A water-side booster pump system for an induced draft fan condenser and a control method under multivariable conditions

Abstract

A water-side booster pump system for an induced draft fan condenser and a control method under multiple variables, including heat exchange of two processes on the steam side and water side of the induced draft fan condenser, wherein the water side is equipped with two permanent magnet regulating booster pumps and one high-speed variable frequency booster pump, and a real-time flow meter is installed at the water-side inlet of the induced draft fan condenser, and the current of each booster pump can be monitored remotely; the condensate on the steam side of the induced draft fan condenser returns to the main engine condenser. The present invention can effectively realize the full-automatic tracking control of the booster pump, automatically determine the summer and winter working conditions, and adaptively start the corresponding booster pump; at the same time, the control target is determined by using the existing monitoring parameters, and the control target value is corrected in real time considering the unit load to determine the optimal control target value; the method takes into account the operation mode under accident conditions, and quickly and automatically tracks the target value according to the control requirements of non-disturbance response; if the control target value is exceeded and the water-side monitoring parameter exceeds the judgment value, an audible and visual alarm is output to promptly remind the operator to conduct a comprehensive inspection of the system.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal power generation equipped with an induced draft fan steam turbine, and in particular to an induced draft fan condenser water side booster pump system and a multivariable control method. Background Art

[0002] Steam-driven induced draft fans, a common feature of newly built power plant units, play a significant role in reducing plant power consumption and energy conservation. Small induced draft fans are typically installed in the boiler room, relatively far from the turbine room. Therefore, these small induced draft fans are typically equipped with independent condensers. Similar to the main engine condenser, the condenser also has steam and water side circuits. The water side circuit typically draws circulating water from the main engine, exchanging heat with the steam side within the condenser. Exhaust steam from the steam side small unit is cooled and condensed by the circulating water and then pumped back to the main engine condenser using an independent small unit condensate pump.

[0003] After the main engine's circulating water passes through the condenser of the induced draft fan, its flow rate slows, its pressure head decreases, and its heat exchange efficiency deteriorates. Under high unit load, the exhaust temperature of the induced draft fan gradually rises, and the condenser vacuum deteriorates. Therefore, a booster pump is typically installed on the water side of the condenser. Common booster pumps include high-speed variable-frequency pumps, fixed-speed pumps, and permanent-magnet pumps. Manual adjustments are often made during unit operation. Only after monitoring for deterioration in the condenser vacuum or rising exhaust temperature will a backup pump be activated or its speed adjusted to increase pump output.

[0004] For units equipped with high-speed variable-frequency pumps or permanent-magnet pumps, for example, the standard control setup typically involves the variable frequency drive or permanent-magnet speed governor automatically tracking the pump outlet pressure, or more optimally, the condenser water outlet temperature. However, this automatic adjustment approach suffers from three limitations: First, the circulating water system's flow rate is high, and simply adjusting the booster pumps will only minimally affect the pump outlet pressure. Even if all pumps are fully operational, the outlet pressure changes little, thus defeating the purpose of automatic pressure adjustment. Second, the main engine's circulating water temperature fluctuates significantly with ambient temperature, with significant differences between summer and winter operating conditions. When automatically tracking the condenser outlet temperature, in winter, the pumps barely need to be started to meet demand, while in summer, multiple booster pumps must be activated to achieve the desired effect. This approach also defeats the purpose of energy conservation and automatic tracking. Third, neither automatic adjustment approach considers the impact of load changes (and the corresponding induced draft fan speed) on the set target value. Since the unit operates under variable operating conditions and power, the load value (and the corresponding induced draft fan speed) should be a key variable in real-time correction of the control target value. Summary of the Invention

[0005] In order to solve the above-mentioned adverse effects and meet the requirements of energy conservation and consumption reduction, the present invention proposes a water-side booster pump system for an induced draft fan condenser and a control method under multiple variables, which can effectively realize fully automatic tracking control of the booster pump, automatically determine summer operating conditions and winter operating conditions, and adaptively start the corresponding booster pump; at the same time, the control target is determined by using existing monitoring parameters, and the control target is further corrected in real time considering the unit load.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] A water-side booster pump system for an induced draft fan condenser includes two circuits: a steam-side circuit and a water-side circuit.

