Three-unit generator splitting process control system, method, equipment and medium

Abstract

The invention belongs to the technical field of petrochemical power generation, and particularly relates to a three-unit generator splitting process control system, method and equipment and a medium. According to the system, a DI unit detects a splitting signal and transmits the splitting signal to a PLC, the PLC starts a splitting process control program, a steam turbine real-time rotating speed value transmitted by an AI unit is received to calculate and dynamically output proportional adjusting parameters to a PID controller, the PID controller internally calculates and outputs a valve position signal to a servo system of a steam turbine main adjusting valve through an AO unit, and the steam turbine main adjusting valve is controlled by the PLC. The rotating speed of the turbine is finally reduced; according to the three-unit generator splitting process control method, splitting process control is achieved through the system. The equipment and the medium are used for storing computer programs, and when the programs are executed, the process control system is split; according to the method, the whole unit bumping caused by generator splitting can be effectively avoided, and the rotating speed of the steam turbine is stably controlled at the target rotating speed.

Description

Technical Field

[0001] The invention relates to the technical field of petrochemical power generation, and in particular to a control system, method, equipment and medium for a three-unit generator decoupling process. Background Art

[0002] Petrochemical power generation can not only improve energy utilization efficiency, but also reduce environmental pollution and achieve sustainable development by recovering excess heat generated in the industrial production process and converting it into electricity. The petrochemical field generally recovers a large amount of heat generated by the production process through boilers, generates steam and sends it to the steam turbine, drives the steam turbine to rotate and drives the axial flow fan to rotate to provide the required air volume for process production, forming an effective and stable energy recovery device, and uses the excess energy to drive the generator set to generate electricity through grid connection, which not only greatly reduces the user's project construction investment, but also helps users to achieve overall process configuration optimization and energy efficiency optimization of different chemical plants, and create high-quality development of the entire production process of the industrial park and carbon emission reduction; the three-unit device (hereinafter referred to as the three-unit) includes a steam turbine, an axial flow fan and a generator. It mainly relies on the steam turbine to drive the axial flow fan to rotate to achieve continuous and stable air supply to the reactor. The generator plays an auxiliary role, and the excess energy of the steam turbine is used for grid-connected power generation.

[0003] Decoupling refers to the technical measure of cutting off the connection between the generator and other parts of the power system and dividing them into two independent and unconnected parts when the synchronization between them is lost and cannot be restored. It is an important measure to maintain the stable operation of the power system and prevent the expansion of accidents and cause serious consequences. When the generator in the three units needs to be withdrawn from the power grid due to various factors, especially when the generator is withdrawn from the power grid due to fault interlocking, the power output of the steam turbine to the generator is very large. The sudden decoupling of the generator may cause the entire three units to overspeed due to a sudden drop in load. At this time, the three units are very likely to execute the shutdown interlock value due to the overspeed safety setting, which directly causes the unit to jump, thereby affecting the production of the entire process and causing economic losses. At the same time, its low safety and low efficiency problems can no longer meet the factory's requirements for safe production.

[0004] In the prior art, the patent publication number is CN112431642A, and the name is an invention of a steam turbine system based on FCB control logic. It discloses that the generator outlet switch is in the closed position, the main transformer high-voltage side outlet switch is in the open position, and the FCB (Fast Cut Back) signal is formed. The digital electro-hydraulic control system (DEH) controls the turbine speed at 3000rpm, and sends the FCB signal to the distributed control system (DCS). After the FCB is actuated, in order to open the regulating door in time and control the turbine at the rated speed, an OPC (OLE for Process Control, OLE applied to process control) function is added. The OPC triggers and then controls the turbine speed to run below 3020rpm, which has the effect of preventing the turbine from overspeeding due to the FCB signal; however, the invention cannot realize the above function on a steam turbine without an OPC solenoid valve, and cannot solve the problem that the three units of this type execute the shutdown interlock value due to the overspeed safety setting, which directly causes the unit to jump. Summary of the invention

[0005] In order to overcome the shortcomings of the above-mentioned prior art, the purpose of the present invention is to propose a three-unit generator disconnection process control system, method, equipment and medium. The system collects the generator disconnection signal and real-time speed data, combines the target speed of the turbine to calculate and output a proportional adjustment parameter to the PID controller for controlling the switch of the turbine main regulating valve, so as to achieve that the three units will not jump due to overspeed after the generator is disconnected from the grid, and the speed of the three units is stabilized at the target speed.

