A kind of main protection control system suitable for thermal power plant boiler

Abstract

The application provides a kind of main protection control system suitable for boiler of thermal power plant.A kind of main protection control system suitable for boiler of thermal power plant, comprising: redundant signal acquisition module, multimodal logic discrimination module, fault self-healing switching module, event recording wave tracing module, man-machine interaction early warning module and linkage execution module.The application provides a kind of main protection control system suitable for boiler of thermal power plant, by adopting three-to-two redundant signal acquisition architecture, cooperate signal filtering, synchronous calibration and logic voting technology, solve the problem of protection misoperation, refusal caused by single channel signal distortion, missing, effectively eliminate the abnormal signal deviating from true value, greatly improve the reliability of signal acquisition and logic discrimination, ensure the accuracy of protection system input data;By setting multimodal adaptive protection logic, the precise adaptation of boiler start-stop, steady-state, fault full operating condition operating scene is realized, and the defect that traditional single fixed logic cannot adapt to variable working condition is solved.

Description

Technical Field

[0001] This invention relates to the field of thermal power plant automation control technology, and in particular to a main protection control system for boilers in thermal power plants. Background Technology

[0002] As the core pressure-bearing and heat-exchange equipment in a thermal power generation system, the safe and stable operation of a boiler in a thermal power plant directly affects the power generation efficiency of the entire generator unit and the production safety of the plant. With the development of the power industry towards higher parameters and larger capacity, the boiler operating environment is becoming increasingly complex, and the requirements for the level of automation control are also increasing. The boiler main protection control system (FSSS furnace safety monitoring system) is the core device to ensure the safe operation of the boiler. It mainly undertakes key functions such as furnace anti-explosion, main fuel fault protection, pressure parameter over-limit protection, and equipment interlock protection. When the boiler experiences abnormal operating conditions, the system needs to promptly trigger protective actions such as main fuel trip (MFT) or equipment interlock shutdown to avoid major safety accidents such as furnace explosion, boiler overpressure, and dry burning due to water shortage. It is a key research focus in the field of power plant thermal control.

[0003] The existing improved scheme employs dual-channel redundant acquisition technology. This scheme configures two independent acquisition channels for the same monitoring parameter, and judges the signal quality by comparing the difference between the two signals. When the two signals are consistent, the average value is taken as the valid input; when the deviation between the two signals is too large, it is judged as a channel fault and an alarm is issued. This dual-channel scheme solves the signal interruption problem caused by single-point failure to a certain extent and improves the fault tolerance of the system. However, this scheme still has obvious logical defects when facing complex operating conditions. When both signals are affected by the same source of interference or common-mode faults occur, the comparison logic may fail and cannot eliminate abnormal signals. More importantly... Yes, existing systems generally use a single, fixed protection logic, which cannot adapt to the different operating conditions of boilers during start-up and shutdown, steady-state operation, and fault / abnormal operation. During boiler start-up and shutdown, fuel input and air volume regulation fluctuate drastically, and parameter oscillation is normal. If the stringent thresholds used during steady-state operation are applied, false protection is easily triggered. Under fault conditions, if the logic response is delayed, it is impossible to stop the spread of the accident in time. In addition, existing systems lack a complete fault tracing mechanism, often only recording simple action events and failing to retain full-dimensional waveform data before and after protection triggering. This makes it difficult for maintenance personnel to accurately locate the root cause of the fault, which is not conducive to system optimization and iteration.

[0004] In summary, existing main protection and control systems for thermal power plant boilers suffer from technical problems such as insufficient reliability of signal acquisition, poor adaptability to operating conditions, weak fault tolerance and self-healing capabilities, and difficulty in tracing fault sources. How to improve the accuracy of signal acquisition and logic judgment while ensuring the safe operation of boilers, and achieve adaptive protection and rapid fault self-healing under all operating conditions, has become a technical challenge that urgently needs to be solved by those skilled in the art.

[0005] Therefore, it is necessary to provide a solution to the above-mentioned technical problems for the main protection control system of boilers in thermal power plants. Summary of the Invention

[0006] This invention provides a main protection control system for boilers in thermal power plants, which solves the problem of how to improve the accuracy of signal acquisition and logic judgment while ensuring the safe operation of the boiler, and achieve adaptive protection under all operating conditions and rapid self-healing of faults.

[0007] To solve the above-mentioned technical problems, the present invention provides a main protection control system for boilers in thermal power plants, comprising: a redundant signal acquisition module, a multi-modal logic discrimination module, a fault self-healing switching module, an event recording and tracing module, a human-machine interaction early warning module, and a linkage execution module;

[0008] The redundant signal acquisition module is used to perform multi-channel independent acquisition and signal optimization processing of boiler operating parameters;

[0009] The multimodal logic discrimination module is connected to the redundant signal acquisition module and is used to switch the corresponding protection logic criteria according to the real-time operating conditions of the boiler.

[0010] The fault self-healing switching module is connected to the redundant signal acquisition module and the multimodal logic discrimination module, and is used to monitor the channel status and automatically perform isolation and switching operations when a fault is detected.

