Steam and electricity dual drive induced draft fan system and control method thereof

Abstract

This application relates to the field of thermal power generation technology and discloses a steam-electric dual-drive induced draft fan system and its control method. This application achieves full automation of the entire process from electric start-up and seamless steam-electric switching to combined speed and blade regulation by coordinating the control of the variable-speed clutch, asynchronous motor / generator, and induced draft fan blades at different load stages. During low load stages, the induced draft fan is driven by the electric motor, and the blades adjust the output to ensure stable operation of the unit even when steam conditions are insufficient. In the intermediate load range, the variable-speed clutch uses speed regulation as the primary means of maintaining negative pressure in the furnace, with the blade opening only slowly changing with the unit load. This ensures the blades are always at a highly efficient and stable opening, effectively avoiding abnormalities such as surge and stall caused by excessively small blade openings, significantly improving the reliability and economy of the induced draft fan operation. When the unit drops to a low load again, it automatically reverts to electric motor drive, ensuring continuous and stable operation before shutdown.

Description

Technical Field

[0001] This application relates to the field of thermal power generation technology, specifically to a steam-electric dual-drive induced draft fan system and its control method. Background Technology

[0002] Driven by carbon emission reduction targets, the installed capacity of new energy sources such as wind power and photovoltaics has experienced explosive growth and will gradually become my country's main power source in the future. During this energy structure adjustment and transformation process, the role of coal-fired power units is shifting from base load power to a supporting and regulating power source. Since the launch of the first batch of long-term settlement operations in the electricity spot market, spot trading has placed higher demands on the peak-shaving, deep peak-regulation, and flexible operation capabilities of generating units.

[0003] Under deep peak-shaving mode, the induced draft fans of thermal power units face severe challenges. On the one hand, due to excessively low blade opening, mismatch between system resistance and flow rate, and increased flow deviation on both sides, surge and stall due to draft are easily triggered, seriously threatening the operational reliability of the induced draft fans. On the other hand, the induced draft fans deviate from the optimal economic operating point for a long time, operating in the inefficient zone, resulting in increasingly prominent problems of high energy consumption and poor economy. In addition, the existing induced draft fan drive methods are mostly single electric motor drive or single steam turbine drive, which makes it difficult to switch flexibly at full load, and cannot simultaneously ensure stable start-up at low loads and efficient operation at medium and high loads. Summary of the Invention

[0004] This application provides a steam-electric dual-drive induced draft fan system and its control method to solve the problems of poor reliability and low economy of induced draft fans in the prior art during deep peak shaving of thermal power units.

[0005] In a first aspect, this application provides a control method for a dual-drive steam-electric induced draft fan system, the method comprising: During the initial startup phase of the unit to the first preset load stage, the control speed clutch disengages the turbine from the shaft system, and the asynchronous electric motor / generator drives the induced draft fan as the electric motor. The output of the induced draft fan is adjusted by the opening of the moving blades. The turbine, the asynchronous electric motor / generator, and the induced draft fan are coaxially connected. When the unit load rises to the first preset load and the steam turbine inlet conditions are met, the steam turbine is started to run. After the steam turbine speed exceeds the asynchronous motor / generator speed, the speed change clutch is controlled to engage the shaft system, and the drive end is switched from the asynchronous motor / generator to the steam turbine. When the unit load is between the first preset load and the second preset load, the speed of the induced draft fan is adjusted by the speed change clutch according to the change of furnace negative pressure, so that the furnace negative pressure is maintained within the set range. At the same time, the opening of the moving blades is controlled to follow the unit load and be adjusted at a set rate. The second preset load is greater than the first preset load. When the unit load drops below the first preset load and the steam inlet conditions are not met, the speed change clutch is disengaged from the shaft system, so that the steam turbine enters a hot standby state, and the asynchronous motor / generator is used as the motor to drive the induced draft fan until the unit stops operating.

[0006] In one optional implementation, when the unit load is within the range of the first preset load to the second preset load, the induced draft fan speed is adjusted via the speed-changing clutch according to the change in furnace negative pressure, so that the furnace negative pressure is maintained within the set range. Simultaneously, the blade opening is controlled to adjust at a set rate following the unit load, including: When the unit load is in the range between the first preset load and the second preset load, the speed adjustment of the induced draft fan is used by the speed change clutch as the main adjustment means to maintain the negative pressure in the furnace. The speed of the induced draft fan is automatically adjusted according to the real-time feedback signal of the negative pressure in the furnace so that the negative pressure in the furnace is maintained within the set range. Using the adjustment of the blade opening as an auxiliary adjustment means, the blade opening is set as a function of the unit load, so that the blade opening increases or decreases at a preset rate in accordance with the rise and fall of the unit load.