[0006] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0007] In a first aspect, a three-unit generator disconnection process control system includes a signal detection module, an adjustment instruction generation module, and a control execution module:

[0008] The signal detection module comprises a DI (digital input) unit and an AI (analog input) unit, wherein the DI unit is used to detect the generator decoupling signal and transmit it to the adjustment instruction generation module, and the AI ​​unit is used to detect the real-time speed value of the steam turbine and transmit it to the adjustment instruction generation module;

[0009] The regulation instruction generation module includes a PLC controller. When the PLC controller receives a decoupling signal, the PLC controller sends a decoupling instruction to the control execution module. At the same time, the PLC controller starts a decoupling process control program. The decoupling process control program inputs the real-time speed value of the steam turbine received by the PLC controller and the speed setting value of the steam turbine into a linear function, calculates and generates a proportional regulation parameter through the linear function, and the PLC controller dynamically sends the proportional regulation parameter to the control execution module.

[0010] The control execution module includes a PID controller. After receiving the decoupling instruction, the PID controller changes its own control state to automatic mode. The PID controller also includes an AO (analog output) unit. After receiving the proportional adjustment parameter, the PID controller performs internal proportional integral operation and generates a final result. The PID controller converts the final result into a valve position signal through the AO unit and outputs it to the servo system of the turbine main regulating valve.

[0011] Furthermore, the linear function formula is as follows:

[0012] y=k(x1-x0)+b (1)

[0013] In formula (1), y is the proportional adjustment parameter, x0 is the turbine speed setting value, x1 is the turbine real-time speed value, x1-x0 is the speed difference, k is the slope determined by the experiment, and b is the intercept determined by the experiment.

[0014] Furthermore, the adjustment instruction generation module also includes a pulse timer. When the PLC controller starts the decoupling process control program, the PLC controller activates the pulse timer. The pulse timer counts down the execution time of the decoupling process control program. When the execution time is completed, the decoupling process control program automatically terminates and exits.

[0015] In a second aspect, a method for controlling a disconnection process of three generator sets is provided, based on the disconnection process control system, comprising the following steps:

[0016] S1: During the normal operation of the three units, when the DI unit of the signal detection module detects the decoupling signal, the DI unit transmits the decoupling signal to the PLC controller in the adjustment instruction generation module, and at the same time, the AI ​​unit of the signal detection module transmits the detected real-time speed value of the steam turbine to the PLC controller in the adjustment instruction generation module;

[0017] S2: When the PLC controller receives the decoupling signal in step S1, the PLC controller sends a decoupling instruction to the control execution module, and the PLC controller starts a decoupling process control program. The decoupling process control program inputs the real-time speed value of the steam turbine and the speed setting value of the steam turbine received by the PLC controller in step S1 into a linear function, calculates and dynamically generates a proportional adjustment parameter through the linear function, and the PLC controller dynamically sends the proportional adjustment parameter to the control execution module;

[0018] S3: After the PID controller receives the decoupling instruction in step S2, the control state of the PID controller itself is switched to the automatic mode. After receiving the proportional adjustment parameter in step S2, the PID controller performs an internal proportional integral operation and generates a final result. The PID controller converts the final result into a valve position signal through the AO unit and outputs it to the servo system of the main regulating valve of the steam turbine.

[0019] S4: Repeat steps S1 to S3 until the real-time speed value of the steam turbine is stabilized at the steam turbine speed setting value.

[0020] Furthermore, the linear function formula in step S2 is as follows:

[0021] y=k(x1-x0)+b (2)

[0022] In formula (2), y is the proportional adjustment parameter, x0 is the turbine speed setting value, x1 is the turbine real-time speed value, x1-x0 is the speed difference, k is the slope determined by the experiment, and b is the intercept determined by the experiment.

[0023] Furthermore, the adjustment instruction generation module in step S2 also includes a pulse timer. When the PLC controller starts the decoupling process control program, the PLC controller activates the pulse timer. The pulse timer counts down the execution time of the decoupling process control program. When the execution time is completed, the decoupling process control program automatically terminates and exits, and the decoupling process control method terminates at the same time.

[0024] In a third aspect, an electronic device includes a memory and a processor:

[0025] Memory: used for storing a computer program for realizing the decoupling process control system;

[0026] Processor: used to implement the decoupling process control system when executing the computer program.

[0027] According to a fourth aspect, a computer-readable storage medium stores a computer program, wherein the computer program implements the decoupling process control system when executed by a processor.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] 1. This system detects the generator disconnect signal through the DI unit and transmits the signal to the PLC controller. After receiving the disconnect signal, the PLC controller can instantly start the disconnect process control program, which can effectively avoid the three-unit trip caused by overspeed after the generator is disconnected.

