A method for synchronizing differential protection signals in a distribution network system

Abstract

This invention relates to the field of differential protection signal synchronization technology, and more particularly to a method for synchronizing differential protection signals in a distribution network system. Addressing the problems of low success rates due to the single signal synchronization method used in current differential protection signal synchronization technologies, and short synchronization timeliness due to the lack of post-synchronization detection, the invention proposes the following solution, including the following steps: S1: Device preparation; S2: Preliminary calibration; S3: Synchronization sampling; S4: Recalibration; S5: Signal detection; S6: Test comparison. The purpose of this invention is to improve the success rate of signal synchronization by employing multiple signal synchronization methods for signal calibration. Furthermore, by performing signal detection after successful synchronization, it avoids information asynchrony caused by slow synchronization timeliness, thus enhancing the timeliness of signal synchronization.

Description

Technical Field

[0001] This invention relates to the field of differential protection signal synchronization technology, and in particular to a method for synchronizing differential protection signals in a distribution network system. Background Technology

[0002] The basic principle of differential protection is Kirchhoff's law, which states that "the sum of the currents flowing into a node in a circuit is equal to zero." The principle of current differential protection was proposed at the beginning of this century and has been in use for approximately 90 years. Current differential protection is a type of relay protection, widely used as the main protection for generators, transformers, busbars, and large motors in power systems due to its simple and reliable principle. The earliest application of current differential protection in power lines was traditional conductor protection. It can serve as the full-line, high-speed main protection for short-distance lines in high and medium voltage power grids. "Single-line" and "differential" are a pair of concepts. "Single-line" refers to the absolute value, while "differential" refers to the relative value. When the absolute value of the value does not change significantly, single-line input / output should be used. However, when the absolute value changes significantly, using single-line input / output would require a large instrument range, which means lower accuracy. In this case, using differential protection ensures that the controlled quantity remains within a relatively small range, thus achieving higher control accuracy.

[0003] However, the existing differential protection signal synchronization technology uses a single signal synchronization method, resulting in a low success rate of signal synchronization, and the lack of detection after successful signal synchronization leads to a short signal synchronization timeliness. Therefore, we propose a differential protection signal synchronization method for distribution network systems to solve the above problems. Summary of the Invention

[0004] The purpose of this invention is to solve the problems of low success rate of signal synchronization due to the single signal synchronization method used in the existing differential protection signal synchronization technology, and short signal synchronization time due to the lack of detection after successful signal synchronization. Therefore, this invention proposes a differential protection signal synchronization method for distribution network systems.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for synchronizing differential protection signals in a distribution network system includes the following steps:

[0007] S1: Equipment preparation: Prepare the equipment required for signal synchronization;

[0008] S2: Preliminary correction: Preliminary signal correction is performed using the sampled data correction method;

[0009] S3: Synchronous sampling: The protection devices on both sides of the line are sampled synchronously by adjusting the sampling time.

[0010] S4: Recalibrate: Perform signal recalibration using the clock calibration method;

[0011] S5: Signal Detection: GPS is used to detect the signals at both ends after signal synchronization, and the detection results are used for judgment and processing;

[0012] S6: Test and Comparison: Test the differential protection signal synchronization method of the distribution network system and compare it with existing methods;

[0013] Preferably, in S1, a distribution network system is established, wherein the system includes a 5G network, optical fiber and GPS, and 5G base stations are established manually at equal intervals and intermittently, 5G channels are established through the base stations, and signals are transmitted through the 5G channels.

[0014] Preferably, in S2, the sampling data correction method is used for preliminary signal correction. When the sampling data correction method is used, the two protections are not distinguished as master and slave. Each protection is controlled by its own crystal oscillator and samples independently at the same sampling frequency. Each frame of data sent contains time stamp information and current sampling data information. The current sampling data is the current phasor obtained by transformation at a certain sampling time. At the same time, under the premise that the data receiving channel delays on both sides are equal, the channel delay is calculated. The sampling deviation 8 on both sides is obtained by calculating the channel delay. The protection multiplies the received current phasor on the opposite side by the rotation factor to obtain the corrected synchronous sampling data.

