Time-sensitive network traffic scheduling method for intelligent substation

Abstract

The invention relates to an intelligent substation time-sensitive network traffic scheduling method, which belongs to the technical field of time-sensitive network traffic scheduling, and comprises the following steps: S1, carrying out time synchronization on secondary device equipment of an intelligent substation and a TSN network; s2, business data streams in the substation automation system are divided into three classes, and the relative deadline of each class is set; s3, using flow filtering and managing PSFP configuration, so that data frames with close deadline are inserted into a higher priority queue; s4, constructing a transmission mechanism of the sending node; s5, constructing a transmission mechanism of the switch; and S6, setting the number N of the flow doors and the time interval u of calculating the IPV by the flow doors.

Description

Technical Field

[0001] The present invention belongs to the technical field of time-sensitive network traffic scheduling, and relates to a time-sensitive network traffic scheduling method for an intelligent substation. Background Art

[0002] With the accelerated construction of new power systems, the status of communication networks in power systems has become increasingly important. IEC61850 has become the reference standard for substation automation systems in smart grids. The dramatic increase in the amount of smart grid business data has also increased the requirements for low latency and high reliability of control information transmission. The high proportion of power electronic equipment and the massive access of IoT terminals have challenged the bandwidth, latency, reliability and other performance of traditional communication systems. At this time, the traditional Ethernet "best effort" transmission mode can no longer meet the technical requirements of the smart grid field.

[0003] Time-sensitive networks achieve zero-congestion packet loss transmission through a series of protocol standards, provide low latency and jitter with upper bound guarantees, and provide deterministic transmission guarantees for time-sensitive traffic. They are widely used in production practices in the industrial field. If TSN-related features are applied to smart substation networking, building a time-sensitive network can not only achieve rapid fault location and repair by reducing transmission latency and jitter, but also improve the robustness of the power grid and ensure that key services are not interfered with to a certain extent. At present, promoting the deep integration of time-sensitive networks and substation automation can perfectly meet the low latency, low jitter and high reliability transmission requirements of smart substations.

[0004] The "three-layer one-network" networking solution for smart substations based on the time-sensitive network TSN refers to the mixed transmission of multiple types of messages such as SV, GOOSE, MMS, clock synchronization, etc. in the same network of smart substations, connecting all IEDs in the station to one network, and directly accessing information across layers and intervals to achieve information sharing across the station. There are many types of traffic in the communication network of smart substations, including sudden event messages and periodic messages with low latency requirements. The mixed transmission of these traffic usually brings uncertainty problems.

[0005] In the substation automation system, some important GOOSE-type information belongs to event-triggered information (non-periodic). If bandwidth is allocated periodically, it is easy to waste resources and limit the ability to expand more power services. At the same time, such applications are usually responsible for transmitting more important events, such as real-time trip signals and interval logic interlocks. The generation of these applications requires limited and very low end-to-end latency. This delay ranges from tens of microseconds to tens of milliseconds, but as of now, although time-sensitive networks allow different types of traffic to be transmitted on the same channel, TSN's support for different categories of ET real-time streams is limited. To address this problem, traditional TSN-TAS offline scheduling algorithms usually use a method of giving higher priority to critical data streams to ensure low-latency transmission of critical data. Even if different TSN scheduling algorithms are used, when multiple flows of the same priority are generated at the same time or burst flows are generated, conflicts and interference will also occur, resulting in uncontrollable queuing delays and jitters. In severe cases, packet loss may occur, such as Figure 1 shown. Summary of the invention

[0006] In view of this, an object of the present invention is to provide an online scheduling method (TSN-QCI) based on the deadline of key business traffic of a substation.

[0007] In order to achieve the above object, the present invention provides the following technical solutions:

[0008] A method for scheduling time-sensitive network traffic in a smart substation comprises the following steps:

[0009] S1: Synchronize the time between the secondary devices of the smart substation and the TSN network;

[0010] S2: Divide the business data flow in the substation automation system into three categories and set the relative deadline for each category;

[0011] S3: Use flow filtering and manage PSFP configuration so that data frames with close deadlines are inserted into higher priority queues;

[0012] S4: Construct the transmission mechanism of the sending node;

[0013] S5: Build the transmission mechanism of the switch;

[0014] S6: Set the number of flow gates N and the flow gate change time interval u.

