A method of controlling the temperature of a gas turbine turbine cooler

Abstract

The embodiment of the application provides a kind of gas turbine turbine cooler temperature control method, comprising: when the load of engine is less than 120WM after starting, third pneumatic regulating valve keeps closed state;Second pneumatic regulating valve adopts PID closed loop regulation mode and automatically adjusts the outlet cooling air temperature of TCA cooler;When the load of engine increases to 120WM, third pneumatic regulating valve gradually opens to minimum opening degree according to preset first rate, and is automatically put into after preset delay;When third pneumatic regulating valve opens to minimum opening degree, second pneumatic regulating valve gradually closes according to preset second rate, until full close;When accident occurs, the actual value of the outlet cooling air temperature of TCA cooler is greater than preset temperature difference than set value, cut off third pneumatic regulating valve automatically, and keep the current opening degree of third pneumatic regulating valve;While fast open second pneumatic regulating valve to 60%, and is automatically put into after preset delay.The application can guarantee the flow demand of TCA cooler under the operating condition of engine, and improve the safety of unit.

Description

Technical Field

[0001] This invention relates to the field of gas turbine technology, and more specifically, to a method for controlling the temperature of a gas turbine cooler. Background Technology

[0002] A gas turbine is an internal combustion engine that uses a continuously flowing gas as its working fluid to drive a high-speed rotating impeller, converting the energy of fuel into useful work. It is a type of rotary turbine thermal engine. The turbine cooling air system (TCA) is used to cool the turbine rotor and blades. The cooling air comes from the compressor exhaust, is cooled by the TCA, and then supplied to the turbine rotor and blades. The cooling water for the TCA comes from a high-pressure feedwater pump. Because the cooling effect of the TCA system directly affects the safe operation of the gas turbine and its output, it plays a crucial role.

[0003] Currently, most gas turbine cooler temperature control methods are centered on flow control, indirectly controlling the cooler's outlet temperature. During normal gas turbine operation, the cooling water flow rate of the turbine cooler is controlled by two return water valves. One return water goes to the condenser, while the other mixes with the high-pressure economizer outlet water before returning to the high-pressure steam drum. These two return water lines are switched. When switching to the return water path that mixes with the high-pressure economizer outlet water before returning to the high-pressure steam drum, this return water valve operates in open-loop control. The valve's CV value is calculated based on the set flow rate and the pressure difference before and after the valve, and the valve opening is then calculated based on a preset CV curve in the logic. Therefore, when the actual CV curve of the valve changes, the calculated opening will deviate significantly from the set flow rate value, failing to meet the flow requirements of the turbine cooler under the current operating conditions. In severe cases, this could even threaten the unit's safety. Furthermore, in the existing technology, the TCA return water mixes with the high-pressure economizer outlet water and then flows into the high-pressure steam drum. The high-pressure economizer feedwater pipeline and the TCA feedwater pipeline interfere with each other and are difficult to control. Summary of the Invention

[0004] This specification provides a method for controlling the temperature of a gas turbine cooler to overcome at least one technical problem existing in the prior art.

[0005] According to the embodiments of this specification, a method for controlling the temperature of a gas turbine cooler is provided. The method for controlling the temperature of a gas turbine cooler is applied to a gas turbine cooling system. The gas turbine cooling system includes a high-pressure feedwater pump, a first flow meter, a second flow meter, a first pneumatic regulating valve, a second pneumatic regulating valve, a third pneumatic regulating valve, an inlet water regulating valve, a TCA cooler, a high-pressure steam drum, a high-pressure economizer, a temperature measuring device, and a PID controller.

