A steam-electric dual-drive system for induced draft fans and a control method thereof

Abstract

The present application provides a steam-electric dual-drive system for an induced draft fan and a control method thereof, the system comprising: an induced draft fan; an asynchronous motor, coaxially connected to the induced draft fan and connected to the plant power system through a high-voltage switch; a small steam turbine and a small steam turbine steam inlet regulating valve; a clutchable constant-speed ratio gearbox, coaxially connected to the asynchronous motor and the small steam turbine; a clutch engagement switch, arranged on the clutchable constant-speed ratio gearbox; a control system, connected to the asynchronous motor and the small steam turbine steam inlet regulating valve to control the opening and closing of the asynchronous motor, and adjust the opening of the small steam turbine steam inlet regulating valve according to the current operating stage and the pre-obtained target opening model. The method is used to control the above system. Stable switching between the two driving modes of small steam turbine drive and electric motor drive is achieved, and rapid response can be made when a system failure occurs, ensuring the stable operation of the induced draft fan steam-electric dual-drive system under various operating conditions, and improving the stability and reliability of the induced draft fan steam-electric dual-drive system.

Description

Technical Field

[0001] The present application relates to the field of electronic power technology, and in particular to a steam-electric dual-drive system for an induced draft fan and a control method thereof. Background Art

[0002] Traditional induced draft fans are directly driven by electric motors, which consume a lot of electricity. Energy-saving and consumption-reducing transformation of auxiliary equipment in thermal power plants is an inevitable requirement for coal-fired power units to achieve high-quality transformation and development in the new era. As an operating mode that has emerged in recent years, the steam-electric dual-drive system of induced draft fans can greatly improve the economic benefits of power plants.

[0003] However, when using the steam-electric dual-drive induced draft fan steam turbine solution, the switching between the two drive modes is relatively complicated. If the switching is not done properly, it may cause a safety accident. And when the asynchronous motor suddenly stops operating, if the output of the small steam turbine is not adjusted in time, the induced draft fan will be overloaded or underloaded, which will cause the furnace negative pressure to exceed the limit, thus causing the unit to trip. Summary of the invention

[0004] In view of the problems in the prior art, the present application provides a steam-electric dual-drive system for an induced draft fan and a control method thereof, which can at least partially solve the problems in the prior art.

[0005] In a first aspect, the present application provides a steam-electric dual-drive system for an induced draft fan, comprising:

[0006] induced draft fan;

[0007] An asynchronous motor, coaxially connected to the induced draft fan and connected to the plant power system via a high-voltage switch;

[0008] A small steam engine and a small steam engine steam inlet regulating valve connected to the small steam engine;

[0009] A clutchable fixed speed ratio gearbox is arranged between the asynchronous motor and the small steam engine and is coaxially connected to the asynchronous motor and the small steam engine;

[0010] A clutch engagement switch, arranged on the clutchable fixed speed ratio gearbox;

[0011] A control system is connected to the asynchronous motor and the small steam turbine steam inlet regulating valve to control the opening and closing of the asynchronous motor and adjust the opening of the small steam turbine steam inlet regulating valve according to the current operation stage and a pre-obtained target opening model.

[0012] The control modes of the control system include: valve position control mode and speed control mode; the control system includes:

[0013] A judging unit, used to judge whether the running condition of the asynchronous motor meets the preset locomotive side starting condition;

[0014] A control unit, when the operating condition meets the preset maintenance side start condition, is used to obtain the current operating condition data of the system, start the valve position control mode, and adjust the opening of the small steam turbine steam inlet regulating valve according to the operating condition data and the pre-obtained target opening model;

[0015] The mode switching unit is used to switch the valve position control mode to the speed control mode so that the small steam engine keeps running at the meshing speed.

[0016] Wherein, the control system further comprises: a closing unit, which is used to close the steam inlet regulating valve of the small steam turbine when the operating condition does not meet the preset locomotive side start condition.

[0017] Among them, it also includes:

[0018] A power detection device is connected to the asynchronous motor.

[0019] The induced draft fan is a constant speed device, and the load is adjusted by changing the blade angle on the hub.

[0020] In a second aspect, the present application provides a control method for an induced draft fan steam-electric dual-drive system, comprising:

[0021] Receive control instructions;

[0022] Determine the operation stage of the steam-electric dual-drive system of the induced draft fan according to the control instruction; the operation stage includes a startup stage, a shutdown stage and an accident stage;

[0023] If the operation stage is an accident stage, the opening of the small steam turbine steam inlet regulating valve is adjusted according to a pre-obtained target opening model.

[0024] Wherein, adjusting the opening of the small steam turbine steam inlet regulating valve according to the pre-obtained target opening model includes:

[0025] Detecting the operating status of the asynchronous motor and determining whether the operating status meets the preset maintenance side start condition;

[0026] If the operating condition meets the preset maintenance side start condition, the valve position control mode is adopted to obtain the current operating condition data of the system, and the opening of the small steam turbine steam inlet regulating valve is adjusted according to the operating condition data and the pre-obtained target opening model;

[0027] Switch to the speed control mode to keep the small steam engine running at the meshing speed.

[0028] Wherein, adjusting the opening of the small steam turbine steam inlet regulating valve according to the operating condition data and the pre-obtained target opening model includes:

[0029] At least one of a small steam turbine steam inlet pressure, a small steam turbine steam inlet temperature, a small steam turbine steam inlet flow rate, a small steam turbine back pressure, a small steam turbine exhaust temperature, a small steam turbine speed, a unit load, and an asynchronous motor power is obtained as operating condition data;

[0030] Inputting the operating condition data into the target opening model to obtain the target opening of the small steam turbine steam inlet regulating valve;

[0031] The opening of the small steam turbine steam inlet regulating valve is adjusted to the target opening.

