A method for coordinated control of double unit steam turbine generator and pressure of cylinder based on DCS system

Abstract

A kind of double-unit steam turbine generator and split cylinder pressure coordinated control method based on DCS system, comprising the following steps: step 1: system real-time acquisition of extraction back steam turbine steam turbine generator inlet pressure, condensing steam turbine steam turbine generator inlet pressure, split cylinder pressure, extraction back steam turbine unit power generation and condensing steam turbine unit power generation, the present application relates to the field of control system, specifically to a kind of double-unit steam turbine generator and split cylinder pressure coordinated control method based on DCS system.The present application has the advantages that: using the present technology, makes power generation system realize self-control adjustment, without manual operation under the condition that split cylinder external steam supply is disturbed, and the self-control system can be adjusted smoothly.

Description

Technical Field

[0001] This invention relates to the field of control systems, and more specifically to a method for coordinated control of the pressure of a dual-unit steam turbine generator and a steam distribution cylinder based on a DCS system. Background Technology

[0002] Currently, traditional sulfuric acid plant steam systems rely on manual operation of the DCS interface to adjust power generation load, which has the following problems: Response delay: Manual operation response time exceeds 30 seconds, making it unable to adapt to rapid load changes; Low control accuracy: Pressure fluctuation range of the distribution cylinder reaches ±0.1MPa, leading to instability in downstream production; Energy waste: Vent valve operates more than 5,000 times per year, resulting in a steam loss of approximately 1,800 tons per year.

[0003] Currently, there are several issues: multi-variable coupling: pressure, power, and power factor influence each other, making it difficult for a single PID loop to coordinate; lack of adaptive strategies: load sharing between dual units relies on experience and cannot be dynamically optimized; accelerated equipment aging: frequent pressure fluctuations lead to pipeline fatigue and increased maintenance costs. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned shortcomings by providing a subject name.

[0005] This invention includes the following steps:

[0006] Step 1: The system collects real-time data on the steam inlet pressure of the turbine generator in the extraction-back steam turbine, the steam inlet pressure of the turbine generator in the condensing steam turbine, and the pressure of the steam distribution cylinder. Power generation of the back-draft steam turbine unit and the power generation of condensing steam turbine units ;

[0007] Step 2: Based on the pressure deviation of the distribution cylinder =Cylinder pressure setting value - Actual value of cylinder pressure A cascaded PID controller is used to calculate the load demand increment. And set upper and lower control limits for the generator steam intake and power generation load according to demand;

[0008] Step 3: Pressure deviation of the cylinder If the actual pressure is less than 0, the actual pressure value is greater than the set value, the pressure of the distribution cylinder increases, which means that the downstream unit steam consumption decreases. At this time, the PID controller automatically reduces the set value of the steam inlet pressure of the condensing steam turbine generator, and the power generation load of the condensing steam turbine increases.

[0009] Step 4: When the setpoint of the condensing steam turbine inlet pressure drops to the lower limit of 0.82, the condensing steam turbine is operating at full load.

[0010] Step 5: When the condensing steam turbine is operating at full load, if the pressure in the distribution cylinder no longer continues to rise, the power generation load of the condensing steam turbine will remain unchanged.

[0011] Step 6: When the condensing steam turbine is working at full load, if the pressure of the distribution cylinder shows a downward trend, the set value of the condensing steam turbine inlet steam pressure will be automatically increased by the PID controller. By reducing the power generation of the condensing steam turbine, the pressure of the distribution cylinder will be stabilized to 0.85 MPa.

[0012] Step 7: When the condensing steam turbine is working at full load, if the pressure in the distribution cylinder continues to rise and reaches 0.87 MPa, the PID controller will automatically increase the set value of the steam inlet pressure of the extraction back steam turbine, thereby reducing the power generation load of the extraction back steam turbine and reducing the amount of steam supplied to the distribution cylinder and the condensing steam turbine generator.

[0013] Step 8: After completing Step 7, if the pressure of the distribution cylinder begins to decrease, the PID controller will automatically prioritize reducing the pressure setpoint of the extraction-back turbine. When the pressure setpoint of the extraction-back turbine is reduced to the lower limit, the steam inlet pressure setpoint of the condensing turbine will be automatically reduced by the PID controller.