[0008] The branch of the water-side circulation from the main engine circulating water main pipe passes through the flow meter 1 and the inlet electric valve 2 in sequence and enters the induced draft fan condenser F, and exchanges heat with the exhaust steam of the induced draft fan small unit D inside the induced draft fan condenser F. The induced draft fan small unit D is provided at the upper end of the induced draft fan condenser F. The heat exchange outlet section of the induced draft fan condenser F is connected to the booster pump inlet main pipe through the outlet electric valve 3, and the booster pump outlet is connected to the main engine circulating water main pipe;

[0009] The steam side circulation loop includes an induced draft fan small unit D. The exhaust end of the induced draft fan small unit D is connected to the induced draft fan condenser F, which performs surface heat exchange with the circulating water from the water side. The exhaust steam is condensed after cooling. The bottom of the induced draft fan condenser F is connected to the main engine condenser through the induced draft fan condensing device to complete the entire steam side circulation.

[0010] The output end of the booster pump inlet main pipe is divided into three paths, the first path is connected in sequence to the outlet electric valve 2 4, the booster pump 1A, the outlet check valve 1 7 and the outlet electric valve 5 10;

[0011] The second line is connected in sequence to the outlet electric valve 3 5, the booster pump 2 B, the outlet check valve 2 8 and the outlet electric valve 6 11;

[0012] The third line is connected in sequence to the outlet electric valve four 6, the booster pump three C, the outlet check valve three 9 and the outlet electric valve seven 12.

[0013] The booster pump 1 A and the booster pump 2 B are permanent magnet regulating pumps, and the booster pump 3 C is a high-speed variable frequency pump.

[0014] The induced draft fan condensation device has two parallel paths, the first path is provided with an induced draft fan condensate pump 1G and a pump outlet check valve 13; the second path is provided with an induced draft fan condensate pump 2H and a pump outlet check valve 214.

[0015] The induced draft fan small unit D is connected to the induced draft fan E.

[0016] The inlet of the induced draft fan condenser F is provided with measuring points for measuring the circulating water temperature t1 and pressure P1, as well as the outlet temperature t2 and pressure P2 measuring points. The booster pump outlet main pipe is provided with a measuring point P3 for measuring the outlet main pipe pressure.

[0017] A multivariable control method for a water-side booster pump system of an induced draft fan condenser comprises the following steps:

[0018] Take the configuration of three booster pump units as an example, two of which are permanent magnet regulating pumps and one is a high-speed variable frequency pump;

[0019] a. Based on the ambient temperature T0, winter mode and summer mode are distinguished, where the ambient temperature below 15°C is defined as winter mode, and the ambient temperature greater than or equal to 15°C is defined as summer mode;

[0020] b. Under winter operating conditions, one permanent magnet regulating pump is started and the other is kept in standby mode. The high-speed variable frequency regulating pump is used as an emergency standby pump. Under summer operating conditions, the number of booster pumps in operation is configured according to the load size.

[0021] c. Load-dependent adjustment of the number of booster pumps in operation is limited to summer operating conditions. When the load is below 60% Pe (rated load), one permanent magnet pump is in operation, the other is on standby, and the high-speed variable frequency pump serves as an emergency backup pump. When the load is greater than or equal to 60% Pe (rated load), both permanent magnet pumps are automatically started, and the high-speed variable frequency pump serves as the backup pump.

[0022] d. Set the temperature rise Δt (Δt = t2 - t1) at the inlet and outlet of the water side of the induced draft fan condenser F as the target value for automatic control, and set the target value to three levels: less than 5°C, 5°C to 10°C, and greater than 10°C;

[0023] The initial value of the permanent magnet pump adjustment ratio (0-100%) is set to 25%. If the temperature rise is within 5°C, the current minimum opening is maintained. Once the temperature rise exceeds 5°C, the opening of the permanent magnet adjustment device is automatically increased until the opening of the permanent magnet adjustment device reaches 100% full opening. The goal is to control the temperature rise within 10°C. When the temperature rise exceeds 10°C, an audible and visual alarm is issued to remind the operator to monitor the water side parameters.