[0030] 2. This system uses a linear function to calculate and judge the current operating condition information, assigns real-time output proportional adjustment parameters to the PID controller, and stably controls the turbine speed at the target speed within the pulse time obtained in the test. It has the characteristics of simple calculation and reliable operation.

[0031] In summary, this system can effectively avoid the entire unit tripping due to generator decoupling, ensure the safe and stable operation of production operations, thereby greatly reducing the probability of interlocking reactions of axial flow fans participating in the process due to unit tripping, avoiding unnecessary losses, and significantly improving production reliability and intelligence. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a schematic diagram of the decoupling process control system of the present invention. DETAILED DESCRIPTION

[0033] Combine the following Figure 1 , the present invention is described in further detail.

[0034] In a first aspect, a three-unit generator disconnection process control system includes a signal detection module, an adjustment instruction generation module, and a control execution module:

[0035] The signal detection module includes a DI (Digital Input) unit and an AI (Analog Input) unit. The DI unit is used to detect the generator decoupling signal and transmit the decoupling signal to the adjustment instruction generation module. The decoupling signal specifically refers to the signal that two or more of the three-way grid-connected circuit breakers of the generator are switched from closed to open. The AI ​​unit is used to detect the real-time speed value of the turbine and transmit the real-time speed value of the turbine to the adjustment instruction generation module. The DI unit and AI unit that can be used in this system are conventional equipment, such as Siemens 6ES7321-7BH01-0AB0 and Siemens 6ES7521-1BL00-0AB0, and the AI ​​unit is such as Siemens 6ES7331-7NF00-0AB0 and Siemens 6ES7531-7KF00-0AB0.

[0036] The regulation instruction generation module includes a PLC controller. When the PLC controller receives a disconnection signal, the PLC controller sends a disconnection instruction to the control execution module. At the same time, the PLC controller starts a generator disconnection process control program. The disconnection process control program inputs the real-time speed value of the steam turbine received by the PLC controller and the speed setting value of the steam turbine into a linear function. The linear function calculates and dynamically generates a proportional regulation parameter through the speed difference between the speed setting value and the real-time speed value of the steam turbine. The PLC controller dynamically sends the proportional regulation parameter to the control execution module.

[0037] The control execution module includes a PID controller. After receiving the decoupling instruction, the PID controller forces the control state of the PID controller itself to be converted into automatic mode. Compared with the manual mode, the automatic mode is directly controlled by the PLC controller. The PID controller also includes an AO (Analog Output) unit. After receiving the proportional adjustment parameter, the PID controller performs internal proportional integral operation and generates a final result. The PID controller converts the final result into a valve position signal through the AO unit and outputs it to the servo system of the turbine main regulating valve. The turbine main regulating valve servo system will complete the valve position control through the servo valve according to the received valve position signal to reduce the turbine speed. The AO unit is such as Siemens 6ES7332-5HF00-OAB0 and Siemens 6ES7532-5HF00-0AB0.

[0038] Furthermore, the adjustment instruction generation module also includes a pulse timer. When the PLC controller starts the decoupling process control program, the PLC controller activates the pulse timer. The pulse timer counts down the execution time of the generator decoupling process control program. When the execution time is completed, the decoupling process control program automatically terminates and exits. At this time, the speed control state of the turbine is automatic mode, and the turbine will operate according to the speed setting value in the decoupling process control program. The turbine speed will be maintained at the setting value for a long time. The execution time of the pulse timer, that is, the time required for the turbine speed to stabilize to the speed setting value, is measured by experiment. When the manually set execution time is controlled to be above 10s, the turbine speed will drop from the speed in the decoupling stage and maintain at the speed setting value.

[0039] Second, as Figure 1 As shown, a three-unit generator disconnection process control method, based on the three-unit generator disconnection process control system, comprises the following steps:

[0040] S1: During the normal operation of the three units, when the DI unit of the signal detection module detects the generator disconnection signal, the DI unit transmits the disconnection signal to the adjustment instruction generation module, and at the same time, the AI ​​unit of the signal detection module transmits the detected real-time speed value of the steam turbine to the adjustment instruction generation module;

