Method and system for participating in thermal power generating unit coordination control based on high-pressure heater steam extraction throttling

Abstract

According to the thermal power generating unit coordination control method and system based on high pressure heater steam extraction throttling, on the basis of an established coordination controlled mathematical model, the power of a steam turbine is rapidly changed by directly and indirectly controlling the steam extraction flow of a high-pressure cylinder of the steam turbine. The thermal power generating unit is additionally provided with a throttle valve at the 7-section steam extraction position, and the steam inlet flow entering a 7 # high-pressure heater is adjusted under the action of a novel CCS control system. Instruction steam turbine power, an actual main steam pressure signal, a steam turbine power design value and a main steam pressure design value are input, and under the action of the novel CCS control system, output instructions comprise a steam turbine adjusting valve opening instruction, a No.7 high-pressure heater steam inlet adjusting valve opening instruction and a boiler fuel quantity instruction; the load of the steam turbine is adjusted in a steam extraction and throttling mode of the high-pressure heater. When the load instruction is rapidly changed, more time is provided for adjustment of the fuel quantity, the purpose of flexible utilization of stored energy of the steam turbine is achieved, and therefore the rapid load changing capacity of the unit is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal power generation, and in particular relates to a method and system for coordinated control of thermal power units based on high-pressure steam extraction throttling. Background Art

[0002] Electricity is one of the greatest inventions in human history. It has triggered the second wave of industrialization and brought about earth-shaking changes in people's lives.

[0003] The rapid development of renewable energy and the shifting role of the thermal power generation industry are two key challenges facing thermal power generation units: improving their flexibility to facilitate the integration of large-scale renewable energy into the grid; and enhancing their ability to ensure grid power supply security, thereby improving the safety of the grid after the integration of large-scale renewable energy generation.

[0004] The flexibility of thermal power units lies primarily in two aspects: "speed" and "depth." "Speed" refers to faster load-changing rates, higher load regulation accuracy, and improved primary frequency regulation performance. "Depth" refers to a wider load regulation range, with the lower limit reduced from 45% of rated load to 30% or even lower. Solutions to improving the rapid load-changing capabilities of thermal power units primarily address both the boiler and turbine sides. Utilizing the unit's integrated energy storage is an effective technology. Key methods for fully utilizing boiler-side energy storage include rapidly adjusting feedwater flow and attemperating water flow. Key methods for fully utilizing turbine-side energy storage include installing a regulating valve between the turbine's HP and IP cylinders, flexibly utilizing the turbine bypass system, bypassing the HPFW heater, throttling HPFW heater extraction, adjusting deaerator extraction, bypassing the LPFW heater, throttling LPFW heater extraction, and condensate throttling. The above optimization strategies can improve the flexibility of the unit to a certain extent. However, different control strategies have their own limitations. For example, the two methods of deep utilization of boiler-side energy storage are likely to cause drastic changes in the main steam temperature, which is relatively damaging to the boiler. Although the condensate throttling method is effective, it is likely to cause drastic changes in the deaerator water level and requires a complete deaerator water level control system. The change in the low-pressure steam extraction flow rate has little effect on changing the unit load and is difficult to meet the unit's "speed" and "depth" requirements. Deaerator extraction throttling can easily cause insufficient deoxygenation of the boiler feed water. In addition, the deaerator water level will fluctuate, posing a challenge to the relevant control system. Summary of the Invention

[0005] The present invention aims to provide a coordinated control method and system for thermal power units based on high-pressure steam extraction throttling to address issues such as renewable energy grid integration and improving unit load response rates. Based on an established coordinated controlled mathematical model, this method rapidly changes turbine power by directly and indirectly controlling the steam extraction flow rate from the turbine's high-pressure cylinder. When load commands change rapidly, this technology provides more time for fuel adjustment, achieving flexible utilization of the turbine's stored energy and improving the unit's ability to rapidly change loads.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions: A coordinated control system for thermal power units based on high-pressure steam extraction throttling, including high-pressure cylinders, medium-pressure cylinders, low-pressure cylinders, boilers, condensers, No. 1 to 3 low-pressure heaters, deaerators, No. 5 to 7 high-pressure heaters, shaft seal heaters, and a new CCS control system; The superheated steam outlet of the boiler is connected to the high-pressure cylinder, which is equipped with a two-stage extraction steam. The first-stage extraction steam outlet and the second-stage extraction steam outlet of the high-pressure cylinder are respectively connected to the No. 7 high-pressure heater and the No. 6 high-pressure heater, and a throttle valve is provided between the first-stage extraction steam outlet and the No. 7 high-pressure heater. The exhaust steam outlet of the high-pressure cylinder is connected to the boiler, and the hot reheat steam outlet of the boiler is connected to the intermediate-pressure cylinder. The third-stage extraction steam outlet, the fourth-stage extraction steam outlet and the fifth-stage extraction steam outlet of the intermediate-pressure cylinder are respectively connected to the No. 5 high-pressure heater, the deaerator and the No. 3 low-pressure heater; The exhaust outlet of the high-pressure cylinder is connected to the low-pressure cylinder, and the 6th and 7th section extraction outlets of the low-pressure cylinder are connected to the No. 2 low-pressure heater and the No. 1 low-pressure heater respectively; the exhaust outlet of the low-pressure cylinder is connected to the inlet of the condenser, and the outlet of the condenser is connected to the boiler through the shaft seal heater, low-pressure heater, deaerator and high-pressure heater in sequence; The new CCS control system is used to receive turbine power, actual main steam pressure signals, turbine power design value and main steam pressure design value, and can also output turbine regulating valve opening instructions, No. 7 high-pressure heater inlet steam regulating valve opening instructions and boiler fuel quantity instructions.

