A power distribution network protection control device GOOSE message transmission method

Abstract

The application discloses a GOOSE message transmission method of a power distribution network protection control device, which comprises a compression process and a decompression process of the GOOSE message. In the compression process, different coding states are entered according to different message states, the transmission resource consumption of the same data is significantly reduced, and the compression ratio of the message is improved. The decompression process comprises two aspects of compression type detection discrimination and decoding of the received message. The application ensures efficient and stable transmission of fault messages, improves the reliability of the system, effectively saves resources under the condition of limited channel bandwidth, ensures the integrity, reliability and real-time performance of data transmission, greatly improves the transmission efficiency of the message, and enhances the real-time processing and application effect of the message.

Description

Technical Field

[0001] This invention pertains to power message data processing technology, specifically relating to a method for transmitting GOOSE (Generic ObjectOriented Substation Event) messages. Background Technology

[0002] Smart distribution networks, utilizing 5G communication networks, with their "three highs and two lows" characteristics (high speed, high capacity, high reliability, low latency, and low energy consumption), meet the transmission requirements of distribution network protection and control services, and are gradually becoming a hot topic in this field of research and application. However, in actual operation, the data volume of distribution network protection and control services is extremely large, and direct transmission through 5G networks will significantly increase operating costs and resource consumption. Therefore, effective compression is particularly necessary before data transmission.

[0003] Currently, distribution network protection and control services primarily rely on the GOOSE message protocol for data transmission. Under non-fault conditions, the protection device periodically sends heartbeat messages at T0 time intervals and retransmits them during T0 at intervals of "T1-T1-T2-T3". Due to the significant correlation between heartbeat messages, data compression technology can effectively reduce the amount of data that needs to be transmitted. However, under fault conditions, the protection device sends fault messages at time intervals much shorter than T0. To ensure the accuracy of fault message transmission, transparent transmission is considered. However, the aforementioned message compression process relies on a fast fault detection mechanism.

[0004] Furthermore, in power distribution networks, GOOSE messages are typically transmitted via multicast, meaning each sending device can send messages to multiple devices, and each device can receive messages from multiple other devices. Therefore, it is necessary to design the message structure and frame format of the compressed messages to ensure they can be effectively received. Summary of the Invention

[0005] Purpose of the invention: In view of the above-mentioned prior art, a GOOSE message transmission method for distribution network protection and control devices is proposed. Through the encoding and compression mechanism, the resource consumption of the same data can be significantly reduced before transmission, while ensuring the integrity, reliability and real-time performance of data transmission.

[0006] Technical Solution: A method for transmitting GOOSE messages in a distribution network protection and control device, wherein the GOOSE messages are transmitted between distributed distribution protection self-healing devices, and the messages to be sent are sequentially assigned to different sequences according to the Destination Mac and APPID parameters in the GOOSE message; for any sequence, the method includes the following steps:

[0007] S01: Initialization: Clear the counter cnt to zero and set the I-frame repeat period value to N;

[0008] S02: Initial state: Read one frame of message sequentially, send the message directly without compression or encoding, and calculate Δst. n Δsq n According to Δst n-1 Δsq n-1 Δst n Δsq n If the conditions for entering the encoding waiting state are met, proceed to step S03; otherwise, repeat this step until no more messages to be sent are read.

[0009] S03: Enter the encoding waiting state, continue reading 1 frame of the message in sequence, and calculate Δst. n Δsq n According to Δst n-1 Δsq n-1 Δst n Δsq n If the conditions for entering the fault state are met, the current frame message is sent directly without compression encoding, and then proceed to step S04; if the conditions for entering the encoding state are met, then according to Δst... n-1 Δsq n-1 Δst n Δsq n If the combination of conditions is not met, the current frame message is compressed and encoded and sent, and then the process proceeds to step S05; if none of the conditions are met, the current frame message is sent directly without compression and encoding, and this step is repeated until no more messages to be sent are read.

[0010] S04: Entering fault state, continue reading 1 frame of message in sequence, send the current frame of message directly without compression encoding, and calculate Δst. n Δsq n According to Δst n-1 Δsq n-1 Δst n Δsq n If the conditions for exiting the fault state are met, the counter cnt is cleared and the process proceeds to step S03; otherwise, this step is repeated until no more messages to be sent are read.