[0032] Among them, it also includes:

[0033] If the operating conditions do not meet the preset maintenance side start conditions, close the small steam turbine steam inlet regulating valve.

[0034] If the operation phase is a startup phase, the method further includes:

[0035] Turning on the asynchronous motor and opening the steam inlet regulating valve of the small steam engine to start the small steam engine;

[0036] Use the speed control mode to adjust the opening of the steam inlet valve of the small steam turbine so that the small steam turbine can warm up at the preset warm-up speed for the first preset time;

[0037] Increasing the speed of the small steam engine to the rated speed, so that the small steam engine maintains the rated speed for a second preset time;

[0038] Increasing the speed of the small steam engine to a first preset speed, so that the clutch engagement switch triggers an engagement signal, and the clutchable fixed speed ratio gearbox engages;

[0039] Switch to the valve position control mode and increase the opening of the small steam turbine steam inlet regulating valve until the output power of the asynchronous motor is positive.

[0040] Wherein, if the operation phase is a shutdown phase, it also includes:

[0041] Use valve position control mode to gradually reduce the opening of the small turbine steam inlet regulating valve until the output power of the asynchronous motor is negative;

[0042] Slowly and continuously reducing the opening of the small steam turbine steam inlet regulating valve until the output power of the asynchronous motor is within a preset range;

[0043] Rapidly and continuously reducing the opening of the steam inlet regulating valve of the small steam engine until the speed of the small steam engine is less than the second preset speed, so that the clutch engagement switch stops sending the engagement signal, and the clutchable fixed speed ratio gearbox stops engaging;

[0044] Closing the steam inlet regulating valve of the small steam turbine to shut down the small steam turbine;

[0045] The asynchronous motor is switched off.

[0046] Among them, it also includes:

[0047] Collecting historical opening data and corresponding operating condition data of the steam inlet regulating valve of the small steam turbine;

[0048] Normalizing the working condition data and dividing them into a training set and a validation set;

[0049] The training set and the validation set are used to train the preset target opening model.

[0050] The induced draft fan steam-electric dual-drive system and control method provided in the present application receive control instructions; determine the operating stage of the induced draft fan steam-electric dual-drive system according to the control instructions; the operating stage includes a startup stage, a shutdown stage and an accident stage; if the operating stage is the accident stage, adjust the opening of the small steam turbine steam inlet regulating valve according to a pre-obtained target opening model, thereby achieving stable switching between the two driving modes of small steam turbine drive and electric motor drive, and being able to respond quickly when a system failure occurs, and adjust the operation of the small steam turbine according to the failure situation combined with the target opening model control, thereby ensuring the stable operation of the induced draft fan steam-electric dual-drive system in multiple operating states such as startup, operation, stop and accident, and improving the stability and reliability of the induced draft fan steam-electric dual-drive system. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0052] Figure 1 This is a schematic diagram of the structure of a steam-electric dual-drive system for an induced draft fan provided in one embodiment of the present application;

[0053] Figure 2 It is a schematic diagram of the control system structure provided by an embodiment of the present application;

[0054] Figure 3 It is a schematic diagram of the control system structure provided by an embodiment of the present application;

[0055] Figure 4 is a flow chart of a method for controlling a steam-electric dual-drive system of an induced draft fan provided in an embodiment of the present application;

[0056] Figure 5 This is a flow chart of a control method for an induced draft fan steam-electric dual-drive system in an accident phase provided by an embodiment of the present application;

[0057] Figure 6is a flow chart of a method for controlling a steam-electric dual-drive system of an induced draft fan provided in an embodiment of the present application;

[0058] Figure 7 is a flow chart of a method for controlling a steam-electric dual-drive system of an induced draft fan provided in an embodiment of the present application;

[0059] Figure 8 This is a flow chart of a control method for an induced draft fan steam-electric dual-drive system in a startup phase provided by an embodiment of the present application;

[0060] Fig. 9 It is a flow chart of a control method for an induced draft fan steam-electric dual-drive system in a closing stage provided by an embodiment of the present application;

[0061] Fig.10 It is an image of the functional relationship between the induced draft fan power and the unit load provided in one embodiment of the present application. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below in conjunction with the accompanying drawings. Here, the illustrative embodiments of the present invention and their descriptions are used to explain the present invention, but are not intended to limit the present invention. It should be noted that, in the absence of conflict, the embodiments in this application and the features in the embodiments can be combined with each other arbitrarily.

[0063] Figure 1 Schematic diagram of the structure of the steam-electric dual-drive system of the induced draft fan provided in one embodiment of the present application. Figure 1 As shown, the induced draft fan steam-electric dual drive system provided in the present application includes: an induced draft fan 110, an asynchronous motor 120, a high-voltage switch 130, a small steam turbine 140, a small steam turbine steam inlet regulating valve 150, a clutchable constant speed ratio gearbox 160, a clutch engagement switch 170, and a control system 180;

[0064] The asynchronous motor 120 is coaxially connected to the induced draft fan 110 and is connected to the auxiliary power system 200 via a high-voltage switch 130;

[0065] Specifically, the asynchronous motor 120 is used to drive the induced draft fan 110 to work. Since the asynchronous motor 120 is coaxially connected to the induced draft fan 110, the asynchronous motor 120 and the induced draft fan 110 have the same rotation speed. When the high-voltage switch 130 is closed, the asynchronous motor 120 is connected to the auxiliary power system 200. When the output power is positive, the asynchronous motor 120 is in the generator working mode, and the excess electric energy is transmitted to the auxiliary power system 200; when the output power is negative, the asynchronous motor 120 is in the motor working mode, and absorbs electric energy from the auxiliary power system 200.