[0007] A further improvement of the present invention is that the superheated steam outlet of the boiler is connected to the high-pressure cylinder through a main steam valve.

[0008] A further improvement of the present invention is that it further comprises a generator, which is coaxially connected to the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder.

[0009] A further improvement of the present invention is that the new CCS control system includes a traditional CCS coordinated control system and an extraction throttling system. The traditional CCS coordinated control system includes a PID control module, a subtraction module, a summation module, a limit module and a high and low speed limit module. The extraction throttling control system includes a load signal processing module, a PID control module, an algorithm product module, a limit module and a high and low speed limit module; the input command turbine power, the actual main steam pressure signal, the turbine power design value and the main steam pressure design value. Under the action of the new CCS control system, the output command includes a turbine regulating valve opening command, a No. 7 high-pressure steam inlet regulating valve opening command and a boiler fuel quantity command; in the new CCS control system, the designed main steam pressure command p m0 The actual main steam pressure command p m The difference is calculated under the action of the subtraction module to obtain the main steam pressure deviation instruction, which is sent to the PID control module, including PI1, P1, PI2, P2, PI3 and P3, to achieve the adjustment of the control parameters; the pressure deviation instruction passes through the limit module and the high and low speed limit module to achieve the output instruction size deviation and signal instruction speed size control; the turbine regulating valve opening instruction signal and the boiler fuel quantity instruction signal are output to achieve valve opening control and boiler fuel quantity control respectively; Actual turbine power command N T The input is sent to the load signal processing module to remove abnormal data. The output load signal instruction and the turbine power design value are subtracted under the action of the subtraction module to obtain the turbine power deviation instruction. The instruction is sent to the PID control module. The main steam pressure deviation instruction is controlled by PI1 and combined with the power deviation instruction as a feedforward compensation. Under the limit and speed limit links, the turbine regulating valve opening instruction signal is output to achieve its control; the power deviation instruction signal is controlled by PI2 and combined with the pressure deviation instruction signal as a feedforward compensation. Under the limit and speed limit links, the boiler fuel quantity instruction signal is output to control the boiler combustion.

[0010] A method for coordinated control of thermal power generation units based on high-pressure steam extraction throttling, the method is based on the aforementioned method for coordinated control of thermal power generation units based on high-pressure steam extraction throttling, and comprises: The superheated steam at the boiler outlet enters the high-pressure cylinder to expand and do work. The first-stage extraction steam and the second-stage extraction steam of the high-pressure cylinder enter the No. 7 high-pressure heater and the No. 6 high-pressure heater respectively. The exhaust steam from the high-pressure cylinder enters the boiler again, is converted into hot reheat steam, and enters the intermediate-pressure cylinder to expand and perform work. The third-stage extraction steam, fourth-stage extraction steam, and fifth-stage extraction steam from the intermediate-pressure cylinder enter the No. 5 high-pressure heater, deaerator, and No. 3 low-pressure heater respectively; The exhaust steam from the intermediate pressure cylinder enters the low pressure cylinder to expand and do work, while the 6th and 7th stage extraction steam from the low pressure cylinder enter the No. 2 low pressure heater and the No. 1 low pressure heater respectively; The exhaust steam from the low-pressure cylinder enters the condenser to complete condensation. The condensed water passes through the shaft seal heater, low-pressure heater, deaerator, high-pressure heater in turn, and is finally sent to the boiler to complete the entire thermal cycle.

[0011] A further improvement of the present invention is that, under the action of the new CCS control system, the throttle valve adjusts the steam flow entering the No. 7 high-pressure heater, and the turbine load is regulated by throttling the high-pressure heater steam extraction.

