Message transmission method and multi-terminal differential protection reliability improvement method

Abstract

The invention relates to the technical field of relay protection, in particular to a message transmission method and a multi-terminal differential protection reliability improving method.The message transmission method comprises the steps that multiple sub-channels used for transmitting messages are constructed; the target wireless communication terminal receives the message sent by the target line protection device, and groups the received message according to a preset rule to obtain a message group; wherein the target line protection device is a line protection device in wired connection with the target wireless communication terminal; judging whether the message group is cached for a first preset time length or not; and if yes, the target wireless communication terminal sends the message group to other wireless communication terminals through the multiple sub-channels. According to the invention, a multi-terminal differential protection channel with consistent received and transmitted message delays is constructed, the realization difficulty of multi-terminal differential protection is greatly reduced, and a reliable and convenient communication channel is provided for differential protection of a multi-terminal line.

Description

Technical Field

[0001] The present invention relates to the technical field of relay protection, and in particular to a message transmission method and a method for improving the reliability of multi-terminal differential protection. Background Art

[0002] With the continuous deepening of the construction of new power systems, the structure of power systems is undergoing significant changes, including the flexible access of a large number of distributed power sources to the distribution network in a T-connected manner. This trend makes overhead lines present complex multi-terminal and multi-power characteristics, posing a severe challenge to traditional relay protection technology. Traditional protection methods that mainly rely on overcurrent protection are often difficult to quickly and accurately identify and isolate faults when faced with such complex network structures, thus affecting the stability and reliability of the power system.

[0003] In order to adapt to the multi-terminal scenario of distributed power access, the existing technology adopts multi-terminal line differential protection technology. This technology has become an ideal choice to solve the problem of multi-terminal line protection after distributed power access. However, in practical applications, the existing differential protection system mainly relies on optical fiber as a communication channel, which exposes many limitations in the distribution network environment.

[0004] First, the coverage of optical fiber in distribution networks is generally low, and due to the complexity of distribution network lines and the changing environment, the laying of optical fiber is difficult and costly, which greatly limits the widespread application of optical fiber communication in differential protection. Secondly, for multi-terminal line scenarios, the number of optical fiber interfaces required increases significantly, which not only increases the complexity and cost of the system, but also further increases the difficulty of implementation, causing the promotion of optical fiber communication solutions to encounter bottlenecks.

[0005] In addition, although 5G communication technology has shown great potential in many fields with its high speed and low latency, when applied to multi-terminal line differential protection, the transmission and reception delays of its communication channels are inconsistent, which requires the system to rely on external clocks to achieve data synchronization. However, the introduction of external clocks not only increases the complexity and cost of the system, but may also introduce new fault points and reduce the overall reliability of the system.

[0006] In summary, there is an urgent need for a reliable communication channel that can support multi-terminal line differential protection. This channel must have the characteristics of high coverage, low cost, easy installation and high reliability to meet the urgent needs of new power systems for relay protection technology. Summary of the invention

[0007] The purpose of the present invention is to provide a message transmission method and a method for improving the reliability of multi-terminal differential protection in order to solve at least one of the above technical problems.

[0008] The present invention achieves the above-mentioned purpose through the following technical solutions:

[0009] A message transmission method is applied to a multi-terminal differential protection system having multiple line protection devices, each line protection device is connected to a wireless communication terminal by wire, and the wireless communication terminals are connected to each other by wireless; the message transmission method comprises the following steps:

[0010] Construct multiple sub-channels for transmitting messages;

[0011] The target wireless communication terminal receives the message sent by the target line protection device, and groups the received message according to a preset rule to obtain a message group; wherein the target line protection device is a line protection device connected to the target wireless communication terminal by wire;

[0012] It is determined whether the message group has been cached for a first preset time period; if so, the target wireless communication terminal sends the message group to other wireless communication terminals through the multiple sub-channels.

[0013] Furthermore, constructing multiple sub-channels for transmitting messages includes the following steps:

[0014] Setting a different communication address for each wireless wireless communication terminal;

[0015] Based on the communication address, the target wireless communication terminal establishes a communication sub-channel between the target line protection device and other wireless communication terminals.

[0016] Furthermore, the preset rule is: dividing the received messages into a plurality of message groups based on the message interval, the sampling sequence number and the target address.

