A method of controlling the temperature of a gas turbine fuel

Abstract

The present application relates to the technical field of gas turbine control, and relates to a kind of gas turbine fuel heating temperature control method, comprising: obtaining the related parameters of gas turbine and fuel heating system;Based on the actual feedwater flow of gas turbine power generation power, preset condenser side fuel heating system set value function and fuel heating system, the opening of adjusting valve FCVC is calculated;Based on the actual fuel heating temperature of fuel heating temperature set value and, the set value of feedwater flow of fuel heating system is calculated, then with the actual feedwater flow of fuel heating system, the opening of adjusting valve FCVH is calculated to form the cascade control of FCVH;Based on the actual feedwater flow of fuel heating system, fuel heating temperature set value, actual fuel heating temperature, fuel flow and the opening of adjusting valve FCVT is calculated, which is calculated based on the outlet temperature of medium-pressure economizer;According to the control of adjusting valve opening in different working conditions, the influence of heating temperature by external interference is reduced by accurately controlling fuel heating temperature.

Description

Technical Field

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

[0002] Under the overall goal, the proportion of installed capacity from new energy sources is increasing year by year. However, power generation methods such as wind and solar power are intermittent and fluctuating, posing challenges to the stability of the power system. Heavy-duty gas turbine power generation has advantages such as rapid start-up and shutdown and fast load response, which can provide support for the stability of the new power system. To improve the efficiency of gas turbine power generation, the fuel is usually heated to increase the enthalpy of the fuel entering the combustion chamber and reduce fuel consumption.

[0003] The structure of the fuel heating system of a gas turbine is as follows: Figure 1 As shown, the heat source comes from the feedwater at the outlet of the medium-pressure economizer. After heating the fuel in the fuel heater, the feedwater can return to the condenser or the low-pressure economizer of the waste heat boiler. The feedwater flow rate returning to the condenser is regulated by the condenser-side flow control valve (FCVC), and the feedwater flow rate returning to the waste heat boiler is regulated by the waste heat boiler-side flow control valve (FCVH). Both FCVC and FCVH can regulate the feedwater flow rate through the fuel heater. The supplied fuel is regulated by the three-way flow control valve (FCVT) to control the fuel flow rate entering the fuel heater and the fuel flow rate bypassing the fuel heater. The two fuel streams merge and enter the combustion chamber for combustion. FCVC and FCVH regulate the feedwater flow rate of the fuel heating system to control the fuel heating temperature (i.e., the fuel temperature entering the combustion chamber), and FCVT regulates the proportion of fuel being heated to regulate the fuel heating temperature. FCVC, FCVH, and FCVT coordinate with each other to achieve fuel heating temperature control.

[0004] In current fuel heating temperature control methods, FCVC employs closed-loop control. The setpoint for the condenser-side fuel heating system feedwater flow rate is calculated from the gas turbine's power generation, and the difference between this setpoint and the actual feedwater flow rate is used to calculate the FCVC opening degree via a PID controller. FCVH employs open-loop control, directly calculating the FCVH opening degree from the gas turbine's power generation. FCVT employs closed-loop control, calculating the FCVT opening degree by comparing the fuel heating temperature setpoint with the actual fuel heating temperature using a PID controller. When the gas turbine's power generation is low, the FCVC controls the feedwater flow rate of the fuel heating system, while FCVH remains fully closed, and all feedwater from the fuel heating system returns to the condenser. When the gas turbine's power generation is high, FCVH opens, and FCVC gradually closes. The FCVH controls the feedwater flow rate of the fuel heating system, directing the feedwater into the low-pressure economizer of the waste heat boiler.

[0005] Current fuel heating temperature control logic directly calculates the FCVH opening based on the gas turbine's power output when the turbine's power generation is high. However, this only provides a rough control of the fuel heating system's feedwater flow rate, and changes in the feedwater flow rate directly affect the fuel heating temperature. Furthermore, the FCVT uses a single-loop closed-loop control for fuel heating temperature. Changes in the feedwater flow rate, the intermediate-pressure economizer outlet temperature, and the fuel flow rate will cause changes in the fuel heating temperature. The FCVT only activates to maintain the fuel heating temperature at the setpoint after these changes, resulting in poor anti-interference capabilities. Summary of the Invention

[0006] In view of this, in order to solve the problems of poor anti-interference ability and poor accuracy of fuel heating temperature control in existing fuel heating temperature control logic, the present invention provides a gas turbine fuel heating temperature control method, which can achieve precise control of fuel heating temperature and reduce the impact of external interference on fuel heating temperature.

