A steam turbine governing stage nozzle area dynamic automatic correction system and method

Abstract

This invention discloses a dynamic automatic correction system for the nozzle area of ​​a steam turbine regulating stage, comprising: a detection module for real-time acquisition of operating parameters of the steam turbine regulating stage, including the pressure difference across the regulating valve, main steam flow rate, reheat steam temperature, unit power, and speed; and a control module, which is communicatively connected to the detection module and incorporates a load rate calculation model, a dynamic correction algorithm, and secondary correction logic. This invention ensures that the regulating valve opening remains within the high-efficiency range by dynamically correcting the nozzle area, combined with secondary correction logic. This verifies that throttling losses are reduced under low load conditions, directly reducing energy consumption and improving the unit's operational economy. Simultaneously, through high-frequency data acquisition, dynamic coefficient optimization, and flexible correction cycles, it achieves a "second-level" correction response. The specification clearly states that it can quickly meet the peak-shaving needs of the power grid and solve the problem of nozzle area decoupling from operating conditions under load fluctuations.

Description

Technical Field

[0001] This invention relates to the field of regulating stage nozzle technology, and specifically to a dynamic automatic correction system and method for the area of ​​a steam turbine regulating stage nozzle. Background Technology

[0002] The regulating stage is a core component in the energy conversion of a steam turbine, and the matching degree between its nozzle area and steam flow directly affects the unit's operating efficiency. Traditional steam turbine regulating stage nozzles mostly use a fixed design, which can only adapt to rated load conditions. When operating at low loads, several key problems arise:

[0003] The throttling loss is quite significant. When the load is low, the steam flow rate will decrease, while the nozzle area is fixed. This forces the regulating valve to be closed very slightly in order to control the flow rate. As a result, the throttling pressure difference will increase, leading to a large amount of energy loss, which has a very serious impact on the economic efficiency of the unit operation.

[0004] Traditional manual correction methods rely on maintenance personnel's experience to make judgments. As a result, the correction cycle is relatively long, making it difficult to respond promptly to dynamic fluctuations in grid load. This can easily lead to a disconnect between nozzle area and actual operating conditions, resulting in operational stability issues. Summary of the Invention

[0005] Therefore, the present invention provides a dynamic automatic correction system and method for the nozzle area of ​​a steam turbine regulating stage, in order to overcome the problems of the prior art.

[0006] This invention is implemented by the following technical solution:

[0007] A dynamic automatic correction system for the nozzle area of ​​a steam turbine regulating stage includes:

[0008] The detection module is used to collect the operating parameters of the turbine regulating stage in real time, including the pressure difference across the regulating valve, main steam flow, reheat steam temperature, unit power and speed.

[0009] The control module is connected to the detection module and has a built-in load rate calculation model, dynamic correction algorithm and secondary correction logic. It is used to receive the data collected by the detection module and process it to calculate the actual load rate β, dynamic empirical coefficient C(β) and optimal nozzle correction area S, and output control commands.

[0010] The execution module is communicatively connected to the control module and is used to receive the control commands and drive the nozzle blades to adjust to change the nozzle area. The execution module adopts a redundant configuration of main execution mechanism and backup execution mechanism.

[0011] The communication module is used to establish a signal transmission link between the detection module, control module and execution module, and a communication interface with the unit's central monitoring system is reserved.

[0012] The control module presets the nozzle area correction boundary as 0.8S0≤S≤1.2S0, where S is the original design nozzle area under rated operating conditions.

[0013] Preferably, the detection module includes:

[0014] The dual-redundant differential pressure sensor for the control valve is a high-precision capacitive differential pressure transmitter with a measurement range of 0-2MPa and an accuracy of ±0.05%FS. It is installed on the flanges before and after the control valve.

[0015] The high-temperature ultrasonic flow meter with dual redundancy configuration is a dual-channel insertion design and is installed on the main steam pipe at the inlet of the regulating stage.

[0016] A K-type thermocouple array, consisting of 12 thermocouples, is evenly arranged circumferentially along the annular support at the nozzle outlet.

[0017] The auxiliary sensor group includes a speed sensor, a power sensor, and a reheat steam temperature sensor.

[0018] Preferably, the control module includes an industrial-grade PLC or DCS controller, integrating a high-speed data acquisition card and a dedicated computing chip, with a data sampling frequency ≥100Hz, signal transmission delay ≤10ms, and controller response time ≤50ms. The dedicated computing chip pre-stores a data preprocessing program, uses the 3σ criterion to filter outliers, and performs noise reduction processing using a moving average algorithm.

[0019] Preferably, in the execution module, the main execution mechanism is a hydraulic drive mechanism controlled by an electro-hydraulic servo valve, corresponding to the nozzle area adjustment resolution, and the backup execution mechanism is a pneumatic actuator, which is installed in parallel with the main execution mechanism and automatically switches in case of failure.

