A multi-stage industrial steam supply automatic control method of a combined heat and power system

Abstract

The application discloses a kind of multistage industrial steam supply automatic control methods of heat and power cogeneration system, the method is as follows: one: obtaining the steam flow of each industrial steam supply node of each unit in heat and power cogeneration system;Two: obtain the valve flow characteristic curve of each industrial steam supply node of unit;Three: propose multi-valve coupling flow characteristic and steam valve opening law;Four: add steam valve opening degree bias, with industrial steam supply temperature as feedback signal, realize the slow opening of each industrial steam supply valve, ensure that the opening degree of valve does not appear the working condition of abrupt change;Five: with the deviation signal of actual industrial steam supply pressure and calibration industrial steam supply pressure, output industrial steam supply valve comprehensive adjustment instruction by PID controller;Six: add unit mode switching module in automatic control loop, realize the automatic control under the constitution of different heat and power cogeneration units in system.This method completes related control process while carrying out real-time load distribution in heat and power cogeneration system, auxiliary realization decision-control integration.

Description

Technical Field

[0001] This invention belongs to the field of automatic control of thermal power generation, and relates to an automatic control method for a combined heat and power (CHP) system. Specifically, it relates to an automatic control method for industrial steam supply of a CHP unit after multi-stage industrial steam supply modification, which uses time delay control and temperature offset control. Background Technology

[0002] With the large-scale integration of new energy sources, such as wind power and photovoltaics, into the power grid, higher demands are placed on traditional thermal power units for frequency regulation, peak shaving, valley filling, and heating. Current research on load allocation in combined heat and power (CHP) units largely focuses on traditional CHP units. However, with the improvement of living standards and production levels, heat load and electricity load are no longer simply two different load forms. Some CHP units, especially those serving industrial parks, or integrated CHP systems for industrial parks, not only handle traditional power supply and residential heating loads but also need to supply industrial steam of a certain quality to meet production needs. Therefore, to meet production requirements, these CHP units need to undergo appropriate multi-unit combination and multi-extraction node industrial steam supply modifications based on traditional units, forming multi-unit, multi-level CHP systems. With the increasing proportion of renewable energy grid connection and the growing complexity of CHP production units, the system needs to make load allocation decisions based on real-time operating data to improve overall system efficiency. This leads to frequent load allocation and regulation tasks for CHP systems. Currently, the industrial steam load regulation process in power plants mainly relies on manual adjustments by maintenance personnel. This approach has significant drawbacks: firstly, the limitations of manual adjustment capabilities make it difficult to complete frequent adjustments in response to dispatch instructions; secondly, manual adjustment is a coarse-grained process, prone to significant deviations in accuracy from the allocation decision instructions. Therefore, with the goal of improving the overall operating efficiency of combined heat and power (CHP) systems, and based on obtaining industrial steam load allocation coordinated with power dispatch instructions, establishing an automatic control system for the industrial steam supply system is a key technology for automating power and heat production. Summary of the Invention

[0003] Based on obtaining the electrical load of the cogeneration system and the extraction steam volume of each unit's industrial steam supply nodes through relevant algorithms, this invention proposes a multi-level industrial steam supply automatic control method for the cogeneration system. This method completes the relevant control process while the cogeneration system performs real-time load allocation, thus assisting in the realization of decision-making-control integration.

[0004] The objective of this invention is achieved through the following technical solution:

[0005] A multi-stage industrial steam supply automatic control method for a combined heat and power system includes the following steps:

[0006] Step 1: Calculate the steam supply flow rate of each unit and each industrial steam supply node in the combined heat and power system using a genetic algorithm. ,in The unit number in the system. Number the industrial steam supply nodes for the unit;

[0007] Step 2: Based on historical operating data, use a multinomial regression algorithm to obtain the valve flow characteristic curves of each industrial steam supply node of the unit;

[0008] Step 3: Based on the flow characteristics of each control valve, propose the coupled flow characteristics of multiple control valves and the opening rules of the steam supply control valves;

[0009] Step 4: Based on the steam extraction at each industrial steam extraction node, add an offset to the opening of the steam supply valve. Using the industrial steam supply temperature as the feedback signal, the valves of each industrial steam supply control valve are opened slowly to ensure that there are no sudden changes in the opening of the control valves.

