Control system for a thermal power generating unit

Abstract

This application proposes a control system for a thermal power generating unit, comprising: a fault diagnosis unit for determining whether the steam-driven feedwater pump has malfunctioned based on unit load control commands, the main feedwater flow rate of the steam-driven feedwater pump, the valve position value of the low-pressure valve, the valve position control command of the low-pressure valve, and the current month; a first control unit for tripping the coal mill and starting the plasma system after the steam-driven feedwater pump malfunctions; and a second control unit for determining the coal feed rate control command based on the superheat after the steam-driven feedwater pump malfunctions. This solution can not only promptly identify faults in the steam-driven feedwater pump but also ensure the safe and stable operation of the unit when the steam-driven feedwater pump malfunctions.

Description

Technical Field

[0001] This application relates to the field of intelligent control of thermal power generating units, and more particularly to a control system for thermal power generating units. Background Technology

[0002] To reduce the power consumption of generating units, thermal power generating units often use steam-driven feedwater pumps to supply water to the boiler. A steam-driven feedwater pump is a feedwater pump driven by a separate small steam turbine. This turbine draws steam from the extraction steam pipeline, uses the pressure difference of the steam supplied to the deaerator to do work, and drives the feedwater pump to supply water through the rotation of the turbine.

[0003] Typically, a failure in the steam-driven feedwater pump will cause the unit to shut down, severely impacting its normal operation. Therefore, ensuring the stable and safe operation of the unit under such abnormal conditions has become a current construction goal for thermal power generating units. Summary of the Invention

[0004] To address the aforementioned problems, this application provides a control system for a thermal power generator set.

[0005] According to one aspect of this application, a control system for a thermal power generating unit is provided, the thermal power generating unit being equipped with a steam-driven feedwater pump and an electric feedwater pump; the system includes:

[0006] The fault diagnosis unit is used to determine whether the steam-driven feedwater pump is malfunctioning based on the unit load control command, the main feedwater flow value of the steam-driven feedwater pump, the valve position value of the low-pressure valve, the valve position control command of the low-pressure valve, and the current month.

[0007] The first control unit is used to trip the coal mill and start the plasma system after the steam-driven feedwater pump fails.

[0008] The second control unit is used to determine the coal feed rate control command based on the superheat after the steam-driven feedwater pump fails.

[0009] In some embodiments of this application, the fault diagnosis unit includes: a subunit for determining the deviation of the unit load control command, a switch signal input module for tripping the steam-driven feedwater pump, a fault diagnosis subunit for insufficient output of the steam-driven feedwater pump, a fault output module for the steam-driven feedwater pump, a first OR module, and a first high limit module; wherein:

[0010] The steam-driven feedwater pump insufficient output fault diagnosis subunit is used to determine whether the steam-driven feedwater pump has insufficient output fault based on the main feedwater flow rate, the valve position value of the low-pressure valve, the valve position control command of the low-pressure valve, and the current month; the steam-driven feedwater pump insufficient output fault diagnosis subunit and the switch signal input module for the steam-driven feedwater pump trip are both connected to the input terminal of the first or module.

[0011] The unit load control command deviation determination subunit is used to output the corresponding unit load control command deviation according to the unit load command; the output terminal of the first OR module is connected to the input terminal of the unit load control command deviation determination subunit; the output terminal of the unit load control command deviation determination subunit is connected to the input terminal of the first high limit module; the output terminal of the first high limit module is connected to the steam-driven feedwater pump fault output module.

[0012] As one possible implementation, the deviation determination subunit for unit load control commands includes: an analog signal input module for unit load control commands, a first switching module, a first constant module, and a first subtraction module; wherein:

[0013] The output terminal of the first OR module is connected to the S terminal of the first switching module; the analog signal input module for unit load control commands is connected to the PV2 terminal of the first switching module; the first constant module is connected to the PV1 terminal of the first switching module; the output terminal of the first switching module and the analog signal input module for unit load control commands are both connected to the input terminal of the first subtraction module; the output terminal of the first subtraction module is connected to the first high limit module.

[0014] As another possible implementation, the steam pump fault diagnosis unit also includes a first low-limit module and a steam-driven feedwater pump fault reset module; wherein:

[0015] The output of the first subtraction module is connected to the input of the first low limit module; the output of the first low limit module is connected to the steam-driven feedwater pump fault reset module.

