CN110541812A - Energy-saving air compressor control system and method based on DCS comprehensive control - Google Patents

Abstract

the invention provides an energy-saving air compressor control system and method based on DCS (distributed control system) overall control, wherein the energy-saving air compressor control system based on DCS overall control comprises a compressor unit, an electrical unit and a DCS control unit; the DCS control unit comprises a signal collector group and a DCS controller; the signal collector group is used for monitoring the running states of the electrical unit and the compressor group; and the electric unit controls the compressor unit to start, load, unload or stop according to the instruction sent by the DCS control unit. According to the energy-saving air compressor control system based on DCS comprehensive control, the DCS controller is adopted to control the compressor unit in real time, so that the operation of the compressor unit is more reasonable, and the operation energy consumption of the compressor unit can be reduced; meanwhile, data obtained by scanning of the DCS controller can be stored in a DCS historical database, so that the historical working condition of the equipment in any period of the whole life cycle can be read back, and the requirements of fault analysis and equipment optimization are fully met.

Description

Energy-saving air compressor control system and method based on DCS comprehensive control

Technical Field

The invention relates to the field of air compressor control, in particular to an energy-saving air compressor control system and method based on DCS (distributed control system) overall control.

Background

In recent years, the popularization of energy-saving products is continuously increased in China, and the development of energy-saving technology of the air compressor as a product applied to multiple industrial fields such as domestic mines, metallurgy, electric power, electronics, mechanical manufacturing, medicines, foods, textile light industry, petrochemical industry and the like has great significance to the energy-saving industry of China.

The existing active air compressor in the industrial field mainly has the following main problems. Firstly, most air compressors are originally designed and still based on a single chip microcomputer or early PLC, and a control strategy cannot be modified after being packaged and latched; secondly, the process control is simple, the adjustment precision of working condition parameters is poor, most pressure adjustment control modes are still rough mechanical pneumatic adjustment systems, the optimal point of the output adjustment of the compressor is only in the middle output section of the standard design, the linear area is narrow, the unbalance can be adjusted once the load change of a user is large, and the energy-saving efficiency is extremely low; thirdly, working condition parameters of the air compressor cannot be recalled, even the latest product can only inquire customized fault alarms within limited times, full working condition information when a fault occurs cannot be reproduced, and fault analysis cannot be effectively supported; and fourthly, the air compressor is limited by the control of a low-end single chip microcomputer and a PLC (programmable logic controller) packaged by an original factory, even if a majority of industrial enterprise main production service systems adopt an advanced industrial DCS (distributed control system) and can accept various data communication protocols such as Modbus, RS-232, RS-485 and the like, the air compressor has no data communication protocol interface, cannot exchange data with an external system, cannot improve the control precision by utilizing the superior performance of the advanced industrial control system, and becomes an information isolated island and a control short board.

under the combined action of the social background and the current technical situation, most industrial enterprises are seriously worried about energy-saving modification projects of the air compressor, and although the working condition of the main engine of the air compressor is still good, a whole set of meat cutting modification mode for replacing new meat is finally adopted to solve the urgent need of energy saving. In the current sales market, a common air compressor with the volume flow rate of more than or equal to 30m3/min needs about 30-50 ten thousand yuan, 3 or more air compressor stations are generally arranged in an industrial enterprise to form a set of air compressor station design mode, the cost of labor materials is superposed, 150 ten thousand yuan is needed for one-time thorough energy-saving transformation of the air compressor station, and the recovery period of the generated energy-saving benefit is usually more than 10 years.

Disclosure of Invention

In order to overcome the defects in the prior art, the invention provides the energy-saving air compressor control system and method based on DCS comprehensive control, which can be used for modifying the existing air compressor system at low cost, is particularly suitable for the situation of the existing industrial DCS control system of an industrial enterprise and achieves good energy-saving benefit.

In order to achieve the aim, the invention provides an energy-saving air compressor control system based on DCS comprehensive control, which comprises a compressor unit, an electrical unit, a signal collector group and a DCS control unit; the signal collector group is used for monitoring the running states of the electrical unit and the compressor unit; the DCS control unit sends out different control instructions according to the information fed back by the signal collector group; and the electrical unit controls the compressor unit to start, load, unload or stop according to the instruction sent by the DCS control unit.

Further, the compressor unit comprises an air filter, an electric regulating valve, a pneumatic valve, a compressor, an oil-gas barrel separator, an oil filter, a cooler and an outlet screwing valve; the air filter, the electric regulating valve, the pneumatic valve, the compressor, the oil-gas barrel separator cooler, the outlet screwing valve and the compressed gas main pipe are sequentially connected to form a compressed gas circuit; the top of the oil-gas barrel separator is connected to the front of the pneumatic valve through a discharge solenoid valve to form a discharge gas path; and an outlet pipe of the oil-gas barrel separator is connected to a driving cylinder of the pneumatic valve through a loading electromagnetic valve to form a loading gas circuit.

Further, the electric unit comprises a power supply end, an emergency stop button, a main motor contactor, a main motor star-shaped contactor and a main motor triangular contactor, wherein the main motor contactor, the main motor star-shaped contactor and the main motor triangular contactor are used for controlling power supply of the compressor motor, a cooling fan contactor is used for controlling power supply of the cooling fan motor, and the three electric branches are respectively used for controlling power supply of the electric regulating valve, the release electromagnetic valve and the loading electromagnetic valve.

Further, the signal collector group includes, but is not limited to, an air-filter differential pressure switch PS1, a main motor temperature switch TS, a main motor current transmitter I, a thermocouple relay TH, a phase sequence protector PH, an oil-filter differential pressure switch PS2, a separator pressure transmitter P3, a separator temperature sensor T2, an exhaust port temperature sensor T1, an exhaust port pressure transmitter P1, a closed water pressure transmitter P4, a compressed gas main pipe pressure transmitter P2, an electric control valve position feedback VZ, a main motor contactor feedback contact CM, a main motor star contactor feedback contact CS, a main motor delta contactor feedback contact CD, a cooling fan contactor feedback contact CF, and an emergency stop button feedback contact CE.

Further, the DCS unit comprises a DCS controller, an input module, an output module and a human-computer interface; the human-computer interface comprises but is not limited to a starting control signal input interface, a stopping control signal input interface, an electric control valve control instruction input interface and a display interface.

