Relay protection longitudinal differential protection synchronous verification method

Abstract

The invention provides a relay protection longitudinal differential protection synchronous verification method, which comprises the following steps of: establishing tester connection on two sides through double-link redundant communication, and measuring physical and communication time delay and dynamically compensating a phase by combining high-frequency pulse; setting parameters based on the protection device characteristic database, and issuing the parameters after encryption verification; a signal is generated through a phase locking loop and an amplitude closed-loop controller, and local sampling feedback errors and iterative correction are carried out; a safety interlocking mechanism is introduced to ensure verification safety, and a multi-terminal network scene is supported. The problems that a traditional method is low in synchronization precision, weak in interference resistance and low in efficiency are solved, the amplitude error is smaller than or equal to 0.1%, the phase error is smaller than or equal to 0.1%, the verification efficiency is improved by more than 10 times, and the method is suitable for automatic verification of various longitudinal differential protection devices.

Description

Technical Field

[0001] This invention relates to the field of power system relay protection technology, specifically to a method for synchronous verification of longitudinal differential protection of relay protection. Background Technology

[0002] In the periodic testing and commissioning verification of longitudinal differential protection for transmission lines, it is usually necessary to simultaneously apply three-phase analog quantities to the relay protection devices at both ends of the line to simulate normal operation and fault conditions. In the existing technology, the analog quantity input of the relay protection devices at both ends of the line mostly relies on manual adjustment of the testing instrument to ensure that the amplitude, phase and initial phase angle of the three-phase signals are strictly consistent. This is labor-intensive, difficult to control errors, and inefficient.

[0003] In the line protection commissioning experiment, the relay protection tester outputs a three-phase sinusoidal AC quantity. Taking phase A current as an example: ;

[0004] Under normal operating conditions, the current collected by the relay protection devices on both sides of the line is exactly the same. This requires that when calibrating the relay protection devices, in order to simulate normal operating conditions, both sides need to input the same analog quantity at the same time (if the current frequency is 50Hz, the time must be accurate to within 5ms (a quarter cycle)). The existing manual input has large errors, low efficiency, weak anti-interference ability during implementation, and is not safe enough. It cannot be input synchronously, resulting in a low success rate of the experiment. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a method for synchronous verification of longitudinal differential protection of relay protection. Through dynamic time delay compensation, anti-interference communication, intelligent parameter optimization, multi-terminal adaptation and safety interlocking, the method can realize high-precision, high-efficiency and high-reliability verification of longitudinal differential protection device.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for synchronous verification of longitudinal differential protection of relay protection includes: A unified parameter setting module is configured on the relay protection test instrument to set the target amplitude, phase and initial phase angle of the three-phase signal; The relay protection test instruments on both sides of the line establish communication links through the communication network; The signal generation unit of the relay protection test instrument on both sides has a built-in phase-locked loop (PLL) and amplitude feedback controller, which are used to automatically generate the corresponding three-phase analog signals after receiving the parameters from the other side; The relay protection test instrument on both sides performs time verification through network communication; Once the time verification is consistent, adjust the output of the relay protection testers on both sides to make them consistent, and set the initial time. Press the start button, and after the initial time is reached, the relay protection test instruments on both sides will start input simultaneously.

[0007] The relay protection testers on both sides of the aforementioned line establish a communication connection through a communication network. This communication connection includes: The relay protection testers on both sides of the line establish a communication connection through a dual-link redundant communication architecture, which includes a main link and a backup link. The main link uses a 5G network, and the backup link uses a dedicated fiber optic network.

[0008] The aforementioned dual-link redundant communication architecture also includes a link quality monitoring module. This module monitors the packet loss rate and latency jitter of the primary link and the backup link in real time. When the packet loss rate of the primary link exceeds a set value or the latency jitter exceeds a set value, it automatically switches to the backup link.

[0009] The aforementioned relay protection testers on both sides perform time verification via network communication, including time synchronization and time delay measurements, including: The same time synchronization server is used to synchronize the network time of the relay protection testers on both sides. At the same time, high-frequency synchronization pulses are transmitted back and forth between the two testers to calculate the total time delay of the physical line and the communication network in real time. .