[0011] The event recording and tracing module is used to continuously record and store full-dimensional operating condition data before and after the protection action is triggered;

[0012] The human-computer interaction early warning module is used to realize the visual monitoring of the operating status and the display of hierarchical early warning information;

[0013] The linkage execution module is connected to the multimodal logic discrimination module and is used to execute graded protection actions based on the discrimination results;

[0014] The redundant signal acquisition module uses a two-out-of-three voting mechanism to verify the acquired signals and outputs valid data after eliminating abnormal signals; the multi-modal logic discrimination module has built-in start-stop mode, steady-state mode and fault mode, and automatically adapts the corresponding protection threshold and discrimination logic according to the boiler operation stage.

[0015] Preferably, the redundant signal acquisition module includes: three independent signal acquisition channels, a signal preprocessing unit, and a logic voting unit; the three independent signal acquisition channels are used to acquire the same boiler operating parameters respectively; the signal preprocessing unit is connected to each of the signal acquisition channels respectively, and is used to filter and synchronize the acquired raw signals; the logic voting unit is connected to the signal preprocessing unit, and is used to receive the three preprocessed signals, compare the values ​​of each signal with a preset deviation range, eliminate abnormal signals that exceed the deviation range, and use the average value of the remaining valid signals as the final output value.

[0016] Preferably, the multimodal logic discrimination module includes: an operating condition identification unit, a logic configuration unit, and a dynamic loading unit; the operating condition identification unit is used to identify the current operating condition based on the boiler main fuel trip status, unit load rate, and key parameter change rate, and generate a mode switching command; the logic configuration unit stores multiple sets of protection logic criteria corresponding to the start-stop mode, steady-state mode, and fault mode, respectively, and the protection logic criteria include at least differentiated action thresholds and delay settings; the dynamic loading unit is used to respond to the mode switching command and load the protection logic criteria corresponding to the current operating condition into the real-time discrimination loop.

[0017] Preferably, the fault self-healing switching module includes: a fault monitoring unit, a decision logic unit, and an execution switching unit; the fault monitoring unit is used to monitor the signal quality of each signal acquisition channel in real time, the signal quality including signal disconnection, signal over-range, and signal noise level; the decision logic unit is used to generate a fault isolation command and a backup channel activation command when a fault occurs in any signal acquisition channel; the execution switching unit is used to disconnect the faulty channel in response to the fault isolation command and connect a preset backup channel to maintain continuous system operation.

[0018] Preferably, the linkage execution module is configured with hierarchical protection linkage logic, which divides protection actions into three levels:

[0019] The first level is an early warning prompt. When the monitored parameters exceed the limit but do not reach the danger threshold, an audible and visual alarm is triggered and the event is recorded.

[0020] The second level is secondary protection, which triggers auxiliary equipment to adjust or reduce load when the monitored parameters reach the dangerous threshold but there is a possibility of recovery;

[0021] The third level is emergency tripping, which triggers the cutting off of fuel supply and shutdown when the monitored parameters reach the limit threshold or the main fuel tripping conditions are met.

[0022] Preferably, the event recording and tracing module includes: a data caching unit, a trigger recording unit, and a tracing analysis unit; the data caching unit is used to cache the original acquisition data and intermediate process data for a preset duration in a circular queue; the trigger recording unit is used to lock the current cached data and transfer the data within a preset time period before and after the protection action to a permanent storage file when the protection action is triggered; the tracing analysis unit is used to read the permanent storage file and reproduce the parameter change process when the protection action occurs in the form of waveform playback.

[0023] Preferably, the human-computer interaction early warning module includes a visualization display unit, a hierarchical early warning unit, and a manual intervention interface.

[0024] Preferably, the visualization display unit is used to display the boiler operating parameter curves, the currently activated protection mode, and the working status of each acquisition channel in real time; the graded early warning unit is used to output early warning signals according to the severity of the fault by color differentiation or flashing frequency variation; and the manual intervention interface is used to receive either a mode forced switching command or a protection reset command input by the operator.

[0025] Preferably, the signal preprocessing unit performs filtering processing on the acquired signal, including:

[0026] Random interference is eliminated by using a moving average filtering algorithm;

[0027] A first-order hysteresis filtering algorithm is used to suppress high-frequency noise.

[0028] Preferably, the synchronization calibration includes compensating for the transmission delay of the three acquired signals to ensure that the signals input to the logic voting unit are aligned in timing.