[0007] This invention provides a method for controlling the fuel heating temperature of a gas turbine, comprising:

[0008] Obtain the gas turbine power generation P, the actual feedwater flow rate F of the fuel heating system, and the fuel heating temperature setpoint T. Foutsv Actual fuel heating temperature T Fout Fuel flow rate F F Medium-pressure economizer outlet temperature T IE ;

[0009] Based on the gas turbine power generation P, the preset setpoint function of the feedwater flow rate of the condenser-side fuel heating system, and the actual feedwater flow rate F of the fuel heating system, the opening degree of the condenser-side flow regulating valve FCVC is calculated.

[0010] Based on fuel heating temperature setpoint T Foutsv Compared with the actual fuel heating temperature T Fout Calculate the feedwater flow setpoint F for the waste heat boiler side fuel heating system. SVH Then, the opening degree of the regulating valve FCVH is calculated based on the actual water flow rate F of the fuel heating system, thus forming a cascade control of FCVH;

[0011] Based on the actual water supply flow rate F of the fuel heating system and the fuel heating temperature setpoint T Foutsv Actual fuel heating temperature T Fout Fuel flow rate F F and the outlet temperature T of the medium-pressure economizer IE Calculate the opening degree of the three-way flow control valve FCVT;

[0012] The opening degree of the condenser-side flow regulating valve FCVC, the waste heat boiler-side flow regulating valve FCVH, and the three-way flow regulating valve FCVT is controlled according to different operating conditions to control the fuel heating temperature of the gas turbine.

[0013] This invention achieves precise control of fuel heating temperature by acquiring monitoring data from the gas turbine and fuel heating system, using a multi-PID controller to adjust the opening of FCVH and FCVC to control the feedwater flow of the fuel heating system, and adjusting the opening of the three-way valve FCVT, thereby reducing the impact of external interference on the fuel heating temperature.

[0014] In one optional implementation, calculating the opening degree of the condenser-side flow regulating valve FCVC based on the gas turbine power generation P, a preset setpoint function for the feedwater flow rate of the condenser-side fuel heating system, and the actual feedwater flow rate F of the fuel heating system includes:

[0015] Based on the gas turbine power generation P and the preset setpoint function for the feedwater flow rate of the condenser-side fuel heating system, the setpoint value F for the feedwater flow rate of the condenser-side fuel heating system is obtained. SVC ;

[0016] Set the feedwater flow rate F of the condenser-side fuel heating system SVC The difference between the actual feedwater flow rate F of the fuel heating system and the input to the first PID controller yields the opening command U of the condenser-side flow control valve FCVC. C .

[0017] In this embodiment of the invention, the feedwater flow rate of the fuel heating system is adjusted to the desired value by adjusting the opening degree of the FCVC.

[0018] In one alternative implementation, the fuel heating temperature setpoint T is... Foutsv Compared with the actual fuel heating temperature T FoutCalculate the feedwater flow setpoint F for the waste heat boiler side fuel heating system. SVH Then, the opening degree of the regulating valve FCVH is calculated based on the actual feedwater flow rate F of the fuel heating system, forming a cascade control of FCVH, including:

[0019] Obtain the return water temperature T of the fuel heating system WB ;

[0020] When the gas turbine power generation P is higher than the preset high limit threshold and the fuel heating system return water temperature T WB When the temperature is below the preset lower threshold, the fuel heating temperature setpoint T will be adjusted. Foutsv Compared with the actual fuel heating temperature T Fout The deviation is input to the second PID controller;

[0021] The output of the second PID controller is compared with the setpoint F of the feedwater flow rate of the condenser-side fuel heating system. SVC The larger value is taken as the setpoint F for the feedwater flow rate of the waste heat boiler side fuel heating system. SVH ;

[0022] The third PID controller is based on the set value F of the feedwater flow rate of the fuel heating system on the waste heat boiler side. SVH The opening degree of the waste heat boiler-side flow regulating valve FCVH is calculated based on the actual feedwater flow rate F of the fuel heating system, and the opening degree command U of the waste heat boiler-side flow regulating valve FCVH is output. H This forms a cascade control over the fuel heating temperature.