[0010] Step 5: The deviation signal between the actual industrial steam supply pressure and the calibrated industrial steam supply pressure is used to output a comprehensive adjustment command for the industrial steam supply regulating valve through the PID controller.

[0011] Step 6: Add a unit mode switching module to the automatic control loop to realize automatic control under different cogeneration unit configurations in the system.

[0012] Compared with the prior art, the present invention has the following advantages:

[0013] 1) Automatic regulation technology on the turbine side, which is coordinated with grid dispatch instructions, can realize flexible load allocation tasks of the combined heat and power system and improve energy utilization.

[0014] 2) The automatic control of multi-unit, multi-level industrial steam supply systems can overcome the limitations of operation and maintenance personnel in terms of mobility and adjustment accuracy;

[0015] 3) The automatic control system is connected to the power plant's DCS, which allows for more efficient use of multi-source unit operating information compared to traditional operation and maintenance control methods. Attached Figure Description

[0016] Figure 1 Automatic control logic diagram for multi-unit industrial steam supply in a combined heat and power system;

[0017] Figure 2 A family of functions Qa representing the flow characteristics of industrial steam supply regulating valves;

[0018] Figure 3 This is a typical flow characteristic curve of an industrial steam supply regulating valve.

[0019] Figure 4Example diagram of the opening pattern of steam supply regulating valve for multi-machine industrial applications. Detailed Implementation

[0020] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0021] By coordinating load allocation strategies for thermal power units on the power supply side according to grid dispatch instructions, the operational economy of thermal power production units can be further improved. Based on this, to further enhance the automation level of combined heat and power (CHP) systems and achieve automatic control of industrial steam supply valves while alleviating the workload of maintenance personnel, this invention proposes a multi-level industrial steam supply automatic control method for CHP systems. This method first performs multi-unit, multi-level CHP load allocation based on a genetic algorithm; then, it establishes coupled steam supply flow characteristic curves and valve opening rules for each level of industrial steam supply node based on historical operating data of each level of industrial steam supply valve; simultaneously, by introducing pressure and temperature deviation corrections, it ensures a smooth transition during the automatic control process of the CHP system; finally, it constructs a multi-level industrial steam supply automatic control system for the CHP system based on a PID controller and feedback loop. Figure 1 As shown, the specific steps include the following:

[0022] Step 1: Calculate the steam supply flow rate of each unit and each industrial steam supply node in the combined heat and power system using a genetic algorithm. ,in The unit number in the system. Number the industrial steam supply node for the unit.

[0023] This step uses a genetic algorithm (GA) to optimize and solve the overall heat consumption function of the combined heat and power (CHP) system, thereby obtaining the steam supply flow rate of each unit and each industrial steam supply node in the CHP system. The calculation formula for the overall heat consumption function of the CHP system is shown below:

[0024] (1)

[0025] in, For the first The power of each generator set, in kW. For the first in the combined heat and power system The heat consumption of each unit is kJ / (kW·h). It can be calculated using the following formula:

[0026] (2)

[0027] in, For the heat consumption of combined heat and power units, For the first Taiwanese unit Steam extraction capacity at industrial steam supply point No. 1, t / h For the first Taiwanese unit The penalty coefficient for the steam extraction rate at industrial steam supply point No. 1 in heat consumption calculation is dimensionless. This represents the total number of industrial steam supply nodes.

[0028] Step 2: Based on historical operating data, use a multinomial regression algorithm to obtain the valve flow characteristic curves of each industrial steam supply node of the unit.

[0029] This step uses historical operating data of the industrial steam supply regulating valves in a combined heat and power system to identify relevant parameters and derive the flow characteristic curves of the steam supply regulating valves through polynomial regression. The basic mathematical expression of polynomial regression is shown below:

[0030] (3)

[0031] In the formula, For the constant term in the expression, , These are the two variables in the expression.

