A multi-scenario delay analysis method and system for time-sensitive networks in smart substations

Abstract

The present invention relates to a multi-scenario delay analysis method and system for a time-sensitive network of a smart substation, and relates to the field of substation communication technology. The method includes: generating a smart substation traffic delay calculation model according to the network structure of the smart substation and the internal structure of a time-sensitive network TSN switch; in a single protection window scenario, determining the transmission delay of GOOSE traffic and MMS traffic after traffic scheduling by combining a time-aware shaper TAS and a credit-based shaper CBS mechanism; in a multi-protection window scenario, determining the transmission delay of GOOSE traffic and MMS traffic; in a multi-hop network scenario, determining the transmission delay of GOOSE traffic and MMS traffic based on the smart substation traffic delay calculation model. This method can perform accurate delay analysis on the traffic transmission process of the substation and ensure the transmission performance of critical traffic.

Description

Technical Field

[0001] The present invention relates to the field of substation communication technology, and in particular to a multi-scenario delay analysis method and system for a time-sensitive network of an intelligent substation. Background Art

[0002] The demand for power companies to provide customers with performance-guaranteed services is growing, and the construction of smart grids has become the key to the development of power systems. As an important node of the smart grid, the smart substation has a high-performance internal communication network with guaranteed latency as the basis for its development. To ensure standardized communication in substations, substations currently use the IEC 61850 unified communication standard. IEC 61850 is the only international standard for substation automation systems, which standardizes data naming, data definition, self-description characteristics of equipment, equipment behavior and common configuration language. The IEC 61850 protocol includes three types of traffic: sampled measurement value (SMV) traffic, general object-oriented substation event (GOOSE) traffic and manufacturing message specification (MMS) traffic. Among them, SMV traffic is time-triggered periodic traffic, while GOOSE and MMS traffic are non-periodic traffic combining time triggering and event triggering. The use of TSN technology can ensure the determinism of SMV traffic transmission. However, the delay of GOOSE and MMS traffic will be affected by many factors such as different transmission mechanisms, network structures and network environments within TSN technology. Delay analysis will be more complicated in multi-hop transmission scenarios. Therefore, smart substation networks are in urgent need of accurate and effective delay analysis methods.

[0003] At present, most of the research on GOOSE and MMS traffic delay analysis focuses on the network calculation model. The worst-case delay of the traffic is determined based on the maximum horizontal distance between the arrival curve and the service curve in the network calculation model. It does not consider the different transmission congestion situations faced by different types of traffic in substations and various scenarios of substation transmission. These congestion is caused by the TSN transmission mechanism and network environment. Summary of the invention

[0004] The main purpose of the present invention is to overcome the shortcomings and deficiencies of the prior art and to provide a multi-scenario delay analysis method and system for a time-sensitive network of a smart substation, which can perform accurate delay analysis on the flow transmission process of the substation and ensure the transmission performance of critical flow.

[0005] According to one aspect of the present invention, the present invention provides a multi-scenario delay analysis method for a smart substation time-sensitive network, the method comprising the following steps:

[0006] According to the network structure of the smart substation and the internal structure of the time-sensitive network TSN switch, a smart substation traffic delay calculation model is generated;

[0007] In the single protection window scenario, the transmission delay of the general object-oriented substation event GOOSE traffic and the manufacturing message specification MMS traffic after traffic scheduling by combining the time-aware shaper TAS and the credit-based shaper CBS mechanism is determined;

[0008] Determine the transmission delay of GOOSE traffic and MMS traffic in the multi-protection window scenario;

[0009] In a multi-hop network scenario, the transmission delay of GOOSE traffic and MMS traffic is determined based on the smart substation traffic delay calculation model.

[0010] Preferably, the smart substation flow delay calculation model includes:

[0011] The data frame τ of GOOSE traffic and MMS traffic i The delay during transmission is expressed as:

[0012] T NPT (τ i )=T FIFO (τ i )+T LP +T HP +T TRANS

[0013]

[0014] Among them, T FIFO (τ i ) represents the data frame τ i The queuing delay caused by the priority queue first-in-first-out strategy, T LP Indicates low priority delay, T HP Indicates high priority delay, T TRANS represents the transmission delay, C i Indicates that the TSN switch transmits data frame τ i The delay generated, C j Indicates that the TSN switch transmits data frame τ j The delay generated, sp(i) represents the delay between the TSN switch and the data frame τ i The set of all frames in the same priority queue, S j represents the credit reduction rate when sending traffic j, I j represents the idle time credit accumulation rate of flow j.

[0015] Preferably, in a single protection window scenario, determining the transmission delay of GOOSE traffic and MMS traffic after traffic scheduling by combining a time-aware shaper TAS and a credit-based shaper CBS mechanism comprises:

[0016] Data frames τ of GOOSE traffic and MMS traffic in a single protection window scenario i The total latency inside a TSN switch is:

[0017]

[0018] Among them, L SMV Indicates the length of the protection flow time window used to transmit SMV traffic, L GB Indicates the length of the guard band, L recover Indicates credit recovery time.