[0016] In some embodiments of this application, the first control unit includes: a switch signal input module indicating a fault in the steam-driven feedwater pump, a switch signal input module indicating that the fault monitoring function of the steam-driven feedwater pump is activated, a switch signal input module indicating that the fault in the steam-driven feedwater pump has been reset, a first AND module, a first NOT module, a second OR module, a first RS trigger module, and a control module for the continuous tripping of the coal mill and the start of the plasma system; wherein:

[0017] The switch signal input module for the faulty steam-driven feedwater pump and the switch signal input module for the activated steam-driven feedwater pump fault monitoring function are both connected to the input terminal of the first AND module; the switch signal input module for the activated steam-driven feedwater pump fault monitoring function is connected to the input terminal of the first NOT module; the output terminals of the switch signal input module for the reset steam-driven feedwater pump fault and the first NOT module are both connected to the input terminal of the second OR module; the output terminal of the first AND module is connected to the S terminal of the first RS trigger module; the output terminal of the second OR module is connected to the R terminal of the first RS trigger module; the DV terminal of the first RS trigger module is connected to the control module for the continuous tripping coal mill and the start of the plasma system.

[0018] In some embodiments of this application, the second control unit includes a superheat correction subunit, a switch signal input module for a faulty steam-driven feedwater pump, a second constant module, a second switching module, a second inertial module, and a coal feed rate control command output module for a faulty steam-driven feedwater pump; wherein:

[0019] The switch signal input module for a faulty steam-driven feedwater pump is connected to the S terminal of the second switching module; the superheat correction subunit is connected to the PV1 terminal of the second switching module; and the second constant module is connected to the PV2 terminal of the second switching module. The output terminal of the second switching module is connected to the input terminal of the second inertial module, and the output terminal of the second inertial module is connected to the coal feed rate control command output module when the steam-driven feedwater pump fails.

[0020] As one possible implementation, the superheat correction subunit includes: an analog signal input module for superheat, a first function module, a first inertia module, a second subtraction module, and a first addition module; wherein:

[0021] The analog signal input module for superheat is connected to the input terminals of the first function module and the first inertial module, respectively; the output terminals of the first function module and the first inertial module are both connected to the input terminal of the second subtraction module; the output terminals of the first function module and the second subtraction module are both connected to the input terminal of the first addition module; and the output terminal of the first addition module is connected to the PV1 terminal of the second switching module.

[0022] According to the control system of the thermal power generating unit of this application, a fault diagnosis unit determines whether the steam-driven feedwater pump is malfunctioning based on the unit load control command, the main feedwater flow rate of the steam-driven feedwater pump, the valve position value of the low-pressure valve, the valve position control command of the low-pressure valve, and the current month. Upon failure of the steam-driven feedwater pump, the first and second control units are connected to trip the coal mill and start the plasma system, while simultaneously adjusting the coal feed rate according to the superheat. This solution not only promptly identifies faults in the pneumatic feedwater pump but also ensures the safe and stable operation of the unit even when the steam-driven feedwater pump fails.

[0023] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0024] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0025] Figure 1 A structural block diagram of a control system for a thermal power generating unit provided in an embodiment of this application;

[0026] Figure 2This is a structural block diagram of a fault diagnosis unit according to an embodiment of this application;

[0027] Figure 3 This is a structural block diagram of a subunit for diagnosing insufficient output of a steam-driven feedwater pump, as described in an embodiment of this application.

[0028] Figure 4 This is a structural block diagram of a first control unit in an embodiment of this application;

[0029] Figure 5 This is a structural block diagram of a second control unit in an embodiment of this application. Detailed Implementation

[0030] 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.

[0031] It should be noted that, in order to reduce the power consumption of the unit, thermal power generating units mostly use steam-driven feedwater pumps to supply water to the boiler. The steam-driven feedwater pump is a feedwater pump driven by a separate small steam turbine. This turbine draws steam from the extraction steam pipeline, uses the pressure difference of the steam supplied to the deaerator to do work, and the rotation of the steam turbine replaces the feedwater pump to supply water.

[0032] Typically, a failure in the steam-driven feedwater pump will cause the unit to shut down, severely impacting its normal operation. Therefore, ensuring the stable and safe operation of the unit under such abnormal conditions has become a current construction goal for thermal power generating units.

[0033] To address the aforementioned problems, this application provides a control system for a thermal power generator set.

