Sensing signal transmitting system for liquid caustic soda production

Abstract

The invention discloses a sensing signal transmitting system for liquid caustic soda production, which comprises the steps of acquiring and processing a sensing signal at a production equipment end, coupling the sensing signal with a low-voltage power grid, transmitting the signal by using a high-frequency low-frequency band narrowband communication technology, receiving and processing the sensing signal at a central control end, and inputting the sensing signal into a PC (Personal Computer), various control signals are generated in combination with production process software, and the control signals are coupled and then transmitted to a production equipment end to be processed and executed. A low-voltage power grid high-frequency low-frequency band narrow-band communication technology is adopted, the defects that wiring transmission of sensing and control signals of a traditional liquid caustic soda production line is high and existing carrier communication has high requirements for frequency, frequency band and bandwidth are overcome, and on the basis that stable transmission of the sensing and control signals and normal operation of equipment are met, the communication efficiency is improved. The technical difficulty and cost of the system are reduced, and the problems of technical upgrading and reconstruction of the existing production line and sensing and control signal transmission of a newly-built production line are effectively solved.

Description

Technical Field

[0001] The invention relates to the technical field of salt chemical production equipment control, and specifically discloses a sensor signal transmission system for liquid alkali production. Background Art

[0002] In the salt chemical industry, the liquid caustic soda production line is an important production equipment, and the stability and accuracy of its system operation are crucial to product quality and production efficiency. Accurate transmission and effective control of sensor signals are key factors to ensure the normal operation of the liquid caustic soda production line. With the continuous development of industrial automation, higher requirements are placed on the sensor and control signal transmission system of the liquid caustic soda production line. However, the traditional liquid caustic soda production line mainly uses wiring transmission for sensor and control signals. This method requires laying a large number of signal and control cables between production equipment, which not only increases the construction cost and construction difficulty of the system, but also faces many inconveniences in the later maintenance and upgrading process. For example, when the location of the production equipment changes or new equipment needs to be added, rewiring will cost a lot of time and manpower costs. In addition, wiring transmission is also easily affected by environmental factors, resulting in aging and damage of cables, which may lead to unstable or even interrupted signal transmission, thus affecting the normal operation of the production line.

[0003] The application of existing carrier communication technology in liquid alkali production lines also has some shortcomings. Because the existing carrier communication has high requirements for frequency, frequency band and bandwidth, the technical difficulty and cost of the system increase, and there is also the problem of redundant technical indicators. In practical applications, due to the complex electromagnetic environment of the liquid alkali production line, high-frequency and wide-band carrier communication is more susceptible to external interference, resulting in reduced reliability of signal transmission. In addition, the high requirements for frequency, frequency band and bandwidth also limit the widespread application of carrier communication technology in liquid alkali production lines, and cannot meet the needs of different production scenarios.

[0004] At present, there are relatively few studies on the relevant technologies of sensing and control signal transmission for liquid caustic soda production lines, and a mature, efficient and low-cost transmission and control system has not yet been formed. The existing transmission and control methods cannot meet the needs of refined and intelligent control of liquid caustic soda production lines, and it is difficult to reduce the technical difficulty and cost of the system while ensuring stable signal transmission and normal operation of equipment. Therefore, it is of great practical significance to develop a new type of sensor signal transmission system for liquid caustic soda production. Summary of the invention

[0005] The invention discloses a sensor signal transmission system for liquid caustic soda production, aiming to solve the problems of complex wiring and high carrier communication requirements in the existing liquid caustic soda production line sensor and control signal transmission.

[0006] The technical solution adopted by the present invention to solve the above technical problems is: a sensor signal transmission system for liquid alkali production, comprising the following steps:

[0007] S100: collecting and processing sensor signals from production equipment;

[0008] S200: It uses inductive coupling to couple the sensor signal at the production equipment end with the power line of the low-voltage power grid, and performs high-frequency and low-frequency narrowband transmission;

[0009] S300: At the central control end, high-frequency sensor signals are acquired and processed by capacitive coupling;

[0010] S400: Input the sensor signal into the PC and generate various control signals in combination with the production process software;

[0011] S500: Processing the control signal of the central control end and coupling and transmitting it with the power line of the low-voltage power grid by inductive coupling;

[0012] S600: On the production equipment side, high-frequency sensor signals are obtained and processed by capacitive coupling;

[0013] S700: After the control instructions issued by the central control end are processed as above, they are executed in an orderly manner at the production equipment end.

[0014] Furthermore, in S100, the method for collecting and processing the sensor signal at the production equipment end is as follows:

[0015] S110: According to the production process requirements, for locations where dynamic physical quantity changes need to be measured, such as tank containers, pipelines, and supporting electrical appliances, necessary sensors including pressure, temperature, capacity, mass, flow rate, specific gravity, speed, voltage, and current sensors shall be installed according to the principle of the same or similar raw material properties, the same or similar processes, the same or similar procedures, and the same or similar safety indicators;

[0016] S120: Connecting the above sensor signal to the sensor signal processing module in the signal transmission equipment box at the production equipment end through a multi-core signal cable with double shielding, and performing corresponding operational amplification or attenuation;

[0017] S130: Encoding the sensor signal after the operation amplification or attenuation; wherein, for a common sensor that outputs an analog electrical signal, it is necessary to perform analog-to-digital conversion on the sensor signal after the operation amplification or attenuation, and for a digital sensor or smart sensor that outputs a digital sensor signal, it is possible to directly encode without analog-to-digital conversion;

[0018] S140: Modulate the encoded sensing signal with the local oscillator signal generated by the frequency conversion module, which has a frequency of 200 kHz and a bandwidth of 2 kHz, to generate a narrowband sensing signal in the high-frequency and low-frequency bands;

[0019] S150: After high-frequency amplification of the generated narrowband sensing signal in the high-frequency and low-frequency bands, couple and transmit it through a high-frequency coupling inductance coil to two-phase power lines of the power grid.

