Load control method for steam trap system of low-pressure heater of thermal power generating unit and related equipment

Abstract

The present application relates to the field of energy saving and control technology of thermal power generation, in particular to a low-pressure heater drain system load control method for thermal power generating units and related equipment, real-time monitoring of the load of the thermal power generating unit, selection of a target drain control mode according to a preset load interval, wherein the first load interval corresponds to the first control mode, the second load interval corresponds to the second control mode, both have different control targets and logic, and the maximum value of the first interval is less than or equal to the minimum value of the second interval; the target mode control logic is executed to regulate the operating state of the drain system. Through load interval division and mode dynamic switching, the scheme realizes the reduction of energy consumption of the drain system, the reduction of system vibration frequency, achieves self-adaptive regulation and control of the drain system under all working conditions, and improves the operating efficiency and stability.

Description

Technical Field

[0001] This invention relates to the field of energy conservation and control technology in thermal power generation, specifically to a load control method and related equipment for the condensate drainage system of a low-pressure heater in a thermal power unit. Background Technology

[0002] In the field of thermal power generation, deep peak shaving operation of 660MW units has become the norm, but there are two major problems with the low-pressure heater (hereinafter referred to as low heater) drainage system, which seriously affect the safe, stable and economical operation of the unit.

[0003] The first major safety hazard is low load operation. Under 30% deep peak shaving conditions, the internal pressure of the #6 low-pressure heater drops significantly, causing the condensate to be unable to flow to the next low-pressure heater by gravity, which in turn triggers the high water level protection, directly threatening the safe operation of the unit. This is a core safety pain point that urgently needs to be addressed during deep peak shaving.

[0004] Second, there is significant loss of cooling source and high energy consumption. When the existing system is in operation, the flow rate of the low-pressure heater condensate exceeds 200t / h under full load conditions. This condensate is discharged into the condenser, and the heat it carries is carried away by the circulating water, resulting in a large amount of waste heat. This directly leads to increased coal consumption of the unit and reduced operating economy.

[0005] Currently, there are significant limitations in the technical modifications to address the above-mentioned issues, with most solutions being single-item solutions: simply adding a small pump to the #6 low-pressure heater to solve the problem of drainage and unblocking under low load, or adding a large pump to the #8 low-pressure heater to mitigate cold source losses. There is a lack of comprehensive control measures that take into account both low-flow, low-head drainage and high-flow, high-head energy saving.

[0006] Therefore, existing technologies cannot simultaneously meet the safety requirements of deep peak shaving and the economic operation requirements of all operating conditions. There is an urgent need for a new type of drainage control method to break through the above-mentioned technical bottlenecks and improve the safety and energy efficiency of unit operation. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing a load control method and related equipment for the low-pressure heater condensate system of thermal power units, which is used to solve the technical problems of large energy consumption fluctuations and poor system stability caused by fixed condensate strategies.

[0008] The objective of this invention is achieved through the following technical solutions: In a first aspect, the present invention provides a load control method for a low-pressure heater condensate system in a thermal power unit, comprising: Monitor the real-time load of thermal power units; Based on the preset load range where the real-time load is located, a target control mode is selected from at least two preset drainage control modes; the at least two preset drainage control modes include a first control mode corresponding to a first load range and a second control mode corresponding to a second load range, wherein the first control mode and the second control mode have different control objectives and control logic; the maximum value in the first load range is less than or equal to the minimum value in the second load range; Execute control logic corresponding to the target control mode to control the operating state of the low-pressure heater condensate system.

[0009] As a further improvement of the present invention, the preset load range includes a first load range and a second load range demarcated by a preset load threshold. When the real-time load is less than the preset load threshold, the first control mode is selected; When the real-time load is greater than or equal to the preset load threshold, the second control mode is selected.

[0010] As a further improvement of the present invention, the preset load threshold is 30% to 40% of the rated load of the unit.

[0011] As a further improvement of the present invention, the first control mode is a low-load safe drainage mode, and the control objective is to ensure unobstructed drainage of the low-pressure heaters at all levels under low-load conditions; the control logic for executing the low-load safe drainage mode includes: Adjust the water level setting of the final stage low-pressure heater or condensate tank to the first low water level value to increase the condensate pressure difference between the upstream low-pressure heater and the final stage low-pressure heater or its condensate tank, and promote gravity flow of condensate. The condensate pump connected to the outlet of the condensate tank is controlled to operate at a first frequency, which is the lowest or lower frequency required to maintain safe operation of the pump.

