Control system and method for participating in variable load response of thermal power generating unit based on water supply bypass

Abstract

The invention relates to the technical field of thermal power generating unit coordination control, in particular to a control system and method for participating in thermal power generating unit variable load response based on a water supply bypass. The control system participating in the variable load response of the thermal power generating unit based on the water supply bypass comprises a thermal power generating unit system, and the thermal power generating unit system comprises a heating system, a multi-section pressure steam exhaust system and a condensation circulation system; the heating system is used for heating and generating steam; the multi-section pressure steam exhaust system comprises a high-pressure steam exhaust system, a medium-pressure steam exhaust system, a low-pressure steam exhaust system and a high-pressure steam exhaust system; the condensation circulation system is used for condensing the low-pressure exhaust steam and circulating the low-pressure exhaust steam to the heating system to form thermodynamic circulation; the instruction system inputs a design steam turbine power instruction, a design main steam pressure instruction, an actual steam turbine power instruction and an actual main steam pressure instruction; the novel CCS control system outputs and controls the opening degree of a turbine adjusting valve, high-pressure heater water supply bypass adjustment and boiler fuel quantity instructions to adjust the steam extraction amount and the steam inlet flow of the high-pressure steam exhaust system.

Description

Technical Field

[0001] This invention relates to the field of coordinated control technology for thermal power units, specifically to a control system and method based on feedwater bypass participating in the load change response of thermal power units. Background Technology

[0002] Faced with the common challenges of dwindling fossil fuels, environmental pollution, and climate change, vigorously developing and utilizing new energy sources such as wind, solar, and biomass energy, while improving the efficiency of traditional energy utilization, has become a basic consensus and response strategy for countries worldwide. In my country's energy structure, thermal power accounts for 68.97% of total installed capacity; hydropower accounts for 22.45%; nuclear power accounts for 1.17%; and gas-fired and oil-fired power generation accounts for less than 3%. The proportion of gas-fired and oil-fired power generation, capable of rapidly responding to fluctuating power sources such as wind power, is extremely low. Furthermore, most of my country's hydropower stations are run-of-river hydropower stations, exhibiting significant seasonal characteristics. The water storage in reservoirs, besides power generation, also needs to meet flood control and agricultural irrigation needs, thus limiting the peak-shaving capacity of hydropower. Therefore, improving the rapid load-change operation capability of thermal power units will be an inevitable choice for my country's large-scale adoption of new energy power.

[0003] In recent years, my country has witnessed the rapid development of renewable energy sources such as wind and solar power, effectively reducing environmental pollution from traditional fossil fuels and improving energy efficiency. However, the instability of renewable energy generation means that coal-fired power generation, primarily based on coal-fired units, will remain the dominant force in the energy structure, a situation unlikely to change for a considerable period. Therefore, enhancing the flexibility of coal-fired power units is crucial to increasing renewable energy generation.

[0004] To better ensure the safe and stable operation of the power grid and mitigate the impact of new energy power on the grid, it is necessary to continuously enhance the rapid response capability of power sources. However, thermal power generation still dominates my country's energy structure; therefore, improving the rapid load-change capability of thermal power units is an inevitable choice for my country's large-scale adoption of new energy power. Although traditional thermal power units have a certain load-change capability, their load-change rate still cannot meet the needs of the power grid.

[0005] In current thermal power units, the method of directly installing regulating valves in the turbine extraction section to throttle the extraction steam from the high-pressure heater can quickly change the turbine load and effectively improve the unit's flexibility. However, some thermal power units have limitations on the rate of change of extraction steam temperature in their feedwater heaters. If such units frequently use high-pressure heater throttling technology to change load, it will inevitably cause damage to the heaters and affect the economic benefits of thermal power plants. Summary of the Invention

[0006] The purpose of this invention is to provide a control system based on feedwater bypass participating in the load change response of thermal power units, so as to solve the problem of heater damage caused by frequent load changes in thermal power units through high-pressure heater throttling technology in the prior art.