[0012] A further improvement of the present invention is that in the new CCS control system, the main steam pressure instruction is designed p m0 The actual main steam pressure command p m By comparison, we can get the main steam pressure deviation instruction and the actual turbine power instruction. N T By comparing with the turbine power design value, the turbine power deviation command is obtained. The main steam pressure deviation command is controlled by PI1 and combined with the power deviation command as feedforward compensation. Under the limit and speed limit links, the turbine regulating valve opening command signal is output to achieve its control; the power deviation command signal is controlled by PI2 and combined with the pressure deviation command signal as feedforward compensation. Under the limit and speed limit links, the boiler fuel quantity command signal is output to control the boiler combustion.

[0013] A further improvement of the present invention is that the input signals of the extraction throttling control system are the turbine power design value and the pressure deviation command signal, respectively. By utilizing the idea of multi-scale signal decomposition, the load command high-frequency signal is extracted, and the high-frequency signal and the main steam pressure deviation signal are respectively subjected to P3 control and PI3 control. Under the action of the limiting and speed limiting links, they jointly output the opening command of the No. 7 high-pressure steam inlet regulating valve.

[0014] A further improvement of the present invention is that, when considering the grid connection of the unit, p m0 is the pressure of the downward pressure curve corresponding to the actual load of the unit, N T0 is the grid load. When the grid load is higher than the actual turbine power instruction N T When the actual main steam pressure instruction p m When the main steam pressure is lower than that corresponding to the sliding pressure curve, combined with the power deviation command signal, the new CCS control system increases the turbine regulating valve opening command, thereby improving the output command of the thermal power unit.

[0015] A further improvement of the present invention is that, in the extraction throttling system, the opening instruction of the No. 7 high-pressure heater steam inlet regulating valve is reduced, the extraction of the high-pressure cylinder is reduced, so that it responds to the increase in the grid load. After the adjustment is completed, the No. 7 high-pressure heater steam inlet regulating valve is opened again; conversely, when the grid load decreases, in order to respond to the reduction in the grid load, the coordinated control system reduces the fuel valve instruction signal and the instruction signal of the main steam valve, reduces the steam inlet flow of the high-pressure cylinder, and increases the opening of the No. 7 high-pressure heater steam inlet regulating valve, so that the work flow in the high-pressure cylinder is reduced. After the response is completed, the opening of the No. 7 high-pressure heater steam inlet regulating valve is restored again, thereby accelerating the response speed of the thermal power unit to the electrical load.

[0016] Compared with the prior art, the present invention has at least the following beneficial technical effects: Compared to traditional thermal power units, the unit described in this invention incorporates a throttle valve at the seventh extraction stage. Under the control of the novel CCS control system, the steam flow rate entering the No. 7 high-pressure heater is regulated, and turbine load regulation is achieved by throttling the extraction steam from the high-pressure heater. The extraction steam flow rate is regulated by installing a throttle valve on the turbine extraction pipe. In traditional thermal power units, the turbine extraction valve is uncontrollable, necessitating the installation of an additional controllable regulating valve and extraction regulating valve mounting structure.

[0017] Furthermore, the new CCS control system utilizes the heat storage characteristics of the feedwater heater. The control model adds an input variable, the extraction steam control valve opening, transforming the traditional "two-input, two-output" coordinated control model structure into a "three-input, two-output" model. In the traditional "two-input, two-output" model, the "two-input" refers to the turbine control valve opening command and the boiler fuel quantity command, while the "two-output" refers to the actual main steam pressure and actual turbine power. The new coordinated control model's "three-input" refers to the turbine control valve opening command, the No. 7 high-pressure heater inlet steam control valve opening command, and the boiler fuel quantity command. When the grid load command changes, the improved boiler-turbine system features a flexible extraction steam system, thereby enhancing the unit's ability to rapidly change loads. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the specific embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0019] Figure 1 Schematic diagram of a coordinated control system for thermal power units based on high-pressure steam extraction throttling according to an embodiment of the present invention; Figure 2Schematic diagram of a novel CCS control system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0020] Hereinafter, only certain exemplary embodiments are briefly described. As will be appreciated by those skilled in the art, the described embodiments may be modified in various ways without departing from the spirit or scope of the present invention. Therefore, the drawings and description are to be considered as illustrative in nature and not restrictive.

[0021] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential" and the like to indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0022] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of the technical features being referred to. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of such features. In the description of the present invention, "plurality" means two or more, unless otherwise specifically defined.