[0023] In an optional implementation, the method further includes: when the gas turbine power generation P is less than a preset upper limit threshold or the fuel heating system return water temperature T... WB When the flow rate exceeds the preset lower threshold, the second PID controller output tracks the actual feedwater flow rate F of the fuel heating system, and the third PID controller output tracks the flow rate U calculated from the gas turbine power generation P and the preset functional relationship between the gas turbine power generation and FCVH opening. H0 and U H0 As the opening command U of the FCVH flow regulating valve on the waste heat boiler side. H The cascade control was cancelled, and the opening degree of the waste heat boiler side flow regulating valve FCVH was controlled by an open loop.

[0024] In an optional implementation, it further includes: when the feedwater flow rate setpoint F of the waste heat boiler side fuel heating system is... SVH When the deviation from the actual water supply flow rate F of the fuel heating system exceeds a preset threshold, the second PID controller outputs a value that tracks the actual water supply flow rate F of the fuel heating system, and the third PID controller outputs a value that tracks the actual water supply flow rate U. H0 and U H0 As the opening command U of the FCVH flow regulating valve on the waste heat boiler side.H When both the second and third PID controllers are in tracking mode, the setpoint F for the feedwater flow rate of the waste heat boiler side fuel heating system is... SVH The actual water flow rate F of the fuel heating system is equal to that of the fuel heating system. After a preset delay time, the second and third PID controllers cancel tracking and resume cascade control.

[0025] In an optional implementation, the method further includes: setting an enable signal, wherein when the enable signal is activated, the second PID controller and the third PID controller are always in a tracking state, and the output of the third PID controller tracks U. H0 and U H0 The final FCVH opening command U is used as the flow control valve on the waste heat boiler side. H .

[0026] This invention provides a double-insurance setting by setting an enable signal, ensuring that the FCVH opening can still be controlled even if the FCVH opening control logic provided by this invention fails.

[0027] In one optional implementation, the actual feedwater flow rate F of the fuel heating system and the fuel heating temperature setpoint T are used. Foutsv Actual fuel heating temperature T Fout Fuel flow rate F F and the outlet temperature T of the medium-pressure economizer IE Calculate the opening degree of the three-way flow control valve FCVT, including:

[0028] fuel heating temperature setpoint T Foutsv Compared with the actual fuel heating temperature T Fout The difference is input to the fourth PID controller;

[0029] Obtain the actual feedwater flow rate F and fuel flow rate F of the fuel heating system F and the outlet temperature T of the medium-pressure economizer IE Each has its corresponding feedforward coefficient, and the feedforward control quantity of the three is obtained based on their respective feedforward coefficients;

[0030] By combining the feedforward control values ​​of the three controllers with the output of the fourth PID controller, the opening command U of the three-way flow control valve FCVT is obtained. T .

[0031] In one optional embodiment, the actual water flow rate F and fuel flow rate F of the fuel heating system are... F and the outlet temperature T of the medium-pressure economizer IE The corresponding feedforward coefficients are determined based on on-site debugging.

[0032] In this embodiment of the invention, feedforwards of fuel flow rate, medium-pressure economizer outlet temperature, and fuel heating system feedwater flow rate are introduced into the traditional FCVT control process. When operating conditions change, the opening degree of the FCVT is adjusted before changes in fuel flow rate, medium-pressure economizer outlet temperature, and fuel heating system feedwater flow rate cause changes in fuel heating temperature, thereby reducing the impact of external disturbances on fuel heating temperature. Attached Figure Description

[0033] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in 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 the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0034] Figure 1 This is a schematic diagram of the structure of the fuel heating system for a gas turbine provided in an embodiment of the present invention;

[0035] Figure 2 This is a schematic flowchart of the gas turbine fuel heating temperature control method provided in an embodiment of the present invention;

[0036] Figure 3 This is a schematic diagram of the feedwater flow rate setpoint function of the condenser-side fuel heating system provided in an embodiment of the present invention;

[0037] Figure 4 This is a schematic diagram of the correspondence function between gas turbine power generation and FCVH opening provided in an embodiment of the present invention;

[0038] Figure 5 This is a schematic diagram of the FCVC opening degree control logic structure provided in an embodiment of the present invention;

[0039] Figure 6 This is a schematic diagram of the FCVH opening degree control logic structure provided in an embodiment of the present invention;

[0040] Figure 7 This is a schematic diagram of the FCVT opening control logic structure provided in an embodiment of the present invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention 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, 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.

[0042] This embodiment provides a method for controlling the fuel heating temperature of a gas turbine. Figure 2 This is a flowchart of a gas turbine fuel heating temperature control method according to an embodiment of the present invention, such as... Figure 2 As shown, the process includes the following steps:

[0043] Step S101: Obtain the gas turbine power generation P, the actual feedwater flow rate F of the fuel heating system, and the fuel heating temperature setpoint T. Foutsv Actual fuel heating temperature T Fout Fuel flow rate F F Medium-pressure economizer outlet temperature T IE .