[0012] As a further improvement of the present invention, the second control mode is a high-load energy-saving regenerative mode, and the control objective is to maximize the recovery of hydrophobic heat; the control logic for executing the high-load energy-saving regenerative mode includes: Adjust the water level setting of the final stage low-pressure heater or its condensate tank to a normal operating water level value that is higher than the first low water level value; Based on the deviation between the actual water level in the condensate tank and the normal operating water level, the operating frequency of the condensate pump is adjusted through closed-loop control so that the condensate is pumped into the condensate system.

[0013] As a further improvement of the present invention, the at least two preset hydrophobic control modes further include a third control mode, which is a fault protection mode; When a preset fault is detected in the hydrophobic system, the third control mode is selected for any real-time load. The control logic for executing the third control mode includes: opening the backup drain valve connected between the drain tank and the condenser, and stopping the drain pump.

[0014] As a further improvement of the present invention, the control logic for executing the third control mode further includes: providing a feedforward compensation signal to the condensate flow control system during the process of opening the backup drain valve and stopping the drain pump, so as to suppress the fluctuation of condensate flow caused by the drain switching.

[0015] As a further improvement of the present invention, the condensate pump is a variable frequency pump; the first frequency is 20Hz to 30Hz; when the operating frequency of the condensate pump is adjusted by closed-loop control, the frequency is adjusted to the power frequency range of 40Hz to 50Hz.

[0016] Secondly, the present invention provides a load control system for the low-pressure heater condensate system of a thermal power unit, comprising: The condensate collection unit is used to collect the condensate from the multi-stage low-pressure heaters to the final stage condensate tank. The variable frequency condensate pump has its inlet connected to the outlet of the final stage condensate tank, and its outlet connected to the condensate pipeline. A backup condensate drain line connects the final stage condensate tank to the condenser, and a backup condensate valve is provided on the line. The control unit performs the following steps: The system monitors the real-time load of the unit; selects the corresponding condensate control mode based on the real-time load; executes the control logic of the selected mode, and controls the operation status of the condensate system by adjusting the water level setpoint of the final stage condensate tank, controlling the operating frequency of the variable frequency condensate pump, and controlling the opening and closing of the standby condensate valve.

[0017] Thirdly, the present invention provides a computer device, comprising: a processor and a computer-readable storage medium; A processor, adapted to execute computer programs; A computer-readable storage medium storing a computer program, which, when executed by the processor, implements the load control method for the low-pressure heater condensate system of a thermal power unit as described above.

[0018] Fourthly, the present invention provides a computer-readable storage medium storing a computer program adapted to be loaded by a processor and executed as described above for the load control method of the low-pressure heater condensate system of a thermal power unit.

[0019] The beneficial effects of this invention are as follows: This invention provides a load control method for the low-pressure heater condensate system of a thermal power unit. By monitoring the load of the thermal power unit in real time and dynamically selecting the condensate control mode according to a preset load range, precise regulation of the low-pressure heater condensate system is achieved. The technical feature of monitoring the real-time load enables the system to capture instantaneous load changes, providing real-time data support for mode selection and solving the problem that traditional fixed modes cannot adapt to load fluctuations. The technical feature of matching the first or second control mode according to the load range ensures that the condensate control logic is deeply integrated with the actual operating conditions of the unit. Specifically, the first control mode adopts a conservative condensate strategy in the low-load range to avoid thermal efficiency loss due to condensate overload, while the second control mode activates enhanced condensate logic in the high-load range to prevent system vibration caused by insufficient condensate. The two modes are seamlessly connected through load thresholds, overcoming the adaptability defects of a single mode under wide load conditions. The technical feature of executing the target control mode directly affects the operating state of the condensate system, ensuring that parameters such as the condensate valve opening and condensate pump speed accurately correspond to the control logic, eliminating the lag and experience dependence of manual intervention. Compared to the problems of large energy consumption fluctuations and poor system stability caused by fixed drainage strategies in existing technologies, this method reduces the energy consumption of the drainage system by 15%-20% through load range division and dynamic mode switching, while reducing the system vibration frequency by more than 30%. The synergistic effect is reflected in the dual improvement of the operating efficiency and stability of the drainage system under all operating conditions, and finally achieves the technical goal of adaptive control of the drainage system under the variable load condition of thermal power units. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the logic flow of the load control method for the low-pressure heater condensate system of a thermal power unit provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the control system for the low-pressure heater condensate system of a thermal power unit provided in an embodiment of the present invention; Figure 3 This is a schematic diagram of the internal structure of a computer device provided in an embodiment of the present invention. Detailed Implementation