[0010] After pressing the start button and reaching the initial time, the unified parameter setting module sets and distributes parameters to the relay protection tester, including: Using a relay protection tester on one side as the master station, the target parameters of the three-phase signal are set according to the test requirements. The target parameters include amplitude A, phase ω, and initial phase angle φ. The target parameters are then sent to the slave station tester on the other side through an encryption verification mechanism. The encryption verification mechanism includes CRC cyclic redundancy check and digital signature. The target parameters are encrypted and verified before being transmitted through the communication link.

[0011] The above-mentioned synchronous verification method is as follows: Step 1: Communication Connection; The relay protection test instruments on both sides of the line communicate with each other using a communication network. Step 2: Time synchronization; synchronize the relay protection test instruments on both sides via network time synchronization; Step 3: Connect the test leads; connect the analog input interfaces of the relay protection test instrument on both sides to the input ports of the relay protection device; Step 4: Parameter distribution; Taking one side as a reference, set the three-phase signal parameters according to the test requirements: amplitude A, phase ω, initial phase angle φ, and distribute them to the relay protection test instrument on the other side through the communication interface; Step 5, Output; After receiving the parameter information, the relay protection test instrument on the other side drives the output module according to the parameters { Generate three-phase AC analog signals and start the initial output; Step 6: Sampling and feedback; the local sampling module on the other side measures the actual amplitude of the output signal. With phase Return to the initial side; Step 7: Error Correction; The error calculation module compares the returned data with the target value and calculates the error. It sends correction commands to its own output module and the other side tester through a feedback algorithm, driving its phase-locked loop (PLL) and amplitude closed-loop control to adjust the output. Step 8, Synchronous Startup; when and Once all values ​​are less than the preset threshold, a "start test" signal is simultaneously sent to trigger the relay protection devices at both ends to perform longitudinal differential action verification.

[0012] The error correction in Step 7 above adopts dynamic error correction. The master station calculates the phase compensation value Δφ = ω·τ based on the total delay τ, and calculates the amplitude error ΔA and the phase error Δφ' by combining the actual amplitude A' and the actual phase φ' transmitted back. The correction command is issued to the output modules of the master station and the slave station through the feedback algorithm to adjust the output of the phase-locked loop and the amplitude closed-loop controller.

[0013] When the above-mentioned lines have 3 or more terminals, a star-mesh hybrid synchronous architecture is adopted, with the master station as the core node. The clock of the multi-terminal testers is made consistent through the IEEE 1588 PTP precise time protocol. Substations exchange local error data through neighbor communication and use a weighted average consistency algorithm to adjust the output collaboratively.

[0014] The above method also includes a safety interlocking step: real-time acquisition of the "trip output pressure plate status" and "operation mode signal" of the relay protection device, and signal injection is initiated only when the device is in "verification mode" and the "trip output pressure plate is deactivated"; real-time monitoring of the differential current I on both sides. 差 =I 主站 -I 从站 , when I 差 The signal output will be immediately interrupted if the rated current exceeds the set ratio.

[0015] The signal generation unit of the aforementioned slave tester is also equipped with a noise suppression filter, which is a second-order Butterworth low-pass filter used to reduce the interference of high-frequency electromagnetic noise on the analog signal output.

[0016] The frequency of the aforementioned high-frequency synchronization pulse is 1MHz. The two test instruments use built-in pulse transceiver modules to transmit and receive the high-frequency synchronization pulse.

[0017] The above target parameters are set based on the protection device characteristic database, which pre-stores the input characteristics of different types of relay protection devices, including linearity, response time, and error-sensitive frequency band. The master station matches the optimal initial parameters according to the current verification device model.

[0018] The above method also includes a parameter self-optimization step: after each verification, the error convergence curve is recorded, and the feedback correction coefficient is iteratively optimized through a reinforcement learning algorithm. The feedback correction coefficient includes the phase-locked loop phase-locked speed and the PID parameters of the amplitude closed-loop controller.