[0007] To solve the above problems, the technical solution of the control system based on feedwater bypass participating in the load change response of thermal power units in this invention is as follows: A control system based on feedwater bypass participating in the load change response of thermal power units includes: The thermal power unit system, command system, and new CCS control system, wherein the thermal power unit system includes a heating system, a multi-stage pressure exhaust system, and a condensing cycle system; The heating system is used to heat and generate steam; The multi-stage pressure exhaust system includes a high-pressure exhaust system, a medium-pressure exhaust system, and a low-pressure exhaust system connected in sequence. The high-pressure exhaust system is used to extract steam generated by the heating system under the regulation and control of the new CCS control system to obtain high-pressure exhaust steam. After being reheated by the heating system, the high-pressure exhaust steam enters the high-pressure exhaust system, the medium-pressure exhaust system, and the low-pressure exhaust system in sequence for extraction to obtain low-pressure exhaust steam. The condensation cycle system is used to condense the low-pressure exhaust steam and circulate it to the heating system to form a thermodynamic cycle. The command system is used to input design turbine power commands and design main steam pressure commands to the new CCS control system, and to input actual turbine power commands and actual main steam pressure commands to the thermal power unit system. The novel CCS control system is used to output and control the turbine regulating valve opening command, the high-pressure feedwater bypass regulation command, and the boiler fuel quantity command to regulate the extraction steam volume of the high-pressure exhaust system and control the steam inlet flow into the high-pressure exhaust system.

[0008] Optionally, the novel CCS control system includes a traditional CCS control system and a high-pressure water supply bypass throttling control system. The conventional CCS control system includes a turbine regulating valve opening command module and a boiler fuel quantity command module. The turbine regulating valve opening command module is used to output turbine regulating valve opening commands to control the steam flow rate entering the high-pressure exhaust system; the boiler fuel quantity command module is used to output boiler fuel quantity commands to control the amount of steam generated by the heating system. The high-pressure heater feedwater bypass throttling control system is connected to the high-pressure exhaust system. It includes a high-pressure heater feedwater bypass adjustment command module, which is used to output high-pressure heater feedwater bypass adjustment commands to adjust the amount of steam extracted by the feedwater in the high-pressure exhaust system.

[0009] Optionally, the command system includes a main steam pressure deviation command and a turbine power deviation command, wherein the main steam pressure deviation command is the difference between the designed main steam pressure command and the actual main steam pressure command; and the turbine power deviation command is the difference between the designed turbine power command and the actual turbine power command.

[0010] Optionally, the high-pressure feedwater bypass throttling control system further includes a load signal processing module, which is used to process the design turbine power command to obtain low-frequency and high-frequency signals of the load command; The control method of the turbine regulating valve opening command module is as follows: The low-frequency signal of the load command and the turbine power deviation command are used as feedforward compensation and are superimposed on the main steam pressure deviation command. Under the action of amplitude and speed limiting, the turbine regulating valve opening command is output to control the steam flow into the high-pressure exhaust system, thereby controlling the output power of the thermal power unit.

[0011] Optionally, the control method of the boiler fuel quantity command module is as follows: The turbine power deviation command, combined with the main steam pressure deviation command, serves as feedforward compensation. Under the effects of amplitude and speed limiting, the output furnace fuel quantity command controls the amount of steam generated by the heating system, thereby controlling the steam flow rate entering the high-pressure exhaust system.

[0012] Optionally, the control method of the high-pressure water supply bypass regulating module is as follows: By combining the turbine power command and the main steam pressure deviation command, the high-frequency signal of the load command is extracted. Under the action of amplitude limiting and speed limiting, the high-frequency signal and the main steam pressure deviation command output the high-pressure heater feedwater bypass regulation command to regulate the steam extraction rate of feedwater in the high-pressure exhaust system. Optionally, the high-pressure exhaust system includes a high-pressure cylinder, a first-stage extraction module, and a second-stage extraction module. The high-pressure heater feedwater bypass throttling control system is connected to the first-stage extraction module, and a high-pressure heater feedwater bypass regulating valve is provided between the first-stage extraction module and the second-stage extraction module.

[0013] Optionally, in the multi-stage pressure exhaust system, the high-pressure exhaust system is used to extract steam generated by the heating system under the regulation and control of the new CCS control system to obtain high-pressure exhaust, and to transfer the reheated steam generated by the high-pressure exhaust of the heating system to the medium-pressure exhaust system; the medium-pressure exhaust system is used to extract reheated steam at medium pressure to obtain medium-pressure exhaust; and the low-pressure exhaust system is used to extract medium-pressure exhaust from the medium-pressure exhaust to obtain low-pressure exhaust.

