Fuel oil control method for power generation type gas turbine in high-working-condition sudden load unloading process

Abstract

The invention provides a fuel oil control method for the high-working-condition sudden load unloading process of a power generation type gas turbine, and belongs to the technical field of gas turbine control. Continuously monitoring the power generation power of the power generation type gas turbine, when the tripping signal is effective and the power generation power is greater than or equal to the preset load operation, judging that the gas turbine has high-working-condition sudden load unloading, quitting the rotating speed closed-loop control mode and executing the fuel oil open-loop control mode at the moment; in the fuel oil open-loop control mode process, constant-speed-rate oil cutting is started to be executed, meanwhile, the minimum oil supply amount corresponding to the minimum oil pressure ratio limiting curve is executed, and the higher one of the fuel oil supply amount corresponding to the constant-speed-rate oil cutting and the minimum oil supply amount corresponding to the minimum oil pressure ratio limiting curve is selected for fuel oil control; the rotating speed of the power turbine is continuously monitored, and when the rotating speed of the power turbine is reduced to a first preset interval, the fuel oil open-loop control mode is quitted; and when the rotating speed of the power turbine continues to be reduced to a second preset interval, normal control is recovered.

Description

Technical Field

[0001] The present application belongs to the field of gas turbine control technology, and in particular relates to a fuel control method for a power generation type gas turbine during a sudden load unloading process under high operating conditions. Background Art

[0002] When a power generation gas turbine is operating in an isolated grid, such as in the field of ship integrated electric propulsion system and emergency power generation, the generator or power load failure will cause the circuit breaker to trip. At this time, the gas turbine loses all load instantly. The most severe case is that when the gas turbine is operating at 100% load, the generator load system circuit breaker trips, and the gas turbine suddenly unloads 100% load instantly. Due to the delay in the change of the gas turbine state, the power turbine output power has not changed when the gas turbine suddenly unloads 100% load instantly. The residual power of the power turbine rotor will cause the power turbine speed Np to increase rapidly. If there is no efficient and safe fuel control law in this process, the power turbine rotor will over-rotate at the least, which cannot meet the speed regulation performance requirements of the power generation gas turbine. At the worst, the power turbine rotor will spin fast, and the power turbine and generator structure will be damaged.

[0003] There are two main types of fuel control rules for the existing power generation gas turbine during the 100% load unloading process, namely, the speed closed-loop control mode and the fuel open-loop control mode. The speed closed-loop control mode uses the PID adjustment mode to control the fuel quantity according to the deviation ΔNp (ΔNp=Npgd-Np) between the power turbine speed Np and the power turbine speed setting value Npgd, the change rate d(Np) / dt of the power turbine speed Np, and other variables. In order to meet the requirements of the gas turbine speed regulation during the 100% load unloading process, most gas turbines will use a higher core engine speed reduction limit rate, dedicated dynamic process PID control parameters, etc. after determining that they have entered the 100% load unloading process. The fuel open-loop control mode is that when it is determined that a sudden unloading of 100% load has occurred, the fuel quantity control adopts open-loop control. The commonly used fuel open-loop control mode is to control the fuel quantity to decrease rapidly according to the set fuel quantity function curve (such as Wfg=f(Nghs) curve, Wfg=f(Nghs, W0) curve, where Wfg is the fuel quantity setting value, Nghs is the core engine converted speed, and W0 is the gas turbine inlet air flow). When the fuel quantity reaches the target value, the target fuel quantity is maintained until the Np speed descends and callbacks to the set interval, and then the normal Np speed closed-loop control is restored.