[0066] In one embodiment, a power detection device 190 may be provided and connected to the asynchronous motor 120 to detect the output power of the asynchronous motor 120 and to detect the state of the asynchronous motor 120 .

[0067] In one embodiment, the induced draft fan 110 is a constant speed device, and load adjustment is performed by changing the angle of blades on the hub.

[0068] The small steam turbine 140 is connected to a small steam turbine steam inlet regulating valve 150 ; the power and speed of the small steam turbine 140 can be controlled by controlling the opening of the small steam turbine steam inlet regulating valve 150 .

[0069] The clutchable constant speed ratio gearbox 160 is disposed between the asynchronous motor 120 and the small steam engine 140, and is coaxially connected with the asynchronous motor 120 and the small steam engine 140; the clutch engagement switch 170 is disposed on the clutchable constant speed ratio gearbox 160;

[0070] Specifically, when the speed ratio of the small steam engine 140 and the asynchronous motor 120 reaches the preset speed ratio of the clutchable fixed speed ratio gearbox 160, the clutch engagement switch 170 triggers the engagement signal, the clutchable fixed speed ratio gearbox 160 engages, the small steam engine 140 is connected to the asynchronous motor 120, and starts to supply energy to the asynchronous motor 120, driving the asynchronous motor 120 to operate. The preset speed ratio can be set according to the actual working conditions, for example, the speed ratio is preset to 7:1, but the present application is not limited thereto.

[0071] In one embodiment, the speed of the induced draft fan 110 and the asynchronous motor 120 is a certain value. At this time, when the small steam turbine 140 reaches the meshing speed, the clutchable fixed speed ratio gearbox 160 is meshed. The speed of the induced draft fan 110 can be, for example, 745 rpm, and the meshing speed is 5215 rpm. The meshing speed can be adjusted according to the speed of the asynchronous motor 120 and the preset speed ratio of the clutchable fixed speed ratio gearbox 160.

[0072] The control system 180 is connected to the asynchronous motor 120 and the small steam turbine steam inlet regulating valve 150 to control the opening and closing of the asynchronous motor 120 and adjust the opening of the small steam turbine steam inlet regulating valve 150 according to the current operation stage and the pre-obtained target opening model.

[0073] Specifically, the control system 180 can control the asynchronous motor 120 and the small steam turbine steam inlet regulating valve 150. When controlling the small steam turbine steam inlet regulating valve 150, it includes a valve position control mode and a speed control mode. In the valve position control mode, the control system 180 can adjust the small steam turbine steam inlet regulating valve 150 to a specific valve position; in the speed control mode, the control system 180 adjusts the opening of the small steam turbine steam inlet regulating valve 150 to make the small steam turbine 140 reach a specific speed. The operation stage can include a startup stage, an operation stage, a shutdown stage, and an accident stage.

[0074] In one embodiment, the current operation stage is an accident stage, such as Figure 2 As shown, the control system 180 includes: a judgment unit 181 , a control unit 182 and a mode switching unit 183 .

[0075] The judging unit 181 is used to judge whether the running status of the asynchronous motor 120 satisfies the preset locomotive side starting condition;

[0076] Specifically, the maintenance side start condition includes at least one of the following conditions:

[0077] a. The temperature of the bearing bush on the small turbine side of the asynchronous motor is less than 60℃;

[0078] b. The temperature of the bearing on the induced draft fan side of the asynchronous motor is less than 60°C;

[0079] c. The lubricating oil pressure of the asynchronous motor is greater than 0.08MPa;

[0080] d. The first output of the asynchronous motor tripping is "large vibration of the bearing on the small turbine side of the asynchronous motor";

[0081] e. The first output of the asynchronous motor tripping is "large vibration of the asynchronous motor induced draft fan side bearing".

[0082] The relevant data in the above conditions can be directly obtained from the system operation detection data, and other side start conditions can be added as needed. If the operation status of the asynchronous motor 120 meets the preset maintenance side start conditions, it means that the accident at this time is a fault caused by the disconnection of the high-voltage switch 130 due to electrical factors, and the asynchronous motor 120 has no defects and can maintain operation in the power-off state.

[0083] When the operating status meets the preset maintenance side start condition, the control unit 182 is used to obtain the current operating data of the system, start the valve position control mode, and adjust the opening of the small steam turbine steam inlet regulating valve 150 according to the operating data and the pre-obtained target opening model;

[0084] Specifically, when the operation status of the asynchronous motor 120 meets the preset maintenance side start-up conditions, the small steam turbine 140 can still drive the induced draft fan 110 to work through the asynchronous motor 120, but because the high-voltage switch 130 is disconnected at this time, the asynchronous motor 120 is not connected to the plant power system 200, so the asynchronous motor 120 cannot obtain power from the plant power system 200, nor can it transmit excess power to the plant power system 200. At this time, the output power of the small steam turbine 140 should be controlled to match the load value of the induced draft fan 110. If the output of the small steam turbine 140 is too large, the induced draft fan 110 will be in an overloaded state. If the output of the small steam turbine 140 is too small, the induced draft fan 110 will be in an underloaded state, and there is a risk of causing the furnace negative pressure to exceed the limit and thus cause the unit to trip.

[0085] By inputting the operating condition data into the pre-obtained target opening model, the opening of the small steam turbine steam inlet regulating valve 150 when the output power of the small steam turbine 140 matches the load value of the induced draft fan 110 can be obtained, and the control unit 182 adjusts the small steam turbine steam inlet regulating valve 150 to the corresponding opening in the valve position control mode to ensure stable operation of the system. The operating condition data may include the small steam turbine steam inlet pressure, the small steam turbine steam inlet temperature, the small steam turbine steam inlet flow, the small steam turbine back pressure, the small steam turbine exhaust temperature, the small machine speed, the unit load, the asynchronous motor power, etc. The operating condition data can be adjusted according to the actual situation, and the specific content of the operating condition data is not limited in this application. The target opening model can be obtained by training based on the historical operating condition data and the historical opening of the small steam turbine steam inlet regulating valve 150.