The invention also provides an energy-saving air compressor control method based on DCS overall control, which is applied to any one of the energy-saving air compressor control systems based on DCS overall control; the method comprises the following steps:

And the DCS controller scans the signal collector group in real time and controls the compressor unit to enter a starting process, a loading process, an unloading process or a stopping process according to data fed back by the signal collector group.

Further, the starting procedure comprises the following steps:

step S11: if the DCS controller receives an interlocking starting instruction FR or a starting control signal KR, the DCS controller sends a main motor contactor control signal KM, a main motor star-shaped contactor control signal KS and a cooling fan contact control signal KF, so that a main motor, a main motor star-shaped loop and a cooling fan motor are started; the interlocking starting instruction is that the deviation of a compressed gas main pipe pressure transmitter P2 is lower than a set value, the PH of a main motor phase sequence protector, a thermocouple relay TH and a temperature switch TS are not closed, and the disconnection time of a feedback contact CM of a main contactor meets the set value;

Step S12: after the main motor star-shaped loop is started, if the DCS controller receives a main motor loop switching permission instruction F delta, the DCS controller sends a main motor triangle contactor control signal KD, disconnects a main motor star-shaped contactor control signal KS, and switches the main motor star-shaped loop into a triangle loop to complete the starting of the compressor unit; the phase sequence protector PH, the thermocouple relay TH and the main motor temperature switch TS are not actuated, the closing time of the main contactor feedback contact CM and the star contactor feedback contact CS meets the set value, and the signal quality of the main motor current transmitter I is good.

further, the shutdown process comprises the following steps:

Step S21: if the DCS controller receives an electric protection shutdown loop instruction FSE, a thermal protection shutdown loop instruction FST or an automatic shutdown loop instruction FSA, the DCS controller sends an unloading instruction, a locking loading instruction and a locking output adjusting instruction, and disconnects a main motor contactor control signal KM, a main motor star-shaped contactor control signal KS, a main motor triangle-shaped contactor control signal KD and a cooling fan contact control signal KF to complete shutdown of the compressor unit; wherein, the FSE is TH + CE + PH + TS, namely at least one action of the thermocouple relay TH, the emergency stop button feedback contact CE, the phase sequence protector PH and the main motor temperature switch TS; FST-OT 1+ OP1, i.e. the exhaust port temperature sensor T1 exceeds the shutdown protection set point, or the exhaust port pressure transmitter P1 exceeds the shutdown protection set point; namely, the closing time of the control signal of the bleed-off electromagnetic valve meets the set value and the deviation of the pressure transmitter P2 of the compressed air main pipe is not lower than the set value;

Or when the DCS controller receives the stop control signal KT, the DCS controller sends an unloading instruction, continuously unloads and locks loading and output regulation, and when the pressure transmitter P3 of the separator is lower than a set value or the continuous on-time of the control signal KU of the discharge solenoid valve reaches the set value, the control signal KM of the main motor contactor, the control signal KS of the main motor star-shaped contactor, the control signal KD of the main motor triangle-shaped contactor and the contact control signal KF of the cooling fan are disconnected, so that the compressor unit is stopped.

Further, the loading process comprises the following steps:

step S31: if the DCS controller receives a loading permission instruction FL, the DCS controller sends a loading electromagnetic valve control signal KL to connect a loading gas circuit and disconnect a discharge electromagnetic valve control signal KU, wherein on the premise that a stop instruction FS is not triggered, the air compressor starts to complete the star-delta switching for the first time, or the pressure transmitter P1 at the exhaust port is reduced to a loading threshold value and the main motor completes the star-delta switching;

step S32: after a loading gas circuit is connected, if a DCS controller receives a loading adjustment permission instruction FC, the DCS controller is allowed to send an electric adjusting valve control instruction VS, and the electric adjusting valve control instruction VS is used as an output variable and a controlled variable P1 to adopt a PID operation loop to realize the loading adjustment of the air compressor; where FC is FL · Δ P1 · QI · QV, i.e., the load-permit command FL exists, the exhaust port pressure transmitter P1 deviates beyond the regulation dead band, the main motor current transmitter I signal quality is good and the electrical regulator valve position feedback VZ signal quality is good.

Further, the unloading process comprises the following steps:

Step S41: if the DCS controller receives the interlocking unloading instruction FU, the DCS controller sends a discharge solenoid valve control signal KU to connect an unloading gas circuit and disconnect a loading solenoid valve control signal KL to realize unloading of the air compressor; wherein either the main motor has started but not completed the star-delta switch, or the vent pressure transmitter P1 rises to the unload threshold and the main motor completes the star-delta switch to begin doing work, or a shutdown command FS exists.

according to the energy-saving air compressor control system based on DCS comprehensive control, the running state of the compressor set is monitored by installing the signal collector group on the compressor set; the DCS controller is adopted to periodically scan the signal collector group so as to obtain the current running state of the compressor unit in real time, and a corresponding DCS control strategy is formulated, so that the compressor unit can switch the working procedures of running starting, loading, unloading, stopping and the like according to the working conditions, the running of the compressor unit is more reasonable, and the running energy consumption of the compressor unit can be reduced; meanwhile, data obtained by scanning of the DCS controller can be stored in a DCS historical database, so that the historical working condition of the equipment in any period of the whole life cycle can be read back, and the requirements of fault analysis and equipment optimization are fully met.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and those skilled in the art can also obtain other drawings according to the drawings without creative efforts.

fig. 1 is a schematic structural diagram of an energy-saving air compressor control system based on DCS overall control according to the present invention;

FIG. 2 is a schematic flow chart of a start-up procedure provided by the present invention;

FIG. 3 is a schematic flow chart of a stopping process provided by the present invention;

FIG. 4 is a schematic flow chart of a loading process provided by the present invention;

FIG. 5 is a schematic flow chart of an unloading process provided by the present invention;

FIG. 6 is a logic diagram of a start-up procedure and a stop procedure provided by the present invention;

Fig. 7 is a logic diagram of a loading process and an unloading process according to the present invention.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are some, but not all, embodiments of the present invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

in the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate orientations or positional relationships based on those shown in the drawings, and are only for convenience of description and simplicity of description, but do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and thus, should not be construed as limiting the present invention. Moreover, the use of "first," "second," and similar language does not denote any order, quantity, or importance, but rather the components are distinguished. The terms "connected" or "coupled" and the like are not restricted to physical or mechanical connections, but may include electrical connections, whether direct or indirect.