[0004] However, the existing speed closed-loop control mode has the following disadvantages during the sudden 100% load unloading process of the power generation gas turbine:

[0005] 1) There is a natural control delay defect, that is, the fuel quantity is controlled after the power turbine speed Np changes. At the same time, since the overshoot of the power turbine speed Np at the beginning of the sudden unloading of 100% load does not increase significantly, the reduction of the fuel quantity mainly comes from the differential control link of the power turbine speed change rate d(Np) / dt. The fuel quantity reduction rate is too small, and the key opportunity to quickly reduce the fuel quantity and quickly suppress the overshoot of the power turbine speed Np after the sudden unloading of 100% load is missed; and after the power turbine speed Np increases rapidly, the fuel quantity Wfg decreases rapidly in the speed closed-loop control mode, which can easily cause combustion and flameout problems due to too fast oil cutting;

[0006] 2) The PID control value obviously affects the control of the fuel quantity Wfg, and it is difficult to find the optimal solution for the PID control value of the dynamic process. It will bring huge test costs and test risks to explore the PID control value of the dynamic process that has a good match with the gas turbine through sudden load unloading tests.

[0007] Similarly, the existing fuel open-loop control mode also has the following disadvantages during the sudden unloading of 100% load of the power generation gas turbine:

[0008] 1) After the gas turbine enters the load rejection transient control process, the fuel quantity is immediately cut from the current value to the target value "cliff-like". Although in this process it will first be limited by the limited fuel supply corresponding to the minimum oil-gas ratio limit curve, the instantaneous and substantial reduction in the fuel quantity will inevitably lead to an instantaneous and drastic change in the oil-gas ratio in the combustion chamber, which is very likely to cause combustion flameout, combustion oscillation and other combustion instability and aerodynamic mismatch phenomena, which may cause emergency shutdown of the gas turbine at the least, and compressor surge, explosion after combustion flameout, etc. at the worst, causing damage to the gas turbine;

[0009] 2) The minimum oil-gas ratio limit curve determined by the combustion chamber flameout test ensures that the minimum amount of fuel is used during the load rejection process to improve the speed regulation performance of the gas turbine. However, since the oil-gas ratio is close to the combustion flameout boundary, it is easy to cause combustion flameout due to the rapid dynamic changes in the gas turbine load rejection process. Moreover, after the power turbine speed Np enters the downward callback, it is unnecessary to use too small a fuel amount to prompt the gas turbine state to quickly callback. On the contrary, it is easy to cause the power turbine speed Np to exceed the limit of the downward callback.

[0010] 3) The load rejection process of a gas turbine is a rapid dynamic change process. There is a certain delay and deviation in the W0 test, which causes the oil-gas ratio parameters to be distorted, and cannot play the expected role of using the minimum oil-gas ratio to accurately limit the minimum fuel amount in the load rejection process. Summary of the invention

[0011] The purpose of the present application is to provide a fuel control method for a power generation type gas turbine during a sudden load unloading process under high operating conditions, so as to solve or alleviate at least one problem in the background technology.

[0012] The technical solution of the present application is: a fuel control method for a power generation type gas turbine during a sudden load unloading process under high operating conditions, comprising:

[0013] Get the generator trip signal;

[0014] Continuously monitoring the power generation of the generator set of the power generation type gas turbine during operation, and when the generator trip signal is valid and the generator set of the power generation type gas turbine is operating at a load greater than or equal to a predetermined load, determining that the power generation type gas turbine has a high operating condition sudden load unloading, at which time the power generation type gas turbine exits the power turbine speed closed-loop control mode and starts to execute the fuel open-loop control mode;

[0015] In the fuel open-loop control mode, the oil cutting starting point is when the generator trip signal is valid, and the uniform rate oil cutting is started. The fuel amount of the uniform rate oil cutting process is Wf1=Wf-k*t, where Wf is the effective time t when the generator trip signal is received. 0 The amount of fuel, k is the oil cut rate, t is the effective time relative to receiving the generator trip signal t 0 At the same time, the minimum fuel supply Wfmin corresponding to the minimum oil pressure ratio limit curve Wfmin=f(Nghs, Pt3) is executed, and the higher of the fuel supply Wf1 corresponding to the uniform rate oil cut and the minimum fuel supply Wfmin corresponding to the minimum oil pressure ratio limit curve is selected for fuel control, where Nghs is the core engine converted speed, and Pt3 is the compressor outlet total pressure;

[0016] The power turbine speed Np of the power generation gas turbine in the fuel open-loop control mode is continuously monitored. When the power turbine speed Np descends and callbacks to the first predetermined interval, the fuel open-loop control mode is exited and the power turbine speed closed-loop control mode is restored to perform load shedding. When the power turbine speed Np continues to descend and callback to the second predetermined interval, it is considered that the high-operating condition sudden load unloading process of the gas turbine is completed and the gas turbine resumes normal control.