[0019] Preferably, in the multi-protection window scenario, determining the transmission delay of GOOSE traffic and MMS traffic includes:

[0020] Data frames τ of GOOSE traffic and MMS traffic in the multi-protection window scenario i The latency inside a TSN switch is:

[0021]

[0022] in, is the length of the kth protection time window, and m represents the number of times the original TAS time window is divided in a certain transmission.

[0023] Preferably, in a multi-hop network scenario, based on the smart substation traffic delay calculation model, determining the transmission delay of GOOSE traffic and MMS traffic includes:

[0024] In the single protection window scenario, the data frames τ of GOOSE traffic and MMS traffic i The total delay for multi-hop transmission is:

[0025]

[0026] In the multi-protection window scenario, the data frame τ of GOOSE traffic and MMS traffic i The total delay for multi-hop transmission is:

[0027]

[0028] Among them, WCN represents the number of TAS super cycles that data frame transmission needs to wait for, and n is the number of output ports of the TSN switch.

[0029] According to another aspect of the present invention, the present invention also provides a multi-scenario delay analysis system for a time-sensitive network of a smart substation, the system comprising:

[0030] A model generation module is used to generate a smart substation traffic delay calculation model based on the network structure of the smart substation and the internal structure of the time-sensitive network TSN switch;

[0031] The first determination module is used to determine the transmission delay of the substation event GOOSE flow and the manufacturing message specification MMS flow oriented to the general object after the flow scheduling combined with the time-aware shaper TAS and the credit-based shaper CBS mechanism in the single protection window scenario;

[0032] The second determination module is used to determine the transmission delay of GOOSE traffic and MMS traffic in a multi-protection window scenario;

[0033] The third determination module is used to determine the transmission delay of GOOSE traffic and MMS traffic based on the smart substation traffic delay calculation model in a multi-hop network scenario.

[0034] Preferably, the model generation module generates the intelligent substation flow delay calculation model including:

[0035] The data frame τ of GOOSE traffic and MMS traffic i The delay during transmission is expressed as:

[0036] T NPT (τ i )=T FIFO (τ i )+T LP +T HP +T TRANS

[0037]

[0038] Among them, T FIFO (τ i ) represents the data frame τ i The queuing delay caused by the priority queue first-in-first-out strategy, T LP Indicates low priority delay, T HP Indicates high priority delay, T TRANS represents the transmission delay, C i Indicates that the TSN switch transmits data frame τ i The delay generated, C j Indicates that the TSN switch transmits data frame τ j The delay generated, sp(i) represents the delay between the TSN switch and the data frame τ i The set of all frames in the same priority queue, S j represents the credit reduction rate when sending traffic j, I j represents the idle time credit accumulation rate of flow j.

[0039] Preferably, the first determination module determines the transmission delay of GOOSE traffic and MMS traffic after traffic scheduling by combining the time-aware shaper TAS and the credit-based shaper CBS mechanism in a single protection window scenario, including:

[0040] Data frames τ of GOOSE traffic and MMS traffic in a single protection window scenario i The total latency inside a TSN switch is:

[0041]

[0042] Among them, L SMV Indicates the length of the protection flow time window used to transmit SMV traffic, L GB Indicates the length of the guard band, L recover Indicates credit recovery time.

[0043] Preferably, the second determination module determines the transmission delay of GOOSE traffic and MMS traffic in a multi-protection window scenario, including:

[0044] Data frames τ of GOOSE traffic and MMS traffic in the multi-protection window scenario i The latency inside a TSN switch is:

[0045]

[0046] in, is the length of the kth protection time window, and m represents the number of times the original TAS time window is divided in a certain transmission.

[0047] Preferably, the third determination module determines the transmission delay of GOOSE traffic and MMS traffic based on the smart substation traffic delay calculation model in a multi-hop network scenario, including:

[0048] In the single protection window scenario, the data frames τ of GOOSE traffic and MMS traffic i The total delay for multi-hop transmission is:

[0049]

[0050] In the multi-protection window scenario, the data frame τ of GOOSE traffic and MMS traffic i The total delay for multi-hop transmission is:

[0051]

[0052] Among them, WCN represents the number of TAS super cycles that data frame transmission needs to wait for, and n is the number of output ports of the TSN switch.

[0053] Beneficial effect: Based on the network structure of the smart substation and the internal structure of the TSN switch, the present invention generates a smart substation traffic delay calculation model, analyzes various scenarios of smart substation traffic transmission, and proposes all the delays that GOOSE traffic and MMS traffic may face under the traffic scheduling combining TAS and CBS mechanisms, as well as the changes of various delays in each scenario. Based on the smart substation traffic delay calculation model, the delay analysis is extended to the scenario of multi-hop network, which can perform accurate delay analysis on the substation traffic transmission process to ensure the transmission performance of critical traffic.