[0006] The outlet of the high-pressure feedwater pump has two leads, one to the inlet of the high-pressure economizer and the other to the inlet of the TCA cooler. A first flow meter and a water inlet valve are sequentially installed between the high-pressure feedwater pump and the high-pressure economizer along the water flow direction. The outlet of the high-pressure economizer is connected to the high-pressure steam drum. A second flow meter and a first pneumatic regulating valve are sequentially installed between the high-pressure feedwater pump and the TCA cooler along the water flow direction. The outlet of the TCA cooler has two leads, one to the high-pressure steam drum and the other to the condenser. A second pneumatic regulating valve is installed between the TCA cooler and the condenser. A third pneumatic regulating valve is installed between the TCA cooler and the high-pressure steam drum. A temperature measuring device is installed at the outlet of the TCA cooler to monitor the outlet cooling air temperature. The input of the PID controller is electrically connected to the temperature measuring device. The output of the PID controller is electrically connected to the second and third pneumatic regulating valves.

[0007] The method for controlling the temperature of the gas turbine cooler includes:

[0008] The temperature measuring device monitors the outlet cooling air temperature of the TCA cooler in real time.

[0009] When the load is less than 120 MW after the gas turbine starts, the third pneumatic regulating valve remains closed; the second pneumatic regulating valve automatically adjusts the outlet cooling air temperature of the TCA cooler using the PID controller in a PID closed-loop regulation mode.

[0010] When the gas turbine load increases to 120 MW, the third pneumatic regulating valve gradually opens to the minimum opening at a preset first rate, and after a preset first delay time, the outlet cooling air temperature of the TCA cooler is automatically adjusted by the PID controller using PID closed-loop regulation. When the third pneumatic regulating valve opens to the minimum opening, the second pneumatic regulating valve gradually closes at a preset second rate until it is fully closed.

[0011] When an accident occurs and the actual value of the outlet cooling air temperature of the TCA cooler is greater than the set value by a preset temperature difference, the automatic adjustment of the third pneumatic regulating valve is cut off, and the current opening of the third pneumatic regulating valve is maintained; at the same time, the second pneumatic regulating valve is quickly opened to 60%, and after a preset second delay time, the second pneumatic regulating valve automatically adjusts the outlet cooling air temperature of the TCA cooler using the PID controller in a PID closed-loop regulation mode.

[0012] Preferably, the PID closed-loop control method specifically includes:

[0013] The PID controller receives the actual value of the outlet cooling air temperature sent by the temperature measuring device;

[0014] The PID controller periodically samples the actual temperature of the outlet cooling air and periodically calculates the average value of the actual temperature.

[0015] The actual average temperature is compared with the set value, and the comparison result is obtained;

[0016] The PID controller performs calculations based on the comparison results to obtain the calculation result;

[0017] Based on the calculation results, the PID controller adjusts the opening degree of the second pneumatic regulating valve or the third pneumatic regulating valve.

[0018] More preferably, the sampling period of the periodic sampling is 5 seconds, and the period for calculating the average actual temperature is 25 seconds, 30 seconds, or 35 seconds.

[0019] More preferably, the PID controller includes a comparator; the comparator compares the actual average temperature with the set value and obtains the comparison result.

[0020] Preferably, the preset temperature difference is 40°C; and the minimum opening of the third pneumatic regulating valve is 45%.

[0021] Preferably, the preset first rate is the same as the preset second rate.

[0022] Preferably, both the first delay time and the second delay time are 5 seconds.

[0023] Preferably, the gas turbine cooling system further includes a first differential pressure transmitter and a second differential pressure transmitter; the first differential pressure transmitter is connected in parallel with the water inlet valve; and the second differential pressure transmitter is connected in parallel with the third pneumatic regulating valve.

[0024] Preferably, the temperature measuring device is an air temperature measuring instrument.

[0025] Preferably, the water supply valve is an electrically controlled valve.

[0026] By applying the embodiments in this specification, the pneumatic regulating valve for the TCA cooler returning to the high-pressure steam drum is designed not to track the cooling water flow rate, but instead to track the outlet cooling air temperature of the TCA cooler. The valve opening is calculated based on a comparison between the set value and the actual value of the outlet cooling air temperature of the TCA cooler, and is adjusted in real time accordingly. This achieves direct control of the TCA cooler outlet temperature, solving the problem in existing technologies where indirect control of the outlet temperature via flow control results in a large deviation between the calculated valve opening and the set flow rate value due to changes in the actual CV curve of the valve. This ensures the flow rate requirement of the TCA cooler under gas turbine operating conditions, improving unit safety. Simultaneously, the TCA cooler return water is directly introduced into the high-pressure steam drum, and the high-pressure economizer feedwater pipeline and the TCA cooler feedwater pipeline are completely opposite, without interference, making control easier and more practical.