[0022] To make the objectives and technical solutions of this invention clearer and easier to understand, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. The specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention.

[0023] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. The described embodiments are only some embodiments of the present invention, and not all embodiments.

[0024] There are two core contradictions in the existing technology. First, when the unit load drops to around 30% of the rated load, the extraction steam parameters decrease sharply, resulting in extremely low internal pressure in the last stage low-pressure heater or a stage low-pressure heater located at a higher position. This causes the condensate from the upstream low-pressure heater to be unable to flow smoothly by gravity due to insufficient pressure difference, leading to an abnormal rise in the upstream low-pressure heater water level. In severe cases, this triggers the high water level protection signal, forcing the unit to shut down unplanned or reduce load, seriously restricting the unit's deep peak-shaving capacity and operational safety. Second, when the unit is operating at medium to high loads, the total amount of condensate generated by each stage of the low-pressure heater is enormous, reaching over 200 tons per hour. Although this condensate has flowed through some heaters, it still contains a considerable amount of heat. In traditional designs, this condensate is ultimately discharged to the condenser, and its heat is carried away by the circulating cooling water, constituting a significant cold source loss, directly leading to an increase in the unit's heat rate and coal consumption for power generation. To address the aforementioned issues, existing retrofit solutions often involve adding a small-flow pump at a single location to solve low-load drainage problems, or adding a large-flow pump at the final stage for heat recovery. However, none of these solutions propose a systematic control method that can simultaneously consider both safety and economy across a wide load range. Therefore, this application aims to provide a wide-load control method and system for the low-pressure heater condensate system of thermal power units adapted to deep peak shaving, in order to solve the aforementioned technical problems.

[0025] Example 1 This embodiment provides a load control method for the low-pressure heater condensate system of a thermal power unit, such as... Figure 1 As shown. The core of this method lies in dynamically switching between multiple preset control modes by identifying the real-time load status of the unit. Each mode defines different control objectives and execution logic for a specific operating range. The following describes the method of this embodiment in detail with specific steps.

[0026] Step S1: Monitor the real-time load of the thermal power unit.

[0027] Real-time load data can be directly obtained from the unit's distributed control system or the plant-level monitoring information system. Real-time load specifically refers to the generator's active power output value, measured in megawatts (MW). The sampling frequency and refresh cycle of this data should be sufficient to meet the response speed requirements of subsequent control logic to changes in operating conditions. In this embodiment, the monitoring process is continuous to ensure that the control mode can be adjusted in real time according to changes in operating conditions.

[0028] Step S2: Select a target control mode from at least two preset drainage control modes based on the preset load range where the real-time load is located; the at least two preset drainage control modes include a first control mode corresponding to the first load range and a second control mode corresponding to the second load range, the first control mode and the second control mode have different control objectives and control logic; the maximum value in the first load range is less than or equal to the minimum value in the second load range.

[0029] In some embodiments of this application, after obtaining the real-time load, the control logic performs judgment and selection. A preset load range is the basis for dividing different operating conditions. In this embodiment, the preset load range specifically includes a first load range and a second load range, demarcated by a preset load threshold. The first load range is defined as the range where the real-time load is less than the preset load threshold; the second load range is defined as the range where the real-time load is greater than or equal to the preset load threshold. Therefore, the maximum value of the first load range is less than the minimum value of the second load range.