As shown in fig. 1, the invention provides an energy-saving air compressor control system based on DCS overall control, which includes a compressor unit, an electrical unit, a signal collector group and a DCS control unit; the signal collector group is used for monitoring the running states of the electrical unit and the compressor unit; the DCS control unit sends out different control instructions according to the information fed back by the signal collector group; and the electrical unit controls the compressor unit to start, load, unload or stop according to the instruction sent by the DCS control unit.

In specific implementation, as shown in fig. 1, the compressor unit includes an air filter, an electric control valve, a pneumatic valve, a compressor, an oil-gas barrel separator, an oil filter, a cooler, and an outlet screw valve; the air filter, the electric regulating valve, the pneumatic valve, the compressor, the oil-gas barrel separator cooler and the outlet screwing valve are connected to a compressed gas main pipe in sequence to form a compressed gas circuit; after being filtered by an air filter, the outside air enters the compressor through an electric regulating valve and an air inlet pipeline where a pneumatic valve is arranged; the oil-gas mixed compressed gas is formed under the action of a compressor, and the oil-gas mixed compressed gas passes through an oil-gas barrel separator to form compressed air and lubricating oil; compressed air is output from an outlet pipe of the oil-gas barrel separator, is cooled by a cooler and then enters a compressed air main pipe through an outlet screwing valve to be supplied to a user; the lubricating oil separated by the oil-gas barrel separator is cooled by a cooler and filtered by an oil filter, and then returns to the compressor to continuously support compression and do work; preferably, the cooler is a closed water cooler.

As shown in fig. 1, the top of the oil-gas barrel separator is connected to the pneumatic valve through a discharge solenoid valve to form a discharge gas path; an outlet pipe of the oil-gas barrel separator is connected to a driving cylinder of the pneumatic valve through a loading electromagnetic valve to form a loading gas circuit.

As shown in fig. 1, the electric unit includes a power supply terminal, an emergency stop button, a main motor contactor M, a main motor star-shaped contactor S, and a main motor delta-shaped contactor D for controlling power supply of the compressor motor, a cooling fan contactor F for controlling power supply of the cooling fan motor, and three electric branches for controlling power supply of the electric control valve, the bleed-off solenoid valve, and the load solenoid valve, respectively; when the star-shaped contactor of the main motor works, a power supply loop of the main motor is in a star-shaped connection mode; when the triangular contactor of the main motor works, the power supply loop of the main motor is in a triangular connection mode; the emergency stop button is connected in series between the power supply end and the main motor contactor M, the main motor star-shaped contactor S, the main motor triangular contactor D and the cooling fan contactor F, and when the emergency stop button is disconnected, the main motor contactor M, the main motor star-shaped contactor S, the main motor triangular contactor D and the cooling fan contactor F are all powered off to stop working.

As shown in fig. 1, the signal acquisition device group includes, but is not limited to, an air-filter differential pressure switch PS1, a main motor temperature switch TS, a main motor current transmitter I, a thermocouple relay TH, a phase sequence protector PH, an oil-filter differential pressure switch PS2, a separator pressure transmitter P3, a separator temperature sensor T2, an exhaust port temperature sensor T1, an exhaust port pressure transmitter P1, a closed water pressure transmitter P4, a compressed gas main pipe pressure transmitter P2, an electric control valve position feedback VZ, a main motor contactor feedback contact CM, a main motor star contactor feedback contact CS, a main motor delta contactor feedback contact CD, a cooling fan contactor feedback contact CF, and an emergency stop button feedback contact CE.

Wherein, the air filter pressure difference switch PS1 is used for detecting whether the air filter is blocked; the main motor temperature switch TS is arranged near the main motor of the compressor, and is disconnected when the temperature of the main motor reaches a set threshold value; the main motor current transmitter I, the thermocouple relay TH and the phase sequence protector PH are all connected in series on a power supply loop of a main motor of the compressor, the main motor current transmitter I is used for detecting the power supply current of the main motor, the thermocouple relay TH is used for disconnecting the power supply of the main motor when the power supply current of the main motor is too large, and the phase sequence protector PH is used for disconnecting the power supply of the main motor when the power supply phase sequence connected into the main motor is wrong.

The oil filter differential pressure switch PS2 is used for detecting whether the oil filter is blocked; the separator pressure transmitter P3 and the separator temperature sensor T2 are respectively used for detecting the internal air pressure of the oil-gas barrel separator and the temperature of the oil-gas barrel separator; the exhaust port temperature sensor T1 and the exhaust port pressure transmitter P1 are respectively used for the temperature of the exhaust port and the air pressure of the exhaust port; the closed water pressure transmitter P4 is used for detecting the internal pressure of a cooling water pipeline of the cooler; the compressed manifold pressure transmitter P2 is used to detect the internal air pressure of the compressed manifold.

The DCS control unit comprises a DCS controller, an input module, an output module and a human-computer interface; the human-computer interface comprises but is not limited to a starting control signal input interface, a stopping control signal input interface, an electric control valve control instruction input interface and a display interface, and the input module, the output module and the human-computer interface are electrically connected with the DCS controller. The system comprises a start control signal input interface, a stop control signal input interface, an electric regulating valve control instruction input interface, a DCS controller and a control signal output interface, wherein the start control signal input interface is used for inputting a start control signal KR to the DCS controller, the stop control signal input interface is used for inputting a stop control signal KT to the DCS controller, and the electric regulating valve control instruction input interface is used for inputting an electric regulating valve control instruction VS to the DCS controller; the starting control signal input interface, the stopping control signal input interface and the electric control valve control instruction input interface can be electric switch elements such as keys and buttons which are electrically connected with the DCS controller, and can also be virtual input interfaces integrated on a display interface.

