A gas turbine fuel switching control method and system

Abstract

The application discloses a kind of gas turbine fuel switching control method and system, it is related to gas turbine control technical field.The method includes: obtaining environmental temperature parameter and gas turbine load parameter in the operation process of gas turbine;According to the parameter determines fuel switching point;In starting speed stage control, gas turbine uses duty fuel to carry out diffusion combustion;When the load of gas turbine reaches the fuel switching point, enter fuel switching stage, gradually reduce duty fuel supply ratio, while increase main fuel supply ratio;After switching is completed, according to environmental temperature parameter and gas turbine load parameter determines duty fuel target ratio and secondary fuel target ratio, and adjusts corresponding fuel supply to maintain stable combustion.The application determines switching point by introducing the two-dimensional correlation of environmental temperature and gas turbine load, cooperates load hysteresis control and closed-loop adjustment mechanism based on dynamic pressure and vibration acceleration, realizes the smooth switching of multiple fuels of gas turbine under all operating conditions and efficient low-nitrogen combustion, significantly improves the safety and stability of unit operation.

Description

Technical Field

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

[0002] Gas turbines are core power equipment that converts the chemical energy of fuel into mechanical energy, and are widely used in power generation, industrial drives, and other fields. With the diversification of energy structures, gas turbines need to be able to operate with multiple fuels. The control quality of the fuel switching process directly determines the unit's operational safety, economy, and environmental emission levels, making it an important research direction for gas turbine control technology.

[0003] Existing gas turbine fuel switching control generally uses fixed switching parameters and control logic, which makes it difficult to adaptively adjust to changes in operating conditions. During the switching process, problems such as unstable combustion and excessive nitrogen oxide emissions are prone to occur. There is a lack of systematic solutions for the coordinated control of multiple fuel channels, and the transition smoothness between different combustion modes is insufficient. At the same time, there is a lack of real-time feedback and adjustment mechanisms for combustion status and comprehensive strategies for dealing with abnormal operating conditions. The reliability and adaptability of unit operation need to be improved. Summary of the Invention

[0004] This invention provides a gas turbine fuel switching control method and system to solve the problems in the prior art where gas turbine fuel switching uses a fixed switching point and switching rate, cannot adaptively adjust according to ambient temperature and unit load, lacks systematic coordinated control of multiple fuel channels, and is prone to unstable combustion and NO during the switching process. x The problems include excessive emissions, lack of real-time feedback and adjustment of combustion status and comprehensive safety strategies for abnormal operating conditions, and insufficient reliability of unit operation.

[0005] To achieve the above objectives, one embodiment of the present invention provides a gas turbine fuel switching control method, comprising the following steps: Operating parameter acquisition step: acquiring ambient temperature parameters and gas turbine load parameters during gas turbine operation; Fuel switching point determination step: determining the fuel switching point under the corresponding operating condition based on the ambient temperature parameters and gas turbine load parameters; Start-up acceleration control step: during the gas turbine start-up acceleration phase, controlling the gas turbine to use standby fuel for diffusion combustion to establish a stable combustion state; Fuel switching control step: when the gas turbine load reaches the fuel switching point, entering the fuel switching phase, coordinating the standby fuel control channel and the main fuel control channel, gradually reducing the standby fuel supply ratio and increasing the main fuel supply ratio, so that the gas turbine switches from standby fuel combustion mode to main fuel combustion mode; Fuel ratio adjustment step: after fuel switching is completed, determining the standby fuel target ratio and the secondary fuel target ratio based on the ambient temperature parameters and gas turbine load parameters, and adjusting the standby fuel and secondary fuel supply according to the standby fuel target ratio and the secondary fuel target ratio to maintain stable combustion in the gas turbine.

[0006] Optionally, the fuel switching point is determined by a pre-established correspondence between ambient temperature parameters, gas turbine load parameters and fuel switching points; the correspondence is obtained by conducting combustion tests under multiple ambient temperature conditions and multiple gas turbine load conditions, and the fuel switching point corresponding to different operating conditions is determined based on the combustion stability state and the operating response during the fuel switching process.

[0007] Optionally, the target ratio of on-duty fuel and the target ratio of secondary fuel are determined through a pre-established fuel ratio correspondence. The fuel ratio correspondence includes on-duty fuel ratio data and secondary fuel ratio data corresponding to different gas turbine loads under different ambient temperatures. The pre-established fuel ratio correspondence is constructed using a two-layer interpolation architecture, specifically including: extracting the correspondence between actual load and fuel ratio under multiple preset discrete ambient temperatures; for a fixed actual load point, generating a temperature-ratio interpolation function based on the fuel ratio values ​​under different ambient temperatures; acquiring the current ambient temperature in real time, and calculating the target ratio of on-duty fuel and the target ratio of secondary fuel under the current operating conditions through the temperature-ratio interpolation function.

[0008] Optionally, the gas turbine generates a total fuel control signal based on the total fuel demand signal and distributes the total fuel control signal to the shift fuel control channel, the main fuel control channel, and the secondary fuel control channel. During fuel switching, the fuel supply of the three fuel control channels is coordinated and adjusted to match the total fuel supply of the gas turbine with the current operating load. The coordinated adjustment of the fuel supply of the three fuel control channels satisfies the following linkage rules: the sum of the shift fuel supply, the main fuel supply, and the secondary fuel supply is equal to the total fuel control signal in real time; when the shift fuel or secondary fuel supply ratio bias is adjusted, the main fuel supply ratio changes in the opposite direction synchronously.

[0009] Optionally, the fuel switching process includes a load increase fuel switching process and a load decrease fuel switching process; during the load decrease fuel switching process, load hysteresis control is set according to the fuel switching point to make the fuel switching point corresponding to the load decrease fuel switching process different from the fuel switching point corresponding to the load increase fuel switching process, so as to avoid the gas turbine repeatedly switching near the fuel switching point.

[0010] Optionally, during the process of adjusting the supply of standby fuel and secondary fuel according to the target ratio of standby fuel and the target ratio of secondary fuel, the dynamic pressure signal of the combustion chamber and the vibration acceleration signal of the combustion cylinder are acquired, and the combustion stability is determined according to the dynamic pressure signal and the vibration acceleration signal; when combustion instability is detected, the target ratio of standby fuel and / or the target ratio of secondary fuel are adjusted to change the main fuel supply ratio so that the combustion state can be restored to stability.