[0007] In an optional implementation, the method further includes: When the unit load is within the range of the first preset load to the second preset load, the dispatching AGC is activated. When the load reduction instruction is received from the dispatch AGC and deep peak shaving is performed, the power generation of the unit is stored in the first energy storage device at a preset proportion.

[0008] In an optional implementation, the method further includes: When the first energy storage device is saturated, the steam flow rate of the steam turbine is increased so that the input power of the steam turbine is greater than the required power of the induced draft fan, thereby driving the asynchronous motor / generator to exceed its synchronous speed and switching the asynchronous motor / generator from motor mode to generator mode.

[0009] In one alternative implementation, the generated energy from the asynchronous motor / generator is stored in a second energy storage device via the plant power bus and the energy storage converter.

[0010] Secondly, this application provides a steam-electric dual-drive induced draft fan system, the system comprising: a steam turbine, an asynchronous motor / generator, an induced draft fan, a speed-changing clutch, and a unit control system, wherein... The steam turbine, the asynchronous electric motor / generator, and the induced draft fan are coaxially connected. The steam turbine selectively engages or disengages from the coaxial shaft system via the speed-changing clutch; The unit control system is communicatively connected to the steam turbine, the asynchronous electric motor / generator, the induced draft fan, and the variable speed clutch, respectively. The unit control system is used to execute the control method of the steam-electric dual-drive induced draft fan system in the first aspect or any corresponding embodiment.

[0011] In one optional embodiment, the system further includes: a thermal power unit, a hybrid energy storage control system, and a first energy storage device, wherein, The hybrid energy storage control system is communicatively connected to the unit control system; The hybrid energy storage control system is also connected to the thermal power unit and the first energy storage device respectively; The hybrid energy storage control system is used to store a preset proportion of the power generation of the thermal power unit in the first energy storage device when it receives the load reduction instruction from the dispatch AGC and performs deep peak shaving.

[0012] In one optional embodiment, the system further includes: a plant power bus, an energy storage converter, and a second energy storage device, wherein, The AC side of the energy storage converter is connected to the plant power bus, and the DC side of the energy storage converter is connected to the second energy storage device. The asynchronous motor / generator is connected to the plant power bus.

[0013] In one alternative implementation, the system further includes a circuit breaker connected between the asynchronous motor / generator and the plant power bus.

[0014] In one alternative implementation, The first energy storage device is a lithium iron phosphate battery energy storage device; The second energy storage device is a lithium titanate battery power type energy storage device.

[0015] This application achieves full automation of the entire process from electric start-up and seamless steam-electric switching to combined speed-blade regulation by coordinating the control of the variable-speed clutch, asynchronous motor / generator, and induced draft fan blades at different load stages. During low-load stages, the induced draft fan is driven by the electric motor, and the blades adjust their output to ensure stable operation even when steam conditions are insufficient. In the intermediate load range, the variable-speed clutch uses speed regulation as the primary means of maintaining negative pressure in the furnace, with the blade opening only slowly changing with the unit load. This ensures the blades are always at a highly efficient and stable opening, effectively avoiding surge, stall, and other abnormalities caused by excessively small blade openings, significantly improving the reliability and economy of the induced draft fan. When the unit drops to a low load again, it automatically reverts to electric motor drive, ensuring continuous and stable operation before shutdown. This method offers flexible adjustment and rapid response, making it particularly suitable for deep peak shaving and wide-load operation scenarios in thermal power units. While ensuring the safe and efficient operation of the induced draft fan, it significantly improves the overall economy of the unit. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the specific embodiments of this application or the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0017] Figure 1 This is a schematic flowchart of the control method for a dual-drive steam-electric induced draft fan system according to an embodiment of this application; Figure 2 This is a structural schematic diagram of a steam-electric dual-drive induced draft fan system according to an embodiment of this application. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] It is understood that before using the technical solutions disclosed in the various embodiments of this application, users should be informed of the types, scope of use, and usage scenarios of the personal information involved in this application in an appropriate manner in accordance with relevant laws and regulations, and user authorization should be obtained.