[0017] In an optional embodiment of the present application, the generator trip signal being invalid indicates that the generator set of the power generation type gas turbine has not tripped and shed load, and the generator trip signal being valid indicates that the generator set of the power generation type gas turbine has tripped and shed load.

[0018] In an optional implementation manner of the present application, the predetermined load is 70% or more.

[0019] In an optional implementation manner of the present application, when the generator trip signal is valid and the generator set of the power-generating gas turbine does not reach the predetermined load operation, the speed closed-loop control mode is maintained to complete the power-generating gas turbine load rejection control.

[0020] In an optional embodiment of the present application, if the power-generating gas turbine is a dual-rotor power-generating gas turbine, a bleed valve is arranged between the high-pressure and low-pressure compressors of the dual-rotor power-generating gas turbine, and when it is determined that a sudden load unloading occurs in a high-operating condition of the gas turbine, the bleed valve opens to ensure that the operating margin of the low-pressure compressor during the sudden load unloading process in a high-operating condition meets the operating requirements.

[0021] In an optional implementation manner of the present application, the oil cut rate k is selected to be 40% to 80% of the rated operating fuel volume of the generator gas turbine.

[0022] In an optional embodiment of the present application, the process of obtaining the minimum oil pressure ratio limiting curve is: first, the minimum oil-gas ratio corresponding to the combustion chamber flameout test is obtained, and then it is converted into the minimum oil pressure ratio of the gas turbine corresponding to the flameout test based on the relationship between the inlet air flow W0 and the compressor outlet total pressure Pt3 within the full operating range of the gas turbine. Then, based on the oil pressure ratio operating envelope obtained from the actual low-operating condition load rejection test or simulation results of the gas turbine, the minimum oil pressure ratio limiting curve is obtained based on the oil pressure ratio operating envelope combined with the safety operating margin.

[0023] In an optional embodiment of the present application, the process of determining the minimum fuel supply Wfmin corresponding to the minimum oil pressure ratio limit curve is as follows: based on the core engine converted speed Nghs at the current moment, interpolate the current minimum oil pressure ratio limit value Wfmin / Pt3 on the minimum oil pressure ratio limit curve, and then reversely calculate the minimum fuel supply Wfmin based on the (high-pressure) compressor outlet total pressure Pt3 at the current moment.

[0024] In an optional embodiment of the present application, a minimum fuel supply boundary value Wfbv is set during the fuel open-loop control mode, and the fuel supply Wf1 corresponding to the uniform rate oil cut or the minimum fuel supply Wfmin corresponding to the minimum oil pressure ratio limiting curve is not lower than the minimum fuel supply boundary value Wfbv during the fuel control process.

[0025] In an optional implementation manner of the present application, the first predetermined interval is less than or equal to 103% Npgd, and the second predetermined interval is less than or equal to 101% Npgd, wherein Npgd is the set speed of the power turbine.

[0026] The fuel control method of the present application has the following advantages:

[0027] 1) After a power generation gas turbine experiences a sudden load unloading (or a high load rejection) under high operating conditions and enters the fuel open-loop control mode, the fuel is first cut at a relatively fast uniform rate to achieve accurate following of the fuel regulating device, and achieve a good match between the fuel control law and the fuel regulating system, thereby avoiding the problems of combustion flameout, combustion oscillation, compressor stall, etc. caused by the large deviation of the actual fuel supply due to the large instantaneous fuel quantity change in the "cliff-like" oil cutting process in the prior art, thereby improving the operating safety of the gas turbine during the sudden load unloading process under high operating conditions, and achieving a reasonable balance between good speed regulation performance and stable operation of the gas turbine;

