A device and method for extending the function of electrical accident protection tripping of a generator unit

Abstract

The application provides a kind of generating and variable group electrical accident protection tripping function extension device and method, belong to the security technical field of thermal power plant, device includes: generating and variable group electrical accident protection detection module;DCS control module is connected with generating and variable group electrical accident protection detection module communication, DCS control module includes logic control unit, self-adapting delay unit, rotating speed threshold correction unit and signal filtering and credibility verification unit;Execution module is electrically connected with DCS control module, and execution module includes EH oil pump control unit, boiler control unit, valve control unit and vacuum pump control unit;State detection module is connected with DCS control module communication, and state detection module includes turbine tripping signal detection unit, TSI rotating speed detection unit, generating and variable group main switch state detection unit, operating condition parameter acquisition unit.The application provides reliable, efficient accident overspeed pre-control scheme for thermal power unit, guarantees the safe and stable operation of unit.

Description

Technical Field

[0001] This invention belongs to the field of thermal power plant safety technology, specifically relating to an extended device and method for the tripping function of electrical fault protection in generator-transformer units. Background Technology

[0002] With the rapid development of new energy sources, the frequency regulation task of thermal power units is becoming increasingly heavy. The risks of equipment aging and boiler oxide scale formation are intensifying, leading to frequent occurrences of valve mis-closing or failure to close properly when the turbine trips due to valve jamming, control system failures, etc., which in turn can trigger main engine accidents such as overspeeding and hydrogen explosions.

[0003] In large thermal power units, when the electrical fault protection of the generator-transformer unit activates, both the generator and the turbine must trip simultaneously to quickly isolate the fault. However, the opening time of the main electrical switch is much faster than the closing time of the steam valves, and residual steam can still drive the turbine to accelerate. In existing technologies, after such a trip, the determination of whether to take overspeed prevention measures relies on fixed delays and fixed speed thresholds, which cannot adapt to the differences in operating conditions caused by real-time load changes, main steam pressure variations, and valve aging. Furthermore, the original TSI speed signal is easily interfered with, and historical steam valve closing data is not effectively utilized, leading to insufficient accuracy in judgment and a high risk of false or failed protection activation. More critically, the speed increases rapidly within seconds after the electrical fault protection activates, and traditional manual overspeed prevention measures, including stopping the EH oil pump and disrupting the vacuum, have a delayed response and cannot intervene in time. Previously, there was a case where a 1000MW unit experienced a hydrogen explosion and unit failure due to valve jamming after the electrical fault protection activated, causing the speed to exceed 3800rpm within seconds.

[0004] Therefore, it is urgent to optimize the judgment logic and signal processing methods by collecting key parameters such as real-time unit load, main steam pressure, and historical steam valve closing time, expand the tripping function of generator-transformer unit electrical fault protection, realize operating condition adaptation, signal credibility verification and rapid intervention, and pre-control the risk of generator-transformer unit overspeed and hydrogen explosion. Summary of the Invention

[0005] The purpose of this invention is to provide an extended device and method for the tripping function of electrical fault protection for generator-transformer units, in order to solve the problems of poor adaptability to operating conditions, insufficient accuracy of judgment, and inability to intervene in a timely manner in the prior art, which leads to overspeed and hydrogen explosion.

[0006] In a first aspect, embodiments of this application provide an extended device for the tripping function of electrical fault protection in a generator-transformer unit, the device comprising: The generator-transformer unit electrical fault protection detection module is used to monitor the operation status of the generator-transformer unit's electrical fault protection in real time. The electrical fault protection operations include differential protection, stator grounding protection, inter-turn short circuit protection, and heavy gas protection. The DCS control module is connected to the generator-transformer group electrical fault protection and detection module. The DCS control module includes a logic control unit, an adaptive delay unit, a speed threshold correction unit, and a signal filtering and reliability verification unit. The logic control unit is connected to the adaptive delay unit, the speed threshold correction unit, and the signal filtering and reliability verification unit, respectively. An execution module is connected to the DCS control module. The execution module includes an EH oil pump control unit, a boiler control unit, a valve control unit, and a vacuum pump control unit. The EH oil pump control unit, boiler control unit, valve control unit, and vacuum pump control unit are each connected to a logic control unit. A status detection module is connected to the DCS control module. The status detection module includes a turbine trip signal detection unit, a TSI speed detection unit, a generator-transformer main switch status detection unit, and an operating condition parameter acquisition unit. The turbine trip signal detection unit and the generator-transformer main switch status detection unit are respectively connected to the logic control unit. The TSI speed detection unit is connected to the signal filtering and reliability verification unit. The operating condition parameter acquisition unit is used to collect real-time load, main steam pressure, and historical steam valve closing time data of the unit. The operating condition parameter acquisition unit is connected to the adaptive delay unit.