[0032] Flow rate of industrial steam supply regulating valve in combined heat and power system This can be approximated as the opening degree of an industrial steam supply regulating valve. With regulating valve outlet pressure The function, obtained through the following formula, gives the valve flow characteristics under the second-order polynomial regression algorithm:

[0033] (4)

[0034] To further adapt to the DCS control logic of the combined heat and power system, within the steam supply pressure range The following By iterating through the steam supply pressure, we obtain the family of Qa functions under different pressures. To minimize the pressure on the running data, To handle the maximum pressure in the running data, This represents the pressure gradient during the pressure traversal process, which is the difference between the previous and subsequent pressure values. Figure 2 This is an example of a function family for an industrial steam supply regulating valve. Based on this, a piecewise linear approximation can be used to obtain a piecewise linear function that can be recognized by the DCS system.

[0035] Step 3: Based on the flow characteristics of each control valve, propose the coupling flow characteristics of multiple control valves and the opening rules of the steam supply control valve.

[0036] This step, based on the flow characteristic curves of the industrial steam supply control valves obtained through the above steps, superimposes the control valves to obtain the comprehensive flow characteristic curve of industrial steam extraction, as follows: Figure 3 As shown, the opening pattern of the industrial steam supply regulating valve is obtained by normalizing the flow rate by a percentage, as follows: Figure 4 As shown.

[0037] Step 4: Based on the steam extraction at each industrial steam extraction node, add an offset to the opening of the steam supply valve. Using the industrial steam supply temperature as the feedback signal, the valves of each industrial steam supply control valve are opened slowly to ensure that there are no sudden changes in the valve opening.

[0038] This step is based on the initial design of the maximum offset of the industrial steam supply regulating valve. and in At all times By gradually reducing this bias value, the industrial steam supply regulating valve can be opened slowly. The reduction scale during the gradual decrease of the maximum offset of the industrial steam supply regulating valve opening, i.e., the offset is... - , -2 ...gradually decreasing, the industrial steam supply temperature serves as the feedback signal during the opening process. When the temperature approaches the limit, the offset stops decreasing and instead reaches the next level of industrial steam supply regulating valve. The maximum offset is obtained by the following formula:

[0039] (5)

[0040] in, To optimize the calculated target industrial steam supply control valve opening, For the present The opening degree of the industrial steam supply regulating valve at all times, that is, during the opening process of the industrial steam supply regulating valve. The valve opening at any given time will be identified as .

[0041] Step 5: The deviation signal between the actual industrial steam supply pressure and the calibrated industrial steam supply pressure is used to output a comprehensive adjustment command for the industrial steam supply regulating valve through the PID controller.

[0042] This step achieves pressure control of the industrial steam supply automatic control system by measuring the deviation between the average industrial steam supply pressure of the combined heat and power system and the calibrated industrial steam supply pressure. The average industrial steam supply pressure is obtained by the following formula:

[0043] (6)

[0044] In the formula, For the first Pressure values ​​at the pressure data acquisition point of Unit No. 1 This refers to the total number of industrial steam turbine units in a combined heat and power (CHP) system.

[0045] Step 6: Add a unit mode switching module to the automatic control loop to realize automatic control under different cogeneration unit configurations in the system.

Claims

1. A multi-stage industrial steam supply automatic control method for a combined heat and power system, characterized in that... The method includes the following steps: Step 1: Calculate the steam supply flow rate of each unit and each industrial steam supply node in the combined heat and power system using a genetic algorithm. ,in The unit number in the system. Number the industrial steam supply nodes for the unit; Step 2: Based on historical operating data, use a multinomial regression algorithm to obtain the valve flow characteristic curves of each industrial steam supply node of the unit; Step 3: Based on the flow characteristics of each control valve, propose the coupled flow characteristics of multiple control valves and the opening rules of the steam supply control valves; Step 4: Based on the steam extraction at each industrial steam extraction node, add an offset to the opening of the steam supply valve. Using the industrial steam supply temperature as the feedback signal, the valves of each industrial steam supply control valve are opened slowly to ensure that there are no sudden changes in the opening of the control valves. Step 5: The deviation signal between the actual industrial steam supply pressure and the calibrated industrial steam supply pressure is used to output a comprehensive adjustment command for the industrial steam supply regulating valve through the PID controller. Step 6: Add a unit mode switching module to the automatic control loop to realize automatic control under different cogeneration unit configurations in the system.

