A hybrid networking method and system for power distribution terminal devices

Abstract

The present invention discloses a hybrid networking method for a power distribution terminal device, comprising: setting an Ethernet transmission scheduling module, an Ethernet receiving and synchronization time stamp processing module, and a sampling data synchronization module for each DTU device participating in the hybrid networking, and configuring the network type used for communication between each DTU device; selecting a synchronization mode and configuring an Ethernet port type according to the communication network type, and setting a communication interface according to the configured Ethernet port type; the local DTU device receives the sampling messages sent by each opposite DTU device; the local DTU device parses the messages sent by each opposite DTU device, obtains the timestamp corresponding to the opposite sampling data and performs time stamp conversion on it, and obtains the corresponding local crystal oscillator timestamp; the local DTU device performs difference resampling on each opposite sampling data received in combination with the timestamp corresponding to the local sampling data, and obtains synchronous sampling data. The present invention enables the DTU device supporting differential protection to support multiple networking modes, and improves the networking compatibility of the distribution network differential protection DTU device at the engineering site.

Description

Technical Field

[0001] The present invention relates to the technical field of relay protection, and more specifically, to a hybrid networking method and system for a power distribution terminal device. Background Art

[0002] The Distribution Terminal Unit (DTU) is one of the important devices in the distribution network, which is used to collect and calculate the data of the primary quantity in the power grid. Due to the disadvantages of the traditional overcurrent protection principle of DTU, such as complex setting, large power outage range, long delay, and easy over-tripping, the current DTU device adds the differential protection principle in the design to more accurately locate and quickly isolate the fault point.

[0003] Generally, devices that support differential protection will set up a dedicated optical fiber network to connect the devices on both sides point-to-point. However, in the actual application scenarios of distribution networks, some sites are not equipped with dedicated differential protection optical fiber channels. Therefore, when designing distribution network DTU equipment, it is necessary to consider compatibility with various communication networks such as optical fiber, cable, 4G, 5G, etc.

[0004] The existing DTU devices that support differential protection in the industry mainly include the following solutions: one is based on the fiber optic ping-pong synchronization solution, which uses fiber optic and other wired networks for global networking; the other is based on external time synchronization, which uses an external time source synchronization solution globally, and uses 5G and other wireless networks for global networking. Since the ping-pong synchronization solution can only be used in a rigid network environment with a fixed delay and cannot be used in a wireless network, and the external time synchronization must be configured with a time source for the DTU device, currently at the engineering site, the differential networking of the DTU can only select one networking mode globally, and the networking compatibility at the engineering site is poor. Summary of the invention

[0005] In order to solve the deficiencies in the prior art, the object of the present invention is to provide a hybrid networking method for distribution terminal devices, which can improve the networking compatibility of distribution network differential protection DTU devices at engineering sites.

[0006] The present invention adopts the following technical solution.

[0007] A hybrid networking method for a power distribution terminal device comprises the following steps:

[0008] Step 1: Set an Ethernet transmission scheduling module, an Ethernet reception and synchronization time stamp processing module, and a sampling data synchronization module for each DTU device participating in the hybrid network. The Ethernet transmission scheduling module of the DTU device on this side configures the network type used for communication with each DTU device on the opposite side;

[0009] Step 2: The Ethernet transmission scheduling module of the DTU device on this side selects the synchronization mode and configures the Ethernet port type according to the network type for communicating with each opposite-side DTU device, and sets the communication interface for each opposite-side DTU device according to the configured Ethernet port type;

[0010] Step 3: The DTU device on this side receives the message sent by the Ethernet transmission scheduling module of each opposite-side DTU device according to the type of Ethernet port configured between it and each opposite-side DTU device. The message includes a sampling message, and a ping-pong message required for optical fiber differential or an IP protocol message used in a wireless network. The sampling message also includes sampling data and a timestamp corresponding to the sampling data.

[0011] Step 4: The Ethernet receiving and synchronization time stamp processing module of the DTU device on this side receives and parses the messages sent by each DTU device on the opposite side, obtains the timestamp corresponding to the sampling data on the opposite side, and performs time stamp conversion on it to obtain the corresponding crystal oscillator timestamp on this side;

[0012] Step 5: The sampling data synchronization module of the DTU device on this side performs difference resampling on the received sampling data on each opposite side in combination with the timestamp corresponding to the sampling data on this side to obtain synchronous sampling data for the differential protection function.