The display interface comprehensively displays signals of a main motor current transmitter I, a separator pressure transmitter P3, a separator temperature sensor T2, an exhaust port temperature sensor T1, an exhaust port pressure transmitter P1, a closed water pressure transmitter P4, a compressed air main pipe pressure transmitter P2, electric control valve position feedback VZ, a main motor contactor feedback contact CM, a main motor star-shaped contactor feedback contact CS, a main motor triangle-shaped contactor feedback contact CD, a cooling fan contactor feedback contact CF, an emergency stop button feedback contact CE and the like, and serves as an air compressor state display query interface, and meanwhile, the display interface can also generate an alarm pop-up window to summarize and display fault signal alarms of an air filter differential pressure switch PS1, an emergency stop button feedback contact CE, a main motor temperature switch TS, a thermocouple relay TH, a phase sequence protector PH 2 and the like.

In the embodiment of the invention, an air filtering differential pressure switch PS1, a main motor temperature switch TS, a thermocouple relay TH, a phase sequence protector PH, an oil filtering differential pressure switch PS2, a main motor contactor feedback contact CM, a main motor star-shaped contactor feedback contact CS, a main motor triangle-shaped contactor feedback contact CD, a cooling fan contactor feedback contact CF and an emergency stop button feedback contact CE are connected to a DCS switching value input module;

A main motor current transmitter I, a separator pressure transmitter P3, a separator temperature sensor T2, an exhaust port temperature sensor T1, an exhaust port pressure transmitter P1, a closed water pressure transmitter P4, a compressed gas main pipe pressure transmitter P2 and an electric regulating valve position feedback VZ are connected to a DCS analog quantity input module;

The functional logic module can output a main motor contactor control signal KM, a main motor star-shaped contactor control signal KS, a main motor triangle-shaped contactor control signal KD, a cooling fan contact control signal KF, a discharge electromagnetic valve control signal KU and a loading electromagnetic valve control signal KL through the DCS switching value output module, and output an electric control valve control command VS through the DCS analog value output module.

The invention also provides an energy-saving air compressor control method based on DCS overall control, which is applied to any one of the energy-saving air compressor control systems based on DCS overall control; the method comprises the following steps:

and the DCS controller scans the signal collector group in real time and controls the compressor unit to enter a starting process, a loading process, an unloading process or a stopping process according to data fed back by the signal collector group.

Specifically, the DCS controller performs cyclic scanning on the signal collector group at a fixed period of less than 1 second, stores data obtained through scanning into a DCS historical database, sets the data to be stored for a certain time (such as 2190 days), realizes the reading back of historical working conditions at any time period in the whole life cycle of the equipment, and fully meets the requirements of fault analysis and equipment optimization.

As shown in fig. 2, the start-up process of the present invention comprises the steps of:

step S11: if the DCS controller receives an interlocking starting instruction FR or a starting control signal KR, the DCS controller sends a main motor contactor control signal KM, a main motor star-shaped contactor control signal KS and a cooling fan contact control signal KF, so that a main motor, a main motor star-shaped loop and a cooling fan motor are started; the interlocking starting instruction is that the deviation of a compressed gas main pipe pressure transmitter P2 is lower than a set value, the phase sequence protector PH, the thermocouple relay TH and the main motor temperature switch TS are not closed, and the disconnection time of a feedback contact CM of the main contactor meets the set value;

As shown in fig. 6, in the specific implementation of step S11, the main contactor feedback contact CM enters the first TD _ ON hysteresis position type timer function block through the first NOT logic non-function block, after the duration time is determined to be greater than the set value (e.g. 60S), the off-time of the main contactor feedback contact CM with a value of 1 is sent out, so that the signal main motor temperature switch TS passes through the second NOT logic non-function block, the thermocouple relay TH passes through the third NOT logic non-function block, AND the phase sequence protector PH passes through the fourth NOT logic non-function block, the three are jointly sent into the second AND logic AND function block, when the TS, TH, AND PH are all 0, the protection trip non-signal compressed air main pipe pressure transmitter P2 with a value of 1 passes through the fourth HLALM high-low limit determination module, the compressed air main pipe pressure low signal P2L (e.g. lower than 730Kpa) AND the DCS screen start control signal KR are jointly sent into the first OR logic OR function block, AND when any input signal is 1, a boolean signal with a value of 1 is output, AND when the output signal of the first OR logic OR function block AND the break time of the feedback contact point CM of the main contactor meet the requirement of a signal AND a protection tripping non-signal, the signals AND the protection tripping non-signal are jointly transmitted into the first AND logic AND function block, AND when the output signal, the break time of the feedback contact point CM of the main contactor AND the protection tripping non-signal are all 1, an interlocking start instruction with the value of 1 is transmitted to an override input pin of the EMD1 of the first DEVICE digital manual operator function block, an air compressor start instruction FSTR with the output value of 1 of the output pin of the OUT1 of the first DEVICE digital manual operator function block is forced to be transmitted into a set end of the first RS trigger function block, a main motor contactor control signal KM AND a cooling fan contact control signal KF are transmitted, AND a main motor star contactor control signal KS is. Meanwhile, the CM off time of the main contactor meets the requirement that the signal AND the protection trip non-signal are jointly sent into a third AND logic AND functional block AND then sent into a D1P pin of a first DEVICE digital manual operator functional block as a starting permission signal, so that the output of an OUT1 output pin is permitted.

Step S12: after the main motor star-shaped loop is started, if the DCS controller receives a main motor loop switching permission instruction F delta, the DCS controller sends a main motor triangle contactor control signal KD, disconnects a main motor star-shaped contactor control signal KS, and switches the main motor star-shaped loop into a triangle loop to complete the starting of the compressor unit; the phase sequence protector PH, the thermocouple relay TH and the main motor temperature switch TS do not trigger protection action, the closing time of the main contactor feedback contact CM and the star contactor feedback contact CS meets set values, and the signal quality of the main motor current transducer I is good; in the embodiment of the invention, the good signal quality of the main motor current transducer I indicates that the current value detected by the main motor current transducer I is in a set current range.