[0086] The mode switching unit 183 is used to switch the valve position control mode to the speed control mode, so that the small steam engine keeps running at the meshing speed.

[0087] Specifically, when the system is in a stable operating state, the mode switching unit 183 switches the control system 180 to the speed control mode, so that the small steam turbine 140 maintains operation at the meshing speed, ensuring that the clutchable constant speed ratio gearbox 160 is always in a meshing state while stably driving the induced draft fan 110 to operate.

[0088] exist Figure 2 Based on the embodiment, further, Figure 3 As shown, the control system 180 also includes:

[0089] The closing unit 184 is used to close the small steam turbine steam inlet regulating valve 150 when the operating condition does not meet the preset locomotive side start condition.

[0090] Specifically, when the operating condition of the asynchronous motor 120 does not meet the preset maintenance-side start-up conditions, it means that the asynchronous motor 120 itself fails and cannot continue to drive the induced draft fan 110 to operate. At this time, the closing unit 184 closes the small steam turbine steam inlet regulating valve 150 to stop the small steam turbine 140 from operating.

[0091] The induced draft fan steam-electric dual-drive system provided by the present application is provided with an induced draft fan; an asynchronous motor, which is coaxially connected to the induced draft fan and connected to the plant power system through a high-voltage switch; a small steam turbine and a small steam turbine steam inlet regulating valve connected to the small steam turbine; a clutchable constant-speed ratio gearbox, which is arranged between the asynchronous motor and the small steam turbine and coaxially connected to the asynchronous motor and the small steam turbine; a clutch engagement switch, which is arranged on the clutchable constant-speed ratio gearbox; a control system, which is connected to the small steam turbine steam inlet regulating valve to adjust the opening of the small steam turbine steam inlet regulating valve according to the current operating stage and the pre-obtained target opening model, thereby realizing stable switching between the two driving modes of small steam turbine drive and electric motor drive, and being able to respond quickly when a system fault occurs, and adjusting the operation of the small steam turbine according to the fault condition combined with the target opening model control to prevent the unit from tripping, thereby ensuring the stable operation of the induced draft fan steam-electric dual-drive system in various operating states such as start-up, operation, stop, and accident, and improving the stability and reliability of the induced draft fan steam-electric dual-drive system.

[0092] Based on the same inventive concept, the embodiment of the present application also provides a control method for an induced draft fan steam-electric dual drive system, which is implemented based on the device described in the above embodiment, as described in the following embodiment. Since the principle of solving the problem by the control method for an induced draft fan steam-electric dual drive system is similar to that of an induced draft fan steam-electric dual drive system, the repeated parts will not be repeated.

[0093] The following takes the control system as an example of the execution subject to illustrate the specific implementation process of the induced draft fan steam-electric dual-drive system control method provided by the embodiment of the present invention.

[0094] Figure 4 is a flow chart of a method for controlling a steam-electric dual-drive system of an induced draft fan provided in an embodiment of the present application. Figure 4 As shown, the control method of the steam-electric dual-drive system of the induced draft fan provided in the present application includes:

[0095] S401: receiving a control instruction;

[0096] S402: determining the operation stage of the steam-electric dual-drive system of the induced draft fan according to the control instruction; the operation stage includes the startup stage, the shutdown stage and the accident stage;

[0097] S403: If the operation stage is the accident stage, adjust the opening of the small steam turbine steam inlet regulating valve according to the pre-obtained target opening model.

[0098] The control method of the steam-electric dual-drive system of the induced draft fan provided in the present application receives a control instruction; determines the operating stage of the steam-electric dual-drive system of the induced draft fan according to the control instruction; the operating stage includes a startup stage, a shutdown stage and an accident stage; if the operating stage is the accident stage, adjusts the opening of the small steam turbine steam inlet regulating valve according to a pre-obtained target opening model, thereby realizing a stable switching between the two driving modes of small steam turbine drive and electric motor drive, and is able to respond quickly when a system failure occurs, and adjusts the operation of the small steam turbine according to the fault condition combined with the target opening model control to prevent the unit from tripping, thereby ensuring the stable operation of the steam-electric dual-drive system of the induced draft fan in a variety of operating states such as startup, operation, stop and accident, thereby improving the stability and reliability of the steam-electric dual-drive system of the induced draft fan.

[0099] Each step is explained in detail below.

[0100] S401: receiving a control instruction;

[0101] Specifically, the control instruction can be issued by the staff. For example, when the induced draft fan steam-electric dual-drive system is started, the staff types a start control instruction, or selects the start button to make the system generate a start instruction; the control instruction can also be automatically generated by the induced draft fan steam-electric dual-drive system by detecting the current working status. For example, a start control instruction is generated when the system is started. This application does not limit the source of the control instruction.

[0102] S402: determining the operation stage of the steam-electric dual-drive system of the induced draft fan according to the control instruction; the operation stage includes the startup stage, the shutdown stage and the accident stage;

[0103] Specifically, the control instruction may include the current operation stage information of the induced draft fan steam-electric dual drive system. The control system controls the opening of the small steam turbine steam inlet regulating valve according to the current operation stage, thereby controlling the output power of the small steam turbine.

[0104] S403: If the operation stage is the accident stage, adjust the opening of the small steam turbine steam inlet regulating valve according to the pre-obtained target opening model.