[0017] Furthermore, the time difference Δt between the reception time of the nth frame message and the first frame message is calculated n_recv , when Δt n_recv <T int If the sampling sequence number of the current message is consistent with the sampling sequence number of the first frame message, and the target address is different from that of the first frame message, the current frame message and the first frame message are determined to be in the same group;

[0018] Where n is an integer ranging from 2 to (N-1), N is the number of terminals of the multi-terminal differential, T int The sampling interval.

[0019] Further, the current message receiving time is recorded, and it is determined whether the time difference between the current message receiving time and the previous frame message receiving time is greater than the second preset time length; if so, it is determined that the frame is the first frame message of a group of messages;

[0020] The second preset time length T 1 =T 1 =1 / (N-2)*T int ,

[0021] Where N is the number of terminals of the multi-terminal differential, T int The sampling interval.

[0022] Furthermore, the first preset time length T n_bufset for:

[0023]

[0024] Among them, T n_bufset is the first preset duration; T 1 is the second preset duration; Δt n_recv It is the difference in receiving time between the nth frame message and the first frame message in the message group; the value range of n is 1 to (N-1); N is the number of multi-terminal differential terminals.

[0025] Furthermore, each wireless communication terminal uses an internal clock source for time synchronization;

[0026] Each wireless communication terminal outputs a pulse-per-second signal to the line protection device connected thereto for use in differential synchronization error calculation.

[0027] A method for improving the reliability of multi-terminal differential protection, using any of the message transmission methods described above, the method for improving the reliability of multi-terminal differential protection comprises the following steps:

[0028] The local wireless communication terminal receives the message sent by the target communication terminal, and parses the received message to obtain the target sampling time;

[0029] Obtain the sampling time of the line protection device on this side;

[0030] Determine whether the target sampling time and the local sampling time meet the action conditions; if so, execute open differential protection; otherwise, lock differential protection.

[0031] Furthermore, the action condition is:

[0032] The time difference between the target sampling time and the local sampling time is less than a third preset time length.

[0033] A message transmission system, comprising:

[0034] A construction module is used to construct multiple sub-channels for transmitting messages;

[0035] A grouping module, wherein the target wireless communication terminal receives a message sent by a target line protection device, and groups the received message according to a preset rule to obtain a message group; wherein the target line protection device is a line protection device connected to the target wireless communication terminal by wire;

[0036] The judging module judges whether the message group has been cached for a first preset time period; if so, the target wireless communication terminal sends the message group to other wireless communication terminals through the multiple sub-channels.

[0037] The beneficial effects of the present invention are:

[0038] The present invention realizes the mapping of wired channel time division multiplexing to wireless multiple sub-channel parallel transmission by adopting a method of dynamically adjusting the cache start time and duration. When only a single communication interface is used, a multi-terminal differential protection channel with consistent delay in sending and receiving messages is constructed, which greatly reduces the difficulty of implementing multi-terminal differential protection and provides a reliable and convenient communication channel for multi-terminal differential protection. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 It is a structural schematic diagram of a multi-terminal differential protection system having multiple line protection devices;

[0040] Figure 2 A flow chart of a message transmission method according to an embodiment of the present invention;

[0041] Figure 3 A flow chart of a method for improving reliability of multi-terminal differential protection according to an embodiment of the present invention;

[0042] Figure 4 A schematic diagram of the structure of a message transmission system according to an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The content of the present invention will now be discussed with reference to exemplary embodiments. It should be understood that the embodiments discussed are only to enable those skilled in the art to better understand and thus implement the content of the present invention, rather than implying any limitation on the scope of the present invention.

[0044] As used herein, the term “including” and variations thereof are to be interpreted as open-ended terms meaning “including, but not limited to.” The term “based on” is to be interpreted as “based, at least in part, on.” The terms “one embodiment” and “an embodiment” are to be interpreted as “at least one embodiment.”