[0014] This application also provides a control method based on feedwater bypass participation in the variable load response of thermal power units. The control system based on the above-described feedwater bypass participation in the variable load response of thermal power units includes the following steps: S1. Steam is generated by a heating system; S2. Input the design turbine power command and design main steam pressure command to the new CCS control system through the command system, and input the actual turbine power command and actual main steam pressure command to the thermal power unit system; output and control the turbine regulating valve opening command, high pressure feedwater bypass regulation command and boiler fuel quantity command through the new CCS control system to regulate the extraction steam of the high pressure exhaust system and control the steam flow rate entering the high pressure exhaust system. S3. Under the regulation and control of the new CCS control system, the high-pressure exhaust system extracts steam generated by the heating system to obtain high-pressure exhaust. After being reheated by the heating system, the high-pressure exhaust enters the high-pressure exhaust system, the medium-pressure exhaust system and the low-pressure exhaust system in sequence to obtain low-pressure exhaust. S4. The low-pressure exhaust steam is condensed through the condensation circulation system and circulated to the heating system to form a thermodynamic cycle.

[0015] Optionally, the control method based on the feedwater bypass participating in the load change response of the thermal power unit also includes: When the thermal power unit is connected to the grid, the design main steam pressure command is the pressure of the downslope curve corresponding to the actual load of the thermal power unit, and the design turbine power command is the grid load. Among them, when the grid load is higher than the actual turbine power command and the actual main steam pressure command is lower than the pressure of the downward pressure curve corresponding to the actual load of the thermal power unit, the new CCS control system increases the turbine regulating valve opening command and the high-pressure feedwater bypass regulating valve opening command, and reduces the extraction steam of the high-pressure exhaust system. When the grid load is lower than the pressure of the downslope curve corresponding to the actual load of the thermal power unit and the actual main steam pressure command is higher than the design main steam pressure command, the new CCS control system reduces the boiler fuel quantity command, lowers the actual main steam pressure command, reduces the steam flow into the high-pressure exhaust system, and closes the opening command of the high-pressure heater feedwater bypass regulating valve. Compared with existing technologies, the control system and method for participating in the load change response of thermal power units based on feedwater bypass provided in this application are mainly based on the technical route of deep utilization of turbine energy storage. It uses a command system to input the design turbine power command and design main steam pressure command to the new CCS control system, and inputs the actual turbine power command and actual main steam pressure command to the thermal power unit system. The new CCS control system outputs and controls the turbine regulating valve opening command, the high-pressure heater feedwater bypass regulation command, and the boiler fuel quantity command to regulate the extraction steam of the high-pressure exhaust system and control the steam flow entering the high-pressure exhaust system. This can reduce the fluctuation of the boiler fuel quantity command, achieve stable control of the main steam pressure, and cause less damage to the heater.

[0016] The control system and method based on feedwater bypass participation in the load change response of thermal power units in this application utilize the heat storage characteristics of feedwater heaters and add the high-pressure heater feedwater bypass regulation command as an input variable. This transforms the traditional "two-input, two-output" coordinated control model structure of the thermal power unit load change response control system into a "three-input, two-output" form. The advanced coordinated control system employs different feedforward control techniques, enabling the thermal power unit to have a flexible steam extraction system after the grid load command changes. This allows for rapid coordination of the heating system and turbine energy, thereby improving the thermal power unit's ability to quickly change loads.

[0017] The novel CCS control system includes a traditional CCS control system and a high-pressure water supply bypass throttling control system. The conventional CCS control system includes a turbine regulating valve opening command module and a boiler fuel quantity command module. The turbine regulating valve opening command module is used to output turbine regulating valve opening commands to control the steam flow rate entering the high-pressure exhaust system; the boiler fuel quantity command module is used to output boiler fuel quantity commands to control the amount of steam generated by the heating system. The high-pressure heater feedwater bypass throttling control system is connected to the high-pressure exhaust system. It includes a high-pressure heater feedwater bypass adjustment command module, which outputs high-pressure heater feedwater bypass adjustment commands to adjust the steam extraction rate of feedwater in the high-pressure exhaust system. By adding high-pressure heater feedwater bypass adjustment commands through the high-pressure heater feedwater bypass adjustment command module, the traditional "two-inlet, two-outlet" coordinated control model structure can be transformed into a "three-inlet, two-outlet" form.

[0018] The high-pressure feedwater bypass throttling control system also includes a load signal processing module, which is used to process the design turbine power command to obtain low-frequency and high-frequency signals of the load command. The control method of the turbine regulating valve opening command module is as follows: The low-frequency load command signal and the turbine power deviation command are used as feedforward compensation and superimposed on the main steam pressure deviation command. Under the action of amplitude and speed limiting, the turbine regulating valve opening command is output to control the steam flow into the high-pressure exhaust system, thereby controlling the output power of the thermal power unit. This structure uses the low-frequency load command signal instead of the traditional load command as the feedforward compensation signal, which can reduce the fluctuation of fuel quantity command and achieve stable control of main steam pressure.