[0034] Figure 1 This is a structural block diagram of a control system for a thermal power generating unit provided in an embodiment of this application. It should be noted that the thermal power generating unit in this embodiment is equipped with an electric feedwater pump and a steam-driven feedwater pump. Figure 1 As shown, the system may include: a fault diagnosis unit 101, a first control unit 102, and a second control unit 103.

[0035] In some embodiments of this application, the fault diagnosis unit 101 is used to determine whether the steam-driven feedwater pump has malfunctioned based on the unit load control command, the main feedwater flow rate value of the steam-driven feedwater pump, the valve position value of the low-pressure valve, the valve position control command of the low-pressure valve, and the current month. The first control unit 102 is used to trip the coal mill and start the plasma system after the steam-driven feedwater pump malfunctions. The second control unit 103 is used to determine the coal feed rate control command based on the superheat after the steam-driven feedwater pump malfunctions.

[0036] In other words, the control system of the thermal power generating unit in this application embodiment can promptly identify whether the steam feedwater pump has malfunctioned, and when the steam feedwater pump malfunctions, it will trip the coal mill, start plasma for auxiliary combustion, and adjust the coal feed rate according to the superheat to ensure the safe and stable operation of the unit under abnormal operating conditions.

[0037] Figure 2 This is a structural block diagram of a fault diagnosis unit according to an embodiment of this application. Figure 2 As shown, Figure 1 The fault diagnosis unit 101 may include: a deviation determination subunit for unit load control command 201, a switch signal input module 202 for tripping steam-driven feedwater pump, a fault diagnosis subunit 203 for insufficient output of steam-driven feedwater pump, a fault output module 204 for steam-driven feedwater pump, a first OR module 205, and a first high limit module 206.

[0038] The subunit 203 for diagnosing insufficient output of the steam-driven feedwater pump is used to determine whether the steam-driven feedwater pump is experiencing insufficient output based on the main feedwater flow rate, the valve position value of the low-pressure valve, the valve position control command of the low-pressure valve, and the current month. The subunit 201 for determining the deviation of the unit load control command is used to output the corresponding deviation of the unit load control command based on the unit load command. For example... Figure 2 As shown, the insufficient output fault diagnosis subunit 203 of the steam-driven feedwater pump and the switch signal input module 202 for the tripping of the steam-driven feedwater pump are both connected to the input terminal of the first OR module 205. The output terminal of the first OR module 205 is connected to the input terminal of the deviation determination subunit 201 of the unit load control command; the output terminal of the deviation determination subunit 201 of the unit load control command is connected to the input terminal of the first high limit module 206; the output terminal of the first high limit module 206 is connected to the steam-driven feedwater pump fault output module 204.

[0039] In some embodiments of this application, the switch signal input module 202 for tripping the steam-driven feedwater pump outputs a high-level signal when the steam-driven feedwater pump trips, and a low-level signal when the steam-driven feedwater pump is operating normally. The steam-driven feedwater pump insufficient output fault diagnosis subunit 203 outputs a high-level signal when the steam-driven feedwater pump experiences an insufficient output fault, and outputs a low-level signal when the steam-driven feedwater pump does not experience an insufficient output fault. When the first OR module 205 outputs a high level, the unit load control command deviation determination subunit 201 outputs the corresponding unit load command deviation value according to the unit load command. The first high limit module 206 is set with a first deviation threshold. If the unit load command deviation value is greater than the first deviation threshold, the first high limit module 206 outputs a high-level signal, i.e., the steam-driven feedwater pump fault output module 204 outputs a signal indicating a fault in the steam-driven feedwater pump.

[0040] In other words, if the load command deviation of the unit exceeds the first deviation threshold when the steam-driven feedwater pump trips or experiences insufficient output, it is determined that the steam-driven feedwater pump has malfunctioned.

[0041] In some embodiments of this application, such as Figure 2 As shown, the deviation determination subunit 201 for unit load control commands includes: an analog signal input module 201-1 for unit load control commands, a first switching module 201-2, a first constant module 201-3, and a first subtraction module 201-4. The output of the first OR module 205 is connected to the S terminal of the first switching module 201-2; the analog signal input module 201-1 for unit load control commands is connected to the PV2 terminal of the first switching module 201-2; the first constant module 201-3 is connected to the PV1 terminal of the first switching module 201-2; the output of the first switching module 201-2 and the analog signal input module 201-1 for unit load control commands are both connected to the input of the first subtraction module 201-4; and the output of the first subtraction module 201-4 is connected to the first high limit module 206.