[0045] Embodiment 1

[0046] Figure 1 It is a structural schematic diagram of a multi-terminal differential protection system having multiple line protection devices; Figure 2 FIG. 1 is a flow chart of a message transmission method according to an embodiment of the present invention. Figure 1-2As shown, according to an embodiment of the present invention, a message transmission method is applied to a multi-terminal differential protection system having multiple line protection devices, each line protection device is connected to a wireless communication terminal by wire, and the wireless communication terminals are connected to each other by wireless; the message transmission method comprises the following steps:

[0047] Step S102: construct multiple sub-channels for transmitting messages;

[0048] Step S104: the target wireless communication terminal receives the message sent by the target line protection device, and groups the received message according to a preset rule to obtain a message group;

[0049] Wherein, the target line protection device is a line protection device connected to the target wireless communication terminal by wire;

[0050] Step S106: Determine whether the message group has been cached for a first preset time period; if so, the target wireless communication terminal sends the message group to other wireless communication terminals through multiple sub-channels.

[0051] In this embodiment, the multi-terminal differential protection system includes multiple line protection devices, each of which is connected to a wireless communication terminal by wire, and each wireless communication terminal is connected to the corresponding line protection device through one or more wired channels; the wireless communication terminal receives data from the line protection device, constructs multiple wireless sub-channels, transmits the message to the wireless communication terminal on the other side, and then sends it to the corresponding line protection device, thereby constructing a multi-terminal differential protection data transmission channel with consistent sending and receiving delays.

[0052] Multiple sub-channels are established. The wireless communication terminal receives the message group division of the line protection device. The wireless communication terminal maps a wired channel into multiple wireless sub-channels according to the target address, and sends the message to the corresponding wireless communication terminal through the sub-channel.

[0053] Preferably, in this embodiment, each wireless communication terminal uses an internal clock source for time synchronization; the wireless communication terminal can output a second pulse signal to the line protection device for differential synchronization error calculation; thereby achieving synchronization caching of each sub-channel based on the same clock reference. The wireless communication terminal on this side determines the connection relationship of the wireless sub-channel based on the source address and destination address in the wired channel message, and distributes the message to each sub-channel after receiving the message. Each sub-channel is synchronized and cached based on the same clock reference. The time division multiplexing of the wired channel is mapped to the parallel transmission of multiple wireless sub-channels to achieve consistency in the transmission and reception delay of the entire link from the wired channel to the wireless channel.

[0054] The present invention proposes a message transmission method for a multi-terminal differential protection system, which is composed of multiple line protection devices and wireless communication terminals, and constructs an efficient data transmission network through wired and wireless methods. Each line protection device is connected to a wireless communication terminal by wire, and data interaction is achieved between the wireless communication terminals through wireless connection. The method first constructs multiple sub-channels to optimize the transmission efficiency, and then the target wireless communication terminal receives the message from the line protection device and groups it according to preset rules. If the packet message cache reaches the preset time length, the message is quickly and accurately sent to other wireless communication terminals through these multiple sub-channels, and then transmitted to the corresponding line protection device. In addition, all wireless communication terminals perform synchronous caching based on the same clock reference to ensure the accuracy and timeliness of data transmission, and achieve consistency of the transmission and reception delay of the entire link.

[0055] The present invention effectively improves the efficiency and accuracy of message transmission in a multi-terminal differential protection system by constructing multiple sub-channels and parallel wireless transmission. At the same time, the use of the same clock reference for synchronous caching ensures the synchronization and delay consistency of data transmission between channels, thereby greatly optimizing the overall performance of the system and the protection response speed.

[0056] According to one embodiment of the present invention, step S102 includes:

[0057] Step 1: setting a different communication address for each wireless communication terminal;

[0058] Step 2: Based on the communication address, the target wireless communication terminal establishes a communication sub-channel between the target line protection device and other wireless communication terminals.

[0059] In this implementation, each line protection device in the multi-terminal line protection is set with a different communication address, and the message sent contains the address of the device and the target address to be sent. The wireless communication terminal maps a wired channel to multiple wireless sub-channels according to the target address, and sends the message to the corresponding wireless communication terminal through the wireless sub-channel. The time division multiplexing of the wired channel is mapped to the parallel transmission of multiple wireless sub-channels to achieve the consistency of the transmission and reception delay of the entire link from the wired channel to the wireless channel.

[0060] The present invention sets different communication addresses for wireless communication terminals and constructs multiple wireless sub-channels, thereby achieving efficient parallel transmission of messages from wired to wireless throughout the entire link, ensuring the consistency of the transmission and reception delays of the entire link, and improving the response speed and performance of the multi-terminal differential protection system.