[0015] Preferably, in step S3, the protection devices on both sides of the line are synchronously sampled using a sampling time adjustment method. During synchronous sampling, one end of the protection devices on both sides is designated as the master device, and the other end as the slave device. The master device performs free sampling and sends information frames to the slave device. Upon receiving the information, the slave device returns the command and delay time to the master device. The master device calculates the channel delay duration based on the returned data and transmits the data to the slave device. The slave device adjusts its sampling time according to the obtained delay duration data. The sampling time adjustment method transmits a sampling value once per interval. Before the protection function is activated, a synchronization process is required. This synchronization process uses synchronous communication, transmitting a sampling value once per sampling interval using a compact communication frame. The sampling values ​​are then synchronized on the other side using interpolation. After synchronization, professionals conduct real-time observation of the protection devices on both sides. The observation results are processed. If the observation results show that the crystal oscillator frequencies of the protection devices on both sides are the same, no processing is performed. If the observation results show that the crystal oscillator frequencies of the protection devices on both sides are the same, the synchronization process needs to be restarted.

[0016] Preferably, in step S4, a clock correction method is used to perform signal correction again. During correction, one end of the two protections is the reference end and the other end is the synchronization end. The synchronization end sends an information frame. After receiving it, the reference end returns the command and delay time to the synchronization end. The synchronization end calculates the relative error Ar between the two clocks. Following this step, the synchronization end corrects the clocks according to a certain ratio until At is zero, and the two clocks enter a synchronized running state.

[0017] Preferably, in step S5, GPS is used to detect signals at both ends after signal synchronization, and the detection results are used for judgment and processing. If the detection result shows that the information data after signal synchronization has obtained a synchronization signal, it is judged that the signal synchronization is successful. If the detection result shows that the information data after signal synchronization has not obtained a synchronization signal, it is judged that the signal synchronization has failed. If the signal synchronization is judged to be successful, no processing is performed. If the signal synchronization is judged to be successful, no processing is performed, and information timing correction is performed through GPS. After the GPS correction is completed, signal detection is performed again until the detection result shows that the information data after signal synchronization has obtained a synchronization signal.

[0018] Preferably, in step S6, the differential protection signal synchronization method of the distribution network system is tested, and the test results are compared with the existing differential protection signal synchronization method of the distribution network system to calculate the success rate and timeliness of the signal synchronization of the differential protection signal synchronization method of the distribution network system.

[0019] Compared with the prior art, the beneficial effects of the present invention are:

[0020] 1. By employing multiple signal synchronization methods for signal correction, the success rate of signal synchronization has been improved.

[0021] 2. By performing signal detection after successful signal synchronization, the timeliness of signal synchronization is enhanced, avoiding information asynchrony caused by signal synchronization delays.

[0022] The purpose of this invention is to improve the success rate of signal synchronization by using multiple signal synchronization methods for signal correction. At the same time, by performing signal detection after successful signal synchronization, the invention avoids information asynchrony caused by signal synchronization timeliness and enhances the timeliness of signal synchronization. Attached Figure Description

[0023] Figure 1 This is a flowchart of a method for synchronizing differential protection signals in a distribution network system, as proposed in this invention. Detailed Implementation

[0024] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0025] Example 1

[0026] Reference Figure 1 A method for synchronizing differential protection signals in a distribution network system includes the following steps:

[0027] S1: Device preparation: Establish a distribution network system, wherein the system includes a 5G network, optical fiber and GPS. 5G base stations are manually established at equal intervals and intermittently. 5G channels are established through the base stations and signals are transmitted through the 5G channels.