[0019] The method for synchronous verification of longitudinal differential protection of relay protection mentioned in this invention has the following beneficial effects: 1. Significantly improved synchronization accuracy: Through dynamic delay compensation and high-frequency pulse measurement, the phase error is controlled within 0.1°, solving the synchronization deviation problem caused by long-distance transmission delay; 2. Enhanced anti-interference capability: Dual-link redundant communication + encryption verification mechanism ensures parameter transmission reliability of 99.99% and packet loss rate ≤0.01%; 3. Enhanced intelligence and adaptability: Based on database and reinforcement learning, parameters are self-optimized to adapt to the characteristics of different devices, reducing the verification efficiency from tens of minutes to within 5 seconds; 4. More comprehensive scenario coverage: Supports verification of two-end and multi-end power transmission networks, and automatically switches synchronization strategies based on dynamic topology identification; 5. Enhanced safety: The safety interlocking mechanism prevents malfunctions of protection devices during the verification process, ensuring the safe operation of the power grid. Attached Figure Description The present invention will be further described below with reference to the accompanying drawings and embodiments: Figure 1 A schematic diagram of the relay protection device in normal operation; Figure 2 A schematic diagram for verifying relay protection devices during power outages on existing lines; Figure 3 This is a schematic diagram of the connection of the synchronous verification method for longitudinal differential protection of relay protection according to the present invention. Detailed Implementation

[0020] The technical solution of the present invention will be described in detail below with reference to the accompanying drawings and embodiments.

[0021] A method for synchronous verification of longitudinal differential protection of relay protection includes: A unified parameter setting module is configured on the relay protection test instrument to set the target amplitude, phase and initial phase angle of the three-phase signal; The relay protection test instruments on both sides of the line establish communication links through the communication network; The signal generation unit of the relay protection test instrument on both sides has a built-in phase-locked loop (PLL) and amplitude feedback controller, which are used to automatically generate the corresponding three-phase analog signals after receiving the parameters from the other side; The relay protection test instrument on both sides performs time verification through network communication; Once the time verification is consistent, adjust the output of the relay protection testers on both sides to make them consistent, and set the initial time. Press the start button, and after the initial time is reached, the relay protection test instruments on both sides will start input simultaneously.

[0022] The relay protection testers on both sides of the aforementioned line establish a communication connection through a communication network. This communication connection includes: The relay protection testers on both sides of the line establish a communication connection through a dual-link redundant communication architecture, which includes a main link and a backup link. The main link uses a 5G network, and the backup link uses a dedicated fiber optic network.

[0023] The aforementioned dual-link redundant communication architecture also includes a link quality monitoring module. The link quality monitoring module detects the packet loss rate and latency jitter of the main link and the backup link in real time. When the packet loss rate of the main link is greater than a set value (>0.01%) or the latency jitter is set value (>0.5ms), it automatically switches to the backup link.

[0024] The aforementioned relay protection testers on both sides perform time verification via network communication, including time synchronization and time delay measurements, including: The same time synchronization server is used to synchronize the network time of the relay protection testers on both sides. At the same time, high-frequency synchronization pulses are transmitted back and forth between the two testers to calculate the total time delay of the physical line and the communication network in real time. .

[0025] The round-trip transmission of high-frequency synchronization pulses between the two testing instruments can be achieved through wireless communication technology, satellite communication technology, and network-based time synchronization protocols. Wireless communication technology: Utilizing the high speed and low latency characteristics of networks such as 5G to transmit high-frequency synchronization pulses. The air interface latency of 5G networks can be as low as 1 millisecond, meeting pulse transmission requirements under certain precision conditions. 5G communication modules are configured on both sides of the test equipment to modulate the high-frequency synchronization pulses into the 5G signal for transmission. Because 5G networks employ technologies such as massive MIMO and millimeter waves, the reliability and stability of signal transmission are high, ensuring the accuracy of pulses during long-distance transmission and reducing transmission loss and interference caused by distance.

[0026] Satellite communication technology: Utilizing satellites as relay stations, signal transmission between the testing instruments on both sides is achieved. Satellite communication has a wide coverage area and is not limited by geographical distance. Each testing instrument is equipped with a satellite communication terminal, converting high-frequency synchronization pulses into a signal format that can be transmitted by the satellite, and then transmitting the signal back and forth via satellite relay. For example, the satellite communication system of the International Telecommunication Union (ITU) can provide communication services to users worldwide. Although satellite communication has a certain transmission delay, this delay can be corrected through precise time measurement and compensation algorithms, thus meeting the requirements for synchronization pulse transmission.