[0023] In the present invention, unless otherwise expressly specified or limited, terms such as "mounted," "connected," "connect," and "fixed" should be understood broadly. For example, they may refer to fixed connection, detachable connection, or integration; mechanical connection, electrical connection, or communication; direct connection or indirect connection through an intermediate medium; and internal communication between two components or interaction between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0024] In the present invention, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may include the first and second features being in direct contact, or may include the first and second features being in contact not directly but through another feature between them. Furthermore, a first feature being "above," "above," and "above" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may include the first feature being directly above or obliquely above the second feature, or may simply mean that the first feature is lower in level than the second feature.

[0025] It will be understood that when used in this specification and the appended claims, the terms “comprises” and “comprising” indicate the presence of described features, integers, steps, operations, elements and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0026] It should also be understood that the terms used in the present specification are only for the purpose of describing particular embodiments and are not intended to limit the present invention. As used in the present specification and the appended claims, the singular forms "a", "an", and "the" are intended to include the plural forms unless the context clearly indicates otherwise.

[0027] It should be further understood that the term "and / or" used in the present description and the appended claims refers to and includes any and all possible combinations of one or more of the associated listed items.

[0028] The accompanying drawings illustrate various schematic diagrams of structures according to embodiments disclosed herein. These figures are not drawn to scale; for clarity, some details are exaggerated and some details may be omitted. The shapes of the various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary and may deviate in practice due to manufacturing tolerances or technical limitations. Those skilled in the art may design regions / layers with different shapes, sizes, and relative positions as needed.

[0029] The embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0030] Example 1 The present invention provides a coordinated control system for a thermal power unit based on high-pressure steam extraction and throttling, comprising a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a boiler, a condenser, a generator, low-pressure heaters No. 1 to No. 3, a deaerator, high-pressure heaters No. 5 to No. 7, a shaft seal heater, and a novel CCS control system. In the thermal power unit, superheated steam from the boiler outlet, under the action of the main steam valve, enters the high-pressure cylinder (HP) to expand and perform work. The HPC has two stages of steam extraction: the first and second stages of steam extraction from the HPC enter high-pressure heater No. 7 (GJ7) and high-pressure heater No. 6 (GJ6), respectively. A throttle valve (V1) is added between the first stage of steam extraction and the HPC heater No. 7. The exhaust steam from the high-pressure cylinder enters the boiler again, is converted into hot reheat steam, and enters the intermediate-pressure cylinder to expand and perform work. There are three-stage extraction steam, four-stage extraction steam, and five-stage extraction steam in the intermediate-pressure cylinder, which respectively enter the No. 5 high-pressure heater GJ5, the deaerator, and the No. 3 low-pressure heater DJ3; The exhaust steam from the intermediate pressure cylinder enters the low pressure cylinder to expand and do work, while the 6th and 7th stage extraction steam from the low pressure cylinder enter the No. 2 low pressure heater DJ2 and the No. 1 low pressure heater DJ1 respectively; The exhaust steam from the low-pressure cylinder enters the condenser to complete condensation. The condensed water passes through the shaft seal heater, low-pressure heater, deaerator, high-pressure heater in turn, and is finally sent to the boiler to complete the entire thermal cycle.

[0031] In this embodiment, compared to conventional thermal power plants, the present invention incorporates a throttle valve at the seventh extraction stage. Under the control of the novel CCS control system, the steam flow rate entering the No. 7 high-pressure heater GJ7 is regulated, and turbine load regulation is achieved by throttling the extraction steam from the high-pressure heater. The extraction steam flow rate is regulated by installing a throttle valve on the turbine extraction pipe. In conventional thermal power plants, the turbine extraction valve is uncontrollable, necessitating the installation of an additional controllable regulating valve and extraction regulating valve mounting structure.

[0032] In this embodiment, the novel CCS control system utilizes the heat storage characteristics of the feedwater heater. The control model adds an input variable, the extraction control valve opening, to transform the traditional "two-input, two-output" coordinated control model structure into a "three-input, two-output" form. In the traditional "two-input, two-output" model, the "two-input" refers to the turbine control valve opening instruction and the boiler fuel quantity instruction, and the "two-output" refers to the actual main steam pressure and the actual turbine power. The novel coordinated control model's "three-input" refers to the turbine control valve opening instruction, the No. 7 high-pressure heater inlet steam control valve opening instruction, and the boiler fuel quantity instruction. When the grid load instruction changes, the improved boiler-turbine system has a flexible extraction system, thereby improving the unit's ability to quickly change loads.

