Anti-interference device and method of rotor ground protection combined with working condition double identification

Abstract

This invention provides a rotor grounding protection anti-interference device and method combining dual operating condition identification, belonging to the field of generator protection technology. Addressing the problem of false alarms caused by mutual interference between DC insulation detection and rotor grounding protection during DC excitation, the device includes rotor grounding protection, DC excitation contact detection, generator terminal voltage acquisition, operating condition judgment, and protection activation / deactivation control modules. The DC excitation contact is connected to a separate input circuit, and the operating condition is determined by combining the generator terminal three-phase voltage signal. When DC excitation is activated and the generator terminal voltage is lower than 10% of the rated voltage, rotor grounding protection is automatically deactivated; otherwise, it is automatically activated. This invention eliminates false alarms, solves the problems of unverifiable contact reliability and interference during excitation switching, improves protection stability and reliability, and has strong compatibility, low modification cost, and optimized unit startup efficiency.

Description

Technical Field

[0001] This invention relates to the field of generator protection technology, specifically to a rotor grounding protection anti-interference device and method that combines dual identification of operating conditions. Background Technology

[0002] Rotor grounding protection is a crucial protective device for generators, used to detect the insulation status of the rotor windings to ground. It operates on two principles: injection-type and ping-pong-type, both using loop calculations to monitor the rotor winding insulation status. Generator excitation methods primarily include DC excitation and residual voltage excitation: DC excitation provides the initial excitation current through the plant's DC system and is suitable for scenarios with insufficient residual voltage at the generator terminals; residual voltage excitation utilizes the residual voltage at the generator terminals to establish initial excitation, requiring no additional DC power supply.

[0003] In actual operation, during the DC excitation phase, the DC insulation detection device and the rotor grounding protection device form a parallel circuit through the rotor windings. Their respective grounding points detect each other, leading to false alarms from both devices, such as the DC insulation detection device reporting "DC grounding" and the rotor grounding protection device reporting "rotor grounding." This affects operators' judgment of the equipment's true condition and may even cause unnecessary shutdowns. While residual voltage excitation can avoid this interference, the system automatically switches to DC excitation when the unit is in standby mode for extended periods, restarting after maintenance, or when residual voltage is insufficient, causing the interference problem to recur. Therefore, an optimized rotor grounding protection scheme that can adapt to both excitation methods and avoid mutual interference is urgently needed.

[0004] Existing technologies employ a method of connecting the auxiliary contacts of a DC excitation relay in series with the rotor grounding protection function pressure plate circuit to construct automatic rotor grounding protection activation / deactivation logic. When the DC excitation contactor operates, its normally closed contact opens, automatically deactivating rotor grounding protection, while a DC insulation monitoring device simultaneously detects the rotor winding's insulation to ground. When DC excitation ends, the contactor de-energizes, the normally closed contact closes, and the rotor grounding protection function is automatically activated. However, this approach has the following drawbacks: 1) It cannot verify the reliability of the auxiliary contacts of the DC excitation relay. If the contacts experience faults such as adhesion or poor contact, the rotor grounding protection will fail to activate properly, leaving a safety hazard; 2) It relies solely on the relay contact status to determine the excitation condition, lacking a redundant judgment mechanism, resulting in a high risk of misjudgment of the operating condition.

[0005] Abandoning the DC excitation method and prioritizing the residual voltage excitation method, which relies on the residual voltage at the generator terminals to establish initial excitation and avoid parallel interference between the DC excitation circuit and the rotor grounding protection circuit, thus reducing false alarms, also has the following drawbacks: 1) Limited applicability: When the unit is on standby for a long time, started after maintenance, or when the residual voltage at the generator terminals is lower than the voltage establishment threshold, the system will automatically switch to DC excitation, and the mutual interference between the two devices still cannot be avoided; 2) It does not fundamentally solve the interference problem in the DC excitation stage, but only temporarily alleviates it by avoiding the use of DC excitation, resulting in poor compatibility and practicality. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to provide a rotor grounding protection anti-interference device and method that combines dual identification of operating conditions, which solves the problems in the prior art where the reliability of the contacts cannot be verified and the DC excitation switching of residual voltage excitation is still subject to interference.

[0007] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: The rotor grounding protection anti-interference device with dual operating condition identification includes a rotor grounding protection device, a DC excitation contact detection module, a terminal voltage acquisition module, an operating condition judgment module, and a protection activation / deactivation control module. The DC excitation contact detection module is connected to the separate input channel of the rotor grounding protection device to detect the engagement status of the auxiliary contacts of the DC excitation contactor and output the contact status signal. The generator terminal voltage acquisition module is signal-connected to the operating condition judgment module. It is used to acquire the three-phase voltage signal at the generator terminal, calculate the effective value of the voltage at the generator terminal, and then output it to the operating condition judgment module. The operating condition judgment module is connected to the DC excitation contact detection module and the terminal voltage acquisition module respectively, and is used to receive contact status signals and the effective value of terminal voltage and perform operating condition judgment. The protection activation / deactivation control module is connected to the operating condition judgment module and the rotor grounding protection device, respectively. It is used to output control signals based on the judgment result of the operating condition judgment module to control the activation / deactivation status of the rotor grounding protection device. The rotor grounding protection device is compatible with both injection-type and ping-pong-type rotor grounding protection principles. It is used to detect the insulation resistance of the rotor winding to ground and output a protection action signal.

[0008] The DC excitation contact detection module described above has a separate input channel with opto-isolation design, and the input voltage is compatible with DC 110V / 220V systems. The input channel is also equipped with a hardware filtering circuit.

[0009] The aforementioned terminal voltage acquisition module receives the terminal voltage signal through a three-phase voltage transformer. It is internally equipped with voltage divider resistors, filter circuits, and analog-to-digital converter chips. The module's sampling frequency is not less than 1kHz, and the voltage measurement error does not exceed ±1%.

[0010] The aforementioned protection activation / deactivation control module adopts a dual control mechanism of "hardware control + software interlocking". On the hardware side, the core power supply or sampling circuit of the rotor grounding protection device is controlled through relay contacts, and on the software side, the protection output is interlocked through the internal logic of the rotor grounding protection device.

[0011] The above-mentioned device is compatible with both 110V and 220V DC excitation power supply systems, and the voltage level can be switched through hardware jumpers; the rated value of the generator terminal voltage can be set through the setting value in the rotor grounding protection device.

[0012] The device also includes a unit parameter adaptive configuration module, which is signal-connected to the operating condition judgment module. It is used to read the generator's rated capacity, voltage level, excitation curve parameters, and retrieve the unit's historical excitation operation data. It dynamically adjusts the generator terminal voltage judgment threshold through a fuzzy algorithm, with a setting range of 5%-15% of the rated voltage, and supports manual calibration of the threshold. The operating condition judgment module has built-in multi-operating condition subdivision identification logic, which subdivides the DC excitation operating condition into the initial excitation stage, the middle stage of voltage build-up, and the critical period of excitation completion, and subdivides the non-DC excitation operating condition into the residual voltage excitation operating condition, the normal operation operating condition, and the shutdown standby operating condition.