[0020] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0021] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can also refer to the internal connection of two components; and they can refer to a wireless connection or a wired connection. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] It should be noted that the term "unit" in this application refers to a coal-fired power unit, mainly including the boiler, turbine generator, and its auxiliary systems. The unit's load (i.e., power generation) is controlled by dispatch AGC commands. Dispatch AGC is an automatic power generation control command issued by the power grid dispatch center. Based on real-time changes in the power demand of the entire grid, it sends target power values ​​to the unit, and the unit's control system automatically adjusts its output accordingly. Changes in the unit's load directly affect key operating indicators such as boiler steam parameters (e.g., the pressure and temperature of the steam extracted from the cold section of the reheater) and furnace negative pressure. The induced draft fan, as an important auxiliary machine of the unit, is used to extract flue gas from the furnace and maintain the furnace negative pressure within a set range; its operating status directly affects the unit's safety and economy.

[0023] This application provides a control method for a dual-drive steam-electric induced draft fan system, such as... Figure 1 As shown, it includes the following steps: Step S1: When the unit starts up to the first preset load stage, the speed change clutch is controlled to disengage the turbine from the shaft system, and the asynchronous motor / generator is used as the motor to drive the induced draft fan. The output of the induced draft fan is adjusted by the opening of the moving blades. The turbine, asynchronous motor / generator and induced draft fan are coaxially connected.

[0024] Specifically, during the unit startup phase, the load gradually increases from zero to the first preset load (e.g., 30% of rated load). During this phase, the speed-changing clutch keeps the turbine disengaged from the coaxial shaft system, and the turbine does not participate in driving. At this time, the asynchronous motor / generator draws power from the plant's auxiliary power bus and directly drives the induced draft fan. The induced draft fan's speed remains constant (e.g., rated speed), and its output is achieved by adjusting the blade opening. When it is necessary to increase the induced draft fan output, the blade opening is increased; conversely, the blade opening is decreased. It should be noted that the turbine, asynchronous motor / generator, and induced draft fan are coaxially connected via a coupling, but when the speed-changing clutch is disengaged, the turbine rotor separates from the shaft system and does not rotate with the shaft system.

[0025] Step S2: When the unit load rises to the first preset load and the steam turbine inlet conditions are met, start the steam turbine to start. After the steam turbine speed exceeds the asynchronous motor / generator speed, control the speed change clutch to engage the shaft system and switch the drive end from the asynchronous motor / generator to the steam turbine.

[0026] Specifically, when the unit load rises to the first preset load (e.g., 30% of rated load), the steam extraction quality of the cold section of the boiler reheater meets the turbine inlet steam conditions. At this point, the turbine is started and begins to accelerate. As the turbine speed gradually increases and exceeds the synchronous speed of the asynchronous motor / generator, the speed-changing clutch automatically engages, connecting the turbine to the coaxial shaft system. At this point, the drive end switches from the asynchronous motor / generator to the turbine, which drives both the induced draft fan and the asynchronous motor / generator. The exhaust steam from the turbine after it has completed its work is connected to the external steam supply system or the unit's auxiliary steam system via pipelines.

[0027] Step S3: When the unit load is in the range of the first preset load to the second preset load, the speed of the induced draft fan is adjusted by the speed change clutch according to the change of the furnace negative pressure, so that the furnace negative pressure is maintained within the set range. At the same time, the opening of the moving blades is controlled to follow the unit load and be adjusted at a set rate. The second preset load is greater than the first preset load.

[0028] Specifically, when the unit load is between the first preset load (e.g., 30% of rated load) and the second preset load (e.g., 100% of rated load), coordinated regulation control is implemented. Specifically, based on the actual changes in furnace negative pressure, the induced draft fan speed is adjusted in real time via a variable-speed clutch. For example, when the furnace negative pressure deviates from the set range (e.g., the target value is around -100 Pa), the variable-speed clutch automatically changes the transmission ratio, thereby changing the induced draft fan speed and restoring the furnace negative pressure to the set range. Simultaneously, the induced draft fan's blade opening is controlled to follow changes in unit load and adjusted at a set rate. For example, when the unit load increases, the blade opening gradually increases at a certain rate (e.g., 0.5% per minute); when the unit load decreases, the blade opening gradually decreases at a certain rate. Through this coordinated regulation, the induced draft fan can maintain stable operation under different loads. It should be noted that the second preset load is greater than the first preset load, and the second preset load is usually the unit's rated load.

[0029] Step S4: When the unit load drops below the first preset load and the steam inlet conditions are not met, the control speed change clutch is disengaged from the shaft system, so that the steam turbine enters the hot standby state, and the asynchronous motor / generator is used as the motor to drive the induced draft fan until the unit is shut down.