[0044] This invention acquires monitoring data of the gas turbine and fuel heating system during operation, understands the actual operating conditions based on the monitoring data, and then adjusts the opening of FCVH and FCVC under different operating conditions to control the feedwater flow of the fuel heating system, and adjusts the opening of the three-way valve FCVT to control the proportion of fuel being heated, thereby achieving precise control of the fuel heating temperature and reducing the impact of external interference on the fuel heating temperature.

[0045] Step S102: Calculate the opening degree of the condenser-side flow regulating valve FCVC based on the gas turbine power generation P, the preset setpoint function of the feedwater flow rate of the condenser-side fuel heating system, and the actual feedwater flow rate F of the fuel heating system.

[0046] Specifically, in this embodiment of the invention, based on the gas turbine power generation P and the preset setpoint function for the feedwater flow rate of the condenser-side fuel heating system (the preset setpoint function for the feedwater flow rate of the condenser-side fuel heating system is as follows...), Figure 3 As shown), obtain the setpoint F of the feedwater flow rate of the condenser-side fuel heating system. SVC And set the feedwater flow rate F of the condenser-side fuel heating system. SVC The difference between the actual feedwater flow rate F of the fuel heating system and the input to the first PID controller yields the opening command U of the condenser feedwater flow regulating valve FCVC. C By adjusting the opening of the FCVC, the feedwater flow rate of the fuel heating system can be made to reach the desired value.

[0047] Step S103, based on the fuel heating temperature setpoint T Foutsv Compared with the actual fuel heating temperature T Fout Calculate the feedwater flow setpoint F for the waste heat boiler side fuel heating system. SVH Then, the opening degree of the regulating valve FCVH is calculated based on the actual water flow rate F of the fuel heating system, thus forming a cascade control of FCVH.

[0048] Specifically, in this embodiment of the invention, the return water temperature T of the fuel heating system is obtained. WB When the gas turbine power generation P is higher than the preset high limit threshold and the fuel heating system return water temperature T WB When the temperature is below the preset lower threshold, the fuel heating temperature setpoint T will be adjusted. Foutsv Compared with the actual fuel heating temperature T Fout The deviation is input to the second PID controller; the output of the second PID controller is compared with the setpoint F of the feedwater flow rate of the condenser-side fuel heating system. SVC The larger value is taken as the setpoint F for the feedwater flow rate of the waste heat boiler side fuel heating system. SVH The third PID controller is based on the setpoint F of the feedwater flow rate of the fuel heating system on the waste heat boiler side. SVH The opening degree of the waste heat boiler-side flow regulating valve FCVH is calculated based on the actual feedwater flow rate F of the fuel heating system, and the opening degree command U of the waste heat boiler-side flow regulating valve FCVH is output. H This forms a cascade control over the fuel heating temperature.

[0049] When the gas turbine power generation P exceeds the preset high limit threshold (e.g., above 125MW) and the fuel heating system return water temperature T WB When the temperature is below a preset lower threshold (e.g., below 140°C), the fuel heating temperature setpoint T will be adjusted. Foutsv Compared with the actual fuel heating temperature T Fout The deviation is input to the second PID controller; the output of the second PID controller is compared with the setpoint F of the feedwater flow rate of the condenser-side fuel heating system. SVC The larger value is taken as the setpoint F for the feedwater flow rate of the waste heat boiler side fuel heating system. SVH To prevent F SVH Less than F SVC Once the gas turbine power generation exceeds 125MW and the return water temperature of the fuel heating system is below 140℃, F SVH Less than F SVC Under the control of the third PID controller, the FCVH will gradually shut down, and all feedwater from the fuel heating system will return to the condenser, resulting in energy waste. The third PID controller is based on the setpoint F of the feedwater flow rate of the fuel heating system on the waste heat boiler side. SVH The opening degree of the waste heat boiler-side flow regulating valve FCVH is calculated based on the actual feedwater flow rate F of the fuel heating system, and the corresponding opening degree command U of the waste heat boiler-side flow regulating valve FCVH is output. H This forms a cascade control over the fuel heating temperature.

[0050] When the gas turbine power generation is less than 125MW or the return water temperature of the fuel heating system exceeds 140℃, the second and third PID controllers are both in tracking mode, and the FCVH remains fully off.