[0024] e. Set water side parameter monitoring alarm, including the induced draft fan condenser F inlet water temperature t1, return water temperature t2, inlet water pressure P1, return water pressure P2, condenser water side flow Q, booster pump operating current I A / I B / I C, booster pump outlet pressure P3 and valve switch status; when the booster pump is running, once the flow rate drops (drops by more than 30% from the current flow rate) and the booster pump operating current drops (drops by more than 10% from the current current), it is first determined that the filter of the running booster pump is clogged, and it is necessary to start the backup high-speed frequency conversion adjustment pump, stop the current booster pump, take isolation measures, and prepare to clean the filter;

[0025] Once the valve switch status changes (the switch status disappears or reverses), the inlet and return water temperature changes rapidly by more than 5°C, or the inlet and outlet water pressure drops by 10% of the current pressure, an audible and visual alarm signal will be output to remind the operator to check whether there is any abnormality in the system;

[0026] f. Use the unit load point to make real-time corrections to the temperature rise target value. When the load is lower than 60% Pe, the speed of the induced draft fan small unit D is maintained at a constant speed of 4000 r / min. When the load is in the operating range of 60% Pe to 100% Pe, the speed of the induced draft fan small unit D gradually increases with the load. The load and the corresponding speed are used as independent variables, and the control target value Δt is used as the dependent variable. Through PID adjustment (multiplying the PID deviation gain by a coefficient of 0.5), the three form a corresponding broken line function, and ultimately output the optimal control target value.

[0027] The specific control method of the system is as follows:

[0028] 1) Before starting the unit, water is injected into the system. First, open the inlet electric valve 2 and outlet electric valve 1 3 of the induced draft fan condenser F, as well as the inlet and outlet electric valves 2 4, 3, 4, 5, 6, 5, 6, and 7 of booster pump 1A, booster pump 2B, and booster pump 3C. Introduce the main engine circulating water system into the induced draft fan condenser F, and inject water into the system pipelines to check for leaks. During this process, focus on monitoring the inlet pressure P1 and outlet pressure P2 of the induced draft fan condenser F and the outlet main pipe pressure P3 of the booster pump. When the monitored pressures P1, P2, and P3 are the same, the system pipeline water injection is determined to be complete.

[0029] 2) After water injection is completed, prepare to start the booster pump; close the outlet electric valve 510, electric valve 11, and electric valve 12 of the three booster pumps, and keep the other valves in the state during water injection, that is, the valves are fully open. Remotely start the booster pump A at the operator station, and after starting, interlock and open the outlet electric valve 510, and monitor the operating current I A Within the rated current range, the initial instruction of the permanent magnet adjustment device is set to 25%. After the booster pump A operates normally, the permanent magnet adjustment device is automatically put into operation. At the same time, the booster pump B is put into standby mode, and the booster pump C is put into emergency standby mode.

[0030] 3) Automatically activate the operating mode according to the ambient temperature T0 monitoring value, that is, when T0 is less than 15℃, it is automatically judged as winter mode, and when T0 is greater than or equal to 15℃, it is automatically judged as summer mode. In winter mode, the start permission of booster pump 2B is automatically blocked, and only booster pump 1A is allowed to start. In summer mode, the start permission of booster pump 2B is automatically released, and the number of booster pumps in operation is automatically triggered according to the real-time load value P of the unit;

[0031] 4) When the unit load is lower than 60% Pe (rated load), one booster pump A is kept in automatic operation, and the permanent magnet adjustment device is used to automatically increase the speed to meet the control target value Δt (i.e., the inlet and outlet temperature rise of the induced draft fan condenser F). Within this load range, Δt is required to be less than or equal to 5°C. The operator can make fine adjustments within a range of 5°C based on the actual temperature rise. If booster pump A trips during operation, booster pump B will be overridden (unconditionally started), and the control target value Δt of booster pump B will be automatically set to the value before booster pump A tripped;

[0032] 5) When the unit load reaches 60% Pe (rated load), the rotor blades of the induced draft fan E gradually fully open, and the speed of the induced draft fan small unit D needs to be increased. Correspondingly, the exhaust steam volume of the induced draft fan small unit D increases, and the exhaust steam temperature rises. At this time, booster pump 2 B automatically starts to maintain the boosting operation of both units. The permanent magnet adjustment instruction of booster pump 2 B is automatically loaded into the current value of booster pump 1 A, and synchronously tracks the control target value Δt set for booster pump 1 A;

[0033] 6) When the load value is in the range of 60%Pe to 100%Pe, the permanent magnet adjustment device instructs the speed to correct the control target Δt, so that Δt is within 10°C and at an optimal value. Once booster pump 1A or booster pump 2B trips during this operation, the emergency standby booster pump 3C is started in an interlocking manner, and the target control value Δt of booster pump 3C is automatically tracked to the value of booster pump 1A or booster pump 2B before tripping. If the actual inlet and return water temperature rise Δt exceeds 10°C during the adjustment process, an audible and visual alarm signal is output to remind the operator to check for any abnormalities in the system.