[0020] Preferably, the communication module uses a Profinet bus to realize inter-module communication, and is configured with a ModbusTCP interface to interface with the unit's central monitoring system, supporting data upload and remote parameter configuration.

[0021] A method for dynamic automatic correction of the nozzle area of ​​a steam turbine regulating stage includes the following steps:

[0022] S1: System initialization, input the turbine rated parameters, including the original design nozzle area S0, rated load, design main steam flow rate G, design reheat steam temperature T, and regulating stage thermodynamic parameters. The weight coefficients k1, k2, and k3 of the load rate calculation model are determined by training with historical operating data of the unit.

[0023] S2: The detection module collects operating parameters in real time and transmits them to the control module via the communication module. The control module performs outlier filtering and noise reduction preprocessing on the collected data through a preset program.

[0024] S3: The control module calculates the actual load rate β through a multi-parameter load rate calculation model. The model is: β=k1·(Gactual / Gdesign)+k2·(Treheat / Tdesign)+k3·ΔPthrottle, where Gactual is the measured main steam flow rate, Treheat is the measured reheat steam temperature, and ΔPthrottle is the measured throttle pressure difference of the regulating valve.

[0025] S4: The control module calculates the dynamic empirical coefficient C(β), and the calculation formula is: C(β)=1.1+0.05sin(πβ / 100). When the load fluctuation frequency is >0.5Hz, the adaptive filtering algorithm is enabled to optimize C(β).

[0026] S5: The control module calculates the optimal nozzle correction area S according to the formula S=S0×(β / 100)×C(β), and verifies whether S is within the range of 0.8S0-1.2S0. If it exceeds the range, the corresponding boundary value is taken.

[0027] S6: The control module sends a control command to the execution module, and the execution module drives the nozzle blades to adjust to the correction area S;

[0028] S7: Detect the opening of the regulating valve after correction. If the opening is <70%, start the secondary correction logic: fine-tune C(β) by step size 0.02, with an interval of 2 seconds between each adjustment and recalculate S to perform the adjustment until the opening is ≥70% or the maximum number of adjustments is reached (10).

[0029] S8: Adaptively switches control modes based on unit load fluctuations to achieve continuous dynamic correction of nozzle area.

[0030] Preferably, the control mode in step S8 includes:

[0031] Automatic correction mode is the default mode. It will be automatically activated when β < 85%. The correction cycle is 5 seconds when the load is stable and 1 second when the load fluctuates greatly.

[0032] Emergency manual mode, activated when the sensor or actuator malfunctions, allows manual input of the target nozzle area within the range of 0.8S0-1.2S0, and the system will drive the adjustment.

[0033] In the remote operation and maintenance mode, the central monitoring system allows for remote viewing of operational data, automatic start / stop correction functions, and updating of weight coefficients k1, k2, and k3.

[0034] The adaptive operating mode automatically identifies stable low load (β=50%-75%), fluctuating low load (β fluctuation>±3% / min), or rated load (β≥85%), and adapts the accuracy correction, fast response, and stop correction strategies accordingly.

[0035] Preferably, in step S1, the weighting coefficients k1, k2, and k3 are determined through training with more than 1,000 sets of historical operating data of the unit, and the regulating stage thermodynamic parameters include a speed ratio of 0.3-0.45 and a reaction degree of 0.05-0.15.

[0036] Preferably, in step S3, when any sensor fails, the system automatically switches to the redundant sensor to collect data, with a switching transition time of ≤0.5s and records the running data for 5s before and after the failure time.

[0037] Preferably, in step S7, the nozzle blade adjustment stroke is monitored in real time during the secondary correction process, and an actuator fault alarm is triggered when the stroke deviation exceeds ±0.2mm.

[0038] The advantages of this invention are as follows: By dynamically correcting the nozzle area and combining it with secondary correction logic, the opening of the regulating valve is ensured to be within the high-efficiency range, verifying that throttling losses are reduced under low load, directly reducing energy consumption and improving the economic efficiency of unit operation; at the same time, through high-frequency data acquisition, dynamic coefficient optimization, and flexible correction cycle, a "second-level" correction response is achieved. The manual clearly states that it can quickly meet the peak-shaving needs of the power grid and solve the problem of nozzle area and operating conditions being out of sync under load fluctuations; furthermore, through efficient communication and multi-mode control, it ensures the coordination of detection, control, and execution modules; it supports remote data viewing and parameter updates, breaking through geographical limitations to improve operation and maintenance efficiency, and is flexible in operation and easy to monitor and manage. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 This is a diagram of the overall system architecture described in this invention;

[0041] Figure 2 This is a hardware configuration diagram of the detection module described in this invention;

[0042] Figure 3 This is a hardware and algorithm logic diagram of the control module described in this invention;

[0043] Figure 4 This is a schematic diagram of the redundant structure of the execution module described in this invention;

[0044] Figure 5 This is a flowchart illustrating the dynamic correction process described in this invention.