[0020] Further, in S150, after the generated narrowband sensing signal in the high-frequency and low-frequency bands is amplified by 1 to 2 stages of high-frequency amplification, it is coupled and transmitted through a high-frequency coupling inductance coil to two-phase power lines of the power grid. The specific content is as follows:

[0021] S210: Set 3 high-frequency reactors at the front end of the secondary of the power transformer. The relevant calculation method is as follows:

[0022] S211: Calculate the core specifications of the reactor according to the usage characteristics of the reactor. The calculation formula is as follows:

[0023] Among them, The effective cross-sectional area of the core (unit: cm²), represents the effective magnetic path length of the core (unit: cm), L represents the target inductance (unit: H), represents the peak power frequency current (unit: A), represents the saturation magnetic flux density of the core (unit: T), represents the permeability of free space (unit: H / m), represents the relative permeability of the core material (unit: H / m), represents the effective power frequency current (unit: A);

[0024] S212: Calculate the number of turns of the high-frequency reactor coil. The calculation formula is as follows:

[0025]

[0026] Among them, represents the number of turns of the high-frequency reactor coil, represents the effective magnetic path length of the core (unit: m), L represents the target inductance (unit: H), represents the permeability of free space (unit: H / m), represents the relative permeability of the core material (unit: H / m), The effective cross-sectional area of the core (unit: cm²);

[0027] S213: Calculate the wire diameter of the reactor through the basic current capacity of the power line. The calculation formula is as follows:

[0028]

[0029] in, Represents the wire diameter (unit: mm), Indicates the effective current of the conductor (unit: A). Indicates the current density (usually 3 to 5 A / mm , high frequency can be reduced to 2~3 A / mm² ;

[0030] S214: In order to meet the dual constraints of the current capacity of the reactor and the high-frequency skin effect, the effective diameter of the conductor at high frequency should be less than 2 times the skin depth. The calculation formula is as follows:

[0031]

[0032] in, Indicates skin depth (unit: mm), Indicates the conductor resistivity (unit: Ω.m), Indicates the operating frequency (unit: Hz), Indicates the magnetic permeability of the conductor (unit: H / m). In actual design and use, the wire diameter is generally required to be: If the calculated result exceeds this value, use multiple strands of Litz wire to reduce the AC resistance.

[0033] S220: At the two input ends of the switching power supply module whose input voltage is 380V phase-to-phase voltage of the signal transmission equipment box at the production equipment end, two circular coupling magnetic rings consisting of four C-shaped semicircular magnetic rings connected and closed in pairs are provided, on which a primary coil and a secondary coil consisting of a power line are provided. The specific contents are as follows:

[0034] S221: The DC power supply of the sensor signal transmitter at the production equipment end is powered by a switching power supply module with an input voltage of 380V phase-to-phase voltage;

[0035] S222: Calculate the high-frequency impedance matching data of the coil to satisfy the high-frequency and low-frequency characteristics of the system. The calculation formula is as follows:

[0036]

[0037] in, Indicates the inductance of the high-frequency coil (unit: H), High frequency carrier circuit characteristic impedance (unit: Ω), Indicates the high-frequency carrier frequency (unit: Hz),

[0038] S223: Obtain the technical parameters of the magnetic core through the technical parameter requirements of the circuit and in combination with the query and calculation of empirical data. The calculation formula is as follows:

[0039]

[0040] Among them, The effective cross-sectional area of the magnetic core (unit: m², commonly cm²), represents the effective magnetic path length of the magnetic core (unit: m), L represents the target inductance (unit: H), represents the power frequency peak current (unit: A), represents the saturation magnetic flux density of the magnetic core (unit: T), represents the permeability of free space (unit: H / m), represents the relative permeability of the magnetic core material (unit: H / m). In the formula, , represents the power frequency effective current (unit: A);

[0041] S224: Calculate the wire diameter of the primary of the high-frequency coupling inductor coil through the effective value of the high-frequency side current and the current density of the signal input. The calculation formula is as follows:

[0042]

[0043] Among them, represents the primary high-frequency side wire diameter, represents the effective value of the high-frequency current (unit: A), represents the high-frequency current density (unit: mm²),

[0044] S225: Calculate the wire diameter of the secondary of the low-frequency coupling inductor coil through the effective value of the low-frequency current and the current density on the power line side of the signal coupling output side, i.e., the power grid side. The calculation formula is as follows:

[0045]

[0046] Among them, represents the secondary low-frequency end wire diameter, represents the effective value of the low-frequency current (unit: A), represents the low-frequency current density (unit: mm², generally taking 3 - 5 A / mm²);

[0047] S226: Calculate the inductance of the coupling coil to calculate the number of turns of the coupling coil. The calculation formula is as follows:

[0048]

[0049] Among them, represents the inductance of the low-frequency coil (unit: H), Represents low frequency voltage (V) Represents the low-frequency carrier frequency (unit: Hz), Represents the effective value of low-frequency current (unit: A);

[0050]

[0051] in, Represents the inductance of the high-frequency coil (unit: H), Represents high frequency voltage (V) Represents the high-frequency carrier frequency (unit: Hz), Represents the effective value of high-frequency current (unit: A);

[0052] S227: Calculate the number of turns of the high-frequency coil to meet the technical requirements for signal transmission. The calculation formula is as follows:

[0053]

[0054] in, Indicates the number of turns of the inductor coil, represents the effective length of the magnetic circuit (unit: m), L represents the design target inductance (unit: H), μ0 represents the vacuum permeability (unit: H / m, generally copper H / m), Relative magnetic permeability (unit: H / m), Represents the effective cross-sectional area of ​​the core (unit: mm²);

[0055] S228: The encoded sensor signals are collected and modulated with the high-frequency signal with a frequency of 200kHz and a bandwidth of 2kHz generated by the production equipment-side signal processing module group in the production equipment-side signal transmission equipment box to generate a high-frequency sensor signal. After 1 to 2 levels of high-frequency amplification, the high-frequency coupled inductor is connected in series with the two input ends of the switching power supply module for in-phase coupling transmission.

