliary equipment of a pressure vessel based on PLC control. It is used for centralized control by PLC, no-load and load switching of high-pressure oil and gas tank auxiliary equipment; start-stop control of pressurized water gas tank inflating and air-supplement auxiliary equipment; and start-stop or change of other pressure-controlled auxiliary equipment for pressure vessels Wait.

Background technique

At present, in the control method of using the pressure value to control the auxiliary equipment of the pressure vessel, a mechanical pressure switch is usually used as the pressure monitoring signal. When the pressure meets the set value of the pressure switch, the upper and lower contacts of the pressure switch will conduct the circuit after touching The signal is sent to the control PLC to control the start-stop or change of the corresponding auxiliary equipment.

This control method is relatively simple, relying on pure mechanical contact to complete the control of the equipment, there are many hidden dangers and the control ability is poor, especially for equipment with long running time and frequent pressure fluctuations, this control method cannot guarantee the pressure. Accuracy, a serious threat to personal and equipment safety. The common problems of this control method using mechanical pressure switches mainly include the following points:

1. Due to long-term frequent use of mechanical pressure switches, the set value will drift, which will affect the accuracy of the pressure.

2. Due to the influence of the surrounding environment, the mechanical contacts cannot be reliably contacted, which affects the reliability of equipment operation.

3. Due to its own structural defects, the mechanical pressure switch leads to the jamming of the contacts, which seriously affects the safety of people and equipment.

This control method using a mechanical pressure switch as the pressure monitoring signal has a simple structure and poor reliability. With the passage of operating time and the influence of the surrounding environment, it cannot guarantee the accuracy of the pressure, and may even endanger the safety of people and equipment. .

Contents of the invention

In order to overcome the above-mentioned defects in the prior art, the present invention provides a method for controlling the auxiliary equipment of the pressure vessel based on PLC control. Its purpose is to prevent the occurrence of the above situation, and provide a new type of electronic pressure sensor as the pressure measurement signal, and add the comparison logic between the measured value and the set value in the PLC program, and the logic output result is the same as that of the mechanical pressure switch. The signal forms a compound logic control, the electronic pressure sensor can effectively improve the accuracy of pressure control, and the dual logic control can effectively ensure the reliability of equipment operation and reduce the harm to people and equipment.

In order to achieve the above object, the technical scheme adopted in the present invention is:

A method for controlling auxiliary equipment of a pressure vessel based on PLC control, the specific operation steps are as follows:

Add a new type of electronic pressure sensor to the measuring element of the pressure vessel. The positive (+) power supply of sensor A is connected to the +24V terminal of PLC analog module B, and the negative (-) power supply of sensor A is connected to the terminal of PLC analog module B. S(+) terminal, the S(-) terminal of PLC analog module B is shorted with the 0V terminal of PLC analog module B; use the debugging computer and PLC to check the current analog measurement value online, according to the calculation formula P=L *(Px-4000)/(20000-4000) Convert the digital signal to the actual measured value, adjust the calibration button of the pressure sensor A, so that the measured pressure value is close to the actual pressure value, until the error is eliminated or within the allowable range, in the program According to the requirements of the equipment pressure setting value, add the conversion control logic, compile the program and download it, conduct an online test after the new program is applied, and exit after confirming that it is correct.

The specific operation steps described are as follows:

(1) Preparation tools:

One output 4-20mA electronic pressure sensor, two adjustable wrenches with a caliber of 30mm, one multi-function multimeter, one flat-head long-stem screwdriver, one cross-stem long-stem screwdriver, and several cable ties;

(2) Installation:

Remove the bolts on the base of the electronic pressure sensor, select an installation position with a suitable aperture on the bracket, insert the electronic pressure sensor with the base downward, reinstall the bolts, and fix the sensor; use a multimeter to measure the positive and negative voltages of the PLC analog input module , confirm that it is 24V, connect the positive (+) of the sensor A power supply to the +24V terminal of the PLC analog module B, connect the negative (-) of the sensor A power supply to the S (+) terminal of the PLC analog module B, and the PLC analog The S(-) terminal of the measurement module B is short-circuited with the 0V terminal of the PLC analog module B;

(3) Calculation formula for converting analog measured value to actual value:

The output of the sensor is 4-20mA current-type analog quantity. There is an A/D converter inside the PLC module, which can convert the analog quantity into a digital quantity of 4000-20000. The actual pressure value can be obtained by using the following conversion formula:

P=L*(Px-4000)/(20000-4000)(1-1);

The parameters are described as follows:

P: measured pressure value after conversion;

L: sensor measurement range;

Px: digital output of analog output via A/D converter;

4000: The digital quantity corresponding to the analog quantity lower limit 4mA;

20000: The digital quantity corresponding to the analog quantity high limit 20mA;

The actual value of the pressure can be calculated according to the above formula. In addition, if the analog quantity exceeds the limit of 4-20mA, or the digital quantity exceeds the limit of 4000-20000, there will be a numerical display, but it has no practical significance;

(4) Accuracy correction:

View the current digital measurement value Px in the PLC module, and use the formula (1-1) to calculate, compare the calculated pressure value with the actual pressure, calculate the error, adjust the fine-tuning button of the sensor, so that the measured pressure value is closer to the actual pressure value Close until the error is eliminated or within the allowable range;

(5) Logic modification:

Introduce the numerical comparison module in the PLC control program, and make the following modifications:

Module GE: greater than or equal to logic, when the value of port A is greater than or equal to the value of port C, Q is turned on to the right;

OK: Module enable terminal, the module works after the left terminal is turned on;

P: measured pressure value calculated by conversion formula (1-1);

X: pressure setting value;

I001: mechanical pressure switch signal;

Q001[S]: Control the start-stop or change of auxiliary equipment;

Comparing the pressure measurement value with the set value, the output result and the pressure switch signal act together to control the start-stop or conversion of the equipment, and the combination of the two control methods forms a composite control;

(6) Compile, download and debug:

Connect the software to the PLC, compile the modified program, download it to the PLC after the compilation is successful, restart the PLC to apply the new program, debug online, and exit after confirming that there is no abnormality.

Advantage of the present invention and application effect are:

The present invention uses a new type of electronic pressure sensor as the pressure measurement signal, and adds the comparison logic between the measured value and the set value in the PLC program. The logic output result and the mechanical pressure switch signal form a composite logic control, and the electronic pressure sensor outputs analog After the amount is converted by the A/D module, the sensitivity and accuracy of the control pressure can be effectively improved. Combined with the mechanical pressure switch to form a composite control logic, the dual logic control can greatly improve the control ability of auxiliary equipment, effectively ensure that the operation of the pressure vessel is more reliable and safe, and reduce the harm to people and equipment.

The control mode of the present invention has high stability, is based on PLC centralized control, is easy to implement, and is convenient to operate. For modern industry, it is easy to be extended to the field of controlling flow, temperature, liquid level and other auxiliary equipment, and has strong applicability.

The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Description of drawings

Fig. 1 is a schematic diagram of the system of the present invention;

Fig. 2 is a hardware structural diagram of the present invention;

Fig. 3 is a logical modification diagram of the present invention;

Fig. 4 is a block diagram of the implementation steps of the present invention.

detailed description

The invention is a method for controlling auxiliary equipment of a pressure vessel based on PLC control. As shown in Figure 1-Figure 4, a new type of electronic pressure sensor is added to the measuring element of the pressure vessel, the power supply of sensor A is positive (+) connected to the +24V terminal of PLC analog module B, and the power supply of sensor A is negative (-) Connect to the S(+) terminal of PLC analog module B, and short-circuit the S(-) terminal of PLC analog module B with the 0V terminal of PLC analog module B; use the debugging computer to connect with the PLC to view the current analog Measured value, according to the calculation formula (1-1), convert the digital signal to the actual measured value, adjust the calibration button of the pressure sensor A, so that the measured pressure value is close to the actual pressure value, until the error is eliminated or within the allowable range, in the program Add conversion control logic according to the equipment pressure setting value requirements, compile the program and download it, conduct an online test after the new program is applied, and exit after confirming that it is correct. The output result of the analog quantity and the mechanical pressure switch work together to control the auxiliary equipment, forming a composite control logic with good reliability and high precision. At the same time, the set value of the analog quantity can be modified at any time according to the need, and the operation is simpler and more convenient.

When the present invention is concretely implemented, the operation process is as follows:

(1) Preparation tools:

One output 4-20mA electronic pressure sensor, two adjustable wrenches with a caliber of 30mm, one multi-function multimeter, one flat-blade long-bar screwdriver, one cross-bar long-bar screwdriver, and several cable ties.

(2) Installation:

Remove the bolts on the base of the electronic pressure sensor, select an installation position with a suitable hole diameter on the bracket, insert the electronic pressure sensor into the base, and reinstall the bolts to fix the sensor. Use a multimeter to measure the positive and negative voltages of the PLC analog input module, confirm that it is 24V, connect the positive (+) of the sensor A power supply to the +24V terminal of the PLC analog module B, and connect the negative (-) of the sensor A power supply to the PLC analog The S(+) terminal of the measurement module B, the S(-) terminal of the PLC analog module B and the 0V terminal of the PLC analog module B are short-circuited.

(3) Calculation formula for converting analog measured value to actual value:

The output of the sensor is 4-20mA current-type analog quantity. There is an A/D converter inside the PLC module, which can convert the analog quantity into a digital quantity of 4000-20000. The actual pressure value can be obtained by using the following conversion formula:

P=L*(Px-4000)/(20000-4000)(1-1);

The parameters are described as follows:

P: measured pressure value after conversion;

L: sensor measurement range;

Px: digital output of analog output via A/D converter;

4000: The digital quantity corresponding to the analog quantity lower limit 4mA;

20000: The digital quantity corresponding to the high limit of 20mA of the analog quantity.

The actual value of the pressure can be calculated according to the above formula. In addition, if the analog quantity exceeds the limit of 4-20mA, or the digital quantity exceeds the limit of 4000-20000, there will be a numerical display, but it has no practical significance.