[0015] Further, step S1 specifically includes the following steps:

[0016] S11: The synchronous network port of the substation satellite synchronization device sends a B code signal to synchronize the time with the protection and measurement and control integrated device;

[0017] S12: The synchronization network port of the substation satellite synchronization device sends a PTP message, and the TSN switch receives the PTP message to complete synchronization with the satellite master clock;

[0018] S13: The TSN switch recalculates the synchronization information and sends it to the integrated device, completes the clock synchronization of the integrated device, and finally completes the global time synchronization.

[0019] Further, the relative deadline in step S2 is expressed as D i , which is the end-to-end delay, indicating that the frame must be generated and transmitted before this time; relative deadline D i It is expressed as follows:

[0020] D i =t dst -t src

[0021] where t src Indicates the frame sending time, t dst Indicates the frame arrival time.

[0022] Further, in step S2, the service data flow in the substation automation system is divided into three categories: Goose, SV and MMS, and different D i .

[0023] Further, in step S3, the flow filtering and management PSFP is configured, and the IPV value in the flow gating instance table is set, so that the IPV value of the frame is changed hop by hop as the deadline approaches, thereby increasing the frame priority.

[0024] Further, the transmission mechanism of the sending node in step S4 includes:

[0025] S41: Classify the flows in the power scenario, preset the number of transmission queues Q, the transmission queue time interval u and the relative deadline D i ;

[0026] S42: The sending node generates a frame and assigns a VID and a PCP value of an Ethernet VLAN tag to the frame;

[0027] S43: The sending node sets the IPV to 0 and performs queue mapping at the egress port according to the PCP value of the frame.

[0028] Furthermore, for the jth frame f of the i-th stream generated by the sending node i,j , its VID value is V i,j is an integer in the range {0,...,N} and is calculated as follows:

[0029]

[0030] Where b is the time required to transmit 1 bit; the cycle time is defined as T C =N×u,T C Represents the time range of scheduling; D i Indicates a relative deadline;

[0031] Frame f i,j The PCP value is calculated as follows:

[0032]

[0033] t represents the current time, V ij Indicates VID, T C represents the time range of scheduling, and b represents the time required to transmit 1 bit.

[0034] Further, the transmission mechanism of the switch in step S5 includes:

[0035] S51: The switch node receives a frame, identifies a frame VID value carried by the frame, and associates a flow gate with the frame based on the frame VID value;

[0036] S52: The frame passes through the flow gate and enters the corresponding transmission queue according to the internal priority IPV value calculated by the flow gate, waiting for transmission;

[0037] S53: The frames entering the queue are transmitted in order based on the strict priority transmission selection algorithm.

[0038] Further, in step S5, for each VID, the flow gate control list determines the priority transfer through IPV, and the function of IPV is as follows:

[0039]

[0040] In the formula, s(t) = t / u, (t < D i ), t represents the current time, G represents the identifier of the flow gate, and N represents the number of flow gates in TSN-QCI; the above function is used to allocate IPVs among the flow gates to achieve periodic transfer of priorities.

[0041] Further, in step S6, the number of flow gates N depends on the hardware structure and software and firmware configuration of the switch and is set to the maximum value supported by the switch; u is set to a value less than 100 μs.

[0042] The beneficial effect of the present invention is that the previous substation dispatching method usually dispatches periodic traffic (TT) and ignores the processing of non-periodic burst traffic (ET). In the power system network, the more important GOOSE traffic is non-periodic traffic, which ensures the safe operation of the power system. While the present method can dispatch TT traffic, it also considers the transmission of non-periodic burst traffic. Through the present method, not only the transmission of TT traffic can be completed, but also the transmission of non-TT traffic with delay requirements can be completed.

[0043] Other advantages, objectives and features of the present invention will be described in the following description to some extent, and to some extent, will be obvious to those skilled in the art based on the following examination and study, or can be taught from the practice of the present invention. The objectives and other advantages of the present invention can be realized and obtained through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention will be described in detail below in conjunction with the accompanying drawings, wherein:

[0045] Figure 1 Transmit conflicting instances for traffic;

[0046] Figure 2 Time synchronization process for smart substation;

[0047] Figure 3 Provides flow filtering and management functions;

[0048] Figure 4 It is the transmission process diagram of the end device;

[0049] Figure 5 It is a dynamic change diagram of the flow gate control list;

[0050] Figure 6 Figure 2 is a diagram of the transmission process of the switch. DETAILED DESCRIPTION

[0051] The following describes the embodiments of the present invention by specific examples, and those skilled in the art can easily understand other advantages and effects of the present invention from the contents disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments only illustrate the basic concept of the present invention in a schematic manner, and the following embodiments and features in the embodiments can be combined with each other without conflict.