[0027] The innovative aspects of the embodiments in this specification include:

[0028] 1. In this embodiment, the control object of the TCA cooler is changed from the feed water flow rate to the outlet cooling air temperature, and the outlet temperature is directly controlled. This enables a wide range of adjustment of the TCA cooler outlet temperature and effectively solves the problem of large flow rate deviation during the open-loop control of cooling water flow rate.

[0029] 2. In this embodiment, the pneumatic regulating valve for the TCA cooler returning to the high-pressure steam drum is gradually closed only when it is opened to the minimum opening degree of 45%. This minimizes the occurrence of low supply flow to the TCA cooler during the switching process and improves the safety of the unit.

[0030] 3. In this embodiment, limiting the minimum opening of the pneumatic regulating valve for the TCA cooler returning to the high-pressure steam drum can prevent the TCA cooler from experiencing low supply flow due to over-adjustment by the PID controller, thus preventing the pneumatic regulating valve for the TCA cooler returning to the condenser from frequently opening rapidly and improving the service life of the equipment.

[0031] 4. In this embodiment, during an accident, the automatic control of the pneumatic regulating valve for the TCA cooler returning to the high-pressure steam drum is cut off and the current opening is maintained. At the same time, the pneumatic regulating valve for the TCA cooler returning to the condenser is quickly opened. The flow rate of the TCA cooler is adjusted by using the pneumatic regulating valve for returning to the condenser. This prevents the two regulating valves from adjusting at the same time, which would cause unnecessary mutual disturbance. This makes the control easier and more precise.

[0032] 5. In this embodiment, the return water from the TCA cooler is directly introduced into the high-pressure steam drum, so that the feed water pipeline of the high-pressure economizer and the feed water pipeline of the TCA cooler are completely opposite to each other and do not interfere with each other, making it easier to control. Attached Figure Description

[0033] To more clearly illustrate the technical solutions in the embodiments or prior art of this specification, the drawings used in the description of the embodiments or prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0034] Figure 1 A schematic diagram of the gas turbine cooling system used in the gas turbine cooler temperature control method provided in the embodiments of this specification;

[0035] Figure 2 A structural block diagram of the gas turbine cooling system used in the gas turbine cooler temperature control method provided in the embodiments of this specification;

[0036] Explanation of reference numerals in the attached drawings: 1 is the high-pressure feed water pump, 2 is the first flow meter, 3 is the second flow meter, 4 is the first pneumatic regulating valve, 5 is the second pneumatic regulating valve, 6 is the third pneumatic regulating valve, 7 is the water supply regulating valve, 8 is the TCA cooler, 9 is the high-pressure steam drum, 10 is the high-pressure economizer, 11 is the temperature measuring device, 12 is the PID controller, 13 is the comparator, 14 is the first differential pressure transmitter, and 15 is the second differential pressure transmitter. Detailed Implementation

[0037] The technical solutions in the embodiments of this specification will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0038] It should be noted that the terms "comprising" and "having," and any variations thereof, in the embodiments and drawings of this specification are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or devices.

[0039] This specification discloses a method for controlling the temperature of a gas turbine cooler. The following are detailed descriptions of each method.

[0040] This method for controlling the temperature of a gas turbine cooler is applied to a gas turbine cooling system. Figure 1 , Figure 2 This illustrates a gas turbine cooling system provided according to an embodiment of this description. For example... Figure 1 and Figure 2 As shown, the gas turbine cooling system includes a high-pressure feedwater pump 1, a first flow meter 2, a second flow meter 3, a first pneumatic regulating valve 4, a second pneumatic regulating valve 5, a third pneumatic regulating valve 6, a water inlet valve 7, a TCA cooler 8, a high-pressure steam drum 9, a high-pressure economizer 10, a temperature measuring device 11, a PID controller 12, a first differential pressure transmitter 14, and a second differential pressure transmitter 15.