[0054] The features and advantages of the present invention will become clear through reference to the following drawings and detailed description of specific embodiments of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Figure 1 It is a flow chart of a multi-scenario delay analysis method for time-sensitive networks in smart substations;

[0056] Figure 2 This is a schematic diagram of the internal structure of a TSN switch;

[0057] Figure 3 It is a schematic diagram of the division of a single protection window;

[0058] Figure 4 It is a schematic diagram of the division of multiple protection windows;

[0059] Figure 5 This is a schematic diagram of credit value recovery based on the CBS mechanism;

[0060] Figure 6 It is a schematic diagram of the communication network structure of the smart substation simulation experiment;

[0061] Figure 7 It is a schematic diagram of a multi-scenario delay analysis system for time-sensitive networks in smart substations. DETAILED DESCRIPTION

[0062] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0063] Example 1

[0064] Figure 1 This is a flow chart of a multi-scenario delay analysis method for time-sensitive networks in smart substations. Figure 1As shown, this embodiment provides a multi-scenario delay analysis method for a smart substation time-sensitive network, and the method includes the following steps:

[0065] S1: Generate a smart substation traffic delay calculation model based on the network structure of the smart substation and the internal structure of the time-sensitive network TSN switch.

[0066] Specifically, the network structure of the smart substation includes: the smart substation adopts a three-layer two-network structure, the three layers include the station control layer, the interval layer, and the process layer; the two networks include the station control layer network and the process layer network. The station control layer network uses MMS traffic for network communication, and the process layer network uses GOOSE traffic and SMV traffic for network communication. Compared with traditional substations, smart substations are both three-layer two-network structures, but the interval layer and the process layer of traditional substations are connected by cables. In smart substations, the interval layer and the process layer are connected by optical cables, and merging units and intelligent terminals are added under the process layer. The access of optical cables can ensure that the communication of smart substations can be integrated with TSN technology.

[0067] refer to Figure 2 In the communication of smart substations, after the IEC61850 message, which is a general standard in the field of power system automation, enters the TSN switch, it must first pass through the flow filtering and measurement module to limit or block abnormal traffic and complete the corresponding counting operation. There are many feasible implementation plans for the flow filtering operation, such as identifying and discarding duplicate frames and credit-based traffic filtering strategies. Subsequently, the filtered traffic will be assigned the corresponding internal priority according to the message type. According to the pre-set traffic mapping mechanism, all traffic will be divided into protection traffic and non-protection traffic, and will be periodically forwarded to the TAS queue according to the priority according to the circular queuing forwarding CQF mechanism. Subsequently, the time-aware shaper, as the core of TSN technology to ensure the determinism of traffic transmission, will periodically switch the queue gating according to the configured gating list GCL, allowing the data frames in the queue to be transmitted. During the transmission process, the time-sensitive traffic is shaped using the credit-based traffic shaping mechanism or the strict priority-based frame preemption strategy to avoid excessive occupation of bandwidth resources by the same type of messages. In addition, during the entire network transmission process, the IEEE 802.1QAS protocol, as the basis of delay measurable technology, provides global clock synchronization for substation equipment.

[0068] S2: In the single protection window scenario, determine the transmission delay of the general object-oriented substation event GOOSE traffic and the manufacturing message specification MMS traffic after traffic scheduling by combining the time-aware shaper TAS and the credit-based shaper CBS mechanism;

[0069] S3: Determine the transmission delay of GOOSE traffic and MMS traffic in the multi-protection window scenario;

[0070] S4: In a multi-hop network scenario, based on the smart substation traffic delay calculation model, determine the transmission delay of GOOSE traffic and MMS traffic.

[0071] This method can perform accurate time delay analysis on the flow transmission process of the substation and ensure the transmission performance of critical flows.

[0072] Preferably, the smart substation flow delay calculation model includes:

[0073] The data frame τ of GOOSE traffic and MMS traffic i The delay during transmission is expressed as:

[0074] T NPT (τ i )=T FIFO (τ i )+T LP +T HP +T TRANS

[0075]

[0076] Among them, T FIFO (τ i ) represents the data frame τ i The queuing delay caused by the priority queue first-in-first-out strategy, T LP Indicates low priority delay, T HP Indicates high priority delay, T TRANS represents the transmission delay, C i Indicates that the TSN switch transmits data frame τ i The delay generated, C j Indicates that the TSN switch transmits data frame τ j The delay generated, sp(i) represents the delay between the TSN switch and the data frame τ i The set of all frames in the same priority queue, S j represents the credit reduction rate when sending traffic j, I j represents the idle time credit accumulation rate of flow j.

[0077] Specifically, GOOSE traffic and MMS traffic in the substation network are both non-protection traffic. The data frames of GOOSE traffic and MMS traffic will face queuing delay, low priority delay, high priority delay and transmission delay. The data frames of non-protection traffic τ i The worst-case delay during transmission can be formalized as:

[0078] T NPT (τ i )=T FIFO (τ i )+T LP +T HP +T TRANS (1)

[0079] Among them, T FIFO (τ i ) represents the data frame τ i The queuing delay caused by the priority queue first-in-first-out strategy, T LP Indicates low priority delay, T HP Indicates high priority delay, T TRANS Represents the transmission delay, T NPT (τ i ) represents the data frame of the non-protected data flow τ i The worst case delay in the transmission process; T FIFO (τ i ) consists of two parts. The first part is the transmission data frame τ i The delay required by itself, the second part is the transmission and data frame τ i The delay of all other data frames in the same priority queue, and the second part also needs to consider the delay caused by credit value recovery, T FIFO (τ i ) can be formalized as:

[0080]

[0081] In the formula, C i Indicates that the TSN switch transmits data frame τ i The delay generated, C j Indicates that the TSN switch transmits data frame τ j The delay generated, sp(i) represents the delay between the TSN switch and the data frame τ i The set of all frames in the same priority queue, S j represents the credit reduction rate when sending traffic j, I j represents the idle time credit accumulation rate of flow j.