[0011] Optionally, determining the combustion stability includes: performing frequency analysis on the dynamic pressure signal and vibration acceleration signal; identifying the combustion state of the main fuel based on the signal change characteristics within different frequency ranges; and adjusting the fuel supply ratio based on the combustion state.

[0012] Optionally, identifying the main fuel combustion state includes: judging the trend of main fuel combustion state change based on the amplitude change trends of low-frequency range signals and high-frequency range signals; when the main fuel combustion state is detected to deviate from the stable combustion region, changing the combustion state by adjusting the shift fuel supply ratio and / or the secondary fuel supply ratio.

[0013] Optionally, abnormal operating condition control steps are also included: real-time acquisition of the gas turbine operating status; when a gas turbine load shedding state is detected, the secondary fuel supply is shut down and the fuel supply state is adjusted to the standby fuel stable combustion mode; when a gas turbine trip state is detected, the secondary fuel supply is shut down while performing fuel cut-off control and the standby fuel supply is restored.

[0014] On the other hand, a gas turbine fuel switching control system is also provided to implement the above-mentioned gas turbine fuel switching control method, comprising: an operating parameter acquisition module for acquiring ambient temperature parameters and gas turbine load parameters during gas turbine operation; a fuel switching point determination module connected to the operating parameter acquisition module for determining the fuel switching point based on the ambient temperature parameters and gas turbine load parameters; a fuel switching control module connected to the fuel switching point determination module for controlling the switching between standby fuel and main fuel when the gas turbine load reaches the fuel switching point; and a fuel ratio adjustment module connected to the fuel switching control module for determining the target ratio of standby fuel and the target ratio of secondary fuel based on the ambient temperature parameters and gas turbine load parameters, and adjusting the supply ratio of standby fuel and secondary fuel to maintain stable combustion in the gas turbine.

[0015] The present invention provides a gas turbine fuel switching control method and system that can adaptively adjust the timing of fuel switching and the distribution ratio of each fuel channel according to the ambient temperature and unit load, so as to achieve a smooth transition between different combustion modes, effectively suppress combustion fluctuations during the switching process and reduce nitrogen oxide emissions; maintain a reasonable air-fuel ratio through the coordinated management of multiple fuel channels, avoid frequent switching of the unit near the switching conditions, and combine online feedback adjustment of combustion status and rapid and safe switching mechanism for abnormal conditions to comprehensively improve the stability, environmental performance and adaptability of gas turbine operation. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in this invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In the drawings: Figure 1 This is a schematic diagram of the gas turbine fuel supply control structure provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the gas turbine start-up speed-up and fuel switching control logic provided in an embodiment of the present invention; Figure 3 This is a control schematic diagram of determining the fuel switching point based on ambient temperature parameters and gas turbine load parameters provided in an embodiment of the present invention; Figure 4 This is a schematic diagram of fuel ratio adjustment and combustion stability feedback control provided in an embodiment of the present invention; Figure 5 This is a schematic diagram of the double-layer interpolation of the fuel distribution ratio of a gas turbine provided in an embodiment of the present invention. Detailed Implementation

[0017] The specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit the scope of the present invention.

[0018] It should be noted that the acquisition, transmission, storage, use, and processing of data in the technical solution of this application all comply with the relevant provisions of national laws and regulations. In the embodiments of this application, certain existing industry solutions such as software, components, and models may be mentioned. These should be considered exemplary, intended only to illustrate the feasibility of implementing the technical solution of this application, and do not imply that the applicant has already used or necessarily used such solutions.

[0019] The following is combined with Figures 1-5 This invention is described in detail.

[0020] like Figure 1 As shown, this embodiment provides a gas turbine fuel switching control method, which is applied to a gas turbine fuel supply system having a standby fuel control channel, a main fuel control channel, and a secondary fuel control channel. The gas turbine fuel supply system includes a fuel supply module, a fuel control module, and multiple fuel control channels. The fuel supply module supplies fuel to the gas turbine, and the fuel control module generates corresponding fuel control signals based on the gas turbine's operating status and adjusts the fuel supply process through different fuel control channels. In this embodiment, the fuel control channels include a standby fuel control channel, a main fuel control channel, and a secondary fuel control channel. By coordinating and adjusting the fuel supply ratios of different fuel control channels, a smooth transition from the stable combustion state during startup to the normal operating state of the gas turbine is achieved. The standby fuel uses diffusion combustion to provide a stable combustion basis during startup and abnormal operating conditions; the main fuel uses premixed combustion, which effectively reduces nitrogen oxide generation through uniform fuel-air mixing and is the core combustion mode during normal unit operation.

[0021] Specifically, during gas turbine operation, the ambient temperature parameters and turbine load parameters are first acquired. The ambient temperature parameters characterize the temperature state of the gas turbine's operating environment, while the turbine load parameters characterize the current output power demand of the gas turbine. In one embodiment, the ambient temperature parameters can be acquired using temperature detection elements installed in the gas turbine's operating environment, and the turbine load parameters can be acquired based on load detection signals from the gas turbine's operation control system. By simultaneously acquiring both the ambient temperature parameters and the turbine load parameters, the current operating condition of the gas turbine can be determined, providing a basis for subsequently determining the fuel switching point.

[0022] like Figure 3As shown, after acquiring the ambient temperature parameters and gas turbine load parameters, the fuel switching point is determined based on these parameters. In this embodiment, the fuel switching point is not a fixed single load value, but a control parameter dynamically determined according to different operating conditions. Specifically, by pre-establishing the correspondence between the ambient temperature parameters, gas turbine load parameters, and fuel switching points, this correspondence can be quantified using the two-dimensional interpolation function FX1(T,LOAD), where T is the ambient temperature parameter and LOAD is the gas turbine load parameter. The fuel switching point corresponding to the load increase process can be expressed as: LOAD_switch_R=FX1(T,LOAD). During the actual operation of the gas turbine, based on the currently acquired ambient temperature parameters and gas turbine load parameters, the fuel switching point matching the current operating condition is determined from the correspondence.