[0042] In other words, if the steam-driven feedwater pump trips or its output is insufficient, the S terminal of the first switching module 201-2 will be a high-level signal, and the PV1 terminal will be triggered. That is, the output of the first switching module 201-2 will be the set value in the first constant module 201-3. The first subtraction module 201-4 will output the unit load deviation value according to the unit load control command and the corresponding set value. If the unit load deviation value is greater than the first deviation threshold in the first high limit module 206, it will be determined that the steam-driven feedwater pump has malfunctioned.

[0043] In some other embodiments of this application, the fault diagnosis unit may further include a first low-limit module 207 and a steam-driven feedwater pump fault reset module 208. The output terminal of the first subtraction module 201-4 is connected to the input terminal of the first low-limit module 207, and the output terminal of the first low-limit module 207 is connected to the steam-driven feedwater pump fault reset module 208. That is, if the unit load deviation value is less than the second deviation threshold set in the first low-limit module 207, a steam-driven feedwater pump fault reset is determined.

[0044] As one possible implementation, the steam-driven feedwater pump insufficient output fault diagnosis subunit 203 can be used to determine the target feedwater flow fitting equation corresponding to the current month from multiple preset feedwater flow fitting equations, and determine the feedwater flow setpoint corresponding to the low-pressure valve position value based on the low-pressure valve position value and the target feedwater flow fitting equation; determine the valve position command deviation value based on the main feedwater flow value and the feedwater flow setpoint value; compare the low-pressure valve position value with the preset valve position threshold, and compare the valve position command deviation value with the preset deviation threshold; if the low-pressure valve position value is greater than the valve position threshold and the valve position command deviation value is greater than the deviation threshold, then it is determined that the feedwater pump has insufficient output fault.

[0045] Next, with Figure 3 As an example, the structure of the subunit for diagnosing insufficient output of a steam-driven feedwater pump is illustrated. For example... Figure 3 As shown, Figure 2 The subunit 203 for diagnosing insufficient output of the steam-driven feedwater pump may include: an analog signal input module 301 for the low-pressure valve position; a switch signal input module 302 for the manual / automatic switching control command of the low-pressure valve; an analog signal input module 303 for the feedwater flow fitting equation under winter conditions; an analog signal input module 304 for the feedwater flow fitting equation under summer conditions; an analog signal input module 305 for the winter / summer condition model switching control command; an analog signal input module 306 for the main feedwater flow; an analog signal input module 307 for the low-pressure valve regulation control command; a first switching module 308; a second switching module 309; and a first subtraction module 300. 10. First constant module 311, First high limit module 312, Second constant module 313, First low limit module 314, Third constant module 315, Third switching module 316, Second high limit module 317, Fourth constant module 318, First multiplication module 319, First pulse module 320, First addition module 321, Second low limit module 322, Fifth constant module 323, Third high limit module 324, Sixth constant module 325, First amplitude limiting module 326, Second pulse module 327, First AND module 328, First RS trigger module 329, Low-pressure valve regulation control command output 330, Fault diagnosis output for insufficient output of steam-driven feedwater pump 331.

[0046] Specifically, the analog signal input module 303 for the feedwater flow fitting equation under winter conditions is connected to the "PV1" terminal of the second switching module 309; the analog signal input module 304 for the feedwater flow fitting equation under summer conditions is connected to the "PV2" terminal of the second switching module 309; the analog signal input module 305 for the winter and summer condition model switching control command is connected to the "S" terminal of the second switching module 309; and the output terminal of the second switching module 309 and the analog signal input terminal for the main feedwater flow are also connected. Module 306 is connected to the input terminal of the first subtraction module 310; the output terminal of the first subtraction module 310 and the second constant module 313 are both connected to the input terminal of the first high limit module 312; the output terminal of the first subtraction module 310 and the third constant module 315 are both connected to the input terminal of the first low limit module 314; the output terminals of the first constant module 311, the first high limit module 312, and the first low limit module 314 are all connected to the input terminal of the first multiplication module 319; the third switching module 316 The output terminal of the first multiplication module 319 is connected to the "PV1" terminal of the third switching module 316; the analog signal input module 307 for the low-pressure valve regulation control command is connected to the "PV2" terminal of the third switching module 316; the switch signal input module 302 for the low-pressure valve manual and automatic switching control command is connected to the "S" terminal of the third switching module 316; the output terminals of the first multiplication module 319 and the third switching module 316 are connected to the input terminals of the first addition module 321, and the output terminal of the first addition module 321 is connected to the input terminal of the first limiting module 326; the output terminal of the first limiting module 326 is connected to the "PV1" terminal of the first switching module 308; the analog signal input module 301 for the low-pressure valve position is connected to the "PV2" terminal of the first switching module 308; the switch signal input module 202 for the low-pressure valve manual and automatic switching control command is connected to the "S" terminal of the first switching module 308, and the output terminal of the first switching module 308 is connected to the low-pressure valve regulation control command output terminal 330.