[0082] Preferably, in a single protection window scenario, determining the transmission delay of GOOSE traffic and MMS traffic after traffic scheduling by combining a time-aware shaper TAS and a credit-based shaper CBS mechanism comprises:

[0083] Data frames τ of GOOSE traffic and MMS traffic in a single protection window scenario i The total latency inside a TSN switch is:

[0084]

[0085] Among them, L SMV Indicates the length of the protection flow time window used to transmit SMV traffic, L GB Indicates the length of the guard band, L recover Indicates credit recovery time.

[0086] Specifically, the scheme of setting a single protection window by the TAS mechanism is as follows: Figure 3 As shown in the figure, the entire GCL cycle is divided into three time windows: (1) protection band S0; (2) protection flow time window S1 that can only be used to transmit periodic data frames; (3) non-protection flow time window S2 that can only be used to transmit non-protection type data frames. Therefore, GOOSE traffic and MMS traffic in the substation network can only be transmitted in the non-protection flow time window S2. The TSN standard indicates that when the gate of non-protection traffic is closed, that is, within the protection band S0 and the protection flow time window S1, the credit of this type of traffic can no longer be increased. In addition, if a non-protection traffic frame τ has been started before the protection band is activated i transmission, then τ i Allowing transmission in the guard band, then τ i The credit of the traffic type is reduced within the protection band; the TAS mechanism allows the protection time window to be further divided.

[0087] like Figure 4 As shown, by further dividing Figure 3 The S1 window in the GCL is divided into six time windows: two protection bands S0 and S3, two protection flow time windows S1 and S4, and two non-protection flow time windows S2 and S5. The protection time windows S1 and S4 can be further divided and protection bands can be added accordingly, that is, the traffic scheduling scheme of a single protection window is changed to a multi-protection window scheduling scheme, thereby saving bandwidth.

[0088] The total bandwidth of the non-protected traffic scheduled by the CBS mechanism is equal to the sum of the credit value accumulation rate and the credit value reduction rate of any non-protected type traffic i, that is, I i +S i , then the bandwidth proportion of flow i is The total bandwidth of non-protected traffic is affected by the length of the protection band, the length of the protection flow time window, and the credit recovery time. The total bandwidth ratio of non-protected traffic can be formalized as:

[0089]

[0090] In the formula, BR i Bandwidth allocation ratio of tabular traffic i, I i represents the credit value accumulation rate of flow i, Si Indicates the credit value reduction rate when sending traffic i, L SMV Indicates the length of the protection flow time window used to transmit SMV traffic, L GB Indicates the length of the guard band, L recover Indicates credit recovery time, L TAS Indicates the super period length of the TAS mechanism.

[0091] Furthermore, L recover It can be formalized as:

[0092]

[0093] The credit restoration process Figure 5 As shown in the figure, in the worst case, traffic i is transmitted in the protection band, and the credit value of traffic i is exactly 0 at the beginning of the protection band time slot. Traffic i gets the transmission right and starts to transmit, and the credit value increases at a rate S i The protection time window is decreased, and a data frame is transmitted just at the end of the protection time slot. In the figure, x represents the credit value of flow i at this moment. Then, the credit value of flow i remains unchanged at x in the protection time window. At the end of the protection time window, the queue of flow i contains data frames that have arrived and are ready to be transmitted. The credit value increases at a rate of I i The flow rate i can continue to be transmitted only after it rises to 0. Therefore, we can know that x = C i ×S i And x = L recover ×I i , the two equations can be combined to obtain

[0094] The bandwidth allocation ratio of traffic must also meet certain feasibility conditions. The bandwidth allocation ratio BR for traffic i is i The transmission requirements of flow i should be met, that is, the time required to transmit all frames of flow i should be less than or equal to the bandwidth allocated to flow i. Otherwise, the worst delay of non-protected traffic will be unpredictable, because the traffic may need to be delayed for multiple TAS supercycles before transmission, and the traffic that cannot be transmitted on time will continue to accumulate. The feasibility condition can be formalized as:

[0095]

[0096] If the feasibility condition is met, then in the single protection window scenario, the data frame τ of GOOSE traffic and MMS traffic i The latency inside a TSN switch can be formalized as:

[0097]

[0098] in, represents the internal latency of the TSN switch in a single-window scenario, TNPT (τ i ) is given by formula (1).