[0028] S2: Preliminary correction: The sampling data correction method is used for preliminary signal correction. When the sampling data correction method is used, the two protections are not distinguished as master and slave. Each protection is controlled by its own crystal oscillator and samples independently at the same sampling frequency. Each frame of data sent contains time stamp information and current sampling data information. The current sampling data is the current phasor obtained by transformation at a certain sampling time. At the same time, under the assumption that the data receiving channel delays on both sides are equal, the channel delay is calculated. The sampling deviation between the two sides is obtained by calculating the channel delay. The protection multiplies the received current phasor on the opposite side by the rotation factor to obtain the corrected synchronous sampling data.

[0029] S3: Synchronous Sampling: Synchronous sampling is performed on the protection devices on both sides of the line using a sampling time adjustment method. During synchronous sampling, one end of the protection devices is designated as the master, and the other end as the slave. The master device performs free sampling and sends information frames to the slave device. Upon receiving the data, the slave device returns the command and delay time to the master device. The master device calculates the channel delay duration based on the returned data and transmits the data to the slave device. The slave device adjusts its sampling time according to the obtained delay duration data. The sampling time adjustment method transmits the sampling value once per interval. Before the protection function is activated, a synchronization process is required. This synchronization process uses synchronous communication, transmitting the sampling value once per sampling interval through a compact communication frame. The sampling values ​​are then synchronized on the other side using interpolation. After synchronization, professionals conduct real-time observation of the protection devices on both sides. The observation results are processed. If the observation results show that the crystal oscillator frequencies of the protection devices on both sides are the same, no processing is performed. If the observation results show that the crystal oscillator frequencies of the protection devices on both sides are the same, the synchronization process needs to be restarted.

[0030] S4: Recalibration: The clock calibration method is used to calibrate the signal again. During calibration, one end of the two protections is the reference end and the other end is the synchronization end. The synchronization end sends an information frame. After receiving it, the reference end returns the command and delay time to the synchronization end. The synchronization end calculates the relative error Ar of the clocks on both sides. Following this step, the synchronization end calibrates the clocks according to a certain ratio until At is zero, and the clocks on both sides enter the synchronous operation state.

[0031] S5: Signal Detection: GPS is used to detect the signal at both ends after signal synchronization, and the detection results are used for judgment and processing. If the detection result shows that the information data after signal synchronization has obtained a synchronization signal, it is judged as signal synchronization successful. If the detection result shows that the information data after signal synchronization has not obtained a synchronization signal, it is judged as signal synchronization failure. If the signal synchronization is judged as successful, no processing is required. If the signal synchronization is judged as successful, information timing correction is performed through GPS. After the GPS correction is completed, signal detection is performed again until the detection result shows that the information data after signal synchronization has obtained a synchronization signal.

[0032] S6: Test Comparison: Test the differential protection signal synchronization method of the distribution network system, and compare the test results with the existing differential protection signal synchronization method of the distribution network system to calculate the success rate and timeliness of the signal synchronization of the differential protection signal synchronization method of the distribution network system.

[0033] Example 2

[0034] Reference Figure 1 A method for synchronizing differential protection signals in a distribution network system includes the following steps:

[0035] S1: Device preparation: Establish a distribution network system, wherein the system includes a 5G network, optical fiber and GPS. 5G base stations are manually established at equal intervals and intermittently. 5G channels are established through the base stations and signals are transmitted through the 5G channels.

[0036] S2: Synchronous Sampling: Synchronous sampling is performed on the protection devices on both sides of the line using a sampling time adjustment method. During synchronous sampling, one end of the protection devices is designated as the master, and the other end as the slave. The master device performs free sampling and sends information frames to the slave device. Upon receiving the data, the slave device returns the command and delay time to the master device. The master device calculates the channel delay duration based on the returned data and transmits the data to the slave device. The slave device adjusts its sampling time according to the obtained delay duration data. The sampling time adjustment method transmits the sampling value once per interval. Before the protection function is activated, a synchronization process is required. This synchronization process uses synchronous communication, transmitting the sampling value once per sampling interval through a compact communication frame. The sampling values ​​are then synchronized on the other side using interpolation. After synchronization, professionals conduct real-time observation of the protection devices on both sides. The observation results are processed. If the observation results show that the crystal oscillator frequencies of the protection devices on both sides are the same, no processing is performed. If the observation results show that the crystal oscillator frequencies of the protection devices on both sides are the same, the synchronization process needs to be restarted.