[0030] Specifically, when the unit load drops again until it falls below the first preset load (e.g., below 30% of the rated load) and the quality of the steam extracted from the cold section of the boiler reheater can no longer meet the turbine's steam inlet conditions, the control speed change clutch automatically disengages, separating the turbine from the coaxial shaft system, and the turbine enters hot standby mode (maintaining turning gear and lubrication). At this time, the asynchronous motor / generator resumes to draw power from the plant power bus as a motor, independently driving the induced draft fan to continue running until the unit is completely shut down.

[0031] This application achieves full automation of the entire process from electric start-up and seamless steam-electric switching to combined speed-blade regulation by coordinating the control of the variable-speed clutch, asynchronous motor / generator, and induced draft fan blades at different load stages. During low-load stages, the induced draft fan is driven by the electric motor, and the blades adjust their output to ensure stable operation even when steam conditions are insufficient. In the intermediate load range, the variable-speed clutch uses speed regulation as the primary means of maintaining negative pressure in the furnace, with the blade opening only slowly changing with the unit load. This ensures the blades are always at a highly efficient and stable opening, effectively avoiding surge, stall, and other abnormalities caused by excessively small blade openings, significantly improving the reliability and economy of the induced draft fan. When the unit drops to a low load again, it automatically reverts to electric motor drive, ensuring continuous and stable operation before shutdown. This method offers flexible adjustment and rapid response, making it particularly suitable for deep peak shaving and wide-load operation scenarios in thermal power units. While ensuring the safe and efficient operation of the induced draft fan, it significantly improves the overall economy of the unit.

[0032] In one optional implementation, step S3 specifically includes the following steps: Step S311: When the unit load is in the range of the first preset load to the second preset load, the speed of the induced draft fan is adjusted by the speed change clutch as the main adjustment means to maintain the negative pressure in the furnace. The speed of the induced draft fan is automatically adjusted according to the real-time feedback signal of the negative pressure in the furnace so that the negative pressure in the furnace is maintained within the set range.

[0033] Specifically, when the unit load is between the first preset load (e.g., 30% of rated load) and the second preset load (e.g., 100% of rated load), the adjustment of the induced draft fan speed by the variable speed clutch is used as the main control method to maintain the furnace negative pressure. Specifically, the real-time value of the furnace negative pressure is continuously collected by a pressure transmitter and transmitted to the unit control system. The control system compares the measured negative pressure with the set target value (e.g., -100 Pa) and calculates the deviation. Based on this deviation, the control system sends a speed adjustment command to the variable speed clutch, automatically changing the transmission ratio of the clutch, thereby adjusting the induced draft fan speed in real time. When the furnace negative pressure is lower than the set value (excessive negative pressure), the induced draft fan speed is appropriately increased to increase the suction force; when the furnace negative pressure is higher than the set value (excessive negative pressure or even positive pressure), the induced draft fan speed is appropriately decreased to reduce the suction force. Through this closed-loop regulation, the furnace negative pressure is always maintained within the set target range, ensuring the safe and stable operation of the boiler.

[0034] Step S312: Using the adjustment of the blade opening as an auxiliary adjustment means, the blade opening is set as a function of the unit load, so that the blade opening increases or decreases at a preset rate following the rise and fall of the unit load.

[0035] Specifically, while the induced draft fan speed serves as the primary adjustment method to maintain the furnace negative pressure, the adjustment of the induced draft fan blade opening is used as an auxiliary adjustment method. Specifically, the blade opening does not directly respond to instantaneous fluctuations in furnace negative pressure, but is set as a function of the unit load. That is, based on the current unit load value, the corresponding target blade opening value is calculated through a preset functional relationship, and then the blade opening is slowly adjusted to this target value at a certain set rate (e.g., 0.5% opening per minute). When the unit load increases, the blade opening gradually increases according to the set rate; when the unit load decreases, the blade opening gradually decreases according to the set rate. Because the blade opening only changes slowly with macroscopic load changes and does not participate in rapid negative pressure adjustment, it can effectively avoid falling into an inefficient and unstable operating range due to frequent blade movement or excessively small opening. Throughout the entire coordinated control process, speed regulation undertakes the task of rapid and precise control of negative pressure, while the blade opening is maintained within a relatively stable and efficient opening range (e.g., 60%–85%). The two work together to ensure the stability of the furnace negative pressure and improve the operational reliability and economy of the induced draft fan.

[0036] Through the steps S311 and S312 described above, the coordinated regulation of the induced draft fan speed and the blade opening is achieved: speed regulation is the primary method, responding quickly to negative pressure fluctuations; blade regulation is secondary, following the slow changes in load. This coordinated control strategy is particularly suitable for wide-load operation scenarios such as deep peak shaving of thermal power units, and can significantly reduce the risk of induced draft fan stall and surge, while improving efficiency under all operating conditions.