[0033] In this embodiment, for the design of the new CCS control system of the unit, the input is the command turbine power, the actual main steam pressure signal, the turbine power design value and the main steam pressure design value. Under the action of the new CCS control system, the output instructions include the turbine regulating valve opening instruction, the No. 7 high-pressure steam inlet regulating valve opening instruction and the boiler fuel quantity instruction. In the new CCS control system, the designed main steam pressure instruction p m0 The actual main steam pressure command p m By comparison, we can get the main steam pressure deviation instruction and the actual turbine power instruction. N T By comparing with the turbine power design value, the turbine power deviation command is obtained. The main steam pressure deviation command is controlled by PI1 and combined with the power deviation command as feedforward compensation. Under the limit and speed limit links, the turbine regulating valve opening command signal is output to achieve its control; the power deviation command signal is controlled by PI2 and combined with the pressure deviation command signal as feedforward compensation. Under the limit and speed limit links, the boiler fuel quantity command signal is output to control the boiler combustion.

[0034] In this embodiment, the input signals of the extraction throttling control system are the turbine power design value and the pressure deviation command signal. The multi-scale decomposition concept of the signal is used to extract the high-frequency signal of the load command. The high-frequency signal and the main steam pressure deviation signal are respectively subjected to P3 control and PI3 control. Under the action of the limiting and speed limiting links, the opening command of the No. 7 high-pressure feedwater heater inlet steam regulating valve is jointly output. This is because the No. 7 high-pressure feedwater heater has a greater impact on the unit, so the opening command of the No. 7 high-pressure feedwater heater inlet steam regulating valve of the turbine is used as the control variable.

[0035] In this embodiment, when considering the grid connection of the unit, p m0 It can be considered as the pressure of the downward pressure curve corresponding to the actual load of the unit. N T0 Considering the grid load, when the grid load is higher than the actual turbine power instruction N T When the actual main steam pressure instruction p mWhen the main steam pressure falls below the corresponding sliding pressure curve, the new CCS control system, combined with the power deviation command signal, increases the turbine control valve opening command, thereby increasing the output command of the thermal power unit. Furthermore, in the extraction throttling system, the opening command of the No. 7 high-pressure heater inlet steam control valve is reduced, reducing steam extraction to the high-pressure cylinder, enabling it to quickly respond to increased grid load. Once the adjustment is completed, the No. 7 high-pressure heater inlet steam control valve is reopened. Conversely, when the grid load decreases, the coordinated control system reduces the fuel valve command signal and the main steam valve command signal to respond to the decrease in grid load. This reduces the steam inlet flow to the high-pressure cylinder and increases the opening of the No. 7 high-pressure heater inlet steam control valve, reducing the work flow in the high-pressure cylinder. Once the response is completed, the opening of the No. 7 high-pressure heater inlet steam control valve is restored, accelerating the thermal power unit's response to electrical load.

[0036] Example 2 See also Figure 1 The present invention provides a coordinated control system for thermal power generation units based on high-pressure extraction throttling, which includes a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a boiler, a condenser, a generator, low-pressure heaters No. 1 to No. 3, a deaerator, high-pressure heaters No. 5 to No. 7, a shaft seal heater and a new CCS control system. In the thermal power generation unit, the superheated steam at the boiler outlet enters the high-pressure cylinder HP under the action of the main steam valve to expand and perform work. There are two stages of extraction in the high-pressure cylinder. The first stage extraction and the second stage extraction of the high-pressure cylinder enter the No. 7 high-pressure heater GJ7 and the No. 6 high-pressure heater GJ6 respectively. A throttle valve V1 is added from the first stage extraction to the No. 7 high-pressure heater; further, the exhaust steam of the high-pressure cylinder enters the boiler again, is converted into hot reheat steam, and enters the intermediate-pressure cylinder to expand and perform work. There are three-stage extraction, four-stage extraction and The five-stage extraction steam enters the No. 5 high-pressure heater GJ5, the deaerator, and the No. 3 low-pressure heater DJ3 respectively; further, the exhaust steam from the intermediate-pressure cylinder enters the low-pressure cylinder to expand and perform work, and the 6th and 7th stage extraction steam from the low-pressure cylinder enter the No. 2 low-pressure heater DJ2 and the No. 1 low-pressure heater DJ1 respectively; further, the exhaust steam from the low-pressure cylinder enters the condenser to complete condensation. The condensed condensate passes through the shaft seal heater, low-pressure heater, deaerator, and high-pressure heater in sequence, and is finally sent to the boiler to complete the entire thermodynamic cycle. Compared with traditional thermal power units, the thermal power unit described in the present invention has a throttle valve added at the 7th stage extraction steam. Under the action of the new CCS control system, the steam inlet flow entering the No. 7 high-pressure heater GJ7 is adjusted, and the turbine load is regulated by throttling the high-pressure heater extraction steam. The extraction steam flow is regulated by installing a throttle valve on the turbine extraction steam pipeline. In traditional thermal power units, the steam turbine extraction valve is a non-controllable valve, so it is necessary to additionally install a controllable regulating valve and a steam extraction regulating valve installation structure.