[0061] According to an implementation manner of the present invention, the preset rule is: dividing the received messages into multiple message groups based on the message interval, sampling sequence number and target address; specifically,

[0062] Record the current message receiving time, and determine whether the time difference between the current message receiving time and the previous frame message receiving time is greater than the second preset time length; if so, determine that the frame is the first frame message of a group of messages;

[0063] The second preset time length T 1 =T 1 =1 / (N-2)*T int ,

[0064] Where N is the number of terminals of the multi-terminal differential protection, that is, the number of line protection devices in the multi-terminal differential protection system; T int is the sampling sending interval;

[0065] Calculate the difference Δt between the reception time of the nth frame message and the first frame message n_recv , when Δt n_recv <T int If the sampling sequence number of the current message is consistent with the sampling sequence number of the first frame message, and the target address is different from that of the first frame message, the current frame message and the first frame message are determined to be in the same group;

[0066] Among them, n is an integer ranging from 2 to (N-1), and N is the number of multi-terminal differential terminals.

[0067] In this implementation, the wireless communication terminal receives the message sent by the connected protection device, and divides the message into multiple message groups based on the message interval, sampling sequence number and target address. The messages in the group are collected at the same time and sent to other sides. The method of dynamically adjusting the cache start time and duration is used to realize the mapping of wired channel time division multiplexing to wireless multiple sub-channel parallel transmission. The group messages use the same cache start time, and the reception time of the first frame message is t 1_recv As the cache start time of all messages in the message group, the influence of serial transmission delay of wired channel time division multiplexing is eliminated.

[0068] After receiving the message sent by the line protection device, the wireless communication terminal records the receiving time t 1_recv The difference between the current message receiving time and the previous frame message receiving time is greater than T 1 When , the frame is determined to be the first frame message of a group of messages. 1 =1 / (N-2)*T int , where N is the number of multi-terminal differential terminals, T int The sampling interval.

[0069] The receiving time of the subsequent n-th frame message is recorded as t n_recv , calculate the difference Δt between the receiving time of the current message and the first frame message n_recv =t n_recv -t 1_recv , when Δt n_recv <Tint If the sampling sequence number of this message is consistent with the sampling sequence number of the first frame message, and the target address is different from the first frame message, this message and the first frame message are determined to be in the same group. n is an integer ranging from 2 to (N-1), and N is the number of multi-terminal differential terminals.

[0070] The present invention uses preset rules to accurately divide message groups based on message intervals, sampling numbers and target addresses, and dynamically adjusts the cache start time and duration, successfully achieving efficient mapping of wired channel time division multiplexing to wireless multiple sub-channel parallel transmission, eliminating the impact of serial transmission delays, and improving the real-time and accuracy of message transmission, thereby enhancing the overall performance and response speed of the multi-terminal differential protection system.

[0071] According to an embodiment of the present invention, the first preset time length T n_bufset for:

[0072]

[0073] Among them, T n_bufset is the first preset duration; T 1 is the second preset duration; Δt n_recv It is the difference in receiving time between the nth frame message and the first frame message in the message group; the value range of n is 1 to (N-1); N is the number of line protection devices in the multi-terminal differential protection system.

[0074] In this implementation mode, the group messages use the same cache start time, and the receiving time of the first frame message is t 1_recv As the cache start time of all messages in the message group, the influence of serial transmission delay of wired channel time division multiplexing is eliminated. The differentiated message cache time is calculated based on the serial transmission delay difference to eliminate the influence of serial transmission delay of wired channel time division multiplexing. The difference between the receiving time of the nth frame message and the first frame message in the message group is Δt n_recv , the message should be cached for T n_bufset , when t n_buf =T n_bufset When the wireless communication terminal sends the buffered message to the connected protection device.

[0075] The present invention ensures that each message in a message group is time synchronized before wireless transmission by calculating differentiated message cache time, eliminates the influence of serial transmission delay of time division multiplexing of wired channels, and improves the synchronization of message transmission and system response speed.