[0007] Furthermore, the logic control unit is used to trigger the EH oil pump control unit to completely stop the EH oil pump without delay when the generator-transformer group electrical fault protection detection module detects any electrical fault protection action, and at the same time trigger a regular tripping action, the regular tripping action including: generator-transformer group main switch tripping, excitation switch tripping, turbine ETS tripping, and switching of plant auxiliary power.

[0008] Furthermore, the adaptive delay unit is used to calculate the redundant delay value by weighted averaging based on the historical valve closing time data collected by the operating condition parameter acquisition unit, and to calculate the total delay of the turbine trip signal. The total delay is equal to the sum of the maximum historical valve closing time and the redundant delay value.

[0009] Furthermore, the speed threshold correction unit is used to perform linear correction based on the reference speed increase value of 3180 rpm during the period from the generator fully shedding its rated load to the normal closing of the turbine valves, combined with real-time load and main steam pressure parameters. The correction formula is as follows:

[0010] in, K 1 represents the load correction factor, with a value ranging from 0.002. rpm / MW -0.005 rpm / MW , K 2 is the main steam pressure correction factor, with a value range of 1. rpm / MPa -3 rpm / MPaThe corrected speed threshold is no less than 3150 rpm and no more than 3250 rpm.

[0011] Furthermore, the signal filtering and reliability verification unit is used to process the speed signal collected by the TSI speed detection unit using a moving average filter to obtain the speed value. The filter window length is set to 5-10 sampling periods. The reliability of the signal is judged by the signal fluctuation amplitude of m consecutive sampling periods. When the fluctuation amplitude is ≤5 rpm, it is determined to be a reliable signal; otherwise, it is determined to be an interference signal and signal calibration is triggered. The formula for calculating the rotational speed is:

[0012] in, For the first n The filtered rotational speed value after each sampling period. The length of the filter window. For the first what The original rotational speed value for each sampling period.

[0013] Furthermore, in the execution module: The EH oil pump control unit is used for synchronous shutdown control of the EH oil pump in the unit; The boiler control unit trips the boiler by triggering the main fuel trip (MFT). The valve control unit uses an independent electromagnetic drive module for the rapid opening of boiler PCV valves, condenser vacuum breaker valves, and high and low pressure bypasses.

[0014] Furthermore, the DCS control module is also equipped with a manual intervention unit. When the logic control unit, adaptive delay unit, speed threshold correction unit, and signal filtering and reliability verification unit malfunction, the various actions of the execution module can be triggered manually.

[0015] Secondly, embodiments of the present invention also provide a method for tripping electrical fault protection of a generator-transformer unit, the method comprising the following steps: S1. The generator-transformer unit electrical fault protection detection module monitors the electrical fault protection status of the generator-transformer unit. The operating condition parameter acquisition unit continuously collects the real-time load, main steam pressure and historical steam valve closing time of the unit. The status detection module collects the turbine trip signal, the original TSI speed signal and the status of the generator-transformer unit main switch. S2. When any electrical fault protection action is detected, the DCS control module triggers the EH oil pump control unit to completely stop all EH oil pumps; triggers the main switch of the generator-transformer unit to trip, the excitation switch to trip, the turbine ETS to trip, and switches the plant auxiliary power. After the turbine trips, the boiler is tripped in conjunction. S3. The adaptive delay unit determines the total delay based on the historical steam valve closing time; the speed threshold correction unit calculates the corrected speed threshold based on the real-time load and main steam pressure of the unit; the signal filtering and credibility verification unit performs moving average filtering on the original TSI speed signal to obtain a credible speed signal. S4. The logic control unit of the DCS control module determines whether the following four conditions are met simultaneously: the electrical fault protection action has continued for the total delay obtained in step S3, no turbine trip signal has been received, the reliable speed signal is ≥ the corrected speed threshold, and the generator-transformer group main switch is in the open position. S5. If the four conditions are met, the DCS control module triggers the boiler to trip, opens the boiler PCV valve, opens the condenser vacuum breaker valve, opens the high and low pressure bypass, and completely stops the vacuum pump; if the four conditions are not met simultaneously, the execution state of step S2 is maintained, and the process returns to step S1, and steps S3-S4 are repeated until the four conditions are met.

[0016] Furthermore, the specific steps of step S3 are as follows: S31. The adaptive delay unit calculates the redundant delay value by weighted averaging based on historical valve closing time data, and calculates the total delay of the turbine trip signal. The total delay is equal to the sum of the maximum historical valve closing time and the redundant delay value. S32. The speed threshold correction unit calculates the corrected speed threshold based on real-time load and main steam pressure parameters using a linear correction formula; the correction formula is:

[0017] in, K 1 represents the load correction factor, with a value ranging from 0.002. rpm / MW -0.005 rpm / MW , K 2 is the main steam pressure correction factor, with a value range of 1. rpm / MPa -3 rpm / MPa The corrected speed threshold is no less than 3150 rpm and no more than 3250 rpm; S33. The signal filtering and reliability verification unit performs a moving average filter on the original TSI speed signal to obtain the speed value, and simultaneously verifies the reliability of the speed value. If it is an interference signal, calibration is triggered until a reliable speed signal is obtained; the calculation formula for the speed value is:

[0018] in, For the first n The filtered rotational speed value after each sampling period. The length of the filter window. For the first what The original rotational speed value for each sampling period.