[0027] The network time synchronization protocol combines network transmission: it adopts a network-based time synchronization protocol such as IEEE 1588 Precision Time Protocol (PTP). In the network accessed by both test instruments, a PTP master clock and slave clock are set, with both test instruments acting as slave clocks. The test instruments exchange time information over the network according to the PTP protocol to achieve high-precision time synchronization. Based on this synchronization, both test instruments generate and send high-frequency synchronization pulses, which are transmitted using the network link. Because network link construction is relatively flexible, leased lines or existing communication network resources can be used, ensuring pulse transmission reachability even over long distances.

[0028] After pressing the start button and reaching the initial time, the unified parameter setting module sets and distributes parameters to the relay protection tester, including: Using a relay protection tester on one side as the master station, the target parameters of the three-phase signal are set according to the test requirements. The target parameters include amplitude A, phase ω, and initial phase angle φ. The target parameters are then sent to the slave station tester on the other side through an encryption verification mechanism. The encryption verification mechanism includes CRC cyclic redundancy check and digital signature. The target parameters are encrypted and verified before being transmitted through the communication link.

[0029] The above-mentioned synchronous verification method is as follows: Step 1: Communication Connection; The relay protection test instruments on both sides of the line communicate with each other using a communication network. Step 2: Time synchronization; synchronize the relay protection test instruments on both sides via network time synchronization; Step 3: Connect the test leads; connect the analog input interfaces of the relay protection test instrument on both sides to the input ports of the relay protection device; Step 4: Parameter distribution; Taking one side as a reference, set the three-phase signal parameters according to the test requirements: amplitude A, phase ω, initial phase angle φ, and distribute them to the relay protection test instrument on the other side through the communication interface; Step 5, Output; After receiving the parameter information, the relay protection test instrument on the other side drives the output module according to the parameters { Generate three-phase AC analog signals and start the initial output; Step 6: Sampling and feedback; the local sampling module on the other side measures the actual amplitude of the output signal. With phase Return to the initial side; Step 7: Error Correction; The error calculation module compares the returned data with the target value and calculates the error. It sends correction commands to its own output module and the other side tester through a feedback algorithm, driving its phase-locked loop (PLL) and amplitude closed-loop control to adjust the output. Step 8, Synchronous Startup; when and When both values ​​are less than the preset thresholds such as 0.1% and 0.1°, a "start test" signal is sent simultaneously to trigger the relay protection devices at both ends to perform longitudinal differential action verification.

[0030] The error correction in Step 7 above adopts dynamic error correction. The master station calculates the phase compensation value Δφ = ω·τ based on the total delay τ, and calculates the amplitude error ΔA and the phase error Δφ' by combining the actual amplitude A' and the actual phase φ' transmitted back. The correction command is issued to the output modules of the master station and the slave station through the feedback algorithm to adjust the output of the phase-locked loop and the amplitude closed-loop controller.

[0031] When the above-mentioned lines have 3 or more terminals, a star-mesh hybrid synchronous architecture is adopted, with the master station as the core node. The clock of the multi-terminal testers is made consistent through the IEEE 1588 PTP precise time protocol. Substations exchange local error data through neighbor communication and use a weighted average consistency algorithm to adjust the output collaboratively.

[0032] The above method also includes a safety interlocking step: real-time acquisition of the "trip output pressure plate status" and "operation mode signal" of the relay protection device, and signal injection is initiated only when the device is in "verification mode" and the "trip output pressure plate is deactivated"; real-time monitoring of the differential current I on both sides. 差 =I 主站 -I 从站 , when I 差If the current exceeds the set ratio of the rated current, for example, by 5%, the signal output will be immediately interrupted.

[0033] The signal generation unit of the aforementioned slave tester is also equipped with a noise suppression filter, which is a second-order Butterworth low-pass filter used to reduce the interference of high-frequency electromagnetic noise on the analog signal output.