[0028] 2) Compared with the minimum oil-gas ratio limit curve in the prior art, the minimum oil pressure ratio limit curve adopts the (high-pressure) compressor outlet total pressure parameter Pt3 with high dynamic sensitivity, and abandons the gas turbine inlet air flow rate W0 parameter which will cause obvious delay and distortion in the rapid change process of the gas turbine state. Therefore, it is more suitable for the rapid change process of the gas turbine state such as high-operating condition sudden load unloading (or high-operating condition load rejection), and the fuel quantity control is more accurate and scientific;

[0029] 3) The formulation of the minimum oil pressure ratio limit curve leaves a certain safety margin on the basis of the minimum oil-gas ratio limit curve determined by the combustion chamber flameout test, so as to avoid the problem in the prior art that the minimum oil-gas ratio limit curve is set close to the combustion flameout boundary, which is easy to cause combustion flameout. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solution provided by the present application, the following is a brief introduction to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present application.

[0031] Figure 1 This is a schematic flow chart of the fuel control method of this application.

[0032] Figure 2 Schematic diagram of a minimum oil pressure ratio limit curve according to an embodiment of the present application.

[0033] Figure 3 Schematic diagram of the change of the minimum oil pressure ratio during a sudden unloading of 100% load according to an embodiment of the present application.

[0034] Figure 4 This is a schematic diagram of the change in fuel volume during a sudden unloading of 100% load according to an embodiment of the present application. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application.

[0036] In order to avoid the problem that the minimum oil-gas ratio limit curve in the existing fuel open-loop control mode is close to the combustion extinction boundary, which is easy to cause combustion extinction, and the gas turbine inlet air flow W0 in the oil-gas ratio is obviously distorted in the dynamic process when a power generation gas turbine suddenly unloads 100% of the load (or high operating condition load rejection), the present application proposes an efficient and safe fuel control method for a power generation gas turbine in a high operating condition sudden load unloading process, which can fully tap the dynamic performance potential of the gas turbine, achieve good speed regulation performance indicators of the gas turbine, and ensure the safe operation of the gas turbine generator set in the high operating condition sudden load unloading process.

[0037] like Figure 1 As shown, the fuel control method of the power generation type gas turbine (or simply gas turbine) in the high-operating condition sudden load unloading process of the present application includes the following process:

[0038] S100, obtaining a generator trip signal. When the generator trip signal is invalid, it indicates that the gas turbine generator set has not tripped and shed load. When the generator trip signal is valid, it indicates that the gas turbine generator set has tripped and shed load. According to the generator trip signal, it can be timely and accurately determined whether the gas turbine generator set has tripped and shed load.

[0039] S200, continuously monitors the power generation during the operation of the gas turbine generator set to determine the operating load when the gas turbine generator set trips. When the generator trip signal is valid and the gas turbine generator set is operating at a predetermined load, it is determined that a sudden load unloading occurs under high operating conditions in the power generation gas turbine. At this time, the power generation gas turbine is controlled to immediately exit the power turbine speed closed-loop control mode and start executing the fuel open-loop control mode.

[0040] When the generator trip signal is valid and the gas turbine generator set does not reach the predetermined load operation, the current power generation type gas turbine load rejection control can be completed in the power turbine speed maintaining closed-loop control mode.

[0041] In some embodiments of the present application, the predetermined load is generally 70% or more.

[0042] In some embodiments of the present application, for a dual-rotor power generation gas turbine, a bleed valve can be provided between the high-pressure and low-pressure compressors. When it is determined that a sudden load unloading occurs in a high-operating condition of the gas turbine, the bleed valve can be opened in time to ensure that the operating margin of the low-pressure compressor during the sudden load unloading process meets the operating requirements. At the same time, opening the bleed valve can also reduce the output torque of the power turbine rotor, thereby improving the speed regulation performance.