[0019] Furthermore, in step S2, the method further includes the following steps: When the logic control unit, adaptive delay unit, speed threshold correction unit, and signal filtering and reliability verification unit malfunction, the various actions of the execution module are triggered manually.

[0020] As can be seen from the above technical solutions, the present invention has the following advantages: After an electrical fault protection action, the EH oil pump is completely shut down without delay, promoting valve closure. Subsequently, when conditions are met, boiler tripping and valve opening are automatically triggered, replacing manual operations that require minute-level response. This addresses the risk of speed spikes within seconds and avoids consequences such as hydrogen explosions and runaway axle breakage due to untimely intervention. The total delay is determined by an adaptive delay unit combined with historical valve closing times, and the speed threshold correction unit adjusts the threshold based on real-time load and main steam pressure, ensuring safety redundancy under high-parameter conditions while avoiding protection malfunctions under normal conditions. The signal filtering and reliability verification module filters out interference from the original speed signal, ensuring reliable speed data. Combined with multi-condition judgment, it avoids misjudgments caused by signal distortion, identifies valve loosening conditions, and improves judgment accuracy. It is compatible with the boiler-turbine-electric interlock without requiring significant equipment modifications, enhancing safety protection while reducing implementation difficulty. It provides a reliable and efficient accident overspeed pre-control scheme for thermal power units, ensuring the safe and stable operation of the unit. Attached Figure Description

[0021] To more clearly illustrate the technical solution of the present invention, the accompanying drawings used in the description will be briefly introduced below. Obviously, the accompanying 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.

[0022] Figure 1 This is a schematic diagram of the extended device for the electrical fault protection tripping function of the generator-transformer unit according to the present invention.

[0023] Figure 2 This is a flowchart illustrating the tripping method for electrical fault protection of generator-transformer units according to the present invention. Detailed Implementation

[0024] Taking a typical 2×600MW supercritical steam turbine generator unit in a thermal power plant as an example, the steam turbine is a single-stage reheat, three-cylinder, four-exhaust, single-shaft, dual-backpressure, condensing type. Both high- and medium-pressure main steam turbines have two main steam valves and four high-pressure regulating valves, with a rated speed of 3000 r / min. The generator uses a water-hydrogen-hydrogen cooling system, a unit-based wiring system, and no outlet switch. It is connected to the 220kV bus via the main transformer. The excitation system is a self-excited microprocessor-based digital thyristor rectifier system. Each unit has two high-pressure transformers; the two units share two start-up and standby transformers. The generator-transformer group protection has three cabinets, encompassing all protection functions for the generator, main transformer, excitation transformer, and high-pressure transformer. Cabinets A and B are two identical sets of main and backup electrical protection for the generator-transformer unit, including programmed reverse power and reverse power protection. Cabinet C is equipped with non-electrical quantity protection, including thermal protection (when the turbine trips, the signal is simultaneously sent to cabinet C to trip the generator without delay). Reverse power protection includes two types: programmed reverse power and reverse power protection. Normal programmed reverse power protection acts before reverse power protection. Programmed reverse power protection settings (criteria): DCS determines that both high-pressure main steam valves or both medium-pressure main steam valves are fully closed, AST bus pressure is low (out of three), active power -6MW, time delay 1s; Reverse power protection settings: active power -15MW; time delay 60s.

[0025] Large generators are mostly hydrogen-cooled units, and their overspeed accidents can cause severe vibrations, torsional vibrations, and even catastrophic consequences such as runaway engines, shaft breakage, and hydrogen explosions. Except for electrical protection actions and load shedding tests, it is strictly forbidden to disconnect the generator under load. When shutting down the unit, the generator's active and reactive power should first be reduced to zero. After confirming that the active power is zero and the energy meter has stopped or reversed, the generator should be disconnected from the system; alternatively, the turbine can be manually tripped or the boiler can be manually tripped to trip the turbine, and then the generator can be disconnected through the reverse power protection action. The main purpose of this is to pre-control overspeed accidents of the main unit. Therefore, after a turbine or boiler side trip or manual trip, the unit is generally shut down by the reverse power protection action. At this time, if the turbine valve is not tight or not closed (for example, valve jamming caused by oxide scale or fouling), the generator may fail to shut down. In cases where the boiler trips due to malfunctions in the DEH control system's solenoid valves or unloading valves, resulting in the inability of steam valves to close, and the reverse power protection fails to operate, operators can immediately stop the EH oil pump, disrupt the condenser vacuum, manually pull the boiler PCV valve, open the high and low pressure bypasses, and stop the vacuum pump after confirming a return to reverse power, thus preventing overspeed. Additionally, if the generator-transformer unit's electrical abnormality protection (such as overload, negative sequence overcurrent, or overexcitation protection) activates, it will only trip the turbine without disconnecting the generator. This also allows time to take similar measures should a steam valve not be tightly closed.