[0013] The aforementioned protection activation / deactivation control module is equipped with a redundant backup unit and a pre-switching control unit. The redundant backup unit features a dual-module architecture with primary and backup modules. The primary and backup modules synchronously receive signals from the operating condition judgment module and synchronize their operating status in real time. When the primary module fails, the backup module seamlessly switches over with a switching time of ≤5ms. The pre-switching control unit is used to monitor the difference between the terminal voltage and the set threshold in real time. When the difference is within the preset range (±5% of the threshold), the hardware circuit of the target activation / deactivation state is placed in the standby state. The hardware control circuit of the protection activation / deactivation control module adopts a dual-relay parallel design and is equipped with a relay status real-time monitoring unit. When a relay fails, an alarm signal is triggered immediately.

[0014] The device also includes a linkage communication module and a data upload and remote control unit. The linkage communication module adopts the Modbus / Profinet industrial standard communication protocol and is bidirectionally connected to the DC insulation detection device and the generator excitation system, respectively, to realize the linkage of working modes with the DC insulation detection device and the interaction of operating data with the excitation system. The data upload and remote control unit is connected to the power plant's background monitoring system and is also connected to the signals of each module in the device. It is used to collect the device's operating data and upload it to the background monitoring system, while receiving remote control commands from the background system to realize the setting of device parameters and the switching of protection activation and deactivation modes.

[0015] The method for using the above-mentioned rotor grounding protection anti-interference device that combines dual identification of operating conditions includes the following steps: Step 1: After the unit starts, the DC excitation contact detection module detects the status of the auxiliary contact of the DC excitation contactor in real time and outputs the contact status signal. The generator terminal voltage acquisition module continuously acquires the three-phase voltage signal of the generator terminal and calculates the effective value of the voltage at the computer terminal, and transmits both to the operating condition judgment module. Step 2: The operating condition judgment module performs dual operating condition judgment based on the connection point status signal and the effective value of the terminal voltage: If the DC excitation connection is in the engaged state and the effective value of the terminal voltage is lower than 10% of the rated voltage, it is judged as the DC excitation incomplete operating condition; if the DC excitation connection is in the disengaged state, or the effective value of the terminal voltage is higher than 10% of the rated voltage, it is judged as the non-DC excitation operating condition or the DC excitation completed operating condition. Step 3: The protection activation / deactivation control module outputs control signals based on the operating condition judgment results to control the activation / deactivation of the rotor grounding protection device: if it is determined that the DC excitation is not completed, the rotor grounding protection device is deactivated; if it is determined that the non-DC excitation is completed or the DC excitation is completed, the rotor grounding protection device is activated, and the rotor winding insulation to ground detection and protection action logic are executed. Step 4: Monitor the status of the DC excitation contact and the changes in the terminal voltage in real time. When the operating conditions change, the protection activation / deactivation control module will synchronously switch the activation / deactivation status of the rotor grounding protection device, and the switching delay will not exceed 100ms.

[0016] In Step 3 above, when the rotor grounding protection device is deactivated, the protection activation / deactivation control module uses a dual mechanism of "hardware control + software interlock" to disconnect the hardware contacts and interlock the protection output of the rotor grounding protection device in software; when the rotor grounding protection device is activated, the hardware contacts are closed and the protection output of the rotor grounding protection device is unlocked in software.

[0017] In Step 3 above, after the rotor grounding protection device is put into operation, it selects the injection type or ping-pong type protection principle according to the preset value. The rotor winding insulation to ground is detected through the process of signal injection, grounding detection and fault judgment. If a fault is detected, an alarm or trip protection action signal is output.

[0018] The aforementioned Step 1 includes a voltage threshold adaptive setting step: the generator rated capacity, voltage level, and excitation curve parameters are read by the unit parameter adaptive configuration module. The generator terminal voltage change pattern at the completion of DC excitation is retrieved from the historical excitation operation data of the unit. The generator terminal voltage judgment threshold is dynamically set using a fuzzy algorithm and sent to the operating condition judgment module. The threshold setting range is 5%-15% of the rated voltage, and manual calibration is also supported. In Step 2, the operating condition judgment module performs multi-operating condition subdivision identification. Combining the DC excitation contact status and the set generator terminal voltage threshold, the DC excitation operating condition is subdivided into the initial excitation stage, the middle stage of voltage build-up, and the critical period of excitation completion. The non-DC excitation operating condition is subdivided into the residual voltage excitation operating condition, the normal operation operating condition, and the shutdown standby operating condition. In Step 3, the protection activation / deactivation control module executes differentiated protection activation / deactivation strategies for different subdivision operating conditions. For the critical period of excitation completion, a soft protection activation strategy is adopted, which first unlocks the software lockout, delays for 50ms, and then closes the hardware contact.

[0019] Before outputting the operating condition judgment result, the Step 2 operating condition judgment module first determines whether the difference between the terminal voltage and the set threshold is within the preset (±5%) range. If so, it triggers the hardware circuit pre-switching preparation and puts the hardware relay of the target enabling / disabling state into the energized / disengaged ready-to-operate state. When the operating condition changes in Step 4, the protection enabling / disabling seamless switching is achieved based on the pre-switching preparation state, with an overall switching delay of ≤10ms. During the operation of the protection enabling / disabling control module, the main and backup redundant modules mutually check the operating status in real time. When the main module fails, the backup module takes over the control without disturbance, and the dual relay parallel circuit synchronously monitors the working status. When a single relay fails, an alarm is immediately triggered and the control function is maintained by the other relay.

[0020] In Step 3 above, while the protection activation / deactivation control module outputs the protection activation / deactivation control signal, the linkage communication module sends a mode switching command to the DC insulation detection device. When the rotor grounding protection device is deactivated, the DC insulation detection device is triggered to enter the high-precision detection mode. When the rotor grounding protection device is activated, the DC insulation detection device is triggered to return to the normal detection mode. The linkage communication module simultaneously collects the excitation command and excitation current signal from the generator excitation system as auxiliary criteria for the operating condition judgment module. The operating status, operating condition judgment results, protection activation / deactivation status, and fault information of each module in the device are uploaded in real time to the power plant's background monitoring system by the data upload and remote control unit. It also supports remote setting of voltage thresholds and switching between automatic and manual modes for protection activation / deactivation.