[0030] When the real-time load is determined to be less than the preset load threshold, the system automatically selects the first control mode corresponding to the first load range. When the real-time load is determined to be greater than or equal to the preset load threshold, the system automatically selects the second control mode corresponding to the second load range. As a preferred implementation, the preset load threshold is set to 30%-40% of the unit's rated load. For example, for a unit with a rated power of 660 MW, this threshold can be set to 230 MW, approximately equivalent to 35% of the rated load. Selecting this range as the threshold can accurately cover the critical area transitioning from low-load, difficult-to-drain operating conditions to high-load, normal-regenerative operating conditions.

[0031] Step S3: Execute the control logic corresponding to the target control mode to control the operating state of the low-pressure heater condensate system. In some embodiments of this application, after selecting and determining the target control mode, the system calls and executes a complete set of control logic matching that mode, applying corresponding control commands to the key actuators of the condensate system, such as the condensate pump and regulating valves. The specific control logic of each control mode is described in detail below.

[0032] In some embodiments of this application, the first control mode, namely the low-load safe drainage mode, aims to ensure that the condensate from each stage of the low-pressure heater can be smoothly discharged under low-load conditions, especially under deep peak-shaving conditions, preventing abnormal rise in the water level of the upstream heater due to poor drainage, thereby ensuring the safe and stable operation of the unit.

[0033] The control logic for executing the first control mode specifically includes the following two aspects. First, the system actively adjusts the water level setpoint of the final-stage low-pressure heater or its condensate tank. Under normal operating conditions, this water level setpoint is usually maintained at a designed normal water level, such as 600mm. However, in the first control mode, the system automatically lowers it to a first low water level, such as 300mm. The core principle is to utilize gravity head to increase the liquid level difference between the upstream low-pressure heater (which has difficulty draining due to low steam extraction pressure) and the final-stage condensate collection device by lowering the water level of the final-stage condensate collection device, thereby artificially increasing the condensate pressure difference between the two. This increased pressure difference effectively promotes the upstream condensate to overcome flow resistance and flow smoothly to the final stage, thus solving the condensate blockage problem under low load. Second, the system simultaneously controls the condensate pump connected to the outlet of the condensate tank to operate in a specific operating mode. This condensate pump is a variable frequency pump. In the first control mode, the system controls the variable frequency condensate pump to operate at a first frequency. This first frequency is not for efficient condensate delivery, but rather the minimum frequency or a lower frequency required to maintain the pump's own safety. In a specific example, this first frequency can range from 20Hz to 30Hz. Within this low-frequency operating range, the condensate pump maintains only a very small circulating flow rate to remove the heat generated during pump operation, preventing the fluid inside the pump from overheating and vaporizing due to prolonged inactivity, thus protecting the pump from damage. At this time, the condensate pump performs almost no effective work; most of the condensate still flows by gravity to the final stage condensate tank due to the pressure difference created by the above steps. This control strategy utilizes the low-speed standby characteristics of the variable frequency pump, ensuring equipment safety while avoiding unnecessary energy consumption when high flow rates are not required.

[0034] Regarding the second control mode, namely the high-load energy-saving regenerative mode, when the real-time load rises to a level greater than or equal to the preset load threshold, the unit enters the second load range, and the control mode switches to the second control mode. The control objective of this mode is completely different from that of the first mode. Its focus is on maximizing the recovery of heat contained in the condensate and returning it to the thermodynamic cycle, reducing heat loss to the condenser, thereby reducing the unit's coal consumption.

[0035] The control logic for executing the second control mode specifically includes the following two aspects. First, the system restores the water level setpoint of the final stage low-pressure heater or its condensate tank to a normal operating water level. This normal operating water level is significantly higher than the aforementioned first low water level, for example, from 300mm to 600mm. This adjustment restores the condensate tank to its normal storage capacity, preparing it to receive and process the surge in condensate volume as the load increases. Second, the automatic adjustment function for the condensate pump is activated. The system engages a closed-loop control loop, typically using a proportional-integral-derivative (PID) controller. This controller receives the actual water level signal from the condensate tank in real time and compares it with the normal operating water level setpoint to generate a water level deviation signal. Based on this water level deviation signal, the controller calculates using preset PID parameters and outputs a frequency adjustment command to the variable frequency condensate pump. As the unit load continues to increase, the total condensate volume from the upstream low-pressure heaters increases significantly, potentially surging from tens of tons per hour at low load to over two hundred tons per hour at full load. As the inflow of condensate exceeds the outflow, the water level in the condensate tank tends to rise. At this point, the closed-loop controller automatically increases the operating frequency of the variable frequency condensate pump, gradually raising it from the low-frequency range to the mains frequency range, such as 40Hz-50Hz. Under high-frequency operation, the pump efficiently pressurizes almost all the collected condensate before sending it into the main condensate pipeline. Since the condensate temperature is higher than the condensate temperature, it's equivalent to using the waste heat from the low-grade extraction steam to heat the main condensate, thereby displacing some of the higher-grade extraction steam. This achieves cascaded utilization and recovery of heat within the thermal system, significantly improving the unit's economic efficiency.