[0037] In one optional implementation, the control method for the dual-drive steam-electric induced draft fan system further includes the following steps: Step S321: When the unit load is in the range of the first preset load to the second preset load, the dispatching AGC is put into operation.

[0038] Specifically, when the unit load stabilizes between the first preset load (e.g., 30% of rated load) and the second preset load (e.g., 100% of rated load), the unit is ready to participate in the grid's automatic generation control (AGC). At this time, the dispatch AGC is put into operation, enabling the unit to receive load instructions issued in real time by the grid dispatch center and automatically adjust the unit output according to the instructions to meet the grid's frequency regulation and peak shaving needs.

[0039] Step S322: When the load reduction instruction from the dispatch AGC is received and deep peak shaving is performed, the power generation of the unit at a preset proportion is stored in the first energy storage device.

[0040] Specifically, during deep peak shaving of the generating unit, if a load reduction command is received from the dispatch AGC, the unit control system will initiate the energy storage peak shaving process while coordinating the rapid reduction of the thermal power unit's output (e.g., reducing fuel consumption, shutting down turbine control valves). Specifically, according to a preset ratio (e.g., a coefficient dynamically determined based on the magnitude of the load reduction command and the remaining capacity of the current energy storage device), a portion of the thermal power unit's generated electricity is transmitted to the first energy storage device (e.g., lithium iron phosphate battery energy storage) via the plant power bus and energy storage converter. In this way, the actual grid-connected electricity of the unit equals the total generated electricity minus the electricity stored in the first energy storage device, thus responding quickly and flexibly to the dispatch load reduction command. The first energy storage device acts as an energy buffer in this process, avoiding thermal stress and operational instability problems caused by large and drastic load reductions in the unit itself.

[0041] In step S323, once the first energy storage device is saturated, the steam flow rate into the turbine is increased to make the turbine's input power greater than the induced draft fan's required power. This drives the asynchronous motor / generator to exceed its synchronous speed, switching the asynchronous motor / generator from motor mode to generator mode. The generated energy from the asynchronous motor / generator is stored in the second energy storage device via the plant power bus and energy storage converter.

[0042] Specifically, when the state of charge of the first energy storage device reaches saturation (i.e., it can no longer be charged), if the load reduction command has not yet been completed or if it is necessary to further enhance the energy storage peak-shaving capacity, then the second stage of energy storage operation will be initiated. The specific control method is as follows: First, the steam flow rate into the turbine is increased by widening the steam inlet regulating valve. The turbine draws more steam from the cold section of the boiler reheater, thus increasing its input power. When the turbine's input power exceeds the shaft power currently required by the induced draft fan, the excess power is transmitted to the coaxial system, driving the rotor speed of the asynchronous motor / generator to increase. Once the asynchronous motor / generator's speed exceeds its synchronous speed (for example, for a 10kV, 50Hz asynchronous motor, the synchronous speed is typically 1000 r / min or 3000 r / min), the asynchronous motor / generator automatically switches from motor mode to generator mode, beginning to convert excess mechanical energy on the shaft system into electrical energy.

[0043] The generated electrical energy is alternating current (AC), with its frequency and amplitude varying with the rotational speed. This energy is first transmitted to the 10kV busbar of the plant's auxiliary power supply via the output terminals of the asynchronous motor / generator, cables, and circuit breakers. Then, it undergoes rectification, filtering, and voltage conversion through an energy storage converter, ultimately being stored as direct current in a second energy storage device (e.g., a lithium titanate battery power storage system). Due to the high power density and rapid charging / discharging characteristics of this second energy storage device, it can quickly absorb the instantaneous electrical energy generated by the asynchronous motor / generator, thereby further enhancing the unit's energy storage capacity during deep peak shaving and strengthening its support for grid frequency regulation and peak shaving.

[0044] Through the above steps S321 to S323, this embodiment not only utilizes the first energy storage device to absorb the excess power generated by the unit, but also innovatively converts the excess shaft power in the turbine-induced draft fan system into electrical energy and stores it in the second energy storage device, thus achieving a dual improvement in the energy storage and peak-shaving capacity of the thermal power unit.

[0045] This application provides a dual-drive steam-electric induced draft fan system, such as... Figure 2 As shown, the system includes: a steam turbine, an asynchronous electric motor / generator, an induced draft fan, a variable speed clutch, and a unit control system. The steam turbine, asynchronous electric motor / generator, and induced draft fan are coaxially connected; the steam turbine selectively engages or disengages from the coaxial shaft system via the variable speed clutch; the unit control system is communicatively connected to the steam turbine, asynchronous electric motor / generator, induced draft fan, and variable speed clutch, and is used to execute the control method of the steam-electric dual-drive induced draft fan system described in the above embodiments.