[0021] This invention discloses a rotor grounding protection anti-interference device and method that combines dual identification of operating conditions. By connecting the DC excitation contact to a separate input circuit of the rotor grounding protection device and combining it with the three-phase voltage signal at the turbine terminals to assist in judging the operating conditions, the precise activation and deactivation of rotor grounding protection is achieved. When DC excitation is activated and the turbine terminal voltage is lower than 10% of the rated voltage, rotor grounding protection is automatically deactivated; when non-DC excitation mode is used or the turbine terminal voltage is higher than 10% of the rated voltage, rotor grounding protection is automatically activated. This effectively avoids false alarms and solves the problems in the prior art where contact reliability cannot be verified and DC excitation switching from residual voltage excitation is still subject to interference. The beneficial effects of this invention are as follows: 1) By using both DC excitation contact and generator terminal voltage for dual judgment, the excitation condition is accurately identified, completely eliminating false alarms during the DC excitation stage; 2) A fuzzy inference model is constructed to dynamically set the generator terminal voltage judgment threshold, adapting to the excitation characteristics of different generator units and solving the problem of poor adaptability of fixed thresholds; 3) Based on the set threshold, the excitation condition is finely subdivided, and differentiated protection activation / deactivation strategies are configured to avoid protection maloperation during condition switching; 4) Seamless switching of protection activation / deactivation and multiple redundant protections are achieved through pre-switching, main / backup redundant modules, and dual relay parallel circuits, eliminating the risk of protection failure due to protection vacuum and single equipment failure; 5) Linkage with the working mode of the DC insulation detection device is achieved, accurately switching the detection mode, further avoiding mutual interference between devices, and improving the accuracy of rotor winding insulation detection; 6) Excitation system operating data is collected as an auxiliary criterion for condition judgment, further improving the accuracy and reliability of condition identification; 7) Real-time uploading of equipment operation data and remote control from the power plant's backend are achieved, integrating into the power plant's intelligent control system to enable remote setting and switching, improving operation and maintenance efficiency and reducing labor costs; 9) Seamless switching of protection activation and deactivation is achieved through the pre-switching control unit, reducing switching delay and completely eliminating the risk of short-term protection vacuum; 10) Dual-module redundant backup and dual-relay parallel hardware circuits provide dual redundancy protection from the control and hardware levels, ensuring uninterrupted switching in case of main module failure and no impact on control functions in case of single relay failure, significantly improving the reliability of equipment operation; 11) No large-scale modification of the existing unit's excitation system and protection devices is required, optimizing unit start-up efficiency and ensuring excitation success rate. Attached Figure Description

[0022] The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 This is a schematic diagram of the device structure of the present invention; Figure 2 This is a block diagram illustrating the overall principle and structure of the present invention; Figure 3This is a logic block diagram of the rotor grounding protection under adaptive operating conditions of the present invention. Detailed Implementation

[0023] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0024] Example 1: like Figure 1-3 As shown, the rotor grounding protection anti-interference device, which combines dual operating condition identification, includes a rotor grounding protection device (compatible with injection type and ping-pong type), a DC excitation contact detection module, a terminal voltage acquisition module, an operating condition judgment module, and a protection on / off control module. These modules work together to achieve precise control of the rotor grounding protection. The specific architecture is as follows: Rotor grounding protection device: The core actuator is used to detect the insulation resistance of the rotor winding to ground and output a protection action signal; DC excitation contact detection module: Connects to the auxiliary contacts of the DC excitation contactor to detect the activation status of the DC excitation operation in real time; Generator terminal voltage acquisition module: Acquires the three-phase voltage signal at the generator terminal through a voltage transformer, and the effective value of the voltage at the computer terminal; Operating condition judgment module: Receives DC excitation contact status signal and generator terminal voltage signal to determine the current excitation operating condition of the unit; Protection activation / deactivation control module: Based on the operating condition judgment result, output control signal to rotor grounding protection device to control its activation / deactivation status.

[0025] Key circuit: 1) DC excitation contact input circuit An independent input channel is added to the rotor grounding protection device, specifically for connecting the auxiliary contacts of the DC excitation contactor. This input channel adopts an opto-isolation design, and the input voltage is compatible with DC 110V / 220V systems. Hardware filtering circuits eliminate contact jitter interference, ensuring the accuracy of contact status detection.

[0026] 2) Terminal voltage acquisition circuit The generator terminal voltage acquisition module receives the generator terminal voltage signal through a three-phase voltage transformer. The analog voltage signal is converted into a digital signal via voltage divider resistors, a filter circuit, and an analog-to-digital converter chip, and then transmitted to the operating condition judgment module. The sampling frequency of the acquisition circuit is no less than 1kHz, and the voltage measurement error does not exceed ±1%, ensuring the accuracy of the generator terminal voltage detection.

[0027] 3) Protection activation / deactivation control circuit The protection activation / deactivation control loop employs a dual mechanism of "hardware control + software interlocking." On the hardware side, relay contacts control the core power supply or sampling circuit of the rotor grounding protection device. On the software side, the protection output is interlocked via the internal logic of the protection device. When the deactivation conditions are met, the hardware contacts open and the software interlocks the output; when the activation conditions are met, the hardware contacts close and the software unlocks the output, ensuring control reliability.

[0028] Control Logic Flow After the unit starts up, the DC excitation contact detection module monitors the status of the auxiliary contacts of the DC excitation contactor in real time, and the generator terminal voltage acquisition module continuously acquires the three-phase voltage at the generator terminal and calculates the effective value. The operating condition judgment module receives the above two signals and performs operating condition judgment: 1) If the DC excitation contact is in the "engaged" state and the effective value of the terminal voltage is lower than 10% of the rated voltage, it is determined as "DC excitation not completed condition".

[0029] 2) If the DC excitation contact is in the "out" state, or the effective value of the terminal voltage is higher than 10% of the rated voltage, it is determined as "non-DC excitation condition or DC excitation completed condition".

[0030] The protection activation / deactivation control module outputs control signals based on the operating condition judgment results: 1. For the "DC excitation not completed" condition, the rotor grounding protection device should be deactivated. 2. For “non-DC excitation operation or DC excitation completed operation”, the rotor grounding protection device is activated, and the insulation detection and protection action logic is executed normally.

[0031] The system monitors the status of the DC excitation contact and changes in the terminal voltage in real time. When the operating conditions change, the protection on / off status changes synchronously, with a switching delay of no more than 100ms.

[0032] Adaptive design 1) Compatible with injection-type and ping-pong-type rotor grounding protection principles. The corresponding principle is selected through the internal setting of the protection device, without the need for additional modification of the hardware circuit.

[0033] 2) It is compatible with both 110V and 220V DC excitation power supply systems, and the voltage level can be switched through hardware jumpers, making it highly versatile.

[0034] 3) The rated value of the generator terminal voltage can be set by the protection device to adapt to generator sets of different capacities and voltage levels.

[0035] Example 2: This embodiment illustrates the role of the unit parameter adaptive configuration module in rotor grounding protection and interference prevention. The unit parameter adaptive configuration module is bidirectionally connected to the operating condition judgment module and has a built-in data storage unit, fuzzy algorithm calculation unit, and human-machine interface. Its core function is to dynamically adjust the generator terminal voltage judgment threshold through a fuzzy algorithm. The specific modeling and calculation process is as follows: 1. Definition of input and output variables in fuzzy inference models Input variables: The two core parameters that have the most significant impact on the generator's start-up characteristics are selected as inputs to the fuzzy inference model, namely the generator's rated capacity. (Unit: MW) Historical average excitation completion voltage (unit:% , (Rated generator terminal voltage); Output variable: Terminal voltage judgment threshold (unit:% The output range is limited to 5%~15%. To match the start-up and voltage-building characteristics of different generator units.

[0036] 2. Fuzzification of variables For input variables Fuzzy hierarchical classification is performed: defined as three fuzzy subsets: small S, medium M, and large L, with a universe of discourse of [50, 1000]MW. The membership function adopts the triangular membership function, and the specific segments are: S (50~300MW), M (300~600MW), and L (600~1000MW). For input variables Fuzzy hierarchical classification is performed, defined as three fuzzy subsets: low L, medium M, and high H, with a universe of discourse of [5,15]%. The membership function uses a triangular membership function, specifically segmented as: L(5~8%) M (8~12%) H (12~15%) ); For output variables Fuzzy hierarchies are defined as follows: low L, low-medium ML, medium M, medium-high MH, and high H, with a universe of discourse of [5, 15]%. The membership function adopts a triangular membership function to improve the fineness of threshold tuning.