[0056] Furthermore, in S300, the central control end uses capacitive coupling to obtain the high-frequency carrier signal and processes it, including the following contents:

[0057] S310: The DC power supply of the sensor signal transmitter at the central control terminal is powered by a switching power supply module with an input voltage of 380V phase-to-phase voltage;

[0058] S320: A high-frequency coupling capacitor is connected to each input end of the two switching power supply modules, and the calculation method of the capacity is as follows:

[0059] S321: Calculate the withstand voltage of the high-frequency coupling capacitor. First, calculate the peak value of its power frequency voltage using the following formula:

[0060]

[0061] Among them, represents the peak voltage (unit: V) represents the power frequency voltage value (unit: V);

[0062] S322: Through theoretical calculation and experiment, the X2 type thin film capacitor is selected here, which is suitable for cross-line interference suppression, and the withstand voltage level is 2.5 kV to 4 kV. Ceramic capacitors have good high-frequency characteristics, but due to their low withstand voltage, they need to be used in series.

[0063] S323: Calculate the capacitance of the high-frequency coupling capacitor, and the calculation formula of its capacitance is as follows:

[0064]

[0065] Among them, represents the capacitance of the coupling capacitor (unit: nF), represents the carrier frequency (unit: Hz), represents the capacitance impedance (unit: Ω), and in actual use, it should satisfy: Among them is the characteristic impedance of the power line, usually 50 Ω to 600 Ω.

[0066] Furthermore, in the S400, the inputting the high-frequency carrier signal into the PC, and generating various control signals through the operation of the production process computer software includes the following content:

[0067] S410: Decode the high-frequency sensing signal obtained through capacitive coupling to obtain high-frequency sensing signals corresponding to different sensors and containing different sensing information;

[0068] S420: Input the high-frequency sensing signals containing different sensing information into the corresponding signal processing modules, and send them to the PC in the central control room through amplification by an operational amplifier and optical coupling isolation;

[0069] S430: The PC in the central control room analyzes and judges various input sensing signals through software, and generates various control signals through operation according to the process and timing requirements of the software.

[0070] Furthermore, in the S500, the

[0071] processing the central control end control signal and coupling and transmitting it with the power line of the low-voltage power grid in an inductive coupling manner includes the following content:

[0072] S510: Encode the generated control signal amplified by the operational amplifier;

[0073] S520: modulate the encoded control signal with a high-frequency signal with a frequency of 200kHz and a bandwidth of 2kHz generated by the central control terminal signal processing module group in the central control terminal signal transmission device box to generate a high-frequency control signal, and after 1-2 levels of high-frequency amplification, connect the high-frequency coupling inductor coil and the two input ends of the switching power supply module powered by the signal transmission device in series and in-phase coupling transmission;

[0074] S530: The design, calculation and manufacturing methods of the high-frequency coupled inductor coil in the above steps are the same as those described in S220.

[0075] Furthermore, in S600, the high-frequency sensor signal is obtained and processed by capacitive coupling at the production equipment end;

[0076] S610: Connect a high-frequency coupling capacitor to each of the two input terminals of the switch power module in the signal transmission device box at the production equipment end to obtain a high-frequency control signal. The calculation method of the capacity is the same as that of the step described in S320;

[0077] S620: decoding the high-frequency control signal obtained by capacitive coupling to obtain various corresponding sensor signals, and combining the process requirements and timing of the production process computer software to generate various control signals by calculation;

[0078] S630: Process the control signal and drive the actuator to execute to meet the needs of the production line process. The specific process is as follows:

[0079] S631: Input high frequency signal into SSR through optical coupler for signal isolation;

[0080] S632: The high-frequency pulse signal is amplified to drive the actuator to generate a control action.

[0081] Furthermore, in S400, the production process computer software is an embedded computer software "Ion Membrane Electrolysis Liquid Caustic Soda Production Process Control System V1.0", and the software is embedded and integrated with six modules: data acquisition, control algorithm, human-computer interaction, communication, fault diagnosis and safety assurance. This software is stored in a hardware medium and pre-installed on a PC, and when executed by a processor, it realizes control of the process flow of the production line.

[0082] Beneficial Effects

[0083] Compared with the prior art, the advantages of the present invention are:

[0084] 1. The present invention uses low-voltage power grid high-frequency low-frequency band narrowband communication technology to overcome the shortcomings of traditional liquid alkali production line sensing and control signal wiring transmission. It does not need to lay a large number of cables, reduces the construction cost and construction difficulty of the system, and also reduces the workload of later maintenance and upgrading.

[0085] 2. The present invention solves the problem of high requirements on frequency, frequency band and bandwidth of existing carrier communication. On the basis of fully satisfying the stable transmission of sensing and control signals and the normal operation of equipment, it fully utilizes the characteristics that the requirements of sensing and control signal communication on frequency, frequency band and bandwidth are much lower than those of voice and image transmission, reduces the interference of the system on the power grid, and reduces the technical difficulty and cost of the system.

[0086] 3. The present invention realizes refined and intelligent control of the liquid caustic soda production line through a series of operations such as collection, processing, coupled transmission of sensor signals at the production equipment end, signal reception and processing at the central control end, and signal generation, transmission, and execution under the control of computer embedded software. It effectively solves the technical problems of sensor and control signal transmission for technical upgrading and transformation of existing production lines and new production lines, helps to improve the production efficiency and product quality of liquid caustic soda production lines, and promotes the sustainable development of the salt chemical industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1 is a system flow chart of the present invention;

[0088] Figure 2 It is a flow chart of the signal transmission of the present invention;

[0089] Figure 3 The electrical engineering diagram for the transmission device of the present invention;

[0090] Figure 4 It is the overall architecture diagram of the embedded computer control software of the present invention;

[0091] Figure 5 It is the electrical schematic diagram of the control system of the embedded computer software of the present invention;

[0092] Figure 6 It is the electrical schematic diagram of the power management module of the embedded computer software of the present invention;

[0093] Figure 7 It is the electrical schematic diagram of the sensor data monitoring and processing module of the embedded computer software of the present invention;

[0094] Figure 8 This is an electrical schematic diagram of a driver execution module of the embedded computer software of the present invention;

[0095] Figure 9 This is a schematic diagram of single-end grounding of the double-layer sensor signal cable of the present invention;

[0096] Figure 10 It is a schematic diagram of the structure of the high-frequency coupled inductor coil of the present invention;

[0097] Figure 11 It is a schematic diagram of the magnetic core and skeleton of the high-frequency coupled inductor coil of the present invention.