[0037] See also Figure 2Schematic diagram of the novel CCS control system according to an embodiment of the present invention. This new coordinated control technology utilizes the heat storage characteristics of the feedwater heater. This control model adds an input variable, the extraction steam control valve opening, transforming the traditional "two-input, two-output" coordinated control model structure into a "three-input, two-output" model. When grid load demands change, the improved boiler-turbine system features a flexible extraction steam system, enhancing the unit's ability to rapidly change loads.

[0038] Example 3 The present invention provides a method for coordinated control of thermal power units based on high-pressure steam extraction throttling, comprising: The superheated steam at the boiler outlet enters the high-pressure cylinder to expand and perform work, and the first-stage extraction steam and the second-stage extraction steam of the high-pressure cylinder enter the No. 7 high-pressure heater and the No. 6 high-pressure heater respectively; the exhaust steam of the high-pressure cylinder enters the boiler again, converted into hot reheat steam, and enters the intermediate-pressure cylinder to expand and perform work, and the third-stage extraction steam, the fourth-stage extraction steam and the fifth-stage extraction steam of the intermediate-pressure cylinder enter the No. 5 high-pressure heater, the deaerator and the No. 3 low-pressure heater respectively; the exhaust steam of the intermediate-pressure cylinder enters the low-pressure cylinder to expand and perform work, and the sixth-stage extraction steam and the seventh-stage extraction steam of the low-pressure cylinder enter the No. 2 low-pressure heater and the No. 1 low-pressure heater respectively; the exhaust steam of the low-pressure cylinder enters the condenser to complete condensation, and the condensed condensate passes through the shaft seal heater, the low-pressure heater, the deaerator and the high-pressure heater in turn, and is finally sent to the boiler to complete the entire thermal cycle.

[0039] For the design of the unit's new CCS control system, the input instructions are turbine power, actual main steam pressure signal, turbine power design value and main steam pressure design value. Under the action of the new CCS control system, the output instructions include turbine regulating valve opening instruction, No. 7 high-pressure heater inlet steam regulating valve opening instruction and boiler fuel quantity instruction.

[0040] First, the designed main steam pressure instruction p m0 The actual main steam pressure command p m By comparison, we can get the main steam pressure deviation instruction and the actual turbine power instruction. N T By comparing with the turbine power design value, the turbine power deviation command is obtained. The main steam pressure deviation command is controlled by PI1 and combined with the power deviation command as feedforward compensation. Under the limit and speed limit links, the turbine regulating valve opening command signal is output to achieve its control.

[0041] Secondly, the power deviation command signal is controlled by PI2 and combined with the pressure deviation command signal as feedforward compensation. Under the limit and speed limit links, the boiler fuel quantity command signal is output to control the combustion of the boiler.

[0042] Finally, the input signals of the extraction throttling control system are the turbine power design value and the pressure deviation command signal. The idea of multi-scale signal decomposition is used to extract the high-frequency signal of the load command. The high-frequency signal and the main steam pressure deviation signal are respectively controlled by P3 and PI3. Under the action of the limiting and speed limiting links, the opening command of the No. 7 high-pressure feedwater heater inlet steam regulating valve is jointly output. This is because the No. 7 high-pressure feedwater heater has a greater impact on the unit, so the opening command of the No. 7 high-pressure feedwater heater inlet steam regulating valve of the turbine is used as the control variable.

[0043] When considering unit grid connection, p m0 It can be considered as the pressure of the downward pressure curve corresponding to the actual load of the unit. N T0 Considering the grid load, when the grid load is higher than the actual turbine power instruction N T When the actual main steam pressure instruction p m When the main steam pressure falls below the corresponding sliding pressure curve, the new CCS control system, combined with the power deviation command signal, increases the turbine control valve opening command, thereby increasing the output command of the thermal power unit. Furthermore, in the extraction throttling system, the opening command of the No. 7 high-pressure heater inlet steam control valve is reduced, reducing steam extraction to the high-pressure cylinder, enabling it to quickly respond to increased grid load. Once the adjustment is completed, the No. 7 high-pressure heater inlet steam control valve is reopened. Conversely, when the grid load decreases, the coordinated control system reduces the fuel valve command signal and the main steam valve command signal to respond to the decrease in grid load. This reduces the steam inlet flow to the high-pressure cylinder and increases the opening of the No. 7 high-pressure heater inlet steam control valve, reducing the work flow in the high-pressure cylinder. Once the response is completed, the opening of the No. 7 high-pressure heater inlet steam control valve is restored, accelerating the thermal power unit's response to electrical load.