[0023] When establishing the correspondence, combustion tests can be conducted under multiple ambient temperature conditions and multiple gas turbine load conditions to obtain the changes in the combustion state of the gas turbine under different operating conditions. Based on combustion stability, operational response during fuel switching, and the results of changes in combustion state, the corresponding fuel switching point can be determined. By establishing the correspondence between ambient temperature parameters, gas turbine load parameters, and fuel switching points, the gas turbine can select a suitable fuel switching timing according to the actual operating environment and load conditions, avoiding the problem of premature or delayed fuel switching due to changes in environmental conditions when using a fixed fuel switching point.

[0024] In one specific implementation, the correspondence between ambient temperature parameters, gas turbine load parameters, and fuel switching points can be established using a partitioned mapping method. Specifically, based on the temperature variation range of the gas turbine operating environment and the gas turbine load variation range, different ambient temperature conditions and different gas turbine load conditions are combined to form multiple operating conditions, and the corresponding fuel switching point for each operating condition is determined. For example, even if the gas turbine load parameters are the same, the fuel switching point corresponding to the gas turbine can be adjusted according to changes in combustion state when ambient temperature parameters are different; similarly, different fuel switching points can be determined based on the current load state when gas turbine load parameters are different. By establishing the above correspondence, the fuel switching point can simultaneously reflect the influence of both ambient temperature parameters and gas turbine load parameters.

[0025] Furthermore, during actual operation, after acquiring the current ambient temperature and turbine load parameters, the gas turbine control system matches these parameters against a corresponding relationship to determine the fuel switching point under the current operating conditions. When the ambient temperature or turbine load parameters change, the control system can re-determine the corresponding fuel switching point, thus enabling the fuel switching process to adapt to different operating conditions.

[0026] Furthermore, when determining the fuel switching point, the gas turbine control system acquires the current ambient temperature parameters and the current gas turbine load parameters, and matches the acquired data with a pre-established correspondence. When the gas turbine load corresponding to the current operating state reaches the determined fuel switching point, the control system enters the fuel switching control process; when the current gas turbine load has not reached the fuel switching point, the current fuel supply state is maintained to ensure the stability of the gas turbine operation.

[0027] With the above settings, this embodiment can determine the fuel switching point according to the actual operating environment and load status of the gas turbine. Compared with the control method of using a fixed load value for fuel switching, it can improve the matching degree between the fuel switching process and the actual operating conditions, and provide a control basis for the smooth switching of the standby fuel to the main fuel.

[0028] like Figure 2 As shown, Figure 2 This diagram illustrates the startup and acceleration control logic of a gas turbine, including speed channel switching branches and load channel switching branches. After determining the fuel switching point, when the gas turbine enters the startup and acceleration phase, the control system uses standby fuel for diffusion combustion. During the gas turbine startup process, because the operating conditions inside the combustion chamber have not yet reached stable operating conditions, standby fuel is needed to maintain combustion stability, enabling the gas turbine to complete ignition, acceleration, and initial load establishment. Therefore, during the startup and acceleration phase, the control system prioritizes opening the standby fuel control channel, allowing fuel to enter the combustion zone through this channel and utilize the standby fuel to form a stable diffusion combustion state.

[0029] Specifically, during the gas turbine startup and acceleration process, the control system adjusts the standby fuel supply based on the gas turbine speed and operational control requirements to maintain a stable flame state in the combustion chamber. As the gas turbine gradually accelerates and establishes its initial operating load, the control system continuously acquires the gas turbine load parameters and compares them with the previously determined fuel switching point. When the gas turbine load reaches the fuel switching point, the fuel switching phase begins.

[0030] During the fuel switching phase, the control system coordinates the control of the standby fuel control channel and the main fuel control channel, gradually reducing the standby fuel supply ratio while increasing the main fuel supply ratio, so that the gas turbine switches from the standby fuel combustion mode to the main fuel combustion mode. Compared with the switching method of directly shutting off the standby fuel and turning on the main fuel, this embodiment adopts a gradual adjustment of the fuel supply ratio, making the fuel supply changes during the combustion process smoother and avoiding combustion fluctuations caused by rapid changes in fuel supply status, thereby improving the stability of the fuel switching process.

[0031] Furthermore, during the fuel switching process, the control system adjusts the supply ratio of standby fuel and main fuel according to the current gas turbine load changes. In the initial stage of fuel switching, a certain proportion of standby fuel supply is maintained to maintain combustion stability, while the main fuel supply ratio is gradually increased, allowing the main fuel to gradually take on the main combustion task. As the gas turbine load continues to increase, the main fuel supply ratio gradually increases, while the standby fuel supply ratio gradually decreases, until the switch from standby fuel combustion mode to main fuel combustion mode is completed.

[0032] In one specific implementation, during the initial stage of fuel switching, the control system maintains a high proportion of standby fuel supply to ensure a stable flame foundation in the combustion chamber. As the switching process continues, the standby fuel supply proportion is gradually reduced, while the main fuel supply proportion is simultaneously increased, allowing the main fuel to gradually assume the primary combustion task. For example, the standby fuel supply proportion can be gradually reduced from the total fuel supply proportion corresponding to the start-up phase to a lower proportion, while the main fuel supply proportion increases accordingly to assume the primary combustion task. When the switching process is complete, the standby fuel supply proportion drops below 1%, and the main fuel supply proportion increases to above 99%, with the main fuel undertaking the main combustion and power tasks of the unit, and the standby fuel only maintaining a basic stable combustion function. Through this gradual fuel ratio conversion method, abrupt changes between fuel channels are avoided, improving the stability of the switching process.