[0014] Step 9: The above control is based on a dynamic priority strategy, which allocates the load increments of the extraction-backflow turbine and the condensing turbine through the high-selection module. and The calculation formula is:

[0015]

[0016]

[0017]

[0018]

[0019] ;

[0020] Step 10: The load increment is compared with the current real-time power generation load through the pulse positioner function block. When the measured value is less than the set value, a positive output pulse is generated; when the measured value is greater than the set value, a reverse output pulse is generated. The pulse width, forward and reverse stroke rate, deviation dead zone, and output pulse period are set according to the internal parameters of the function.

[0021] Step 11: When the intermediate-pressure inlet steam pressure of the extraction-back steam turbine is higher than 3.5 MPa or the low-pressure inlet steam pressure of the condensing steam turbine is higher than 0.89 MPa, activate the vent valve control logic and adjust the opening degree. With overpressure value Positive correlation, the calculation formula is:

[0022]

[0023]

[0024]

[0025] The proportional gain of the medium-pressure venting control loop is Kp=14.29 and Ki=120s;

[0026] The proportional gain of the low-pressure venting control loop is Kp=6.67, and Ki=120s.

[0027] Step 12: Synchronize historical and real-time data through the DCS system to optimize control commands.

[0028] A condensing steam turbine has a full load capacity of 7300-7500KW.

[0029] The DCS system collects real-time data on the steam inlet pressure of the turbine generator in the extraction-back steam turbine, the steam inlet pressure of the turbine generator in the condensing steam turbine, and the pressure of the steam distribution cylinder. Power generation of the back-draft steam turbine unit and the power generation capacity of condensing steam turbine units, .

[0030] The DCS also collects data on the operation of the steam turbine generators of the extraction-back steam turbine and condensing steam turbine when they are put into automatic mode, and collects real-time data on the reactive power, voltage, current, power factor, and cylinder temperature of the steam turbine generators.

[0031] The advantages of this invention are: by using this technology, the power generation system can achieve automatic control and regulation. When the external steam supply to the steam distribution cylinder is disturbed, no manual operation is required and the automatic control system can regulate smoothly.

[0032] 1. The pressure fluctuation of the main steam valve was reduced from ±0.1 MPa to ±0.02 MPa, and the pressure control accuracy of the distribution cylinder was improved by 80%;

[0033] 2. The generator set load distribution efficiency is improved by 12%, and the vent valve operating frequency is reduced by 100%;

[0034] 3. Annual steam loss is reduced by 1,800 tons. At 250 yuan per ton of steam, the economic benefit is increased by 450,000 yuan, and the need for manual intervention is reduced by more than 95%.

[0035] 4. The number of people in the power generation position has been reduced from 4 to 1, saving 300,000 yuan in costs annually;

[0036] 5. Improve the safety and stability of generator set operation. Attached Figure Description

[0037] Figure 1 This is a schematic diagram of the process of this invention.

[0038] Figure 2 This is a schematic diagram of the structure of the present invention.

[0039] Figure 3 It refers to the direction of active power signal flow controlled by the DCS.

[0040] Figure 4 It is the DCS that controls the flow of reactive power signals.

[0041] Figure 5 This is a basic control logic block diagram of a DCS.

[0042] Figure 6 This is the generator power factor control logic diagram.

[0043] Figure 7 This is a logic diagram for the cascaded pressure control of the cylinder / vent valve.

[0044] Figure 8 This is a control logic diagram for steam venting via a high-pressure venting valve in the pipeline network.

[0045] Figure 9 It refers to the control of cylinder pressure before and after operation.

[0046] Figure 10 It refers to the control of the inlet steam pressure before and after the generator of the extraction-back steam turbine.

[0047] Figure 11 It refers to the control status of the inlet steam pressure before and after the condensing steam turbine generator.

[0048] Figure 12 These are status monitoring panels for two generator sets.