[0105] Specifically, when in the accident stage, the control system inputs the unit load and other operating condition data into the target opening model to obtain the target opening of the small steam turbine steam inlet regulating valve. The target opening refers to the opening value that matches the output power of the small machine with the induced draft fan load under the current operating conditions.

[0106] In one embodiment, if Figure 5 As shown, S403 includes:

[0107] S501: Detecting the operating status of the asynchronous motor and determining whether the operating status meets the preset locomotive side start condition;

[0108] Specifically, the maintenance side start condition includes at least one of the following conditions:

[0109] a. The temperature of the bearing bush on the small turbine side of the asynchronous motor is less than 60℃;

[0110] b. The temperature of the bearing on the induced draft fan side of the asynchronous motor is less than 60°C;

[0111] c. The lubricating oil pressure of the asynchronous motor is greater than 0.08MPa;

[0112] d. The first output of the asynchronous motor tripping is "large vibration of the bearing on the small turbine side of the asynchronous motor";

[0113] e. The first output of the asynchronous motor tripping is "large vibration of the asynchronous motor induced draft fan side bearing".

[0114] The relevant data in the above conditions can be directly obtained from the system operation detection data, and other side start conditions can be added as needed. If the operation status of the asynchronous motor meets the preset maintenance side start conditions, it means that the accident at this time is a fault caused by the disconnection of the high-voltage switch due to electrical factors, and the asynchronous motor has no defects and can maintain operation in the power-off state.

[0115] S502: If the operating status meets the preset maintenance side start condition, the valve position control mode is adopted to obtain the current operating data of the system, and the opening of the small steam turbine steam inlet regulating valve is adjusted according to the operating data and the pre-obtained target opening model;

[0116] Specifically, when the operating condition of the asynchronous motor meets the preset maintenance-side start-up conditions, the small steam turbine can still drive the induced draft fan to work through the asynchronous motor. However, since the asynchronous motor is disconnected from the plant power system, the output power of the small steam turbine cannot be adjusted. Therefore, it is necessary to use the target opening model to obtain the target opening of the small steam turbine steam inlet regulating valve to ensure that the output power of the small steam turbine matches the induced draft fan load.

[0117] In one embodiment, if Figure 6 As shown, S502 includes:

[0118] S601: obtaining at least one of a small steam turbine steam inlet pressure, a small steam turbine steam inlet temperature, a small steam turbine steam inlet flow rate, a small steam turbine back pressure, a small steam turbine exhaust temperature, a small steam turbine speed, a unit load, and an asynchronous motor power as operating condition data;

[0119] Specifically, the relationship between the opening of the small steam turbine steam inlet regulating valve and the small steam turbine output power is affected by factors such as the small steam turbine steam inlet pressure, the small steam turbine steam inlet temperature, the small steam turbine steam inlet flow, the small steam turbine back pressure, and the small steam turbine exhaust temperature; the induced draft fan load is affected by factors such as the unit load. Therefore, the target opening value that matches the small steam turbine output power with the induced draft fan load is closely related to the above physical quantities. The above data can be directly obtained from the system operation detection data. When the asynchronous motor is shut down, the asynchronous motor power is 0.

[0120] S602: Inputting the operating condition data into the target opening model to obtain the target opening of the small turbine steam inlet regulating valve;

[0121] Specifically, before inputting the operating condition data into the target opening model, it needs to be normalized. The control system inputs the normalized operating condition data into the target opening model, and the output result of the target opening model is the target opening of the small steam turbine steam inlet regulating valve.

[0122] S603: Adjust the opening of the small turbine steam inlet regulating valve to the target opening.

[0123] Specifically, the control system adjusts the opening of the small steam turbine steam inlet regulating valve to the target opening in the valve position control mode, thereby ensuring that the output power of the small steam turbine matches the induced draft fan load, thereby ensuring the stable operation of the power system.

[0124] The control method of the induced draft fan steam-electric dual-drive system provided in the present application obtains the target opening of the small steam turbine steam inlet regulating valve by acquiring the operating condition data and inputting the target opening model; the opening of the small steam turbine steam inlet regulating valve is adjusted to the target opening, thereby ensuring that the induced draft fan steam-electric dual-drive system can quickly adjust the operating state when the high-voltage switch is disconnected due to electrical factors, preventing the furnace negative pressure from exceeding the limit and causing the unit to trip, so that the induced draft fan steam-electric dual-drive system can still operate stably during the accident stage, thereby improving the stability of the power system.

[0125] In one embodiment, if Figure 7 As shown, the control method of the induced draft fan steam-electric dual drive system provided in the present application also includes:

[0126] S701: Collect historical opening data of the steam inlet regulating valve of the small steam turbine and corresponding operating condition data;

[0127] Specifically, the operating condition data may include the small steam turbine steam inlet pressure, small steam turbine steam inlet temperature, small steam turbine steam inlet flow, small steam turbine back pressure, small steam turbine exhaust temperature, small steam turbine speed, unit load, asynchronous motor power, etc. The correspondence between a set of operating condition data and the opening data is represented by a vector, for example, x1=(0.943, 353, 38.5, 10.5, 46.8, 5200, 900, 100), y1=80, and the physical quantities contained in the operating condition data can be adjusted according to actual conditions such as system settings.

[0128] S702: normalizing the operating condition data and dividing it into a training set and a validation set;

[0129] Specifically, since the numerical ranges of different physical quantities in the operating condition data vary greatly, the operating condition data needs to be normalized. For example, the maximum and minimum normalization method can be used to achieve normalization, which can be expressed by the following formula:

[0130]

[0131] In addition, logarithmic function normalization, L2 norm normalization, etc. can also be used, and this application does not limit the specific method of normalization. After normalization, the historical operating condition data and its corresponding historical opening data are divided into a training set and a verification set.

[0132] S703: Use the training set and the validation set to train a preset target opening model.