[0019] The control method of the high-pressure water supply bypass regulating module is as follows: By combining the turbine power command and the main steam pressure deviation command, a high-frequency signal of the load command is extracted. Under the action of amplitude and speed limiting, the high-frequency signal and the main steam pressure deviation command output a high-pressure heater feedwater bypass regulation command to regulate the steam extraction rate of the feedwater in the high-pressure exhaust system. Based on the deep utilization technology of turbine energy storage, this structure uses the combination of high-frequency signal and main steam pressure deviation command to jointly control the turbine extraction steam flow rate or the turbine extraction heater feedwater bypass flow rate, thereby improving the control accuracy. Attached Figure Description

[0020] Figure 1 This is a schematic diagram of the control system based on the feedwater bypass participating in the load change response of the thermal power unit according to an embodiment of this application; Figure 2 This is a schematic diagram of the structure of a novel CCS control system in a control system based on a feedwater bypass participating in the load change response of a thermal power unit, according to an embodiment of this application. Detailed Implementation

[0021] The embodiments of this application are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application.

[0022] The following describes, with reference to the accompanying drawings, a control system and method based on water supply bypass participating in the load change response of thermal power units according to embodiments of this application.

[0023] The following is combined with Figure 1 This application provides a detailed description of the control system based on the feedwater bypass participating in the load change response of the thermal power unit. Figure 1 This is a schematic diagram of the control system based on the water supply bypass participating in the load change response of the thermal power unit, according to an embodiment of this application.

[0024] In this embodiment, as Figure 1 and Figure 2As shown, the control system based on the feedwater bypass participating in the load change response of the thermal power unit, namely the boiler-turbine coordination system, includes the thermal power unit system, the command system and the new CCS control system. The thermal power unit system includes the heating system, the multi-stage pressure exhaust system and the condensing circulation system.

[0025] Specifically, the heating system is used to heat and generate steam. This heating system includes a fuel system and a boiler; the fuel system acts on the boiler to produce superheated steam. The multi-stage pressure exhaust system includes a high-pressure exhaust system, a medium-pressure exhaust system, and a low-pressure exhaust system connected in sequence. The high-pressure exhaust system, under the regulation and control of the new CCS control system, extracts steam generated by the heating system to obtain high-pressure exhaust steam. After being reheated by the heating system, the high-pressure exhaust steam sequentially enters the high-pressure exhaust system, the medium-pressure exhaust system, and the low-pressure exhaust system for extraction to obtain low-pressure exhaust steam.

[0026] The condensing cycle system condenses the low-pressure exhaust steam and circulates it to the heating system to form a thermodynamic cycle. The command system inputs design turbine power and design main steam pressure commands to the new CCS control system, and actual turbine power and actual main steam pressure commands to the thermal power unit system. The new CCS control system outputs and controls turbine regulating valve opening commands, high-pressure heater feedwater bypass regulation commands, and boiler fuel quantity commands to regulate the extraction steam volume of the high-pressure exhaust system and control the inlet steam flow into the high-pressure exhaust system. Here, the turbine power design value corresponding to the design turbine power command is... N T0 The design value of the main steam pressure corresponding to the design main steam pressure command is... p m0 The actual turbine power command corresponds to the actual turbine power of the turbine. N T The actual main steam pressure corresponding to the actual main steam pressure command is: p m .

[0027] Among them, the control system based on the feedwater bypass participating in the load change response of the thermal power unit also includes the boiler-turbine protection system, which is set at the command output end of the new CCS control system to further adjust and control the variables of the parameters corresponding to each command.

[0028] Specifically, such as Figure 2As shown, the new CCS control system includes a traditional CCS control system and a high-pressure heater feedwater bypass throttling control system. The traditional CCS control system includes a turbine regulating valve opening command module and a boiler fuel quantity command module. The turbine regulating valve opening command module is used to output turbine regulating valve opening commands to control the steam flow rate entering the high-pressure exhaust system. The boiler fuel quantity command module is used to output boiler fuel quantity commands to control the amount of steam generated by the heating system. The high-pressure heater feedwater bypass throttling control system is connected to the high-pressure exhaust system and includes a high-pressure heater feedwater bypass regulation command module, which is used to output high-pressure heater feedwater bypass regulation commands to regulate the amount of steam extracted by feedwater in the high-pressure exhaust system.