[0033] In one specific implementation, the fuel switching process has a preset switching time. The control system adjusts the rate of decrease in the standby fuel supply ratio and the rate of increase in the main fuel supply ratio by setting a switching rate parameter. The switching time can be adjusted according to the gas turbine structural characteristics, fuel characteristics, and operating status, so that the fuel switching process meets the requirements of rapid response while avoiding combustion fluctuations caused by excessively rapid changes in fuel ratio. In a preferred embodiment, the control system controls the switching process through built-in timing logic, controlling the switching time to 30 to 40 seconds. The duration is adjusted through a unified switching rate parameter, taking into account both the combustion stability of the switching process and the load response speed of the unit. Fuel switching supports two operating modes: constant load switching and variable load switching. In constant load switching mode, the control system locks the gas turbine load command and completes the fuel ratio conversion under fixed load conditions. This is suitable for new unit combustion commissioning and parameter tuning tests, and facilitates the elimination of load fluctuation interference to optimize switching parameters. In variable load switching mode, the gas turbine load can continuously rise and fall at a set rate. The switching process is executed synchronously with the load change, which is suitable for normal unit operation conditions and can complete a smooth switch during dynamic load adjustments.

[0034] like Figure 1As shown, in this embodiment, the gas turbine uses a total fuel control signal for fuel supply control. Specifically, the gas turbine control system generates a total fuel demand signal based on the turbine's operating requirements, and then generates a corresponding total fuel control signal based on the total fuel demand signal. The total fuel control signal is then distributed to the shift fuel control channel, the main fuel control channel, and the secondary fuel control channel. In this embodiment, the total fuel control signal is defined as the CSO signal, with a range of 0-100%, used to characterize the total fuel demand of the gas turbine under its current operating conditions. Correspondingly, the output control signal of the shift fuel control channel is denoted as PLCSO, the output control signal of the main fuel control channel is denoted as MCSO, and the output control signal of the secondary fuel control channel is denoted as SFCSO. The three channel signals satisfy a strict constraint relationship: CSO = PLCSO + MCSO + SFCSO. The sum of the supply from the three fuel control channels strictly corresponds to the value of the total fuel control signal, ensuring that the total fuel supply always matches the unit load demand. Precise coordination of each fuel channel is achieved through a single-reference multi-channel control architecture.

[0035] By coordinating the control of multiple fuel control channels, a matching relationship is maintained between different fuel control channels.

[0036] During fuel switching, the control system coordinates and adjusts the fuel supply of the three fuel control channels according to the current operating load, ensuring that the total fuel supply of the gas turbine matches the current operating load. Specifically, the standby fuel control channel primarily provides a stable fuel supply during startup and combustion stability adjustment; the main fuel control channel provides the main fuel supply during normal operation; and the secondary fuel control channel further adjusts the fuel supply status based on operating conditions. This multi-channel coordinated fuel control method maintains the continuity of the gas turbine's output load during fuel mode switching.

[0037] Furthermore, such as Figure 2 As shown, the fuel switching process includes an increase-load fuel switching process and a decrease-load fuel switching process. During the increase-load fuel switching process, when the gas turbine load changes from low to high and reaches the fuel switching point, a switch from the standby fuel combustion mode to the main fuel combustion mode is executed. During the decrease-load fuel switching process, when the gas turbine load changes from high to low and approaches the fuel switching area, load hysteresis control is set according to the fuel switching point to distinguish the fuel switching point corresponding to the decrease-load fuel switching process from the fuel switching point corresponding to the increase-load fuel switching process.

[0038] Specifically, by setting load hysteresis control, the gas turbine has a certain switching range during load changes. The fuel switching point corresponding to the load reduction process can be expressed as: LOAD_switch_D = FX1(T,LOAD) - 2MW. In a preferred embodiment, the switching point during the load reduction process is 2MW lower than the switching point during the load increase process, forming a clear hysteresis range. When the gas turbine load fluctuates slightly near the fuel switching point, it will not immediately trigger repeated fuel mode switching. Instead, fuel status adjustment will be performed after the corresponding load increase or load decrease switching conditions are met. Through this method, frequent switching of the gas turbine near the fuel switching point due to load fluctuations can be avoided, improving the stability and reliability of the fuel control process.

[0039] In this embodiment, by employing shift fuel diffusion combustion control during the acceleration phase, proportional regulation control during the fuel switching phase, and coordinated control across multiple fuel control channels, the gas turbine can smoothly transition between fuel modes based on actual operating conditions. The fuel switching point is determined based on ambient temperature and turbine load parameters, and the fuel switching process is executed according to the current load condition, enabling the fuel switching process to adapt to different operating conditions and improving the combustion stability of the gas turbine during operation.

[0040] like Figure 4 As shown, after the fuel switch is completed, the gas turbine enters a stable operation phase. At this time, it is necessary to further adjust the fuel supply ratio according to different operating conditions to maintain stable combustion. After the main fuel switch is completed and the unit load reaches a stable state, secondary fuel is gradually introduced. The introduction of secondary fuel adopts a gradual approach to increase the supply ratio, avoiding sudden changes in the fuel channel state from impacting the combustion state in the combustion chamber. After the fuel switch is completed, the target ratio of the standby fuel and the target ratio of the secondary fuel are determined based on the ambient temperature parameters and the gas turbine load parameters. The supply of standby fuel and secondary fuel is adjusted according to the target ratios of standby fuel and secondary fuel. By rationally allocating the ratio of standby fuel to secondary fuel, the air-fuel ratio in the main combustion zone is maintained within a reasonable range, taking into account both combustion stability and low nitrogen emission requirements.

[0041] like Figure 5 As shown, in a preferred embodiment, the fuel ratio correspondence is constructed using a two-layer interpolation architecture, which differs from the conventional temperature correction coefficient conversion method. The construction process is as follows: First, through combustion tests covering the entire temperature range from low winter temperatures to high summer temperatures, multiple sets of discrete ambient temperatures (e.g., 5℃, 10℃, 15℃, 20℃, 30℃, 40℃) are obtained, representing the load-ratio interpolation relationship between the actual load of the gas turbine and the corresponding fuel ratio, i.e., PL% = (LOAD) and SF%= (LOAD). Next, for any fixed load point, extract the fuel percentage values ​​corresponding to different ambient temperatures (e.g., A1 at 5℃, A2 at 10℃…A6 at 40℃), and generate the temperature-percentage interpolation relationship PL%= for that load point. (T). During actual unit operation, based on real-time ambient temperature and actual load, the reference values ​​for the proportion at each known temperature are first obtained through load-proportion interpolation, and then the target proportion of standby fuel and the target proportion of secondary fuel under the current operating conditions are calculated through temperature-proportion interpolation. This construction method does not require converting test data into temperature correction coefficients and can directly update the corresponding interpolation relationship based on the test results at a single temperature. After a single test, only the interpolation curves corresponding to adjacent temperatures need to be corrected to complete parameter iteration, reducing the accumulation of errors in the data conversion process. At the same time, it simplifies the parameter tuning process in the combustion commissioning of new models and improves the update efficiency of control parameters and the final control accuracy.