[0044] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It is obvious to those skilled in the art that the present invention is not limited to the details of the above exemplary embodiments, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, from all points of view, the embodiments should be regarded as illustrative and non-restrictive. The scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes that fall within the meaning and range of equivalents of the claims are included in the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0045] In addition, it should be understood that although this specification describes the embodiments, not every embodiment contains only one independent technical solution. This description is for clarity only. Those skilled in the art should consider the specification as a whole. The technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for the purpose of illustrating the technical concept of the present invention and cannot be used to limit the scope of protection of the present invention. Any changes made based on the technical solution in accordance with the technical concept proposed by the present invention fall within the scope of protection of the claims of the present invention.

Claims

1. A coordinated control system for thermal power units based on high-pressure steam extraction throttling, characterized in that: It includes high-pressure cylinder, medium-pressure cylinder, low-pressure cylinder, boiler, condenser, No. 1 to 3 low-pressure heaters, deaerator, No. 5 to 7 high-pressure heaters, shaft seal heater and new CCS control system; The superheated steam outlet of the boiler is connected to the high-pressure cylinder, which is equipped with a two-stage extraction steam. The first-stage extraction steam outlet and the second-stage extraction steam outlet of the high-pressure cylinder are respectively connected to the No. 7 high-pressure heater and the No. 6 high-pressure heater, and a throttle valve is provided between the first-stage extraction steam outlet and the No. 7 high-pressure heater. The exhaust steam outlet of the high-pressure cylinder is connected to the boiler, and the hot reheat steam outlet of the boiler is connected to the intermediate-pressure cylinder. The third-stage extraction steam outlet, the fourth-stage extraction steam outlet and the fifth-stage extraction steam outlet of the intermediate-pressure cylinder are respectively connected to the No. 5 high-pressure heater, the deaerator and the No. 3 low-pressure heater; The exhaust outlet of the high-pressure cylinder is connected to the low-pressure cylinder, and the 6th and 7th section extraction outlets of the low-pressure cylinder are connected to the No. 2 low-pressure heater and the No. 1 low-pressure heater respectively; the exhaust outlet of the low-pressure cylinder is connected to the inlet of the condenser, and the outlet of the condenser is connected to the boiler through the shaft seal heater, low-pressure heater, deaerator and high-pressure heater in sequence; The new CCS control system is used to receive turbine power, actual main steam pressure signals, turbine power design value and main steam pressure design value, and can also output turbine regulating valve opening instructions, No. 7 high-pressure heater inlet steam regulating valve opening instructions and boiler fuel quantity instructions.

2. A coordinated control system for thermal power generation units based on high-pressure steam extraction throttling according to claim 1, characterized in that: The superheated steam outlet of the boiler is connected to the high-pressure cylinder through the main steam valve.

3. The coordinated control system for thermal power generation units based on high-pressure steam extraction throttling according to claim 1 is characterized in that: It also includes a generator, which is coaxially connected to the high-pressure cylinder, the medium-pressure cylinder and the low-pressure cylinder.

4. A coordinated control system for thermal power generation units based on high-pressure steam extraction throttling according to claim 1, characterized in that: The new CCS control system includes the traditional CCS coordinated control system and the extraction throttling system. The traditional CCS coordinated control system includes a PID control module, a subtraction module, a summation module, a limit module and a high and low speed limit module. The extraction throttling control system includes a load signal processing module, a PID control module, an algorithm product module, a limit module and a high and low speed limit module; the input command turbine power, the actual main steam pressure signal, the turbine power design value and the main steam pressure design value. Under the action of the new CCS control system, the output command includes the turbine regulating valve opening command, the No. 7 high-pressure steam inlet regulating valve opening command and the boiler fuel quantity command; in the new CCS control system, the designed main steam pressure command p m0 The actual main steam pressure command p m The difference is calculated under the action of the subtraction module to obtain the main steam pressure deviation instruction, which is sent to the PID control module, including PI1, P1, PI2, P2, PI3 and P3, to achieve the adjustment of the control parameters; the pressure deviation instruction passes through the limit module and the high and low speed limit module to achieve the output instruction size deviation and signal instruction speed size control; the turbine regulating valve opening instruction signal and the boiler fuel quantity instruction signal are output to achieve valve opening control and boiler fuel quantity control respectively; Actual turbine power command N T The input is sent to the load signal processing module to remove abnormal data. The output load signal instruction and the turbine power design value are subtracted under the action of the subtraction module to obtain the turbine power deviation instruction. The instruction is sent to the PID control module. The main steam pressure deviation instruction is controlled by PI1 and combined with the power deviation instruction as a feedforward compensation. Under the limit and speed limit links, the turbine regulating valve opening instruction signal is output to achieve its control; the power deviation instruction signal is controlled by PI2 and combined with the pressure deviation instruction signal as a feedforward compensation. Under the limit and speed limit links, the boiler fuel quantity instruction signal is output to control the boiler combustion.