[0041] The outlet of the high-pressure feedwater pump 1 is connected to two separate outlets: one to the inlet of the high-pressure economizer 10 and the other to the inlet of the TCA cooler 8. This allows the water pumped by the high-pressure feedwater pump 1 to supply water to both the high-pressure economizer 10 and the TCA cooler 8. A first flow meter 2 and a water inlet valve 7 are sequentially installed between the high-pressure feedwater pump 1 and the high-pressure economizer 10 along the water flow direction. The first flow meter 2 detects the water inlet flow of the high-pressure economizer 10, and the water inlet valve 7 regulates the water flow from the high-pressure feedwater pump 1 to the high-pressure economizer 10. A first differential pressure transmitter 14 is connected in parallel with the water inlet valve 7. The first differential pressure transmitter 14 detects the pressure difference before and after the water inlet valve 7, which is an electrically controlled valve. The outlet of the high-pressure economizer 10 is connected to the high-pressure steam drum 9, and the water from the high-pressure economizer 10 is supplied to the high-pressure steam drum 9.

[0042] A second flow meter 3 and a first pneumatic regulating valve 4 are sequentially installed between the high-pressure feedwater pump 1 and the TCA cooler 8 along the water flow direction. The second flow meter 3 detects the inlet water flow of the TCA cooler 8, and the first pneumatic regulating valve 4 regulates the flow rate of the high-pressure feedwater pump 1 to the TCA cooler 8. Two outlets of the TCA cooler 8 are led to the high-pressure steam drum 9 and the condenser (not shown in the figure), respectively. A second pneumatic regulating valve 5 is installed between the TCA cooler 8 and the condenser to regulate the water flow rate back to the condenser from the TCA cooler 8. A third pneumatic regulating valve 6 is installed between the TCA cooler 8 and the high-pressure steam drum 9 to regulate the water flow rate back to the high-pressure steam drum 9 from the TCA cooler 8. A second differential pressure transmitter 15 is connected in parallel with the third pneumatic regulating valve 6, and the second differential pressure transmitter 15 detects the pressure difference before and after the third pneumatic regulating valve 6. A temperature measuring device 11 is installed at the outlet of the TCA cooler 8 to monitor the outlet cooling air temperature of the TCA cooler 8; the temperature measuring device 11 is preferably an air temperature measuring instrument. The input terminal of the PID controller 12 is electrically connected to the temperature measuring device 11. The actual value of the cooling air temperature at the outlet of the TCA cooler 8 detected by the temperature measuring device 11 is sent to the PID controller 12. After calculation in the PID controller 12, the calculation result is obtained. The output terminal of the PID controller 12 is electrically connected to the second pneumatic regulating valve 5 and the third pneumatic regulating valve 6 respectively. The PID controller 12 adjusts the opening degree of the second pneumatic regulating valve 5 or the third pneumatic regulating valve 6 according to the obtained calculation result, thereby directly controlling the cooling air temperature at the outlet of the TCA cooler 8.

[0043] In the embodiments described in this specification, the gas turbine cooling system uses a temperature measuring device 11 to directly monitor the outlet cooling air temperature of the TCA cooler 8, and thereby controls the cooling water flow rate of the TCA cooler 8, thus achieving direct control of the outlet cooling air temperature of the TCA cooler 8. Simultaneously, instead of mixing the return water from the TCA cooler 8 with the outlet water from the high-pressure economizer 10 before being fed into the high-pressure steam drum 9, the existing technology has been modified so that the return water from the TCA cooler 8 and the outlet water from the high-pressure economizer 10 flow directly into the high-pressure steam drum 9, making the feedwater pipelines of the high-pressure economizer 10 and the TCA cooler 8 independent and non-interfering, thus facilitating control.

[0044] The gas turbine cooler temperature control method provided in the embodiments of this specification includes:

[0045] The temperature measuring device monitors the outlet cooling air temperature of the TCA cooler in real time.