as shown in fig. 6, in the specific implementation of step S12, the current value I detected by the main motor current transmitter I is determined by the first HLALM high-low limit determining module, and is output from the pin D of the first HLALM high-low limit determining module to the twelfth NOT logic non-functional block, and if the main motor current is in the set current range (e.g. 350> I >50), a main motor current quality signal QI with a value of 1 is sent; after a feedback contact CM of the main contactor AND a feedback contact CS of the star contactor are sent into a fourth AND logic AND function block for judgment, a star start feedback signal is output to a first Timer function block, a Boolean signal with the value of 1 is sent out after 8 seconds of timing, the Boolean signal, a protection trip non-signal AND a main motor current quality signal QI enter a fifth AND logic AND function block together, when input signals of the fifth AND logic AND function block are both 1, a main motor loop switching permission instruction F delta with the value of 1 is sent out, the main motor loop switching permission instruction F delta AND an air compressor shutdown instruction FSTP (detailed description is shown in step S21) are sent into a seventh OR logic OR function block together, when any signal is 1, a Boolean with the value of 1 is sent out, the main motor star contactor control signal KS is disconnected at a reset end of a second RS trigger function block, a main motor loop switching permission instruction F delta is simultaneously sent to a set end of a third RS trigger, AND a main motor triangle contactor control signal KD is output, and finishing the switching of the star-delta starting mode of the air compressor.

As shown in fig. 3, the shutdown process of the present invention comprises the steps of:

step S21: if the DCS controller receives an electric protection shutdown loop instruction FSE, a thermal protection shutdown loop instruction FST or an automatic shutdown loop instruction FSA, the DCS controller sends an unloading instruction, and disconnects a main motor contactor control signal KM, a main motor star-shaped contactor control signal KS, a main motor triangle-shaped contactor control signal KD and a cooling fan contact control signal KF to complete shutdown of the compressor unit; the electric protection shutdown loop instruction FSE is TH + CE + PH + TS, namely the thermocouple relay TH, and at least one of the emergency stop button feedback contact CE, the phase sequence protector PH and the main motor temperature switch TS triggers the protection action; the thermotechnical protection shutdown loop command FST is OT1+ OP1, namely the exhaust port temperature sensor T1 exceeds the shutdown protection set value, or the exhaust port pressure transmitter P1 exceeds the shutdown protection set value; the automatic shutdown loop instruction is that the closing time of the control signal of the bleed-off electromagnetic valve meets a set value and the deviation of the pressure transmitter P2 of the compressed gas main pipe is not lower than the set value;

Or if the DCS controller receives the stopping control signal KT, the DCS controller sends an unloading instruction, continuously unloads and locks loading and output adjustment. And when the pressure transmitter P3 of the separator is lower than a set value or the continuous on-time of the control signal KU of the discharge solenoid valve reaches the set value, disconnecting the control signal KM of the main motor contactor, the control signal KS of the main motor star-shaped contactor, the control signal KD of the main motor triangle-shaped contactor and the control signal KF of the cooling fan contact to complete the shutdown of the compressor unit.

preferably, the thermocouple relay TH and the emergency stop button are connected in series between the power supply terminal and each contactor, and when the thermocouple relay TH and the emergency stop button are triggered, the main motor contactor M, the main motor star-shaped contactor S, and the main motor delta-shaped contactor D are powered off and disconnected.

As shown in fig. 6, in the specific implementation of step S21, the emergency stop button contact CE, the main motor temperature switch TS signal, the thermocouple relay TH signal, and the phase sequence protector PH signal enter the second OR logic OR function block, and any input signal thereof is 1, and the electrical protection shutdown loop command FSE with the value 1 is output. And the exhaust port temperature sensor T1 and the exhaust port pressure transmitter P1 are respectively sent to a second HLALM high-low limit judgment functional block and a third HLALM high-low limit judgment functional block, the judgment results of the two functional blocks are jointly sent to a third OR logic OR functional block, and if any signal is 1, a thermotechnical protection shutdown loop instruction FST with the output value of 1 is output.

The compressed air main pipe pressure transmitter P2 is judged by the fourth HLALM high-low limit judgment function block, a compressed air main pipe pressure low signal P2L is output, the compressed air main pipe pressure low non-signal opening discharge magnetic valve control signal KU is output after the fifth NOT logic non-function block, the opening duration of the discharge magnetic valve with the value of 1 is sent out after the duration is judged to be greater than a set value (for example, 600 seconds) by the second TD _ ON hysteresis setting type timer function block, the opening duration meets the signal dTKU, the signal AND the signal enter a sixth AND logic AND function block together, AND when the input signals are all 1, an automatic shutdown loop instruction FSA with the value of 1 is sent out. The FSE, FST and FSA jointly enter a fourth OR logic OR functional block, and a shutdown command FS is output if any input signal of the fourth OR logic OR functional block is 1.

The shutdown instruction FS AND the DCS screen stop control signal KT enter a fifth OR logic OR function block together, AND if any input signal is 1, a boolean signal with a value of 1 is output, as shown in fig. 7, the boolean signal enters a tenth OR logic OR function block together with an output signal of an eleventh AND logic AND function block AND an output signal of a twelfth AND logic AND function block, AND after passing through the eleventh OR logic OR function block, the output signal of the tenth OR logic OR function block enters a first PID operation function block to lock an input pin, so as to lock the electric control valve control instruction VS; meanwhile, the output signal of the tenth OR logic OR function block also enters a second DEVICE digital manual operator function block, namely a second EMD2 override input pin, and forces the output value of the output pin of the second DEVICE digital manual operator function block OUT2 to be 1 boolean quantity to be sent to the reset end of the fourth RS trigger function block and the set end of the fifth RS trigger function block, so as to send OUT a discharge opening solenoid valve control signal KU and disconnect a load solenoid valve control signal KL.

when the control signal KU of the leakage electromagnetic valve enters a third TD _ ON hysteresis setting type timer functional block, the shutdown unloading time with the value of 1 is sent out after the judgment duration is longer than the set value (such as 15 seconds), and the separator pressure transmitter P3 outputs a Boolean signal with the value of 1 when the judgment duration is shorter than the set value (such as 150Kpa) through a fifth HLALM high-low limit judgment functional block, and the first and second logic OR functional blocks enter an eighth OR logic OR functional block together; if any input signal of the eighth OR logic OR functional block is 1, outputting a Boolean signal with the value of 1; AND the output signal of the eighth OR logic OR functional block AND the DCS picture stop control signal KT enter a seventh AND logic AND functional block together, AND when the input signal of the seventh AND logic AND functional block is 1, a stop control low signal KTL which is used for disconnecting the main contactor AND has the value of 1 is sent out.