[0029] Compared with related technologies, the main protection control system for boilers in thermal power plants provided by this invention has the following advantages:

[0030] This invention provides a main protection control system for boilers in thermal power plants. By employing a three-out-of-two redundant signal acquisition architecture, coupled with signal filtering, synchronous calibration, and logic voting technology, it completely solves the problems of false tripping and failure to trip caused by single-channel signal distortion and missing signals. It effectively eliminates abnormal signals deviating from the true value, significantly improving the reliability of signal acquisition and logic judgment, and ensuring the accuracy of input data to the protection system. Through the setting of multi-modal adaptive protection logic, it achieves precise adaptation to all operating scenarios of boiler start-up, shutdown, steady state, and fault conditions. Based on the differences in boiler thermodynamic characteristics under different operating conditions, it dynamically adjusts the protection threshold and delay setpoint, overcoming the shortcomings of traditional single fixed logic that cannot adapt to changing operating conditions. This avoids false tripping caused by drastic parameter fluctuations during start-up and shutdown, and ensures the timeliness and effectiveness of protection actions under fault conditions. The system has a modular structure, high integration, and clearly defined and collaborative functional units, adapting to various pulverized coal and oil-fired power plant boilers with strong compatibility. This provides a convenient and efficient solution for the retrofitting of main protection systems in old thermal power units and for supporting new units, and has broad application prospects. Attached Figure Description

[0031] Figure 1 This invention provides a structural schematic diagram of a main protection control system for boilers in thermal power plants.

[0032] Figure 2 for Figure 1 The diagram shows a redundant signal acquisition module.

[0033] Figure 3 for Figure 1 The diagram shows a module diagram of the multimodal logic discrimination module.

[0034] Figure 4 for Figure 1 The diagram shows a self-healing switching module.

[0035] Figure 5 for Figure 1 The diagram shows the module schematic of the event recording and tracing module;

[0036] Figure 6 for Figure 1 The diagram shows a schematic of the human-computer interaction early warning module. Detailed Implementation

[0037] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0038] Please refer to the following: Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 and Figure 6 ,in, Figure 1 This invention provides a structural schematic diagram of a main protection control system for boilers in thermal power plants. Figure 2 for Figure 1 The diagram shows a redundant signal acquisition module. Figure 3 for Figure 1 The diagram shows a module diagram of the multimodal logic discrimination module. Figure 4 for Figure 1 The diagram shows a self-healing switching module. Figure 5 for Figure 1 The diagram shows the module schematic of the event recording and tracing module; Figure 6 for Figure 1 The diagram shows a schematic of the human-computer interaction early warning module.

[0039] A main protection control system for boilers in thermal power plants includes: a redundant signal acquisition module, a multi-modal logic discrimination module, a fault self-healing switching module, an event recording and tracing module, a human-machine interaction early warning module, and a linkage execution module.

[0040] The redundant signal acquisition module is used to perform multi-channel independent acquisition and signal optimization processing of boiler operating parameters;

[0041] The multimodal logic discrimination module is connected to the redundant signal acquisition module and is used to switch the corresponding protection logic criteria according to the real-time operating conditions of the boiler.

[0042] The fault self-healing switching module is connected to the redundant signal acquisition module and the multimodal logic discrimination module, and is used to monitor the channel status and automatically perform isolation and switching operations when a fault is detected.

[0043] The event recording and tracing module is used to continuously record and store full-dimensional operating condition data before and after the protection action is triggered;

[0044] The human-computer interaction early warning module is used to realize the visual monitoring of the operating status and the display of hierarchical early warning information;

[0045] The linkage execution module is connected to the multimodal logic discrimination module and is used to execute graded protection actions based on the discrimination results;

[0046] The redundant signal acquisition module uses a two-out-of-three voting mechanism to verify the acquired signals and outputs valid data after eliminating abnormal signals; the multi-modal logic discrimination module has built-in start-stop mode, steady-state mode and fault mode, and automatically adapts the corresponding protection threshold and discrimination logic according to the boiler operation stage.

[0047] The redundant signal acquisition module includes three independent signal acquisition channels, a signal preprocessing unit, and a logic voting unit. The three independent signal acquisition channels are used to acquire the same boiler operating parameters. The signal preprocessing unit is connected to each of the signal acquisition channels and is used to filter and synchronize the acquired raw signals. The logic voting unit is connected to the signal preprocessing unit and is used to receive the three preprocessed signals, compare the values ​​of each signal with a preset deviation range, eliminate abnormal signals that exceed the deviation range, and use the average value of the remaining valid signals as the final output value.

[0048] The multimodal logic discrimination module includes: an operating condition identification unit, a logic configuration unit, and a dynamic loading unit. The operating condition identification unit is used to identify the current operating condition based on the boiler main fuel trip status, unit load rate, and key parameter change rate, and generate a mode switching command. The logic configuration unit stores multiple sets of protection logic criteria corresponding to the start-up mode, steady-state mode, and fault mode, respectively. The protection logic criteria include at least differentiated action thresholds and delay settings. The dynamic loading unit is used to respond to the mode switching command and load the protection logic criteria corresponding to the current operating condition into the real-time discrimination loop.

[0049] The fault self-healing switching module includes a fault monitoring unit, a decision logic unit, and an execution switching unit. The fault monitoring unit is used to monitor the signal quality of each signal acquisition channel in real time. The signal quality includes signal disconnection, signal over-range, and signal noise level. The decision logic unit is used to generate a fault isolation command and a backup channel activation command when a fault occurs in any signal acquisition channel. The execution switching unit is used to disconnect the faulty channel in response to the fault isolation command and connect the preset backup channel to maintain continuous system operation.