[0037] Fuzzy rule base establishment Based on the excitation and pressure build-up test data and field operation experience of hydro-generators and steam-generators, nine core fuzzy inference rules were established. These rules adopt the "IF" formula. For ×× AND For ××, THEN The format is “××”, and the specific rules are as follows: 1. IF For S AND For L, THEN Let L be the value. 2. IF For S AND For M, THEN For ML; 3. IF For S AND For H, THEN For M; 4. IF For M AND For L, THEN For ML; 5. IF For M AND For M, THEN For M; 6. IF For M AND For H, THEN For MH; 7. IF For L AND For L, THEN For M; 8. IF For L AND For M, THEN For MH; 9. IF For L AND For H, THEN For H.

[0038] Fuzzy reasoning and defuzzification Fuzzy inference employs the Mamdani inference method, which calculates the fuzzy membership distribution of the output variable based on the fuzzy membership degree of the input variable and the fuzzy rule base. Defuzzification employs the centroid method, which converts the fuzzy subsets obtained from fuzzy inference into precise threshold values. The centroid method calculation formula is as follows: ; In the formula: , , which represents the upper and lower bounds of the domain of the output variable; The universe of discourse element of the output variable; For output variables The membership function.

[0039] Data retrieval and threshold output Data storage unit pre-stores generator rated capacity Rated voltage The system retrieves basic parameters such as the excitation curve, and simultaneously accesses historical excitation operation data (≥30 sets of valid excitation data) from the power plant's DCS system for the past 6 months to calculate the average historical excitation completion voltage. : ; In the formula: The number of valid historical excitation data sets, n≥30; For the first The terminal voltage value when the second excitation is completed.

[0040] The fuzzy algorithm processing unit will and Substituting into the above fuzzy inference model, the accurate terminal voltage judgment threshold is calculated. and will The data is sent to the operating condition judgment module for storage; the human-machine interface allows maintenance personnel to manually calibrate the threshold based on the actual on-site operating conditions, and the manually calibrated value takes precedence over the algorithm setting value.

[0041] In the case where the unit parameter adaptive configuration module is set, the operating condition judgment module has built-in multi-operating condition subdivision identification logic, receiving the DC excitation contact status signal (engaged / deactivated) and the settings of the unit parameter adaptive configuration module. Combined with the effective value of the terminal voltage This enables fine-grained subdivision of the excitation operating conditions. All operating condition judgments employ a three-times sampling confirmation mechanism to eliminate misjudgments caused by signal interference. The specific subdivision rules are as follows: 1) DC excitation mode (DC excitation contact is in the "engaged" state) Initial stage of excitation: The unit is in the initial stage of DC excitation voltage buildup, and the terminal voltage is extremely low. Mid-term pressure building: The unit is in the process of DC excitation and voltage build-up, and the terminal voltage is steadily rising; Excitation completion critical period: The unit is nearing the completion of DC excitation, and the terminal voltage is about to reach the judgment threshold.

[0042] 2) Non-DC excitation operation (DC excitation contacts are in the "out" state) Residual pressure excitation condition: The unit relies on the residual voltage at the generator terminal to build up voltage, and the voltage is in the process of rising; Normal operating conditions: The generator set voltage is complete, and the generator terminal voltage is stable within the rated voltage range; Standby operation condition: The unit is in a shutdown or standby state, with no or low pressure at the unit terminals.

[0043] Protection activation / deactivation control module: It adopts a dual control mechanism of "hardware control + software interlocking", with a built-in differentiated protection activation / deactivation strategy library. It is linked with the multi-condition subdivision identification logic of the operating condition judgment module. After receiving the subdivision results of the operating conditions, it outputs the corresponding control signal to the rotor grounding protection device to control its activation / deactivation status. On the hardware side, it controls the core power supply or sampling circuit of the rotor grounding protection device through relay contacts. On the software side, it interlocks the protection output through the internal logic of the rotor grounding protection device to ensure control reliability.

[0044] A method for preventing interference by combining a unit parameter adaptive configuration module with dual operating condition identification for rotor grounding protection was established. The specific steps include: S0 Terminal Voltage Judgment Threshold Adaptive Setting The generator's rated capacity is read from the data storage unit of the unit parameter adaptive configuration module. Rated voltage Basic parameters such as excitation curves were obtained, and historical excitation operation data of the units for the past 6 months were retrieved from the power plant's DCS system. ≥30 sets of valid data were selected, and the average historical excitation completion voltage was calculated. ;Will and The input fuzzy algorithm processing unit calculates the accurate terminal voltage judgment threshold through a process of fuzzification processing → fuzzy rule reasoning → centroid method defuzzification. (5%~15%) ), and will The data is sent to the operating condition judgment module for storage. If maintenance personnel need to adjust the data according to the actual situation on site, they can manually calibrate the threshold through the human-machine interface. The manually calibrated value will override the algorithm setting value.

[0045] S1 Signal Acquisition and Real-time Transmission After the unit starts up, the DC excitation contact detection module monitors the status of the auxiliary contacts of the DC excitation contactor in real time and outputs a digital contact status signal; the generator terminal voltage acquisition module continuously acquires the three-phase voltage signal at the generator terminal through the three-phase voltage transformer, and after voltage division, filtering, and analog-to-digital conversion, the effective value of the voltage at the computer terminal is calculated. ; connect the contact status signal and All data are sampled at 10ms intervals and transmitted in real time to the operating condition judgment module.

[0046] S2 Multi-condition Fine-grained Subdivision Recognition The operating condition judgment module receives contact status signals and Combined with step S0 tuning The process involves three consecutive sampling confirmations, dual criteria, and multi-condition detailed identification. The specific judgment process is as follows: 1. First, determine the status of the DC excitation contact. If it is in the "engaged" state, enter the DC excitation mode subdivision; if it is in the "disengaged" state, enter the non-DC excitation mode subdivision. 2. Regarding Perform three consecutive samplings. If all three sampled values ​​meet the voltage range of a certain operating condition, it is determined to be the corresponding operating condition; otherwise, resample and judge. 3. Based on the working condition subdivision rules built into the working condition judgment module, output the specific working condition identification results and transmit the results to the protection activation / deactivation control module.

[0047] S3 Differentiated Protection Enabling / Deactivation Control The protection activation / deactivation control module receives the operating condition identification results from the operating condition judgment module, retrieves the corresponding differentiated protection activation / deactivation strategy from the strategy library, and controls the activation / deactivation status of the rotor grounding protection device through a dual mechanism of "hardware control + software interlocking". The specific strategy is as follows: 1. Initial stage of DC excitation / mid stage of voltage build-up: If the condition is determined to be that the DC excitation is not completed, the hardware control relay contacts are disconnected, and the protection output of the rotor grounding protection device is locked by the software. The rotor grounding protection device is then deactivated, and the DC insulation detection device is used to perform rotor winding insulation detection. 2. DC excitation completion critical period: A soft-start strategy is adopted for protection. First, the software lockout of the rotor grounding protection device is unlocked, and then the hardware control relay contact is closed after a 50ms delay. This avoids protection maloperation caused by rapid switching of operating conditions and achieves smooth protection activation. 3. Non-DC excitation - residual voltage excitation condition / normal operation condition / shutdown standby condition: When the condition is determined to be non-DC excitation condition or DC excitation completed condition, the hardware control relay contact is closed and the software lockout is unlocked, and the rotor grounding protection device is put into normal operation. The rotor grounding protection device selects the injection type or ping-pong type protection principle according to the preset value, and realizes the rotor winding insulation to ground through the process of "signal injection → grounding detection → fault judgment". If a grounding fault is detected, an alarm or trip protection action signal is immediately output.