[0013] Preferably, in step 1, the network types used by the Ethernet transmission scheduling module of the DTU device on the local side to communicate with the DTU device on the opposite side include rigid networks and non-rigid networks;

[0014] Among them, a rigid network is a network with fixed network route, fixed communication delay, and equal round-trip communication delay; a non-rigid network is a network that does not satisfy the requirements of fixed route, fixed communication delay, and equal round-trip communication delay.

[0015] Preferably, in step 2, selecting a synchronization mode according to the network type and configuring the Ethernet port type further comprises:

[0016] For the opposite DTU device that uses a rigid network for communication, the synchronization mode is set to use the ping-pong method for synchronization, and the Ethernet port used is configured as the first type;

[0017] For the opposite DTU device that uses a non-rigid network for communication, the synchronization mode is set to achieve synchronization based on an external timing source, and the Ethernet port it uses is configured as the second type.

[0018] Preferably, in step 2, setting a communication interface for each opposite-side DTU device according to the configured Ethernet port type further includes:

[0019] For the opposite DTU device using the first type of Ethernet port, the communication interface is a dedicated communication Ethernet interface for each opposite DTU device;

[0020] For the opposite DTU device using the second type of Ethernet port, its communication interface is configured to support multiple opposite DTU devices to share one Ethernet interface for networking and communication, which can be used to connect a wireless CPE device or a wireless module.

[0021] Preferably, in step 3, when the Ethernet sending scheduling module of the opposite DTU device sends the sampled data, the sampling timestamp of the sampling time of the data is also sent:

[0022] For an Ethernet port configured as the first type, the sampling time is timestamped using the internal crystal oscillator clock on the same time axis as the time when the ping-pong message is sent;

[0023] For a network port configured as the second type, an external clock source is used to timestamp the sampling moment.

[0024] Preferably, in step 3, sending the message further includes:

[0025] The Ethernet transmission scheduling module uses a time-sharing method to control message transmission, dividing each second into 8000 equally spaced time slices, each time slice is 125us, and sending sampled data and messages through time slices.

[0026] Preferably, in step 4, when the local DTU device is connected to multiple opposite DTU devices, data is sent to each opposite DTU device and data sent by each opposite DTU device is received according to the communication network type between the local DTU device and each opposite DTU device.

[0027] Preferably, the step 4 further comprises:

[0028] For the opposite DTU device using the first type of Ethernet port, after receiving the opposite sampling data and its corresponding timestamp, the Ethernet receiving and synchronization time stamp processing module converts the opposite sampling timestamp into a local crystal oscillator timestamp based on the ping-pong method;

[0029] For the opposite DTU device using the second type of Ethernet port, after the Ethernet receiving and synchronization time stamp processing module receives the opposite sampling data and its corresponding timestamp, it converts the opposite sampling timestamp into a local crystal oscillator timestamp based on an external timing source.

[0030] Preferably, the step 5 further comprises:

[0031] The DTU device on this side can generate sampling data on this side, and obtain the timestamp corresponding to the sampling data on this side through the crystal oscillator clock of the DTU device on this side. The sampling data synchronization module of the DTU device on this side combines the timestamp corresponding to the sampling data on this side and the crystal oscillator timestamp on this side corresponding to the timestamp of the sampling data on the opposite side obtained in step 4, and performs difference resampling on the received sampling data on each opposite side to obtain synchronized sampling data. The obtained synchronized sampling data is used for the differential protection function.

[0032] The present invention also provides a hybrid networking system of a power distribution terminal device, including: an Ethernet transmission scheduling module, an Ethernet reception and synchronization time stamp processing module, and a sampling data synchronization module, and the above modules are deployed on each DTU device;

[0033] The Ethernet transmission scheduling module can configure the network type used for communication with each opposite-side DTU device, and is used to send sampling data, ping-pong messages required for optical fiber differential and IP protocol messages used in wireless networks to the opposite-side DTU device;

[0034] The Ethernet receiving and synchronization time stamp processing module is used to receive and process various messages sent by the opposite DTU device, and perform time stamp conversion to obtain the local crystal oscillator timestamp;

[0035] The sampling data synchronization module can perform difference resampling on the sampling data pushed by each opposite-side DTU based on the timestamp of the local sampling data and the crystal oscillator timestamp on the local side corresponding to the timestamp of the opposite-side sampling data obtained after time-scale conversion to obtain synchronized sampling data.