[0098] In the figure: 1. High-frequency primary coil; 2. High-frequency annular magnetic core; 3. Coil bracket; 4. High-frequency primary coil terminal; 5. High-frequency secondary coil; 6. Magnetic gap interface; 7. High-frequency secondary coil terminal DETAILED DESCRIPTION

[0099] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, specific embodiments of the present invention are described in detail below.

[0100] This embodiment provides a sensor signal transmission system for liquid caustic soda production, comprising the following steps:

[0101] S100: collecting and processing sensor signals from production equipment;

[0102] S200: It uses inductive coupling to couple the sensor signal at the production equipment end with the power line of the low-voltage power grid, and performs high-frequency and low-frequency narrowband transmission;

[0103] S300: At the central control end, high-frequency sensor signals are acquired and processed by capacitive coupling;

[0104] S400: Input the sensor signal into the PC and generate various control signals in combination with the production process software;

[0105] S500: Processing the control signal of the central control end and coupling and transmitting it with the power line of the low-voltage power grid by inductive coupling;

[0106] S600: On the production equipment side, high-frequency sensor signals are obtained and processed by capacitive coupling;

[0107] S700: After the control instructions issued by the central control end are processed as above, they are executed in an orderly manner at the production equipment end.

[0108] Among them, in S100, the method for collecting and processing the sensor signal at the production equipment end is as follows:

[0109] S110: According to the production process requirements, for locations where dynamic physical quantity changes need to be measured, such as tank containers, pipelines, and supporting electrical appliances, necessary sensors including pressure, temperature, capacity, mass, flow rate, specific gravity, speed, voltage, and current sensors shall be installed in accordance with the principles of the same or similar raw material properties, the same or similar processes, the same or similar procedures, and the same or similar safety indicators. For example, a pressure sensor is installed on the liquid alkali raw material storage tank to monitor the pressure changes in the tank to ensure storage safety; a flow rate sensor is installed in the delivery pipeline to monitor the flow rate of liquid alkali to ensure the stability of the production process.

[0110] S120: Connect the above sensor signal to the sensor signal processing module in the signal transmitter box at the production equipment end through a multi-core signal cable with double-layer shielding, and perform corresponding operational amplification or attenuation. This embodiment selects a multi-core signal cable with an inner layer of aluminum foil wrapped and bare wire wrapped shielding, and an outer layer of braided copper mesh shielding, such as RVVP 8×0.5mm², the inner layer of aluminum foil wrapped and bare wire wrapped shielding adopts a single-terminal connection to the equipment chassis ground at the equipment end, and the outer layer of braided copper mesh shielding layer is single-terminated to the DC power supply ground (cold ground) of the signal processing module group at the production equipment end in the signal transmitter box, which is used to prevent the influence of power frequency interference (50 / 60Hz), high-frequency harmonic interference (from power electronic equipment) and common mode noise (introduced by power line coupling) on ​​the sensor signal.

[0111] Since different sensors have different output signals, for sensors with weaker output signals, such as some high-precision temperature sensors, operational amplification is required to enhance the signal strength for subsequent processing; for sensors with stronger output signals that may exceed the tolerance range of the subsequent processing module, attenuation processing is performed.

[0112] S130: Encode the sensor signal after the operation amplification or attenuation; wherein, for ordinary sensors that output analog electrical signals, it is necessary to perform analog-to-digital conversion on the sensor signal after the operation amplification or attenuation, and for digital sensors or intelligent sensors that output digital sensor signals, it is not necessary to perform analog-to-digital conversion and directly encode them. For example, ordinary pressure sensors output analog signals, which are first converted to digital signals and then encoded; while intelligent flow sensors themselves output digital signals and can be directly encoded.

[0113] S140: Modulate the encoded sensor signal with the local oscillator signal with a frequency of 200kHz carrier and a bandwidth of 2kHz generated by the frequency conversion module to generate a high-frequency low-frequency narrowband sensor signal. Through this modulation method, the sensor signal can be transmitted in a specific frequency band of the low-voltage power grid to reduce interference.

[0114] S150: After the generated narrowband sensing signals in the high and low frequency bands are amplified by high frequency, they are coupled and transmitted to the two-phase power lines of the power grid through a high-frequency coupling inductance coil.

[0115] In S150, the generated narrowband sensing signals in the high and low frequency bands are amplified by high frequency for 1 to 2 stages and then coupled and transmitted to the two-phase power lines of the power grid through a high-frequency coupling inductance coil. The specific contents are as follows:

[0116] S210: Set 3 high-frequency reactors at the front end of the secondary of the power transformer. The relevant calculation methods are as follows:

[0117] S211: Calculate the core specifications of the reactor according to the usage characteristics of the reactor. The calculation formula is as follows:

[0118]

[0119] Among them, Effective cross-sectional area of the core (unit: cm²), represents the effective magnetic path length of the core (unit: cm), L represents the target inductance (unit: H), represents the peak power frequency current (unit: A), represents the saturation magnetic flux density of the core (unit: T), represents the permeability of free space (unit: H / m), represents the relative permeability of the core material (unit: H / m), represents the effective power frequency current (unit: A);

[0120] S212: Calculate the number of turns of the high-frequency reactor coil. The calculation formula is as follows:

[0121]