[0037] S3: Recalibration: The clock calibration method is used to calibrate the signal again. During calibration, one end of the two protections is the reference end and the other end is the synchronization end. The synchronization end sends an information frame. After receiving it, the reference end returns the command and delay time to the synchronization end. The synchronization end calculates the relative error Ar of the clocks on both sides. Following this step, the synchronization end calibrates the clocks according to a certain ratio until At is zero, and the clocks on both sides enter the synchronous operation state.

[0038] S4: Signal Detection: GPS is used to detect the signals at both ends after signal synchronization, and the detection results are used for judgment and processing. If the detection result shows that the information data after signal synchronization has obtained a synchronization signal, it is judged as signal synchronization successful. If the detection result shows that the information data after signal synchronization has not obtained a synchronization signal, it is judged as signal synchronization failure. If the signal synchronization is judged as successful, no processing is required. If the signal synchronization is judged as successful, information timing correction is performed through GPS. After the GPS correction is completed, signal detection is performed again until the detection result shows that the information data after signal synchronization has obtained a synchronization signal.

[0039] S5: Test Comparison: Test the differential protection signal synchronization method of the distribution network system, and compare the test results with the existing differential protection signal synchronization method of the distribution network system to calculate the success rate and timeliness of the signal synchronization of the differential protection signal synchronization method of the distribution network system.

[0040] Example 3

[0041] Reference Figure 1 A method for synchronizing differential protection signals in a distribution network system includes the following steps:

[0042] S1: Device preparation: Establish a distribution network system, wherein the system includes a 5G network, optical fiber and GPS. 5G base stations are manually established at equal intervals and intermittently. 5G channels are established through the base stations and signals are transmitted through the 5G channels.

[0043] S2: Preliminary correction: The sampling data correction method is used for preliminary signal correction. When the sampling data correction method is used, the two protections are not distinguished as master and slave. Each protection is controlled by its own crystal oscillator and samples independently at the same sampling frequency. Each frame of data sent contains time stamp information and current sampling data information. The current sampling data is the current phasor obtained by transformation at a certain sampling time. At the same time, under the assumption that the data receiving channel delays on both sides are equal, the channel delay is calculated. The sampling deviation between the two sides is obtained by calculating the channel delay. The protection multiplies the received current phasor on the opposite side by the rotation factor to obtain the corrected synchronous sampling data.

[0044] S3: Synchronous Sampling: Synchronous sampling is performed on the protection devices on both sides of the line using the sampling time adjustment method. During synchronous sampling, one end of the protection devices on both sides is designated as the master and the other end as the slave. The master device performs free sampling and sends information frames to the slave device. After receiving the data, the slave device returns the command and delay time to the master device. The master device calculates the channel delay time based on the returned data and transmits the data to the slave device. The slave device adjusts its sampling time based on the obtained delay time data. The sampling time adjustment method transmits the sampling value once at intervals. Before the protection function is put into operation, a synchronization process must be performed using the sampling time adjustment method.

[0045] S4: Recalibration: The clock calibration method is used to calibrate the signal again. During calibration, one end of the two protections is the reference end and the other end is the synchronization end. The synchronization end sends an information frame. After receiving it, the reference end returns the command and delay time to the synchronization end. The synchronization end calculates the relative error Ar of the clocks on both sides. Following this step, the synchronization end calibrates the clocks according to a certain ratio until At is zero, and the clocks on both sides enter the synchronous operation state.