[0133] Specifically, the target opening model is a linear model, and the mean square error is used as the error function. The target opening model can be expressed by formula (2), and the mean square error function can be expressed by formula (3):

[0134] y(x)=θ0+θ1x1+…+θ n x n (2)

[0135]

[0136] Among them, J(θ) represents the function value of the mean square error function, θ represents the coefficient set of the target opening model, and θ i represents the i-th coefficient in the coefficient set, where 0≤i≤n, n represents the number of samples, and x i Represents a set of operating data vectors in a sample, y(x i ) represents the target opening model using the operating condition data vector x i The calculated target opening value, y i Indicates the historical opening value of this group of samples.

[0137] The partial derivative of the mean square error is calculated to update the parameters using the gradient descent method. The partial derivative function can be expressed by formula (4), and the update function can be expressed by formula (5).

[0138]

[0139]

[0140] Where η represents the learning rate. When J(θ) is less than a preset value, the training is stopped to obtain the final target opening model. The preset value can be, for example, 10 -6 This value can be set according to actual needs and this application does not impose any restrictions on this.

[0141] S503: Switch to the speed control mode to keep the small steam engine running at the meshing speed.

[0142] Specifically, when the system is in a stable operating state, the control system switches to the speed control mode to keep the small steam turbine running at the meshing speed, ensuring that the clutchable constant speed ratio gearbox is always in a meshing state while stably driving the induced draft fan to operate.

[0143] In one embodiment, after receiving the control instruction of the accident stage for a preset time, the control system considers that the system has entered a stable operation state and automatically switches to the speed control mode for control. The preset time is, for example, 5s and can be set according to actual conditions.

[0144] On the basis of the above embodiments, further, when in the accident stage, the control method of the induced draft fan steam-electric dual drive system provided by the present application further includes:

[0145] If the operating conditions do not meet the preset maintenance side start conditions, close the small steam turbine steam inlet regulating valve.

[0146] Specifically, when the operating condition of the asynchronous motor does not meet the preset maintenance-side start-up conditions, it means that the asynchronous motor itself has failed and can no longer drive the induced draft fan. At this time, the control system closes the small steam turbine steam inlet regulating valve to stop the small steam turbine.

[0147] The control method of the steam-electric dual-drive system of the induced draft fan provided in the present application determines whether the operating condition of the asynchronous motor meets the preset maintenance-side start-up conditions; if so, a valve position control mode is adopted to obtain the current operating condition data of the system, and adjust the opening of the small steam turbine steam inlet regulating valve according to the operating condition data and a pre-obtained target opening model; if not, the small steam turbine steam inlet regulating valve is closed, thereby realizing the control of the steam-electric dual-drive system of the induced draft fan in the event of an accident. In the event of an accident, the small steam turbine is not directly shut down, but different control methods are adopted according to the operating condition of the asynchronous motor, thereby reducing the failure rate of the steam-electric dual-drive system of the induced draft fan and further improving the stability of the system.

[0148] On the basis of the above embodiments, further, Figure 8 As shown, when in the startup stage, the control method of the induced draft fan steam-electric dual drive system provided by the present application also includes:

[0149] S801: Start the asynchronous motor and open the steam inlet regulating valve of the small steam engine to start the small steam engine;

[0150] Specifically, in the start-up stage, the high-voltage switch is closed, the asynchronous motor is connected to the plant power system, and the control system starts the asynchronous motor. At this time, the small steam turbine has not yet been started, and the induced draft fan is driven by the asynchronous motor. The plant power system supplies power to the asynchronous motor, and the output power of the asynchronous motor is negative. In one embodiment, after the high-voltage switch is closed, the asynchronous motor is automatically turned on. The high-voltage switch can be controlled by the control system or manually closed. After the asynchronous motor is turned on, the control system starts the small steam turbine.

[0151] S802: adopting the speed control mode, adjusting the opening of the steam inlet regulating valve of the small steam turbine, so that the small steam turbine warms up at the preset warm-up speed for the first preset time;

[0152] Specifically, the control system adopts a speed control mode, and the small steam engine can be warmed up at multiple different warm-up speeds to gradually increase the speed. For example, the first preset time is 70 minutes, and the warm-up speed includes a first warm-up speed of 800 rpm and a second warm-up speed of 2000 rpm. After the small steam engine runs at the first warm-up speed for 40 minutes, it is increased to the second warm-up speed and runs for 30 minutes to complete the warm-up. The warm-up time, the number of warm-up speeds, and the speed value can be set according to actual conditions, and this application does not limit this.

[0153] S803: increasing the speed of the small steam engine to the rated speed, so that the small steam engine maintains the rated speed for a second preset time;

[0154] Specifically, after the warm-up is completed, the small steam engine is increased to run at a rated speed. The rated speed of the small steam engine is, for example, 5200 rpm, and this value varies according to different small steam engine models and the like.

[0155] S804: increasing the speed of the small steam engine to a first preset speed, so that the clutch engagement switch triggers an engagement signal, and the clutch fixed speed ratio gearbox is engaged;

[0156] Specifically, the rated speed of the small steam turbine is less than the meshing speed of the clutch-type fixed-speed ratio gearbox. Therefore, the speed of the small steam turbine should continue to be increased to the first preset speed, so that the clutch engagement switch triggers the engagement signal, and the clutch-type fixed-speed ratio gearbox engages. At this time, the induced draft fan is driven by the small steam turbine and the asynchronous motor, and the factory power system still supplies power to the asynchronous motor, and the output power of the asynchronous motor is negative. The first preset speed should be slightly greater than the meshing speed to prevent the clutch-type fixed-speed ratio gearbox from being in an unstable meshing state when it is engaged, and to ensure that the small steam turbine can bear part of the induced draft fan load as soon as possible. For example, the meshing speed is 5215rpm, and the first preset speed can be 5230rpm at this time. The first preset speed can be set according to actual conditions.