[0122] Among them, represents the number of turns of the high-frequency reactor coil, represents the effective magnetic path length of the core (unit: m), L represents the target inductance (unit: H), represents the permeability of free space (unit: H / m), represents the relative permeability of the core material (unit: H / m), Effective cross-sectional area of the core (unit: cm²);

[0123] S213: Calculate the wire diameter of the reactor through the basic current capacity of the power line. The calculation formula is as follows:

[0124]

[0125] Among them, Represents the wire diameter (unit: mm), Indicates the effective current of the conductor (unit: A). Indicates the current density (usually 3 to 5 A / mm², high frequency can be reduced to 2 to 3 A / mm² ;

[0126] S214: In order to meet the dual constraints of the current capacity of the reactor and the high-frequency skin effect, the effective diameter of the conductor at high frequency should be less than 2 times the skin depth. The calculation formula is as follows:

[0127]

[0128] in, Indicates skin depth (unit: mm), Indicates the conductor resistivity (unit: Ω.m), Indicates the operating frequency (unit: Hz), Indicates the magnetic permeability of the conductor (unit: H / m). In actual design and use, the wire diameter is generally required to be: If the calculated result exceeds this value, use multiple strands of Litz wire to reduce the AC resistance.

[0129] S220: At the two input ends of the switching power supply module whose input voltage is 380V phase-to-phase voltage of the signal transmission equipment box at the production equipment end, two circular coupling magnetic rings consisting of four C-shaped semicircular magnetic rings connected and closed in pairs are provided, on which a primary coil and a secondary coil consisting of a power line are provided. The specific contents are as follows:

[0130] S221: The DC power supply of the sensor signal transmitter at the production equipment end is powered by a switching power supply module with an input voltage of 380V phase-to-phase voltage;

[0131] S222: Calculate the high-frequency impedance matching data of the coil to satisfy the high-frequency and low-frequency characteristics of the system. The calculation formula is as follows:

[0132]

[0133] in, Indicates the inductance of the high-frequency coil (unit: H), High frequency carrier circuit characteristic impedance (unit: Ω), Indicates the high-frequency carrier frequency (unit: Hz);

[0134] S223: By querying and calculating the technical parameter requirements of the circuit and combining empirical data, the technical parameters of the magnetic core are obtained. The calculation formula is as follows:

[0135]

[0136] in, Effective cross-sectional area of the magnetic core (unit: m², commonly used cm²), represents the effective magnetic path length of the magnetic core (unit: m), L represents the target inductance (unit: H), represents the peak power frequency current (unit: A), represents the saturation magnetic flux density of the magnetic core (unit: T), represents the permeability of free space (unit: H / m), represents the relative permeability of the magnetic core material (unit: H / m), in the formula , represents the effective power frequency current (unit: A);

[0137] S224: Calculate the wire diameter of the primary of the high-frequency coupled inductor coil through the effective value and current density of the high-frequency side current input by the signal. The calculation formula is as follows:

[0138]

[0139] Among them, represents the primary high-frequency side wire diameter, represents the effective value of the high-frequency current (unit: A), represents the high-frequency current density (unit: mm²);

[0140] S225: Calculate the wire diameter of the secondary of the low-frequency coupled inductor coil through the effective value and current density of the low-frequency current on the power line side of the signal coupling output side, that is, the power grid side. The calculation formula is as follows:

[0141]

[0142] Among them, represents the secondary low-frequency end wire diameter, represents the effective value of the low-frequency current (unit: A), represents the low-frequency current density (unit: mm², generally taking 3 - 5 A / mm²);

[0143] S226: Calculate the inductance of the coupled coil to calculate the number of turns of the coupled coil. The calculation formula is as follows:

[0144]

[0145] Among them, represents the inductance of the low-frequency coil (unit: H), represents the low-frequency voltage (V) represents the low-frequency carrier frequency (unit: Hz), represents the effective value of the low-frequency current (unit: A);

[0146]

[0147] in, Represents the inductance of the high-frequency coil (unit: H), represents high frequency voltage (V), Represents the high-frequency carrier frequency (unit: Hz), Represents the effective value of high-frequency current (unit: A);

[0148] S227: Calculate the number of turns of the high-frequency coil to meet the technical requirements for signal transmission. The calculation formula is as follows:

[0149]

[0150] in, Indicates the number of turns of the inductor coil, represents the effective length of the magnetic circuit (unit: m), L represents the design target inductance (unit: H), μ0 represents the vacuum permeability (unit: H / m, generally copper H / m), Relative magnetic permeability (unit: H / m), Represents the effective cross-sectional area of ​​the core (unit: mm²);

[0151] In actual design, the coupling coefficient k value of the coupling coil needs to be adjusted and optimized to make it closer to the ideal value (k≈1). The actual design should be controlled within k>0.9. The design effect can be achieved by adjusting the relative position of the magnetic core, adjusting the air gap and / or using a toroidal magnetic core.

[0152] S228: The encoded sensor signals are collected and modulated with the high-frequency signal with a frequency of 200kHz and a bandwidth of 2kHz generated by the production equipment-side signal processing module group in the production equipment-side signal transmission equipment box to generate a high-frequency sensor signal. After 1 to 2 levels of high-frequency amplification, the high-frequency coupled inductor is connected in series with the two input ends of the switching power supply module for in-phase coupling transmission.

[0153] Preferably, in S300, at the central control end, a high-frequency carrier signal is acquired by capacitive coupling and processed, including the following:

[0154] S310: The DC power supply of the sensor signal transmitter at the central control terminal is powered by a switching power supply module with an input voltage of phase to phase voltage of 380V.

[0155] S320: A high-frequency coupling capacitor is connected to each input end of the two switching power supply modules. The calculation method of its capacity is as follows:

[0156] S321: Calculate the withstand voltage value of the high-frequency coupling capacitor. First, calculate the peak value of its power frequency voltage. The calculation formula is as follows:

[0157]

[0158] Among them, represents the peak voltage (unit: V), represents the power frequency voltage value (unit: V);

[0159] S322: Through theoretical calculation and experiments, type X2 thin-film capacitors are selected here. They are suitable for suppressing crosstalk interference, and the withstand voltage level is 2.5 kV to 4 kV. Ceramic capacitors have good high-frequency characteristics, but due to their low withstand voltage, they need to be used in series.