[0076] Embodiment 2

[0077] Figure 3 This is a flow chart of a method for improving the reliability of multi-terminal differential protection according to an embodiment of the present invention. Figure 1-3As shown, according to an embodiment of the present invention, a method for improving the reliability of multi-terminal differential protection adopts any one of the message transmission methods in Example 1, and the method for improving the reliability of multi-terminal differential protection includes the following steps:

[0078] Step S202: The local wireless communication terminal receives a message sent by the target communication terminal, and parses the received message to obtain a target sampling time;

[0079] Step S204: obtaining the sampling time of the line protection device on the local side;

[0080] Step S206: Determine whether the target sampling time and the local sampling time meet the action conditions; if so, open the differential protection; otherwise, lock the differential protection.

[0081] Preferably, the action condition is: the time difference between the target sampling time and the local sampling time is less than a third preset time length.

[0082] In this embodiment, the wireless communication terminal can output the second pulse signal to the line protection device for differential synchronization error calculation. The line protection device calculates the sampling time based on the second pulse and writes the sampling time into the message. The line protection device receiving the message compares the sampling time of the synchronization data on the local side with the sampling time in the received message. When the sampling time difference is less than the third preset time constant T diff When , it is determined that the synchronization error meets the requirements, otherwise the differential protection is locked. diff The mapping of wired channel time division multiplexing to wireless multiple sub-channel parallel transmission is achieved by dynamically adjusting the cache start time and duration:

[0083] The group messages use the same cache start time and set the receiving time of the first frame message to t 1_recv As the cache start time of all messages in the message group, the influence of serial transmission delay of wired channel time division multiplexing is eliminated.

[0084] Calculate the equivalent time t of the nth frame message in the group message that has been cached based on the same system clock and cache start time n_buf , t n_buf =tt 1_recv , where t is the current time of the wireless terminal system.

[0085] The differentiated message buffer time is calculated based on the serial transmission delay difference to eliminate the impact of the serial transmission delay of the wired channel time division multiplexing. The difference between the receiving time of the nth frame message and the first frame message in the message group is Δt n_recv , the message should be cached for a period of time T n_bufset for:

[0086]

[0087] The value range of n is 1 to (N-1). n_buf =T n_bufset When the wireless communication terminal sends the buffered message to the connected protection device.

[0088] The multi-terminal differential protection reliability improvement method proposed in the present invention ensures the real-time and accuracy of synchronous message transmission by adopting an efficient message transmission mechanism; the present invention utilizes a second pulse signal to synchronize the sampling time, combined with the dynamic adjustment of the cache start time and duration, to eliminate the serial transmission delay of the wired channel time division multiplexing, and realizes the parallel and efficient transmission of wireless multiple sub-channels; the present invention determines the action conditions by comparing the sampling time difference, thereby ensuring the timeliness and accuracy of the differential protection action and improving the stability and reliability of the power system.

[0089] Embodiment 3

[0090] Figure 2 FIG. 1 is a schematic diagram of multi-terminal differential protection connection of a wireless channel based on an embodiment of the present invention. Figure 2 As shown, according to an embodiment of the present invention, a wireless channel construction method suitable for multi-terminal differential protection provides a reliable and convenient communication channel for multi-terminal differential protection.

[0091] The wireless communication terminal receives data from the line protection device, transmits it to the other side wireless communication terminal through the wireless channel, and then sends it to the corresponding line protection device. Figure 2 In the embodiment, wireless communication terminal 1 receives data of line protection 1, and then sends it to wireless communication terminal 2, wireless communication terminal 3...wireless communication terminal N, and then sends it to corresponding line protection device 2, line protection device 3...line protection device N.

[0092] Establishing multiple sub-channels with consistent sending and receiving delays between wireless communication terminals includes the following steps:

[0093] (1) Communication address setting. In multi-terminal line protection, each line protection device is set with a different communication address. The message sent contains the address of the device and the target address. For example, the addresses of line protection 1, 2, 3, and 4 are set to address 1, address 2, address 3, and address 4 respectively. For line protection 1, the target address of its data is address 2, address 3, and address 4.

[0094] (2) The wireless communication terminal receives the message group division of the line protection device. The wireless communication terminal receives the message sent by the connected protection device and divides the message into multiple message groups based on the message interval, sampling sequence number and target address. The messages in the group are collected at the same time and sent to the other sides. For wireless communication terminal 1, 3 frames of messages from line protection 1 will be received, and the target addresses are address 2, address 3, and address 4 respectively. If the sampling sequence numbers in the three messages are the same and the message interval and target address conditions are met, they are considered to be the same group of messages.