[0049] Figure 13 This is the situation where the vent valve automatically vents when the pipeline pressure exceeds the limit. Detailed Implementation

[0050] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0051] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0052] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0053] In the description of the embodiments of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use, they are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. Furthermore, if terms such as "first" or "second" appear in the description of this invention, they are only used to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0054] In the description of the embodiments of the present invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set" and "connection" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0055] As shown in the figure, the present invention includes the following steps:

[0056] Step 1: The system collects real-time data on the steam inlet pressure of the turbine generator in the extraction-back steam turbine, the steam inlet pressure of the turbine generator in the condensing steam turbine, and the pressure of the steam distribution cylinder. Power generation of the back-draft steam turbine unit and the power generation of condensing steam turbine units ;

[0057] Step 2: Based on the pressure deviation of the distribution cylinder =Cylinder pressure setting value - Actual value of cylinder pressure A cascaded PID controller is used to calculate the load demand increment. And set upper and lower control limits for the generator steam intake and power generation load according to demand;

[0058] Step 3: Pressure deviation of the cylinder If the actual pressure is less than 0, the actual pressure value is greater than the set value, the pressure of the distribution cylinder increases, which means that the downstream unit steam consumption decreases. At this time, the PID controller automatically reduces the set value of the steam inlet pressure of the condensing steam turbine generator, and the power generation load of the condensing steam turbine increases.

[0059] Step 4: When the setpoint of the condensing steam turbine inlet pressure drops to the lower limit of 0.82, the condensing steam turbine is operating at full load.

[0060] Step 5: When the condensing steam turbine is operating at full load, if the pressure in the distribution cylinder no longer continues to rise, the power generation load of the condensing steam turbine will remain unchanged.

[0061] Step 6: When the condensing steam turbine is working at full load, if the pressure of the distribution cylinder shows a downward trend, the set value of the condensing steam turbine inlet steam pressure will be automatically increased by the PID controller. By reducing the power generation of the condensing steam turbine, the pressure of the distribution cylinder will be stabilized to 0.85 MPa.

[0062] Step 7: When the condensing steam turbine is working at full load, if the pressure in the distribution cylinder continues to rise and reaches 0.87 MPa, the PID controller will automatically increase the set value of the steam inlet pressure of the extraction back steam turbine, thereby reducing the power generation load of the extraction back steam turbine and reducing the amount of steam supplied to the distribution cylinder and the condensing steam turbine generator.

[0063] Step 8: After completing Step 7, if the pressure of the distribution cylinder begins to decrease, the PID controller will automatically prioritize reducing the pressure setpoint of the extraction-back turbine. When the pressure setpoint of the extraction-back turbine is reduced to the lower limit, the steam inlet pressure setpoint of the condensing turbine will be automatically reduced by the PID controller.

[0064] Step 9: The above control is based on a dynamic priority strategy, which allocates the load increments of the extraction-backflow turbine and the condensing turbine through the high-selection module. and The calculation formula is:

[0065]

[0066]

[0067]

[0068]

[0069] ;

[0070] Step 10: The load increment is compared with the current real-time power generation load through the pulse positioner function block. When the measured value is less than the set value, a positive output pulse is generated; when the measured value is greater than the set value, a reverse output pulse is generated. The pulse width, forward and reverse stroke rate, deviation dead zone, and output pulse period are set according to the internal parameters of the function.

[0071] Step 11: When the intermediate-pressure inlet steam pressure of the extraction-back steam turbine is higher than 3.5 MPa or the low-pressure inlet steam pressure of the condensing steam turbine is higher than 0.89 MPa, activate the vent valve control logic and adjust the opening degree. With overpressure value Positive correlation, the calculation formula is:

[0072]

[0073]

[0074]

[0075] The proportional gain of the medium-pressure venting control loop is Kp=14.29 and Ki=120s;

[0076] The proportional gain of the low-pressure venting control loop is Kp=6.67, and Ki=120s.

[0077] Step 12: Synchronize historical and real-time data through the DCS system to optimize control commands.

[0078] A condensing steam turbine has a full load capacity of 7300-7500KW.

[0079] The DCS system collects real-time data on the steam inlet pressure of the turbine generator in the extraction-back steam turbine, the steam inlet pressure of the turbine generator in the condensing steam turbine, and the pressure of the steam distribution cylinder. Power generation of the back-draft steam turbine unit and the power generation capacity of condensing steam turbine units, .

[0080] The DCS also collects data on the operation of the steam turbine generators of the extraction-back steam turbine and condensing steam turbine when they are put into automatic mode, and collects real-time data on the reactive power, voltage, current, power factor, and cylinder temperature of the steam turbine generators.