[0036] The beneficial effect of the present invention is that, compared with the prior art, a method for supporting hybrid networking of a distribution network DTU is provided, which solves the adaptation problem of different communication networks such as optical fiber, cable, 4G, 5G, etc. after the distribution network DTU device adds a differential protection function, so that it supports multiple networking modes, greatly reduces the construction and use costs of using differential protection in the distribution network, and improves the networking compatibility of the distribution network differential protection DTU device at the engineering site. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a schematic diagram of the overall process of the hybrid networking method of the power distribution terminal device in the present invention;

[0038] Figure 2 It is a schematic diagram of the time-sharing occupancy mode control message sending that can be used in the present invention;

[0039] Figure 3 It is a schematic diagram of a hybrid network of multiple DTU devices using optical fiber and 5G wireless network in the present invention;

[0040] Figure 4It is a schematic diagram of the overall structure of the hybrid networking system of the power distribution terminal device in the present invention. DETAILED DESCRIPTION

[0041] The present application is further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present application.

[0042] like Figure 1 As shown, the present invention provides a hybrid networking method for a power distribution terminal device, the method specifically comprising the following steps:

[0043] Step 1: Set an Ethernet transmission scheduling module, an Ethernet reception and synchronization time stamp processing module, and a sampling data synchronization module for each DTU device participating in the hybrid network. The Ethernet transmission scheduling module of the DTU device on this side configures the network type used for communication with each DTU device on the opposite side;

[0044] Specifically, hybrid networking means that when multiple DTU devices are connected, the entire network uses multiple communication methods at the same time when networking, such as Figure 3 As shown, Figure 3 This is a schematic diagram of the network structure that uses both optical fiber and 5G for hybrid networking. Differential protection requires that the sampling data of two adjacent devices be transmitted to each other, and differential protection is achieved by comparing the data on both sides. However, in the distribution network, a device may need to simultaneously realize the differential protection function with several surrounding devices. In the end, multiple protection devices in the entire area will form an interconnected network.

[0045] In a hybrid network, an Ethernet sending scheduling module, an Ethernet receiving and synchronization time stamp processing module and a sampling data synchronization module need to be set for each DTU device. The DTU device in the present invention is a distribution terminal device that supports differential protection, and each DTU device can communicate with other DTU devices. The two DTU devices that need to communicate with each other send data through their respective Ethernet sending scheduling modules.

[0046] Each DTU device can be used as a local DTU device, and the other DTU devices communicating with it are opposite DTU devices, that is, each DTU device can be used as a local DTU device and as an opposite DTU device of other DTU devices.

[0047] Specifically, according to the connection mode of communication between the local DTU device and the opposite DTU device, the network type used by the Ethernet transmission scheduling module of the local DTU device to communicate with the opposite DTU device is divided into a rigid network and a non-rigid network;

[0048] Among them, a rigid network is a network with fixed network routing, fixed communication delay, and equal round-trip communication delay, such as directly connecting two DTU devices with optical fiber;

[0049] A non-rigid network is a network that does not meet the requirements of fixed routing, fixed communication delay, and equal round-trip communication delay. When the optical fiber or network cable connecting two DTU devices passes through devices such as switches and routers, the intermediate nodes may cause uncertain delays and different routes, resulting in each frame of the message not necessarily being fixed. Therefore, this is a non-rigid network. For DTU devices connected via a wireless network, the network environment of the wireless network is more complex, so the wireless network is a non-rigid network.

[0050] Step 2: The Ethernet transmission scheduling module of the DTU device on this side selects the synchronization mode and configures the Ethernet port type according to the network type for communicating with each opposite-side DTU device, and sets the communication interface for each opposite-side DTU device according to the configured Ethernet port type;

[0051] Specifically, for the opposite DTU device that uses a rigid network for communication, the synchronization mode is set to use the ping-pong method for synchronization, and the Ethernet port used by it is configured as the first type;

[0052] For the opposite DTU device that uses a non-rigid network for communication, the synchronization mode is set to achieve synchronization based on an external timing source, and the Ethernet port it uses is configured as the second type.

[0053] Further, for the opposite-side DTU device using the first type of Ethernet port, the communication interface is a dedicated communication Ethernet interface for each opposite-side DTU device;

[0054] For the opposite DTU device using the second type of Ethernet port, its communication interface is configured to support multiple opposite DTU devices to share one Ethernet interface for networking and communication, which can be used to connect a wireless CPE device or a wireless module.

[0055] Step 3: The DTU device on this side receives the message sent by the Ethernet transmission scheduling module of each opposite-side DTU device according to the type of Ethernet port configured between it and each opposite-side DTU device. The message includes a sampling message, and a ping-pong message required for optical fiber differential or an IP protocol message used in a wireless network. The sampling message also includes sampling data and a timestamp corresponding to the sampling data.