[0029] In a specific embodiment of this application, such as Figure 1 As shown, the control system based on the feedwater bypass participating in the load change response of the thermal power unit also includes the generator, and a multi-stage pressure exhaust system. The high-pressure exhaust system, under the regulation and control of the new CCS control system, extracts steam generated by the heating system to obtain high-pressure exhaust, and transfers the reheated steam generated by the high-pressure exhaust from the heating system to the medium-pressure exhaust system. The medium-pressure exhaust system extracts reheated steam at medium pressure to obtain medium-pressure exhaust. The low-pressure exhaust system extracts medium-pressure exhaust at low pressure to obtain low-pressure exhaust. The high-pressure exhaust system includes a high-pressure cylinder (HP), a first-stage extraction module, and a second-stage extraction module. The high-pressure heater feedwater bypass throttling control system is connected to the first-stage extraction module, and a high-pressure heater feedwater bypass regulating valve is installed between the first-stage and second-stage extraction modules.

[0030] Specifically, the high-pressure cylinder has two stages of steam extraction, namely, the first stage steam extraction module and the second stage steam extraction module are respectively the No. 7 high-pressure heater (GJ7) and the No. 6 high-pressure heater (GJ6). A high-pressure heater feedwater bypass throttling control system is added at the No. 7 high-pressure heater (GJ7). A high-pressure heater feedwater bypass regulating valve is added between the outlet of the No. 6 high-pressure heater (GJ6) and the outlet of the No. 7 high-pressure heater (GJ7) to regulate the amount of steam extracted by the feedwater in the No. 7 high-pressure heater (GJ7). That is, the superheated steam at the boiler outlet enters the high-pressure cylinder (HP) under the action of the main steam valve to expand and do work, and realizes the regulation of the main steam's work capacity in the high-pressure cylinder.

[0031] The intermediate-pressure exhaust system includes an intermediate-pressure cylinder (IP), a three-stage extraction module, a four-stage extraction module, and a five-stage extraction module. The three-stage, four-stage, and five-stage extraction modules are respectively the No. 5 high-pressure heater (GJ5), the deaerator (CY), and the No. 3 low-pressure heater (DJ3). That is, the high-pressure exhaust steam from the aforementioned high-pressure cylinder re-enters the boiler and is converted into reheat steam. The reheat steam then enters the intermediate-pressure cylinder, expands, and performs work to produce intermediate-pressure exhaust steam.

[0032] The low-pressure exhaust system includes a low-pressure cylinder (2FLP), a six-stage extraction module, and a seven-stage extraction module. The six-stage extraction module and the seven-stage extraction module are respectively the No. 2 low-pressure heater (DJ2) and the No. 1 low-pressure heater (DJ1). The aforementioned medium-pressure exhaust steam enters the low-pressure cylinder, expands, and performs work to obtain low-pressure exhaust steam.

[0033] The condensing cycle system includes a condenser, a shaft seal heater, and a circulation system. The exhaust steam from the low-pressure cylinder enters the condenser for condensation. The condensate then passes sequentially through the shaft seal heater, the low-pressure heater, the deaerator, and the high-pressure heater before finally being sent to the boiler to complete the entire thermodynamic cycle.

[0034] In one possible implementation of this application embodiment, the command system includes a main steam pressure deviation command and a turbine power deviation command. The main steam pressure deviation command is the difference between the designed main steam pressure command and the actual main steam pressure command; the turbine power deviation command is the difference between the designed turbine power command and the actual turbine power command. The high-pressure heater feedwater bypass throttling control system also includes a load signal processing module, which processes the designed turbine power command to obtain low-frequency and high-frequency signals of the load command.

[0035] The control method of the turbine regulating valve opening command module is as follows: the low-frequency signal of the load command and the turbine power deviation command are used as feedforward compensation and superimposed on the main steam pressure deviation command. Under the action of amplitude limiting and speed limiting, the turbine regulating valve opening command is output to control the steam flow into the high-pressure exhaust system, thereby controlling the output power of the thermal power unit. Specifically, the control method of the turbine regulating valve opening command module is as follows: the low-frequency signal of the load command, after passing through the proportional coefficient P4 in the thermal power unit system, is used as feedforward compensation and superimposed on the main steam pressure deviation command controlled by PI1. Under the action of amplitude limiting and speed limiting, the turbine regulating valve opening command is output. u c It controls the steam flow rate entering the high-pressure exhaust system, thereby controlling the output power of the thermal power unit.