[0050] The linkage execution module is configured with hierarchical protection linkage logic, which divides protection actions into three levels:

[0051] The first level is an early warning prompt. When the monitored parameters exceed the limit but do not reach the danger threshold, an audible and visual alarm is triggered and the event is recorded.

[0052] The second level is secondary protection, which triggers auxiliary equipment to adjust or reduce load when the monitored parameters reach the dangerous threshold but there is a possibility of recovery;

[0053] The third level is emergency tripping, which triggers the cutting off of fuel supply and shutdown when the monitored parameters reach the limit threshold or the main fuel tripping conditions are met.

[0054] The event recording and tracing module includes a data caching unit, a trigger recording unit, and a tracing analysis unit. The data caching unit is used to cache the original acquisition data and intermediate process data for a preset duration in a circular queue. The trigger recording unit is used to lock the current cached data and transfer the data within a preset time period before and after the protection action to a permanent storage file when the protection action is triggered. The tracing analysis unit is used to read the permanent storage file and reproduce the parameter change process when the protection action occurs in the form of waveform playback.

[0055] The human-computer interaction early warning module includes a visualization display unit, a hierarchical early warning unit, and a manual intervention interface.

[0056] The visualization display unit is used to display the boiler operating parameter curves, the currently activated protection mode, and the working status of each acquisition channel in real time. The graded early warning unit is used to output early warning signals according to the severity of the fault, either by color differentiation or by changing the flashing frequency. The manual intervention interface is used to receive either the mode forced switching command or the protection reset command input by the operator.

[0057] The signal preprocessing unit performs filtering processing on the acquired signal, including:

[0058] Random interference is eliminated by using a moving average filtering algorithm;

[0059] A first-order hysteresis filtering algorithm is used to suppress high-frequency noise.

[0060] The synchronous calibration includes compensating for the transmission delay of the three acquired signals to ensure that the signals input to the logic voting unit are aligned in timing.

[0061] The redundant signal acquisition module, as the perception layer of the system, is deployed between the sensor network and the control cabinet at the boiler site. It is responsible for multi-channel independent acquisition and signal optimization processing of core operating parameters such as furnace pressure, steam drum water level, and main steam flow. Its output is connected to the input of the multi-modal logic discrimination module via industrial Ethernet or fieldbus.

[0062] The multimodal logic discrimination module, as the decision-making core of the system, receives processed real-time data, identifies the current operating condition of the boiler based on the built-in intelligent algorithm, and automatically calls the corresponding protection logic criteria for calculation. The calculation results are transmitted to the fault self-healing switching module and the linkage execution module respectively.

[0063] The fault self-healing switching module monitors the health status of the redundant signal acquisition module in real time. Once an abnormality is detected, the self-healing mechanism is immediately triggered, and the signal acquisition channel is switched via hard wiring or fiber optic signal control.

[0064] The event recording and tracing module connects to each module via a high-speed data bus, capturing and storing full-process data in real time. The human-machine interaction early warning module provides maintenance personnel with a visual monitoring interface and operation interface through a display terminal and input devices.

[0065] The linkage execution module outputs control commands to the boiler's actuators (such as fuel shut-off valves, blowers, etc.) to complete the final protection action. The working logic of the entire system is as follows: First, the redundant signal acquisition module obtains high-reliability field data. Then, the multi-modal logic discrimination module selects an appropriate protection strategy based on the operating conditions. The fault self-healing switching module ensures the reliability of the hardware level throughout the process. Once the discrimination result meets the action conditions, the linkage execution module implements hierarchical protection. All process data is completely retained by the event recording and tracing module.

[0066] The signal acquisition channel is used to acquire the same boiler operating parameters. Taking furnace pressure acquisition as an example, in this embodiment, three independent pressure transmitters (Rosemount 3051 series can be selected) are installed at different measuring points on the same cross section of the furnace. The signal output lines of the three transmitters are connected to three independent I / O card channels in the control cabinet through three independent shielded cables. This completely isolated physical design ensures that when the sensor of any channel fails, the cable is damaged, or the I / O card is damaged, the other two channels can still work independently, avoiding the occurrence of common mode failure.

[0067] The signal preprocessing unit is connected to each signal acquisition channel. In terms of hardware circuitry, the signal preprocessing unit uses a high-precision operational amplifier to construct a signal conditioning circuit, which amplifies and filters the acquired raw analog signals. In terms of software algorithm, the signal preprocessing unit performs a moving average filtering algorithm and a synchronization calibration operation. Specifically, the moving average filtering algorithm takes N=10 sampling points and performs an arithmetic average of 10 consecutively acquired data points to eliminate random interference signals. The synchronization calibration compensates for the millisecond-level delay differences caused by different transmission paths by timestamping the three signals, ensuring that the three signals input to the subsequent logic voting unit are strictly aligned in timing.