[0099] Combining formulas (1), (2), and (6), the data frame τ of GOOSE traffic and MMS traffic in a single protection window scenario is i The overall latency inside a TSN switch is as follows:

[0100]

[0101] This is a relatively conservative upper limit of the delay for a single switch to transmit a data frame, because it assumes that the analyzed data frame needs to wait for the protection band and the protection flow time window, and the current data frame is the last frame in the queue, but it cannot be simply extended to the multi-hop situation. Because the premise of formula (2) is that all data frames in the queue can be transmitted within a TAS super cycle, and multi-hop transmission is performed in the mesh network of the smart substation, the situation will not be so optimistic. The following example will explain the delay calculation method under multi-hop transmission of the smart substation.

[0102] Preferably, in the multi-protection window scenario, determining the transmission delay of GOOSE traffic and MMS traffic includes:

[0103] Data frames τ of GOOSE traffic and MMS traffic in the multi-protection window scenario i The latency inside a TSN switch is:

[0104]

[0105] in, is the length of the kth protection time window, and m represents the number of times the original TAS time window is divided in a certain transmission.

[0106] Specifically, in the smart substation network, assume that a transmission divides the original TAS time window m to 1 times and adds corresponding equal-length protection bands, resulting in m protection bands and m protection time windows. In a TAS supercycle, let the length of the kth protection time window be Then the bandwidth length occupied by the protection window should be changed to The bandwidth occupied by the guard band should be changed to m×L GB , combined with formula (6), under the multi-protection window scenario, the data frame τ of GOOSE traffic and MMS traffic i The latency inside a TSN switch can be formalized as:

[0107]

[0108] The corresponding feasibility conditions also need to change, and the feasibility conditions can be formalized as follows:

[0109]

[0110] in, It represents the bandwidth ratio allocated to traffic i after m-1 window divisions. It can be formalized as:

[0111]

[0112] Among them, L recover Calculated by formula (4).

[0113] Preferably, in a multi-hop network scenario, based on the smart substation traffic delay calculation model, determining the transmission delay of GOOSE traffic and MMS traffic includes:

[0114] In the single protection window scenario, the data frames τ of GOOSE traffic and MMS traffic i The total delay for multi-hop transmission is:

[0115]

[0116] In the multi-protection window scenario, the data frame τ of GOOSE traffic and MMS traffic i The total delay for multi-hop transmission is:

[0117]

[0118] Among them, WCN represents the number of TAS super cycles that data frame transmission needs to wait for, and n is the number of output ports of the TSN switch.

[0119] Specifically, suppose that a non-protected traffic data frame needs to pass through the output ports of n TSN switches to reach the target node without any obstruction on the way. In the most ideal case, the transmission delay is n×T TRANS Each TSN switch inside the smart substation is in a state of multi-stream competition transmission, so the data frames in the priority queue inside a certain TSN switch may come from different nodes and cannot be transmitted uninterruptedly according to the transmission order in the previous hop switch. FIFO (τ i ) in which sp(i) should include all frames with the same priority in the network. The delay caused by low-priority and high-priority data frames will increase to n×T respectively. LP and n×T HPThe delay caused by the TAS mechanism in the smart substation network depends on the number of TAS super cycles that need to be waited, that is, after the data frame of the non-protected traffic arrives at the output port of the TSN switch, it needs to wait for multiple TAS super cycles before it can be transmitted. The traffic blocking the current frame transmission includes all traffic with the same priority, low priority and high priority. Since the worst-case non-protected traffic delay needs to be obtained and the transmitted data frame itself is not considered, and because the number of TAS super cycles that need to be waited should be an integer, the result needs to be rounded up. The number of TAS super cycles that need to be waited for data frame transmission can be formalized as:

[0120]

[0121] Where WCN represents the number of TAS supercycles that data frame transmission needs to wait for, L NPT Indicates the length of the non-protected window.

[0122] Combining all the above delays, the data frame τ in a single window scenario i The total delay for multi-hop transmission can be formalized as:

[0123]

[0124] Formula (12) is the theoretical upper limit of the worst-case delay of all non-protection flows in the smart substation. Since GOOSE flows are usually regarded as the highest priority flows, the high priority delay T of GOOSE flows is HP It can be ignored. In addition, low-priority blocking does not necessarily occur in multi-hop networks. We can further refine the worst-case delay of various types of non-protected traffic to make the delay results of GOOSE traffic more accurate.

[0125] In a multi-hop smart substation network, the opening time of the TAS non-protection time window of the TSN switch output port, that is, the end time of the protection window, is set according to the opening time of the window of the previous hop and the transmission time of the SMV traffic. For example, let the opening time of the TAS non-protection time window of the output port of TSN switch j be t, and the delay of transmitting an SMV traffic data frame be constant as T SMV , then the opening time of the TAS non-protection time window of the output port of the next-hop TSN switch j+1 should be set to t+T SMV , the first data frame τ of the highest priority GOOSE traffic GOOSE The transmission can be obtained at the opening time of the non-protection time window of TSN switch j and sent to switch j+1, and switch j+1 transmits τ GOOSE There are two situations at this moment:

[0126] Case (1): Transmitting GOOSE data frame τ GOOSE The delay TGOOSE Greater than the delay T required to transmit an SMV traffic data frame SMV , then the data frame τ i When it reaches switch j+1, the non-protection time window has been opened. In this case, the data frame τ GOOSE There is a possibility that transmission may be blocked by low-priority traffic, so the worst-case delay of GOOSE traffic should be calculated according to formula (12).