[0036] The boiler fuel quantity command module operates as follows: The turbine power deviation command, combined with the main steam pressure deviation command, serves as feedforward compensation. Under amplitude and speed limiting effects, it outputs a boiler fuel quantity command to control the amount of steam generated by the heating system, thereby controlling the steam flow rate entering the high-pressure exhaust system. Specifically, the boiler fuel quantity command module operates as follows: Under PI2 control, the turbine power deviation command, combined with the main steam pressure deviation command, serves as feedforward compensation. Under amplitude and speed limiting effects, it outputs a boiler fuel quantity command. u m By controlling the combustion of the boiler, the evaporation rate of the boiler can be controlled, thereby controlling the steam flow rate entering the high-pressure exhaust system.

[0037] The control method of the high-pressure heater feedwater bypass regulating module is as follows: Combining the design turbine power command and the main steam pressure deviation command, the high-frequency signal of the load command is extracted. Under the action of amplitude limiting and speed limiting, the high-frequency signal and the main steam pressure deviation command output the high-pressure heater feedwater bypass regulating command to regulate the steam extraction rate of feedwater in the high-pressure exhaust system. Specifically, the control method of the high-pressure heater feedwater bypass regulating module is as follows: the input signals to the high-pressure heater feedwater bypass throttling control system are the design turbine power command and the main steam pressure deviation command, and the output is the high-pressure heater feedwater bypass regulating valve opening command. The high-pressure heater feedwater bypass throttling control system utilizes the concept of multi-scale signal decomposition to extract high-frequency and low-frequency signals from the load command. The high-frequency signal and the main steam pressure deviation signal are controlled by P3 and PI3 respectively. Under the action of amplitude limiting and speed limiting links, they jointly output the opening command of the high-pressure heater feedwater bypass regulating valve. This is because the No. 7 high-pressure feedwater heater has a significant impact on the thermal power unit. When the feedwater flow through the No. 7 high-pressure feedwater heater increases, the steam extraction volume increases, thereby achieving the purpose of controlling the unit's output power. Therefore, the opening command of the No. 7 high-pressure heater inlet regulating valve of the turbine is used as the control variable.

[0038] Using the above-described control system based on feedwater bypass participation in the variable load response of thermal power units, this invention also provides a control method based on feedwater bypass participation in the variable load response of thermal power units. This control method based on feedwater bypass participation in the variable load response of thermal power units includes the following steps: S1. Steam is generated by a heating system; S2. Input the design turbine power command and design main steam pressure command to the new CCS control system through the command system, and input the actual turbine power command and actual main steam pressure command to the thermal power unit system; output and control the turbine regulating valve opening command, high pressure feedwater bypass regulation command and boiler fuel quantity command through the new CCS control system to regulate the extraction steam of the high pressure exhaust system and control the steam flow rate entering the high pressure exhaust system. S3. Under the regulation and control of the new CCS control system, the high-pressure exhaust system extracts steam generated by the heating system to obtain high-pressure exhaust. After being reheated by the heating system, the high-pressure exhaust enters the high-pressure exhaust system, the medium-pressure exhaust system and the low-pressure exhaust system in sequence to obtain low-pressure exhaust. S4. The low-pressure exhaust steam is condensed through the condensation circulation system and circulated to the heating system to form a thermodynamic cycle.

[0039] The control method based on feedwater bypass participating in the load change response of thermal power units also includes: under grid-connected state, designing the main steam pressure command as the pressure of the sliding pressure curve corresponding to the actual load of the thermal power unit, and designing the turbine power command as the grid load. Among them, when the grid load is higher than the actual turbine power command and the actual main steam pressure command is lower than the pressure of the downward pressure curve corresponding to the actual load of the thermal power unit, the new CCS control system increases the turbine regulating valve opening command and the high-pressure feedwater bypass regulating valve opening command, and reduces the extraction steam of the high-pressure exhaust system. When the grid load is lower than the pressure of the downslope curve corresponding to the actual load of the thermal power unit and the actual main steam pressure command is higher than the design main steam pressure command, the new CCS control system reduces the boiler fuel quantity command, lowers the actual main steam pressure command, reduces the steam flow into the high-pressure exhaust system, and closes the opening command of the high-pressure heater feedwater bypass regulating valve.