[0046] A temperature measuring device is used to detect the actual value of the outlet cooling air temperature of the TCA cooler in real time, and the detected actual value of the outlet cooling air temperature is sent to the PID controller. This allows the outlet temperature of the TCA cooler to be adjusted in real time based on the actual value of the outlet cooling air temperature. This changes the control object of the TCA cooler from the feed water flow rate to the outlet cooling air temperature, allowing direct control of the outlet temperature. This enables wide-range adjustment of the TCA cooler outlet temperature and effectively solves the problem of large flow rate deviation in the open-loop control of cooling water flow rate.

[0047] When the load is less than 120MW after the gas turbine starts, the third pneumatic regulating valve remains closed; the second pneumatic regulating valve uses a PID controller to automatically adjust the outlet cooling air temperature of the TCA cooler using a PID closed-loop regulation method.

[0048] It should be noted and understood that the third pneumatic regulating valve in the embodiments of this specification is the pneumatic regulating valve for the TCA cooler returning to the high-pressure steam drum, and the second pneumatic regulating valve is the pneumatic regulating valve for the TCA cooler returning to the condenser.

[0049] The pneumatic regulating valve for the TCA cooler returning to the high-pressure steam drum is PID-controlled in a closed loop based on the outlet cooling air temperature of the TCA cooler. The pneumatic regulating valves for the TCA cooler returning to the high-pressure steam drum and returning to the condenser switch according to the gas turbine load. When the gas turbine starts and its load is less than 120 MW, the pneumatic regulating valve for the TCA cooler returning to the condenser (the second pneumatic regulating valve) automatically adjusts the TCA cooler outlet temperature. The pneumatic regulating valve for the TCA cooler returning to the high-pressure steam drum (the third pneumatic regulating valve) remains closed until the gas turbine load reaches 120 MW.

[0050] In a specific embodiment, the second pneumatic regulating valve can automatically adjust the outlet cooling air temperature of the TCA cooler using a PID controller with PID closed-loop regulation.

[0051] More specifically, the PID controller receives the actual value of the outlet cooling air temperature sent by the temperature measuring device; the PID controller periodically samples the actual value of the outlet cooling air temperature and periodically calculates the average value of the actual temperature; the average value of the actual temperature is compared with the set value, and the comparison result is obtained; the PID controller performs calculations based on the comparison result and obtains the calculation result; based on the calculation result, the PID controller adjusts the opening of the second pneumatic regulating valve.

[0052] In a specific implementation, the sampling period for periodic sampling is 5 seconds, and the period for calculating the average actual temperature is 25 seconds, 30 seconds, or 35 seconds. Furthermore, the PID controller includes a comparator, which compares the average actual temperature with the set value to obtain a comparison result. The outlet cooling air temperature of the TCA cooler is sampled every 5 seconds, and the average value is calculated every 25, 30, or 35 seconds to obtain the actual value of the outlet cooling air temperature of the TCA cooler. Then, the comparator compares the actual value of the outlet cooling air temperature of the TCA cooler with the set value of the outlet cooling air temperature of the TCA cooler set by the system to obtain a comparison result. The comparison result is calculated in the PID controller to obtain the calculation result. Specifically, in the embodiments of this specification, the comparison result can be proportional to the calculation result. The PID controller outputs the calculation result based on the comparison result and adjusts the opening of the TCA cooler return condenser pneumatic regulating valve according to the calculation result. By controlling the opening of the return condenser pneumatic regulating valve, the outlet temperature of the TCA cooler is controlled, keeping the outlet temperature of the TCA cooler near the set value.

[0053] When the gas turbine load increases to 120 MW, the third pneumatic regulating valve gradually opens to the minimum opening at a preset first rate, and after a preset first delay time, the outlet cooling air temperature of the TCA cooler is automatically adjusted by the PID controller using PID closed-loop regulation. When the third pneumatic regulating valve opens to the minimum opening, the second pneumatic regulating valve gradually closes at a preset second rate until it is fully closed.

[0054] Specifically, the preset first speed is the same as the preset second speed; the first delay time is preferably 5 seconds; and the minimum opening of the third pneumatic regulating valve is 45%.