[0034] The frequency of the aforementioned high-frequency synchronization pulse is 1MHz. The two test instruments use built-in pulse transceiver modules to transmit and receive the high-frequency synchronization pulse.

[0035] The above target parameters are set based on the protection device characteristic database, which pre-stores the input characteristics of different types of relay protection devices, including linearity, response time, and error-sensitive frequency band. The master station matches the optimal initial parameters according to the current verification device model.

[0036] The above method also includes a parameter self-optimization step: after each verification, the error convergence curve is recorded, and the feedback correction coefficient is iteratively optimized through a reinforcement learning algorithm. The feedback correction coefficient includes the phase-locked loop phase-locking speed and the PID parameters of the amplitude closed-loop controller.

[0037] Example 1: like Figure 1 The diagram shows the principle of the line during normal operation. During normal operation, the power flow direction of the power grid is M→N. At the same time, the currents collected by the current transformers on the M side and the N side are exactly the same. The relay protection devices on the M side and the N side communicate through optical fiber and compare the current values ​​collected on both sides. When they are inconsistent, it indicates that a line fault has occurred, and the protection will operate and trip the circuit breaker.

[0038] like Figure 2 The diagram shown is an electrical schematic for verifying relay protection devices in existing technical solutions. A relay protection tester is used to input analog quantities. Since the power grid frequency is 50Hz, the input to the relay protection tester is a sinusoidal AC quantity with a cycle of 20ms. M and N are far apart. During joint debugging, it is difficult to manually ensure that the voltage and current input to the relay protection device from the M and N sides are exactly the same at the same time. It is possible that at time T0, the current on the M side is Ia, while the N side lags behind by half a cycle. In this case, the current input on the N side at time T0 is -Ia. At this time, there is a differential current, and the protection device will operate.

[0039] like Figure 3 The diagram shown is a connection diagram of the relay protection tester during the verification of the relay protection device in this invention. The relay protection testers on the M side and the N side are connected and communicated through a 5G network.

[0040] The diagram above shows the test control master station (relay protection tester), which includes a PLC controller, a three-phase signal generator, a local sampling module, a phase-locked loop and amplitude control circuit, and a communication interface.

[0041] Step 1: Communication Connection: The relay protection testers on both ends of the line, M side and N side, communicate using a 5G network to ensure that the testers are connected correctly.

[0042] Step 2, Time Synchronization: Use the same time synchronization server to synchronize the relay protection testers on both sides to ensure that the time on both sides is synchronized.

[0043] Step 3: Connect the test leads: Connect the analog input interface of the relay protection tester to the input interface of the relay protection device.

[0044] Step 4: Parameter Distribution: Using the M side as the reference, set the three-phase signal parameters according to the test requirements: {amplitude, phase, initial phase angle} ({ The data is transmitted to the N-side tester via the communication interface.

[0045] Step 5, Output: After receiving the information from the M side, the N side drives the output module according to the parameters { Generate three-phase AC analog signals and start the initial output.

[0046] Step Six: Sampling Feedback: The N-side local sampling module measures the actual amplitude of the output signal. With phase The data is sent back to the M side.

[0047] Step 7, Error Correction: The error calculation module compares the returned data with the target value and calculates the error. It sends correction commands to its own output module and N-side test instrument through feedback algorithm, driving its phase-locked loop (PLL) and amplitude closed-loop control to adjust the output.

[0048] Step 8, Synchronous Startup: When and If both values ​​are less than the preset threshold, such as 0.1% and 0.1°, a "start test" signal is sent simultaneously to trigger the relay protection devices at both ends to perform longitudinal differential action verification.

[0049] Implementation 2: Dynamic error correction is employed. Communication connection: The M-side and N-side testers establish dual-link communication through the 5G module and fiber optic interface. The link quality monitoring module detects the 5G link packet loss rate (threshold 0.01%) and latency jitter (threshold 0.5ms) in real time. When the 5G link does not meet the requirements, it automatically switches to the fiber optic link.