The stop command FS and the stop control low signal KTL jointly enter a sixth OR logic OR function block, if any input signal is 1, a Boolean signal with the value of 1 is output to a second EMD2 override input pin of the first DEVICE digital manual operator function block, an air compressor stop command FSTP with the output value of 1 is forced to be output by an OUT2 of the first DEVICE digital manual operator function block, the air compressor stop command FSTP is sent to a reset end of the first RS trigger function block to disconnect a main motor contactor control signal KM and a cooling fan contact control signal KF, and the air compressor stop command FSTP is also sent to a reset end of the third RS trigger function block to disconnect a main motor triangle contactor control signal KD; and when any signal is 1, a Boolean quantity with the value of 1 is sent to the reset end of the second RS trigger functional block to disconnect a main motor star-shaped contactor control signal KS, so that the main motor contactor, the main motor star-shaped contactor, the main motor triangular contactor and the cooling fan are in contact disconnection, and the compressor unit is stopped.

As shown in fig. 4, the loading process of the present invention comprises the steps of:

step S31: if the DCS controller receives an interlocking loading instruction, the DCS controller sends a loading electromagnetic valve control signal KL, a loading gas circuit is connected, and a discharging electromagnetic valve control signal KU is disconnected, wherein on the premise that a stopping instruction FS is not triggered, the air compressor starts to complete star-triangle switching for the first time, or the pressure transmitter P1 at the exhaust port is reduced to a loading threshold value and the main motor completes star-triangle switching;

As shown in fig. 7, in step S31, when the exhaust port pressure transmitter P1 determines that the exhaust port pressure is lower than the set value (e.g., 750Kpa) through the sixth HLALM high/low limit determination function block, it sends an exhaust port pressure low signal P1L with a value of 1. AND a main contactor feedback contact signal CM AND a main motor triangular contactor feedback contact CD are jointly sent to an eighth AND logic AND function block, AND when the main contactor feedback contact signal CM AND the main motor triangular contactor feedback contact CD are both 1, a main motor star-delta switching completion signal C delta with the value of 1 is sent out. AND a signal of the shutdown command FS + KT after passing through the sixth NOT logic non-functional block, the exhaust port pressure low signal P1L AND the main motor star-delta switching completion signal C delta jointly enter a tenth AND logic AND functional block. AND a feedback contact CS of the main motor star-shaped contactor is sent into a first TD _ OFF hysteresis reset type timer function block, a Boolean signal with the value of 1 second is sent out after the feedback contact CS of the main motor star-shaped contactor disappears, AND the Boolean signal, a feedback contact signal CD of the triangular contactor AND a signal of a stop command FS + KT passing through a first NOT logic non-function block enter a ninth AND logic AND function block together. AND when any input signal of the ninth AND logic AND function block AND the tenth AND logic AND function block jointly enters a ninth OR logic OR function block, an interlocking loading instruction FL with the output value of 1 is output to a first EMD1 override input pin of the second DEVICE digital manual operator function block when the input signal is 1, Boolean quantity with the output value of 1 of the output pin of the second DEVICE digital manual operator function block OUT1 is forced to be sent to a set end of a fourth RS trigger function block AND a reset end of a fifth RS trigger function block, AND a loading electromagnetic valve control signal KL is sent OUT AND a discharging electromagnetic valve control signal KU is disconnected.

Step S32: after a loading gas circuit is connected, if a DCS controller receives a loading adjustment allowing instruction FC, the DCS controller is allowed to send an electric adjusting valve control instruction VS, and the electric adjusting valve control instruction VS is used as an output variable and a controlled variable P1 to adopt a PID operation loop to realize the loading of the air compressor; where FC is FL · Δ P1 · QI · QV, i.e., the load-permit command FL exists, the exhaust port pressure transmitter P1 deviates beyond the regulation dead band, the main motor current transmitter I signal quality is good and the electrical regulator valve position feedback VZ signal quality is good.

As shown in fig. 7, in the specific implementation of step S32, the discharge port pressure transmitter P1 and the air compressor outlet pressure set value SP are sent to the first DEV deviation calculation function block, the deviation between the set value and the actual discharge pressure is calculated nonlinearly, the calculated value Y is output as the main adjustment value of the first PID calculation function block to participate in PID calculation, and finally, the electric control valve control command VS is output to realize the precise adjustment of the load output of the air compressor. In the embodiment of the present invention, the PID operation loop of the control command VS of the electric control valve may adopt a PID operation loop similar to the PID operation loop at the slow electric speed regulation stage in the patent application (publication number CN109026688A) filed by the applicant.

The position feedback VZ of the electric regulating valve is judged to be signal quality through a first TQ quality judgment function block and sent to a tenth NOT logic non-function block; the current I of the main motor is judged to be signal quality through the second TQ quality judgment functional block and is sent to the eleventh NOT logic non-functional block; the exhaust port pressure P1 and the air compressor outlet pressure set value SP are calculated and judged by the first DEV deviation operation functional block, and then an out-of-limit judgment signal (such as lower than-10 Kpa or higher than 10Kpa) is output and sent to the ninth NOT logic non-functional block; and a signal of the load permission instruction FL after passing through the seventh NOT logic non-functional block, an interlocking unload instruction signal FU output by the tenth OR logic non-functional block, an output signal of the ninth NOT logic non-functional block, an output signal of the tenth NOT logic non-functional block and an output signal of the eleventh NOT logic non-functional block jointly enter the eleventh OR logic non-functional block, and if any input signal is 1, a locking instruction is output to the locking input pin of the first PID operation functional block to lock the control function of the electric control valve.

it should be noted that good signal quality in the embodiments of the present invention means that the current signal or the pressure signal detected by the transmitter is within a set value range.