[0056] Specifically, the opposite side sampling data generated by the opposite side DTU device and the timestamp corresponding to the sampling data are used to form a sampling message that is sent to the local DTU device. According to the network type used for communication between the local DTU device and the opposite side DTU device, the ping-pong message required for the optical fiber differential or the IP protocol message used in the wireless network is selected and sent to the local DTU device together with the sampling message.

[0057] Among them, when sending the sampled data, the Ethernet sending scheduling module of the opposite DTU device also sends the sampling timestamp of the sampling time of the data, specifically:

[0058] For an Ethernet port configured as the first type, the sampling time is timestamped using the internal crystal oscillator clock on the same time axis as the time when the ping-pong message is sent;

[0059] For a network port configured as the second type, an external clock source is used to timestamp the sampling moment.

[0060] Furthermore, according to the Ethernet port type and synchronization mode configured between the DTU devices, it is also necessary to send ping-pong messages required for optical fiber differential or IP protocol messages used in wireless networks.

[0061] Specifically, the Ethernet sending scheduling module uses a time-sharing method to control message sending, dividing each second into 8000 equally spaced time slices, each time slice is 125us. For an Ethernet with a bandwidth of 100M, about 1562 bytes of data can be transmitted. When sampling at a sampling rate of 2000, each sampling cycle corresponds to 4 time slices, which are labeled time slice 1, time slice 2, time slice 3 and time slice 4 respectively.

[0062] like Figure 2 As shown, for the Ethernet port configured as the first type, the Ethernet transmission scheduling module fixedly uses time slice 1 to send sampled data, uses time slice 3 to send ping-pong messages, and limits sending only one frame of messages at a time, and updates the sending time in the ping-pong message before sending, to ensure that the ping-pong message sending time is accurate and not affected by the sampling message;

[0063] For the Ethernet port configured as the second type, the Ethernet sending scheduling module uses time slice 1 to continuously send sampling data to each opposite DTU device. Since the opposite DTU device using the second type of Ethernet port supports multiple opposite DTU devices to share one Ethernet interface to communicate with the Ethernet sending scheduling module, the Ethernet sending scheduling module can continuously send sampling data to multiple opposite DTU devices, and the total sending time can exceed the time slice 1. Therefore, time slice 2 and time slice 3 are retained, and time slice 4 is used to send IP protocol packets, and it is limited to only one frame of IP protocol packets to be sent each time in time slice 4 to ensure the bandwidth of the sampling data.

[0064] Furthermore, since the DTU device on this side can be connected to multiple DTU devices on the opposite side, when connected to multiple DTU devices on the opposite side, data is sent to each DTU device on the opposite side and data sent by each DTU device on the opposite side is received according to the communication network type between the DTU device on this side and each DTU device on the opposite side.

[0065] Step 4: The Ethernet receiving and synchronization time stamp processing module of the DTU device on this side receives and parses the messages sent by each DTU device on the opposite side, obtains the timestamp corresponding to the sampling data on the opposite side, and performs time stamp conversion on it to obtain the corresponding crystal oscillator timestamp on this side;

[0066] Specifically, after parsing the sampling message, the opposite side sampling data sent by the opposite side DTU device and the timestamp corresponding to the sampling data are obtained;

[0067] The time stamp conversion of the timestamp corresponding to the sampling data on the opposite side also includes:

[0068] For the opposite DTU device using the first type of Ethernet port, after the Ethernet receiving and synchronization time stamp processing module receives the timestamp corresponding to the opposite sampling data, it converts the sampling timestamp of the opposite side into the crystal oscillator timestamp of the local side based on the ping-pong method;

[0069] For the opposite DTU device using the second type of Ethernet port, after the Ethernet receiving and synchronization time stamp processing module receives the timestamp corresponding to the opposite sampling data, it converts the opposite sampling timestamp into the crystal oscillator timestamp of this side based on the external timing source.

[0070] Through time scale conversion, the timestamp corresponding to the sampling data on each opposite side in the crystal oscillator clock of the DTU device on this side is obtained.

[0071] Step 5: The sampling data synchronization module of the DTU device on the local side performs difference resampling on the received sampling data on each opposite side in combination with the timestamp corresponding to the sampling data on the local side to obtain synchronized sampling data.