2. The multi-stage industrial steam supply automatic control method for a combined heat and power system according to claim 1, characterized in that... In step one, the overall heat consumption function of the combined heat and power system is optimized and solved based on the genetic algorithm to obtain the steam supply flow of each unit and each industrial steam supply node in the combined heat and power system.

3. The multi-stage industrial steam supply automatic control method for a combined heat and power system according to claim 2, characterized in that... The formula for calculating the overall heat consumption function of the combined heat and power system is as follows: in, For the first The power of each generator set For the first in the combined heat and power system The heat consumption of each unit.

4. The multi-stage industrial steam supply automatic control method for a combined heat and power system according to claim 3, characterized in that... The The result is obtained through the following calculation: in, For the heat consumption of combined heat and power units, For the first Taiwanese unit Steam extraction volume at industrial steam supply point No. 1 For the first Taiwanese unit The penalty coefficient for the steam extraction rate at industrial steam supply point No. 1 in heat consumption calculation. This represents the total number of industrial steam supply nodes.

5. The multi-stage industrial steam supply automatic control method for a combined heat and power system according to claim 1, characterized in that... In step two, based on the historical operating data of the industrial steam supply regulating valve of the combined heat and power system, the flow characteristic curve of the steam supply regulating valve is obtained by identifying relevant parameters through polynomial regression. The basic mathematical expression of polynomial regression is shown in the following formula: In the formula, For the constant term in the expression, , These are the two variables in the expression; Flow rate of industrial steam supply regulating valve in combined heat and power system Approximately the opening degree of the industrial steam supply regulating valve With regulating valve outlet pressure The function, obtained through the following formula, gives the valve flow characteristics under the second-order polynomial regression algorithm: To further adapt to the DCS control logic of the combined heat and power system, within the steam supply pressure range The following By iterating through the steam supply pressure, we obtain the family of Qa functions under different pressures. To minimize the pressure on the running data, To handle the maximum pressure in the running data, This represents the pressure gradient during the pressure traversal process.

6. The multi-stage industrial steam supply automatic control method for a combined heat and power system according to claim 1, characterized in that... In step three, based on the flow characteristic curves of the industrial steam supply regulating valves obtained in step two, the comprehensive flow characteristic curve of industrial steam extraction is obtained by superimposing the regulating valves, and the opening pattern of the industrial steam supply regulating valves is obtained by normalizing the flow rate by a percentage.

7. The multi-stage industrial steam supply automatic control method for a combined heat and power system according to claim 1, characterized in that... In step four, the maximum offset of the initially designed industrial steam supply regulating valve is used. and in At all times By gradually reducing this bias value, the industrial steam supply regulating valve can be opened slowly. This is the reduction scale during the process of gradually decreasing the maximum offset of the industrial steam supply regulating valve opening. During the opening process, the industrial steam supply temperature is used as the feedback signal. When the temperature approaches the limit, the offset is no longer reduced, and the adjustment is switched to the next level of industrial steam supply regulating valve.

8. The multi-stage industrial steam supply automatic control method for a combined heat and power system according to claim 7, characterized in that... The maximum bias is obtained by the following formula: in, To optimize the calculated target industrial steam supply control valve opening, For the present The opening degree of the industrial steam supply regulating valve at all times, that is, during the opening process of the industrial steam supply regulating valve. The valve opening at any given time will be identified as .

9. The multi-stage industrial steam supply automatic control method for a combined heat and power system according to claim 1, characterized in that... In step five, the pressure control of the industrial steam supply automatic control system is achieved by the deviation between the average industrial steam supply pressure of the combined heat and power system and the calibrated industrial steam supply pressure.

10. The multi-stage industrial steam supply automatic control method for a combined heat and power system according to claim 9, characterized in that... The average industrial steam supply pressure is obtained by the following formula: In the formula, For the first Pressure values ​​at the pressure data acquisition point of Unit No. 1 This refers to the total number of industrial steam turbine units in a combined heat and power (CHP) system.

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