[0052] It should be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present invention, and thus the drawings only show components related to the present invention rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0053] In the following description, numerous details are discussed to provide a more thorough explanation of the embodiments of the present invention. However, it is obvious to those skilled in the art that the embodiments of the present invention can be implemented without these specific details. In other embodiments, well-known structures and devices are shown in the form of block diagrams rather than in detail to avoid making the embodiments of the present invention difficult to understand.

[0054] The present invention provides a method for online scheduling of time-sensitive network traffic in a smart substation, comprising the following steps:

[0055] S1: Synchronize the time of the secondary devices of the smart substation with the TSN network. The focus of the substation time synchronization upgrade is to use high-precision hardware timestamps and synchronization algorithms, which can provide higher time accuracy when integrating networking and scheduling. The point-to-point direct B-code signal timing used in the original substation process layer is transformed. First, synchronize the satellite synchronization device with the protection and measurement control integrated device and the digital relay protection tester, and then synchronize the satellite synchronization device with the best master clock of the TSN switch, and then complete the clock synchronization with the integrated device of the TSN switch to achieve global time synchronization between the secondary devices of the smart substation based on the three-layer one-network networking method and the TSN switch. The time synchronization process of the smart substation based on TSN is as follows Figure 2 shown.

[0056] In this section, time synchronization is divided into the following three steps:

[0057] S11: The synchronous network port of the substation satellite synchronization device sends a B code signal to synchronize the time with the protection and measurement and control integrated device;

[0058] S12: The substation satellite synchronization device sends a PTP message (AS synchronization signal) through the synchronization network port, and the TSN switch receives the PTP message to complete synchronization with the satellite master clock.

[0059] S13: The TSN switch recalculates the synchronization information and sends it to the integrated device, completes the clock synchronization of the integrated device, and finally completes the global time synchronization.

[0060] S2: TSN-QCI deadline (D i ) settings. iRelative deadline (D) indicates the relative deadline of the frame (end-to-end delay), indicating that the frame must be generated and transmitted before this time to meet the real-time requirements of the power system. i ) involves two key factors:

[0061] D i =t dst -t src

[0062] (1) Frame transmission time (t src ): Indicates the arrival time of a frame in the system. It indicates when the frame enters the system and begins to wait for transmission or processing. The frame arrival time is usually determined by the input traffic and timing characteristics of the system.

[0063] (2) Frame arrival time (t dst ): It indicates the total delay of the frame in the network, which depends on the sending delay, propagation delay, processing delay and queuing delay of data transmission. It is a very important performance indicator in the network.

[0064] At present, in the IEC61850-90 standard, smart substations divide messages into eight categories based on time requirements, as shown in Table 1. Determined requirements are made for transmission delays. The guarantee of delay is also very important for power grid protection and monitoring.

[0065] Table 1

[0066]

[0067]

[0068] Relative deadline D i : This is a time requirement associated with a specific flow, indicating how long a frame must be transmitted from the time it arrives. Relative deadlines are usually defined by the system designer based on the real-time requirements of the application.

[0069] In combination with the specific operation of the substation automation system network, the present invention sets the deadline of the IEC 61850 service data flow in the substation automation system to three categories from the perspective of deterministic network transmission. i 3ms, D of SV message i The D of MMS message is 3ms. i The cut-off time D is 100ms. i The setting is mainly used as the input for subsequent calculations to ensure that the end-to-end delay is within the deadline.

[0070] S3: In TSN-QCI, a specific PSFP (stream filtering and management) configuration is used so that as the deadline approaches, the IPV changes hop by hop, increasing the frame priority (this is achieved by changing the IPV in each flow gating list accordingly), so that data frames with approaching deadlines are inserted into higher priority queues and transmitted faster.