[0042] The advantage of this method is that, after the test is completed on the same day, the first-level interpolation curve in the control logic corresponding to the ambient temperature can be directly modified based on the test results. For example, if the ambient temperature on that day is 37℃, then only the "load-percentage" interpolation curves for 40℃ and 30℃ need to be corrected so that the interpolation result for 37℃ falls within the test data range. There is no need to convert the test data into a temperature correction coefficient, avoiding error accumulation during data processing, and simplifying the parameter tuning process in the combustion debugging of new models.

[0043] Specifically, the control system pre-establishes a fuel ratio correspondence, which includes standby fuel ratio data and secondary fuel ratio data corresponding to different gas turbine loads under different ambient temperatures. During gas turbine operation, the control system acquires the current ambient temperature parameters and gas turbine load parameters, and determines the corresponding standby fuel target ratio and secondary fuel target ratio in the fuel ratio correspondence based on the current operating conditions. By determining the fuel target ratio according to the actual operating conditions, the fuel supply status can adapt to changes in environmental conditions and load, avoiding the deviation of the combustion state from the stable operating range caused by using a fixed fuel ratio.

[0044] In one implementation, the fuel ratio correspondence can be obtained through combustion tests under multiple ambient temperature conditions and multiple gas turbine load conditions. Specifically, under different ambient temperature conditions, the gas turbine is operated under different load states, and the combustion chamber operating status, combustion stability, and load response are recorded under different fuel supply ratios. Based on the test results, the corresponding standby fuel ratio data and secondary fuel ratio data for different operating conditions are determined, and a fuel ratio correspondence is formed. During actual operation, the corresponding fuel ratio data is retrieved based on the current ambient temperature parameters and gas turbine load parameters to obtain the standby fuel target ratio and secondary fuel target ratio applicable to the current operating state.

[0045] Furthermore, during the adjustment of the supply of standby fuel and secondary fuel according to the target ratio of standby fuel and secondary fuel, the dynamic pressure signal of the combustion chamber and the vibration acceleration signal of the combustion cylinder are continuously acquired, and the combustion stability is determined based on the dynamic pressure signal and the vibration acceleration signal. Specifically, the dynamic pressure signal of the combustion chamber is used to reflect the pressure fluctuation during combustion, and the vibration acceleration signal of the combustion cylinder is used to reflect the vibration changes during combustion. The control system comprehensively judges the combustion state of the gas turbine by simultaneously acquiring the above signals.

[0046] When determining the stable combustion state, frequency analysis is performed on the dynamic pressure signal and vibration acceleration signal. The combustion state of the main fuel is identified based on the signal variation characteristics within different frequency ranges, and the fuel supply ratio is adjusted accordingly. Specifically, frequency domain analysis is performed on the collected dynamic pressure signal and vibration acceleration signal to obtain the corresponding signal amplitude variations within different frequency ranges, and the current combustion state is determined to be outside the stable combustion region based on the signal amplitude variation characteristics.

[0047] like Figure 4 As shown, in one embodiment, identifying the combustion state of the main fuel specifically includes determining the direction in which the main fuel combustion state deviates from the stable combustion region based on the amplitude variation characteristics of the low-frequency band signal and the high-frequency band signal. When a significant amplitude change is detected in the low-frequency band signal and / or the high-frequency band signal, the control system determines the current main fuel combustion state based on the change trend within the corresponding frequency range, and adjusts the target proportion of the standby fuel and / or the target proportion of the secondary fuel to change the main fuel supply ratio and restore the combustion state to stability.

[0048] Among them, low-frequency band signals and high-frequency band signals refer to the signal characteristics obtained by dividing the combustion chamber dynamic pressure signal and combustion cylinder vibration acceleration signal into different frequency regions according to the frequency range after frequency analysis. Specifically, by performing frequency domain conversion on the collected dynamic pressure signal and combustion cylinder vibration acceleration signal, the corresponding signal amplitude changes in different frequency ranges are obtained, and the trend of combustion state changes is judged based on the signal change characteristics in different frequency ranges.

[0049] In one implementation, the low-frequency band signal is used to reflect pressure fluctuations and vibration changes within a lower frequency range during combustion, while the high-frequency band signal is used to reflect pressure fluctuations and vibration changes within a higher frequency range during combustion. When the amplitude of the low-frequency band signal shows a continuous increasing trend, it indicates that the main fuel combustion state may be deviating from the lean side of the stable combustion region; when the amplitude of the high-frequency band signal shows a significant increasing trend, it indicates that the main fuel combustion state may be deviating from the rich side of the stable combustion region. Based on the amplitude change trends of the low-frequency and high-frequency band signals, the control system determines the direction in which the current main fuel combustion state deviates from the stable combustion region, and adjusts the target proportion of the standby fuel and / or the target proportion of the secondary fuel accordingly.

[0050] It should be noted that the specific frequency ranges of the low-frequency band and the high-frequency band can be set according to the gas turbine model, combustion chamber structure and operating conditions. This implementation does not limit the specific frequency range, as long as the signal change characteristics in different frequency ranges can reflect the trend of combustion state changes.

[0051] In one specific implementation, the dynamic pressure signal and vibration acceleration signal are divided into 10 frequency bands after Fourier transform, each corresponding to a specific frequency range. Typically, an increase in the amplitude of low-frequency signals (e.g., below 500Hz) indicates that the main fuel is approaching a lean combustion state, while an increase in the amplitude of high-frequency signals (e.g., above 1000Hz) indicates that the main fuel is approaching a rich combustion state. The control system determines the direction of combustion state deviation based on these frequency band characteristics and adjusts the fuel supply ratio accordingly.