[0043] S300, during the fuel open-loop control mode, the fuel cut-off point is the time when the generator trip signal is valid, and the uniform rate fuel cut-off is started. The fuel volume of the uniform rate fuel cut-off process is Wf1=Wf-k*t, where Wf is the effective time t when the generator trip signal is received.0 The amount of fuel, k is the oil cut rate, t is the effective time relative to receiving the generator trip signal t 0 duration; at the same time, the minimum fuel supply Wfmin corresponding to the minimum oil pressure ratio limiting curve Wfmin=f(Nghs, Pt3) is executed, and the higher of the fuel supply Wf1 corresponding to the uniform rate oil cut and the minimum fuel supply Wfmin corresponding to the minimum oil pressure ratio limiting curve is selected for fuel control, that is, when at a certain moment (such as moment t1) the gas turbine control system cuts oil at a uniform rate and the Wf1 corresponding to is less than or equal to the minimum fuel supply Wfmin corresponding to the minimum oil pressure ratio at the current moment, the fuel open-loop control mode adopts the minimum oil pressure ratio control.

[0044] In the preferred embodiment of the present application, the oil cut rate k is generally 40% to 80% of the rated fuel volume of the gas turbine. For example, if the rated fuel volume of the gas turbine Wfr = 5000 L / h, the oil cut rate k can be set to between (2000 and 4000) L / h / s, which can be determined comprehensively according to the speed regulation performance index requirements, the dynamic characteristics of the gas turbine and the simulation calculation results.

[0045] like Figure 2 The figure shows a schematic diagram of a minimum oil pressure ratio limiting curve of an embodiment of the present application. The method for obtaining the minimum oil pressure ratio limiting curve includes the following process: first, the minimum oil-gas ratio corresponding to the flameout test of the combustion chamber is obtained, and then, according to the relationship between the inlet air flow rate W0 and the (high-pressure) compressor outlet total pressure Pt3 within the full operating range of the gas turbine (which can be combined with the steady-state results, transitional state results and simulation calculation results of the gas turbine, etc.), it is converted into the minimum oil pressure ratio of the gas turbine corresponding to the flameout test (dashed line curve), and then according to the oil pressure ratio operating envelope (dotted line curve) obtained from the actual low-operating load rejection test or simulation results of the gas turbine, the minimum oil pressure ratio limiting curve (solid line curve) is obtained in combination with a certain safety operating margin.

[0046] The method for determining the minimum fuel supply Wfmin through the minimum oil pressure ratio limit curve is as follows: based on the current core engine conversion speed Nghs, interpolate the current minimum oil pressure ratio limit value Wfmin / Pt3 on the minimum oil pressure ratio limit curve, and then reversely calculate the minimum fuel supply Wfmin based on the current (high-pressure) compressor outlet total pressure Pt3.

[0047] In the preferred embodiment of the present application, a minimum fuel supply boundary value Wfbv is set during the fuel control process using the fuel supply amount Wf1 corresponding to the uniform rate fuel cut or the minimum fuel supply amount Wfmin corresponding to the minimum oil pressure ratio limit curve. The fuel amount at any time cannot be lower than the minimum fuel supply boundary value Wfbv, that is, at a certain time t 2When the minimum fuel supply Wfmin corresponding to the minimum oil pressure ratio limit curve or the fuel quantity Wf1 in the uniform rate oil cutting process is less than or equal to the minimum fuel supply boundary value Wfbv, the fuel quantity is executed according to the minimum fuel supply boundary value Wfbv to ensure that the fuel quantity in the sudden unloading process of 100% load meets the minimum limit requirement and fully ensures combustion stability.

[0048] S400 continuously monitors the power turbine speed Np of the gas turbine in the fuel open-loop control mode. When a certain moment t 3 When the power turbine speed Np downwardly adjusts back to a predetermined interval (such as Np≤Npgd+3%Npgd), the fuel open-loop control mode is exited and the power turbine speed closed-loop control mode is restored to perform load shedding; when the power turbine speed Np continues to downwardly adjust back to a value closer to the power turbine speed set value Npgd (for example, Np≤Npgd+1%Npgd), it is considered that the gas turbine sudden unloading 100% load process is completed and the gas turbine returns to normal control.