[0046] S5: Signal Detection: GPS is used to detect the signal at both ends after signal synchronization, and the detection results are used for judgment and processing. If the detection result shows that the information data after signal synchronization has obtained a synchronization signal, it is judged as signal synchronization successful. If the detection result shows that the information data after signal synchronization has not obtained a synchronization signal, it is judged as signal synchronization failure. If the signal synchronization is judged as successful, no processing is required. If the signal synchronization is judged as successful, information timing correction is performed through GPS. After the GPS correction is completed, signal detection is performed again until the detection result shows that the information data after signal synchronization has obtained a synchronization signal.

[0047] S6: Test Comparison: Test the differential protection signal synchronization method of the distribution network system, and compare the test results with the existing differential protection signal synchronization method of the distribution network system to calculate the success rate and timeliness of the signal synchronization of the differential protection signal synchronization method of the distribution network system.

[0048] Example 4

[0049] Reference Figure 1 A method for synchronizing differential protection signals in a distribution network system includes the following steps:

[0050] S1: Device preparation: Establish a distribution network system, wherein the system includes a 5G network, optical fiber and GPS. 5G base stations are manually established at equal intervals and intermittently. 5G channels are established through the base stations and signals are transmitted through the 5G channels.

[0051] S2: Preliminary correction: The sampling data correction method is used for preliminary signal correction. When the sampling data correction method is used, the two protections are not distinguished as master and slave. Each protection is controlled by its own crystal oscillator and samples independently at the same sampling frequency. Each frame of data sent contains time stamp information and current sampling data information. The current sampling data is the current phasor obtained by transformation at a certain sampling time. At the same time, under the assumption that the data receiving channel delays on both sides are equal, the channel delay is calculated. The sampling deviation between the two sides is obtained by calculating the channel delay. The protection multiplies the received current phasor on the opposite side by the rotation factor to obtain the corrected synchronous sampling data.

[0052] S3: Synchronous Sampling: Synchronous sampling is performed on the protection devices on both sides of the line using a sampling time adjustment method. During synchronous sampling, one end of the protection devices is designated as the master, and the other end as the slave. The master device performs free sampling and sends information frames to the slave device. Upon receiving the data, the slave device returns the command and delay time to the master device. The master device calculates the channel delay duration based on the returned data and transmits the data to the slave device. The slave device adjusts its sampling time according to the obtained delay duration data. The sampling time adjustment method transmits the sampling value once per interval. Before the protection function is activated, a synchronization process is required. This synchronization process uses synchronous communication, transmitting the sampling value once per sampling interval through a compact communication frame. The sampling values ​​are then synchronized on the other side using interpolation. After synchronization, professionals conduct real-time observation of the protection devices on both sides. The observation results are processed. If the observation results show that the crystal oscillator frequencies of the protection devices on both sides are the same, no processing is performed. If the observation results show that the crystal oscillator frequencies of the protection devices on both sides are the same, the synchronization process needs to be restarted.

[0053] S4: Recalibration: The clock calibration method is used to calibrate the signal again. During calibration, one end of the two protections is the reference end and the other end is the synchronization end. The synchronization end sends an information frame, and the reference end returns the command and delay time to the synchronization end after receiving it.

[0054] S5: Signal Detection: GPS is used to detect the signal at both ends after signal synchronization, and the detection results are used for judgment and processing. If the detection result shows that the information data after signal synchronization has obtained a synchronization signal, it is judged as signal synchronization successful. If the detection result shows that the information data after signal synchronization has not obtained a synchronization signal, it is judged as signal synchronization failure. If the signal synchronization is judged as successful, no processing is required. If the signal synchronization is judged as successful, information timing correction is performed through GPS. After the GPS correction is completed, signal detection is performed again until the detection result shows that the information data after signal synchronization has obtained a synchronization signal.