[0081] The hardware components include a DCS system (containing a PID module, handheld controller module, high / low selection logic module, pulse module, and filter module); a data acquisition and communication module (generator inlet steam pressure, cylinder pressure, temperature sensors, generator power, and power factor); and actuators (turbine governor, excitation system, steam regulating valve, and vent valve). It also includes real-time generator data (terminal voltage, current, active power, reactive power, power factor, etc.) transmitted to the DCS database via the Modbus protocol, allowing operators to monitor the generator set's operation online.

[0082] Basic control layer of control method (main steam valve pressure - power generation regulation):

[0083] Active power closed-loop control: Generator inlet steam pressure → PID control → active power calculation value → based on the deviation between the calculated value and the actual value → if the deviation exceeds the dead zone setpoint → send pulse signal → adjust generator load.

[0084]

[0085] ;

[0086] This indicates the deviation between the set value and the actual value of the steam turbine generator inlet pressure.

[0087] Where Kp=1.25, Ki=0.1, Kd=0

[0088] Hard limiting protection for power generation:

[0089] Back-extraction steam turbine unit: 1000KW≤ ≤5420KW;

[0090] Condensing steam turbine unit: 2500KW≤ ≤7500KW;

[0091] Power factor adaptive control:

[0092] Handheld controller module → Deviation between power factor setting and current value → Pulse signal → Dynamically adjust reactive power.

[0093] like Figure 4 As shown, the main function of the Pulse Positioner (PULPOS) function block is to compare two analog input signals, namely the setpoint and the feedback value (measured value) of the process parameter, and generate two BOOL type outputs based on the comparison result. When the measured value is less than the setpoint, a positive output pulse is generated; when the measured value is greater than the setpoint, a negative output pulse is generated. (When writing the program, it is also necessary to modify the internal parameters of the PID function block according to the generator load of the two generators of the extraction-back steam turbine and the condensing steam turbine, and the pressure setpoint before the main steam valve. At the same time, when the program is put into testing, pay attention to the changes in the generator current and voltage values, and make a program switching switch. If the test effect is not good, immediately disconnect the automatic control and restore the manual control.)

[0094] Collaborative optimization layer (cylinder pressure-unit priority control):

[0095] Cascade control loop:

[0096] Main circuit: cylinder pressure → PID → dynamically generate main steam valve pressure setpoint for extraction-back steam turbine / condensing steam turbine;

[0097] Secondary loop: Main steam valve pressure of extraction-back steam turbine / condensing steam turbine → PID → active power calculation value.

[0098] Dynamic priority strategy

[0099] When the pressure in the distribution cylinder is too high, the high-pressure selection module prioritizes reducing the pressure setpoint of the condensing steam turbine:

[0100] The pressure setting value of the main steam valve of the condensing steam turbine is reduced first by the high-selection module → the power generation of the condensing steam turbine is increased → after reaching the upper limit of power generation, the pressure setting value of the main steam valve of the extraction back steam turbine is reduced → if the pressure is still over the limit at this time, the vent valve is activated to vent.

[0101] When the pressure in the distribution cylinder is insufficient, the low-selection module prioritizes reducing the pressure setpoint of the back-extraction steam turbine:

[0102] The module is selected to lower the pressure of the extraction back steam turbine first, then the extraction back steam turbine supplies more steam, then the pressure of the condensing steam turbine is increased in conjunction with the module, then the condensing steam turbine generates less electricity, and then the multi-directional steam distribution cylinder supplies steam.

[0103] Prioritizing full-load power generation of condensing steam turbines is crucial for maximizing the plant's overall power generation economy. Condensing turbines have a narrow efficiency range: their thermal efficiency is highest at rated load (e.g., 7500 kW) (reaching 35%~40%), but drops sharply at partial load (e.g., efficiency may decrease to 25% at 50% load). If condensing steam turbines are not operating at full capacity, the plant's coal consumption for power generation will increase significantly.

[0104] Adjustment and compensation capability of extraction-back turbine units: Extraction-back turbines can flexibly balance the pressure of the distribution cylinder by adjusting the extraction steam volume, and the adjustment of its power generation load has little impact on the overall efficiency (because heating demand takes priority).