[0071] PSFP consists of three components, such as Figure 3 As shown in the figure, they are flow filter, flow gate and flow meter. Each component has a corresponding parameter instance table, namely flow filter instance table, flow gate instance table and flow meter instance table. The main function of the flow filter instance table is to match the incoming frame according to its VLAN ID (VID) and the Stream ID and Priority parameters in the flow filter to find the corresponding flow filter. The flow gate instance table mainly consists of two parameters, StreamGateState and IPV, namely the gate state and internal priority. When configuring PSFP, the queued frames are mainly mapped to the queue according to the IPV value in the flow gate instance table. The flow meter instance table is mainly responsible for metering the flow. The flow filter instance table is an ordered list consisting of multiple flow filters. The flow entering the flow filter is assigned flow gate and flow meter to achieve flow filtering and supervision.

[0072] The setting range of the internal priority IPV in the flow gate is as follows:

[0073] (1) Zero value: When a frame passes through flow gating, the priority value PCP associated with the frame is used to determine the traffic category of the frame (that is, the queue is mapped by the PCP value).

[0074] (2) Internal priority value: When a frame passes through flow gating, the queue is mapped mainly through the set IPV value.

[0075] TSN-QCI provides two frame transmission mechanisms, one for the sending node and the other for the intermediate nodes (switches). These mechanisms differ in the parameters that drive the frame insertion queue, the sending node uses the PCP value, and the switch uses the IPV value. The sending node uses a software transmission mechanism that calculates the PCP and VID values ​​for each frame and transmits the frame to the Ethernet port within the calculated time window. No specific PSFP configuration is used in the Ethernet port of the sending node, and the queue to transmit the frame is selected based on the defined strict priority (PCP). The switch uses a specific PSFP configuration that allows the queue where the frame is inserted to be changed hop by hop based on the IPV of the frame. In the switch, the control list of each flow gate is configured to increase the frame priority when the deadline is approaching. This is achieved by changing the IPV in the control list of each flow gate accordingly (IPV changes over time).

[0076] S4: TSN-QCI transmission mechanism at the sending node. In TSN-QCI, the end node generates frames and assigns the VID and PCP values ​​of the Ethernet VLAN tags to these frames. i,j ) is generated, its absolute deadline d i,j The frame transmission time t src and the relative deadline D of the i-th flow i In a real-time system, the generation and transmission of frames must be carried out strictly according to the time requirements to ensure the reliability and real-time performance of the system. i,j , its VID value is V i,j is a mapping of absolute deadlines, which are integers in the range {0,...,N}, calculated as follows:

[0077]

[0078] Where b is the time required to transmit 1 bit. The cycle time is defined as T C =N×u,T C represents the time range of the schedule. u represents the time interval of the flow gate change, and the cycle time will move every u, thereby gradually expanding the schedule to frames with larger absolute deadlines. i Indicates a relative deadline.

[0079] Before transmitting the frame to the Ethernet port, the sending node also assigns a PCP value to the frame, which is calculated as follows:

[0080]

[0081] t represents the current time, V ij represents VID, Q is the number of queues, T C The PCP value represents the time range of the schedule, and b represents the time required to transmit 1 bit. i,j Calculated at the sending node, it determines the frame f i,j The transmission queue to be inserted. In addition, in TSN-QCI, the PSFP in the terminal node does not need to be set. Figure 4 shown.

[0082] S5: Transmission mechanism of TSN-QCI in switches. In TSN-QCI, frames arriving at Ethernet ports are assigned to a flow gate according to their VID value. Each flow gate is identified by a VID value. The first VID starts with VID0, which is the VID mapped to flow gate number 0. Other flows are identified with consecutive values, namely VID NMapped to flow gate N. Each flow gate maintains an IPV that specifies the transmit queue to be assigned to incoming frames.

[0083] The IPV changes instantaneously at a fixed time within the flow gate cycle. The fixed time here is called a time unit (u). In general, the shorter the time unit, the higher the granularity of the absolute deadline that can be encoded, and the higher the precision. This allows the association between flow gates and transmission queues to be changed dynamically, such as Figure 5 As shown in Figure 1, TSN-QCI exploits this property to implement deadline-based scheduling within the switch. In this way, the highest priority frame is assigned to the frame with the closest absolute deadline, and if multiple frames are enqueued to the same transmission queue, they will be transmitted in FIFO order.

[0084] For each VID, the flow gate control list will transfer the priority, which is determined by IPV. The function of IPV is as follows:

[0085]

[0086] In the formula, s(t) = t / u, (t < D i ), t represents the current time, G represents the identifier of the flow gate, Q represents the number of queues, and N represents the number of flow gates in TSN-QCI. The purpose of this function is to allocate IPVs between flow gates to achieve periodic priority transfer. The transmission process of TSN-QCI in the switch is as follows Figure 6 shown.