[0160] S323: Calculate the capacitance of the high-frequency coupling capacitor. The calculation formula for its capacitance is as follows:

[0161]

[0162] Among them, represents the capacitance of the coupling capacitor (unit: nF), represents the carrier frequency (unit: Hz), represents the capacitance impedance (unit: Ω). In actual use, it should satisfy: Among them is the characteristic impedance of the power line, usually 50 Ω to 600 Ω.

[0163] Preferably, in the S400, input the high-frequency carrier signal into the PC, and generate various control signals through computer software operation combined with the production process, including the following content:

[0164] S410: Decode the high-frequency sensing signal obtained through capacitive coupling to obtain high-frequency sensing signals corresponding to different sensors and containing different sensing information. For example, after decoding, distinguish temperature sensing signals, pressure sensing signals, etc.

[0165] S420: Input the high-frequency sensing signals containing different sensing information into the corresponding signal processing modules, and send them to the PC in the central control room through amplification by an operational amplifier and optical coupling isolation. After amplification and isolation, ensure the stable and safe transmission of the signals to the PC.

[0166] S430: The PC in the central control room analyzes and judges various input sensing signals through software, and generates various control signals through operation according to the technological and timing requirements of the software. For example, when it is detected that the temperature in the liquid caustic soda reactor is too high, generate a control signal to reduce the heating power.

[0167] Preferably, in S500, the control signal of the central control terminal is processed and coupled and transmitted with the power line of the low-voltage power grid by inductive coupling, including the following contents:

[0168] S510: Encode the generated control signal through the control signal amplified by the operational amplifier.

[0169] S520: The encoded control signal is modulated with a high-frequency signal with a frequency of 200kHz and a bandwidth of 2kHz generated by the central control terminal signal processing module group in the central control terminal signal transmission equipment box to generate a high-frequency control signal. After 1-2 levels of high-frequency amplification, the high-frequency coupled inductor and the two input ends of the switching power supply module powered by the signal transmission equipment are connected in series and coupled in phase for transmission.

[0170] S530: The design, calculation and manufacturing methods of the high-frequency coupled inductor coil in the above steps are the same as those described in S220.

[0171] Preferably, in S600, at the production equipment end, a high-frequency sensing signal is obtained by capacitive coupling and processed;

[0172] S610: A high-frequency coupling capacitor is connected to each of the two input terminals of the switching power supply module in the signal transmission equipment box at the production equipment end to obtain a high-frequency control signal. The calculation method of the capacity is the same as the step described in S320.

[0173] S620: Decode the high-frequency control signal obtained through capacitive coupling to obtain various corresponding sensor signals, and combine the process requirements and timing of the production process computer software to generate various control signals.

[0174] S630: Process the control signal and drive the actuator to execute to meet the needs of the production line process. The specific process is as follows:

[0175] S631: Input high frequency signal to SSR through optocoupler (such as 4N25) for signal isolation.

[0176] S632: The high-frequency pulse signal is pushed and amplified to drive the actuator to produce control actions. Due to the characteristics of this solution, single-phase or three-phase thyristor, MOSFE tube, solid-state relay and gate drive chip are selected. For example: control the start and stop of the liquid alkali delivery pump, adjust the valve opening, etc. The above equipment is installed in the drive module box at the production equipment end.

[0177] Preferably, in S400, the production process computer software is the embedded computer software "Ion-Exchange Membrane Electrolysis Liquid Caustic Soda Production Process Control System V1.0". The software is embedded and integrated with six major modules including data acquisition, control algorithm, human-computer interaction, communication, fault diagnosis, and safety guarantee, as well as a power management module. The specific technical architecture is as follows:

[0178] MOD1, Data Acquisition Module, is responsible for real-time acquisition of key parameters such as temperature, pressure, and flow rate during the production process.

[0179] MOD2, Control Algorithm Module, uses advanced control algorithms to precisely control the production process based on the acquired data.

[0180] MOD3, Human-Computer Interaction Module, provides a friendly user interface to achieve interaction with operators for easy monitoring and control.

[0181] MOD4, Communication Module, is responsible for data exchange with other systems or devices to achieve integration and sharing of production information.

[0182] MOD5, Fault Diagnosis Module, quickly locates the cause of faults by analyzing abnormal data during the production process and gives treatment suggestions.

[0183] MOD6, Safety Guarantee Module, ensures the stable operation of the system, prevents illegal operations and data leakage, and guarantees production safety.

[0184] The technical architecture of the module is as follows:

[0185] 1. R5F523W8CDLN MCU: As the core control unit, it is responsible for processing data, executing control algorithms, and driving other modules.

[0186] 2. ISL85415 Buck Converter: Provides efficient and stable power management to ensure the stable operation of the system.

[0187] 3. HS3101 Humidity & Temperature Sensors: Real-time monitors the ambient temperature and humidity to provide accurate data support for the control algorithm.

[0188] 4. NTCALUG02A103G NTC: Responsible for temperature monitoring and control to ensure the stable production process.

[0189] 5. 2EDF7275KXUMA2 MOSFET gate-driver: Designs a high-performance drive circuit to improve the system response speed and stability.

[0190] 6. PJ-002AH Power Connector: Provides a dedicated power connection solution to ensure the stable operation of the system.

[0191] 7. 114991172 Flow Meter: Real-time collects the flow data during the production process to support the control algorithm.

[0192] This software can be selectively used according to the configuration of peripheral devices; this software is stored in a hardware medium and pre-installed on a PC, and when executed by a processor, it realizes the control of the production process flow of the production line.

[0193] Although the present invention is disclosed as above, the present invention is not limited thereto. Any person skilled in the art can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be subject to the scope defined by the claims.