[0034] 7) During the whole operation of the unit, the water side parameters are fully monitored, including the inlet water temperature t1, return water temperature t2, inlet water pressure P1, return water pressure P2, water side flow rate Q of the condenser F of the induced draft fan, and the operating current of the booster pump (I A / I B / I C), booster pump outlet pressure P3 and valve switch status; when the booster pump is running, once the inlet flow of the induced draft fan condenser F drops rapidly (drops by more than 30% from the current flow), and the operating current of the booster pump drops rapidly (drops by more than 10% of the current current), it is judged that the filter of the running booster pump is blocked, and it is necessary to start the emergency standby booster pump three C, shut down the current booster pump, take isolation measures, and prepare to clean the filter. Once the valve switch status changes (the switch status disappears or reverses), the inlet and return water temperature changes by more than 5°C, and the inlet and outlet water pressure drops by 10% of the current pressure, an audible and visual alarm signal will be output to remind the operating personnel to check the system abnormality.

[0035] Beneficial effects of the present invention:

[0036] 1) The three booster pumps can realize automatic control of the whole process and full load section.

[0037] 2) Added the judgment of summer and winter working conditions, and adaptively started the number of booster pumps.

[0038] 3) The inlet and outlet water temperature rise Δt of the induced draft fan condenser is clearly defined as the automatic control target of the booster pump, and a three-level control range of Δt is set, namely less than 5°C, 5-10°C and greater than 10°C.

[0039] 4) Introducing the unit load (corresponding to the induced draft fan speed) to modify the control target value Δt, ensuring that the control target value is the optimal value within the control range. When the load is below 60%Pe, the induced draft fan speed is maintained at a constant speed of 4000 r / min. When the load is between 60%Pe and 100%Pe, the induced draft fan speed is gradually increased with the load. The load and the corresponding speed are used as independent variables, and the control target value is used as the dependent variable. Through PID adjustment (multiplying the PID deviation gain by a coefficient of 0.5), the three form a corresponding broken line function, ultimately outputting the optimal control target value.

[0040] 5) The entire control method takes into account the operation mode of abnormal accident conditions. That is, when the operating pump trips due to an accident, the standby pump automatically starts and automatically tracks the control target to the set value of the operating pump before the trip.

[0041] 6) The water side parameters are monitored more comprehensively, and the existing parameters are used to determine filter blockage and system abnormalities and output sound and light alarms. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0043] The present invention will be described in further detail below with reference to the accompanying drawings.

[0044] like Figure 1As shown, take the configuration of three booster pump units as an example, two of which are permanent magnet regulating pumps and one is a high-speed variable frequency pump;

[0045] a. Based on the ambient temperature T0, winter mode and summer mode are distinguished, where the ambient temperature below 15°C is defined as winter mode, and the ambient temperature greater than or equal to 15°C is defined as summer mode;

[0046] b. Under winter operating conditions, one permanent magnet regulating pump is started and the other is kept in standby mode. The high-speed variable frequency regulating pump is used as an emergency standby pump. Under summer operating conditions, the number of booster pumps in operation is configured according to the load size.

[0047] c. Load-dependent adjustment of the number of booster pumps in operation is limited to summer operating conditions. When the load is below 60% Pe (rated load), one permanent magnet pump is in operation, the other is on standby, and the high-speed variable frequency pump serves as an emergency backup pump. When the load is greater than or equal to 60% Pe (rated load), both permanent magnet pumps are automatically started, and the high-speed variable frequency pump serves as the backup pump.

[0048] d. Set the temperature rise Δt (Δt = t2 - t1) at the inlet and outlet of the water side of the induced draft fan condenser F as the target value for automatic control, and set the target value to three levels: less than 5°C, 5°C to 10°C, and greater than 10°C;

[0049] The initial value of the permanent magnet pump adjustment ratio (0-100%) is set to 25%. If the temperature rise is within 5°C, the current minimum opening is maintained. Once the temperature rise exceeds 5°C, the opening of the permanent magnet adjustment device is automatically increased until the opening of the permanent magnet adjustment device reaches 100% full opening. The goal is to control the temperature rise within 10°C. When the temperature rise exceeds 10°C, an audible and visual alarm is issued to remind the operator to monitor the water side parameters.