As shown in fig. 5, the unloading process of the present invention includes the following steps:

Step S41: if the DCS controller receives the interlocking unloading instruction FU, the DCS controller sends a discharge solenoid valve control signal KU to connect an unloading gas circuit and disconnect a loading solenoid valve control signal KL to realize unloading of the air compressor; wherein either the main motor has started but not completed the star-delta switch, or the vent pressure transmitter P1 rises to the unload threshold and the main motor completes the star-delta switch to begin doing work, or a shutdown command FS exists.

as shown in fig. 7, in step S41, when the exhaust port pressure transmitter P1 determines that the exhaust port pressure is higher than the unloading threshold (e.g., 830Kpa) through the sixth HLALM high/low limit determining function block, it sends a pressure high signal P1H with a value of 1, AND the signal C Δ of completing the star-delta switching of the main motor enters the eleventh AND logic AND function block together. AND a feedback contact signal CM of the main contactor, a feedback contact signal CD of the triangular contactor after passing through the eighth NOT logic non-functional block AND a feedback contact signal CS of the star contactor enter a twelfth AND logic AND functional block together. The output signal of the eleventh AND logic AND function block, the output signal of the twelfth AND logic AND function block AND the shutdown command FS + KT enter the tenth OR logic OR function block together, any input signal of the tenth OR logic OR function block is 1, the interlocking unloading command FU with the value of 1 is output to the override input pin of the second DEVICE digital manual operator function block EMD2, Boolean quantity with the output value of 1 of the output pin of the second DEVICE digital manual operator function block OUT2 is forced to be sent to the reset end of the fourth RS trigger function block AND the set end of the fifth RS trigger function block, the control signal KU of the opening AND discharging electromagnetic valve is sent OUT, AND the control signal KL of the loading electromagnetic valve is disconnected.

according to the energy-saving air compressor control system based on DCS comprehensive control, the running state of the compressor set is monitored by installing the signal collector group on the compressor set; the DCS controller is adopted to periodically scan the signal collector group so as to obtain the current running state of the compressor unit in real time, and a corresponding DCS control strategy is formulated, so that the compressor unit can switch the working procedures of running starting, loading, unloading, stopping and the like according to the working conditions, the running of the compressor unit is more reasonable, and the running energy consumption of the compressor unit can be reduced; meanwhile, data obtained by scanning of the DCS controller can be stored in a DCS historical database, so that the historical working condition of the equipment in any period of the whole life cycle can be read back, and the requirements of fault analysis and equipment optimization are fully met.

when the energy-saving modification of the existing air compressor system is carried out, according to the structural schematic diagram of the energy-saving air compressor control system based on the DCS comprehensive control shown in the figure 1, the existing air compressor system is modified, the electric control system of the existing air compressor system is removed to replace the electric unit and the signal collector group provided by the embodiment of the invention, so that the electric unit is connected with the output module of the DCS control unit, the signal collector group is connected with the input module of the DCS control unit, and the output module and the input module are electrically connected with the DCS controller through signal cables; and change the partial structure of air compressor machine system, if change the pressure sensor that current air compressor machine system generally adopted for standard pressure transmitter, will hold the accent valve, shuttle valve and change for electrical control valve, pneumatic valve etc. above-mentioned transformation need not to change the main part of current air compressor machine system, consequently can greatly reduce the cost of energy-conserving transformation.

In order to further verify the actual energy-saving effect of the energy-saving air compressor control system and method based on DCS comprehensive control provided by the invention, the practical tests are carried out in company A: an air compressor station formed by 4 air compressors of company A is improved, and the air compressor of company A is a screw compressor of SA-185W/0.85 type of Kanshiza, Guangdong; the company A has an industrial DCS control system consisting of GE Xinhua OCE6000 type controllers, and one set of control units are selected as DCS control units; the logic function blocks of the control module and the configuration software language adopted by each DCS strategy in the DCS control unit are all universal, the method can be realized by increasing, decreasing and replacing logic function blocks of similar control modules and configuration software languages in other domestic and foreign brand types of DCS systems, the implementation cost is 35 ten thousand yuan in total, after 2 months of continuous operation, electricity is saved by 648 degrees every day, the accumulated recovery cost is 1.9 ten thousand yuan, all the modification cost can be recovered within 3 years, the stable operation period of the modified equipment is estimated to be about 10 years, and the energy-saving benefit is extremely obvious.

although terms such as air compressor, DCS, sensors, pressure transducers, electrically operated regulator valves, pneumatic valves, chiller solenoid valves, oil and gas barrel separators are used more often herein, the possibility of using other terms is not excluded. These terms are used merely to more conveniently describe and explain the nature of the present invention; they are to be construed as being without limitation to any additional limitations that may be imposed by the spirit of the present invention.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims (10)

1. The utility model provides an energy-saving air compressor control system based on DCS comprehensive control which characterized in that: the system comprises a compressor unit, an electrical unit, a signal collector group and a DCS control unit; the signal collector group is used for monitoring the running states of the electrical unit and the compressor unit; the DCS control unit sends out different control instructions according to the information fed back by the signal collector group; and the electrical unit controls the compressor unit to start, load, unload or stop according to the instruction sent by the DCS control unit.

2. The energy-saving air compressor control system based on DCS overall control of claim 1, characterized in that: the compressor unit comprises an air filter, an electric regulating valve, a pneumatic valve, a compressor, an oil-gas barrel separator, an oil filter, a cooler and an outlet screwing valve; the air filter, the electric regulating valve, the pneumatic valve, the compressor, the oil-gas barrel separator cooler, the outlet screwing valve and the compressed gas main pipe are sequentially connected to form a compressed gas circuit; the top of the oil-gas barrel separator is connected to the front of the pneumatic valve through a discharge solenoid valve to form a discharge gas path; and an outlet pipe of the oil-gas barrel separator is connected to a driving cylinder of the pneumatic valve through a loading electromagnetic valve to form a loading gas circuit.

3. The energy-saving air compressor control system based on DCS overall control of claim 2, characterized in that: the electric unit comprises a power supply end, an emergency stop button, a main motor contactor, a main motor star-shaped contactor and a main motor triangular contactor, wherein the main motor contactor, the main motor star-shaped contactor and the main motor triangular contactor are used for controlling the power supply of the compressor motor, a cooling fan contactor is used for controlling the power supply of the cooling fan motor, and three electric branches are respectively used for controlling the power supply of the electric regulating valve, the release electromagnetic valve and the loading electromagnetic valve.