Claims

1. A sensor signal transmission system for liquid caustic soda production, characterized in that: The following steps are involved: S100: collecting and processing sensor signals from production equipment; S200: It uses inductive coupling to couple the sensor signal at the production equipment end with the power line of the low-voltage power grid, and performs high-frequency and low-frequency narrowband transmission; S300: At the central control end, high-frequency sensor signals are acquired and processed by capacitive coupling; S400: Input the sensor signal into the PC and generate various control signals in combination with the production process software; S500: Processing the control signal of the central control end and coupling and transmitting it with the power line of the low-voltage power grid by inductive coupling; S600: On the production equipment side, high-frequency sensor signals are obtained and processed by capacitive coupling; S700: After the control instructions issued by the central control end are processed as above, they are executed in an orderly manner at the production equipment end.

2. A sensor signal transmission system for liquid caustic soda production according to claim 1, characterized in that: In S100, the method for collecting and processing the sensor signal at the production equipment end is as follows: S110: According to the production process requirements, for locations where dynamic physical quantity changes need to be measured, such as tank containers, pipelines, and supporting electrical appliances, necessary sensors including pressure, temperature, capacity, mass, flow rate, specific gravity, speed, voltage, and current sensors shall be installed according to the principle of the same or similar raw material properties, the same or similar processes, the same or similar procedures, and the same or similar safety indicators; S120: Connect the above sensor signal to the sensor signal processing module in the signal transmission equipment box at the production equipment end through a multi-core signal cable with double shielding, and perform corresponding operational amplification or attenuation; S130: Encoding the sensor signal after the operation amplification or attenuation; wherein, for a common sensor that outputs an analog electrical signal, it is necessary to perform analog-to-digital conversion on the sensor signal after the operation amplification or attenuation, and for a digital sensor or smart sensor that outputs a digital sensor signal, it is possible to directly encode without analog-to-digital conversion; S140: modulating the encoded sensing signal with a local oscillator signal with a frequency bandwidth of 2kHz and a carrier frequency of 200kHz generated by a frequency conversion module to generate a high-frequency low-frequency narrow-band sensing signal; S150: After high-frequency amplification, the generated high-frequency low-frequency narrow-band sensing signal is coupled and transmitted with the two-phase power line of the power grid through a high-frequency coupling inductor.

3. A sensor signal transmission system for liquid caustic soda production according to claim 2, characterized in that: In the above S150, the generated high-frequency low-frequency narrow-band sensing signal is amplified by 1-2 levels of high frequency, and then coupled and transmitted with the two-phase power lines of the power grid through the high-frequency coupling inductor, which specifically includes the following contents: S210: Three high-frequency reactors are set at the secondary front end of the power transformer, and the relevant calculation method is as follows: S211: Calculate the core specifications of the reactor according to the usage characteristics of the reactor. The calculation formula is as follows: in, Core effective cross-sectional area (unit: cm²), represents the effective magnetic path length of the core (unit: cm), L represents the target inductance (unit: H), Indicates the power frequency peak current (unit: A), Indicates the core saturation flux density (unit: T), Indicates the vacuum magnetic permeability (unit: H / m), Indicates the relative magnetic permeability of the core material (unit: H / m), Indicates the power frequency effective current (unit: A); S212: Calculate the number of turns of the high-frequency reactor coil. The calculation formula is as follows: in, Indicates the number of turns of the high-frequency reactor coil, represents the effective magnetic path length of the core (unit: m), L represents the target inductance (unit: H), Indicates the vacuum magnetic permeability (unit: H / m), Indicates the relative magnetic permeability of the core material (unit: H / m), Core effective cross-sectional area (unit: cm²); S213: Calculate the wire diameter of the reactor based on the basic current capacity of the power line. The calculation formula is as follows: in, Represents the wire diameter (unit: mm), Indicates the effective current of the conductor (unit: A). Indicates the current density (usually 3 to 5 A / mm , high frequency can be reduced to 2-3 A / mm²); S214: In order to meet the dual constraints of the current capacity of the reactor and the high-frequency skin effect, the effective diameter of the conductor at high frequency should be less than 2 times the skin depth. The calculation formula is as follows: in, Indicates skin depth (unit: mm), Indicates the conductor resistivity (unit: Ω.m), Indicates the operating frequency (unit: Hz), Indicates the magnetic permeability of the conductor (unit: H / m). In actual design and use, the wire diameter is generally required to be: If the calculated result exceeds this value, use multiple strands of Litz wire to reduce the AC resistance; S220: At the two input ends of the switching power supply module whose input voltage is 380V phase-to-phase voltage of the signal transmission equipment box at the production equipment end, two circular coupling magnetic rings consisting of four C-shaped semicircular magnetic rings connected and closed in pairs are provided, on which a primary coil and a secondary coil consisting of a power line are provided. The specific contents are as follows: S221: The DC power supply of the sensor signal transmitter at the production equipment end is powered by a switching power supply module with an input voltage of 380V phase-to-phase voltage; S222: Calculate the high-frequency impedance matching data of the coil to satisfy the high-frequency and low-frequency characteristics of the system. The calculation formula is as follows: in, Indicates the inductance of the high-frequency coil (unit: H), High frequency carrier circuit characteristic impedance (unit: Ω), Indicates the high-frequency carrier frequency (unit: Hz), S223: By querying and calculating the technical parameter requirements of the circuit and combining empirical data, the technical parameters of the magnetic core are obtained. The calculation formula is as follows: in, Core effective cross-sectional area (unit: m², usually cm²), represents the effective magnetic path length of the core (unit: m), L represents the target inductance (unit: H), Indicates the power frequency peak current (unit: A), Indicates the core saturation flux density (unit: T), Indicates the vacuum magnetic permeability (unit: H / m), Represents the relative magnetic permeability of the core material (unit: H / m), where , Indicates the power frequency effective current (unit: A); S224: Calculate the wire diameter of the primary of the high-frequency coupling inductor coil by the effective value of the high-frequency side current and the current density of the signal input, and the calculation formula is as follows: in, Represents the primary high-frequency side wire diameter, Represents the effective value of high-frequency current (unit: A), Represents high-frequency current density (unit: mm²); S225: Calculate the wire diameter of the secondary of the low-frequency coupling inductor coil by the effective value and current density of the low-frequency current on the signal coupling output side, i.e., the power line side of the power grid. The calculation formula is as follows: in, Represents the secondary low-frequency end wire diameter, Represents the effective value of low-frequency current (unit: A), Represents low-frequency current density (unit: mm², generally 3-5A / mm²); S226: Calculate the inductance of the coupling coil to calculate the number of turns of the coupling coil. The calculation formula is as follows: in, Represents the inductance of the low-frequency coil (unit: H), represents the low frequency voltage (V), Represents the low-frequency carrier frequency (unit: Hz), Represents the effective value of low-frequency current (unit: A); in, Represents the inductance of the high-frequency coil (unit: H), represents high frequency voltage (V), Represents the high-frequency carrier frequency (unit: Hz), Represents the effective value of high-frequency current (unit: A); S227: Calculate the number of turns of the high-frequency coil to meet the technical requirements for signal transmission. The calculation formula is as follows: in, Indicates the number of turns of the inductor coil, represents the effective length of the magnetic circuit (unit: m), L represents the design target inductance (unit: H), μ0 represents the vacuum permeability (unit: H / m, generally copper H / m), Relative magnetic permeability (unit: H / m), Represents the effective cross-sectional area of ​​the core (unit: mm²); S228: The encoded sensor signals are collected and modulated with the high-frequency signal with a frequency of 200kHz and a bandwidth of 2kHz generated by the production equipment-side signal processing module group in the production equipment-side signal transmission equipment box to generate a high-frequency sensor signal. After 1 to 2 levels of high-frequency amplification, the high-frequency coupled inductor is connected in series with the two input ends of the switching power supply module for in-phase coupling transmission.