[0095] (3) Multiple sub-channel establishment. The wireless communication terminal maps a wired channel to multiple wireless sub-channels according to the target address, and sends the message to the corresponding wireless communication terminal through the wireless sub-channel. The wireless communication terminal determines the wireless sub-channel connection relationship according to the source address and target address in the wired channel message. For example, wireless communication terminal 1 maps a wired channel between wireless communication terminal 1 and line protection 1 to three sub-channels between wireless terminal 1 and wireless terminals 2, 3, and 4.

[0096] (4) The time division multiplexing of the wired channel is mapped into the parallel transmission of multiple wireless sub-channels to achieve the consistency of the transmission and reception delay of the entire link from the wired channel to the wireless channel.

[0097] Taking the case where wireless communication terminal 1 receives the message of line protection 1 as an example, the message group division method is introduced:

[0098] (1) After receiving the message sent by line protection 1, wireless communication terminal 1 records the receiving time t 1_recv The difference between the current message receiving time and the previous frame message receiving time is greater than T 1 When , the frame is determined to be the first frame message of a group of messages. 1 =1 / (N-2)*T int , where N is the number of multi-terminal differential terminals, T int is the sampling sending interval, which can be (1~2) / 1200s.

[0099] (2) The receiving time of the subsequent n-th frame message is recorded as t n_recv , calculate the difference Δt between the receiving time of the current message and the first frame message n_recv =t n_recv -t 1_recv , when Δt n_recv <T int If the sampling sequence number of this message is consistent with the sampling sequence number of the first frame message, and the target address is different from the first frame message, this message and the first frame message are determined to be in the same group. n is an integer ranging from 2 to (N-1), and N is the number of multi-terminal differential terminals.

[0100] The three sub-channels between the wireless communication terminal 1 and the wireless communication terminals 2, 3, and 4 are synchronously cached based on the same clock reference.

[0101] The mapping of wired channel time division multiplexing to wireless multiple sub-channel parallel transmission is achieved by dynamically adjusting the cache start time and duration:

[0102] (1) The group messages use the same cache start time, and the reception time of the first frame message is t 1_recv As the cache start time of all messages in the message group, the influence of serial transmission delay of wired channel time division multiplexing is eliminated.

[0103] (2) Based on the same system clock and cache start time, calculate the equivalent time t of the cached n-th frame message in the group message n_buf , t n_buf =tt 1_recv , where t is the current time of the wireless terminal system.

[0104] (3) Calculate the differentiated message cache time based on the serial transmission delay difference to eliminate the impact of the serial transmission delay of the wired channel time division multiplexing. The difference between the receiving time of the nth frame message and the first frame message in the message group is Δt n_recv , the message should be cached for a period of time T n_bufset for:

[0105]

[0106] The value range of n is 1 to (N-1). n_buf =T n_bufset When the wireless communication terminal sends the buffered message to the connected line protection device.

[0107] The wireless communication terminal can output the second pulse signal to the line protection device for differential synchronization error calculation. The line protection device calculates the sampling time based on the second pulse and writes the sampling time into the message. The line protection device receiving the message compares the sampling time of the synchronization data on its side with the sampling time in the received message. When the sampling time difference is less than T diff When the synchronization error meets the requirement, the differential protection is locked. diff It can be 0.1~0.2ms.

[0108] Embodiment 4

[0109] Figure 4 FIG. 1 is a schematic diagram of the structure of a message transmission system according to an embodiment of the present invention. Figure 4 As shown, according to an embodiment of the present invention, a message transmission system includes:

[0110] A construction module 10 is used to construct multiple sub-channels for transmitting messages;

[0111] The grouping module 20, the target wireless communication terminal receives the message sent by the target line protection device, and groups the received message according to a preset rule to obtain a message group; wherein the target line protection device is a line protection device connected to the target wireless communication terminal by wire;

[0112] The transmission module 30 determines whether the message group has been cached for a first preset time period; if so, the target wireless communication terminal sends the message group to other wireless communication terminals through multiple sub-channels.