4. The energy-saving air compressor control system based on DCS overall control of claim 1, characterized in that: the signal acquisition device group comprises but is not limited to an air filter differential pressure switch PS1, a main motor temperature switch TS, a main motor current transmitter I, a thermocouple relay TH, a phase sequence protector PH, an oil filter differential pressure switch PS2, a separator pressure transmitter P3, a separator temperature sensor T2, an exhaust port temperature sensor T1, an exhaust port pressure transmitter P1, a closed water pressure transmitter P4, a compressed air main pipe pressure transmitter P2, an electric regulating valve position feedback VZ, a main motor contactor feedback contact CM, a main motor star-shaped contactor feedback contact CS, a main motor triangle-shaped contactor feedback contact CD, a cooling fan contactor feedback contact CF and an emergency stop button feedback contact CE.

5. The energy-saving air compressor control system based on DCS overall control of claim 1, characterized in that: the DCS unit comprises a DCS controller, an input module, an output module and a human-computer interface; the human-computer interface comprises but is not limited to a starting control signal input interface, a stopping control signal input interface, an electric control valve control instruction input interface and a display interface.

6. an energy-saving air compressor control method based on DCS overall control is applied to the energy-saving air compressor control system based on DCS overall control according to any one of claims 1-5; the method is characterized in that: the method comprises the following steps:

and the DCS controller scans the signal collector group in real time and controls the compressor unit to enter a starting process, a loading process, an unloading process or a stopping process according to data fed back by the signal collector group.

7. The DCS comprehensive control-based energy-saving air compressor control method of claim 6, wherein the method comprises the following steps: the starting procedure comprises the following steps:

Step S11: if the DCS controller receives an interlocking starting instruction FR or a starting control signal KR, the DCS controller sends a main motor contactor control signal KM, a main motor star-shaped contactor control signal KS and a cooling fan contact control signal KF, so that a main motor, a main motor star-shaped loop and a cooling fan motor are started; the interlocking starting instruction is that the deviation of a compressed gas main pipe pressure transmitter P2 is lower than a set value, the PH of a main motor phase sequence protector, a thermocouple relay TH and a temperature switch TS are not closed, and the disconnection time of a feedback contact CM of a main contactor meets the set value;

step S12: after the main motor star-shaped loop is started, if the DCS controller receives a main motor loop switching permission instruction F delta, the DCS controller sends a main motor triangle contactor control signal KD, disconnects a main motor star-shaped contactor control signal KS, and switches the main motor star-shaped loop into a triangle loop to complete the starting of the compressor unit; the phase sequence protector PH, the thermocouple relay TH and the main motor temperature switch TS are not actuated, the closing time of the main contactor feedback contact CM and the star contactor feedback contact CS meets the set value, and the signal quality of the main motor current transmitter I is good.

8. The DCS comprehensive control-based energy-saving air compressor control method of claim 6, wherein the method comprises the following steps: the shutdown process comprises the following steps:

step S21: if the DCS controller receives an electric protection shutdown loop instruction FSE, a thermal protection shutdown loop instruction FST or an automatic shutdown loop instruction FSA, the DCS controller sends an unloading instruction, a locking loading instruction and a locking output adjusting instruction, and disconnects a main motor contactor control signal KM, a main motor star-shaped contactor control signal KS, a main motor triangle-shaped contactor control signal KD and a cooling fan contact control signal KF to complete shutdown of the compressor unit; wherein, the FSE is TH + CE + PH + TS, namely at least one action of the thermocouple relay TH, the emergency stop button feedback contact CE, the phase sequence protector PH and the main motor temperature switch TS; FST-OT 1+ OP1, i.e. the exhaust port temperature sensor T1 exceeds the shutdown protection set point, or the exhaust port pressure transmitter P1 exceeds the shutdown protection set point; namely, the closing time of the control signal of the bleed-off electromagnetic valve meets the set value and the deviation of the pressure transmitter P2 of the compressed air main pipe is not lower than the set value;

Or when the DCS controller receives the stop control signal KT, the DCS controller sends an unloading instruction, continuously unloads and locks loading and output regulation, and when the pressure transmitter P3 of the separator is lower than a set value or the continuous on-time of the control signal KU of the discharge solenoid valve reaches the set value, the control signal KM of the main motor contactor, the control signal KS of the main motor star-shaped contactor, the control signal KD of the main motor triangle-shaped contactor and the contact control signal KF of the cooling fan are disconnected, so that the compressor unit is stopped.

9. the DCS comprehensive control-based energy-saving air compressor control method of claim 6, wherein the method comprises the following steps: the loading process comprises the following steps:

Step S31: if the DCS controller receives a loading permission instruction FL, the DCS controller sends a loading electromagnetic valve control signal KL to connect a loading gas circuit and disconnect a discharge electromagnetic valve control signal KU, wherein on the premise that a stop instruction FS is not triggered, the air compressor starts to complete the star-delta switching for the first time, or the pressure transmitter P1 at the exhaust port is reduced to a loading threshold value and the main motor completes the star-delta switching;

Step S32: after a loading gas circuit is connected, if a DCS controller receives a loading adjustment permission instruction FC, the DCS controller is allowed to send an electric adjusting valve control instruction VS, and the electric adjusting valve control instruction VS is used as an output variable and a controlled variable P1 to adopt a PID operation loop to realize the loading adjustment of the air compressor; where FC is FL · Δ P1 · QI · QV, i.e., the load-permit command FL exists, the exhaust port pressure transmitter P1 deviates beyond the regulation dead band, the main motor current transmitter I signal quality is good and the electrical regulator valve position feedback VZ signal quality is good.

10. the DCS comprehensive control-based energy-saving air compressor control method of claim 6, wherein the method comprises the following steps: the unloading process comprises the following steps:

Step S41: if the DCS controller receives the interlocking unloading instruction FU, the DCS controller sends a discharge solenoid valve control signal KU to connect an unloading gas circuit and disconnect a loading solenoid valve control signal KL to realize unloading of the air compressor; wherein either the main motor has started but not completed the star-delta switch, or the vent pressure transmitter P1 rises to the unload threshold and the main motor completes the star-delta switch to begin doing work, or a shutdown command FS exists.