[0040] Specifically, when considering grid connection of thermal power units, p m0 This can be considered as the pressure of the downslope 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... N T At that time, if the actual main steam pressure p m The pressure is lower than the pressure curve corresponding to the actual load of the unit. Combined with the turbine power deviation command, the new CCS control system will increase the turbine regulating valve opening command to improve the output power of the thermal power unit. In addition, in the high-pressure heater feedwater bypass throttling control system, the high-pressure heater feedwater bypass regulating valve opening command will be increased to reduce the inlet water flow into the No. 7 high-pressure heater. Based on energy and mass balance, this will reduce the extraction of steam from the high-pressure cylinder, increase the load response capability of the generator unit, and enable it to respond quickly to the increase in grid load. After the adjustment is completed, the high-pressure heater feedwater bypass regulating valve will be closed again. Conversely, when the grid load is lower than the pressure of the downward pressure curve corresponding to the actual load of the thermal power unit and the actual main steam pressure command is higher than the design main steam pressure command, in response to the reduction in grid load, the new CCS control system reduces the boiler fuel quantity command, lowers the actual main steam pressure command, reduces the steam inlet flow of the high-pressure cylinder, and closes the opening command of the high-pressure heater feedwater bypass regulating valve. This increases the inlet water flow into the No. 7 high-pressure heater, further accelerating the extraction steam flow and reducing the work flow in the high-pressure cylinder. After the response is completed, the opening of the No. 7 high-pressure heater steam inlet regulating valve is restored, thus accelerating the response speed of the thermal power unit to the electrical load.

[0041] Here, those skilled in the art will understand that the specific operations of each step in the above-described control method based on the participation of the feedwater bypass in the load change response of the thermal power unit have been referenced above. Figures 1 to 2 The description of the control system based on the water supply bypass participating in the load change response of the thermal power unit has been described in detail, therefore, its repeated description will be omitted.

[0042] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. The scope of patent protection of the present invention shall be determined by the claims. Similarly, any equivalent structural changes made based on the description and drawings of the present invention shall also be included within the scope of protection of the present invention.

Claims

1. A control system based on feedwater bypass participating in the load change response of a thermal power unit, characterized in that, include: The thermal power unit system, command system, and new CCS control system, wherein the thermal power unit system includes a heating system, a multi-stage pressure exhaust system, and a condensing cycle system; The heating system is used to heat and generate steam; The multi-stage pressure exhaust system includes a high-pressure exhaust system, a medium-pressure exhaust system, and a low-pressure exhaust system connected in sequence. The high-pressure exhaust system is used to extract steam generated by the heating system under the regulation and control of the new CCS control system to obtain high-pressure exhaust steam. After being reheated by the heating system, the high-pressure exhaust steam enters the high-pressure exhaust system, the medium-pressure exhaust system, and the low-pressure exhaust system in sequence for extraction to obtain low-pressure exhaust steam. The condensation cycle system is used to condense the low-pressure exhaust steam and circulate it to the heating system to form a thermodynamic cycle. The command system is used to input design turbine power commands and design main steam pressure commands to the new CCS control system, and to input actual turbine power commands and actual main steam pressure commands to the thermal power unit system. The novel CCS control system is used to output and control the turbine regulating valve opening command, the high-pressure feedwater bypass regulation command, and the boiler fuel quantity command to regulate the extraction steam volume of the high-pressure exhaust system and control the steam inlet flow into the high-pressure exhaust system.

2. The control system based on feedwater bypass participating in the load change response of thermal power units according to claim 1, characterized in that, The novel CCS control system includes a traditional CCS control system and a high-pressure water supply bypass throttling control system. The conventional CCS control system includes a turbine regulating valve opening command module and a boiler fuel quantity command module. The turbine regulating valve opening command module is used to output turbine regulating valve opening commands to control the steam flow rate entering the high-pressure exhaust system; the boiler fuel quantity command module is used to output boiler fuel quantity commands to control the amount of steam generated by the heating system. The high-pressure heater feedwater bypass throttling control system is connected to the high-pressure exhaust system. It includes a high-pressure heater feedwater bypass adjustment command module, which is used to output high-pressure heater feedwater bypass adjustment commands to adjust the amount of steam extracted by the feedwater in the high-pressure exhaust system.

3. The control system based on feedwater bypass participating in the load change response of thermal power units according to claim 2, characterized in that, The command system includes a main steam pressure deviation command and a turbine power deviation command. The main steam pressure deviation command is the difference between the designed main steam pressure command and the actual main steam pressure command; the turbine power deviation command is the difference between the designed turbine power command and the actual turbine power command.