[0047] In other words, the second switching module 309 outputs the water supply flow setpoint corresponding to the valve position of the low-pressure valve based on the winter and summer control commands. The first subtraction module 310 outputs the deviation value between the water supply flow setpoint and the main water supply flow value. The first multiplication module 319 calculates the corresponding valve position command deviation value. The first addition module 321 adds the current valve position control command to the valve position command deviation value to obtain the valve position control command at the next moment.

[0048] like Figure 3As shown, the output of the first multiplication module 319 and the fifth constant module 323 are both connected to the input of the second low limit module 322, and the output of the second low limit module 322 is connected to the input of the second pulse module 327; the output of the first multiplication module 319 and the sixth constant module 325 are both connected to the input of the third high limit module 324; the analog signal input module 301 for the low-pressure valve position and the fourth constant module 318 are both connected to the input of the second high limit module 317, and the second high limit module 317... The output terminal is connected to the input terminal of the first pulse module 320; the output terminals of the third high limit module 324 and the first pulse module 320 are both connected to the input terminal of the first AND module 328; the output terminal of the second pulse module 327 is connected to the "R" terminal of the first RS trigger module 329, the output terminal of the first AND module 328 is connected to the "S" terminal of the first RS trigger module 329, and the "DV" terminal of the first RS trigger module 329 is connected to the fault diagnosis output terminal 331 of the steam-driven feedwater pump.

[0049] In other words, if the valve position value is higher than the constant value set in the fourth constant module 318, the second high limit module 317 outputs a high level. At the same time, if the valve position command deviation value output by the first multiplication module 319 is greater than the set value in the sixth constant module 325, the third high limit module 324 outputs a high level, thereby causing the first AND module 328 to output a high level, and the second low limit module 322 to output a low level, causing the "DV" terminal of the first RS trigger module 329 to output a high level, that is, the steam pump has a power shortage fault.

[0050] Figure 4 This is a structural block diagram of a first control unit according to an embodiment of this application. Figure 4 As shown, Figure 1 The first control unit 102 may include: a switch signal input module 401 indicating that the steam-driven feedwater pump has failed, a switch signal input module 402 indicating that the steam-driven feedwater pump fault monitoring function has been activated, a switch signal input module 403 indicating that the steam-driven feedwater pump fault has been reset, a first AND module 404, a first NOT module 405, a second OR module 406, a first RS trigger module 407, and a control module 408 that continuously trips the coal mill and starts the plasma system.

[0051] Specifically, the switch signal input module 401 for the faulty steam-driven feedwater pump and the switch signal input module 402 for the activated steam-driven feedwater pump fault monitoring function are both connected to the input terminal of the first AND module 404; the switch signal input module 402 for the activated steam-driven feedwater pump fault monitoring function is connected to the input terminal of the first NOT module 405; the output terminals of the switch signal input module 401 for the reset steam-driven feedwater pump fault and the first NOT module 405 are both connected to the input terminal of the second OR module 406; the output terminal of the first AND module 404 is connected to the S terminal of the first RS trigger module 407; the output terminal of the second OR module 406 is connected to the R terminal of the first RS trigger module 407; and the DV terminal of the first RS trigger module 407 is connected to the control module 408 for the continuous tripping coal mill and the start of the plasma system.

[0052] In some embodiments of this application, if the steam-driven feedwater pump has failed, the switch signal input module 401 indicating a failed steam-driven feedwater pump outputs a high-level signal; if the steam-driven feedwater pump has not failed, the switch signal input module 401 indicating a failed steam-driven feedwater pump outputs a low-level signal. If the result of the insufficient output fault diagnosis subunit of the fault diagnosis unit in the fault diagnosis unit is used, the switch signal input module 402 indicating the activation of the steam-driven feedwater pump fault monitoring function outputs a high-level signal; otherwise, it outputs a low-level signal.