[0050] e. Set water side parameter monitoring alarm, including the induced draft fan condenser F inlet water temperature t1, return water temperature t2, inlet water pressure P1, return water pressure P2, condenser water side flow Q, booster pump operating current I A / I B / I C , booster pump outlet pressure P3 and valve switch status; when the booster pump is running, once the flow rate drops (drops by more than 30% from the current flow rate) and the booster pump operating current drops (drops by more than 10% from the current current), it is first determined that the filter of the running booster pump is clogged, and it is necessary to start the backup high-speed frequency conversion adjustment pump, stop the current booster pump, take isolation measures, and prepare to clean the filter;

[0051] Once the valve switch status changes (the switch status disappears or reverses), the inlet and return water temperature changes rapidly by more than 5°C, or the inlet and outlet water pressure drops by 10% of the current pressure, an audible and visual alarm signal will be output to remind the operator to check whether there is any abnormality in the system;

[0052] f. Use the unit load point to make real-time corrections to the temperature rise target value. When the load is lower than 60% Pe, the speed of the induced draft fan small unit D is maintained at a constant speed of 4000 r / min. When the load is in the operating range of 60% Pe to 100% Pe, the speed of the induced draft fan small unit D gradually increases with the load. The load and the corresponding speed are used as independent variables, and the control target value Δt is used as the dependent variable. Through PID adjustment (multiplying the PID deviation gain by a coefficient of 0.5), the three form a corresponding broken line function, and ultimately output the optimal control target value.

[0053] The three booster pumps (A / B / C) can achieve current I A / I B / I C Remote real-time monitoring.

[0054] The circulating water inlet flow rate Q can also be remotely transmitted and monitored in real time.

[0055] The present invention can effectively realize fully automatic tracking and control of the booster pump, automatically determine summer operating conditions and winter operating conditions, and adaptively start the corresponding booster pump; at the same time, it uses existing monitoring parameters to determine the control target, takes into account the unit load to make real-time corrections to the control target value, and determines the optimal control target value; this method takes into account the operating mode under accident conditions, and quickly and automatically tracks the target value in accordance with the control requirements of non-disturbance response; if the control target value is exceeded and the water-side monitoring parameter exceeds the judgment value, an audible and visual alarm is output to promptly remind the operator to conduct a comprehensive inspection of the system.

[0056] The specific control method of the system is as follows:

[0057] 1) Before starting the unit, water is injected into the system. First, open the inlet electric valve 2 and outlet electric valve 1 3 of the induced draft fan condenser F, as well as the inlet and outlet electric valves 2 4, 3, 4, 5, 6, 5, 6, and 7 of booster pump 1A, booster pump 2B, and booster pump 3C. Introduce the main engine circulating water system into the induced draft fan condenser F, and inject water into the system pipelines to check for leaks. During this process, focus on monitoring the inlet pressure P1 and outlet pressure P2 of the induced draft fan condenser F and the outlet main pipe pressure P3 of the booster pump. When the monitored pressures P1, P2, and P3 are the same, the system pipeline water injection is determined to be complete.

[0058] 2) After water injection is completed, prepare to start the booster pump; close the outlet electric valve 510, electric valve 11, and electric valve 12 of the three booster pumps, and keep the other valves in the state during water injection, that is, the valves are fully open. Remotely start the booster pump A at the operator station, and after starting, interlock and open the outlet electric valve 510, and monitor the operating current I AWithin the rated current range, the initial instruction of the permanent magnet adjustment device is set to 25%. After the booster pump A operates normally, the permanent magnet adjustment device is automatically put into operation. At the same time, the booster pump B is put into standby mode, and the booster pump C is put into emergency standby mode.