[0048] S4 Operating Condition Switching and Synchronization Adjustment The status of the DC excitation contact is monitored in real time with a period of 10ms. When the operating condition changes, the operating condition judgment module immediately updates the operating condition identification result and transmits it to the protection activation / deactivation control module. Based on the new operating condition result, the protection activation / deactivation control module synchronously switches the activation / deactivation status of the rotor grounding protection device, with an overall switching delay ≤100ms, of which the soft-connection switching delay during the excitation completion critical period is 50ms. Simultaneously, the device transmits the operating condition switching information, protection activation / deactivation status, and... The data is uploaded to the power plant's DCS system in real time, facilitating remote monitoring by maintenance personnel.

[0049] Example 3: This embodiment illustrates the role of the protection activation / deactivation control module equipped with a redundant backup unit and a pre-switching control unit in rotor grounding protection against interference. Based on the original dual mechanism of "hardware control + software interlocking," the protection activation / deactivation control module adds a redundant backup unit, a pre-switching control unit, and a relay status monitoring unit. The hardware control loop adopts a dual-relay parallel design. The specific structure and functions are as follows: 1. Pre-switching control unit: Connects to the terminal voltage acquisition module and operating condition judgment module to receive signals in real time. and Built-in threshold difference judgment logic, continuously calculating and The difference percentage ;when When it is determined that the operating condition is about to change, the hardware circuits of the target's activation / deactivation status are immediately placed in a standby state based on the prediction result of the operating condition judgment module (if the protection is activated, the closing relay is placed in a standby state; if the protection is deactivated, the opening relay is placed in a standby state), in preparation for seamless switching; when At this time, the hardware circuit returns to normal standby state.

[0050] 2. Redundant Backup Unit: Adopting a fully synchronous architecture with primary and backup dual modules, the primary and backup modules have completely identical hardware configurations and software logic. They synchronously receive operating condition signals from the operating condition judgment module and pre-switching signals from the pre-switching control unit. The primary and backup modules perform mutual checks on their operating status every 5ms, synchronously updating control commands and equipment status. When the primary module experiences communication failure, computational failure, or hardware failure, the backup module immediately and seamlessly takes over the control function with a switching time of ≤5ms. The faulty module also immediately triggers an alarm signal to the background monitoring system.

[0051] 3. Dual-relay parallel hardware control circuit: The original single-relay control circuit is upgraded to a dual-relay parallel design. The coils of the two relays synchronously receive the output signal of the control module, and the contacts are connected in parallel to the core power supply / sampling circuit of the rotor grounding protection device. When a single relay has a fault such as contact sticking or coil burnout, the other relay can independently maintain the control function, realizing uninterrupted hardware control of protection activation and deactivation.

[0052] 4. Relay Status Monitoring Unit: By collecting the operating current of the relay coil and the on / off status of the contacts, the unit monitors the operating status of the two relays in real time. When a single relay fault is detected, a local audible and visual alarm and a remote communication alarm are immediately triggered. At the same time, the fault information is uploaded to the power plant's DCS system for timely replacement by maintenance personnel. If both relays fail, the protection activation / deactivation control module is immediately locked and an emergency alarm is triggered.

[0053] 5. Existing functions are retained: The protection output is locked / unlocked through the internal logic of the rotor grounding protection device in the software, and the core power supply / sampling circuit is controlled by relay contacts in the hardware to achieve dual control of "hardware control + software lockout" and ensure the reliability of protection activation and deactivation.

[0054] When the protection activation / deactivation control module is equipped with a redundant backup unit and a pre-switching control unit, the rotor grounding protection anti-interference implementation method, which combines dual identification of operating conditions, specifically includes the following steps: S0 Terminal Voltage Judgment Threshold Adaptive Setting The generator rated capacity is read through the unit parameter adaptive configuration module. Rated voltage Based on fundamental parameters such as the excitation curve, historical excitation operation data (≥30 sets of valid data) of the unit over the past 6 months were retrieved from the power plant's DCS system to calculate the average historical excitation completion voltage. The threshold for determining the terminal voltage is dynamically set by using a fuzzy inference model, followed by fuzzy rule inference, and centroid method for defuzzification. (5%~15%) ),Will The pre-switching control unit sends data to the operating condition judgment module and the protection activation / deactivation control module; it supports manual threshold calibration, with the manual calibration value overriding the algorithm setting value.

[0055] S1 Signal Acquisition and Real-time Transmission After the unit starts up, the DC excitation contact detection module detects the status of the auxiliary contacts of the DC excitation contactor in real time with a sampling interval of 10ms and outputs a digital contact status signal; the generator terminal voltage acquisition module continuously acquires the three-phase voltage signal at the generator terminal, and after voltage division, filtering, and analog-to-digital conversion, the effective value of the voltage at the computer terminal is obtained. Connect the contact status signal and Real-time transmission to the operating condition judgment module, and simultaneously The data is transmitted to the pre-switching control unit of the protection activation / deactivation control module.

[0056] S2 Multi-condition Fine-grained Subdivision Recognition + Pre-switching Preparation 2.1 The operating condition judgment module receives contact status signals and , combined Perform three consecutive sampling confirmations + dual criteria + multi-condition detailed identification, output specific condition identification results and transmit them to the protection activation / deactivation control module; 2.2 Synchronous Calculation of the Pre-Switching Control Unit of the Protection Enabling / Disabling Control Module and The proportion of the difference ΔU, if If the system determines that a change in operating condition is imminent, and based on the prediction result of the operating condition judgment module, the hardware relays of the target deployment / retreat status are placed in a standby state; if The hardware circuit maintains a normal standby state.

[0057] S3 Differentiated Protection Enabling / Deactivation Control The main module of the protection activation / deactivation control module receives the operating condition identification result from the operating condition judgment module, retrieves the corresponding differentiated protection activation / deactivation strategy from the strategy library, and controls the activation / deactivation status of the rotor grounding protection device through a dual mechanism of "hardware control + software interlocking". The standby module synchronously receives and executes the same logic, but does not output hardware control signals and is in hot standby state. 1. DC excitation in the initial stage / mid stage of voltage build-up: If the condition is determined to be that the DC excitation is not completed, the hardware control relay contacts are disconnected, and the protection output of the rotor grounding protection device is locked by the software, and the rotor grounding protection device is controlled to exit. 2. DC excitation completion critical period: A soft-start strategy is adopted to first unlock the software interlock, and then close the hardware control relay contact after a 50ms delay to avoid protection maloperation caused by rapid switching of operating conditions. 3. Non-DC excitation - residual voltage excitation working condition / normal operation condition / shutdown standby working condition: When the condition is determined to be non-DC excitation working condition or DC excitation completed working condition, the hardware control relay contact is closed and the software lockout is unlocked, and the rotor grounding protection device is normally activated. The rotor grounding protection device selects the protection principle according to the preset value, performs rotor winding to ground insulation detection, and outputs alarm / trip signal when a fault occurs.