[0011] S05: Enter encoding state, continue reading 1 frame of message sequentially, and calculate Δst. n Δsq n According to Δst n-1 Δsq n-1 Δst n Δsq nIf the conditions for entering a fault state are met, the current frame message is sent directly without compression encoding, and then proceed to step S04; otherwise, based on Δst... n-1 Δsq n-1 Δst n Δsq n The current frame message is compressed and encoded based on the combination of different conditions and then sent. This process is repeated until no more messages to be sent are read.

[0012] For the nth frame message, Δst n = stNum n -stNum n-1 ,Δsq n = sqNum n -sqNum n-1 stNum n sqNum n These represent the stNum and sqNum parameters in the nth frame, where n ≥ 3; Δst is set when the first frame is read. n =Δst n-1 =0, Δsq n =Δsq n-1 =0, when the second frame of the message is read, Δst n-1 =0, Δsq n-1 =0.

[0013] Furthermore, in step S02, the condition for entering the encoding waiting state is: Δst n-1 =0, Δsq n-1 =1, Δst n =0, Δsq n =1;

[0014] In steps S03 and S05, the condition for entering the fault state is any one of the following five conditions:

[0015] Δst n-1 =1, Δsq n-1 =0, Δst n =1, Δsq n =0;

[0016] Δst n-1 =1, Δsq n-1 =-2, Δst n =1, Δsq n =0;

[0017] Δst n-1 =1, Δsq n-1 =-1, Δst n =1, Δsqn =0;

[0018] Δst n-1 =1, Δsq n-1 =-3, Δst n =1, Δsq n =0;

[0019] Δst n-1 =1, Δsq n-1 =-4, Δst n =1, Δsq n =0;

[0020] In step S03, the condition for entering the encoding state is: Δst n-1 =0, Δsq n-1 =1, Δst n =1, Δsq n =-4;

[0021] In step S04, the condition for exiting the fault state is: Δst n-1 =1, Δsq n-1 =0, Δst n =0, Δsq n =1.

[0022] Furthermore, in steps S03 and S05, according to Δst n-1 Δsq n-1 Δst n Δsq n The steps for compressing and encoding messages based on combinations of data include:

[0023] S001: Based on the current frame message, if Δst n-1 =0, Δsq n-1 =1, Δst n =1, Δsq n If the value is -4, then the counter cnt is incremented by 1, and then the process proceeds to step S002; otherwise, the process proceeds directly to step S002.

[0024] S002: Determine the value of counter cnt. If the value of counter cnt is equal to (N+1), set counter cnt=1 and proceed to step S003. Otherwise, proceed directly to step S003.

[0025] S003: If Δst at this time n-1 =0, Δsq n-1 =1, Δst n =1, Δsq nIf the value is -4, then the current frame is defined as an I-frame and buffered. The PDU data of the I-frame message is encoded using a lossless encoding method, and the parameter values ​​of the IEC-GOOSE part in the message frame structure are modified. Otherwise, the current frame is defined as a P-frame. The residual between the PDU data of the P-frame message and the PDU data of the buffered I-frame message is calculated. The residual data is encoded using a lossless encoding method. The PDU data of the P-frame message is replaced with the encoded residual data, and the parameter values ​​of the IEC-GOOSE part in the message frame structure are modified.

[0026] Furthermore, in the compressed and encoded GOOSE message frame structure, the IEC-GOOSE part includes an "I / P frame tag" field and an "I frame feature tag" field, wherein the "I frame feature tag" field is the stNum of the currently cached I frame message.

[0027] Furthermore, the receiver, based on the APPID parameter in the message frame, categorizes the received GOOSE messages into different decoding sequences for processing; for any given sequence, the decompression process includes:

[0028] S11: Read one frame of message in sequence. Based on the "I / P frame marker" parameter in the message, if it is an uncompressed message, it is directly transmitted to the distributed power distribution protection self-healing device, and then proceed to step S15; if it is an I frame message, proceed to step S12; if it is a P frame message, proceed to step S13.