5. A method for coordinated control of thermal power units based on high-pressure steam extraction throttling, characterized in that: The method is based on a coordinated control system for thermal power units based on high-pressure steam extraction throttling as described in claim 4, and comprises: The superheated steam at the boiler outlet enters the high-pressure cylinder to expand and do work. The first-stage extraction steam and the second-stage extraction steam of the high-pressure cylinder enter the No. 7 high-pressure heater and the No. 6 high-pressure heater respectively. The exhaust steam from the high-pressure cylinder enters the boiler again, is converted into hot reheat steam, and enters the intermediate-pressure cylinder to expand and perform work. The third-stage extraction steam, fourth-stage extraction steam, and fifth-stage extraction steam from the intermediate-pressure cylinder enter the No. 5 high-pressure heater, deaerator, and No. 3 low-pressure heater respectively; The exhaust steam from the intermediate pressure cylinder enters the low pressure cylinder to expand and do work, while the 6th and 7th stage extraction steam from the low pressure cylinder enter the No. 2 low pressure heater and the No. 1 low pressure heater respectively; The exhaust steam from the low-pressure cylinder enters the condenser to complete condensation. The condensed water passes through the shaft seal heater, low-pressure heater, deaerator, high-pressure heater in turn, and is finally sent to the boiler to complete the entire thermal cycle.

6. The method for coordinated control of thermal power generation units based on high-pressure steam extraction throttling according to claim 5 is characterized in that: Under the action of the new CCS control system, the throttle valve adjusts the steam flow entering the No. 7 high-pressure heater, and the turbine load is regulated by throttling the high-pressure heater steam extraction.

7. The method for coordinated control of thermal power units based on high-pressure steam extraction throttling according to claim 5 is characterized in that: In the new CCS control system, the main steam pressure command is designed p m0 The actual main steam pressure command p m By comparison, we can get the main steam pressure deviation instruction and the actual turbine power instruction. N T By comparing with the turbine power design value, the turbine power deviation command is obtained. The main steam pressure deviation command is controlled by PI1 and combined with the power deviation command as feedforward compensation. Under the limit and speed limit links, the turbine regulating valve opening command signal is output to achieve its control; the power deviation command signal is controlled by PI2 and combined with the pressure deviation command signal as feedforward compensation. Under the limit and speed limit links, the boiler fuel quantity command signal is output to control the boiler combustion.

8. The method for coordinated control of thermal power units based on high-pressure steam extraction throttling according to claim 6 is characterized in that: The input signals of the extraction throttling control system are the turbine power design value and the pressure deviation command signal. The idea of multi-scale signal decomposition is used to extract the high-frequency signal of the load command. The high-frequency signal and the main steam pressure deviation signal are respectively controlled by P3 and PI3. Under the action of the limiting and speed limiting links, they jointly output the opening command of the No. 7 high-pressure heater inlet steam regulating valve.

9. The method for coordinated control of thermal power generation units based on high-pressure steam extraction throttling according to claim 6 is characterized in that: When considering the grid connection of the unit, let p m0 is the pressure of the downward pressure curve corresponding to the actual load of the unit, N T0 is the grid load. When the grid load is higher than the actual turbine power instruction N T When the actual main steam pressure instruction p m When the main steam pressure is lower than that corresponding to the sliding pressure curve, combined with the power deviation command signal, the new CCS control system increases the turbine regulating valve opening command, thereby improving the output command of the thermal power unit.

10. The method for coordinated control of thermal power generation units based on high-pressure steam extraction throttling according to claim 9, characterized in that: In the extraction throttling system, the opening command of the No. 7 high-pressure heater steam inlet regulating valve is reduced, and the extraction of the high-pressure cylinder is reduced to respond to the increase in the grid load. After the adjustment is completed, the No. 7 high-pressure heater steam inlet regulating valve is opened again; conversely, when the grid load decreases, in order to respond to the decrease in the grid load, the coordinated control system reduces the fuel valve command signal and the command signal of the main steam valve, reduces the steam inlet flow of the high-pressure cylinder, and increases the opening of the No. 7 high-pressure heater steam inlet regulating valve, so that the work flow in the high-pressure cylinder is reduced. After the response is completed, the opening of the No. 7 high-pressure heater steam inlet regulating valve is restored again to speed up the response speed of the thermal power unit to the electrical load.

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