[0055] S6: Test Comparison: Test the differential protection signal synchronization method of the distribution network system, and compare the test results with the existing differential protection signal synchronization method of the distribution network system to calculate the success rate and timeliness of the signal synchronization of the differential protection signal synchronization method of the distribution network system.

[0056] Example 5

[0057] Reference Figure 1 A method for synchronizing differential protection signals in a distribution network system includes the following steps:

[0058] S1: Device preparation: Establish a distribution network system, wherein the system includes a 5G network, optical fiber and GPS. 5G base stations are manually established at equal intervals and intermittently. 5G channels are established through the base stations and signals are transmitted through the 5G channels.

[0059] S2: Preliminary correction: The sampling data correction method is used for preliminary signal correction. When the sampling data correction method is used, the two protections are not distinguished as master and slave. Each protection is controlled by its own crystal oscillator and samples independently at the same sampling frequency. Each frame of data sent contains time stamp information and current sampling data information. The current sampling data is the current phasor obtained by transformation at a certain sampling time. At the same time, under the assumption that the data receiving channel delays on both sides are equal, the channel delay is calculated. The sampling deviation between the two sides is obtained by calculating the channel delay. The protection multiplies the received current phasor on the opposite side by the rotation factor to obtain the corrected synchronous sampling data.

[0060] S3: Synchronous Sampling: Synchronous sampling is performed on the protection devices on both sides of the line using a sampling time adjustment method. During synchronous sampling, one end of the protection devices is designated as the master, and the other end as the slave. The master device performs free sampling and sends information frames to the slave device. Upon receiving the data, the slave device returns the command and delay time to the master device. The master device calculates the channel delay duration based on the returned data and transmits the data to the slave device. The slave device adjusts its sampling time according to the obtained delay duration data. The sampling time adjustment method transmits the sampling value once per interval. Before the protection function is activated, a synchronization process is required. This synchronization process uses synchronous communication, transmitting the sampling value once per sampling interval through a compact communication frame. The sampling values ​​are then synchronized on the other side using interpolation. After synchronization, professionals conduct real-time observation of the protection devices on both sides. The observation results are processed. If the observation results show that the crystal oscillator frequencies of the protection devices on both sides are the same, no processing is performed. If the observation results show that the crystal oscillator frequencies of the protection devices on both sides are the same, the synchronization process needs to be restarted.

[0061] S4: Recalibration: The clock calibration method is used to calibrate the signal again. During calibration, one end of the two protections is the reference end and the other end is the synchronization end. The synchronization end sends an information frame. After receiving it, the reference end returns the command and delay time to the synchronization end. The synchronization end calculates the relative error Ar of the clocks on both sides. Following this step, the synchronization end calibrates the clocks according to a certain ratio until At is zero, and the clocks on both sides enter the synchronous operation state.

[0062] S5: Signal Detection: GPS is used to detect the signals at both ends after signal synchronization, and the detection results are used for judgment and processing. If the detection result shows that the information data after signal synchronization has obtained a synchronization signal, it is judged as signal synchronization successful. If the detection result shows that the information data after signal synchronization has not obtained a synchronization signal, it is judged as signal synchronization failure. If the signal synchronization is judged as successful, no processing is required. If the signal synchronization is judged as successful, information timing correction is performed via GPS. After the GPS correction is completed, signal detection is performed again until the detection result shows that the information data after signal synchronization has obtained a synchronization signal.

[0063] Experiments were conducted on one of the differential protection signal synchronization methods for a distribution network system in Examples 1, 2, 3, 4, and 5, and the results are as follows:

[0064]

[0065] The signal synchronization methods for differential protection of distribution network systems developed in Examples 1, 2, 3, 4, and 5 have significantly improved the signal synchronization success rate compared with existing methods, and Example 1 is the best example.