[0068] The logic voting unit is the core of signal processing. It adopts a 2 out of 3 (2oo3) voting logic. The unit has a preset signal deviation threshold. For example, for the furnace pressure signal, the deviation threshold is set to ±200Pa. The logic voting unit compares the values ​​of the three signals in real time. If the difference between each pair of the three signals is within the deviation threshold range, the three signals are determined to be valid, and the arithmetic mean of the three signals is taken as the final output value. If the difference between one signal and the other two exceeds the threshold, the signal is determined to be abnormal and is removed. The average of the remaining two valid signals is taken as the output. If the difference between the three signals exceeds the limit, it is determined to be a serious fault. The preset safety value (such as the rated operating value) is output and a system-level alarm is triggered. This mechanism completely solves the problem of false operation caused by single-channel signal distortion.

[0069] The operating condition identification unit is used to sense the boiler's operating status in real time. It has a pre-built operating condition identification algorithm, with the following specific criteria:

[0070] (1) Start-up and shutdown modes: When a boiler main fuel trip (MFT) reset signal is detected, the total fuel quantity is less than 10% of the rated value, and the turbine speed increases, it is determined to be the start-up stage; when a unit disconnection signal or a main fuel trip signal is detected, it is determined to be the shutdown stage. Under the start-up and shutdown modes, the boiler parameters fluctuate drastically;

[0071] (2) Steady-state mode: When the unit load rate is detected to fluctuate between 30% and 100%, and the rate of change of the main parameters (such as main steam pressure and temperature) is less than the set threshold (such as pressure change rate < 0.5 MPa / min), it is determined to be in the steady-state operation stage;

[0072] (3) Fault mode: When any key parameter (such as furnace pressure, steam drum water level) is detected to be close to the warning threshold (such as reaching 90% of the warning value), or when the redundant signal acquisition module 1 reports a channel failure, it is determined to be a fault abnormal stage.

[0073] The logic configuration unit stores three independent sets of protection logic criteria. Taking furnace pressure protection as an example:

[0074] (1) Start-stop mode criteria: The action threshold is set to ±3000Pa (relaxed threshold), and the action delay is set to 5 seconds. By relaxing the threshold and extending the delay, pressure fluctuations caused by deflagration or purging in the early stage of boiler ignition are tolerated, and false tripping is prevented.

[0075] (2) Steady-state modal criteria: The action threshold is set to ±2000Pa (standard threshold), and the action delay is set to 2 seconds. Strict criteria are adopted during steady-state operation to ensure timely response to minor leaks or anomalies.

[0076] (3) Fault mode criteria: The action threshold is set to ±2000Pa, the action delay is shortened to 1 second, and auxiliary criteria (such as flame detection signal interlock) are automatically activated to improve the sensitivity of protection actions.

[0077] The dynamic loading unit receives the mode switching command issued by the operating condition identification unit and uses pointer mapping or dynamic link library technology to load the criterion parameters corresponding to the current operating condition into the real-time calculation loop in milliseconds, thereby achieving seamless switching of protection strategies.

[0078] The fault monitoring unit monitors the signal quality of each signal acquisition channel in real time, and the monitoring dimensions include:

[0079] (1) Signal disconnection monitoring: Determine whether a disconnection has occurred by detecting whether the current in the detection loop is below 4mA (for Type II instruments) or whether the voltage is 0V;

[0080] (2) Signal over-range monitoring: Determine whether the acquired value exceeds the sensor's range (e.g., pressure transmitter output current >20mA or <4mA).

[0081] (3) Signal noise level monitoring: Calculate the variance of the high-frequency components of the signal. If the variance exceeds the preset noise threshold, the signal is judged to be severely interfered with.

[0082] The decision logic unit 32 has built-in fault decision logic. When any signal acquisition channel 11 is determined to be faulty, the unit immediately generates a fault isolation command. If the system is configured with a backup channel (such as the backup channel in a four-out-of-two architecture), an activation command is generated synchronously.

[0083] The execution switching unit physically disconnects the faulty channel from the back-end processing circuit by controlling the relay array or electronic switch chip (such as ADG series analog switches), preventing abnormal voltage in the faulty channel from damaging the downstream circuit. At the same time, it connects the backup channel. For a three-out-of-two system, if only a single channel fault occurs, the system automatically degrades to a two-out-of-one mode to continue operating without shutdown for maintenance, thus achieving safety assurance under "operating with faults".

[0084] The event recording and tracing module provides a "black box" function for accident analysis. The data caching unit uses a large-capacity dynamic random access memory (DRAM) to build a circular buffer. The default caching duration is set to 30 seconds before the protection action is triggered and 60 seconds after the trigger. The data content covers the original waveforms, intermediate calculated values, switch status and communication messages between modules of all acquisition channels.

[0085] The trigger recording unit is configured with a variety of trigger conditions, including: protection action output (MFT action), warning signal trigger, manual trigger, etc. Once a trigger condition is detected, the unit immediately locks the data pointer of the current buffer area and transfers the data in the circular buffer to a permanent file in non-volatile memory (such as SD card or solid-state drive). The file format adopts the standard COMTRADE format, which is easy for general waveform analysis software to read.