[0058] 4. The relay status monitoring unit collects the working status of the two relays in real time. When a single relay fails, an alarm is triggered immediately. The two relays maintain control functions independently without affecting the protection enabling or disabling operation.

[0059] S4 seamless switching between operating conditions + primary / standby redundancy protection 4.1 Monitor the DC excitation contact status in real time with a period of 10ms and When the operating conditions change, the pre-switching control unit has already placed the target hardware circuit in a ready-to-operate state, directly triggering the hardware circuit action and software logic switching, realizing seamless switching of protection activation and deactivation, with an overall switching delay of ≤10ms, completely eliminating the risk of short-term protection vacuum; 4.2 The main and backup modules of the protection activation and deactivation control module perform a mutual check of their operating status every 5ms. If a communication, calculation, or hardware failure is detected in the main module, the backup module immediately and seamlessly takes over the control function with a switching time of ≤5ms, ensuring the continuous and uninterrupted protection activation and deactivation control function. 4.3 After the operating condition switch is completed, the pre-switching control unit recalculates ΔU. If If the hardware circuit exits the standby state, it returns to normal standby. At the same time, the device uploads the operating condition switching information, protection activation / deactivation status, module operating status, and relay fault information to the power plant's DCS system in real time, facilitating remote monitoring by maintenance personnel.

[0060] S5 Hardware Circuit Fault Alarm and Handling The relay status monitoring unit continuously monitors the coil current and contact open / closed status of the two relays. When a single relay fault is detected, a local audible and visual alarm and a remote communication alarm are immediately triggered, and the faulty relay number and fault type are uploaded. Maintenance personnel can replace the faulty relay during non-operational periods. During the replacement process, the other relay continues to operate normally without affecting the overall function of the unit. If both relays are detected to be faulty, the protection activation / deactivation control module is immediately locked, an emergency alarm is triggered, and the rotor grounding protection device is put into manual activation / deactivation mode for on-site operation by maintenance personnel.

[0061] Example 3: This embodiment of the rotor grounding protection anti-interference device with dual operating condition identification includes a rotor grounding protection device, a DC excitation contact detection module, a generator terminal voltage acquisition module, an operating condition judgment module, a protection activation / deactivation control module, and a generator parameter adaptive configuration module. It also adds a linkage communication module and a data upload and remote control unit. All modules are integrated in the same protection cabinet and use an industrial bus to realize signal interaction between modules. The device is compatible with DC 110V / 220V excitation power supply systems. Voltage level switching is completed through hardware jumpers, and the rated value of the generator terminal voltage can be set through the setting value in the rotor grounding protection device.

[0062] The linkage communication module is the core module of this optimization direction. It adopts a Modbus / Profinet dual-protocol compatible design, is configured with independent communication interfaces and communication chips, and realizes bidirectional wired communication with the DC insulation detection device and the generator excitation system. The communication baud rate is 9600bps, and the communication delay is ≤5ms. Its specific functions are as follows: 1. Linkage with DC insulation detection device: Receives protection activation / deactivation control signals from the protection activation / deactivation control module and synchronously sends operating mode switching instructions to the DC insulation detection device; includes high-precision detection mode instructions and conventional detection mode instructions, with the instructions accompanied by operating condition identification results and timestamps, ensuring accurate linkage between the operating modes of the DC insulation detection device and the rotor grounding protection device.

[0063] 2. Data interaction with the generator excitation system: Real-time acquisition of the excitation command signal (DC excitation / residual voltage excitation) and the effective value of the excitation current from the excitation system. Operating data such as the working status (normal / fault) of the excitation system are filtered and validated before being transmitted to the operating condition judgment module as an auxiliary criterion for operating condition judgment. At the same time, the operating condition identification results of the device are sent to the excitation system to realize two-way data interaction.

[0064] 3. Communication fault self-detection: The built-in communication fault detection unit monitors the communication link status with the DC insulation detection device and excitation system in real time. When communication is interrupted or the data packet loss rate is greater than 1%, a communication fault alarm is immediately triggered, and the fault information is transmitted to the data upload and remote control unit.

[0065] 7. Data Upload and Remote Control Unit: Utilizing the power plant's standard communication protocol, it communicates with the power plant's DCS / PLC backend monitoring system and also maintains bidirectional signal connections with various modules within the unit. Its core functions are divided into two parts: data upload and remote control. 1. Data Upload: The system collects operating data from each module within the device at 100ms intervals, including DC excitation contact status, effective value of terminal voltage, setting threshold, operating condition identification results, protection activation / deactivation status, module operating status, relay status, communication link status, fault information, etc. The data is packaged, encrypted, and then uploaded to the power plant's backend monitoring system. It supports local data storage (storage period ≥ 6 months) and backend retrieval.

[0066] 2. Remote Control: Receives remote control commands from the power plant's back-end monitoring system, including remote voltage threshold setting commands, remote protection mode switching commands (automatic / manual), remote device parameter configuration commands, and fault reset commands. After verifying the validity of the commands, they are transmitted to the corresponding modules for execution. Simultaneously, the command execution results are fed back to the back-end monitoring system, realizing remote intelligent operation and maintenance of the equipment. The operation permissions of the local human-machine interface and the remote control unit can be set hierarchically to avoid accidental operation.

[0067] When implementing a rotor grounding protection anti-interference method that combines dual identification of operating conditions, the following steps are added: multi-device linkage control, multi-system data interaction, and remote intelligent operation and maintenance. S0 Terminal Voltage Judgment Threshold Setting The generator parameter adaptive configuration module reads basic parameters such as rated capacity $P_N$, rated voltage $U_N$, and excitation curve. It retrieves historical excitation operation data (≥30 sets of valid data) from the power plant's DCS system for the past 6 months. The terminal voltage judgment threshold $U_{set}$ (5%~15%$U_N$) is dynamically adjusted using a fuzzy inference model. It supports both local manual calibration and remote calibration from the power plant's backend. The calibrated $U_{set}$ is sent to the operating condition judgment module, protection activation / deactivation control module, and data upload and remote control unit for storage and uploading.

[0068] S1 Multi-source signal acquisition and transmission 1.1 The DC excitation contact detection module detects the status of the auxiliary contacts of the DC excitation contactor in real time with a sampling interval of 10ms and outputs a digital contact status signal; the generator terminal voltage acquisition module continuously acquires the three-phase voltage signal at the generator terminal, and after processing, outputs the effective value of the voltage at the computer terminal. ; connect the contact status signal and The data is transmitted to the operating condition judgment module and the protection activation / deactivation control module.

[0069] 1.2 The linkage communication module acquires the excitation command and effective value of the excitation current of the generator excitation system in real time. Auxiliary data such as the operating status of the excitation system are filtered and validated before being transmitted to the operating condition judgment module as auxiliary criteria for judging the operating condition.

[0070] 1.3 Each module transmits its own operating status signals to the data upload and remote control unit in real time, where they are collected and preliminarily processed.