[0066] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A method for synchronizing differential protection signals in a distribution network system, characterized in that, Includes the following steps: S1: Equipment preparation: Prepare the equipment required for signal synchronization; S2: Preliminary correction: Preliminary signal correction is performed using the sampled data correction method; S3: Synchronous sampling: The protection devices on both sides of the line are sampled synchronously by adjusting the sampling time. S4: Recalibrate: Perform signal recalibration using the clock calibration method; S5: Signal Detection: GPS is used to detect the signals at both ends after signal synchronization, and the detection results are used for judgment and processing; S6: Test and Comparison: Test the differential protection signal synchronization method of the distribution network system and compare it with existing methods; In S1, a distribution network system is established, which includes a 5G network, optical fiber and GPS. 5G base stations are manually established at equal intervals and intermittently. 5G channels are established through the base stations and signals are transmitted through the 5G channels. In S2, the sampling data correction method performs preliminary signal correction. When the sampling data correction method is used, the two protections do not distinguish between master and slave. Each protection is controlled by its own crystal oscillator and samples independently at the same sampling frequency. Each frame of data sent contains time stamp information and current sampling data information. The current sampling data is the current phasor obtained by transformation at a certain sampling time. At the same time, under the assumption that the data receiving channel delays on both sides are equal, the channel delay is calculated. The sampling deviation between the two sides is obtained by calculating the channel delay. The protection multiplies the received current phasor on the opposite side by the rotation factor to obtain the corrected synchronous sampling data. In S3, the protection devices on both sides of the line are synchronously sampled using the sampling time adjustment method. During synchronous sampling, one end of the protection devices on both sides is designated as the master and the other end as the slave. The master performs free sampling and sends information frames to the slave. After receiving the frame, the slave returns the command and delay time to the master. The master calculates the channel delay duration based on the returned data and transmits the data to the slave. The slave then adjusts its sampling time based on the obtained delay duration data.

2. The method for synchronizing differential protection signals in a distribution network system according to claim 1, characterized in that, The sampling time adjustment method transmits a sampling value once per interval. Before the protection function is put into operation, a synchronization process is required. The synchronization process uses synchronous communication, which transmits a sampling value once per sampling interval through a compact communication frame. The sampling values ​​are then synchronized on the other side using interpolation. After synchronization, professionals monitor the protection devices on both sides in real time. The monitoring results are processed. If the monitoring results show that the crystal oscillator frequencies of the protection devices on both sides are the same, no processing is required. If the monitoring results show that the crystal oscillator frequencies of the protection devices on both sides are the same, the synchronization process needs to be restarted.

3. The method for synchronizing differential protection signals in a distribution network system according to claim 1, characterized in that, In step S4, a clock correction method is used to perform signal correction again. During the correction, one end of the two protections is the reference end and the other end is the synchronization end. The synchronization end sends an information frame. After receiving it, the reference end returns the command and delay time to the synchronization end. The synchronization end calculates the relative error Ar of the clocks on both sides. Following this step, the synchronization end corrects the clocks according to a certain ratio until At is zero, and the clocks on both sides enter the synchronous operation state.

4. The method for synchronizing differential protection signals in a distribution network system according to claim 1, characterized in that, In step S5, GPS is used to detect signals at both ends after signal synchronization, and the detection results are used for judgment and processing. If the detection result shows that the information data after signal synchronization has obtained a synchronization signal, it is judged that the signal synchronization is successful. If the detection result shows that the information data after signal synchronization has not obtained a synchronization signal, it is judged that the signal synchronization has failed. If the signal synchronization is judged to be successful, no processing is performed. If the signal synchronization is judged to be successful, no processing is performed, and information timing correction is performed through GPS. After the GPS correction is completed, signal detection is performed again until the detection result shows that the information data after signal synchronization has obtained a synchronization signal.

5. The method for synchronizing differential protection signals in a distribution network system according to claim 1, characterized in that, In step S6, the differential protection signal synchronization method of the distribution network system is tested, and the test results are compared with the existing differential protection signal synchronization method of the distribution network system to calculate the success rate and timeliness of the signal synchronization of the differential protection signal synchronization method of the distribution network system.

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