[0157] S805: Switch to the valve position control mode and increase the opening of the small turbine steam inlet regulating valve until the output power of the asynchronous motor is positive.

[0158] Specifically, after the clutch engagement switch triggers the engagement signal for a certain period of time, the clutch fixed-speed ratio gearbox can be engaged stably, and the control system switches to the valve position control mode, gradually increasing the opening of the small steam turbine steam inlet regulating valve until the output power of the asynchronous motor is positive. At this time, the induced draft fan is only driven by the small steam turbine, and the asynchronous motor is in the generator working mode, transmitting the excess electrical energy to the plant power system.

[0159] In one embodiment, the control system is connected to the clutch engagement switch and switches to the valve position control system 60 seconds after the clutch engagement switch sends an engagement signal; in another embodiment, the staff can also switch manually, and the interval can actually be set according to actual conditions, and this application does not impose any restrictions on this.

[0160] The control method of the steam-electric dual-drive system of the induced draft fan provided in the present application starts the small steam turbine by starting the asynchronous motor and opening the steam inlet regulating valve of the small steam turbine; adopts the speed control mode to gradually increase the speed of the small steam turbine, and after the clutchable fixed speed ratio gearbox is engaged, adopts the valve position control mode to make the induced draft fan completely driven by the small steam turbine, thereby achieving a smooth start of the small steam turbine, and enabling the small steam turbine to quickly assume the load of the induced draft fan, thereby reducing the power supply of the factory power system.

[0161] On the basis of the above embodiments, further, Fig. 9 As shown, when in the closing stage, the control method of the induced draft fan steam-electric dual drive system provided by the present application also includes:

[0162] S901: Use valve position control mode to gradually reduce the opening of the small turbine steam inlet regulating valve until the output power of the asynchronous motor is negative;

[0163] Specifically, when in the closing stage, the control system adopts the valve position control mode to slowly reduce the opening of the small steam turbine steam inlet regulating valve to slowly reduce the output power of the small steam turbine until the output power of the asynchronous motor changes from a positive value to a negative value, and the asynchronous motor is in the motor working mode. At this time, the induced draft fan is driven by the small steam turbine and the asynchronous motor.

[0164] Slowly reducing the opening of the steam inlet regulating valve of a small steam turbine refers to intermittently reducing the opening of the steam inlet regulating valve of a small steam turbine. For example, the steam inlet regulating valve of a small steam turbine is reduced by a preset opening, and after a preset time interval, the operation of reducing the opening is repeated until the opening of the steam inlet regulating valve of the small steam turbine meets the requirements. Slowly reducing the opening of the steam inlet regulating valve of a small steam turbine can observe the changes of physical quantities such as the output power of the asynchronous motor in real time. When the physical quantities meet the requirements, the adjustment of the opening of the steam inlet regulating valve of the small steam turbine is stopped in time to prevent the opening from changing too much.

[0165] S902: Slowly and continuously reduce the opening of the small turbine steam inlet regulating valve until the output power of the asynchronous motor is within a preset range;

[0166] Specifically, the control system continues to slowly reduce the opening of the admission throttle valve of the small steam turbine, so that the output power P of the asynchronous motor satisfies f(t) + a < P < f(t) + b, where a < b, and a and b are positive numbers, t is the ratio of the unit load of the power generation system unit to the rated power of the unit, and f(t) is the functional relationship between the induced draft fan power and the unit load, which can be obtained by fitting the historical induced draft fan power and the corresponding unit load. In one embodiment, the function graph of f(t) is as Fig.10 shown, and the specific expression of f(t) varies according to the actual conditions of the power generation system unit and the induced draft fan, etc.

[0167] S903: Rapidly and continuously reduce the opening of the admission throttle valve of the small steam turbine until the speed of the small steam turbine is less than the second preset speed, so that the clutch engagement switch stops sending the engagement signal, and the clutchable constant speed ratio gearbox stops engaging;

[0168] Specifically, rapidly and continuously reducing the opening of the admission throttle valve of the small steam turbine is opposite to slowly reducing the opening of the admission throttle valve of the small steam turbine. By rapidly reducing the opening of the admission throttle valve of the small steam turbine, the speed of the small steam turbine is quickly reduced below the engagement speed, ensuring that the engagement signal disappears and the clutchable constant speed ratio gearbox stops engaging. At this time, the induced draft fan changes from being jointly driven by the small steam turbine and the asynchronous motor to being driven only by the asynchronous motor, and the output power of the asynchronous motor is negative. The second preset speed is less than the engagement speed, for example, 5000 rpm, and the value of the second preset speed can be set according to the actual situation, and this application does not limit this.

[0169] S904: Close the admission throttle valve of the small steam turbine to shut down the small steam turbine;

[0170] Specifically, the control system closes the admission throttle valve of the small steam turbine, and the small steam turbine stops running.

[0171] S905: Shut down the asynchronous motor.

[0172] Specifically, the control system shuts down the asynchronous motor, or manually disconnects the high-voltage switch to stop the asynchronous motor from running, and the steam-electric dual-drive system of the induced draft fan is shut down.

[0173] The control method for the steam-electric dual-drive system of the induced draft fan provided by this application realizes the shutdown of the steam-electric dual-drive system of the induced draft fan by gradually reducing the opening of the admission throttle valve of the small steam turbine in the valve position control mode, making the clutchable constant speed ratio gearbox stop engaging, and closing the small steam turbine and the asynchronous motor, preventing the sudden shutdown of the small steam turbine from causing a reduction in system stability and triggering a safety accident.