[0086] The source analysis unit is deployed on the human-machine interface terminal, providing waveform playback, zoom, measurement and spectrum analysis functions. Maintenance personnel can retrieve historical waveform files and play back the parameter change curves before and after the fault occurred millisecond by millisecond to accurately locate whether the protection action was caused by sensor failure, actual over-limit, or external interference.

[0087] The visualization display unit adopts an industrial-grade touch screen and develops a monitoring interface through configuration software. The main screen of the interface displays the boiler's process flow diagram in real time, and dynamically displays the current values, units, and status (normal / warning / fault) at key measuring points. A modal status indicator bar is set at the bottom of the screen, which uses different colors to indicate the current system mode of "start-up / shutdown", "steady state" or "fault".

[0088] The graded early warning unit divides the early warning information into three levels based on the severity of the fault: Level 1 warning (yellow flashing) indicates that the parameter is close to the threshold; Level 2 warning (orange flashing) indicates that the channel is faulty or the parameter exceeds the limit but has not reached the trip value; Level 3 alarm (red flashing + buzzer) indicates that the protection action has been triggered, and maintenance personnel can quickly identify the system status.

[0089] The manual intervention interface provides operation permission management. Operators with engineer privileges can use this interface to force switch system modes (such as forcibly entering start-stop mode during special tests) or reset isolated fault channels. All manual intervention operations are logged by the system.

[0090] The linkage execution module is responsible for executing the final protection instructions. Its core lies in the hierarchical protection linkage logic, which divides the protection actions into three levels:

[0091] Level 1 (Early Warning): When the monitored parameter slightly exceeds the limit (such as reaching 90% of the early warning threshold), the linkage execution module only outputs an audible and visual alarm signal to the human-machine interaction early warning module, without triggering equipment action, giving maintenance personnel a time window to adjust the operating parameters.

[0092] Level 2 (Secondary Protection): When the monitored parameters reach the danger threshold but do not reach the trip value, or when a key auxiliary device malfunctions, the linkage execution module outputs instructions to the auxiliary device. For example, when the furnace pressure rises abnormally, it automatically triggers the adjustment of the induced draft fan guide vane opening or automatically reduces the coal feeder speed, so as to bring the parameters back to the normal range through active adjustment and avoid direct tripping.

[0093] Level 3 (Emergency Trip): When the monitored parameters reach the limit threshold (such as furnace pressure reaching +3000Pa for 2 seconds), or when the MFT main fuel trip condition is met, the linkage execution module immediately outputs a passive dry contact signal to the trip solenoid valve of the boiler fuel supply system, cuts off all fuel input, and links to close the blower and induced draft fan dampers to implement an emergency shutdown and ensure equipment safety.

[0094] Example 1: Retrofitting the main protection system of a 300MW coal-fired power unit boiler

[0095] This embodiment is applied to a 300MW subcritical coal-fired unit in a power plant, with boiler model DG1025 / 18.2-II4. The system configuration is as follows:

[0096] The redundant signal acquisition module is configured with 3 independent furnace pressure acquisition channels. The sensor range is -4000Pa to +4000Pa, with an accuracy of 0.075%. The sampling frequency of the signal preprocessing unit is set to 100Hz, and the moving average filter window is N=10.

[0097] In the multimodal logic discrimination module, the furnace pressure high trip threshold under start-stop mode is set to +1700Pa (the original value is +1700Pa, but this system relaxes it to +2000Pa in start-stop mode to adapt to ignition fluctuations), with a delay of 3 seconds; under steady-state mode, it is maintained at +1700Pa, with a delay of 2 seconds.

[0098] The fault self-healing switching module is configured with a fourth backup pressure transmitter channel. When any working channel fails, the switching unit automatically switches to the backup channel, with a switching time of less than 50ms.

[0099] The operational results show that during the unit startup phase, due to frequent furnace pressure fluctuations in the initial ignition stage, the original system experienced two false trips. After the modification, the system automatically identified the start-up and shutdown modes, relaxed the protection thresholds, and successfully avoided false trips, increasing the unit startup success rate to 100%. During steady-state operation, the system automatically switched to steady-state mode, ensuring highly sensitive safety monitoring.

[0100] Example 2: Waste Heat Boiler Protection in Gas-Steam Combined Cycle Units

[0101] This embodiment is applied to the waste heat boiler of a 9F-class gas-steam combined cycle unit. Due to the frequent start-up and shutdown of the gas turbine unit and the rapid load change rate, the response speed of the protection system is required to be extremely high.

[0102] In this embodiment, the operating condition identification unit of the multimodal logic discrimination module has added a "rapid load change" sub-mode. When the unit load change rate is detected to be greater than 10% of the rated load / minute, the system automatically enters this sub-mode and dynamically adjusts the threshold compensation coefficient of the steam drum water level protection to offset the influence of false water levels.