[0071] S2 Multi-criteria Operating Condition Subdivision Identification + Pre-Switch Preparation 2.1 The operating condition judgment module receives contact status signals. Combined with excitation system auxiliary data The system performs multiple criteria, three consecutive sampling confirmations, and multi-condition subdivision identification: it verifies the consistency between the excitation system's excitation command and the DC excitation contact status, and verifies the correlation between the excitation current change trend and the terminal voltage change trend. After the verification is passed, the operating conditions are subdivided according to the established rules, and the specific operating condition identification results are output and transmitted to the protection activation / deactivation control module, the linkage communication module, and the data upload and remote control unit.

[0072] 2.2 Calculation of the pre-switching control unit of the protection activation / deactivation control module and The proportion of the difference ΔU, if This triggers the hardware circuit pre-switching preparation, placing the hardware relay in the target deployment / retreat state into the standby state.

[0073] S3 Differentiated protection activation / deactivation + multi-device linkage control 3.1 The protection activation / deactivation control module executes differentiated protection activation / deactivation strategies based on the operating condition identification results: the rotor grounding protection device is deactivated during the initial stage of DC excitation / mid-stage of voltage buildup; a soft activation strategy is adopted during the critical period of excitation completion; and the rotor grounding protection device is normally activated during non-DC excitation operating conditions. The main and backup redundant modules perform real-time mutual checks, the dual relay parallel circuit performs hardware control, and the relay status monitoring unit provides real-time fault alarms.

[0074] 3.2 The linkage communication module synchronously receives protection activation / deactivation control signals and operating condition identification results, and sends a working mode switching command to the DC insulation detection device: When the rotor grounding protection device is deactivated, a high-precision detection mode command is sent to trigger the DC insulation detection device to increase the sampling frequency and lower the detection threshold, and enter the high-precision detection mode of rotor winding insulation, which is fully responsible for insulation detection. When the rotor grounding protection device is activated, a normal detection mode command is sent to trigger the DC insulation detection device to restore the normal sampling frequency and detection threshold, so as to avoid parallel interference with the rotor grounding protection device.

[0075] 3.3 After the rotor grounding protection device is put into operation, the protection principle is selected according to the preset value or remote command, the rotor winding insulation to ground is detected, and an alarm / trip signal is immediately output when a fault is detected. The fault signal is also transmitted synchronously to the linkage communication module and the data upload and remote control unit.

[0076] S4 seamless switching + multi-system data interaction + fault alarm 4.1 When the operating condition changes, the protection is switched on and off seamlessly based on the pre-switching preparation state, with an overall switching delay of ≤10ms. The operating condition switching result is synchronously sent to the DC insulation detection device and the generator excitation system by the linkage communication module to realize the synchronization of operating condition information of multiple systems.

[0077] 4.2 Data Upload and Remote Control Unit: The data upload and remote control unit transmits the status of the DC excitation contacts within the device at 100ms intervals. , All data, including operating condition identification results, protection activation / deactivation status, excitation system auxiliary data, module operating status, and fault information, are encrypted and uploaded to the power plant's back-end monitoring system to achieve real-time data monitoring.

[0078] 4.3 If the device experiences module failure, relay failure, communication failure, protection action, or other issues, the data upload and remote control unit will immediately upload the fault information to the background monitoring system with high priority, and simultaneously trigger a local audible and visual alarm. The fault information includes the fault type, fault location, and fault occurrence timestamp.

[0079] S5 Remote Intelligent Operation and Maintenance 5.1 The power plant's back-end monitoring system can send remote control commands to the data upload and remote control unit according to the unit's operating requirements. These commands include remote voltage threshold setting, automatic / manual mode switching for protection activation / deactivation, remote configuration of device parameters, and fault reset. After the commands are verified for validity, they are executed by the corresponding modules, and the execution results are fed back to the back-end in real time.

[0080] 5.2 When the device is in remote manual mode, the operation and maintenance personnel can directly control the rotor grounding protection device to be turned on or off through the background monitoring system, which is suitable for special working conditions such as unit maintenance and fault handling; when the unit resumes normal operation, it can be switched back to automatic mode, and the device will automatically turn on or off the protection according to the working conditions.

[0081] 5.3 Data Upload and Remote Control Unit: All remote control commands and execution results are logged. The log information is stored locally and can be uploaded to the backend to enable operation traceability.

Claims

1. A rotor grounding protection anti-interference device combining dual identification of operating conditions, characterized in that, It includes a rotor grounding protection device, a DC excitation contact detection module, a generator terminal voltage acquisition module, an operating condition judgment module, and a protection activation / deactivation control module; The DC excitation contact detection module is connected to the separate input channel of the rotor grounding protection device to detect the engagement status of the auxiliary contacts of the DC excitation contactor and output the contact status signal. The generator terminal voltage acquisition module is signal-connected to the operating condition judgment module. It is used to acquire the three-phase voltage signal at the generator terminal, calculate the effective value of the voltage at the generator terminal, and then output it to the operating condition judgment module. The operating condition judgment module is connected to the DC excitation contact detection module and the terminal voltage acquisition module respectively, and is used to receive contact status signals and the effective value of terminal voltage and perform operating condition judgment. The protection activation / deactivation control module is connected to the operating condition judgment module and the rotor grounding protection device, respectively. It is used to output control signals based on the judgment result of the operating condition judgment module to control the activation / deactivation status of the rotor grounding protection device. The rotor grounding protection device is compatible with both injection-type and ping-pong-type rotor grounding protection principles. It is used to detect the insulation resistance of the rotor winding to ground and output a protection action signal.

2. The rotor grounding protection anti-interference device combining dual identification of operating conditions according to claim 1, characterized in that, The DC excitation contact detection module has a separate input channel with opto-isolation design, and the input voltage is compatible with DC 110V / 220V systems. The input channel is also equipped with a hardware filtering circuit.

3. The rotor grounding protection anti-interference device combining dual identification of operating conditions according to claim 1, characterized in that, The aforementioned terminal voltage acquisition module receives the terminal voltage signal through a three-phase voltage transformer. It is internally equipped with voltage divider resistors, filter circuits, and analog-to-digital converter chips. The module's sampling frequency is not less than 1kHz, and the voltage measurement error does not exceed ±1%.

4. The rotor grounding protection anti-interference device combining dual identification of operating conditions according to claim 1, characterized in that, The protection activation / deactivation control module adopts a dual control mechanism of "hardware control + software interlocking". On the hardware side, the core power supply or sampling circuit of the rotor grounding protection device is controlled through relay contacts. On the software side, the protection output is interlocked through the internal logic of the rotor grounding protection device.

5. The rotor grounding protection anti-interference device combining dual identification of operating conditions according to claim 1, characterized in that, The device is compatible with both 110V and 220V DC excitation power supply systems, and the voltage level can be switched via hardware jumpers; the rated value of the generator terminal voltage can be set by the setting value in the rotor grounding protection device.