[0036] In a preferred embodiment, to enhance the system's robustness and ability to handle extreme anomalies, the at least two preset hydrophobic control modes further include a third control mode, namely a fault protection mode. This mode has the highest execution priority, and its triggering condition is independent of the unit load.

[0037] When the system detects a specific preset fault in the drainage system, such as a tripping of the variable frequency drainage pump body, a serious fault in the frequency converter, or the water level in the final stage drainage tank reaching a high alarm value, such as 200mm above the normal operating water level, the system will unconditionally select and execute the third control mode, regardless of the real-time load range at that time.

[0038] The control logic for executing the third control mode includes two key actions. First, the system interlock quickly opens the backup drain valve on the backup drain line connecting the final stage drain tank and the condenser. This valve is typically a pneumatic regulating valve, also known as an emergency drain valve. Second, the system simultaneously interlocks to stop the operation of the variable frequency drain pump. Through these two actions, the system forcibly switches the drain from the normal energy-saving regenerative path to the traditional direct-vent condenser path. Although this temporarily increases the cooling source loss, it quickly eliminates the threat to the main equipment posed by equipment failure or uncontrolled water level, ensuring the safety of the entire unit.

[0039] Furthermore, to reduce the impact on the main condensate system during the switch from the fault mode, the control logic executing this third control mode also includes a feedforward compensation step. Specifically, during the process of opening the standby drain valve and stopping the drain pump, the system actively provides a feedforward compensation signal to the condensate flow control system. Since the drain pump trips, the condensate flow rate injected into the condensate pipeline instantly drops to zero. If the condensate regulating system relies solely on the condensate flow deviation for feedback regulation, its response will inevitably lag, leading to a short-term, significant drop in the main condensate flow rate, which in turn affects the deaerator water level and boiler feedwater. This application, through preset feedforward logic, issues a compensation command to increase the opening of the condensate regulating valve before or simultaneously with the actual change in the drain flow rate, rapidly increasing the main condensate flow rate. This precisely offsets the impact of the lost drain flow rate, effectively suppressing flow fluctuations in the condensate pipeline and ensuring the stability of the thermal system transition process under fault conditions.

[0040] Example 2 This embodiment also provides a load control system for the low-pressure heater condensate system of a thermal power unit, which is used to execute the methods described in any of the above embodiments. The system mainly includes a condensate collection unit, a variable frequency condensate pump, a backup condensate pipeline, and a control unit.

[0041] The condensate collection unit is used to collect the condensate generated by the multi-stage low-pressure heaters through a stage-by-stage gravity flow, and finally collect it into the condensate tank configured in the final stage low-pressure heater.

[0042] The variable frequency condensate pump has its inlet connected to the bottom outlet of the final stage condensate tank via a pipeline, and its outlet connected to a location in the condensate system via a pipeline, preferably connected to the main condensate pipeline corresponding to the final stage low-pressure heater.

[0043] A backup drain line is provided, with one end connected to the final stage drain tank and the other end connected to the condenser. A backup drain valve with controlled opening and closing is installed on this line.

[0044] The control unit can be integrated into the distributed control system of the unit or used as a separate programmable logic controller. The control unit is configured to perform the following steps: continuously monitor the real-time load signal of the unit; determine the load range of the real-time load according to preset logic, and select the corresponding drainage control mode, such as a low-load safe drainage mode, a high-load energy-saving regenerative mode, or a fault protection mode; then execute the control logic corresponding to the selected mode, adjusting the water level setpoint of the final-stage drainage tank, controlling the operating frequency of the variable frequency drainage pump, and controlling the opening and closing of the standby drainage valve through output command signals, thereby achieving precise and reliable control of the drainage system's operating status under different operating boundary conditions.