[0103] The linkage execution module has enabled secondary protection logic. When the water level in the steam drum reaches the high second value (+150mm), it automatically triggers the emergency drain valve to open, thus preventing the water level from continuing to rise to the high third value (+200mm) and causing the MFT action.

[0104] Operational data shows that after implementing the system, the number of unplanned shutdowns caused by water level fluctuations has decreased by 80%, greatly improving the unit's peak-shaving capacity and economy.

[0105] The threshold, delay time, and other parameters mentioned in the embodiments of this invention are only illustrative of preferred embodiments. In actual applications, they can be adjusted according to the specific boiler model, capacity, and fuel characteristics. For example, for supercritical units, the parameter thresholds need to be recalibrated according to their higher operating pressure and temperature. The communication between the modules of the system can adopt various industrial communication protocols such as Modbus TCP, OPC UA, or IEC 61850 to adapt to the interface requirements of different power plant DCS systems. In addition, in addition to the three-out-of-two logic, the algorithm of the logic voting unit can also be extended to four-out-of-two or dual-channel two-out-of-two logic in situations with extremely high reliability requirements. The core idea of ​​all of them is to eliminate abnormal signals through redundant voting, which all fall within the protection scope of this invention.

[0106] The working principle of the main protection control system for thermal power plant boilers provided by this invention is as follows:

[0107] During operation, the system first synchronously acquires the same boiler operating parameters through three independent acquisition channels. The acquired signals are then filtered and synchronously calibrated to ensure the quality of the source data. A three-out-of-two voting mechanism is used to perform logical verification on the three processed signals, eliminating abnormal signals and outputting valid monitoring values ​​to improve data reliability. The system identifies the current operating condition of the boiler and automatically switches to the corresponding protection logic criteria in start-up, steady-state, and fault modes to achieve adaptive operation. The system monitors the status of the acquisition channels in real time, and when a single point of failure is detected, it automatically isolates the faulty channel and switches to the backup channel to achieve system self-healing.

[0108] Based on the current protection logic criteria, the effective monitoring values ​​are judged to exceed the limit. According to the judgment result, the graded protection actions are executed. The graded protection actions include early warning prompts, secondary protection and emergency tripping. When the protection action is triggered, the full-dimensional operating condition data within the preset time period before and after the action is automatically locked and stored to form a traceable waveform file for easy post-event analysis.

[0109] Compared with related technologies, the main protection control system for boilers in thermal power plants provided by this invention has the following advantages:

[0110] This invention provides a main protection control system for boilers in thermal power plants. By employing a three-out-of-two redundant signal acquisition architecture, coupled with signal filtering, synchronous calibration, and logic voting technology, it completely solves the problems of false tripping and failure to trip caused by single-channel signal distortion and missing signals. It effectively eliminates abnormal signals deviating from the true value, significantly improving the reliability of signal acquisition and logic judgment, and ensuring the accuracy of input data to the protection system. Through the setting of multi-modal adaptive protection logic, it achieves precise adaptation to all operating scenarios of boiler start-up, shutdown, steady state, and fault conditions. Based on the differences in boiler thermodynamic characteristics under different operating conditions, it dynamically adjusts the protection threshold and delay setpoint, overcoming the shortcomings of traditional single fixed logic that cannot adapt to changing operating conditions. This avoids false tripping caused by drastic parameter fluctuations during start-up and shutdown, and ensures the timeliness and effectiveness of protection actions under fault conditions. The system has a modular structure, high integration, and clearly defined and collaborative functional units, adapting to various pulverized coal and oil-fired power plant boilers with strong compatibility. This provides a convenient and efficient solution for the retrofitting of main protection systems in old thermal power units and for supporting new units, and has broad application prospects.

[0111] This invention achieves self-healing repair without shutdown by monitoring channel signal quality in real time, automatically identifying and isolating single-point fault channels and interference signals, and activating backup channels. This greatly improves the continuous operation capability of the system, significantly reduces the probability of unplanned unit shutdowns, and reduces the economic losses caused by power plant shutdowns.

[0112] This invention, through a full-process event recording and tracing module, can completely retain all-dimensional operating condition data before and after the protection action is triggered, and supports waveform playback and precise tracing, providing detailed data support for fault analysis, greatly reducing the difficulty of operation and maintenance, shortening the fault diagnosis time, and improving the efficiency of system iteration and optimization.

[0113] This invention employs a tiered linkage protection mechanism, matching different protection actions such as early warning, load reduction, and emergency tripping according to the severity of the fault. This avoids minor abnormalities directly triggering emergency shutdowns, effectively improving the power generation economy and operational stability of the unit while ensuring boiler operation safety and reducing unnecessary equipment wear and tear.