[0052] During the fuel adjustment test, each combustion chamber was equipped with a pulsating pressure sensor and a combustion chamber shell acceleration sensor to monitor the combustion status in real time. When the three-way fuel ratio distribution was not ideal, combustion vibration would occur, and the pulsating pressure signal and vibration acceleration signal would increase significantly. The test personnel manually adjusted the ratio offset of the standby fuel or secondary fuel and observed the changing trends of the signals in each frequency band, gradually approaching the upper and lower boundaries of the stable combustion range.

[0053] Combustion adjustment tests are typically conducted within a fixed time period each day, during which the ambient temperature fluctuates minimally and can be approximated as a constant temperature condition to eliminate the interference of temperature changes on the test results. The test process involves gradually increasing the load point by point to explore the boundaries. If, during the load increase process, the amplitude of the pulsating pressure signal or vibration acceleration signal exceeds the preset safety threshold, it indicates that the current fuel distribution ratio deviates from the stable combustion range, and the proportion of standby fuel or secondary fuel must be adjusted immediately for correction. If the combustion vibration still does not return to the safe range after adjustment, the test is quickly returned to the previous stable operating load point, the fuel distribution ratio is readjusted, and the load increase test continues. The above fuel ratio correspondence is gradually adjusted and optimized through combustion adjustment tests. During the adjustment process, the pulsating pressure sensor and shell acceleration sensor configured in each combustion chamber collect combustion status signals in real time. The two signals are divided into multiple frequency bands through Fourier transform as the basis for judging the combustion status. Boundary exploration was conducted at each load point under a set ambient temperature: by adjusting the proportion bias of standby fuel or secondary fuel, it was observed that when the amplitude of the low-frequency band signal increased significantly, the corresponding main fuel combustion state was close to the lean combustion boundary; when the amplitude of the high-frequency band signal increased significantly, the corresponding main fuel combustion state was close to the rich combustion boundary; combined with the nitrogen oxide emission detection results, the stable combustion range under this load point was determined, and the median value of the stable combustion range was taken as the optimal fuel proportion under this ambient temperature and load, and updated to the corresponding interpolation relationship.

[0054] Fuel proportion adjustments follow a linkage rule: when adjusting the proportion bias of standby fuel or secondary fuel, the proportion of primary fuel changes inversely simultaneously, and the sum of the three is always equal to the total fuel baseline CSO. If it is necessary to maintain a constant primary fuel proportion, the proportion of standby fuel is reduced while increasing the proportion of secondary fuel, or vice versa. When the primary fuel is in a rich-fuel state and the proportion of standby fuel needs to be further reduced to optimize emissions, the reduced supply of standby fuel is allocated to secondary fuel, achieving nitrogen oxide emission optimization while maintaining a stable air-fuel ratio in the primary combustion zone.

[0055] During the test, if the pulsating pressure or vibration acceleration signal exceeds the threshold, it indicates that the current fuel distribution ratio deviates from the optimal combustion state. The test personnel will directly adjust the shift or secondary ratio offset manually. If the combustion vibration still does not improve, the load will be quickly returned to the previous safe load point, the control ratio will be readjusted, and the load will be increased again. If the load is safely increased to that load point, the upper and lower boundaries below that load point will be explored: by adjusting the shift or secondary ratio offset, the emergence of high-frequency band vibration indicates that the fuel-rich boundary of that load point is about to be reached, and the emergence of low-frequency band vibration indicates that the fuel-lean boundary has been reached. At the same time, combined with the NOx measurement value, the stable combustion range of the entire load range below the ambient temperature is determined. The middle line of this range is taken as the optimal control ratio at that ambient temperature and updated to the corresponding interpolation relationship.

[0056] Specifically, when the combustion stability assessment indicates that the current combustion state is trending away from the stable region, the control system does not directly change the overall fuel supply to the gas turbine. Instead, it modifies the fuel supply structure by adjusting the target proportions for standby fuel and secondary fuel. For example, when improved combustion stability is required, the standby fuel supply proportion can be appropriately adjusted to enhance combustion stabilization. Once the combustion state returns to a stable range, fuel supply control continues based on the target proportions corresponding to the ambient temperature parameters and the gas turbine load parameters.

[0057] By employing the aforementioned fuel ratio regulation and combustion stability feedback control methods, the gas turbine can dynamically adjust its fuel supply status based on actual operating conditions after completing fuel mode switching. Simultaneously, it combines dynamic pressure signals from the combustion chamber and vibration acceleration signals from the combustion chamber to provide feedback judgment on the combustion state, thereby improving the combustion stability of the gas turbine under different environmental conditions and load variations. Compared to methods that rely solely on a fixed fuel ratio for control, this implementation method can coordinate adjustments based on changes in operating parameters and combustion state feedback results, making fuel supply control more adaptable to actual operating conditions.

[0058] During gas turbine operation, in addition to normal startup, fuel switching, and stable operation control, corresponding fuel control measures are required for abnormal operating states such as load shedding and turbine shutdown to prevent combustion instability caused by fuel supply mismatch under abnormal conditions. This embodiment also includes an abnormal state control process, which acquires the gas turbine's operating status in real time and executes corresponding fuel control strategies based on different abnormal operating states.

[0059] Specifically, the control system acquires the gas turbine's operating status in real time and determines the current operating status based on the gas turbine's operating control signals, load changes, and unit operating status information. When a load shedding state is detected in the gas turbine, the control system executes the fuel control strategy for the load shedding state, discontinues secondary fuel supply, simultaneously discontinues main fuel supply, adjusts the shift fuel supply ratio to full value, and quickly returns to diffusion combustion mode to avoid combustion instability or even flameout caused by a sudden drop in load.

[0060] During load shedding, the gas turbine's output load demand decreases rapidly, causing a corresponding change in the fuel required by the combustion system. Maintaining the original fuel supply ratio could lead to a deviation from the stable combustion state. Therefore, upon detecting load shedding, the control system first discontinues secondary fuel supply to reduce the complexity of fuel supply regulation. Simultaneously, it adjusts the standby fuel supply ratio based on the current combustion state to maintain a stable flame state within the combustion chamber. Through this control method, the gas turbine can maintain combustion stability during rapid load changes.