[0049] like Figure 3 The schematic diagram of the change process of the fuel control mode on the minimum oil pressure ratio limit curve during the sudden load unloading process of the gas turbine under high operating conditions and Figure 4 The diagram of the fuel quantity variation curve during the sudden load unloading process of the gas turbine under high operating conditions is shown. In the present application, a minimum oil pressure ratio limit curve with a certain safety operating margin is used to limit the minimum fuel quantity during the sudden load unloading process under high operating conditions. The minimum oil pressure ratio uses the (high-pressure) compressor outlet total pressure parameter Pt3 which has high dynamic sensitivity and a high correlation with the gas turbine inlet air flow rate W0. This can not only enable the oil pressure ratio parameter to accurately characterize the oil-gas ratio value, but also avoid parameter distortion, thereby ultimately achieving real-time and precise control of the fuel quantity.

[0050] The fuel control method of the present application has the following advantages:

[0051] 1) After a power generation gas turbine experiences a sudden load unloading (or a high load rejection) under high operating conditions and enters the fuel open-loop control mode, the fuel is first cut at a relatively fast uniform rate to achieve accurate following of the fuel regulating device, and achieve a good match between the fuel control law and the fuel regulating system, thereby avoiding the problems of combustion flameout, combustion oscillation, compressor stall, etc. caused by the large deviation of the actual fuel supply due to the large instantaneous fuel quantity change in the "cliff-like" oil cutting process in the prior art, thereby improving the operating safety of the gas turbine during the sudden load unloading process under high operating conditions, and achieving a reasonable balance between good speed regulation performance and stable operation of the gas turbine;

[0052] 2) Compared with the minimum oil-gas ratio limit curve in the prior art, the minimum oil pressure ratio limit curve adopts the (high-pressure) compressor outlet total pressure parameter Pt3 with high dynamic sensitivity, and abandons the gas turbine inlet air flow rate W0 parameter which will cause obvious delay and distortion in the rapid change process of the gas turbine state. Therefore, it is more suitable for the rapid change process of the gas turbine state such as high-operating condition sudden load unloading (or high-operating condition load rejection), and the fuel quantity control is more accurate and scientific;

[0053] 3) The formulation of the minimum oil pressure ratio limit curve leaves a certain safety margin on the basis of the minimum oil-gas ratio limit curve determined by the combustion chamber flameout test, so as to avoid the problem in the prior art that the minimum oil-gas ratio limit curve is set close to the combustion flameout boundary, which is easy to cause combustion flameout.

[0054] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A fuel control method for a power generation type gas turbine during a sudden load unloading process under high operating conditions, characterized in that: include: Get the generator trip signal; Continuously monitoring the power generation of the generator set of the power generation type gas turbine during operation, and when the generator trip signal is valid and the generator set of the power generation type gas turbine is operating at a load greater than or equal to a predetermined load, determining that the power generation type gas turbine has a high operating condition sudden load unloading, at which time the power generation type gas turbine exits the power turbine speed closed-loop control mode and starts to execute the fuel open-loop control mode; During the fuel open-loop control mode, the oil cutting starting point is when the generator trip signal is valid, and the uniform rate oil cutting is started. The fuel amount of the uniform rate oil cutting process is Wf1=Wf-k*t, where Wf is the fuel amount at the effective time t0 when the generator trip signal is received, k is the oil cutting rate, and t is the duration relative to the effective time t0 when the generator trip signal is received; at the same time, the minimum oil pressure ratio limit curve Wfmin=f(Nghs, Pt3) corresponding to the minimum oil supply amount Wfmin is executed, and the higher of the fuel supply amount Wf1 corresponding to the uniform rate oil cutting and the minimum oil supply amount Wfmin corresponding to the minimum oil pressure ratio limit curve is selected for fuel control, where Nghs is the core engine converted speed, and Pt3 is the compressor outlet total pressure; The power turbine speed Np of the power generation gas turbine in the fuel open-loop control mode is continuously monitored. When the power turbine speed Np descends and callbacks to the first predetermined interval, the fuel open-loop control mode is exited and the power turbine speed closed-loop control mode is restored to perform load shedding. When the power turbine speed Np continues to descend and callback to the second predetermined interval, it is considered that the high-operating condition sudden load unloading process of the gas turbine is completed and the gas turbine resumes normal control.