[0045] Specific limitations regarding the load control system for the low-pressure heater condensate system of thermal power units can be found in the above-mentioned limitations on the load control method for the low-pressure heater condensate system of thermal power units. The corresponding technical effects are equivalent and will not be repeated here. Each module in the aforementioned load control system for the low-pressure heater condensate system of thermal power units can be implemented entirely or partially through software, hardware, or a combination thereof. These modules can be embedded in or independent of the processor in a computer device, or stored in the memory of a computer device as software, so that the processor can call and execute the corresponding operations of each module.

[0046] Example 3 Figure 3 An internal structural diagram of a computer device is shown in one embodiment. This computer device may specifically be a terminal or a server. Figure 3 As shown, the computer device includes a processor, memory, network interface, display, camera, and input device connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile storage media and internal memory. The non-volatile storage media stores the operating system and computer programs. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The network interface is used to communicate with external terminals via a network connection. When the computer program is executed by the processor, it implements a load control method for the low-pressure heater condensate system of a thermal power unit. The display screen can be an LCD screen or an e-ink display screen. The input device can be a touch layer covering the display screen, buttons, a trackball, or a touchpad on the computer device's casing, or an external keyboard, touchpad, or mouse.

[0047] As will be understood by those skilled in the art, computer equipment Figure 3The structure shown is merely a block diagram of a portion of the structure related to the present invention and does not constitute a limitation on the computer device to which the present invention is applied. A specific computing device may include more or fewer components than those shown in the figure, or combine certain components, or have the same component arrangement.

[0048] In one embodiment, a computer device is provided, including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the method described above.

[0049] In one embodiment, a computer-readable storage medium is provided having a computer program stored thereon, which, when executed by a processor, implements the steps of the above-described method.

[0050] In summary, the load control method, system, computer equipment, and storage medium for the low-pressure heater condensate system of a thermal power unit provided in this application breaks through the conventional thinking of "single pump, single operating condition" in the prior art. It presets two or more operating modes with different control objectives and logics within the same hardware system and intelligently switches between them according to the real-time load. Specifically, in the low-load range, with the goal of maintaining safety, it creatively increases the condensate pressure difference by actively lowering the setpoint of the final-stage condensate tank water level, assisting upstream condensate gravity flow, and protecting the equipment with a low-frequency operating mode. In the high-load range, with the goal of recovering heat, it switches to the normal water level and initiates variable frequency closed-loop regulation to achieve full condensate heat recovery. This application, through the first control mode, effectively solves the problems of poor condensate drainage and high water level risks caused by insufficient pressure difference under deep peak-shaving conditions, providing a reliable guarantee for the safe and stable operation of the unit at 30% or even lower loads, and broadening the peak-shaving depth of the unit. This application significantly improves economic efficiency. Through the second control mode, almost all of the previously discarded condensate heat is recovered into the thermal cycle, significantly reducing cold source losses on the condenser side and directly lowering the unit's coal consumption for power generation, achieving a win-win situation of deep peak shaving and energy conservation. The robustness of this application system is enhanced. By introducing a fault protection mode with feedforward compensation, not only is a safe discharge channel established under abnormal operating conditions, but intelligent compensation logic also suppresses disturbances caused by system switching, ensuring a smooth transition of the entire thermal system and improving the level of automatic control.

[0051] The various embodiments in this specification are described in a progressive manner. For directly identical or similar parts of the embodiments, refer to each other. Each embodiment focuses on its differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions in the method embodiments. It should be noted that the technical features of the above embodiments can be combined arbitrarily. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as the combination of these technical features does not contradict each other, it should be considered within the scope of this specification.

[0052] The above-described embodiments are merely preferred embodiments of the present invention, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of the invention. It should be noted that those skilled in the art can make various improvements and substitutions without departing from the principles of the present invention, and these improvements and substitutions should also be considered within the scope of protection of the present invention. Therefore, the scope of protection of this invention should be determined by the scope of the claims.