[0061] like Figure 1 As shown, under another abnormal operating condition, when a gas turbine trip is detected, the control system executes fuel cut-off control (i.e., shuts down the turbine). Figure 1 The fuel shut-off valves 1 and 2 shown simultaneously shut off the secondary fuel supply and the main fuel supply, and restore the standby fuel supply status. The standby fuel channel maintains the final combustion control status before the shut-off, ensuring the orderly execution of fuel control during the shutdown process.

[0062] In a tripped state, the gas turbine needs to rapidly reduce its operating status. At this time, fuel cut-off control is used to limit the continued fuel input and simultaneously disconnect the secondary fuel supply to avoid multiple fuel control channels participating in regulation at the same time, which would affect the stability of the shutdown process. The standby fuel supply is restored to maintain the necessary combustion control status, so that the fuel control process meets the operating requirements in a tripped state.

[0063] Furthermore, such as Figure 1 As shown, this embodiment also provides a gas turbine fuel switching control system for implementing the above-described gas turbine fuel switching control method. The gas turbine fuel switching control system includes an operating parameter acquisition module, a fuel switching point determination module, a fuel switching control module, and a fuel ratio adjustment module.

[0064] The operating parameter acquisition module acquires ambient temperature and turbine load parameters during gas turbine operation and sends these parameters to the fuel switching point determination module. The fuel switching point determination module, connected to the operating parameter acquisition module, determines the fuel switching point based on the ambient temperature and turbine load parameters, enabling adjustments to the fuel switching process according to current operating conditions and implementing hysteresis switching control during load reduction.

[0065] The fuel switching control module is connected to the fuel switching point determination module. It controls the switching between standby fuel and main fuel when the gas turbine load reaches the fuel switching point, supporting both constant load switching and variable load switching operating modes. During fuel switching, the fuel switching control module controls the fuel supply ratio of different fuel control channels, gradually transitioning the gas turbine from standby fuel combustion mode to main fuel combustion mode.

[0066] The fuel ratio adjustment module is connected to the fuel switching control module. It determines the target ratio of standby fuel and the target ratio of secondary fuel based on ambient temperature and gas turbine load parameters, and adjusts the supply ratio of standby fuel and secondary fuel to maintain stable combustion in the gas turbine. During fuel ratio adjustment, the module can also adjust the target ratios of standby fuel and secondary fuel based on combustion stability assessment results, ensuring the combustion state remains within the stable operating range.

[0067] The combustion state monitoring module is connected to the fuel ratio adjustment module. It is used to collect dynamic pressure signals from the combustion chamber and vibration acceleration signals from the combustion cylinder. After performing frequency domain analysis on the signals, it determines the stable state of combustion and generates a fuel ratio correction command, which is then sent to the fuel ratio adjustment module.

[0068] The abnormal operating condition protection module is used to detect load shedding and tripping status in real time, trigger the safety switching logic of the corresponding fuel channel, and execute the rapid withdrawal of secondary fuel and main fuel and the reset control of the standby fuel.

[0069] In one implementation, the aforementioned modules can be implemented using a controller within the gas turbine control system. These modules communicate with each other via data communication to acquire operating parameters, determine fuel switching, adjust fuel ratios, and control abnormal conditions. The controller generates corresponding control commands based on the acquired operating parameters and combustion status information, and drives the corresponding fuel adjustment mechanisms through the fuel control channel to achieve automatic control of the gas turbine fuel supply process.

[0070] When using the gas turbine fuel switching control method provided in this embodiment, the ambient temperature parameters and turbine load parameters during gas turbine operation are first acquired, and the fuel switching point corresponding to the current operating condition is determined based on these parameters. During the gas turbine start-up and acceleration phase, the gas turbine is controlled to use standby fuel for diffusion combustion to establish a stable combustion state. When the turbine load reaches the fuel switching point, the fuel switching phase begins. By gradually reducing the standby fuel supply ratio and increasing the main fuel supply ratio, the gas turbine switches from standby fuel combustion mode to main fuel combustion mode. After the main fuel switching is completed and the unit load stabilizes, secondary fuel is gradually introduced. Based on ambient temperature and gas turbine load parameters, the system determines the target proportion of standby fuel and the target proportion of secondary fuel, and adjusts the corresponding fuel supply proportion. Simultaneously, it continuously acquires dynamic pressure signals from the combustion chamber and vibration acceleration signals from the combustion cylinder to assess the combustion stability. When the combustion state deviates from the stable range, the fuel supply proportion is adjusted. When the gas turbine experiences load shedding or tripping, it performs operations such as synchronous withdrawal of secondary fuel and primary fuel, adjustment of the standby fuel proportion, and fuel cutoff control according to the corresponding abnormal state. This enables full-process fuel switching control of the gas turbine during startup, switching, stable operation, and abnormal states.

[0071] The core parameters involved in this method, such as fuel switching point, switching rate, and target proportion of each fuel channel, can all be adjusted according to the structural and combustion characteristics of different combustion chambers. It is not only suitable for gas turbines of specific power levels, but can also be extended to other power levels and types of gas turbine units, demonstrating good versatility and scalability.

[0072] Through the above-described embodiments, this invention determines the fuel switching point based on ambient temperature and turbine load parameters, and achieves smooth switching of gas turbine fuel modes by coordinating the control of standby fuel, main fuel, and secondary fuel. Simultaneously, through fuel ratio correspondence and combustion stability feedback control, it improves the combustion stability of the gas turbine under different operating conditions, and enhances the adaptability of the gas turbine during operation through abnormal state control strategies. Compared to fixed switching points and fixed fuel ratio control methods, this invention can dynamically adjust the fuel supply strategy according to actual operating conditions, improving the reliability of the gas turbine fuel switching process.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. For those skilled in the art, adjustments can be made to the number of fuel control channels, the method of acquiring control parameters, and the implementation form of the control module according to actual application needs without departing from the technical concept of the present invention; all such adjustments should be included within the scope of protection of the present invention.