[0127] Case (2): Transmitting GOOSE data frame τ GOOSE The delay T GOOSE Less than or equal to the delay T required to transmit an SMV traffic data frame SMV , then the data frame τ GOOSE When it reaches switch j+1, the non-protection time window has not yet been opened or has just been opened, so the first frame after the non-protection time window is opened will transmit the data frame τ i , in this case the data frame τ i The transmission delay of the low-priority traffic can only be generated at the first TSN switch at most, that is, the low-priority delay will be generated from n×T LP Downgrade to T LP The resulting transmission latency within a TSN switch should be T SMV -T GOOSE , in a multi-hop network, it should be n×(T SMV -T GOOSE ). In addition, removing the high priority delay, the multi-hop transmission delay of GOOSE traffic in this case can be formalized as:

[0128]

[0129] In the formula, C GOOSE Indicates that the TSN switch transmits data frame τ GOOSE The delay generated, sp(GOOSE) represents the delay between the TSN switch and the data frame τ GOOSE The set of all frames in the same priority queue.

[0130] The priority of MMS traffic is not as high as that of GOOSE traffic. During the transmission process, it not only needs to face the delay caused by low priority traffic, but also needs to consider the delay caused by high priority traffic. Even if the arrival of MMS traffic is relatively ideal as in the above situation (2), after transmitting a data frame, if there is GOOSE traffic that has already arrived in the queue, GOOSE traffic will still compete for the transmission right. The number of frames that MMS traffic needs to wait depends on the idleslope and sendslope of GOOSE traffic.

[0131] Assume that the idleslope and sendslope of GOOSE traffic are IGOOSE and S GOOSE , the maximum time required for the transmission of GOOSE traffic is This is the time when the GOOSE data frame leaves the switch output port, which is different from the previous T GOOSE , the maximum time required to transmit a data frame in the substation network is C MAX In the worst case, GOOSE traffic starts to be transmitted after waiting for the largest data frame in a network to be transmitted. The credit value of GOOSE traffic starts to decrease after transmission. After a certain time, the credit value is reduced to 0. At this moment, if the current GOOSE traffic data frame has just completed transmission, it can still continue to transmit a frame. Therefore, the waiting time in a TSN switch caused by high-priority traffic should be Right now In a multi-hop network,

[0132] The multi-hop transmission delay of MMS traffic can be formalized as:

[0133]

[0134] Among them, C MMS Indicates that the TSN switch transmits data frame τ MMS The delay generated, sp(MMS) represents the delay between the TSN switch and the data frame τ MMS The set of all frames in the same priority queue.

[0135] Furthermore, in the multi-protection window scenario, the data frame τ of GOOSE traffic and MMS traffic i The total delay for multi-hop transmission can be formalized as:

[0136]

[0137] This embodiment generates a smart substation traffic delay calculation model based on the network structure of the smart substation and the internal structure of the TSN switch, analyzes various scenarios of smart substation traffic transmission, and proposes all the delays that GOOSE traffic and MMS traffic may face under traffic scheduling combining TAS and CBS mechanisms, as well as the changes in various delays in each scenario. Based on the smart substation traffic delay calculation model, the delay analysis is extended to the multi-hop network scenario, which can accurately analyze the delay of the substation traffic transmission process and ensure the transmission performance of critical traffic.

[0138] by Figure 6 Taking the substation network shown as an example, the accuracy of the multi-scenario delay analysis of GOOSE traffic and MMS traffic proposed in this embodiment is verified by comparing it with the actual network transmission delay. Figure 6 In the figure, MU1 to MU18 represent 18 merging units, which are divided into four parts to send SMV traffic, GOOSE traffic, MMS traffic and BE traffic respectively. Each data frame is generated by the merging unit and sent to the substation process layer switch through the regional switch. After three-hop transmission, it is finally sent to the designated terminal equipment EP1 to EP3 for data analysis.

[0139] According to the unified communication standard IEC 61850 protocol within the substation, the frame length of time-sensitive traffic does not exceed 354 bytes. Considering the low latency requirement of SMV traffic, SMV is sent at a time interval of 100μs as protection traffic. Other IEC 61850 traffic is sent at 0μs to simulate the worst case of network transmission. BE traffic is sent in an exponential distribution with a rate parameter of λ=0.1. All links in the substation network are full-duplex with a total bandwidth of 100Mbps.

[0140] For GOOSE traffic, the worst-case delay of GOOSE traffic in a single window is calculated to be 0.281ms, the actual maximum delay of the device ranges from 0.241ms to 0.280ms, the average maximum delay is 0.261ms, and the worst-case delay deviates from the calculated value by 0.35%. The worst-case delay of GOOSE traffic in multiple windows is 0.175ms, the actual maximum delay of the device ranges from 0.135ms to 0.162ms, the average maximum delay is 0.149ms, and the worst-case delay deviates from the calculated value by 7.43%. Dividing the TAS mechanism of a single protection time window into multiple protection windows has a higher optimization percentage for the worst-case delay of GOOSE traffic. This is because the extra bandwidth will transmit GOOSE traffic in advance, and the transmission of MMS traffic and BE traffic will also be blocked when the network transmission is congested.