[0105] like Figure 10 As shown, the control status of the inlet steam pressure of the extraction-back steam turbine generator before and after (when the condensing steam turbine is fully loaded to 7500KW, the inlet steam pressure setting of the extraction-back steam turbine is automatically modified):

[0106] like Figure 11 As shown, the control status of the steam inlet pressure of the condensing steam turbine generator before and after (the pressure of the distribution cylinder is stabilized by automatically modifying the steam inlet pressure setpoint of the condensing steam turbine):

[0107] like Figure 12 As shown, the status monitoring panels for the two generator sets: monitoring the condensing steam turbine (corresponding to the lower...) Figure 7 #Generator), pullback steam turbine (corresponding below) Figure 5 #Generator) Real-time status of generator voltage and current under automatic control.

[0108] like Figure 13 As shown, when the pipeline pressure exceeds the limit, the vent valve automatically vents. Because the pressure control of the distribution cylinder is stable, the steam is always vented at zero.

[0109] Implementation

[0110] 1. Parameter Configuration

[0111] PID controller parameters:

[0112] Condensing steam turbine main circuit 800 300 0 condensing steam turbine auxiliary circuit 5 45 0 Main circuit of a back-extraction steam turbine 80 450 0 Auxiliary circuit of a back-extraction steam turbine 20 300 0

[0113] Because DCS systems come from different brands, PID controllers input either proportional band (Pb) or proportional gain (Kp) according to actual needs; the conversion formula between the two is Pb=100 / Kp.

[0114] Steam turbine generator amplitude limit:

[0115] The main steam valve pressure of the extraction-back steam turbine is 3.05~3.2MPa, and the power generation capacity is 1000KW≤extraction-back steam turbine≤5420KW;

[0116] The main steam valve pressure of the condensing steam turbine is 0.82~0.86MPa, and the power generation capacity is 2500KW≤condensing steam turbine≤7500KW;

[0117] Pulse Positioner Function Block (PULPOS) Internal Parameters:

[0118] Active power of condensing steam turbine 160 160 80 10s Condensing steam turbine power factor 0.06 0.06 0.03 10s Active power of back-extraction steam turbine 100 100 50 10s Power factor of a back-draft steam turbine 0.12 0.12 0.05 20s

[0119] In each pulse cycle, this function block TCYC outputs a positive pulse and a negative pulse based on the comparison result between the deviation and the dead zone DB. If the deviation EI is within the dead zone range [-DB, DB], there is no pulse output signal.

[0120] If EI > DB, a positive pulse is generated. Pulse width = (SV - PV) / FSR = EI / FSR seconds; where SV is the set value; PV is the measured value; and FSR is the positive stroke rate.

[0121] If EI < -DB, a reverse pulse is generated. Pulse width = (PV - SV) / ​​RSR = -EI / RSR seconds; where SV is the set value; PV is the measured value; and RSR is the reverse travel rate.

[0122] 2. Typical Control Scenarios

[0123] Scenario 1: Over-limit adjustment of cylinder pressure

[0124] Input condition: cylinder pressure =0.90MPa;

[0125] Controlling actions:

[0126] 1. Reduce the pressure setpoint of the condensing steam turbine to 0.82 MPa, and increase the power generation to 7.5 MW;

[0127] 2. If the pressure does not drop, reduce the pressure setpoint of the extraction-back turbine to 3.20 MPa;

[0128] 3. If the pipeline steam pressure is higher than 0.87 MPa, start the vent valve and adjust the opening degree according to the PID.

[0129] Result: Pressure recovered to 0.85 MPa.

[0130] Scenario 2: Compensation for insufficient pressure in the distribution cylinder

[0131] When the pressure in the distribution cylinder gradually decreases from 0.87 MPa;

[0132] The main circuit lowers the pressure setpoint of the extraction-back turbine to 3.05 MPa to increase the steam supply flow rate;

[0133] The pressure setpoint of the condensing steam turbine is gradually increased from 0.82MPa to 0.87MPa, and the power generation of the condensing steam turbine is automatically reduced until the pressure index of the distribution cylinder is stabilized at 0.85MPa.

[0134] 3. Protection Mechanism

[0135] Mode switching: When automatic control fails, switch to manual mode and trigger an alarm;

[0136] Pulse fault tolerance: If there is no response after 3 consecutive pulses, the actuator is determined to be faulty and the shutdown protection is activated.