[0051] When the gas turbine power generation exceeds 125MW and the return water temperature of the fuel heating system is below 140℃, but the feedwater flow rate setpoint F of the waste heat boiler side fuel heating system is... SVH When the deviation from the actual feedwater flow rate F of the fuel heating system exceeds 10 t / h, the deviation is too large. Both the second and third PID controllers are in tracking mode. The tracking value of the second PID controller is the actual feedwater flow rate F of the fuel heating system, and the tracking value of the third PID controller is based on the gas turbine power generation P and the preset correspondence function between the gas turbine power generation and FCVH opening (the preset correspondence function between the gas turbine power generation and FCVH opening is shown in the figure). Figure 4 The calculated FCVH opening command U (as shown) H0 The opening command U H0 As the final FCVH opening instruction U H Cancel cascade control and adopt open-loop control of FCVH opening to ensure that the feedwater flow rate of the fuel heating system is within the normal range.

[0052] When F SVH When the deviation from F exceeds 10t / h, the second PID controller is in tracking mode, and F... SVH The setpoint F is equal to F, with a deviation of less than 10 t / h. The second and third PID controllers are still in tracking mode. SVH The flow rate F of the fuel heating system is equal to that of the actual water supply. After a preset delay time, the second and third PID controllers resume control and continue cascade control in a stable state.

[0053] Step S104, based on the actual water supply flow rate F of the fuel heating system and the fuel heating temperature setpoint T Foutsv Actual fuel heating temperature T Fout Fuel flow rate F F and the outlet temperature T of the medium-pressure economizer IE Calculate the opening degree of the three-way flow control valve FCVT.

[0054] Specifically, in this embodiment of the invention, the fuel heating temperature setpoint T is... Foutsv Compared with the actual fuel heating temperature T Fout The difference is input to the fourth PID controller; the actual feedwater flow rate F and fuel flow rate F of the fuel heating system are obtained. F and the outlet temperature T of the medium-pressure economizer IE Each of the three has its corresponding feedforward coefficient, and the feedforward control quantities of the three are obtained based on their respective feedforward systems. The feedforward control quantities of the three are then combined with the output of the fourth PID controller to obtain the opening command U of the three-way flow control valve FCVT. T The actual water supply flow rate F and fuel flow rate F of the fuel heating system.F and the outlet temperature T of the medium-pressure economizer IE The corresponding feedforward coefficients are determined based on on-site commissioning. In this embodiment of the invention, the FCVT is activated in advance when changes occur in fuel flow rate, fuel heating system feedwater flow rate, and medium-pressure economizer outlet temperature, thereby reducing the impact of external disturbances on fuel heating temperature.

[0055] Step S105: Control the opening degree of the condenser-side flow regulating valve FCVC, the waste heat boiler-side flow regulating valve FCVH, and the three-way flow regulating valve FCVT according to different operating conditions to control the fuel heating temperature of the gas turbine.

[0056] Through the above steps S101-S105, this embodiment of the invention acquires monitoring data of the gas turbine and fuel heating system, uses a multi-PID controller to adjust the opening of FCVH and FCVC to control the feedwater flow of the fuel heating system, and adjusts the opening of the three-way valve FCVT to control the proportion of fuel being heated, thereby achieving precise control of the fuel heating temperature and reducing the impact of external interference on the fuel heating temperature.

[0057] In one specific embodiment, Figure 5 The diagram shows the FCVC opening control logic structure provided in an embodiment of the present invention, where P represents the gas turbine power generation capacity, F represents the actual measured feedwater flow rate of the fuel heating system, and F SVC U represents the setpoint for the feedwater flow rate of the condenser-side fuel heating system. C This indicates the opening command of the FCVC. (1A) is a function that calculates the setpoint of the feedwater flow rate of the condenser-side fuel heating system based on the gas turbine power generation (the function relationship is as follows). Figure 3 As shown in the figure, (2A) is a subtractor and (3A) is the first PID controller.

[0058] Based on the above FCVC opening control logic structure, function (1A) calculates the setpoint F of the feedwater flow rate of the condenser-side fuel heating system according to the gas turbine power generation. SVC The subtractor (2A) will subtract F SVC The difference between the actual feedwater flow rate F of the fuel heating system and the flow rate F is used to obtain the opening command U of FCVC via the first PID controller. C The opening degree of the FCVC is adjusted by the first PID controller to ensure that the feedwater flow rate of the fuel heating system reaches the desired value.