[0026] The various embodiments of the present invention will be described more fully in the following detailed description of the extended device and method for tripping the electrical fault protection of generator-transformer units. The present invention may have various embodiments, and adjustments and changes may be made therein. However, it should be understood that there is no intention to limit the various embodiments of the present invention to the specific embodiments disclosed herein, but rather the present invention should be understood to cover all adjustments, equivalents, and / or alternatives falling within the spirit and scope of the various embodiments of the present invention.

[0027] It should be understood that, when used in this specification, the term "comprising" indicates the presence of the described feature, integral, step, operation, element, and / or component, but does not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or collections thereof. The terms "comprising," "including," "having," and variations thereof all mean "including but not limited to," unless otherwise specifically emphasized.

[0028] The terms "one embodiment" or "some embodiments" used in this application mean that one or more embodiments of this application include the specific features, structures, or characteristics described in that embodiment. Therefore, the phrases "in one embodiment," "in some embodiments," "in other embodiments," "in still other embodiments," etc., appearing in different parts of this application do not necessarily refer to the same embodiment, but rather mean "one or more, but not all, embodiments," unless otherwise specifically emphasized.

[0029] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the specific embodiments. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0030] Please see Figure 1 The diagram shown is a schematic of a generator-transformer unit electrical fault protection tripping function extension device in a specific embodiment. The device includes: The generator-transformer unit electrical fault protection detection module is used to monitor the operation status of the generator-transformer unit's electrical fault protection in real time. The electrical fault protection operations include differential protection, stator grounding protection, inter-turn short circuit protection, and heavy gas protection. The DCS control module is connected to the generator-transformer group electrical fault protection and detection module. The DCS control module includes a logic control unit, an adaptive delay unit, a speed threshold correction unit, and a signal filtering and reliability verification unit. The logic control unit is connected to the adaptive delay unit, the speed threshold correction unit, and the signal filtering and reliability verification unit, respectively. An execution module is connected to the DCS control module. The execution module includes an EH oil pump control unit, a boiler control unit, a valve control unit, and a vacuum pump control unit. The EH oil pump control unit, boiler control unit, valve control unit, and vacuum pump control unit are each connected to a logic control unit. A status detection module is connected to the DCS control module. The status detection module includes a turbine trip signal detection unit, a TSI speed detection unit, a generator-transformer main switch status detection unit, and an operating condition parameter acquisition unit. The turbine trip signal detection unit and the generator-transformer main switch status detection unit are respectively connected to the logic control unit. The TSI speed detection unit is connected to the signal filtering and reliability verification unit. The operating condition parameter acquisition unit is used to collect real-time load, main steam pressure, and historical steam valve closing time data of the unit. The operating condition parameter acquisition unit is connected to the adaptive delay unit.

[0031] Furthermore, as a refinement and extension of the specific implementation of the above embodiments, in order to fully illustrate the specific implementation process of this embodiment, another generator-transformer group electrical fault protection tripping function extension device is provided, the device comprising: The generator-transformer unit electrical fault protection detection module is used to monitor the operation status of the generator-transformer unit's electrical fault protection in real time. The electrical fault protection operations include differential protection, stator grounding protection, inter-turn short circuit protection, and heavy gas protection. The DCS control module is connected to the generator-transformer group electrical fault protection and detection module. The DCS control module includes a logic control unit, an adaptive delay unit, a speed threshold correction unit, and a signal filtering and reliability verification unit. The logic control unit is connected to the adaptive delay unit, the speed threshold correction unit, and the signal filtering and reliability verification unit, respectively. An execution module is connected to the DCS control module. The execution module includes an EH oil pump control unit, a boiler control unit, a valve control unit, and a vacuum pump control unit. The EH oil pump control unit, boiler control unit, valve control unit, and vacuum pump control unit are each connected to a logic control unit. A status detection module is connected to the DCS control module. The status detection module includes a turbine trip signal detection unit, a TSI speed detection unit, a generator-transformer main switch status detection unit, and an operating condition parameter acquisition unit. The turbine trip signal detection unit and the generator-transformer main switch status detection unit are respectively connected to the logic control unit. The TSI speed detection unit is connected to the signal filtering and reliability verification unit. The operating condition parameter acquisition unit is used to collect real-time load, main steam pressure, and historical steam valve closing time data of the unit. The operating condition parameter acquisition unit is connected to the adaptive delay unit.