(4) Accuracy correction:

View the current digital measurement value Px in the PLC module, and use the formula (1-1) to calculate, compare the calculated pressure value with the actual pressure, calculate the error, adjust the fine-tuning button of the sensor, so that the measured pressure value is closer to the actual pressure value Close until the error is eliminated or within the allowable range.

(5) Logic modification:

Introduce the value comparison module in the PLC control program, and make the modification as shown in Figure 1.

As shown in Figure 1, the parameters are described as follows:

Module GE: greater than or equal to logic, when the value of port A is greater than or equal to the value of port C, Q is turned on to the right (the corresponding logic module can be selected according to actual control needs).

OK: Module enable terminal, the module works after the left terminal is turned on;

P: measured pressure value calculated by conversion formula (1-1);

X: pressure setting value;

I001: mechanical pressure switch signal;

Q001[S]: Control the start-stop or change of auxiliary equipment.

Comparing the pressure measurement value with the set value, the output result and the pressure switch signal act together to control the start-stop or conversion of the equipment. The combination of the two control methods forms a compound control, which not only improves the measurement accuracy but also ensures the reliability of the equipment operation. sex.

(6) Compile, download and debug:

Connect the software to the PLC, compile the modified program, download it to the PLC after the compilation is successful, restart the PLC to apply the new program, debug online, and exit after confirming that there is no abnormality.

Claims (2)

1. the method that the pressure vessel utility appliance controlled based on PLC controls, is characterized in that: concrete operation step is as follows:

New-style electronic pressure transducer is increased in the measuring sensor of pressure vessel, sensors A power supply just (+) accesses+24V terminal of PLC analog quantity module B, S (+) terminal of sensors A power supply negative (-) access PLC analog quantity module B, S (-) terminal of PLC analog quantity module B and the 0V terminal short circuit of PLC analog quantity module B; Use debugging computer and PLC is online checks present day analog measuring value, according to computing formula P=L*(Px-4000)/digital signal is scaled actual measured value by (20000-4000), the correcting button of adjustment pressure transducer A, make measured pressure value close to actual pressure value, until error concealment or in allowed band, require to add conversion steering logic according to equipment setting value of pressure in a program, program compiler is also downloaded, carry out on-line testing after new procedures application, confirm errorless backed off after random.

2. a kind of method controlled based on the pressure vessel utility appliance of PLC control according to claim 1, is characterized in that: described concrete operation step is as follows:

(1) preparation tool:

Export 4-20mA electronic pressure transmitter one, the monkey wrench of bore 30mm two, multi-function multimeter one, one, a word length bar screwdriver, one, cross stock screwdriver, band is some;

(2) install:

Pulled down by bolt on electronic pressure transmitter base, support is chosen the installation site that aperture is suitable, and base inserts electronic pressure transmitter downwards, and bolt is returned dress, fixation of sensor; The both positive and negative polarity voltage of PLC Analog input mModule is measured with multimeter, confirm as 24V, by+24V the terminal of sensors A power supply just (+) access PLC analog quantity module B, S (+) terminal of sensors A power supply negative (-) access PLC analog quantity module B, S (-) terminal of PLC analog quantity module B and the 0V terminal short circuit of PLC analog quantity module B;

(3) analog quantity measured value conversion calculated with actual values formula:

Sensor exports as 4-20mA current mode analog quantity, and PLC module inside is provided with A/D converter, this analog quantity can be converted to the digital quantity of 4000-20000, utilizes following conversion formula can draw actual force value:

P=L*（Px-4000）/（20000-4000）（1-1）；

Parameter is described below:

P: the measured pressure value after conversion;

L: sensor measurement range;

Px: the digital quantity that analog quantity exports through A/D converter;

4000: the digital quantity that analog quantity lower bound 4mA is corresponding;

20000: the digital quantity that analog quantity high limit 20mA is corresponding;

Can calculate the actual value of pressure according to above-mentioned formula, if analog quantity crosses the restriction of 4-20mA in addition, or digital quantity crosses the restriction of 4000-20000, has numerical value display, but does not have practical significance;

(4) accuracy correction:

Check Contemporary Digital measuring value Px in PLC module, and utilize formula (1-1) to calculate, the force value calculated and actual pressure are compared, calculate error, the trim button of adjustment sensor, makes measured pressure value close to actual pressure value, until error concealment or in allowed band;

(5) logic Modification:

In PLC control program, introduce numerical value comparison module, and do following amendment:

When module GE: be more than or equal to logic, A port value is more than or equal to C port value, make Q conducting to the right;

OK: module Enable Pin, module work after left end conducting;

P: the pressure measured value calculated through conversion formula (1-1);

X: pressure set points;

I001: mechanical pressure switch signal;

Q001 [S]: control utility appliance start and stop or conversion;

Pressure measured value and setting value are compared, Output rusults and the acting in conjunction of pressure switch signal are in the start and stop of opertaing device or conversion, and two kinds of control modes combine formation complex controll;

(6) debugging is downloaded in compiling:

By software and PLC online, the program revised is compiled, compiles successfully and be downloaded to PLC, restart PLC and apply new program, debug online, confirm backed off after random without exception.