[0059] 3) Automatically activate the operating mode according to the ambient temperature T0 monitoring value, that is, when T0 is less than 15℃, it is automatically judged as winter mode, and when T0 is greater than or equal to 15℃, it is automatically judged as summer mode. In winter mode, the start permission of booster pump 2B is automatically blocked, and only booster pump 1A is allowed to start. In summer mode, the start permission of booster pump 2B is automatically released, and the number of booster pumps in operation is automatically triggered according to the real-time load value P of the unit;

[0060] 4) When the unit load is lower than 60% Pe (rated load), one booster pump A is kept in automatic operation, and the permanent magnet adjustment device is used to automatically increase the speed to meet the control target value Δt (i.e., the inlet and outlet temperature rise of the induced draft fan condenser F). Within this load range, Δt is required to be less than or equal to 5°C. The operator can make fine adjustments within a range of 5°C based on the actual temperature rise. If booster pump A trips during operation, booster pump B will be overridden (unconditionally started), and the control target value Δt of booster pump B will be automatically set to the value before booster pump A tripped;

[0061] 5) When the unit load reaches 60% Pe (rated load), the rotor blades of the induced draft fan E gradually fully open, and the speed of the induced draft fan small unit D needs to be increased. Correspondingly, the exhaust steam volume of the induced draft fan small unit D increases, and the exhaust steam temperature rises. At this time, booster pump 2 B automatically starts to maintain the boosting operation of both units. The permanent magnet adjustment instruction of booster pump 2 B is automatically loaded into the current value of booster pump 1 A, and synchronously tracks the control target value Δt set for booster pump 1 A;

[0062] 6) When the load value is in the range of 60%Pe to 100%Pe, the permanent magnet adjustment device instructs the speed to correct the control target Δt, so that Δt is within 10°C and at an optimal value. Once booster pump 1A or booster pump 2B trips during this operation, the emergency standby booster pump 3C is started in an interlocking manner, and the target control value Δt of booster pump 3C is automatically tracked to the value of booster pump 1A or booster pump 2B before tripping. If the actual inlet and return water temperature rise Δt exceeds 10°C during the adjustment process, an audible and visual alarm signal is output to remind the operator to check for any abnormalities in the system.

[0063] 7) During the whole operation of the unit, the water side parameters are fully monitored, including the inlet water temperature t1, return water temperature t2, inlet water pressure P1, return water pressure P2, water side flow rate Q of the condenser F of the induced draft fan, and the operating current of the booster pump (I A / I B / I C), booster pump outlet pressure P3 and valve switch status; when the booster pump is running, once the inlet flow of the induced draft fan condenser F drops rapidly (drops by more than 30% from the current flow), and the operating current of the booster pump drops rapidly (drops by more than 10% of the current current), it is judged that the filter of the running booster pump is blocked, and it is necessary to start the emergency standby booster pump three C, shut down the current booster pump, take isolation measures, and prepare to clean the filter. Once the valve switch status changes (the switch status disappears or reverses), the inlet and return water temperature changes by more than 5°C, and the inlet and outlet water pressure drops by 10% of the current pressure, an audible and visual alarm signal will be output to remind the operating personnel to check the system abnormality.