[0032] In some embodiments, the logic control unit is used to trigger the EH oil pump control unit to completely stop the EH oil pump without delay when the generator-transformer group electrical fault protection detection module detects any electrical fault protection action, and at the same time trigger a regular tripping action, the regular tripping action including: generator-transformer group main switch tripping, excitation switch tripping, turbine ETS tripping, and switching of plant auxiliary power.

[0033] In some embodiments, the adaptive delay unit is used to calculate the redundant delay value by weighted averaging based on the historical valve closing time data collected by the operating condition parameter acquisition unit, and to calculate the total delay of the turbine trip signal, wherein the total delay is equal to the sum of the maximum historical valve closing time and the redundant delay value.

[0034] In some embodiments, the speed threshold correction unit is used to perform linear correction based on a reference speed increase of 3180 rpm during the period from the generator fully shedding its rated load to the normal closing of the turbine valves, combined with real-time load and main steam pressure parameters. The correction formula is as follows:

[0035] in, K 1 represents the load correction factor, with a value ranging from 0.002. rpm / MW -0.005 rpm / MW , K 2 is the main steam pressure correction factor, with a value range of 1. rpm / MPa -3 rpm / MPa The corrected speed threshold is no less than 3150 rpm and no more than 3250 rpm.

[0036] In some embodiments, the signal filtering and reliability verification unit is used to process the speed signal collected by the TSI speed detection unit using a moving average filter to obtain the speed value. The filter window length is set to 5-10 sampling periods. The reliability of the signal is judged by the signal fluctuation amplitude of m consecutive sampling periods. When the fluctuation amplitude is ≤5 rpm, it is determined to be a reliable signal. Otherwise, it is determined to be an interference signal and signal calibration is triggered. The formula for calculating the rotational speed is:

[0037] in, For the first n The filtered rotational speed value after each sampling period. The length of the filter window. For the first what The original rotational speed value for each sampling period.

[0038] In some embodiments, in the execution module: The EH oil pump control unit is used for synchronous shutdown control of the EH oil pump in the unit; The boiler control unit trips the boiler by triggering the main fuel trip (MFT). The valve control unit uses an independent electromagnetic drive module for the rapid opening of boiler PCV valves, condenser vacuum breaker valves, and high and low pressure bypasses.

[0039] In some embodiments, the DCS control module is further configured with a manual intervention unit, which can manually trigger various actions of the execution module when the logic control unit, adaptive delay unit, speed threshold correction unit, and signal filtering and reliability verification unit malfunction.

[0040] Please see Figure 2 The diagram shown is a flowchart illustrating a method for tripping the electrical fault protection of a generator-transformer unit in a specific embodiment. The method includes: S1. The generator-transformer unit electrical fault protection detection module monitors the electrical fault protection status of the generator-transformer unit. The operating condition parameter acquisition unit continuously collects the real-time load, main steam pressure and historical steam valve closing time of the unit. The status detection module collects the turbine trip signal, the original TSI speed signal and the status of the generator-transformer unit main switch. In some embodiments, it is applied to a 2×600MW supercritical steam turbine generator set in a power plant. The generator of this unit adopts a water-hydrogen-hydrogen cooling method, with a rated speed of 3000r / min. The generator-transformer protection includes three cabinets, A, B, and C, covering electrical fault protection functions such as differential protection, stator grounding protection, inter-turn short circuit protection, and heavy gas protection. In this embodiment, the generator-transformer unit electrical fault protection detection module is connected to the electrical fault protection action signal circuits of the generator-transformer unit's A, B, and C cabinets to monitor the action status of various electrical fault protections such as differential protection and stator grounding protection in real time. The operating condition parameter acquisition unit continuously collects the unit's real-time load (acquisition frequency 10Hz), main steam pressure (acquisition accuracy ±0.01MPa), and historical steam valve closing time data for the past 6 months (including the measured closing times of each high-pressure main steam valve and medium-pressure main steam valve) through the unit's DCS data acquisition interface. In the status detection module, the turbine trip signal detection unit is connected to the turbine ETS trip signal circuit, the TSI speed detection unit uses the unit's original TSI system speed sensor (measurement range 0-4000r / min, accuracy ±1r / min) to collect the raw speed signal, and the generator-transformer unit main switch status detection unit obtains the opening and closing status signal through the main switch auxiliary contacts.

[0041] Under normal operating conditions of 300MW load and 16.7MPa main steam pressure, the generator-transformer unit's electrical fault protection detection module continuously monitors the status of various electrical protections. The operating condition parameter acquisition unit synchronously records real-time load and main steam pressure data and updates the historical steam valve closing time dataset (the maximum steam valve closing time in the last 3 months is 0.28s). The status detection module provides real-time feedback on the status information that the turbine has not tripped, the main switch is closed, and the original TSI speed is stable at 3000r / min.