[0041] S2: When the PLC controller receives the disconnection signal in step S1, the PLC controller sends a disconnection instruction to the control execution module, and the PLC controller starts the generator disconnection process control program. The disconnection process control program inputs the real-time speed value of the steam turbine and the speed setting value of the steam turbine received by the PLC controller in step S1 into a linear function, calculates and dynamically generates a proportional adjustment parameter through the linear function, and the PLC controller dynamically sends the proportional adjustment parameter to the control execution module;

[0042] S3: When the PID controller receives the decoupling instruction described in step S2, the control state of the PID controller itself is forced to be switched to automatic mode. After receiving the proportional adjustment parameter described in step S2, the PID controller performs internal proportional integral operation and generates a final result. The PID controller converts the final result into a valve position signal through the AO unit and outputs it to the servo system of the main regulating valve of the turbine. The servo system of the main regulating valve of the turbine completes the valve position control through the servo valve according to the received valve position signal, gradually adjusts the speed of the turbine to the set value, and finally adjusts the speed of the turbine to the set value within the execution time of the pulse timer.

[0043] S4: Repeat steps S1 to S3 until the real-time speed value of the steam turbine is stabilized at the steam turbine speed setting value.

[0044] Furthermore, the adjustment instruction generation module in step S2 also includes a pulse timer. When the PLC controller starts the decoupling process control program, the PLC controller activates the pulse timer. The pulse timer counts down the execution time of the generator decoupling process control program. When the execution time is completed, the decoupling process control program automatically terminates and exits, and the decoupling process control method terminates at the same time. At this time, the speed control state of the turbine is automatic mode. At this time, the turbine will run according to the speed setting value in the decoupling process control program. The execution time of the pulse timer, that is, the time required for the turbine speed to stabilize to the speed setting value, is measured by experiment. When the manually set execution time is controlled to be above 10s, the turbine speed will be maintained at the speed setting value.

[0045] Example

[0046] The technical solution of the present invention is further described in detail below by taking a three-unit (including a steam turbine, an axial flow fan and a generator) generator decoupling process control system as an embodiment.

[0047] During the normal operation of the three units, the generator power is 10.67MW, and the opening of the main regulating valve of the steam turbine is 28.6%. When the generator is manually disconnected from the power grid, the generator power is immediately reduced to 0MW, the main regulating valve of the steam turbine is reduced to a minimum of 18%, and the maximum speed is 3100rpm. After executing the generator disconnection process control method for 10s, the speed of the steam turbine is stabilized at a set value of about 3000rpm. This experiment proves that the generator disconnection process control system and method of the present invention can effectively control the speed of the steam turbine after the generator is disconnected to above 3100rpm. And within the 10s pulse time adjusted by the generator decoupling process control program, the system can maintain the speed of the three units at 3000rpm, realize the normal operation of the three units, and make the axial flow fan supply air for the process stably. As can be seen from Table 1, the decoupling process control program calculates the proportional adjustment parameters output to the PID controller according to the speed difference between the turbine speed setting value and the real-time speed value (the turbine speed setting value is 3000rpm). The k value and b value in the linear function can be obtained through two groups of test parameters, and the k value and b value can be continuously corrected by using the newly added other test parameters.

[0048] Table 1 Proportional adjustment parameter table generated by the decoupling process control program

[0049] Serial number 1 2 3 4 Speed ​​difference (rpm) 50 100 120 150 Proportional adjustment parameters 0.05 0.08 0.15 0.2

[0050] According to a third aspect, an electronic device includes a memory and a processor, wherein:

[0051] Memory: used to store a computer program for implementing the control system for the three-unit generator decoupling process;

[0052] Processor: used to implement the three-unit generator decoupling process control system when executing the computer program.

[0053] In a fourth aspect, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the three-unit generator decoupling process control system is implemented; the computer-readable storage medium includes: a U disk, a read-only memory (ROM), a random access memory (RAM), a mobile hard disk, a magnetic disk or an optical disk, and other media that can store program codes.

[0054] Working principle of the present invention:

[0055] When the DI unit in the signal detection module detects the generator decoupling signal, it transmits it to the PLC controller in the adjustment instruction generation module. After receiving the decoupling signal, the PLC controller sends a decoupling instruction to the control execution module to change the control state of the PID controller to automatic mode; when the PLC controller receives the decoupling signal, it starts the decoupling process control program, calculates and dynamically outputs the proportional adjustment parameter by receiving the real-time speed value of the turbine transmitted by the AI ​​unit, and outputs the valve position signal to the servo system of the turbine main regulating valve through the AO unit. The servo system completes the valve position control through the servo valve to reduce the turbine speed. By dynamically receiving the real-time speed value of the turbine and dynamically outputting the valve position signal, the turbine speed is finally reduced to the target value within a certain period of time.