4. The control system based on feedwater bypass participating in the load change response of thermal power units according to claim 3, characterized in that, The high-pressure feedwater bypass throttling control system also includes a load signal processing module, which is used to process the design turbine power command to obtain low-frequency and high-frequency signals of the load command. The control method of the turbine regulating valve opening command module is as follows: The low-frequency signal of the load command and the turbine power deviation command are used as feedforward compensation and are superimposed on the main steam pressure deviation command. Under the action of amplitude and speed limiting, the turbine regulating valve opening command is output to control the steam flow into the high-pressure exhaust system, thereby controlling the output power of the thermal power unit.

5. The control system based on feedwater bypass participating in the load change response of thermal power units according to claim 4, characterized in that, The control method of the boiler fuel quantity instruction module is as follows: The turbine power deviation command, combined with the main steam pressure deviation command, serves as feedforward compensation. Under the effects of amplitude and speed limiting, the output furnace fuel quantity command controls the amount of steam generated by the heating system, thereby controlling the steam flow rate entering the high-pressure exhaust system.

6. The control system based on feedwater bypass participating in the load change response of thermal power units according to claim 4, characterized in that, The control method of the high-pressure water supply bypass regulating module is as follows: By combining the turbine power command and the main steam pressure deviation command, the high-frequency signal of the load command is extracted. Under the action of amplitude limiting and speed limiting, the high-frequency signal and the main steam pressure deviation command output the high-pressure heater feedwater bypass regulation command to regulate the steam extraction rate of feedwater in the high-pressure exhaust system.

7. The control system based on feedwater bypass participating in the load change response of thermal power units according to claim 2, characterized in that, The high-pressure exhaust system includes a high-pressure cylinder, a first-stage extraction module, and a second-stage extraction module. The high-pressure heater feedwater bypass throttling control system is connected to the first-stage extraction module, and a high-pressure heater feedwater bypass regulating valve is provided between the first-stage extraction module and the second-stage extraction module.

8. The control system based on feedwater bypass participating in the load change response of thermal power units according to claim 2, characterized in that, In the multi-stage pressure exhaust system, the high-pressure exhaust system is used to extract steam generated by the heating system under the regulation and control of the new CCS control system to obtain high-pressure exhaust steam, and to transfer the reheated steam generated by the high-pressure exhaust steam of the heating system to the medium-pressure exhaust system; the medium-pressure exhaust system is used to extract reheated steam at medium pressure to obtain medium-pressure exhaust steam; and the low-pressure exhaust system is used to extract medium-pressure exhaust steam at low pressure to obtain low-pressure exhaust steam.

9. A control method based on feedwater bypass participating in the load change response of thermal power units, characterized in that, The control system based on the feedwater bypass participating in the load change response of the thermal power unit as described in any one of claims 1-8 includes the following steps: S1. Steam is generated by a heating system; S2. Input the design turbine power command and design main steam pressure command to the new CCS control system through the command system, and input the actual turbine power command and actual main steam pressure command to the thermal power unit system; output and control the turbine regulating valve opening command, high pressure feedwater bypass regulation command and boiler fuel quantity command through the new CCS control system to regulate the extraction steam of the high pressure exhaust system and control the steam flow rate entering the high pressure exhaust system. S3. Under the regulation and control of the new CCS control system, the high-pressure exhaust system extracts steam generated by the heating system to obtain high-pressure exhaust. After being reheated by the heating system, the high-pressure exhaust enters the high-pressure exhaust system, the medium-pressure exhaust system and the low-pressure exhaust system in sequence to obtain low-pressure exhaust. S4. The low-pressure exhaust steam is condensed through the condensation circulation system and circulated to the heating system to form a thermodynamic cycle.

10. The control method based on feedwater bypass participating in the load change response of thermal power units according to claim 9, characterized in that, Control methods based on feedwater bypass participation in the load change response of thermal power units also include: When the thermal power unit is connected to the grid, the design main steam pressure command is the pressure of the downslope curve corresponding to the actual load of the thermal power unit, and the design turbine power command is the grid load. Among them, when the grid load is higher than the actual turbine power command and the actual main steam pressure command is lower than the pressure of the downward pressure curve corresponding to the actual load of the thermal power unit, the new CCS control system increases the turbine regulating valve opening command and the high-pressure feedwater bypass regulating valve opening command, and reduces the extraction steam of the high-pressure exhaust system. When the grid load is lower than the pressure of the downslope curve corresponding to the actual load of the thermal power unit and the actual main steam pressure command is higher than the design main steam pressure command, the new CCS control system reduces the boiler fuel quantity command, lowers the actual main steam pressure command, reduces the steam flow into the high-pressure exhaust system, and closes the opening command of the high-pressure heater feedwater bypass regulating valve.

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