[0045] Figure 6 This is a schematic diagram of the redundancy protection principle described in this invention. Detailed Implementation

[0046] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 As shown,

[0048] Steam turbine regulating stage nozzle area dynamic automatic correction system

[0049] The system comprises a detection module, a control module, an execution module, a communication module, and an intelligent monitoring and control module. These modules work together to perform functions such as parameter acquisition, dynamic calculation, precise execution, and real-time monitoring. The overall architecture of the system is built according to the principle of modular design, which ensures that the functions of each part are independent and can operate in a coordinated and efficient manner.

[0050] The detection module's core function is to collect key operating parameters of the regulation stage in real time and accurately, thereby providing reliable data support for subsequent calculations. It also employs a redundant design to ensure continuous data acquisition. Its specific configuration is as follows:

[0051] Dual-redundant differential pressure detection unit: This unit is mainly used to collect the throttling differential pressure before and after the control valve. When selecting differential pressure measurement equipment, it is necessary to choose one that is compatible with the high-temperature operating conditions of the steam turbine, and to install it in a relatively stable flow field area at the inlet and outlet of the control valve. This avoids the impact of local flow field disturbances on measurement accuracy. Its sealing structure uses high-temperature resistant seals, and waterproof and dustproof treatment must be carried out at the wiring points.

[0052] The dual-redundant flow detection unit is mainly used to collect the flow rate of the main steam at the inlet of the regulating stage. It uses a flow measurement device suitable for high-temperature steam media and is installed in the straight section of the main steam pipeline. It is necessary to ensure that the measurement section is in the region of stable flow field in order to ensure that the flow data has high accuracy.

[0053] Regarding the temperature detection array, it is mainly used to collect the steam temperature at the nozzle outlet. Specifically, multiple temperature sensors are evenly arranged along the annular area of ​​the nozzle outlet, thus fully and completely capturing the temperature field distribution. Furthermore, the sensor leads are laid with heat-resistant protective tubing to effectively prevent damage from high-temperature environments.

[0054] The auxiliary parameter detection unit includes a series of detection devices for parameters such as unit speed, power generation, and reheat steam temperature. These devices are installed on the corresponding key parts of the unit to ensure that all auxiliary parameters can be collected comprehensively and reliably.

[0055] The control module, as the core of the system's decision-making process, integrates high-speed data processing capabilities, multi-model computation functions, and the ability to switch control modes to ensure real-time and accurate decision-making. Its specific configuration is as follows:

[0056] In terms of hardware configuration, an industrial-grade controller with high-speed data processing capabilities and high reliability was selected. The high-speed data acquisition unit and dedicated computing unit are integrated together, ensuring efficient operation during data processing and computation. The controller is installed in a well-ventilated control area, away from heat sources. It is also equipped with reliable heat dissipation devices and a grounding system to strongly guarantee the stable operation of the hardware.

[0057] Regarding the core algorithms and models, the data preprocessing algorithm works as follows: an outlier removal algorithm is used to filter out outliers in the collected data, and a smoothing filter algorithm is used to reduce measurement noise interference, thereby ensuring that the data input into the calculation model is stable and reliable.

[0058] Load factor calculation model: The load factor calculation model is constructed by integrating many parameters such as main steam flow, reheat steam temperature and throttling pressure difference. It is trained with a large amount of historical operating data to determine the weight of each parameter, so as to ensure that the load factor calculation results can accurately reflect the actual operating load of the unit.

[0059] Dynamic coefficient calculation model: A dynamic empirical coefficient model is constructed based on the load rate and load fluctuation characteristics. When the load fluctuation frequency exceeds the set threshold, a filtering optimization algorithm is activated to improve the accuracy of coefficient calculation.

[0060] Secondary correction logic: Reasonably set the correction step size and adjustment interval. If the preset adaptation requirements are still not met after the first correction, the secondary correction process will be automatically started to ensure the accuracy of nozzle area adaptation.

[0061] In terms of control modes, four control modes are preset: automatic correction mode, manual operation mode in emergency situations, remote operation and maintenance mode, and adaptive adjustment mode based on operating conditions. The mode can be switched automatically or manually according to the actual operating status of the generator set and the specific fault situation to meet the various needs proposed in different operating scenarios.

[0062] The execution module adopts a "primary and backup redundancy" design. Its core function is to accurately adjust the nozzle area according to the instructions output by the control module, thereby ensuring that the entire adjustment process is reliable and stable. The specific configuration is as follows:

[0063] For the main actuator, a drive unit with high-precision adjustment capabilities is selected, and it is rigidly connected to the nozzle adjustment linkage to ensure stable and accurate power transmission. For the hydraulic or pneumatic pipelines of the drive system, high-strength, high-pressure-resistant tubing is used, and reliable seals are selected to prevent media leakage.