[0050] Time synchronization and delay measurement: The M side and the N side are connected to the same IEEE 1588 PTP time synchronization server, with a clock synchronization accuracy of ±10ns; the pulse transceiver module on the M side sends a 1MHz synchronization pulse, which is received by the N side and immediately transmitted back. The round-trip time is recorded as t=20ms, and the total delay is calculated as τ=10ms.

[0051] Parameter setting and distribution: The main station (M side) identifies the current verification device model as "Type A longitudinal differential protection device", matches the optimal parameters from the database: amplitude A=5, phase ω=314rad / s, initial phase angle φ=0°; after the parameters are verified by CRC (verification value 0x1234) and digitally signed, they are distributed to the N side through the 5G link.

[0052] Signal generation and sampling: After receiving parameters on the N side, the PLL locks the phase, and the amplitude closed-loop controller outputs a 5A signal; after noise suppression by a second-order Butterworth low-pass filter (cutoff frequency 1kHz), the local sampling module measures A'=4.998 and φ'=-0.05°, and transmits it back to the M side.

[0053] Error correction: The phase compensation value calculated on the M side is Δφ = 314 × 0.01 = 3.14 rad ≈ 180°, and the phase error Δφ' = | -0.05° + 180° - 0° | = 179.95° (initial deviation). The phase offset of the PLL on the N side is adjusted by +179.95° through the feedback algorithm. After 3 iterations, A' = 5.000A, φ' = -0.08°, ΔA = 0.04%, and Δφ' = 0.02°, which meets the threshold.

[0054] Synchronous verification: A start signal is sent from the M side, and signals are injected simultaneously from both sides; the safety interlock module detects that the device is in "verification mode" and the pressure plate is disengaged, and the differential current I... 差 =0.01A (<5%×5A=0.25A), the verification proceeded normally.

Claims

1. A method for synchronous verification of longitudinal differential protection of relay protection, characterized in that, include; A unified parameter setting module is configured on the relay protection test instrument to set the target amplitude, phase and initial phase angle of the three-phase signal; The relay protection test instruments on both sides of the line establish communication links through the communication network; The signal generation unit of the relay protection test instrument on both sides has a built-in phase-locked loop (PLL) and amplitude feedback controller, which are used to automatically generate the corresponding three-phase analog signals after receiving the parameters from the other side; The relay protection test instrument on both sides performs time verification through network communication; Once the time verification is consistent, adjust the output of the relay protection testers on both sides to make them consistent, and set the initial time. Press the start button, and after the initial time is reached, the relay protection test instruments on both sides will start input simultaneously.

2. The method for synchronous verification of longitudinal differential protection of relay protection according to claim 1, characterized in that, The relay protection testers on both sides of the line establish a communication connection through a communication network. This communication connection includes: The relay protection testers on both sides of the line establish a communication connection through a dual-link redundant communication architecture, which includes a main link and a backup link. The main link uses a 5G network, and the backup link uses a dedicated fiber optic network.

3. The method for synchronous verification of longitudinal differential protection of relay protection according to claim 2, characterized in that, The dual-link redundant communication architecture also includes a link quality monitoring module, which monitors the packet loss rate and latency jitter of the main link and the backup link in real time. When the packet loss rate of the main link exceeds a set value or the latency jitter exceeds a set value, it automatically switches to the backup link.

4. The method for synchronous verification of longitudinal differential protection of relay protection according to claim 3, characterized in that, The aforementioned relay protection testers on both sides perform time verification via network communication, including time synchronization and time delay measurements, including: The same time synchronization server is used to synchronize the network time of the relay protection testers on both sides. At the same time, high-frequency synchronization pulses are transmitted back and forth between the two testers to calculate the total time delay of the physical line and the communication network in real time. .

5. The method for synchronous verification of longitudinal differential protection of relay protection according to claim 4, characterized in that, After the start button is pressed and the initial time is reached, the unified parameter setting module sets and distributes parameters to the relay protection tester, including: Using a relay protection tester on one side as the master station, the target parameters of the three-phase signal are set according to the test requirements. The target parameters include amplitude A, phase ω, and initial phase angle φ. The target parameters are then sent to the slave station tester on the other side through an encryption verification mechanism. The encryption verification mechanism includes CRC cyclic redundancy check and digital signature. The target parameters are encrypted and verified before being transmitted through the communication link.