[0059] In one specific embodiment, Figure 6 The diagram shows the FCVH opening degree control logic structure provided in an embodiment of the present invention, wherein T Foutsv T represents the fuel heating temperature setpoint. Fout T represents the actual fuel heating temperature. WBF represents the return water temperature of the fuel heating system. SVH E represents the setpoint for the feedwater flow rate of the fuel heating system on the waste heat boiler side. n U represents the enable signal for the FCVH opening control method proposed in this embodiment of the invention. H U represents the final opening instruction of FCVH. H0 This represents the FCVH opening command, which is traditionally calculated directly from the functional relationship between the gas turbine power generation and the FCVH opening. (1B) is constant block 140, (2B) is constant block 125, (3B) and (12B) are subtractors, (4B) is the low-limit alarm module, (5B) is an AND logic block, (6B) and (14B) are the high-limit alarm modules, (7B) is the second PID controller, (8B) is a NOT logic block, and (9B) is a function that calculates the setpoint of the condenser-side fuel heating system feedwater flow from the gas turbine power generation. The functional relationship is as follows: Figure 3 As shown, (10B) is the maximum value module, (11B) is the OR logic block, (13B) is the absolute value module, (15B) is the constant block 10, (16B) is the OFF delay alarm module, and (17B) is the preset FCVH opening command U directly calculated from the gas turbine generator power. H0 The function, the functional relationship is as follows Figure 4 As shown, (18B) is the third PID controller, (19B) and (20B) are analog quantity selection modules, and (21B) is constant block 0. It should be noted that constant block 140 refers to the return water temperature of the fuel heating system being below 140℃, and constant block 125 refers to the gas turbine power generation exceeding 125MW. The above values ​​are related to the characteristics of the gas turbine, and the parameters of different units may be different. This invention uses this as an example and is not limited thereto.

[0060] Based on the above FCVH opening control logic structure, when the gas turbine power generation P exceeds 125MW, the high-limit alarm module (6B) is triggered to 1, and the fuel heating system return water temperature T... WB When the temperature is below 140℃, the low-limit alarm module (4B) is triggered to 1. At this time, the AND logic block (5B) outputs 1, and the NOT logic block (8B) outputs 0. This corresponds to the previous time step F. SVH Tracking F, deviation is 0, high limit alarm module (14B) is 0, E n A value of 0 indicates that the FCVH opening control method proposed in this application is enabled. Alternatively, if the output of logic block (11B) is 0, the second PID controller cancels the tracking state. The deviation between the fuel heating temperature setpoint (e.g., 220℃) and the actual fuel heating temperature is input to the second PID controller. Then, the output of the second PID controller is compared with the setpoint F of the condenser-side fuel heating system feedwater flow rate obtained directly from the gas turbine power generation. SVC The larger value is taken as the setpoint F for the feedwater flow rate of the waste heat boiler side fuel heating system.SVH To prevent F SVH Less than F SVC Once the gas turbine power generation exceeds 125MW and the return water temperature of the fuel heating system is below 140℃, F SVH Less than F SVC Under the control of the third PID controller, the FCVH will gradually shut down, and all feedwater from the fuel heating system will be returned to the condenser, resulting in energy waste. The third PID controller operates based on the FCVH... SVH The opening degree of FCVH is calculated based on the actual feedwater flow rate F of the fuel heating system. The analog quantity selection module (20B) selects the output of the third PID controller as the final opening degree command U of FCVH. H This forms a cascade control over the fuel heating temperature.

[0061] When the gas turbine power generation is less than 125MW or the return water temperature of the fuel heating system exceeds 140℃, the output of the non-logic block (8B) is 1, or the output of the logic block (11B) is 1. The second and third PID controllers are both in tracking state, and the analog selection module (20B) selects 0 as the final FCVH opening command U. H FCVH remains fully off.

[0062] When the gas turbine power generation capacity exceeds 125MW and the return water temperature of the fuel heating system is below 140℃, but F SVH When the deviation from F exceeds 10t / h, the deviation is too large, the output of the non-logic block (8B) is 0, while the output of the high-limit alarm module (14B) is 1. Therefore, the output of the OR logic block (11B) is 1, and both the second and third PID controllers are in tracking state. The tracking value of the second PID controller is the actual feedwater flow rate F of the fuel heating system, and the tracking value of the third PID controller is the FCVH opening command U directly calculated from the gas turbine power generation. H0 The analog selection module (20B) selects the output of the third PID controller, i.e., U. H0 As the final FCVH opening instruction U H Cancel cascade control and adopt open-loop control of FCVH opening to ensure that the feedwater flow rate of the fuel heating system is within the normal range.