[0113] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working process of the system described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here.

[0114] The message transmission system proposed in the present invention realizes fast and accurate transmission of messages in wireless communication by constructing multiple sub-channels and using a grouping module to efficiently group messages, combined with a dynamic cache mechanism of the transmission module. The system effectively improves the real-time performance and reliability of message transmission, and provides solid technical support for multi-terminal differential protection of distributed power sources.

[0115] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

[0116] It should be understood that the size of the serial numbers of each step in the content of the invention and the embodiments of the present invention does not absolutely mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.

Claims

1. A message transmission method, applied to a multi-terminal differential protection system having a plurality of line protection devices, each line protection device is connected to a wireless communication terminal by wire, and the wireless communication terminals are connected to each other by wireless; characterized in that: The message transmission method comprises the following steps: Construct multiple subchannels for transmitting messages; The target wireless communication terminal receives the message sent by the target line protection device, and groups the received message according to a preset rule to obtain a message group; wherein the target line protection device is a line protection device connected to the target wireless communication terminal by wire; It is determined whether the message group has been cached for a first preset time period; if so, the target wireless communication terminal sends the message group to other wireless communication terminals through the multiple sub-channels.

2. The message transmission method according to claim 1, characterized in that: Constructing multiple subchannels for transmitting messages includes the following steps: Setting a different communication address for each wireless wireless communication terminal; Based on the communication address, the target wireless communication terminal establishes a communication sub-channel between the target line protection device and other wireless communication terminals.

3. The message transmission method according to claim 1, characterized in that: The preset rule is: dividing the received messages into a plurality of message groups based on the message interval, the sampling sequence number and the target address.

4. The message transmission method according to claim 3, characterized in that: Calculate the difference Δt between the reception time of the nth frame message and the first frame message n_recv , when Δt n_recv <T int If the sampling sequence number of the current message is consistent with the sampling sequence number of the first frame message, and the target address is different from that of the first frame message, the current frame message and the first frame message are determined to be in the same group; Where n is an integer ranging from 2 to (N-1), N is the number of terminals of the multi-terminal differential, T int The sampling interval.

5. The message transmission method according to claim 3, characterized in that: Record the current message receiving time, and determine whether the time difference between the current message receiving time and the previous frame message receiving time is greater than the second preset time length; if so, determine that the frame is the first frame message of a group of messages; The second preset time length T1 is: T1 = 1 / (N-2)*T int , Where N is the number of terminals of the multi-terminal differential, T int The sampling interval.

6. The message transmission method according to claim 1, characterized in that: The first preset time length T n_bufset for: Among them, T n_bufset is the first preset duration; T1 is the second preset duration; Δt n_recv It is the difference in receiving time between the nth frame message and the first frame message in the message group; the value range of n is 1 to (N-1); N is the number of multi-terminal differential terminals.

7. The message transmission method according to claim 1, characterized in that: Each wireless communication terminal uses an internal clock source for time synchronization; Each wireless communication terminal outputs a pulse-per-second signal to the line protection device connected thereto for use in differential synchronization error calculation.

8. A method for improving the reliability of multi-terminal differential protection, using the message transmission method according to any one of claims 1 to 7, characterized in that: The multi-terminal differential protection reliability improvement method comprises the following steps: The local wireless communication terminal receives the message sent by the target communication terminal, and parses the received message to obtain the target sampling time; Obtain the sampling time of the line protection device on this side; Determine whether the target sampling time and the local sampling time meet the action condition; If satisfied, open differential protection is executed; otherwise, lock differential protection.

9. The method for improving the reliability of multi-terminal differential protection according to claim 8, characterized in that: The action conditions are: The time difference between the target sampling time and the local sampling time is less than a third preset time length.

10. A message transmission system, characterized in that: include: A construction module is used to construct multiple sub-channels for transmitting messages; A grouping module, wherein the target wireless communication terminal receives a message sent by a target line protection device, and groups the received message according to a preset rule to obtain a message group; wherein the target line protection device is a line protection device connected to the target wireless communication terminal by wire; The judging module judges whether the message group has been cached for a first preset time period; if so, the target wireless communication terminal sends the message group to other wireless communication terminals through the multiple sub-channels.

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