[0087] S6: TSN-QCI configuration parameters.

[0088] TSN-QCI is transmitted based on the absolute deadline of the frame, so no complex network configuration is required. The only two parameters that need to be calculated are the number of flow gates to use, N, which depends on the hardware adopted and should be set as high as possible, and the time unit u, which is the interval at which the flow gate calculates its IPV.

[0089] According to the IEEE 802.1Q standard, the number of queues per Ethernet port is limited to eight. Therefore, frames with different absolute deadlines may end up in the same queue. A larger N value provides a finer granularity of absolute deadlines in the VID, which enables better differentiation of frames mapped to the same queue. In TSN-QCI, all frames change their priority according to their IPV on a hop-by-hop basis. In particular, frames with higher VIDs will increase their priority faster than frames with lower VIDs. Therefore, for a given number of hops, it is possible to end up being assigned to different queues on the next hop depending on the VID. Therefore, a larger N value needs to be selected, which complements the priority transformation mechanism well. The number of flow gates N mainly depends on the hardware structure of the switch as well as the software and firmware configuration. N is set as high as possible, and is generally taken as the maximum value supported by the switch.

[0090] The u parameter affects the granularity of scheduling. When the u value decreases, the granularity improves and the end-to-end delay decreases. When the u value increases, it means that the number of frames that will be scheduled with the same priority may also increase if their arrival times are the same. In the smart substation network, the deadline for more important information messages is 3ms. In order to ensure the fine granularity of scheduling, u is usually taken as 100μs. For more sophisticated scenarios, u can be smaller.

[0091] In the above embodiments, the description's reference to "this embodiment" indicates that a particular feature, structure, or characteristic described in conjunction with the embodiment is included in at least some embodiments, but not necessarily all embodiments. Multiple occurrences of "this embodiment" do not necessarily all refer to the same embodiment.

[0092] In the above-described embodiments, although the invention has been described in conjunction with specific embodiments of the invention, many substitutions, modifications, and variations of these embodiments will be apparent to those of ordinary skill in the art based on the foregoing description. For example, other storage structures (e.g., dynamic RAM (DRAM)) may use the embodiments discussed. Embodiments of the invention are intended to encompass all such substitutions, modifications, and variations that fall within the broad scope of the appended claims.

[0093] This embodiment further provides a computer-readable storage medium on which a computer program is stored. When the program is executed by a processor, any one of the methods in this embodiment is implemented.

[0094] This embodiment also provides an electronic terminal, including: a processor and a memory;

[0095] The memory is used to store a computer program, and the processor is used to execute the computer program stored in the memory, so that the terminal executes any one of the methods in this embodiment.

[0096] The computer-readable storage medium in this embodiment can be understood by ordinary technicians in this field: all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to the computer program. The aforementioned computer program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, magnetic disk or optical disk and other media that can store program codes.

[0097] The electronic terminal provided in this embodiment includes a processor, a memory, a transceiver and a communication interface. The memory and the communication interface are connected to the processor and the transceiver and complete communication with each other. The memory is used to store computer programs, the communication interface is used to communicate, and the processor and the transceiver are used to run computer programs so that the electronic terminal executes each step of the above method.

[0098] In this embodiment, the memory may include a random access memory (RAM), and may also include a non-volatile memory (non-volatile memory), such as at least one disk memory.

[0099] The above-mentioned processor can be a general-purpose processor, including a central processing unit (CPU), a network processor (NP), etc.; it can also be a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0100] The present invention can be used in many general or special computing system environments or configurations, such as personal computers, server computers, handheld or portable devices, tablet devices, multiprocessor systems, microprocessor-based systems, set-top boxes, programmable consumer electronic devices, network PCs, minicomputers, mainframe computers, distributed computing environments including any of the above systems or devices, and the like.

[0101] The present invention may be described in the general context of computer-executable instructions executed by a computer, such as program modules. Generally, program modules include routines, programs, objects, components, data structures, etc. that perform specific tasks or implement specific abstract data types. The present invention may also be practiced in distributed computing environments where tasks are performed by remote processing devices connected through a communication network. In a distributed computing environment, program modules may be located in local and remote computer storage media, including storage devices.