[0063] When F SVH When the deviation from F exceeds 10t / h, the second PID controller is in tracking mode, and F... SVH Equal to F, with a deviation of less than 10t / h, under the action of the OFF delay module (16B), the second and third PID controllers are still in the tracking state. After 120s, the second and third PID controllers resume control and continue cascade control in a stable state.

[0064] When E nWhen the signal is 1, it indicates that the FCVH opening control method is no longer enabled, that is, the OR logic block (11B) is always 1, the second and third PID controllers are always in tracking state, and the output of the third PID controller tracks U. H0 Analog selection module (20B) selects U H0 For the final FCVH opening instruction U H The system reverts to the traditional open-loop control strategy that directly calculates the FCVH opening degree from the gas turbine's power generation. Typically, En is set to 1 manually by the operator, providing a double-safety setting. Even if the FCVH opening degree control logic provided in this embodiment malfunctions, the FCVH opening degree can be restored to the traditional open-loop control method, ensuring the realization of basic control functions.

[0065] In one specific embodiment, Figure 7 The diagram shows the FCVT opening degree control logic structure provided in an embodiment of the present invention, wherein F F T represents fuel flow rate. IE U represents the outlet temperature of the medium-pressure economizer. T This indicates the opening command of the FCVT. (1C) is the feedforward coefficient K1 for fuel flow, (2C) is the subtractor, (3C) is the fourth PID controller, (4C) is the feedforward coefficient K2 for fuel heating system feedwater flow, (5C) is the feedforward coefficient K3 for medium-pressure economizer outlet temperature, and (6C) and (7C) are adders.

[0066] Based on the above FCVT opening control logic structure, the fuel heating temperature setpoint T Foutsv Compared with the actual fuel heating temperature T Fout After subtraction (2C), the result is input to the fourth PID controller to calculate the FCVT opening. Based on this, the fuel flow rate F is introduced. F The feedwater flow rate F of the fuel heating system and the outlet temperature T of the medium-pressure economizer IE The feedforward coefficients K1, K2, and K3 need to be determined during on-site commissioning. The FCVT should activate in advance when changes occur in fuel flow rate, fuel heating system feedwater flow rate, and medium-pressure economizer outlet temperature, reducing the impact of external disturbances on fuel heating temperature.

[0067] Although embodiments of the invention 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 the invention, and such modifications and variations all fall within the scope defined by the appended claims.

Claims

1. A method for controlling the fuel heating temperature of a gas turbine, characterized in that, The method includes: Obtain the gas turbine power generation P, the actual feedwater flow rate F of the fuel heating system, and the fuel heating temperature setpoint T. Foutsv Actual fuel heating temperature T Fout Fuel flow rate F F Medium-pressure economizer outlet temperature T IE ; Based on the gas turbine power generation P, the preset setpoint function of the feedwater flow rate of the condenser-side fuel heating system, and the actual feedwater flow rate F of the fuel heating system, the opening degree of the condenser-side flow regulating valve FCVC is calculated. Based on fuel heating temperature setpoint T Foutsv Compared with the actual fuel heating temperature T Fout Calculate the feedwater flow setpoint F for the waste heat boiler side fuel heating system. SVH Then, the opening degree of the regulating valve FCVH is calculated based on the actual water supply flow F of the fuel heating system, thus forming a cascade control of FCVH; Based on the actual water supply flow rate F of the fuel heating system and the fuel heating temperature setpoint T Foutsv Actual fuel heating temperature T Fout Fuel flow rate F F and the outlet temperature T of the medium-pressure economizer IE Calculate the opening degree of the three-way flow control valve FCVT; The opening degrees of the condenser-side flow regulating valve FCVC, the waste heat boiler-side flow regulating valve FCVH, and the three-way flow regulating valve FCVT are controlled according to different operating conditions to control the fuel heating temperature of the gas turbine.

2. The method according to claim 1, characterized in that, The calculation of the opening degree of the condenser-side flow regulating valve FCVC based on the gas turbine power generation P, the preset setpoint function of the feedwater flow rate of the condenser-side fuel heating system, and the actual feedwater flow rate F of the fuel heating system includes: Based on the gas turbine power generation P and the preset setpoint function for the feedwater flow rate of the condenser-side fuel heating system, the setpoint value F for the feedwater flow rate of the condenser-side fuel heating system is obtained. SVC ; Set the feedwater flow rate F of the condenser-side fuel heating system SVC The difference between the actual feedwater flow rate F of the fuel heating system and the input to the first PID controller yields the opening command U of the condenser-side flow control valve FCVC. C .