[0046] Specifically, the steam turbine, asynchronous motor / generator, and induced draft fan are sequentially coaxially connected via couplings to form a unified shaft system. The steam turbine selectively engages or disengages from the coaxial shaft system via a speed-changing clutch. When the speed-changing clutch is engaged, the turbine rotor is connected to the shaft system, driving the asynchronous motor / generator and induced draft fan to rotate together; when the speed-changing clutch is disengaged, the steam turbine is separated from the shaft system and is in a hot standby state, at which point the asynchronous motor / generator can independently drive the induced draft fan as a motor.

[0047] The unit's control system is communicatively connected to the steam turbine, asynchronous motor / generator, induced draft fan, and variable speed clutch (in... Figure 2 (Not shown in the image). The unit control system is used to execute the control method of the steam-electric dual-drive induced draft fan system described in any of the foregoing embodiments. Specifically, the unit control system can automatically control the engagement and disengagement of the variable speed clutch according to the unit load stage and steam inlet conditions, control the switching of the asynchronous motor / generator between motor and generator states, and achieve coordinated adjustment of the induced draft fan speed and blade opening. Through the above structural configuration and control functions, this system can achieve fully automated control from electric start-up, steam-electric switching, coordinated operation to shutdown recovery, improve the operational reliability and economy of the induced draft fan, and provide a hardware foundation for subsequent energy storage operations during deep peak shaving.

[0048] Furthermore, the asynchronous motor / generator shares an independent lubrication system with the induced draft fan, eliminating the need for the turbine to provide lubrication. The turbine is equipped with a turning gear and its control system to drive the induced draft fan in turning motion. This turning gear has automatic engagement and disengagement functions, and engagement is prohibited when the turbine has no lubrication or the lubrication pressure is below normal. The variable speed clutch consists of a gearbox and a clutch. Its low-speed shaft uses a hollow shaft with a flexible rod design; the clutch is installed on the non-shaft extension end of the low-speed shaft of the gearbox and is integrated into the gearbox as a single unit. This variable speed clutch not only has a speed-changing function but also enables automatic engagement and disengagement.

[0049] It should be pointed out that, Figure 2 Other components shown can be selectively configured as needed to further expand the system's energy storage and peak-shaving capabilities. This embodiment only describes the core shafting and control components, but those skilled in the art will understand that the aforementioned extended components can be integrated with... Figure 2 The system shown is combined to achieve a complete and synergistic improvement in energy storage peak-shaving capabilities.

[0050] The main parameters of each piece of equipment under rated operating conditions are shown in Table 1: Table 1

[0051] In one alternative implementation, such as Figure 2As shown, the system also includes: a thermal power unit, a hybrid energy storage control system, and a first energy storage device. The hybrid energy storage control system is communicatively connected to the thermal power unit control system; the hybrid energy storage control system is also connected to both the thermal power unit and the first energy storage device; the hybrid energy storage control system is used to store a preset proportion of the generated electricity from the thermal power unit in the first energy storage device when it receives a dispatch AGC load reduction command and performs deep peak shaving.

[0052] Specifically, the thermal power unit, as the main power generation entity, outputs electrical energy into the power grid through the main transformer, and simultaneously supplies power to on-site equipment such as asynchronous motors / generators through the plant auxiliary power bus. The hybrid energy storage control system is communicatively connected to the unit control system to receive energy storage dispatch instructions issued by the unit control system and to provide feedback on the operating status of the energy storage system (such as state of charge, charging and discharging power, etc.).

[0053] The hybrid energy storage control system is also connected to both the thermal power unit and the first energy storage device. It should be noted that this "connection" includes both control signal connections and power transmission connections. Specifically, the hybrid energy storage control system is connected to the electrical output monitoring unit of the thermal power unit via control signal lines to obtain the real-time power generation of the thermal power unit; simultaneously, the hybrid energy storage control system is connected to the battery management system of the first energy storage device via control signal lines to monitor the state of charge of the first energy storage device and issue charging and discharging commands. In the power transmission path, the first energy storage device is connected to the plant power bus of the thermal power unit, thus forming an electrical connection with the power generation output of the thermal power unit.