[0042] S2. When any electrical fault protection action is detected, the DCS control module triggers the EH oil pump control unit to completely stop all EH oil pumps; triggers the main switch of the generator-transformer unit to trip, the excitation switch to trip, the turbine ETS to trip, and switches the plant auxiliary power. After the turbine trips, the boiler is tripped in conjunction. In step S2, the method further includes the following steps: When the logic control unit, adaptive delay unit, speed threshold correction unit, and signal filtering and reliability verification unit malfunction, the various actions of the execution module are triggered manually.

[0043] In some embodiments, when the generator stator grounding protection is activated (electrical fault protection activation triggered), the generator-transformer unit electrical fault protection detection module immediately transmits the activation signal to the DCS control module.

[0044] After receiving the signal, the DCS control module quickly triggers the EH oil pump control unit, cutting off the power supply circuits of the three EH oil pumps without delay, achieving synchronous shutdown of all EH oil pumps and rapidly reducing the safety oil pressure to facilitate valve closure. Simultaneously, it triggers the conventional trip sequence: sending trip commands to the generator-transformer main switch and excitation switch, which open within 25ms, disconnecting the generator from the system and excitation system; sending a trip signal to the turbine ETS system, de-energizing the AST solenoid valve to depressurize the unloading valve, triggering the turbine ETS trip; and switching the plant power load from the high-voltage plant transformer to the standby transformer via the plant power switching circuit to ensure stable plant power supply. According to the unit's large-scale interlocking logic, after the turbine ETS trips, it triggers the boiler MFT action, cutting off the boiler's main fuel supply and achieving boiler tripping.

[0045] During this process, the DCS control module performs real-time self-checks on the operating status of core algorithm units such as the logic control unit and the adaptive delay unit. If an abnormal data calculation is detected in the speed threshold correction unit (such as correction coefficient overflow), the DCS control system immediately issues an audible and visual alarm to prompt the operator to intervene. After confirming the abnormality through the control panel, the operator can trigger the backup control loop via the manual control panel: manually press the EH oil pump emergency stop button to confirm the complete shutdown of the EH oil pump, manually trip the generator transformer main switch and excitation switch using the manual trip switch, operate the turbine ETS manual trip knob, complete the switch from plant power to the standby transformer using the plant power manual switch, and finally manually trigger the boiler MFT action to ensure that all safety measures are implemented in place and to prevent accidents, overspeed, and hydrogen explosion risks that may be caused by improperly controlled steam valves.

[0046] S3. The adaptive delay unit determines the total delay based on the historical steam valve closing time; the speed threshold correction unit calculates the corrected speed threshold based on the real-time load and main steam pressure of the unit; the signal filtering and credibility verification unit performs moving average filtering on the original TSI speed signal to obtain a credible speed signal. The specific steps of step S3 are as follows: S31. The adaptive delay unit calculates the redundant delay value by weighted averaging based on historical valve closing time data, and calculates the total delay of the turbine trip signal. The total delay is equal to the sum of the maximum historical valve closing time and the redundant delay value. S32. The speed threshold correction unit calculates the corrected speed threshold based on real-time load and main steam pressure parameters using a linear correction formula; the correction formula is:

[0047] in, K 1 represents the load correction factor, with a value ranging from 0.002. rpm / MW -0.005 rpm / MW ,K 2 is the main steam pressure correction factor, with a value range of 1. rpm / MPa -3 rpm / MPa The corrected speed threshold is no less than 3150 rpm and no more than 3250 rpm; S33. The signal filtering and reliability verification unit performs a moving average filter on the original TSI speed signal to obtain the speed value, and simultaneously verifies the reliability of the speed value. If it is an interference signal, calibration is triggered until a reliable speed signal is obtained; the calculation formula for the speed value is:

[0048] in, For the first n The filtered rotational speed value after each sampling period. The length of the filter window. For the first what The original rotational speed value for each sampling period.

[0049] S4. The logic control unit of the DCS control module determines whether the following four conditions are met simultaneously: the electrical fault protection action has continued for the total delay obtained in step S3, no turbine trip signal has been received, the reliable speed signal is ≥ the corrected speed threshold, and the generator-transformer group main switch is in the open position. In some embodiments, the adaptive delay unit calculates a total delay of 0.35s based on the historical valve closing times of the past 6 months (with a weight of 0.6 for the most recent 3 months); the speed threshold correction unit calculates a corrected speed threshold of 3190rpm by combining the real-time load of 320MW and the main steam pressure of 18.1MPa; and the signal filtering unit obtains a reliable speed signal by performing a moving average filter (window length of 8 sampling periods).