Claims

1. A method for coordinating the pressure of a dual-unit steam turbine generator and a distribution cylinder based on DCS, characterized in that... Includes the following steps: Step 1: The system collects real-time data on the inlet steam pressure of the turbine generator in the extraction-back steam turbine, the inlet steam pressure of the turbine generator in the condensing steam turbine, the pressure of the steam distribution cylinder, and the power generation of the extraction-back steam turbine unit. and the power generation of condensing steam turbine units ; Step 2: Based on the pressure deviation of the distribution cylinder =Cylinder pressure setting value - Actual value of cylinder pressure A cascaded PID controller is used to calculate the load demand increment. And set upper and lower control limits for the generator steam intake and power generation load according to demand; Step 3: Pressure deviation of the cylinder If the actual pressure value is less than 0, the actual pressure value is greater than the set value, the pressure of the distribution cylinder increases, which means that the downstream unit steam consumption decreases. At this time, the PID controller automatically reduces the set value of the steam inlet pressure of the condensing steam turbine generator, and the power generation load of the condensing steam turbine increases. Step 4: When the setpoint of the condensing steam turbine inlet pressure drops to the lower limit of 0.82, the condensing steam turbine is operating at full load. Step 5: When the condensing steam turbine is operating at full load, if the pressure in the distribution cylinder no longer continues to rise, the power generation load of the condensing steam turbine will remain unchanged. Step 6: When the condensing steam turbine is working at full load, if the pressure of the distribution cylinder shows a downward trend, the set value of the condensing steam turbine inlet steam pressure will be automatically increased by the PID controller. By reducing the power generation of the condensing steam turbine, the pressure of the distribution cylinder will be stabilized to 0.85 MPa. Step 7: When the condensing steam turbine is working at full load, if the pressure in the distribution cylinder continues to rise and reaches 0.87 MPa, the PID controller will automatically increase the set value of the steam inlet pressure of the extraction back steam turbine, thereby reducing the power generation load of the extraction back steam turbine and reducing the amount of steam supplied to the distribution cylinder and the condensing steam turbine generator. Step 8: After completing Step 7, if the pressure of the distribution cylinder begins to decrease, the PID controller will automatically prioritize reducing the pressure setpoint of the extraction-back turbine. When the pressure setpoint of the extraction-back turbine is reduced to the lower limit, the steam inlet pressure setpoint of the condensing turbine will be automatically reduced by the PID controller. Step 9: Based on the dynamic priority strategy, allocate the load increments of the extraction-backflow turbine and the condensing turbine through the high-selection module. and The calculation formula is: ； ； ； ； ； Step 10: The load increment is compared with the current real-time power generation load through the pulse positioner function block. When the measured value is less than the set value, a positive output pulse is generated; when the measured value is greater than the set value, a reverse output pulse is generated. The pulse width, forward and reverse stroke rate, deviation dead zone, and output pulse period are set according to the internal parameters of the function.

2. The method for coordinating the pressure of a dual-unit steam turbine generator and a distribution cylinder based on DCS according to claim 1, characterized in that, Step 11: When the intermediate-pressure inlet steam pressure of the extraction-back steam turbine is higher than 3.5 MPa or the low-pressure inlet steam pressure of the condensing steam turbine is higher than 0.89 MPa, activate the vent valve control logic. and Positive correlation, the calculation formula is: ； ； ； The proportional gain of the medium-pressure venting control loop is Kp=14.29 and Ki=120s; The proportional gain of the low-pressure venting control loop is Kp=6.67, and Ki=120s.

3. The method for coordinating the pressure of a dual-unit steam turbine generator and a distribution cylinder based on DCS according to claim 1, characterized in that, Step 12: Synchronize historical and real-time data through the DCS system to optimize control commands.

4. The method for coordinating the pressure of a dual-unit steam turbine generator and a distribution cylinder based on DCS according to claim 1, characterized in that, A condensing steam turbine has a full load capacity of 7300-7500KW.

5. The method for coordinating the pressure of a dual-unit steam turbine generator and a distribution cylinder based on DCS according to claim 1, characterized in that, The DCS also collects data on the operation of the steam turbine generators of the extraction-back steam turbine and condensing steam turbine when they are put into automatic mode, and collects real-time data on the reactive power, voltage, current, power factor, and cylinder temperature of the steam turbine generators.

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