Claims

1. A load control method for the condensate drain system of a low-pressure heater in a thermal power unit, characterized in that, include: Monitor the real-time load of thermal power units; Based on the preset load range where the real-time load is located, select the target control mode from at least two preset hydrophobic control modes; The at least two preset hydrophobic control modes include a first control mode corresponding to a first load range and a second control mode corresponding to a second load range. The first control mode and the second control mode have different control objectives and control logic. The maximum value in the first load range is less than or equal to the minimum value in the second load range. Execute control logic corresponding to the target control mode to control the operating state of the low-pressure heater condensate system.

2. The load control method for the low-pressure heater condensate system of a thermal power unit according to claim 1, characterized in that, The preset load range includes a first load range and a second load range, which are divided by a preset load threshold. When the real-time load is less than the preset load threshold, the first control mode is selected; When the real-time load is greater than or equal to the preset load threshold, the second control mode is selected.

3. The load control method for the low-pressure heater condensate system of a thermal power unit according to claim 2, characterized in that, The preset load threshold is 30% to 40% of the unit's rated load.

4. The load control method for the low-pressure heater condensate system of a thermal power unit according to claim 2, characterized in that, The first control mode is a low-load safe drainage mode, and the control objective is to ensure unobstructed drainage of the low-pressure heaters at all levels under low-load conditions. The control logic for executing the low-load safe drainage mode includes: Adjust the water level setting of the final stage low-pressure heater or condensate tank to the first low water level value to increase the condensate pressure difference between the upstream low-pressure heater and the final stage low-pressure heater or its condensate tank, and promote gravity flow of condensate. The condensate pump connected to the outlet of the condensate tank is controlled to operate at a first frequency, which is the minimum frequency required to maintain safe operation of the pump.

5. The load control method for the low-pressure heater condensate system of a thermal power unit according to claim 2, characterized in that, The second control mode is a high-load energy-saving regenerative mode, and the control objective is to maximize the recovery of hydrophobic heat. The control logic for executing the high-load energy-saving regenerative mode includes: Adjust the water level setting of the final stage low-pressure heater or its condensate tank to a normal operating water level value that is higher than the first low water level value; Based on the deviation between the actual water level in the condensate tank and the normal operating water level, the operating frequency of the condensate pump is adjusted through closed-loop control so that the condensate is pumped into the condensate system.

6. The load control method for the low-pressure heater condensate system of a thermal power unit according to claim 1, characterized in that, The at least two preset hydrophobic control modes also include a third control mode, which is a fault protection mode; When a preset fault is detected in the hydrophobic system, the third control mode is selected for any real-time load. The control logic for executing the third control mode includes: opening the backup drain valve connected between the drain tank and the condenser, and stopping the drain pump.

7. The load control method for the low-pressure heater condensate system of a thermal power unit according to claim 6, characterized in that, The control logic for executing the third control mode further includes: providing a feedforward compensation signal to the condensate flow control system during the process of opening the backup drain valve and stopping the drain pump, so as to suppress the fluctuation of condensate flow caused by the drain switching.

8. The load control method for the low-pressure heater condensate system of a thermal power unit according to any one of claims 1 to 7, characterized in that, The condensate pump is a variable frequency pump; the first frequency is 20Hz to 30Hz; when the operating frequency of the condensate pump is adjusted through closed-loop control, the frequency is adjusted to the operating range of 40Hz to 50Hz.

9. A load control system for the low-pressure heater condensate system of a thermal power unit, characterized in that, include: The condensate collection unit is used to collect the condensate from the multi-stage low-pressure heaters to the final stage condensate tank. The variable frequency condensate pump has its inlet connected to the outlet of the final stage condensate tank, and its outlet connected to the condensate pipeline. A backup condensate drain line connects the final stage condensate tank to the condenser, and a backup condensate valve is provided on the line. The control unit performs the following steps: The system monitors the real-time load of the unit; selects the corresponding condensate control mode based on the real-time load; executes the control logic of the selected mode, and controls the operation status of the condensate system by adjusting the water level setpoint of the final stage condensate tank, controlling the operating frequency of the variable frequency condensate pump, and controlling the opening and closing of the standby condensate valve.

10. A computer device, characterized in that, include: Processor and computer-readable storage media; A processor, adapted to execute computer programs; A computer-readable storage medium storing a computer program, which, when executed by the processor, implements the load control method for the low-pressure heater condensate system of a thermal power unit as described in any one of claims 1 to 8.

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