Claims

1. A multivariable control method for a water-side booster pump system of an induced draft fan condenser, characterized in that: The water-side booster pump system of the induced draft fan condenser includes two-way circulation on the steam side and the water side; The branch of the water side circulation from the main engine circulating water main pipe enters the induced draft fan condenser (F) through the flow meter (1) and the inlet electric valve (2) in turn, and exchanges heat with the exhaust steam of the induced draft fan small unit (D) inside the induced draft fan condenser (F). The induced draft fan small unit (D) is arranged at the upper end of the induced draft fan condenser (F). The heat exchange outlet section of the induced draft fan condenser (F) is connected to the booster pump inlet main pipe through the outlet electric valve 1 (3), and the booster pump outlet is connected to the main engine circulating water main pipe; The steam side circulation loop includes an induced draft fan (D), the exhaust end of the induced draft fan (D) is connected to the induced draft fan condenser (F), and performs surface heat exchange with the circulating water from the water side. The exhaust steam is condensed after cooling. The bottom of the induced draft fan condenser (F) is connected to the main engine condenser through the induced draft fan condensing device to complete the entire steam side circulation; A control method for a water-side booster pump system of an induced draft fan condenser under multivariable conditions comprises the following steps: a. Based on the ambient temperature T0, winter mode and summer mode are distinguished, where the ambient temperature below 15°C is defined as winter mode, and the ambient temperature greater than or equal to 15°C is defined as summer mode; b. In winter, one permanent magnet regulating pump is started and the other permanent magnet regulating pump is kept as standby. The high-speed variable frequency regulating pump is used as an emergency standby pump. In summer, the number of booster pumps is configured according to the load size. c. The load adjustment of the number of booster pumps in operation is limited to summer conditions. When the rated load Pe is below 60%, one permanent magnet adjustment pump is in operation, and the other permanent magnet adjustment pump is on standby. The high-speed variable frequency adjustment pump is used as an emergency standby pump. When the rated load Pe is greater than or equal to 60%, the two permanent magnet adjustment pumps are automatically started, and the high-speed variable frequency adjustment pump is used as a standby pump. d. The temperature rise Δt of the inlet and outlet of the water side of the induced draft fan condenser (F) is used as the target value of automatic control, and the target value is set to three levels, namely less than 5℃, 5℃~10℃ and greater than 10℃; The initial value of the permanent magnet pump adjustment ratio is set to 25%. If the temperature rise is within 5°C, the current minimum opening is maintained. Once the temperature rise exceeds 5°C, the opening of the permanent magnet adjustment device is automatically increased until the opening of the permanent magnet adjustment device is 100% fully open. The goal is to control the temperature rise within 10°C. When the temperature rise exceeds 10°C, an audible and visual alarm is issued to remind the operator to monitor the water side parameters. e. Set up water side parameter monitoring and alarm. Water side parameters include induced draft fan condenser (F) inlet water temperature t1, return water temperature t2, inlet water pressure P1, return water pressure P2, condenser water side flow Q, booster pump operating current I A / I B / I C , booster pump outlet pressure P3 and valve switch status; When the booster pump is running, if the flow rate drops and the operating current of the booster pump drops, it is first determined that the filter of the running booster pump is blocked. It is necessary to start the standby high-speed frequency conversion adjustment pump, stop the current booster pump, take isolation measures, and prepare to clean the filter; Once the valve switch status changes, the inlet and return water temperature changes rapidly by more than 5°C, or the inlet and outlet water pressure drops by 10% of the current pressure, an audible and visual alarm signal will be output to remind the operator to check whether there is any abnormality in the system; f. Use the unit load point to make real-time corrections to the temperature rise target value. When the load is lower than 60% of the rated load Pe, the speed of the induced draft fan (D) is kept at a constant speed of 4000r / min. When the load is in the operating range of 60% of the rated load Pe~100% of the rated load Pe, the speed of the induced draft fan (D) is gradually increased with the load. The load and the corresponding speed are used as independent variables, and the control target value Δt is used as the dependent variable. Through PID adjustment, the three form a corresponding broken line function, and finally output the optimal control target value; The output end of the booster pump inlet main pipe is divided into three paths, the first path is connected in sequence to the outlet electric valve 2 (4), the booster pump 1 (A), the outlet check valve 1 (7) and the outlet electric valve 5 (10); The second path is connected in sequence to the outlet electric valve three (5), the booster pump two (B), the outlet check valve two (8) and the outlet electric valve six (11); The third path is connected in sequence to the outlet electric valve four (6), the booster pump three (C), the outlet check valve three (9) and the outlet electric valve seven (12); The booster pump 1 (A) and booster pump 2 (B) are permanent magnet regulating pumps, and booster pump 3 (C) is a high-speed variable frequency pump; The induced draft fan condensation device is provided with two paths in parallel, the first path is provided with an induced draft fan condensate pump 1 (G) and a pump outlet check valve 1 (13); the second path is provided with an induced draft fan condensate pump 2 (H) and a pump outlet check valve 2 (14); The induced draft fan (D) is connected to the induced draft fan (E); The inlet of the induced draft fan condenser (F) is provided with measuring points for measuring the circulating water temperature t1 and pressure P1, as well as outlet temperature t2 and pressure P2 measuring points. The outlet main pipe of the booster pump is provided with a measuring point P3 for measuring the outlet main pipe pressure.