[0102] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution, which should be included in the scope of the claims of the present invention.

Claims

1. A method for scheduling time-sensitive network traffic in a smart substation, characterized by: The following steps are involved: S1: Synchronize the time between the secondary devices of the smart substation and the TSN network; S2: Divide the business data flow in the substation automation system into three categories and set the relative deadline for each category; S3: Use flow filtering and manage PSFP configuration so that data frames with close deadlines are inserted into higher priority queues; S4: Construct the transmission mechanism of the sending node; S5: Build the transmission mechanism of the switch; S6: Set the number of flow gates N and the flow gate change time interval u.

2. The method for scheduling traffic in a time-sensitive network of a smart substation according to claim 1, characterized in that: Step S1 specifically includes the following steps: S11: The synchronous network port of the substation satellite synchronization device sends a B code signal to synchronize the time with the protection and measurement and control integrated device; S12: The synchronization network port of the substation satellite synchronization device sends a PTP message, and the TSN switch receives the PTP message to complete synchronization with the satellite master clock; S13: The TSN switch recalculates the synchronization information and sends it to the integrated device, completes the clock synchronization of the integrated device, and finally completes the global time synchronization.

3. The method for scheduling traffic in a time-sensitive network of a smart substation according to claim 1, characterized in that: The relative deadline in step S2 is represented by D i , which is the end-to-end delay, indicating that the frame must be generated and transmitted before this time; relative deadline D i It is expressed as follows: D i =t dst -t src where t src Indicates the frame sending time, t dst Indicates the frame arrival time.

4. The method for scheduling traffic in a time-sensitive network of a smart substation according to claim 3 is characterized in that: In step S2, the service data flow in the substation automation system is divided into three categories: Goose, SV and MMS, and different D i .

5. The method for scheduling traffic in a time-sensitive network of a smart substation according to claim 1, characterized in that: In step S3, the flow filtering and management PSFP is configured, and the IPV value in the flow gating instance table is set so that the IPV value of the frame is changed hop by hop as the deadline approaches, thereby increasing the frame priority.

6. The method for scheduling traffic in a time-sensitive network of a smart substation according to claim 1, characterized in that: The transmission mechanism of the sending node in step S4 includes: S41: Classify the flows in the power scenario, preset the number of transmission queues Q, the flow gate change time interval u and the relative deadline D i ; S42: The sending node generates a frame and assigns a VID and a PCP value of an Ethernet VLAN tag to the frame; S43: The sending node sets the IPV to 0 and performs queue mapping at the egress port according to the PCP value of the frame.

7. The method for scheduling traffic in a time-sensitive network of a smart substation according to claim 6 is characterized in that: For the jth frame f of the i-th stream generated by the sending node i,j , its VID value is V i,j is an integer in the range {0,...,N} and is calculated as follows: In the formula, b represents the time required to transmit 1 bit; The cycle time is defined as T C =N×u,T C Represents the time range of scheduling; D i Indicates a relative deadline; Frame f i,j The PCP value is calculated as follows: t represents the current time, V ij Indicates VID, T C represents the time range of scheduling, and b represents the time required to transmit 1 bit.

8. The method for scheduling traffic in a time-sensitive network of a smart substation according to claim 1, characterized in that: The transmission mechanism of the switch in step S5 includes: S51: The switch node receives a frame, identifies a frame VID value carried by the frame, and associates a flow gate with the frame based on the frame VID value; S52: The frame passes through the flow gate and enters the corresponding transmission queue according to the internal priority IPV value calculated by the flow gate, waiting for transmission; S53: The frames entering the queue are transmitted in order based on the strict priority transmission selection algorithm.

9. The method for scheduling traffic in a time-sensitive network of a smart substation according to claim 1, characterized in that: In step S5, for each VID, the flow gate control list determines the priority transfer through IPV, and the function of IPV is as follows: In the formula, s(t) = t / u, (t < D i ), t represents the current time, G represents the identifier of the flow gate, and N represents the number of flow gates in TSN-QCI; the above function is used to allocate IPVs among the flow gates to achieve periodic transfer of priorities.

10. The method for scheduling traffic in a time-sensitive network of a smart substation according to claim 1, characterized in that: In step S6, the number of flow gates N depends on the hardware structure and software and firmware configuration of the switch and is set to the maximum value supported by the switch; u is set to a value less than 100 μs.

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