2. The fuel control method for a power generation type gas turbine during a sudden load unloading process under high operating conditions as claimed in claim 1, characterized in that: The invalidity of the generator trip signal indicates that the generator set of the power generation type gas turbine has not tripped and shed load, and the validity of the generator trip signal indicates that the generator set of the power generation type gas turbine has tripped and shed load.

3. The fuel control method for a power generation type gas turbine during a sudden load unloading process under high operating conditions as claimed in claim 1, characterized in that: The predetermined load is 70% or more.

4. The fuel control method for a power generation type gas turbine during a sudden load unloading process under high operating conditions as claimed in claim 3, characterized in that: When the generator trip signal is valid and the generator set of the power generation type gas turbine does not reach the predetermined load operation, the power turbine speed closed-loop control mode is maintained to complete the power generation type gas turbine load rejection control.

5. The fuel control method for a power generation type gas turbine during a sudden load unloading process under high operating conditions as claimed in claim 1, characterized in that: If the power generation type gas turbine is a dual-rotor power generation type gas turbine, a bleed valve is arranged between the high-pressure and low-pressure compressors of the dual-rotor power generation type gas turbine. When it is determined that a sudden load unloading occurs under high operating conditions in the gas turbine, the bleed valve opens to ensure that the operating margin of the low-pressure compressor during the sudden load unloading process under high operating conditions meets the operating requirements.

6. The fuel control method for a power generation type gas turbine during a sudden load unloading process under high operating conditions as claimed in claim 1, characterized in that: The oil cutting rate k is selected to be 40% to 80% of the rated operating fuel volume of the generator gas turbine.

7. The fuel control method for a power generation type gas turbine during a sudden load unloading process under high operating conditions as claimed in claim 1, characterized in that: The process of obtaining the minimum oil pressure ratio limit curve is as follows: first, the minimum oil-gas ratio corresponding to the combustion chamber flameout test is obtained, and then the relationship between the inlet air flow W0 and the compressor outlet total pressure Pt3 within the full operating range of the gas turbine is converted into the minimum oil pressure ratio of the gas turbine corresponding to the flameout test, and then the oil pressure ratio operating envelope is obtained based on the actual low-operating load rejection test or simulation results of the gas turbine, and the minimum oil pressure ratio limit curve is obtained based on the oil pressure ratio operating envelope combined with the safety operating margin.

8. The fuel control method for a power generation type gas turbine during a sudden load unloading process under high operating conditions as claimed in claim 7, characterized in that: The process of determining the minimum fuel supply Wfmin corresponding to the minimum oil pressure ratio limit curve is as follows: based on the core engine conversion speed Nghs at the current moment, the minimum oil pressure ratio limit value Wfmin / Pt3 at the current moment is interpolated on the minimum oil pressure ratio limit curve, and then based on the current moment (high-pressure) compressor outlet total pressure Pt3, the minimum fuel supply Wfmin is calculated in reverse.

9. The fuel control method for a power generation type gas turbine during a sudden load unloading process under high operating conditions as claimed in claim 7 or 8, characterized in that: During the fuel open-loop control mode, a minimum fuel supply boundary value Wfbv is set. During the fuel control process, the fuel supply Wf1 corresponding to the uniform rate fuel cut or the minimum fuel supply Wfmin corresponding to the minimum oil pressure ratio limit curve is not lower than the minimum fuel supply boundary value Wfbv.

10. The fuel control method for a power generation type gas turbine during a sudden load unloading process under high operating conditions as claimed in claim 1, characterized in that: The first predetermined interval is less than or equal to 103% Npgd, and the second predetermined interval is less than or equal to 101% Npgd, wherein Npgd is a set speed of the power turbine.

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