6. The rotor grounding protection anti-interference device combining dual identification of operating conditions according to claim 1, characterized in that, The device also includes a unit parameter adaptive configuration module, which is signal-connected to the operating condition judgment module. It is used to read the generator's rated capacity, voltage level, excitation curve parameters and retrieve the unit's historical excitation operation data. It dynamically adjusts the generator terminal voltage judgment threshold through a fuzzy algorithm. The adjustment range is 5%-15% of the rated voltage, and manual calibration of the threshold is supported. The operating condition judgment module has built-in multi-operating condition subdivision identification logic, which subdivides the DC excitation operating condition into the initial excitation stage, the middle stage of voltage build-up, and the critical period of excitation completion, and subdivides the non-DC excitation operating condition into the residual voltage excitation operating condition, the normal operation operating condition, and the shutdown standby operating condition.

7. The rotor grounding protection anti-interference device combining dual identification of operating conditions according to claim 1, characterized in that, The protection activation / deactivation control module is equipped with a redundant backup unit and a pre-switching control unit. The redundant backup unit has a dual-module architecture, with the main and backup modules synchronously receiving signals from the operating condition judgment module and synchronizing their operating status in real time. When the main module fails, the backup module switches over without disturbance. The pre-switching control unit is used to monitor the difference between the terminal voltage and the set threshold in real time. When the difference is within the preset range, the hardware circuit of the target activation / deactivation state is placed in the standby state. The hardware control circuit of the protection activation / deactivation control module adopts a dual-relay parallel design and is equipped with a relay status real-time monitoring unit. When a relay fails, an alarm signal is triggered immediately.

8. The rotor grounding protection anti-interference device combining dual identification of operating conditions according to claim 1, characterized in that, The device also includes a linkage communication module and a data upload and remote control unit. The linkage communication module adopts the Modbus / Profinet industrial standard communication protocol and is bidirectionally connected to the DC insulation detection device and the generator excitation system, respectively, to realize the linkage of working modes with the DC insulation detection device and the interaction of operating data with the excitation system. The data upload and remote control unit is connected to the power plant's background monitoring system and is also connected to the signals of each module in the device. It is used to collect the device's operating data and upload it to the background monitoring system, while receiving remote control commands from the background system to realize the setting of device parameters and the switching of protection activation and deactivation modes.

9. A method for using a rotor grounding protection anti-interference device combining dual operating condition identification as described in any one of claims 1-8, characterized in that, Includes the following steps: Step 1: After the unit starts, the DC excitation contact detection module detects the status of the auxiliary contact of the DC excitation contactor in real time and outputs the contact status signal. The generator terminal voltage acquisition module continuously acquires the three-phase voltage signal of the generator terminal and calculates the effective value of the voltage at the computer terminal, and transmits both to the operating condition judgment module. Step 2: The operating condition judgment module performs dual operating condition judgment based on the connection point status signal and the effective value of the terminal voltage: If the DC excitation connection is in the engaged state and the effective value of the terminal voltage is lower than 10% of the rated voltage, it is judged as the DC excitation incomplete operating condition; if the DC excitation connection is in the disengaged state, or the effective value of the terminal voltage is higher than 10% of the rated voltage, it is judged as the non-DC excitation operating condition or the DC excitation completed operating condition. Step 3: The protection activation / deactivation control module outputs control signals based on the operating condition judgment results to control the activation / deactivation of the rotor grounding protection device: if it is determined that the DC excitation is not completed, the rotor grounding protection device is deactivated; if it is determined that the non-DC excitation is completed or the DC excitation is completed, the rotor grounding protection device is activated, and the rotor winding insulation to ground detection and protection action logic are executed. Step 4: Monitor the status of the DC excitation contact and the changes in the terminal voltage in real time. When the operating conditions change, the protection activation / deactivation control module will synchronously switch the activation / deactivation status of the rotor grounding protection device, and the switching delay will not exceed 100ms.

10. The rotor grounding protection anti-interference method combining dual identification of operating conditions according to claim 9, characterized in that, In Step 3, when the rotor grounding protection device is deactivated, the protection activation / deactivation control module uses a dual mechanism of "hardware control + software interlock" to disconnect the hardware contacts and interlock the protection output of the rotor grounding protection device in software; when the rotor grounding protection device is activated, the hardware contacts are closed and the protection output of the rotor grounding protection device is unlocked in software.

11. The rotor grounding protection anti-interference method combining dual identification of operating conditions according to claim 9, characterized in that, In Step 3, after the rotor grounding protection device is put into operation, it selects either injection-type or ping-pong-type protection principle according to the preset value. Through the process of signal injection, grounding detection, and fault judgment, it realizes the rotor winding insulation to ground detection. If a fault is detected, it outputs an alarm or trip protection action signal.

12. The rotor grounding protection anti-interference method combining dual identification of operating conditions according to claim 9, characterized in that, Before Step 1, there is also a voltage threshold adaptive setting step: the generator rated capacity, voltage level, and excitation curve parameters are read by the unit parameter adaptive configuration module, the generator terminal voltage change pattern at the completion of DC excitation is retrieved from the historical excitation operation data of the unit, the generator terminal voltage judgment threshold is dynamically set by fuzzy algorithm and sent to the operating condition judgment module. The threshold setting range is 5%-15% of the rated voltage, and manual calibration is also supported. In Step 2, the operating condition judgment module performs multi-operating condition subdivision identification. Combining the DC excitation contact status and the set generator terminal voltage threshold, the DC excitation operating condition is subdivided into the initial excitation stage, the middle voltage build-up stage, and the critical period of excitation completion. The non-DC excitation operating condition is subdivided into the residual voltage excitation operating condition, the normal operation operating condition, and the shutdown standby operating condition. In Step 3, the protection activation / deactivation control module executes differentiated protection activation / deactivation strategies for different subdivision operating conditions. For the critical period of excitation completion, a soft protection activation strategy is adopted, which first unlocks the software lockout, delays for 50ms, and then closes the hardware contact.

13. The rotor grounding protection anti-interference method combining dual identification of operating conditions according to claim 9, characterized in that, Before outputting the operating condition judgment result, the Step 2 operating condition judgment module first determines whether the difference between the terminal voltage and the set threshold is within the preset range. If so, it triggers the hardware circuit pre-switching preparation and puts the hardware relay of the target enabling / disabling state into the energized / disengaged ready-to-operate state. When the operating condition changes in Step 4, the protection enabling / disabling seamless switching is achieved based on the pre-switching preparation state. During the operation of the protection enabling / disabling control module, the main and backup redundant modules mutually check the operating status in real time. When the main module fails, the backup module takes over the control without disturbance. The dual relay parallel circuit synchronously monitors the operating status. When a single relay fails, an alarm is immediately triggered and the other relay maintains the control function.

14. The rotor grounding protection anti-interference method combining dual identification of operating conditions according to claim 9, characterized in that, In Step 3, while the protection activation / deactivation control module outputs the protection activation / deactivation control signal, the linkage communication module sends a mode switching command to the DC insulation detection device. When the rotor grounding protection device is deactivated, the DC insulation detection device is triggered to enter the high-precision detection mode. When the rotor grounding protection device is activated, the DC insulation detection device is triggered to return to the normal detection mode. The linkage communication module simultaneously collects the excitation command and excitation current signal from the generator excitation system as auxiliary criteria for the operating condition judgment module. The operating status, operating condition judgment results, protection activation / deactivation status, and fault information of each module in the device are uploaded in real time to the power plant's background monitoring system by the data upload and remote control unit. It also supports remote setting of voltage thresholds and switching between automatic and manual modes for protection activation / deactivation.

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