[0054] The hybrid energy storage control system is used to store a preset proportion of the generated electricity from thermal power units in a first energy storage device when receiving a load reduction command from the dispatch AGC and performing deep peak shaving. The specific control process is as follows: When the dispatch AGC issues a load reduction command, the unit control system, while coordinating the rapid reduction of output from the thermal power units, sends an energy storage activation command to the hybrid energy storage control system. The hybrid energy storage control system determines the proportion of generated electricity to be stored based on the magnitude of the load reduction command and the remaining capacity of the first energy storage device (for example, setting the charging power according to a certain proportion of the power reduction value required by the load reduction command). Subsequently, the hybrid energy storage control system activates the charging mode, converting the AC power transmitted from the thermal power units via the plant auxiliary power bus into DC power and charging it into the first energy storage device. In this way, the actual grid-connected power of the unit equals the total generated electricity of the thermal power units minus the amount of electricity stored in the first energy storage device, thus enabling a rapid and flexible response to the dispatch load reduction command.

[0055] In this embodiment, the first energy storage device is preferably an energy-type energy storage device (such as a lithium iron phosphate battery energy storage device), which has a high energy density and is suitable for absorbing and storing excess power generated by the unit during deep peak shaving. Through the above configuration, this system, while achieving efficient and reliable operation of the induced draft fan, further possesses energy storage and peak shaving capabilities, effectively improving the flexibility and economy of thermal power units participating in deep peak shaving of the power grid.

[0056] In one alternative implementation, such as Figure 2 As shown, the system also includes: a plant power bus, an energy storage converter, and a second energy storage device. The AC side of the energy storage converter is connected to the plant power bus, and the DC side of the energy storage converter is connected to the second energy storage device. An asynchronous motor / generator is connected to the plant power bus. The system also includes: a circuit breaker connected between the asynchronous motor / generator and the plant power bus.

[0057] Specifically, the plant auxiliary power bus is an AC distribution bus drawn from the thermal power unit's plant auxiliary power system, used to supply power to large auxiliary equipment such as induced draft fans and feedwater pumps. In this embodiment, a 10kV plant auxiliary power bus is used. The outgoing terminals of the asynchronous motor / generator are connected to the 10kV plant auxiliary power bus via cables and circuit breakers, thereby realizing the exchange of electrical energy with the plant's power grid: when the asynchronous motor / generator is running as a motor, it draws power from the 10kV plant auxiliary power bus to drive the induced draft fan; when the asynchronous motor / generator is running as a generator, the generated electrical energy is sent back to the 10kV plant auxiliary power bus via cables.

[0058] An energy storage converter is a bidirectional power conversion device. Its AC side is connected to the 10kV busbar of the plant's auxiliary power supply via a cable, while its DC side is connected to a second energy storage device via a DC cable. The energy storage converter can achieve bidirectional AC-DC conversion: in charging mode, it rectifies the AC power on the 10kV busbar of the plant's auxiliary power supply into DC power and charges the second energy storage device according to the set voltage and current; in discharging mode, it inverts the DC power released by the second energy storage device into AC power synchronized with the 10kV busbar of the plant's auxiliary power supply, feeds it back to the busbar, supplies it to other equipment, or ultimately sends it to the power grid through the main transformer.

[0059] The second energy storage device is preferably a power-type energy storage device, such as a lithium titanate battery power-type energy storage device. Compared with energy-type energy storage, power-type energy storage has higher power density and faster charge and discharge response speed, making it particularly suitable for absorbing electrical energy with strong instantaneous power fluctuations. In this system, when the turbine inlet steam flow increases during deep peak shaving and the asynchronous motor / generator switches to generating mode, the generated electrical energy has the characteristics of high instantaneous power and short duration. By storing it in the second energy storage device through the 10kV busbar of the plant power supply and the energy storage converter, it can effectively smooth out power surges and realize energy recovery and utilization.

[0060] With the above configuration, this system can not only absorb the excess power generation of the thermal power unit using the first energy storage device, but also quickly absorb the transient power generation generated by the asynchronous motor / generator during the steam-electric switching process using the second energy storage device, thereby significantly improving the overall energy storage peak-shaving capability of the unit and the response speed to grid power fluctuations.