[0174] In the description of this specification, the description with reference to the terms "one embodiment", "a specific embodiment", "some embodiments", "for example", "example", "specific example", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0175] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A steam-electric dual-drive system for induced draft fans, characterized in that: include: induced draft fan; An asynchronous motor, coaxially connected to the induced draft fan and connected to the plant power system via a high-voltage switch; A small steam engine and a small steam engine steam inlet regulating valve connected to the small steam engine; A clutchable fixed speed ratio gearbox is arranged between the asynchronous motor and the small steam engine and is coaxially connected to the asynchronous motor and the small steam engine; A clutch engagement switch, arranged on the clutchable fixed speed ratio gearbox; A control system connected to the asynchronous motor and the small steam turbine steam inlet regulating valve to control the opening and closing of the asynchronous motor and adjust the opening of the small steam turbine steam inlet regulating valve according to the current operation stage and the pre-obtained target opening model; The control modes of the control system include: valve position control mode and speed control mode; the control system includes: A judging unit, used to judge whether the running condition of the asynchronous motor meets the preset locomotive side starting condition; A control unit, when the operating condition meets the preset maintenance side start condition, is used to obtain the current operating condition data of the system, start the valve position control mode, and adjust the opening of the small steam turbine steam inlet regulating valve according to the operating condition data and the pre-obtained target opening model; The mode switching unit is used to switch the valve position control mode to the speed control mode so that the small steam engine keeps running at the meshing speed.

2. The induced draft fan steam-electric dual drive system according to claim 1 is characterized in that: The control system further comprises: a closing unit, which is used to close the steam inlet regulating valve of the small steam turbine when the operating condition does not meet the preset locomotive side start condition.

3. The induced draft fan steam-electric dual drive system according to claim 1 is characterized in that: Also includes: A power detection device is connected to the asynchronous motor.

4. The induced draft fan steam-electric dual drive system according to claim 1 is characterized in that: The induced draft fan is a constant speed device, and the load is adjusted by changing the blade angle on the hub.

5. A control method for a steam-electric dual-drive system of an induced draft fan, characterized in that: include: Receive control instructions; Determining the operation stage of the steam-electric dual-drive system of the induced draft fan according to the control instruction; The operation phase includes a startup phase, a shutdown phase and an accident phase; If the operation stage is an accident stage, the opening of the small steam turbine steam inlet regulating valve is adjusted according to the pre-obtained target opening model; The step of adjusting the opening of the small steam turbine steam inlet regulating valve according to the pre-obtained target opening model includes: detecting the operating status of the asynchronous motor and determining whether the operating status meets the preset locomotive side start condition; If the operating conditions meet the preset maintenance side start conditions, the valve position control mode is adopted to obtain the current operating condition data of the system, and the opening of the small steam turbine steam inlet regulating valve is adjusted according to the operating condition data and the pre-obtained target opening model; switch to the speed control mode to keep the small steam turbine running at the engaged speed.

6. The control method of the steam-electric dual-drive system of the induced draft fan according to claim 5 is characterized in that: The step of adjusting the opening of the small steam turbine steam inlet regulating valve according to the operating condition data and a pre-obtained target opening model includes: At least one of a small steam turbine steam inlet pressure, a small steam turbine steam inlet temperature, a small steam turbine steam inlet flow rate, a small steam turbine back pressure, a small steam turbine exhaust temperature, a small steam turbine speed, a unit load, and an asynchronous motor power is obtained as operating condition data; Inputting the operating condition data into the target opening model to obtain the target opening of the small steam turbine steam inlet regulating valve; The opening of the small steam turbine steam inlet regulating valve is adjusted to the target opening.

7. The control method of the induced draft fan steam-electric dual drive system according to claim 5, characterized in that: Also includes: If the operating conditions do not meet the preset maintenance side start conditions, close the small steam turbine steam inlet regulating valve.

8. The control method of the induced draft fan steam-electric dual drive system according to claim 5, characterized in that: If the operation phase is a startup phase, it also includes: Turning on the asynchronous motor and opening the steam inlet regulating valve of the small steam engine to start the small steam engine; Use the speed control mode to adjust the opening of the steam inlet valve of the small steam turbine so that the small steam turbine can warm up at the preset warm-up speed for the first preset time; Increasing the speed of the small steam engine to the rated speed, so that the small steam engine maintains the rated speed for a second preset time; Increasing the speed of the small steam engine to a first preset speed, so that the clutch engagement switch triggers an engagement signal, and the clutch fixed speed ratio gearbox is engaged; Switch to the valve position control mode and increase the opening of the small steam turbine steam inlet regulating valve until the output power of the asynchronous motor is positive.

9. The control method of the induced draft fan steam-electric dual drive system according to claim 5, characterized in that: If the operation phase is a shutdown phase, it also includes: Use valve position control mode to gradually reduce the opening of the small turbine steam inlet regulating valve until the output power of the asynchronous motor is negative; Slowly and continuously reducing the opening of the small steam turbine steam inlet regulating valve until the output power of the asynchronous motor is within a preset range; Rapidly and continuously reducing the opening of the steam inlet regulating valve of the small steam turbine until the speed of the small steam turbine is less than the second preset speed, so that the clutch engagement switch stops sending the engagement signal and the clutchable fixed speed ratio gearbox stops engaging; Closing the steam inlet regulating valve of the small steam turbine to shut down the small steam turbine; The asynchronous motor is switched off.

10. The control method of the induced draft fan steam-electric dual drive system according to claim 5, characterized in that: Also includes: Collecting historical opening data and corresponding operating condition data of the steam inlet regulating valve of the small steam turbine; Normalizing the working condition data and dividing them into a training set and a validation set; The training set and the validation set are used to train the preset target opening model.

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