Claims

1. A gas turbine fuel switching control method, characterized in that, Includes the following steps: Steps for obtaining operating parameters: Obtain the ambient temperature parameters and gas turbine load parameters during the operation of the gas turbine; Fuel switching point determination steps: Determine the fuel switching point under the corresponding operating conditions based on the ambient temperature parameters and gas turbine load parameters; Start-up speed-up control steps: During the gas turbine start-up speed-up phase, the gas turbine is controlled to use standby fuel for diffusion combustion in order to establish a stable combustion state; Fuel switching control steps: When the gas turbine load reaches the fuel switching point, the fuel switching stage is entered. The duty fuel control channel and the main fuel control channel are coordinated and adjusted to gradually reduce the duty fuel supply ratio and increase the main fuel supply ratio, so that the gas turbine switches from the duty fuel combustion mode to the main fuel combustion mode. Fuel ratio adjustment steps: After the fuel switching is completed, the target ratio of standby fuel and the target ratio of secondary fuel are determined according to the ambient temperature parameters and the gas turbine load parameters, and the supply of standby fuel and secondary fuel is adjusted according to the target ratio of standby fuel and the target ratio of secondary fuel to maintain stable combustion of the gas turbine.

2. The gas turbine fuel switching control method according to claim 1, characterized in that, The fuel switching point is determined by a pre-established correspondence between ambient temperature parameters, gas turbine load parameters and fuel switching points. The correspondence is obtained by conducting combustion tests under multiple ambient temperature conditions and multiple gas turbine load conditions, and the fuel switching point corresponding to different operating conditions is determined based on the combustion stability and the operating response during the fuel switching process.

3. The gas turbine fuel switching control method according to claim 1, characterized in that, The target proportion of on-duty fuel and the target proportion of secondary fuel are determined through a pre-established fuel proportion correspondence. The fuel proportion correspondence includes on-duty fuel proportion data and secondary fuel proportion data corresponding to different gas turbine loads under different ambient temperatures. The pre-established fuel proportion correspondence is constructed using a two-layer interpolation architecture, specifically including: extracting the correspondence between actual load and fuel proportion under multiple preset discrete ambient temperatures; for a fixed actual load point, generating a temperature-proportion interpolation function based on the fuel proportion values ​​under different ambient temperatures; acquiring the current ambient temperature in real time, and calculating the target proportion of on-duty fuel and the target proportion of secondary fuel under the current operating conditions through the temperature-proportion interpolation function.

4. The gas turbine fuel switching control method according to claim 1, characterized in that, The gas turbine generates a total fuel control signal based on the total fuel demand signal and distributes the total fuel control signal to the duty fuel control channel, the main fuel control channel, and the secondary fuel control channel. During fuel switching, the total fuel supply of the gas turbine is matched with the current operating load by coordinating and adjusting the fuel supply of the three fuel control channels. The coordinated adjustment of the fuel supply of the three fuel control channels meets the following linkage rules: the sum of the duty fuel supply, the main fuel supply, and the secondary fuel supply is equal to the total fuel control signal in real time; when the duty fuel or secondary fuel supply ratio bias is adjusted, the main fuel supply ratio changes in the opposite direction synchronously.

5. The gas turbine fuel switching control method according to claim 1, characterized in that, The fuel switching process includes a load increase fuel switching process and a load decrease fuel switching process; During the load reduction fuel switching process, load hysteresis control is set according to the fuel switching point to distinguish the fuel switching point corresponding to the load reduction fuel switching process from the fuel switching point corresponding to the load increase fuel switching process, so as to avoid the gas turbine repeatedly switching near the fuel switching point.

6. The gas turbine fuel switching control method according to claim 1, characterized in that, During the process of adjusting the supply of standby fuel and secondary fuel according to the target ratio of standby fuel and the target ratio of secondary fuel, the dynamic pressure signal of the combustion chamber and the vibration acceleration signal of the combustion cylinder are acquired, and the combustion stability is determined according to the dynamic pressure signal and the vibration acceleration signal; when combustion instability is detected, the target ratio of standby fuel and / or the target ratio of secondary fuel are adjusted to change the main fuel supply ratio so that the combustion state can be restored to stability.

7. The gas turbine fuel switching control method according to claim 6, characterized in that, The determination of combustion stability includes: performing frequency analysis on the dynamic pressure signal and vibration acceleration signal; identifying the combustion state of the main fuel based on the signal change characteristics in different frequency ranges; and adjusting the fuel supply ratio based on the combustion state.

8. The gas turbine fuel switching control method according to claim 7, characterized in that, The identification of the main fuel combustion state includes: judging the trend of main fuel combustion state change based on the amplitude change trend of low-frequency range signal and high-frequency range signal; when the main fuel combustion state is detected to deviate from the stable combustion region, the combustion state is changed by adjusting the duty fuel supply ratio and / or the secondary fuel supply ratio.

9. The gas turbine fuel switching control method according to claim 1, characterized in that, It also includes abnormal operating condition control steps: Real-time acquisition of gas turbine operating status; When a load shedding state is detected in the gas turbine, the secondary fuel supply is stopped and the fuel supply status is adjusted to the stable combustion mode of the standby fuel. When a gas turbine trip is detected, the secondary fuel supply is shut down while the fuel cut-off control is executed, and the standby fuel supply is restored.

10. A gas turbine fuel switching control system, used to implement the gas turbine fuel switching control method according to any one of claims 1-9, characterized in that, include: The operating parameter acquisition module is used to acquire ambient temperature parameters and gas turbine load parameters during the operation of the gas turbine; A fuel switching point determination module, connected to the operating parameter acquisition module, is used to determine the fuel switching point based on ambient temperature parameters and gas turbine load parameters. A fuel switching control module, connected to the fuel switching point determination module, is used to control the switching between standby fuel and main fuel when the gas turbine load reaches the fuel switching point; The fuel ratio adjustment module, connected to the fuel switching control module, is used to determine the target ratio of standby fuel and the target ratio of secondary fuel based on ambient temperature parameters and gas turbine load parameters, and to adjust the supply ratio of standby fuel and secondary fuel to maintain stable combustion in the gas turbine.

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