4. The sensor signal transmission system for liquid caustic soda production according to claim 1 is characterized in that: In S300, the central control end uses capacitive coupling to obtain a high-frequency carrier signal and processes it, including the following: S310: The DC power supply of the sensor signal transmitter at the central control terminal is powered by a switching power supply module with an input voltage of 380V phase-to-phase voltage; S320: A high-frequency coupling capacitor is connected to each input end of the two switching power supply modules, and the calculation method of the capacity is as follows: S321: Calculate the withstand voltage of the high-frequency coupling capacitor. First, calculate the peak value of its power frequency voltage using the following formula: in, Represents the peak voltage (unit: V) Represents the power frequency voltage value (unit: V); S322: Through theoretical calculation and experiment, X2 film capacitors are selected here, which are suitable for cross-line interference suppression and have a withstand voltage level of 2.5kV to 4kV. Ceramic capacitors have good high-frequency characteristics, but due to their low withstand voltage, they need to be used in series; S323: Calculate the capacity of the high-frequency coupling capacitor. The calculation formula for the capacity is as follows: in, Represents the capacity of the coupling capacitor (unit: nF), represents the carrier frequency (unit: Hz), Represents the capacitance impedance (unit: Ω), which should meet the following requirements in actual use: in It is the characteristic impedance of the power line, usually 50Ω~600Ω.

5. The sensor signal transmission system for liquid caustic soda production according to claim 1 is characterized in that: In S400, the high-frequency carrier signal is input into a PC, and various control signals are generated by combining the production process computer software operation, including the following: S410: decoding the high-frequency sensing signal obtained by capacitive coupling to obtain high-frequency sensing signals corresponding to different sensors and containing different sensing information; S420: inputting the high-frequency sensor signals containing different sensor information into the corresponding signal processing module, amplifying them through operational amplifiers and optical coupling isolation, and sending them to the PC in the central control room; S430: The PC in the central control room uses software to analyze and judge various input sensor signals, and generates various control signals based on the process and timing requirements of the software.

6. The sensor signal transmission system for liquid caustic soda production according to claim 1 is characterized in that: In S500, the processing of the control signal from the central control terminal and coupling and transmitting the signal with the power line of the low-voltage power grid by inductive coupling includes the following: S510: encoding the generated control signal through the control signal amplified by the operational amplifier; S520: modulate the encoded control signal with a high-frequency signal with a frequency of 200kHz and a bandwidth of 2kHz generated by the central control terminal signal processing module group in the central control terminal signal transmission device box to generate a high-frequency control signal, and after 1-2 levels of high-frequency amplification, connect the high-frequency coupling inductor coil and the two input ends of the switching power supply module powered by the signal transmission device in series and in-phase coupling transmission; S530: The design, calculation and manufacturing methods of the high-frequency coupled inductor coil in the above steps are the same as those described in S220.

7. The sensor signal transmission system for liquid caustic soda production according to claim 1 is characterized in that: In S600, at the production equipment end, a high-frequency sensor signal is obtained by capacitive coupling and processed; S610: Connect a high-frequency coupling capacitor to each of the two input terminals of the switch power module in the signal transmission device box at the production equipment end to obtain a high-frequency control signal. The calculation method of the capacity is the same as that of the step described in S320; S620: decoding the high-frequency control signal obtained by capacitive coupling to obtain various corresponding sensor signals, and combining the process requirements and timing of the production process computer software to generate various control signals by calculation; S630: Process the control signal and drive the actuator to execute to meet the needs of the production line process. The specific process is as follows: S631: Input high frequency signal into SSR through optical coupler for signal isolation; S632: The high-frequency pulse signal is amplified to drive the actuator to generate a control action.

8. A sensor signal transmission system for liquid caustic soda production according to claim 7, characterized in that: In S400, the production process computer software is an embedded computer software "Ion Membrane Electrolysis Liquid Caustic Soda Production Process Control System V1.0", which is embedded with and integrates six modules: data acquisition, control algorithm, human-computer interaction, communication, fault diagnosis and safety assurance. The software is stored in a hardware medium and pre-installed on a PC, and controls the process flow of the production line when executed by a processor.

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