[0053] In other words, if the steam-driven feedwater pump has failed and the fault monitoring function is activated, and the fault in the steam-driven feedwater pump has not been reset, the first RS trigger module 407 outputs a high-level signal, which triggers the control module 408 to trip the coal mills and start the plasma system. Once triggered, the control module 408 trips the coal mills in a preset sequence, keeping two coal mills running, and simultaneously starts the plasma system for auxiliary combustion.

[0054] Figure 5 This is a structural block diagram of a second control unit according to an embodiment of this application. Figure 5 As shown, Figure 1 The second control unit 103 may include: a superheat correction subunit 501, a switch signal input module 502 for when the steam-driven feedwater pump has failed, a second constant module 503, a second switching module 504, a second inertia module 505, and a coal feed rate control command output module 506 for when the steam-driven feedwater pump fails.

[0055] Among them, the switch signal input module 506 for the faulty steam-driven feedwater pump is connected to the S terminal of the second switching module 504, the superheat correction subunit 501 is connected to the PV1 terminal of the second switching module 504, and the second constant module 503 is connected to the PV2 terminal of the second switching module 504; the output terminal of the second switching module 504 is connected to the input terminal of the second inertia module 505, and the output terminal of the second inertia module 505 is connected to the coal feed rate control command output module 506 when the steam-driven feedwater pump fails.

[0056] In some embodiments of this application, the superheat correction subunit 501 is used to output the coal feed rate based on changes in superheat. When the steam-driven feedwater pump fails, the S terminal of the second switching module 504 is a high-level signal. At this time, the second switching module 504 triggers the PV1 terminal, that is, the second switching module 504 outputs the coal feed rate. After conversion by the second inertial module 505, the coal feed rate control command when the steam-driven feedwater pump fails is obtained.

[0057] As one possible implementation, such as Figure 5 As shown, the superheat correction subunit 501 may include: an analog signal input module 501-1 for superheat, a first function module 501-2, a first inertial module 501-3, a second subtraction module 501-4, and a first addition module 501-5. Specifically, the analog signal input module 501-1 for superheat is connected to the input terminals of both the first function module 501-2 and the first inertial module 501-3; the output terminals of both the first function module 501-2 and the first inertial module 501-3 are connected to the input terminal of the second subtraction module 501-4; the output terminals of both the first function module 501-2 and the second subtraction module 501-4 are connected to the input terminal of the first addition module 501-5; and the output terminal of the first addition module 501-5 is connected to the PV1 terminal of the second switching module.

[0058] The first function module 501-2 is used to convert superheat into coal feed rate, the second subtraction module 501-4 outputs the coal feed rate deviation value, and the first addition module 501-5 adds the converted coal feed rate to the deviation value and outputs the coal feed rate determined based on superheat.

[0059] According to the control system of the thermal power generating unit of this application, a fault diagnosis unit determines whether the steam-driven feedwater pump is malfunctioning based on the unit load control command, the main feedwater flow rate of the steam-driven feedwater pump, the valve position value of the low-pressure valve, the valve position control command of the low-pressure valve, and the current month. Upon malfunction of the steam-driven feedwater pump, the first and second control units are connected to trip the coal mill and start the plasma system, while simultaneously adjusting the coal feed rate according to the superheat. This solution not only promptly identifies faults in the pneumatic feedwater pump but also ensures the safe and stable operation of the unit when the steam-driven feedwater pump fails.

[0060] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0061] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0062] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A control system for a thermal power generating unit, characterized in that, The thermal power generating unit is equipped with a steam-driven feedwater pump and an electric feedwater pump; the system includes: The fault diagnosis unit is used to determine whether the steam-driven feedwater pump is malfunctioning based on the unit load control command, the main feedwater flow value of the steam-driven feedwater pump, the valve position value of the low-pressure valve, the valve position control command of the low-pressure valve, and the current month. The first control unit is used to trip the coal mill and start the plasma system after the steam-driven feedwater pump fails. The second control unit is used to determine the coal feed rate control command based on the superheat after the steam-driven feedwater pump fails.