6. The method for synchronous verification of longitudinal differential protection of relay protection according to claim 4, characterized in that, The method for synchronous verification is as follows: Step 1: Communication Connection; The relay protection test instruments on both sides of the line communicate with each other using a communication network. Step 2: Time synchronization; synchronize the relay protection test instruments on both sides via network time synchronization; Step 3: Connect the test leads; connect the analog input interfaces of the relay protection test instrument on both sides to the input ports of the relay protection device; Step 4: Parameter distribution; Taking one side as a reference, set the three-phase signal parameters according to the test requirements: amplitude A, phase ω, initial phase angle φ, and distribute them to the relay protection test instrument on the other side through the communication interface; Step 5, Output; After receiving the parameter information, the relay protection test instrument on the other side drives the output module according to the parameters { Generate three-phase AC analog signals and start the initial output; Step 6: Sample return; The local sampling module on the other side measures the actual amplitude of the output signal. With phase Return to the initial side; Step 7: Error Correction; The error calculation module compares the returned data with the target value and calculates the error. It sends correction commands to its own output module and the other side tester through a feedback algorithm, driving its phase-locked loop (PLL) and amplitude closed-loop control to adjust the output. Step 8, Synchronous Startup; when and Once all values ​​are less than the preset threshold, a "start test" signal is simultaneously sent to trigger the relay protection devices at both ends to perform longitudinal differential action verification.

7. The method for synchronous verification of longitudinal differential protection of relay protection according to claim 6, characterized in that, The error correction in Step 7 adopts dynamic error correction. The master station calculates the phase compensation value Δφ = ω·τ based on the total delay τ, and calculates the amplitude error ΔA and the phase error Δφ' by combining the actual amplitude A' and the actual phase φ' transmitted back. The correction command is issued to the output modules of the master station and the slave station through the feedback algorithm to adjust the output of the phase-locked loop and the amplitude closed-loop controller.

8. The method for synchronous verification of longitudinal differential protection of relay protection according to claim 7, characterized in that, When the line has 3 or more terminals, a star-mesh hybrid synchronous architecture is adopted, with the master station as the core node. The clock of the multi-terminal testers is made consistent through the IEEE1588 PTP precise time protocol. Substations exchange local error data through neighbor communication and use a weighted average consistency algorithm to adjust the output collaboratively.

9. A method for synchronous verification of longitudinal differential protection of relay protection according to claim 7, characterized in that, The method further includes a safety interlocking step: real-time acquisition of the "trip output pressure plate status" and "operation mode signal" of the relay protection device, and signal injection is initiated only when the device is in "verification mode" and the "trip output pressure plate is deactivated"; real-time monitoring of the differential current I on both sides. 差 =I 主站 -I 从站 , when I 差 The signal output will be immediately interrupted if the rated current exceeds the set ratio.

10. A method for synchronous verification of longitudinal differential protection of relay protection according to claim 9, characterized in that, The signal generation unit of the slave tester is also equipped with a noise suppression filter, which is a second-order Butterworth low-pass filter used to reduce the interference of high-frequency electromagnetic noise on the analog signal output.

11. The method for synchronous verification of longitudinal differential protection of relay protection according to claim 4, characterized in that, The frequency of the high-frequency synchronization pulse is 1MHz, and the two test instruments realize the transmission and reception of the high-frequency synchronization pulse through the built-in pulse transceiver module.

12. The method for synchronous verification of longitudinal differential protection of relay protection according to claim 4, characterized in that, The target parameters are set based on the protection device characteristic database, which pre-stores the input characteristics of different types of relay protection devices, including linearity, response time, and error-sensitive frequency bands. The master station matches the optimal initial parameters according to the current verification device model.

13. The method for synchronous verification of longitudinal differential protection of relay protection according to claim 6, characterized in that, The method further includes a parameter self-optimization step: after each verification, the error convergence curve is recorded, and the feedback correction coefficient is iteratively optimized through a reinforcement learning algorithm. The feedback correction coefficient includes the phase-locked loop phase-locking speed and the PID parameters of the amplitude closed-loop controller.

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