[0064] The backup actuator is installed parallel to the main actuator, and its drive mechanism is complementary to that of the main actuator. This ensures a rapid switchover in case of a failure in the main actuator, allowing it to take over the adjustment tasks. The backup actuator's piping system is also equipped with a dedicated filtration device to prevent impurities from causing blockages and affecting the normal operation of the entire system.

[0065] Regarding the displacement feedback unit, a high-precision displacement detection device is installed at the location of the actuator output shaft to feed back the deviation between the actual stroke and the target stroke of the actuator in real time, thereby providing closed-loop feedback data to the control module.

[0066] The communication module enables real-time data interaction between various modules within the system and also interfaces with external monitoring systems to ensure real-time and reliable data transmission. Its specific configuration is as follows:

[0067] For internal communication units, industrial-grade high-speed bus technology is used to connect various modules such as detection, control, and execution. Matching resistors are configured at the bus terminals to optimize signal transmission quality. A dual-link redundancy design is also adopted. If the primary communication link fails, the system will automatically switch to the backup link to ensure uninterrupted internal data transmission.

[0068] Regarding external interface units, standardized communication interfaces must be configured to ensure smooth integration with the unit's central monitoring system, thereby supporting data uploading and the reception of remote control commands. Furthermore, remote control commands must undergo authorization verification before execution to guarantee system operational security. A reasonable data upload cycle must also be set to ensure the monitoring system can obtain real-time and effective information on unit operation and correct the system's actual status.

[0069] The intelligent monitoring and control module integrates multiple functions such as parameter monitoring, fault alarm, and remote control to achieve the purpose of monitoring and managing the entire process of the correction system. Specifically, it includes functions such as real-time presentation of operating parameters, issuing audible and visual alarms when a fault occurs, recording fault data, and remote parameter setting. It is also equipped with corresponding sensors and controllers to carry out real-time monitoring and control operations for the critical operating states of the system.

[0070] Sensor installation involves several aspects. When installing the differential pressure detection unit, ensure the pressure tap is located in a relatively stable flow field area at the inlet and outlet of the regulating valve. Flange connections must be tightened to the specified torque using a torque wrench, and high-temperature resistant sealant must be applied to the gaskets to enhance the sealing effect. The flow detection unit is installed on a straight section of the main steam pipeline; ensure the length of the preceding and following straight pipe sections meets measurement requirements. After installation, the pipe openings must be sealed, and a pressure test must be conducted to confirm the absence of leaks. The temperature detection array needs to be evenly distributed along the annular support at the nozzle outlet, ensuring the sensor insertion depth meets the requirements for sufficient contact with the steam. The protective tube and support must be sealed by welding. Auxiliary parameter sensors must be installed in designated locations according to the corresponding equipment installation specifications, ensuring secure installation without mechanical interference.

[0071] Sensor calibration involves using standard calibration equipment to perform multi-point calibration operations on each sensor. For differential pressure sensors, typical pressure points covering the measurement range are selected for calibration, and the deviation between the output value and the standard value is recorded, ensuring that this deviation is within the allowable range. For flow sensors, a flow standard device is used to calibrate at different flow points, adjusting various parameters to ensure the measurement deviation meets the corresponding requirements. For temperature sensors, a standard constant temperature bath is used to calibrate at different temperature points, ensuring that the measurement accuracy meets the specified standards. After all calibration work is completed, the obtained data is recorded for future maintenance reference.

[0072] In terms of hardware deployment, a level should be used to calibrate the control cabinet during installation to ensure it is placed horizontally. Grounding cables must be connected according to specifications to ensure grounding resistance meets relevant requirements. The installation direction of the cooling fans needs to be confirmed to ensure good heat dissipation, and they should be kept away from heat sources and strong electromagnetic interference sources. Cables connecting various modules should be laid according to signal type to avoid signal interference.

[0073] Program debugging involves several aspects: First, debugging the data preprocessing program involves simulating abnormal and fluctuating data inputs to verify the effectiveness of outlier removal and smoothing filtering. Second, the load rate and dynamic coefficient calculation model is debugged by inputting historical data obtained under different operating conditions to verify the consistency between the calculated results and the actual operating conditions. Third, the control mode switching program is debugged by simulating different faults and operating condition changes to verify the timeliness and reliability of mode switching. Throughout the debugging process, it is also necessary to record the parameters of each program during operation in detail and optimize the program performance based on these records.

[0074] The actuators are installed as follows: the main actuator and the backup actuator should be installed parallel to each other in the periphery of the nozzle adjusting rod, ensuring convenient installation for subsequent maintenance and avoiding mechanical interference. The actuators and adjusting rod are connected using a flexible coupling. After connection, a dial indicator is used to measure their coaxiality. If coaxiality deviation is found, it is corrected by adjusting the thickness of the shims to ensure compliance with requirements. When connecting hydraulic or pneumatic lines, double compression fittings are used, tightened to the specified torque. After all connections are completed, a pressure test is conducted to confirm the absence of leaks.