2. The system according to claim 1, characterized in that, The fault diagnosis unit includes: a subunit for determining the deviation of the unit load control command, a switch signal input module for the tripping of the steam-driven feedwater pump, a fault diagnosis subunit for insufficient output of the steam-driven feedwater pump, a fault output module for the steam-driven feedwater pump, a first OR module, and a first high limit module; wherein: The steam-driven feedwater pump insufficient output fault diagnosis subunit is used to determine whether the steam-driven feedwater pump has an insufficient output fault based on the main feedwater flow rate value, the valve position value of the low-pressure valve, the valve position control command of the low-pressure valve, and the current month; both the steam-driven feedwater pump insufficient output fault diagnosis subunit and the switch signal input module for the steam-driven feedwater pump trip are connected to the input terminal of the first or second module; The deviation determination subunit for the unit load control command is used to output the corresponding deviation value of the unit load control command according to the unit load command; the output terminal of the first OR module is connected to the input terminal of the deviation determination subunit for the unit load control command; the output terminal of the deviation determination subunit for the unit load control command is connected to the input terminal of the first high limit module; the output terminal of the first high limit module is connected to the steam-driven feedwater pump fault output module.

3. The system according to claim 2, characterized in that, The deviation determination subunit for the unit load control command includes: an analog signal input module for the unit load control command, a first switching module, a first constant module, and a first subtraction module; wherein: The output terminal of the first OR module is connected to the S terminal of the first switching module; the analog signal input module for the unit load control command is connected to the PV2 terminal of the first switching module; the first constant module is connected to the PV1 terminal of the first switching module; the output terminal of the first switching module and the analog signal input module for the unit load control command are both connected to the input terminal of the first subtraction module; the output terminal of the first subtraction module is connected to the first high limit module.

4. The system according to claim 3, characterized in that, The fault diagnosis unit further includes a first low-limit module and a steam-driven feedwater pump fault reset module; wherein: The output of the first subtraction module is connected to the input of the first lower limit module; the output of the first lower limit module is connected to the steam-driven feedwater pump fault reset module.

5. The system according to claim 1, characterized in that, The first control unit includes: a switch signal input module indicating a fault in the steam-driven feedwater pump, a switch signal input module indicating that the fault monitoring function of the steam-driven feedwater pump is activated, a switch signal input module indicating that the fault in the steam-driven feedwater pump has been reset, a first AND module, a first NOT module, a second OR module, a first RS trigger module, and a control module that trips the coal mill and starts the plasma system; wherein: The switch signal input module for the faulty steam-driven feedwater pump and the switch signal input module for the activated steam-driven feedwater pump fault monitoring function are both connected to the input terminal of the first AND module; the switch signal input module for the activated steam-driven feedwater pump fault monitoring function is connected to the input terminal of the first NOT module; the output terminals of the switch signal input module for the reset faulty steam-driven feedwater pump and the first NOT module are both connected to the input terminal of the second OR module; the output terminal of the first AND module is connected to the S terminal of the first RS trigger module; the output terminal of the second OR module is connected to the R terminal of the first RS trigger module; the DV terminal of the first RS trigger module is connected to the control module for the coupled coal mill and the activated plasma system.

6. The system according to claim 1, characterized in that, The second control unit includes a superheat correction subunit, a switch signal input module for a faulty steam-driven feedwater pump, a second constant module, a second switching module, a second inertia module, and a coal feed rate control command output module for a faulty steam-driven feedwater pump; wherein: The switch signal input module for the faulty steam-driven feedwater pump is connected to the S terminal of the second switching module; the superheat correction subunit is connected to the PV1 terminal of the second switching module; the second constant module is connected to the PV2 terminal of the second switching module; the output terminal of the second switching module is connected to the input terminal of the second inertial module; and the output terminal of the second inertial module is connected to the coal feed rate control command output module when the steam-driven feedwater pump fails.

7. The system according to claim 6, characterized in that, The superheat correction subunit includes: an analog signal input module for superheat, a first function module, a first inertia module, a second subtraction module, and a first addition module; wherein: The analog signal input module for superheat is connected to the input terminal of the first function module and the input terminal of the first inertial module, respectively; the output terminal of the first function module and the output terminal of the first inertial module are both connected to the input terminal of the second subtraction module; the output terminal of the first function module and the output terminal of the second subtraction module are both connected to the input terminal of the first addition module; the output terminal of the first addition module is connected to the PV1 terminal of the second switching module.

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