[0072] Specifically, the local DTU device can generate local sampling data, and the timestamp corresponding to the local sampling data is obtained by the crystal oscillator clock of the local DTU device itself combined with the generation time of the sampling data;

[0073] The sampling data synchronization module of the DTU device on this side combines the timestamp corresponding to the sampling data on this side and the crystal oscillator timestamp on this side corresponding to the timestamp of the sampling data on the opposite side obtained in step 4, and performs difference resampling on the received sampling data on each opposite side to obtain synchronized sampling data. The obtained synchronized sampling data is used for the differential protection function.

[0074] like Figure 4As shown, the present invention also provides a hybrid networking system for power distribution terminal devices, and the hybrid networking method of the power distribution terminal devices can be implemented through the system. The system specifically includes: an Ethernet transmission scheduling module, an Ethernet receiving and synchronization time stamp processing module, and a sampling data synchronization module. The above modules are deployed on each DTU device;

[0075] The Ethernet transmission scheduling module can configure the network type used for communication with each opposite-side DTU device, and is used to send sampling data, ping-pong messages required for optical fiber differential and IP protocol messages used in wireless networks to the opposite-side DTU device;

[0076] The Ethernet receiving and synchronization time stamp processing module is used to receive and process various messages sent by the opposite DTU device, and perform time stamp conversion to obtain the local crystal oscillator timestamp;

[0077] The sampling data synchronization module can perform difference resampling on the sampling data pushed by each opposite-side DTU based on the timestamp of the local sampling data and the crystal oscillator timestamp on the local side corresponding to the timestamp of the opposite-side sampling data obtained after time-scale conversion to obtain synchronized sampling data.

[0078] Definition of noun:

[0079] DTU: Distribution Terminal Unit, power distribution terminal device;

[0080] IP protocol: Internet Protocol.

[0081] The beneficial effect of the present invention lies in that, compared with the prior art, the present invention can solve the adaptation problem of different communication networks such as optical fiber, cable, 4G, 5G, etc. faced with the addition of differential protection function to the distribution network DTU device. The present invention enables a DTU device to communicate with multiple opposite-side DTU devices by controlling the working mode of the network port that communicates with each opposite-side DTU according to the respective communication network types when the device needs to communicate, thereby realizing a hybrid networking function, improving the networking compatibility of the distribution network differential protection DTU device at the engineering site, and greatly reducing the construction and use costs of using differential protection in the distribution network.

[0082] The applicant of the present invention has made a detailed explanation and description of the implementation examples of the present invention in conjunction with the drawings in the specification. However, those skilled in the art should understand that the above implementation examples are only preferred implementation schemes of the present invention, and the detailed description is only to help readers better understand the spirit of the present invention, but not to limit the scope of protection of the present invention. On the contrary, any improvements or modifications based on the inventive spirit of the present invention should fall within the scope of protection of the present invention.

Claims

1. A hybrid networking method for a power distribution terminal device, characterized in that: The following steps are involved: Step 1: Set an Ethernet transmission scheduling module, an Ethernet reception and synchronization time stamp processing module, and a sampling data synchronization module for each DTU device participating in the hybrid network. The Ethernet transmission scheduling module of the DTU device on this side configures the network type used for communication with each DTU device on the opposite side; Step 2: The Ethernet transmission scheduling module of the DTU device on this side selects the synchronization mode and configures the Ethernet port type according to the network type for communicating with each opposite-side DTU device, and sets the communication interface for each opposite-side DTU device according to the configured Ethernet port type; Step 3: The DTU device on this side receives the message sent by the Ethernet transmission scheduling module of each opposite-side DTU device according to the type of Ethernet port configured between it and each opposite-side DTU device. The message includes a sampling message, and a ping-pong message required for optical fiber differential or an IP protocol message used in a wireless network. The sampling message also includes sampling data and a timestamp corresponding to the sampling data. Step 4: The Ethernet receiving and synchronization time stamp processing module of the DTU device on this side receives and parses the messages sent by each DTU device on the opposite side, obtains the timestamp corresponding to the sampling data on the opposite side, and performs time stamp conversion on it to obtain the corresponding crystal oscillator timestamp on this side; Step 5: The sampling data synchronization module of the DTU device on this side performs difference resampling on the received sampling data on each opposite side in combination with the timestamp corresponding to the sampling data on this side to obtain synchronous sampling data for the differential protection function.

2. The hybrid networking method of the power distribution terminal device according to claim 1, characterized in that: In the step 1, the network type used by the Ethernet transmission scheduling module of the DTU device on the local side to communicate with the DTU device on the opposite side includes a rigid network and a non-rigid network; Among them, a rigid network is a network with fixed network route, fixed communication delay, and equal round-trip communication delay; a non-rigid network is a network that does not satisfy the requirements of fixed route, fixed communication delay, and equal round-trip communication delay.