[0141] For MMS traffic, the worst-case latency of MMS traffic in a single window is 33.667ms, the actual maximum latency of the device ranges from 3.578ms to 32.660ms, the average maximum latency is 15.991ms, and the worst-case latency deviates from the calculated value by 2.99%. The worst-case latency of MMS traffic in multiple windows is 28.026ms, the actual maximum latency of the device ranges from 3.578ms to 26.323ms, the average maximum latency is 13.323ms, and the worst-case latency deviates from the calculated value by 6.08%.

[0142] Example 2

[0143] Figure 7 This is a schematic diagram of a multi-scenario delay analysis system for time-sensitive networks in smart substations. Figure 7 As shown, this embodiment provides a multi-scenario delay analysis system for a time-sensitive network of a smart substation, the system comprising:

[0144] The model generation module 701 is used to generate a smart substation traffic delay calculation model according to the network structure of the smart substation and the internal structure of the time sensitive network TSN switch;

[0145] The first determination module 702 is used to determine the transmission delay of the substation event GOOSE traffic and the manufacturing message specification MMS traffic oriented to the general object after the traffic scheduling combined with the time-aware shaper TAS and the credit-based shaper CBS mechanism in the single protection window scenario;

[0146] The second determination module 703 is used to determine the transmission delay of GOOSE traffic and MMS traffic in a multi-protection window scenario;

[0147] The third determination module 704 is used to determine the transmission delay of GOOSE traffic and MMS traffic based on the smart substation traffic delay calculation model in a multi-hop network scenario.

[0148] Preferably, the model generation module 701 generates a smart substation flow delay calculation model including:

[0149] The data frame τ of GOOSE traffic and MMS traffic i The delay during transmission is expressed as:

[0150] T NPT (τ i )=T FIFO (τ i )+T LP +T HP +T TRANS

[0151]

[0152] Among them, T FIFO (τ i ) represents the data frame τ i The queuing delay caused by the priority queue first-in-first-out strategy, T LP Indicates low priority delay, T HP Indicates high priority delay, T TRANS represents the transmission delay, C i Indicates that the TSN switch transmits data frame τ i The delay generated, C j Indicates that the TSN switch transmits data frame τ j The delay generated, sp(i) represents the delay between the TSN switch and the data frame τ i The set of all frames in the same priority queue, S j represents the credit reduction rate when sending traffic j, Ij represents the idle time credit accumulation rate of flow j.

[0153] Preferably, the first determination module 702 determines the transmission delay of GOOSE traffic and MMS traffic after traffic scheduling by combining the time-aware shaper TAS and the credit-based shaper CBS mechanism in a single protection window scenario, including:

[0154] Data frames τ of GOOSE traffic and MMS traffic in a single protection window scenario i The total latency inside a TSN switch is:

[0155]

[0156] Among them, L SMV Indicates the length of the protection flow time window used to transmit SMV traffic, L GB Indicates the length of the guard band, L recover Indicates credit recovery time.

[0157] Preferably, the second determining module 703 determines the transmission delay of GOOSE traffic and MMS traffic in a multi-protection window scenario, including:

[0158] Data frames τ of GOOSE traffic and MMS traffic in the multi-protection window scenario i The latency inside a TSN switch is:

[0159]

[0160] in, is the length of the kth protection time window, and m represents the number of times the original TAS time window is divided in a certain transmission.

[0161] Preferably, the third determination module 704 determines the transmission delay of GOOSE traffic and MMS traffic based on the smart substation traffic delay calculation model in a multi-hop network scenario, including:

[0162] In the single protection window scenario, the data frames τ of GOOSE traffic and MMS traffic i The total delay for multi-hop transmission is:

[0163]

[0164] In the multi-protection window scenario, the data frame τ of GOOSE traffic and MMS traffic i The total delay for multi-hop transmission is:

[0165]

[0166] Among them, WCN represents the number of TAS super cycles that data frame transmission needs to wait for, and n is the number of output ports of the TSN switch.

[0167] The specific implementation process of the functions realized by each module in this embodiment 2 is the same as the implementation process in embodiment 1, and will not be repeated here.

[0168] The above description is only a preferred embodiment of the present invention, and does not limit the patent scope of the present invention. All equivalent structural changes made by using the contents of the present invention specification and drawings under the concept of the present invention, or directly / indirectly applied in other related technical fields are included in the patent protection scope of the present invention.