[0075] The commissioning process involves two aspects. First, it involves adjusting the accuracy of the actuator. Specifically, different target area commands are input, and the area value obtained after actual adjustment is recorded. Then, the deviation between this area value and the target value is calculated, and the deviation is controlled within an acceptable range by adjusting the drive parameters. Second, it involves commissioning the redundancy switching function. This simulates a scenario where the main actuator fails, verifying whether the backup mechanism can automatically complete the switchover within a specified time. During this switching process, fluctuations in the nozzle area and changes in the unit load are continuously monitored to ensure a smooth and undisturbed switching process.

[0076] Using a bus tester, tests were conducted on the internal communication links to continuously and for extended periods monitor the data transmission status, recording packet loss rate and transmission delay in detail. It was crucial to ensure that both packet loss rate and delay remained within pre-defined ranges. Debugging operations were performed on the external communication interfaces, and data interaction tests were conducted with the central monitoring system to verify the accuracy of data upload cycles and remote command reception and response. The access control function was also tested to ensure that only authorized personnel could perform remote control operations.

[0077] When the steam turbine is operating at low load, this system dynamically corrects the nozzle area. Compared to the traditional method of fixing the nozzle area, this significantly improves the opening of the regulating valve and reduces throttling losses. Verification through actual operation shows that under low load conditions, throttling losses can be reduced by 30% or more. When faced with load fluctuations, the system can complete the correction response within seconds, a response speed far exceeding the hourly response time of traditional manual correction, thus quickly meeting the peak-shaving needs of the power grid. In fault simulation tests, when sensors or actuators malfunction, the system can quickly switch to redundant equipment or emergency mode without shutdown, effectively improving the reliability of the unit during operation.

[0078] Automatic dynamic correction method for nozzle area of ​​turbine regulating stage

[0079] This method relies on the aforementioned system and includes many key steps, such as system initialization, data acquisition and preprocessing, load rate and dynamic coefficient calculation, and the determination of the optimal nozzle area, as well as the adjustment and secondary correction. Finally, there are monitoring and mode switching aspects. These six core steps together form a complete closed-loop correction process to ensure that the nozzle area can be continuously and accurately adapted to the unit's operating conditions.

[0080] S1: System Initialization

[0081] After the system starts, it first executes an initialization process to lay the foundation for subsequent correction work, which specifically includes:

[0082] Enter the rated design parameters of the steam turbine, such as the rated nozzle area, rated load, design main steam flow rate, and design reheat steam temperature. These key parameters should be entered as the basis for subsequent calculations.

[0083] Regarding the parameter weights for training the load factor calculation model, a large amount of historical operating data covering the units under different load conditions needs to be imported. Then, a data fitting algorithm is used to determine the weight coefficients corresponding to each parameter in the model, thereby ensuring the model's computational accuracy.

[0084] The system automatically performs self-checks, with the control module responsible for automatically detecting the communication status of each module and the operational status of key equipment. If all modules are in normal condition, the system will enter standby mode; however, if a fault is detected, the system will trigger an audible and visual alarm and display relevant information about the faulty module, thus facilitating appropriate troubleshooting by maintenance personnel.

[0085] S2: Data Acquisition and Preprocessing

[0086] The detection module collects various operating parameters in real time according to a pre-set high-frequency acquisition frequency, such as the throttling pressure difference of the regulating valve, the main steam flow rate, the nozzle outlet temperature, the unit speed, the power generation capacity, and the reheat steam temperature. After the acquisition is completed, the control module performs preprocessing operations on these data. First, it uses an outlier removal algorithm to filter out abnormal data that deviates significantly from the normal range. Then, it uses a smoothing filter algorithm to reduce noise in the data, thereby obtaining stable and reliable preprocessed data, which in turn provides high-quality input for subsequent calculations.

[0087] S3: Calculation of Load Factor and Dynamic Coefficient

[0088] The control module calls the load rate calculation model, inputting pre-processed data such as main steam flow rate, reheat steam temperature, and throttling pressure difference into the model to calculate the unit's current actual load rate. Next, based on the calculated load rate and the real-time monitored load fluctuation frequency, it calls the dynamic coefficient calculation model to determine the dynamic empirical coefficients under the current operating conditions. If the load fluctuation frequency exceeds a preset threshold, a filtering optimization algorithm is automatically activated to optimize the dynamic coefficients, thereby improving their accuracy.

[0089] S4: Optimal Nozzle Area Calculation and Verification

[0090] Based on the rated nozzle area, the calculated load rate, and dynamic empirical coefficients, a pre-defined optimal area calculation formula is used to solve for the optimal nozzle area under the current operating conditions. After the solution is completed, boundary verification is performed on the obtained optimal nozzle area to determine whether it falls within a pre-defined safety correction range (generally 0.8 to 1.2 times the rated nozzle area). If it is within this range, it is determined as the final target correction area; if it exceeds this range, the boundary value is used as the target correction area to ensure that the entire correction process can be carried out safely and reliably.