2. The control method of a multivariable booster pump system on the water side of an induced draft fan condenser according to claim 1 is characterized in that: The specific control method of the system is: 1) Before starting the unit, water is injected into the system. First, open the inlet electric valve (2) and outlet electric valve 1 (3) of the induced draft fan condenser (F), as well as the inlet and outlet electric valves 2 (4), outlet electric valve 3 (5), outlet electric valve 4 (6), outlet electric valve 5 (10), outlet electric valve 6 (11), and outlet electric valve 7 (12) of booster pump 1 (A), booster pump 2 (B), and booster pump 3 (C), and introduce the main engine circulating water system into the induced draft fan condenser (F). Water is injected into the system pipeline to check for leaks. During this process, the inlet pressure P1 and outlet pressure P2 of the induced draft fan condenser (F) and the outlet main pipe pressure P3 of the booster pump are monitored. When the monitored three-point pressures P1, P2, and P3 are the same, it is determined that the system pipeline water injection is completed; 2) After water injection is completed, prepare to start the booster pump; close the outlet electric valves 5 (10), 6 (11), and 7 (12) of the three booster pumps, and keep the other valves in the state of water injection, that is, the valves are fully open. Start the booster pump 1 (A) remotely at the operator station, and after starting, interlock and open the outlet electric valve 5 (10), and monitor the operating current I A Within the rated current range, the initial command of the permanent magnet adjustment device is set to 25%. After the booster pump 1 (A) operates normally, the permanent magnet adjustment device is automatically put into operation. At the same time, the booster pump 2 (B) is put into standby mode, and the booster pump 3 (C) is put into emergency standby mode. 3) Automatically activate the operation mode according to the monitoring value of the ambient temperature T0, that is, when T0 is less than 15℃, it is automatically judged as winter mode, and when T0 is greater than or 15℃, it is automatically judged as summer mode. In winter mode, the start permission of booster pump 2 (B) is automatically blocked, and only booster pump 1 (A) is allowed to start. In summer mode, the start permission of booster pump 2 (B) is automatically released, and the number of running booster pumps is automatically triggered according to the real-time load value P of the unit; 4) When the unit load is lower than 60% of the rated load Pe, keep one booster pump (A) running automatically, and use the permanent magnet adjustment device to automatically load the speed to meet the control target value Δt. In this load range, Δt is required to be less than or equal to 5°C. The operator makes fine adjustments within the range of 5°C according to the actual temperature rise. Once booster pump (A) trips during operation, booster pump (B) is overrun and started, and the control target value Δt of booster pump (B) is automatically set to the value before booster pump (A) trips; 5) When the unit load reaches 60% of the rated load Pe, the moving blades of the induced draft fan (E) are gradually fully opened, and the speed of the induced draft fan (D) needs to be increased. The exhaust volume of the corresponding induced draft fan (D) increases, and the exhaust temperature rises. At this time, the booster pump 2 (B) automatically starts to keep the two boosters running. The permanent magnet adjustment command of the booster pump 2 (B) is automatically loaded to the current value of the booster pump 1 (A), and synchronously tracks the control target value Δt set by the booster pump 1 (A); 6) When the load value is in the range of 60% rated load Pe to 100% rated load Pe, the permanent magnet adjustment device instructs the correction of the control target Δt by the receiving speed, so that Δt is within 10°C and is at an optimal value. Once the booster pump 1 (A) or booster pump 2 (B) trips during the operation, the emergency standby booster pump 3 (C) is started in an interlocked manner, and the target control value Δt of the booster pump 3 (C) is automatically tracked to the value of the booster pump 1 (A) or booster pump 2 (B) before the trip; when the actual inlet and return water temperature rise Δt is greater than 10°C during the adjustment process, an audible and visual alarm signal is output to remind the operator to check the system for abnormalities; 7) During the whole operation of the unit, the water side parameters are fully monitored, including the condenser (F) water inlet temperature t1, return water temperature t2, water inlet pressure P1, return water pressure P2, condenser (F) water side flow Q, booster pump operating current I A / I B / I C , booster pump outlet pressure P3 and valve switch status; When the booster pump is running, if the inlet flow of the condenser (F) of the induced draft fan drops rapidly and the operating current of the booster pump drops rapidly, it is judged that the filter of the running booster pump is blocked and it is necessary to start the emergency standby booster pump 3 (C), shut down the current booster pump, take isolation measures and prepare to clean the filter. Once the valve switch status changes, the inlet and return water temperature changes by more than 5°C, and the inlet and outlet water pressure drops by 10% of the current pressure, an audible and visual alarm signal will be output to remind the operating personnel to check the system abnormality.

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