3. The method according to claim 1 or 2, characterized in that, The fuel heating temperature setpoint T Foutsv Compared with the actual fuel heating temperature T Fout Calculate the feedwater flow setpoint F for the waste heat boiler side fuel heating system. SVH Then, the opening degree of the regulating valve FCVH is calculated based on the actual feedwater flow rate F of the fuel heating system, forming a cascade control of FCVH, including: Obtain the return water temperature T of the fuel heating system WB ; When the gas turbine power generation P is higher than the preset high limit threshold and the fuel heating system return water temperature T WB When the temperature is below the preset lower threshold, the fuel heating temperature setpoint T will be adjusted. Foutsv Compared with the actual fuel heating temperature T Fout The deviation is input to the second PID controller; The output of the second PID controller is compared with the setpoint F of the feedwater flow rate of the condenser-side fuel heating system. SVC The larger value is taken as the setpoint F for the feedwater flow rate of the waste heat boiler side fuel heating system. SVH ; The third PID controller is based on the set value F of the feedwater flow rate of the fuel heating system on the waste heat boiler side. SVH The opening degree of the waste heat boiler-side flow regulating valve FCVH is calculated based on the actual feedwater flow rate F of the fuel heating system, and the opening degree command U of the waste heat boiler-side flow regulating valve FCVH is output. H This forms a cascade control over the fuel heating temperature.

4. The method according to claim 3, characterized in that, Also includes: When the gas turbine power generation P is less than the preset high limit threshold or the fuel heating system return water temperature T WB When the flow rate exceeds the preset lower threshold, the second PID controller output tracks the actual feedwater flow rate F of the fuel heating system, and the third PID controller output tracks the flow rate U calculated from the gas turbine power generation P and the preset functional relationship between the gas turbine power generation and FCVH opening. H0 and U H0 As the opening command U of the FCVH flow regulating valve on the waste heat boiler side. H The cascade control was cancelled, and the opening degree of the waste heat boiler side flow regulating valve FCVH was controlled by an open loop.

5. The method according to claim 4, characterized in that, Also includes: When the set value of the feedwater flow rate of the waste heat boiler side fuel heating system is F SVH When the deviation from the actual water supply flow rate F of the fuel heating system exceeds a preset threshold, the second PID controller outputs a value that tracks the actual water supply flow rate F of the fuel heating system, and the third PID controller outputs a value that tracks the actual water supply flow rate U. H0 and U H0 As the opening command U of the FCVH flow regulating valve on the waste heat boiler side. H When both the second and third PID controllers are in tracking mode, the setpoint F for the feedwater flow rate of the waste heat boiler side fuel heating system is... SVH The actual water flow rate F of the fuel heating system is equal to that of the fuel heating system. After a preset delay time, the second and third PID controllers cancel tracking and resume cascade control.

6. The method according to any one of claims 3-5, characterized in that, Also includes: An enable signal is set. When the enable signal is activated, the second and third PID controllers are always in tracking state, and the output of the third PID controller tracks U. H0 and U H0 The final FCVH opening command U is used as the flow control valve on the waste heat boiler side. H .

7. The method according to claim 1 or 6, characterized in that, The actual water supply flow rate F and fuel heating temperature setpoint T of the fuel heating system are mentioned. Foutsv Actual fuel heating temperature T Fout Fuel flow rate F F and the outlet temperature T of the medium-pressure economizer IE Calculate the opening degree of the three-way flow control valve FCVT, including: fuel heating temperature setpoint T Foutsv Compared with the actual fuel heating temperature T Fout The difference is input to the fourth PID controller; Obtain the actual feedwater flow rate F and fuel flow rate F of the fuel heating system F and the outlet temperature T of the medium-pressure economizer IE Each has its corresponding feedforward coefficient, and the feedforward control quantity of the three is obtained based on their respective feedforward coefficients; By combining the feedforward control values ​​of the three controllers with the output of the fourth PID controller, the opening command U of the three-way flow control valve FCVT is obtained. T .

8. The method according to claim 7, characterized in that, The actual water flow rate F and fuel flow rate F of the fuel heating system F and the outlet temperature T of the medium-pressure economizer IE The corresponding feedforward coefficients are determined based on on-site debugging.

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