[0050] When the generator differential protection trips, the DCS control module initiates S4 judgment: First, it confirms that the protection action has lasted for 0.35 seconds (meeting the total delay condition); the turbine trip signal detection unit does not return a trip signal (due to high-pressure main steam valve jamming); the reliable speed signal displays 3200rpm ≥ 3190rpm; the generator-transformer unit main switch status detection unit confirms that the main switch has been opened. If all four conditions are met simultaneously, the DCS control module triggers subsequent protection actions to identify the valve misalignment condition.

[0051] S5. If the four conditions are met, the DCS control module triggers the boiler to trip, opens the boiler PCV valve, opens the condenser vacuum breaker valve, opens the high and low pressure bypass, and completely stops the vacuum pump; if the four conditions are not met simultaneously, the execution state of step S2 is maintained, and the process returns to step S1, and steps S3-S4 are repeated until the four conditions are met.

[0052] In some embodiments, after the generator differential protection operates, according to S4, if all four conditions are met: the protection operation has continued for a total delay of 0.38s calculated in S3, no turbine trip signal has been received (due to jamming of the intermediate-pressure main steam valve), the reliable speed signal of 3200rpm is greater than or equal to the corrected speed threshold of 3195rpm, and the generator-transformer unit main switch has been tripped, the DCS control module immediately triggers the following actions: triggering the boiler MFT trip via the FSSS system to cut off the supply of pulverized coal and fuel oil; opening the boiler PCV valve for rapid pressure relief; opening the condenser vacuum breaker valve to break the vacuum and brake the turbine; simultaneously opening the high and low pressure bypasses to release steam; and shutting down all three vacuum pumps. Within 10 seconds after the action, the boiler main steam pressure drops from 18MPa to 6MPa, and the turbine speed gradually decreases, avoiding the risk of overspeed and hydrogen explosion.

[0053] If the S4 judgment is not met (e.g., the reliable speed of 3150 rpm is less than the threshold), then the state of the EH oil pump being completely stopped and the plant power supply being switched to the standby transformer in S2 will be maintained. The system will return to S1 to continue collecting data, repeat the algorithm calculation in S3 and the condition judgment in S4, until the speed reaches the target and the four conditions are met, and then the corresponding protection action will be triggered.

[0054] It should be understood that the sequence number of each step in the above embodiments does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

[0055] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A generator-transformer unit electrical fault protection tripping function extension device, characterized in that, The device includes: The generator-transformer unit electrical fault protection detection module is used to monitor the operation status of the generator-transformer unit's electrical fault protection in real time. The electrical fault protection operations include differential protection, stator grounding protection, inter-turn short circuit protection, and heavy gas protection. The DCS control module is connected to the generator-transformer group electrical fault protection and detection module. The DCS control module includes a logic control unit, an adaptive delay unit, a speed threshold correction unit, and a signal filtering and reliability verification unit. The logic control unit is connected to the adaptive delay unit, the speed threshold correction unit, and the signal filtering and reliability verification unit, respectively. An execution module is connected to the DCS control module. The execution module includes an EH oil pump control unit, a boiler control unit, a valve control unit, and a vacuum pump control unit. The EH oil pump control unit, boiler control unit, valve control unit, and vacuum pump control unit are each connected to a logic control unit. A status detection module is connected to the DCS control module. The status detection module includes a turbine trip signal detection unit, a TSI speed detection unit, a generator-transformer main switch status detection unit, and an operating condition parameter acquisition unit. The turbine trip signal detection unit and the generator-transformer main switch status detection unit are respectively connected to the logic control unit. The TSI speed detection unit is connected to the signal filtering and reliability verification unit. The operating condition parameter acquisition unit is used to collect real-time load, main steam pressure, and historical steam valve closing time data of the unit. The operating condition parameter acquisition unit is connected to the adaptive delay unit.

2. The generator-transformer unit electrical fault protection tripping function extension device according to claim 1, characterized in that, The logic control unit is used to trigger the EH oil pump control unit to completely stop the EH oil pump without delay when the generator-transformer group electrical fault protection detection module detects any electrical fault protection action, and at the same time trigger a regular trip action, which includes: generator-transformer group main switch trip, excitation switch trip, turbine ETS trip, and switching of plant auxiliary power.

3. The generator-transformer unit electrical fault protection tripping function extension device according to claim 1, characterized in that, The adaptive delay unit is used to calculate the redundant delay value by weighted averaging based on the historical valve closing time data collected by the operating condition parameter acquisition unit, and to calculate the total delay of the turbine trip signal. The total delay is equal to the sum of the maximum historical valve closing time and the redundant delay value.

4. The generator-transformer unit electrical fault protection tripping function extension device according to claim 1, characterized in that, The speed threshold correction unit is used to perform linear correction based on the reference speed increase value of 3180 rpm during the period from the generator fully shedding rated load to the normal closing of the turbine valves, combined with real-time load and main steam pressure parameters. The correction formula is as follows: in, K 1 represents the load correction factor, with a value ranging from 0.