Claims

1. A three-unit generator disconnection process control system, characterized in that: Contains signal detection module, adjustment instruction generation module, and control execution module: The signal detection module comprises a DI (digital input) unit and an AI (analog input) unit, wherein the DI unit is used to detect the generator decoupling signal and transmit it to the adjustment instruction generation module, and the AI ​​unit is used to detect the real-time speed value of the steam turbine and transmit it to the adjustment instruction generation module; The regulation instruction generation module includes a PLC controller. When the PLC controller receives a decoupling signal, the PLC controller sends a decoupling instruction to the control execution module. At the same time, the PLC controller starts a decoupling process control program. The decoupling process control program inputs the real-time speed value of the steam turbine received by the PLC controller and the speed setting value of the steam turbine into a linear function, calculates and generates a proportional regulation parameter through the linear function, and the PLC controller dynamically sends the proportional regulation parameter to the control execution module. The control execution module includes a PID controller. After receiving the decoupling instruction, the PID controller changes its own control state to automatic mode. The PID controller also includes an AO (analog output) unit. After receiving the proportional adjustment parameter, the PID controller performs internal proportional integral operation and generates a final result. The PID controller converts the final result into a valve position signal through the AO unit and outputs it to the servo system of the turbine main regulating valve.

2. The decoupling process control system according to claim 1, characterized in that: The linear function formula is as follows: y=k(x1-x0)+b (1) In formula (1), y is the proportional adjustment parameter, x0 is the turbine speed setting value, x1 is the turbine real-time speed value, x1-x0 is the speed difference, k is the slope determined by the experiment, and b is the intercept determined by the experiment.

3. The decoupling process control system according to claim 1, characterized in that: The adjustment instruction generation module also includes a pulse timer. When the PLC controller starts the decoupling process control program, the PLC controller activates the pulse timer. The pulse timer counts down the execution time of the decoupling process control program. When the execution time is completed, the decoupling process control program automatically terminates and exits.

4. A method for controlling the disconnection process of three-unit generators, based on the disconnection process control system according to claim 1, characterized in that: The following steps are involved: S1: During the normal operation of the three units, when the DI unit of the signal detection module detects the decoupling signal, the DI unit transmits the decoupling signal to the PLC controller in the adjustment instruction generation module, and at the same time, the AI ​​unit of the signal detection module transmits the detected real-time speed value of the steam turbine to the PLC controller in the adjustment instruction generation module; S2: When the PLC controller receives the decoupling signal in step S1, the PLC controller sends a decoupling instruction to the control execution module, and the PLC controller starts a decoupling process control program. The decoupling process control program inputs the real-time speed value of the steam turbine and the speed setting value of the steam turbine received by the PLC controller in step S1 into a linear function, calculates and dynamically generates a proportional adjustment parameter through the linear function, and the PLC controller dynamically sends the proportional adjustment parameter to the control execution module; S3: After the PID controller receives the decoupling instruction in step S2, the control state of the PID controller itself is switched to the automatic mode. After receiving the proportional adjustment parameter in step S2, the PID controller performs an internal proportional integral operation and generates a final result. The PID controller converts the final result into a valve position signal through the AO unit and outputs it to the servo system of the main regulating valve of the steam turbine. S4: Repeat steps S1 to S3 until the real-time speed value of the steam turbine is stabilized at the steam turbine speed setting value.

5. The decoupling process control method according to claim 4, characterized in that: The linear function formula in step S2 is as follows: y=k(x1-x0)+b (2) In formula (2), y is the proportional adjustment parameter, x0 is the turbine speed setting value, x1 is the turbine real-time speed value, x1-x0 is the speed difference, k is the slope determined by the experiment, and b is the intercept determined by the experiment.

6. The decoupling process control method according to claim 4, characterized in that: The adjustment instruction generation module in step S2 also includes a pulse timer. When the PLC controller starts the decoupling process control program, the PLC controller activates the pulse timer. The pulse timer counts down the execution time of the decoupling process control program. When the execution time is completed, the decoupling process control program automatically terminates and exits, and the decoupling process control method terminates at the same time.

7. An electronic device, comprising a memory and a processor, characterized in that: Memory: used to store a computer program for implementing the decoupling process control system according to any one of claims 1 to 3; Processor: used to implement the decoupling process control system as claimed in any one of claims 1 to 3 when executing the computer program.

8. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the decoupling process control system according to any one of claims 1 to 3 is implemented.

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