[0091] S5: Execution of Adjustments and Secondary Corrections

[0092] The control module sends instructions to the execution module regarding the target correction area. The main actuator drives the nozzle blade unfolding area adjustment operation according to the preset adjustment rate. The displacement feedback unit feeds back the actual stroke data of the actuator to the control module in real time. After the adjustment is completed, the control module uses the feedback data and the control valve opening data collected by the detection module to determine whether the preset adaptation requirements have been met (generally, the control valve opening should be greater than or equal to 70%). If the requirements are met, the correction is considered complete. If the requirements are not met, the secondary correction process is initiated. The dynamic empirical coefficient is fine-tuned according to the preset step size, and then the target correction area is recalculated and the corresponding adjustment operation is performed until the adaptation requirements are finally met.

[0093] S6: Monitoring and Mode Switching

[0094] The intelligent monitoring and control module monitors the operating status of each module in the system and the key operating parameters of the unit in real time. These parameters include the pressure of the actuator drive system, fluctuations in the main steam flow, and pipe wall thickness. Based on the acquired monitoring data, the module judges the unit's operating condition. If the current operating condition is stable and there are no faults, it remains in automatic correction mode. If a sensor or actuator malfunction is detected, it automatically switches to emergency manual mode, allowing maintenance personnel to manually input target areas for adjustment. If remote updates to model parameters or system maintenance are required, it can switch to remote maintenance mode. When the unit's load conditions change significantly, it automatically switches to adaptive mode, adjusting the correction cycle and accuracy parameters to adapt to the specific needs of different operating conditions.

[0095] Actual work process:

[0096] Module collaborative working principle:

[0097] The detection module acts as the data source in the system, its most crucial role being to provide accurate and continuous raw data for subsequent calculations. For extremely important parameters, a dual-redundant sensor configuration is employed, meaning that two sets of sensors simultaneously acquire data for the same parameter. The control module compares the deviations between the two sets of acquired data in real time. If the deviation exceeds a pre-set threshold, one set of sensors is considered faulty, and the system automatically switches to the data acquired by the other set, effectively preventing data acquisition interruptions. The sensor installation locations are optimized using flow field simulation to ensure that the acquired parameters accurately and objectively reflect the actual operating status of the unit. All sensors operate at a uniformly prescribed high-frequency acquisition frequency and transmit the acquired data synchronously to the control module via a communication module, preventing calculation errors caused by asynchronous data acquisition.

[0098] After receiving the preprocessed data from the detection module, the control module obtains the true load rate using a multi-parameter fusion load rate calculation model. Compared to the traditional method of calculating based on a single parameter, this effectively prevents interference from fluctuations in a single parameter, thus ensuring that the deviation in load rate calculation is kept within a relatively small range. The dynamic empirical coefficient model combines load rate and load fluctuation characteristics, using a sine function to simulate the impact of periodic load fluctuations on throttling losses. This allows the calculated target nozzle area to better match the requirements of actual operating conditions. The secondary correction logic addresses potential deviations during the primary correction process by using small-step fine-tuning to achieve accuracy compensation. This ensures that the final determined nozzle area allows the regulating valve opening to meet preset adaptation requirements, thereby effectively reducing throttling losses.

[0099] After receiving the target area command from the control module, the execution module drives the nozzle blades to make corresponding adjustments at a pre-set rate. This rate design balances correction efficiency and operational stability, preventing sudden changes in nozzle area due to excessively rapid adjustments, thus avoiding fluctuations in unit load. The displacement feedback unit collects the actuator's stroke data in real time, forming a closed-loop feedback system. Based on the feedback data, the control module adjusts the drive command in real time to ensure a certain level of accuracy. Furthermore, a primary and backup redundant execution mechanism is designed, providing dual protection. In the event of a failure in the primary mechanism, the backup mechanism can be automatically switched via pressure or status signals. During the switching process, the control module reduces the adjustment rate to further minimize area fluctuations, ultimately ensuring stable unit operation.

[0100] The communication module utilizes high-speed bus technology to achieve rapid data transmission between modules. It employs a dual-link redundancy design to ensure uninterrupted communication, providing a reliable data channel for collaborative module operation. The intelligent monitoring module aggregates operational data from all modules in real time, forming a global monitoring view. This allows maintenance personnel to intuitively grasp the system's operational status. The fault alarm function monitors threshold values ​​for key parameters. When these parameters exceed the set thresholds, it promptly issues warning signals and records relevant data before and after the fault, providing a basis for subsequent fault analysis. Remote maintenance functionality is achieved through standardized communication interfaces, overcoming geographical limitations and improving maintenance efficiency.