3. The hybrid networking method of the power distribution terminal device according to claim 1, characterized in that: In step 2, selecting a synchronization mode and configuring an Ethernet port type according to the network type also includes: For the opposite DTU device that uses a rigid network for communication, the synchronization mode is set to use the ping-pong method for synchronization, and the Ethernet port used is configured as the first type; For the opposite DTU device that uses a non-rigid network for communication, the synchronization mode is set to achieve synchronization based on an external timing source, and the Ethernet port it uses is configured as the second type.

4. The hybrid networking method of the power distribution terminal device according to claim 3, characterized in that: In step 2, setting a communication interface for each opposite-side DTU device according to the configured Ethernet port type also includes: For the opposite DTU device using the first type of Ethernet port, the communication interface is a dedicated communication Ethernet interface for each opposite DTU device; For the opposite DTU device using the second type of Ethernet port, its communication interface is configured to support multiple opposite DTU devices to share one Ethernet interface for networking and communication, which can be used to connect a wireless CPE device or a wireless module.

5. The hybrid networking method of the power distribution terminal device according to claim 1, characterized in that: In step 3, when the Ethernet sending scheduling module of the opposite DTU device sends the sampled data, the sampling timestamp of the sampling time of the data is also sent: For an Ethernet port configured as the first type, the sampling time is timestamped using the internal crystal oscillator clock on the same time axis as the time when the ping-pong message is sent; For a network port configured as the second type, an external clock source is used to timestamp the sampling moment.

6. The hybrid networking method of the power distribution terminal device according to claim 1, characterized in that: In step 3, sending the message also includes: The Ethernet transmission scheduling module uses a time-sharing method to control message transmission, dividing each second into 8000 equally spaced time slices, each time slice is 125us, and sending sampled data and messages through time slices.

7. The hybrid networking method of the power distribution terminal device according to claim 6, characterized in that: In step 4, when the local DTU device is connected to multiple opposite DTU devices, data is sent to each opposite DTU device and data sent by each opposite DTU device is received according to the communication network type between the local DTU device and each opposite DTU device.

8. The hybrid networking method of a power distribution terminal device according to claim 1, characterized in that: The step 4 also includes: For the opposite DTU device using the first type of Ethernet port, after receiving the opposite sampling data and its corresponding timestamp, the Ethernet receiving and synchronization time stamp processing module converts the opposite sampling timestamp into a local crystal oscillator timestamp based on the ping-pong method; For the opposite DTU device using the second type of Ethernet port, after the Ethernet receiving and synchronization time stamp processing module receives the opposite sampling data and its corresponding timestamp, it converts the opposite sampling timestamp into a local crystal oscillator timestamp based on an external timing source.

9. The hybrid networking method of a power distribution terminal device according to claim 1, characterized in that: The step 5 also includes: The DTU device on this side can generate sampling data on this side, and obtain the timestamp corresponding to the sampling data on this side through the crystal oscillator clock of the DTU device on this side. The sampling data synchronization module of the DTU device on this side combines the timestamp corresponding to the sampling data on this side and the crystal oscillator timestamp on this side corresponding to the timestamp of the sampling data on the opposite side obtained in step 4, and performs difference resampling on the received sampling data on each opposite side to obtain synchronized sampling data. The obtained synchronized sampling data is used for the differential protection function.

10. A hybrid networking system for power distribution terminal devices using the hybrid networking method for power distribution terminal devices according to any one of claims 1 to 9, characterized in that: include: Ethernet transmission scheduling module, Ethernet reception and synchronization time stamp processing module, sampling data synchronization module, the above modules are deployed on each DTU device; Among them, the Ethernet transmission scheduling module can configure the network type used for communication with each opposite-side DTU device, and is used to send sampling data, ping-pong messages required for optical fiber differential and IP protocol messages used in wireless networks to the opposite-side DTU device; The Ethernet receiving and synchronization time stamp processing module is used to receive and process various messages sent by the opposite DTU device, and perform time stamp conversion to obtain the local crystal oscillator timestamp; The sampling data synchronization module can perform difference resampling on the sampling data pushed by each opposite-side DTU based on the timestamp of the local sampling data and the crystal oscillator timestamp on the local side corresponding to the timestamp of the opposite-side sampling data obtained after time-scale conversion to obtain synchronized sampling data.

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