Claims

1. A multi-scenario delay analysis method for a time-sensitive network of a smart substation, characterized in that: The method comprises the following steps: According to the network structure of the smart substation and the internal structure of the time-sensitive network TSN switch, a smart substation traffic delay calculation model is generated; In the single protection window scenario, the transmission delay of the general object-oriented substation event GOOSE traffic and the manufacturing message specification MMS traffic after traffic scheduling by combining the time-aware shaper TAS and the credit-based shaper CBS mechanism is determined; Determine the transmission delay of GOOSE traffic and MMS traffic in the multi-protection window scenario; In a multi-hop network scenario, based on the smart substation traffic delay calculation model, the transmission delay of GOOSE traffic and MMS traffic is determined; The smart substation flow delay calculation model includes: The data frames of GOOSE traffic and MMS traffic The delay during transmission is expressed as: ， ， in, Represents a data frame The queuing delay caused by the priority queue first-in-first-out strategy, Indicates low priority delay, Indicates high priority delay, Indicates the transmission delay, Indicates that the TSN switch transmits data frames The delay generated, Indicates that the TSN switch transmits data frames The delay generated, Indicates the data frame in the TSN switch The set of all frames in the same priority queue, Indicates flow rate The credit reduction rate when sending, Indicates flow rate The idle time credit accumulation rate.

2. The method according to claim 1, characterized in that The method of determining the transmission delay of GOOSE traffic and MMS traffic after traffic scheduling by combining the time-aware shaper TAS and the credit-based shaper CBS mechanism in a single protection window scenario includes: Data frames of GOOSE traffic and MMS traffic in a single protection window scenario The total latency inside a TSN switch is: , in, Indicates the length of the protection flow time window used to transmit SMV traffic. Indicates the length of the guard band, Indicates credit recovery time.

3. The method according to claim 2, characterized in that In the multi-protection window scenario, determining the transmission delay of GOOSE traffic and MMS traffic includes: Data frames of GOOSE traffic and MMS traffic in the multi-protection window scenario The latency inside a TSN switch is: ， in, For the The length of a protection time window, m represents the number of times the original TAS time window is divided for a certain transmission.

4. The method according to claim 3, characterized in that In the multi-hop network scenario, based on the smart substation traffic delay calculation model, determining the transmission delay of GOOSE traffic and MMS traffic includes: Data frames of GOOSE traffic and MMS traffic in a single protection window scenario The total delay for multi-hop transmission is: ， Data frames of GOOSE traffic and MMS traffic in a multi-protection window scenario The total delay for multi-hop transmission is: ， in, It indicates the number of TAS super cycles that data frame transmission needs to wait for, and n is the number of output ports of the TSN switch.

5. A multi-scenario delay analysis system for time-sensitive networks in smart substations, characterized in that: The system comprises: A model generation module is used to generate a smart substation traffic delay calculation model based on the network structure of the smart substation and the internal structure of the time-sensitive network TSN switch; The first determination module is used to determine the transmission delay of the substation event GOOSE flow and the manufacturing message specification MMS flow oriented to the general object after the flow scheduling combined with the time-aware shaper TAS and the credit-based shaper CBS mechanism in the single protection window scenario; The second determination module is used to determine the transmission delay of GOOSE traffic and MMS traffic in a multi-protection window scenario; The third determination module is used to determine the transmission delay of GOOSE traffic and MMS traffic based on the smart substation traffic delay calculation model in a multi-hop network scenario. The model generation module generates a smart substation flow delay calculation model including: The data frames of GOOSE traffic and MMS traffic The delay during transmission is expressed as: ， ， in, Represents a data frame The queuing delay caused by the priority queue first-in-first-out strategy, Indicates low priority delay, Indicates high priority delay, Indicates the transmission delay, Indicates that the TSN switch transmits data frames The delay generated, Indicates that the TSN switch transmits data frames The delay generated, Indicates the data frame in the TSN switch The set of all frames in the same priority queue, Indicates flow rate The credit reduction rate when sending, Indicates flow rate The idle time credit accumulation rate.

6. The system according to claim 5, characterized in that The first determination module determines the transmission delay of GOOSE traffic and MMS traffic after traffic scheduling by combining the time-aware shaper TAS and the credit-based shaper CBS mechanism in a single protection window scenario, including: Data frames of GOOSE traffic and MMS traffic in a single protection window scenario The total latency inside a TSN switch is: , in, Indicates the length of the protection flow time window used to transmit SMV traffic. Indicates the length of the guard band, Indicates credit recovery time.

7. The system according to claim 6, characterized in that The second determination module determines the transmission delay of GOOSE traffic and MMS traffic in a multi-protection window scenario, including: Data frames of GOOSE traffic and MMS traffic in the multi-protection window scenario The latency inside a TSN switch is: ， in, For the The length of a protection time window, m represents the number of times the original TAS time window is divided for a certain transmission.

8. The system according to claim 7, characterized in that The third determination module determines the transmission delay of GOOSE traffic and MMS traffic based on the smart substation traffic delay calculation model in a multi-hop network scenario, including: Data frames of GOOSE traffic and MMS traffic in a single protection window scenario The total delay for multi-hop transmission is: ， Data frames of GOOSE traffic and MMS traffic in a multi-protection window scenario The total delay for multi-hop transmission is: ， in, It indicates the number of TAS super cycles that data frame transmission needs to wait for, and n is the number of output ports of the TSN switch.

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