[0101] Dynamic correction core logic: the essence of reducing throttling losses

[0102] There is a negative correlation between the throttling loss of a steam turbine and the opening of the regulating valve. Under low-load conditions, the steam flow rate decreases. If the nozzle area remains constant, the regulating valve is prone to being excessively closed. Once the opening decreases, the throttling loss increases sharply. The core principle of the dynamic correction logic involved in this invention is to increase the regulating valve opening under the same steam flow rate by reducing the nozzle area in real time, thereby reducing the throttling loss. The specific logic flow is as follows:

[0103] Load sensing trigger: When the detection module detects that the unit load rate is lower than the set threshold, the control module determines that it has entered a low load condition and starts the dynamic correction process.

[0104] Accurately calculate the suitable area: The current load rate is calculated based on a multi-parameter fusion model. At the same time, the dynamic coefficient is determined by combining the load fluctuation characteristics. Then, relevant formulas are used to calculate the optimal nozzle area that matches the current working conditions, so as to ensure that the area can increase the opening of the regulating valve to within the range of efficient operation.

[0105] Smooth adjustment: The actuator adjusts the nozzle area according to a preset rate until the optimal value is reached, thus preventing flow fluctuations caused by sudden changes in area.

[0106] Fluctuation-adaptive optimization: When the load fluctuates, the dynamic coefficient will be adjusted in real time, which will lead to a fine adjustment of the optimal nozzle area to ensure that the opening of the regulating valve is always within a reasonable range, thereby ensuring that the throttling loss can be kept at a low level.

[0107] Redundancy guarantee principle: Reliability support for continuous operation

[0108] 1. Sensor redundancy protection

[0109] The system employs dual-redundant sensors for key parameters, and the control module includes fault diagnosis logic. This logic compares the data deviations and trends from the two sets of sensors to determine the fault condition. In the event of a fault, the system automatically disconnects the data channel of the faulty sensor and switches to the working sensor, recording the fault information and issuing an alarm. After the fault is resolved, the system can automatically or manually resume dual-redundant operation, ensuring continuous and reliable data acquisition.

[0110] 2. Redundancy guarantee of implementing agencies

[0111] The main and standby actuators operate independently. The control module monitors the operating status of the main actuator in real time, including parameters such as hydraulic pressure and drive current. If an abnormality is detected in the main actuator, the standby actuator will be immediately activated. Once activated, the control module will adjust the drive parameters and reduce the adjustment rate to ensure that the fluctuation of the nozzle area is kept within the allowable range of the unit during the switching process. After the main actuator completes its repair work, it can be manually switched back to the main actuator's operating state, at which point the standby actuator will return to standby mode.

[0112] 3. Control mode redundancy protection

[0113] Multiple control modes are preset to build redundancy, with the automatic correction mode being the normal operating mode. When the system detects sensor malfunctions, actuator abnormalities, or computing module failures, it automatically switches to emergency manual mode. In this mode, maintenance personnel can manually input target area commands to control the actuators, ensuring the unit does not shut down. An adaptive operating mode is designed based on different load fluctuation characteristics. By adjusting the correction cycle and accuracy parameters, it can adapt to different operating scenarios, thereby improving the system's adaptability.

[0114] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A dynamic automatic correction system for the nozzle area of ​​a steam turbine regulating stage, characterized in that, include: The detection module is used to collect the operating parameters of the turbine regulating stage in real time, including the pressure difference across the regulating valve, main steam flow, reheat steam temperature, unit power and speed. The control module is connected to the detection module and has a built-in load rate calculation model, dynamic correction algorithm and secondary correction logic. It is used to receive the data collected by the detection module and process it to calculate the actual load rate β, dynamic empirical coefficient C(β) and optimal nozzle correction area S, and output control commands. The execution module is communicatively connected to the control module and is used to receive the control commands and drive the nozzle blades to adjust to change the nozzle area. The execution module adopts a redundant configuration of main execution mechanism and backup execution mechanism. The communication module is used to establish a signal transmission link between the detection module, control module and execution module, and a communication interface with the unit's central monitoring system is reserved. The control module presets the nozzle area correction boundary as 0.8S0≤S≤1.2S0, where S is the original design nozzle area under rated operating conditions.

2. The turbine regulating stage nozzle area dynamic automatic correction system according to claim 1, characterized in that: The detection module includes: The dual-redundant differential pressure sensor for the control valve is a high-precision capacitive differential pressure transmitter with a measurement range of 0-2MPa and an accuracy of ±0.05%FS. It is installed on the flanges before and after the control valve. The high-temperature ultrasonic flow meter with dual redundancy configuration is a dual-channel insertion design and is installed on the main steam pipe at the inlet of the regulating stage. A K-type thermocouple array, consisting of 12 thermocouples, is evenly arranged circumferentially along the annular support at the nozzle outlet. The auxiliary sensor group includes a speed sensor, a power sensor, and a reheat steam temperature sensor.