[0114] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A main protection control system for boilers in thermal power plants, characterized in that, include: Redundant signal acquisition module, multimodal logic discrimination module, fault self-healing switching module, event recording and tracing module, human-machine interaction early warning module and linkage execution module; The redundant signal acquisition module is used to perform multi-channel independent acquisition and signal optimization processing of boiler operating parameters; The multimodal logic discrimination module is connected to the redundant signal acquisition module and is used to switch the corresponding protection logic criteria according to the real-time operating conditions of the boiler. The fault self-healing switching module is connected to the redundant signal acquisition module and the multimodal logic discrimination module, and is used to monitor the channel status and automatically perform isolation and switching operations when a fault is detected. The event recording and tracing module is used to continuously record and store full-dimensional operating condition data before and after the protection action is triggered; The human-computer interaction early warning module is used to realize the visual monitoring of the operating status and the display of hierarchical early warning information; The linkage execution module is connected to the multimodal logic discrimination module and is used to execute graded protection actions based on the discrimination results; The redundant signal acquisition module uses a two-out-of-three voting mechanism to verify the acquired signals and outputs valid data after eliminating abnormal signals; the multi-modal logic discrimination module has built-in start-stop mode, steady-state mode and fault mode, and automatically adapts the corresponding protection threshold and discrimination logic according to the boiler operation stage.

2. The main protection control system for boilers in thermal power plants according to claim 1, characterized in that, The redundant signal acquisition module includes three independent signal acquisition channels, a signal preprocessing unit, and a logic voting unit. The three independent signal acquisition channels are used to acquire the same boiler operating parameters. The signal preprocessing unit is connected to each of the signal acquisition channels and is used to filter and synchronize the acquired raw signals. The logic voting unit is connected to the signal preprocessing unit and is used to receive the three preprocessed signals, compare the values ​​of each signal with a preset deviation range, eliminate abnormal signals that exceed the deviation range, and use the average value of the remaining valid signals as the final output value.

3. The main protection control system for boilers in thermal power plants according to claim 1, characterized in that, The multimodal logic discrimination module includes: an operating condition identification unit, a logic configuration unit, and a dynamic loading unit. The operating condition identification unit is used to identify the current operating condition based on the boiler main fuel trip status, unit load rate, and key parameter change rate, and generate a mode switching command. The logic configuration unit stores multiple sets of protection logic criteria corresponding to the start-up mode, steady-state mode, and fault mode, respectively. The protection logic criteria include at least differentiated action thresholds and delay settings. The dynamic loading unit is used to respond to the mode switching command and load the protection logic criteria corresponding to the current operating condition into the real-time discrimination loop.

4. A main protection control system for boilers in thermal power plants according to claim 1, characterized in that, The fault self-healing switching module includes a fault monitoring unit, a decision logic unit, and an execution switching unit. The fault monitoring unit is used to monitor the signal quality of each signal acquisition channel in real time. The signal quality includes signal disconnection, signal over-range, and signal noise level. The decision logic unit is used to generate a fault isolation command and a backup channel activation command when a fault occurs in any signal acquisition channel. The execution switching unit is used to disconnect the faulty channel in response to the fault isolation command and connect the preset backup channel to maintain continuous system operation.

5. A main protection control system for boilers in thermal power plants according to claim 1, characterized in that, The linkage execution module is configured with hierarchical protection linkage logic, which divides protection actions into three levels: The first level is an early warning prompt. When the monitored parameters exceed the limit but do not reach the danger threshold, an audible and visual alarm is triggered and the event is recorded. The second level is secondary protection, which triggers auxiliary equipment to adjust or reduce load when the monitored parameters reach the dangerous threshold but there is a possibility of recovery; The third level is emergency tripping, which triggers the cutting off of fuel supply and shutdown when the monitored parameters reach the limit threshold or the main fuel tripping conditions are met.

6. A main protection control system for boilers in thermal power plants according to claim 1, characterized in that, The event recording and tracing module includes a data caching unit, a trigger recording unit, and a tracing analysis unit. The data caching unit is used to cache the original acquisition data and intermediate process data for a preset duration in a circular queue. The trigger recording unit is used to lock the current cached data and transfer the data within a preset time period before and after the protection action to a permanent storage file when the protection action is triggered. The tracing analysis unit is used to read the permanent storage file and reproduce the parameter change process when the protection action occurs in the form of waveform playback.

7. A main protection control system for boilers in thermal power plants according to claim 1, characterized in that, The human-computer interaction early warning module includes a visualization display unit, a hierarchical early warning unit, and a manual intervention interface.

8. A main protection control system for boilers in thermal power plants according to claim 7, characterized in that, The visualization display unit is used to display the boiler operating parameter curves, the currently activated protection mode, and the working status of each acquisition channel in real time. The graded early warning unit is used to output early warning signals according to the severity of the fault, either by color differentiation or by changing the flashing frequency. The manual intervention interface is used to receive either the mode forced switching command or the protection reset command input by the operator.

9. A main protection control system for boilers in thermal power plants according to claim 2, characterized in that, The signal preprocessing unit performs filtering processing on the acquired signal, including: Random interference is eliminated by using a moving average filtering algorithm; A first-order hysteresis filtering algorithm is used to suppress high-frequency noise.

10. A main protection control system for boilers in thermal power plants according to claim 9, characterized in that, The synchronous calibration includes compensating for the transmission delay of the three acquired signals to ensure that the signals input to the logic voting unit are aligned in timing.

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