[0055] In a specific embodiment, when the gas turbine load increases to over 120 MW, the pneumatic regulating valve returning the TCA cooler to the high-pressure steam drum gradually opens to 45% at a preset first rate; that is, the third pneumatic regulating valve opens to its minimum opening at a certain rate, and then engages automatic operation after 5 seconds. Simultaneously, after the third pneumatic regulating valve opens to 45%, the pneumatic regulating valve returning the TCA cooler to the condenser gradually closes at a preset second rate until it is fully closed. Furthermore, as the gas turbine load increases, the second pneumatic regulating valve (the one returning the TCA cooler to the condenser) remains in a standby closed state.

[0056] The gas turbine cooler temperature control method described in this specification limits the minimum opening of the pneumatic regulating valve for the TCA cooler returning to the high-pressure steam drum. It is set so that the pneumatic regulating valve for the TCA cooler returning to the high-pressure steam drum is only gradually closed when the valve reaches its minimum opening of 45%. On the one hand, this minimizes the occurrence of low TCA cooler supply flow during switching, improving unit safety. On the other hand, it prevents frequent rapid opening of the pneumatic regulating valve for the TCA cooler returning to the condenser due to low TCA cooler supply flow caused by over-adjustment of the PID controller, thus extending equipment lifespan.

[0057] In a specific embodiment, the third pneumatic regulating valve automatically adjusts the outlet cooling air temperature of the TCA cooler using a PID controller with closed-loop PID control. The PID controller receives the actual outlet cooling air temperature value from the temperature measuring device, periodically samples this value, and periodically calculates the average temperature. Then, it compares the average temperature value with a set value to obtain a comparison result. Based on the comparison result, the PID controller performs calculations to obtain a result, and adjusts the opening of the third pneumatic regulating valve accordingly.

[0058] In a specific implementation process, the outlet cooling air temperature of the TCA cooler is sampled every 5 seconds, and the average value is calculated every 25, 30, or 35 seconds to obtain the actual outlet cooling air temperature of the TCA cooler. A comparator is used to compare the actual outlet cooling air temperature of the TCA cooler with the set value to obtain the comparison result. The PID controller performs calculations based on the comparison result, and adjusts the opening of the pneumatic regulating valve returning the TCA cooler to the high-pressure steam drum according to the calculation result, thereby controlling the outlet temperature of the TCA cooler to keep it near the set value. Furthermore, the comparison result and the calculation result can be set as a proportional relationship, so that the calculation result can be obtained based on the comparison result.

[0059] When an accident occurs and the actual value of the outlet cooling air temperature of the TCA cooler is greater than the preset temperature difference value, the automatic adjustment of the third pneumatic regulating valve is cut off, and the current opening of the third pneumatic regulating valve is maintained; at the same time, the second pneumatic regulating valve is quickly opened to 60%, and after a preset second delay time, the second pneumatic regulating valve automatically adjusts the outlet cooling air temperature of the TCA cooler using the PID controller in a PID closed-loop regulation mode.

[0060] Specifically, the preset temperature difference is 40℃; the second delay time is 5 seconds.

[0061] In a specific embodiment, during an accident, if the actual temperature of the cooling air at the outlet of the TCA cooler is greater than the set value by a preset temperature difference, the automatic regulation of the TCA cooler's return-to-high-pressure steam drum pneumatic regulating valve can be cut off, while maintaining the current opening. Simultaneously, the TCA cooler's return-to-condenser pneumatic regulating valve is quickly opened to 60%. After a 5-second delay, the TCA cooler flow rate is automatically regulated by the return-to-condenser pneumatic regulating valve, i.e., the second pneumatic regulating valve, thereby automatically controlling the TCA cooler's outlet cooling air temperature.

[0062] In the embodiments of this specification, during an accident, the pneumatic regulating valve for the TCA cooler returning to the high-pressure steam drum is automatically shut off, while the pneumatic regulating valve for the TCA cooler returning to the condenser is automatically activated. By using the pneumatic regulating valve for the condenser to regulate the flow rate of the TCA cooler, the actual value of the air temperature at the outlet of the TCA cooler can be brought to the set value as quickly as possible. Furthermore, this control method can prevent the two pneumatic regulating valves from being adjusted simultaneously, which would cause unnecessary mutual disturbances and fail to achieve a good control effect.