3. The turbine regulating stage nozzle area dynamic automatic correction system according to claim 2, characterized in that: The control module includes an industrial-grade PLC or DCS controller, integrating a high-speed data acquisition card and a dedicated computing chip. The data sampling frequency is ≥100Hz, the signal transmission delay is ≤10ms, and the controller response time is ≤50ms. The dedicated computing chip pre-stores a data preprocessing program, uses the 3σ criterion to filter outliers, and performs noise reduction processing using a moving average algorithm.

4. The turbine regulating stage nozzle area dynamic automatic correction system according to claim 3, characterized in that: In the execution module, the main actuator is a hydraulic drive mechanism controlled by an electro-hydraulic servo valve, which adjusts the nozzle area resolution accordingly. The backup actuator is a pneumatic actuator, which is installed in parallel with the main actuator and automatically switches in case of failure.

5. The turbine regulating stage nozzle area dynamic automatic correction system according to claim 4, characterized in that: The communication module uses the Profinet bus to realize inter-module communication, and is configured with a ModbusTCP interface to interface with the central monitoring system of the unit, supporting data upload and remote parameter configuration.

6. A method for dynamic automatic correction of the nozzle area of ​​a turbine regulating stage, based on the dynamic automatic correction system and method for the nozzle area of ​​a turbine regulating stage as described in any one of claims 1-5, characterized in that: Includes the following steps: S1: System initialization, input the turbine rated parameters, including the original design nozzle area S0, rated load, design main steam flow rate G, design reheat steam temperature T, and regulating stage thermodynamic parameters. The weight coefficients k1, k2, and k3 of the load rate calculation model are determined by training with historical operating data of the unit. S2: The detection module collects operating parameters in real time and transmits them to the control module via the communication module. The control module performs outlier filtering and noise reduction preprocessing on the collected data through a preset program. S3: The control module calculates the actual load rate β through a multi-parameter load rate calculation model. The model is: β=k1·(Gactual / Gdesign)+k2·(Treheat / Tdesign)+k3·ΔPthrottle, where Gactual is the measured main steam flow rate, Treheat is the measured reheat steam temperature, and ΔPthrottle is the measured throttle pressure difference of the regulating valve. S4: The control module calculates the dynamic empirical coefficient C(β), and the calculation formula is: C(β)=1.1+0.05sin(πβ / 100). When the load fluctuation frequency is >0.5Hz, the adaptive filtering algorithm is enabled to optimize C(β). S5: The control module calculates the optimal nozzle correction area S according to the formula S=S0×(β / 100)×C(β), and verifies whether S is within the range of 0.8S0-1.2S0. If it exceeds the range, the corresponding boundary value is taken. S6: The control module sends a control command to the execution module, and the execution module drives the nozzle blades to adjust to the correction area S; S7: Detect the opening of the regulating valve after correction. If the opening is <70%, start the secondary correction logic: fine-tune C(β) by step size 0.02, with an interval of 2 seconds between each adjustment and recalculate S to perform the adjustment until the opening is ≥70% or the maximum number of adjustments is reached (10). S8: Adaptively switches control modes based on unit load fluctuations to achieve continuous dynamic correction of nozzle area.

7. The method for dynamic automatic correction of the nozzle area of ​​a steam turbine regulating stage according to claim 6, characterized in that: The control modes mentioned in step S8 include: Automatic correction mode is the default mode. It will be automatically activated when β < 85%. The correction cycle is 5 seconds when the load is stable and 1 second when the load fluctuates greatly. Emergency manual mode, activated when the sensor or actuator malfunctions, allows manual input of the target nozzle area within the range of 0.8S0-1.2S0, and the system will drive the adjustment. In the remote operation and maintenance mode, the central monitoring system allows for remote viewing of operational data, automatic start / stop correction functions, and updating of weight coefficients k1, k2, and k3. The adaptive operating mode automatically identifies stable low load (β=50%-75%), fluctuating low load (β fluctuation>±3% / min), or rated load (β≥85%), and adapts the accuracy correction, fast response, and stop correction strategies accordingly.

8. The method for dynamic automatic correction of the nozzle area of ​​a turbine regulating stage according to claim 6, characterized in that: In step S1, the weighting coefficients k1, k2, and k3 are determined through training with more than 1,000 sets of historical operating data of the unit, and the thermodynamic parameters of the regulating stage include a speed ratio of 0.3-0.45 and a reaction degree of 0.05-0.

15.

9. The method for dynamic automatic correction of the nozzle area of ​​a steam turbine regulating stage according to claim 6, characterized in that: In step S3, when any sensor fails, the system automatically switches to the redundant sensor to collect data. The switching transition time is ≤0.5s and the system records the running data for 5s before and after the failure time.

10. The method for dynamic automatic correction of the nozzle area of ​​a steam turbine regulating stage according to claim 6, characterized in that: In step S7, the nozzle blade adjustment stroke is monitored in real time during the secondary correction process. When the stroke deviation exceeds ±0.2mm, an actuator fault alarm is triggered.

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