[0061] Although embodiments of this application have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of this application, and all such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A control method of a steam turbine and electric motor dual drive induced draft fan system, characterized by, The method includes: During the initial startup phase of the unit to the first preset load stage, the control speed clutch disengages the turbine from the shaft system, and the asynchronous electric motor / generator drives the induced draft fan as the electric motor. The output of the induced draft fan is adjusted by the opening of the moving blades. The turbine, the asynchronous electric motor / generator, and the induced draft fan are coaxially connected. When the unit load rises to the first preset load and the steam turbine inlet conditions are met, the steam turbine is started to run. After the steam turbine speed exceeds the asynchronous motor / generator speed, the speed change clutch is controlled to engage the shaft system, and the drive end is switched from the asynchronous motor / generator to the steam turbine. When the unit load is between the first preset load and the second preset load, the speed of the induced draft fan is adjusted by the speed change clutch according to the change of furnace negative pressure, so that the furnace negative pressure is maintained within the set range. At the same time, the opening of the moving blades is controlled to follow the unit load and be adjusted at a set rate. The second preset load is greater than the first preset load. When the unit load drops below the first preset load and the steam inlet conditions are not met, the speed change clutch is disengaged from the shaft system, so that the steam turbine enters a hot standby state, and the asynchronous motor / generator is used as the motor to drive the induced draft fan until the unit stops operating.

2. The control method of the gas turbine and electric dual drive induced draft fan system according to claim 1, characterized by, When the unit load is within the range of the first preset load to the second preset load, the induced draft fan speed is adjusted via the speed-changing clutch according to the change in furnace negative pressure, so that the furnace negative pressure is maintained within the set range. Simultaneously, the blade opening is controlled to adjust at a set rate following the unit load, including: When the unit load is in the range between the first preset load and the second preset load, the speed adjustment of the induced draft fan is used by the speed change clutch as the main adjustment means to maintain the negative pressure in the furnace. The speed of the induced draft fan is automatically adjusted according to the real-time feedback signal of the negative pressure in the furnace so that the negative pressure in the furnace is maintained within the set range. Using the adjustment of the blade opening as an auxiliary adjustment means, the blade opening is set as a function of the unit load, so that the blade opening increases or decreases at a preset rate in accordance with the rise and fall of the unit load.

3. The control method for the steam-electric dual-drive induced draft fan system according to claim 1, characterized in that, The method further includes: When the unit load is within the range of the first preset load to the second preset load, the dispatching AGC is activated. When the load reduction instruction is received from the dispatch AGC and deep peak shaving is performed, the power generation of the unit is stored in the first energy storage device at a preset proportion.

4. The control method for the dual-drive steam-electric induced draft fan system according to claim 3, characterized in that, The method further includes: When the first energy storage device is saturated, the steam flow rate of the steam turbine is increased so that the input power of the steam turbine is greater than the required power of the induced draft fan, thereby driving the asynchronous motor / generator to exceed its synchronous speed and switching the asynchronous motor / generator from motor mode to generator mode.

5. The control method for the dual-drive steam-electric induced draft fan system according to claim 4, characterized in that, The generated energy from the asynchronous motor / generator is stored in the second energy storage device via the plant power bus and energy storage converter.

6. A steam-electric dual-drive induced draft fan system, characterized in that, The system includes: a steam turbine, an asynchronous motor / generator, an induced draft fan, a speed-changing clutch, and a unit control system. The steam turbine, the asynchronous electric motor / generator, and the induced draft fan are coaxially connected. The steam turbine selectively engages or disengages from the coaxial shaft system via the speed-changing clutch; The unit control system is communicatively connected to the steam turbine, the asynchronous electric motor / generator, the induced draft fan, and the variable speed clutch, respectively. The unit control system is used to execute the control method of the steam-electric dual-drive induced draft fan system according to any one of claims 1-5.

7. The steam-electric dual-drive induced draft fan system according to claim 6, characterized in that, The system also includes: a thermal power unit, a hybrid energy storage control system, and a first energy storage device, wherein... The hybrid energy storage control system is communicatively connected to the unit control system; The hybrid energy storage control system is also connected to the thermal power unit and the first energy storage device respectively; The hybrid energy storage control system is used to store a preset proportion of the power generation of the thermal power unit in the first energy storage device when it receives the load reduction instruction from the dispatch AGC and performs deep peak shaving.

8. The steam-electric dual-drive induced draft fan system according to claim 7, characterized in that, The system also includes: a plant power busbar, an energy storage converter, and a second energy storage device, wherein... The AC side of the energy storage converter is connected to the plant power bus, and the DC side of the energy storage converter is connected to the second energy storage device. The asynchronous motor / generator is connected to the plant power bus.

9. The steam-electric dual-drive induced draft fan system according to claim 8, characterized in that, The system also includes a circuit breaker connected between the asynchronous motor / generator and the plant power bus.

10. The steam-electric dual-drive induced draft fan system according to claim 8, characterized in that, The first energy storage device is a lithium iron phosphate battery energy storage device; The second energy storage device is a lithium titanate battery power type energy storage device.

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