[0063] The above describes the steps of the gas turbine cooler temperature control method provided in this embodiment, as well as the gas turbine cooling system used. The complete process of the gas turbine cooler temperature control method will be described in detail below.

[0064] In one specific embodiment, the pneumatic regulating valve for the TCA cooler returning to the high-pressure steam drum is PID closed-loop regulated according to the cooling air temperature at the TCA cooler outlet, and the pneumatic regulating valve for the TCA cooler returning to the condenser and returning to the high-pressure steam drum is switched by load.

[0065] When the gas turbine starts and the load is less than 120 MW, the pneumatic regulating valve of the TCA cooler returning to the condenser automatically adjusts the cooling air temperature at the TCA cooler outlet. The pneumatic regulating valve of the TCA cooler returning to the high-pressure steam drum remains closed at -5% until the gas turbine load reaches 120 MW. When the gas turbine load increases to above 120 MW, the pneumatic regulating valve of the TCA cooler returning to the high-pressure steam drum gradually opens at a certain rate to the minimum opening of 45%, and then automatically closes after 5 seconds. When the pneumatic regulating valve of the TCA cooler returning to the high-pressure steam drum reaches its minimum opening, it gradually closes at a certain rate until it is fully closed to -5%. Thereafter, as the gas turbine load increases, the pneumatic regulating valve of the TCA cooler returning to the condenser remains in a standby closed state.

[0066] When an accident occurs, if the actual value of the cooling air temperature at the TCA cooler outlet is greater than a certain value, such as 40°C, the automatic control valve for the TCA cooler returning to the high-pressure steam drum is shut off and maintained in its current position. At the same time, the pneumatic control valve for the TCA cooler returning to the condenser is quickly opened to 60%. After a 5-second delay, the TCA flow rate is automatically adjusted by the pneumatic control valve returning to the condenser to regulate the cooling air temperature at the TCA cooler outlet.

[0067] In summary, this specification discloses a method for controlling the temperature of a gas turbine cooler. The pneumatic regulating valve for the TCA cooler's return to the high-pressure steam drum is redesigned to track the outlet cooling air temperature of the TCA cooler, instead of tracking the cooling water flow rate. The valve opening is calculated based on a comparison between the setpoint and the actual outlet cooling air temperature of the TCA cooler, and adjusted in real time accordingly. This achieves direct control of the TCA cooler's outlet temperature, solving the problem in existing technologies where indirect temperature control via flow rate means a significant deviation between the calculated valve opening and the set flow rate value due to changes in the actual CV curve of the valve. This method ensures the flow rate requirement of the TCA cooler under gas turbine operating conditions, improving unit safety. Furthermore, the TCA cooler return water is directly introduced into the high-pressure steam drum, and the high-pressure economizer feedwater pipeline and the TCA cooler feedwater pipeline are completely separate, preventing interference and facilitating control, thus enhancing practicality.

[0068] Those skilled in the art will understand that the accompanying drawings are merely schematic diagrams of one embodiment, and the modules or processes shown in the drawings are not necessarily essential for implementing the present invention.