002. rpm / MW -0.005 rpm / MW , K 2 is the main steam pressure correction factor, with a value range of 1. rpm / MPa -3 rpm / MPa The corrected speed threshold is no less than 3150 rpm and no more than 3250 rpm.

5. The generator-transformer unit electrical fault protection tripping function extension device according to claim 1, characterized in that, The signal filtering and reliability verification unit is used to process the speed signal collected by the TSI speed detection unit using a moving average filter to obtain the speed value. The filter window length is set to 5-10 sampling periods. The reliability of the signal is judged by the signal fluctuation amplitude of m consecutive sampling periods. When the fluctuation amplitude is ≤5rpm, it is determined to be a reliable signal; otherwise, it is determined to be an interference signal and signal calibration is triggered. The formula for calculating the rotational speed is: in, For the first n The filtered rotational speed value after each sampling period. The length of the filter window. For the first ni The original rotational speed value for each sampling period.

6. The generator-transformer unit electrical fault protection tripping function extension device according to claim 1, characterized in that, In the execution module: The EH oil pump control unit is used for synchronous shutdown control of the EH oil pump in the unit; The boiler control unit trips the boiler by triggering the main fuel trip (MFT). The valve control unit uses an independent electromagnetic drive module for the rapid opening of boiler PCV valves, condenser vacuum breaker valves, and high and low pressure bypasses.

7. The generator-transformer unit electrical fault protection tripping function extension device according to claim 1, characterized in that, The DCS control module is also equipped with a manual intervention unit. When the logic control unit, adaptive delay unit, speed threshold correction unit, and signal filtering and reliability verification unit malfunction, the various actions of the execution module can be triggered manually.

8. A method for tripping protection of a generator-transformer unit in the event of an electrical fault, the method being based on the functional extension device according to any one of claims 1-7, characterized in that, The method includes the following steps: S1. The generator-transformer unit electrical fault protection detection module monitors the electrical fault protection status of the generator-transformer unit. The operating condition parameter acquisition unit continuously collects the real-time load, main steam pressure and historical steam valve closing time of the unit. The status detection module collects the turbine trip signal, the original TSI speed signal and the status of the generator-transformer unit main switch. S2. When any electrical fault protection action is detected, the DCS control module triggers the EH oil pump control unit to completely stop all EH oil pumps; triggers the main switch of the generator-transformer unit to trip, the excitation switch to trip, the turbine ETS to trip, and switches the plant auxiliary power. After the turbine trips, the boiler is tripped in conjunction. S3. The adaptive delay unit determines the total delay based on the historical steam valve closing time; the speed threshold correction unit calculates the corrected speed threshold based on the real-time load and main steam pressure of the unit; the signal filtering and credibility verification unit performs moving average filtering on the original TSI speed signal to obtain a credible speed signal. S4. The logic control unit of the DCS control module determines whether the following four conditions are met simultaneously: the electrical fault protection action has continued for the total delay obtained in step S3, no turbine trip signal has been received, the reliable speed signal is ≥ the corrected speed threshold, and the generator-transformer group main switch is in the open position. S5. If the four conditions are met, the DCS control module triggers the boiler to trip, opens the boiler PCV valve, opens the condenser vacuum breaker valve, opens the high and low pressure bypass, and completely stops the vacuum pump; if the four conditions are not met simultaneously, the execution state of step S2 is maintained, and the process returns to step S1, and steps S3-S4 are repeated until the four conditions are met.

9. The generator-transformer unit electrical fault protection tripping method according to claim 8, characterized in that, The specific steps of step S3 are as follows: S31. The adaptive delay unit calculates the redundant delay value by weighted averaging based on historical valve closing time data, and calculates the total delay of the turbine trip signal. The total delay is equal to the sum of the maximum historical valve closing time and the redundant delay value. S32. The speed threshold correction unit calculates the corrected speed threshold based on real-time load and main steam pressure parameters using a linear correction formula; the correction formula is: in, K 1 represents the load correction factor, with a value ranging from 0.

002. rpm / MW -0.005 rpm / MW , K 2 is the main steam pressure correction factor, with a value range of 1. rpm / MPa -3 rpm / MPa The corrected speed threshold is no less than 3150 rpm and no more than 3250 rpm; S33. The signal filtering and reliability verification unit performs a moving average filter on the original TSI speed signal to obtain the speed value, and simultaneously verifies the reliability of the speed value. If it is an interference signal, calibration is triggered until a reliable speed signal is obtained; the calculation formula for the speed value is: in, For the first n The filtered rotational speed value after each sampling period. The length of the filter window. For the first ni The original rotational speed value for each sampling period.

10. The generator-transformer unit electrical fault protection tripping method according to claim 8, characterized in that, In step S2, the method further includes the following steps: When the logic control unit, adaptive delay unit, speed threshold correction unit, and signal filtering and reliability verification unit malfunction, the various actions of the execution module are triggered manually.

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