[0069] Those skilled in the art will understand that the modules in the apparatus of the embodiments can be distributed in the apparatus of the embodiments as described in the embodiments, or they can be located in one or more devices different from this embodiment with corresponding changes. The modules of the above embodiments can be combined into one module, or they can be further divided into multiple sub-modules.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for controlling the temperature of a gas turbine cooler, characterized in that, The method for controlling the temperature of the gas turbine cooler is applied to a gas turbine cooling system, which includes a high-pressure feedwater pump, a first flow meter, a second flow meter, a first pneumatic regulating valve, a second pneumatic regulating valve, a third pneumatic regulating valve, an inlet water regulating valve, a TCA cooler, a high-pressure steam drum, a high-pressure economizer, a temperature measuring device, and a PID controller. The outlet of the high-pressure feedwater pump has two leads, one to the inlet of the high-pressure economizer and the other to the inlet of the TCA cooler. A first flow meter and a water inlet valve are sequentially installed between the high-pressure feedwater pump and the high-pressure economizer along the water flow direction. The outlet of the high-pressure economizer is connected to the high-pressure steam drum. A second flow meter and a first pneumatic regulating valve are sequentially installed between the high-pressure feedwater pump and the TCA cooler along the water flow direction. The outlet of the TCA cooler has two leads, one to the high-pressure steam drum and the other to the condenser. A second pneumatic regulating valve is installed between the TCA cooler and the condenser. A third pneumatic regulating valve is installed between the TCA cooler and the high-pressure steam drum. A temperature measuring device is installed at the outlet of the TCA cooler to monitor the outlet cooling air temperature. The input of the PID controller is electrically connected to the temperature measuring device. The output terminal of the PID controller is electrically connected to the second pneumatic regulating valve and the third pneumatic regulating valve, respectively. The method for controlling the temperature of the gas turbine cooler includes: The temperature measuring device monitors the outlet cooling air temperature of the TCA cooler in real time. When the gas turbine starting load is less than 120 MW, the third pneumatic regulating valve remains closed; the second pneumatic regulating valve automatically adjusts the outlet cooling air temperature of the TCA cooler using the PID controller in a PID closed-loop regulation mode. When the gas turbine load increases to 120 MW, the third pneumatic regulating valve gradually opens to the minimum opening at a preset first rate, and after a preset first delay time, the outlet cooling air temperature of the TCA cooler is automatically adjusted by the PID controller using PID closed-loop regulation. When the third pneumatic regulating valve opens to the minimum opening, the second pneumatic regulating valve gradually closes at a preset second rate until it is fully closed. When an accident occurs and the actual temperature of the outlet cooling air of the TCA cooler is greater than the set value by a preset temperature difference, the automatic adjustment of the third pneumatic regulating valve is cut off, and the current opening of the third pneumatic regulating valve is maintained. Simultaneously, the second pneumatic regulating valve is quickly opened to 60%. After a preset second delay time, the second pneumatic regulating valve automatically adjusts the outlet cooling air temperature of the TCA cooler using a PID controller with closed-loop regulation. The preset temperature difference is 40°C; the minimum opening of the third pneumatic regulating valve is 45%; and both the first and second delay times are 5 seconds. Specifically, the PID closed-loop control method includes: The PID controller receives the actual value of the outlet cooling air temperature sent by the temperature measuring device; The PID controller periodically samples the actual temperature of the outlet cooling air and periodically calculates the average value of the actual temperature. The actual average temperature is compared with the set value, and the comparison result is obtained; The PID controller performs calculations based on the comparison results to obtain the calculation result; Based on the calculation results, the PID controller adjusts the opening degree of the second pneumatic regulating valve or the third pneumatic regulating valve.

2. The method for controlling the temperature of a gas turbine cooler according to claim 1, characterized in that, The sampling period for the periodic sampling is 5 seconds, and the period for calculating the average actual temperature is 25 seconds, 30 seconds, or 35 seconds.

3. The method for controlling the temperature of a gas turbine cooler according to claim 1, characterized in that, The PID controller includes a comparator; the comparator compares the actual average temperature with the set value and obtains the comparison result.

4. The method for controlling the temperature of a gas turbine cooler according to claim 1, characterized in that, The preset first rate is the same as the preset second rate.

5. The method for controlling the temperature of a gas turbine cooler according to claim 1, characterized in that, The gas turbine cooling system further includes a first differential pressure transmitter and a second differential pressure transmitter; the first differential pressure transmitter is connected in parallel with the water inlet valve; the second differential pressure transmitter is connected in parallel with the third pneumatic regulating valve.

6. The method for controlling the temperature of a gas turbine cooler according to claim 1, characterized in that, The temperature measuring device is an air temperature measuring instrument.

7. The method for controlling the temperature of a gas turbine cooler according to claim 1, characterized in that, The water supply regulating valve is an electrically controlled valve.

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