[0029] S12: For the PDU data in the I-frame message, use the inverse algorithm that matches the PDU data compression algorithm of the I-frame message to decode it, cache the I-frame message, and then set the "I / P frame mark" and "I frame feature mark" parameters of the IEC-GOOSE part in the frame structure of the I-frame message to 0. After that, transmit the message to the next unit of the distributed power distribution protection self-healing device and proceed to step S15.

[0030] S13: Determine if there is a buffered I-frame packet. If not, discard the P-frame packet and proceed to step S15. If there is, proceed to step S14.

[0031] S14: Compare the "I-frame feature marker" in the current P-frame message with the "I-frame feature marker" in the cached I-frame message. If they are different, discard the received P-frame message and proceed to step S15. If they are the same, decode the PDU data in the current P-frame message using an inverse algorithm that matches the PDU residual data compression algorithm of the P-frame message to obtain the residual between the cached I-frame message PDU data and the P-frame PDU data. Then, recover the original P-frame PDU data based on the cached I-frame message PDU data. Set both the "I / P-frame marker" and "I-frame feature marker" parameters to 0, then transmit the message to the next unit of the distributed power distribution protection self-healing device and proceed to step S15.

[0032] S15: Continue reading the next frame of the message in the sequence. If there is one, proceed to step S11; otherwise, end the decoding.

[0033] Furthermore, a compression and transmission module is configured to perform steps S01 to S05, the compression and transmission module being connected to at least one distributed power distribution protection self-healing device; and a receiving and decompression module is configured to perform steps S11 to S15, the receiving and decompression module being connected to at least one distributed power distribution protection self-healing device.

[0034] Furthermore, the receiving and decompression module receives the GOOSE message, compares the Destination MAC parameter in the message, and determines whether it is a message sent to the distributed power distribution protection self-healing device connected to it. If not, the message is discarded.

[0035] Furthermore, the lossless encoding method includes Huffman coding and run-length coding.

[0036] Furthermore, in the GOOSE message frame structure, the "I / P frame flag" is defined as 0000H when the message is not compressed, 0001H in I frames, and 0010H in P frames.

[0037] Beneficial effects: 1) The method of the present invention effectively removes redundant information between similar messages by reusing the same information in consecutive message data, thereby significantly improving the message compression ratio.

[0038] 2) Fault Detection Mechanism Design: For the GOOSE message transmission mechanism, this invention designs an efficient message fault detection mechanism by identifying the stNum and sqNum parameters in the message. This mechanism ensures efficient and stable transmission of faulty messages, improving system reliability.

[0039] 3) Frame loss and frame order discrimination mechanism: In order to solve the problems of frame loss and frame order reception errors that may occur in wireless transmission, this method designs a corresponding discrimination mechanism in the decoding process, which effectively reduces the impact of transmission errors on message decoding, thereby ensuring data integrity.

[0040] 4) Residual simplification and encoding: By calculating the residual between the P-frame and the I-frame and encoding these residuals, the transmission of the same data can be effectively reduced, further improving the compression efficiency.

[0041] 5) Resource Consumption and Transmission Efficiency Optimization: The method of this invention significantly reduces the resource consumption for transmitting the same data and improves the compression ratio of the messages. When channel bandwidth is limited, this method can effectively save resources, ensure the integrity, reliability, and real-time performance of data transmission, greatly improve message transmission efficiency, and enhance the real-time processing and application effects of messages. Attached Figure Description

[0042] Figure 1 This is a compression state diagram in the present invention;

[0043] Figure 2 This is a flowchart of the decompression process of the method of the present invention;

[0044] Figure 3 It is the original GOOSE message frame format;

[0045] Figure 4 This is the compressed message format. Detailed Implementation

[0046] The invention will now be further explained with reference to the accompanying drawings.

[0047] This embodiment uses the GOOSE message as an example to illustrate the encoding process of the GOOSE message. This protocol belongs to the GOOSE message described in this invention, and the protocol frame format is as follows:

[0048]

[0049] The information represented by each field is as follows:

[0050] Destination MAC address

[0051] Source MAC address

[0052] Ethernet Type — Ethernet type value

[0053] TPID - Optional Field

[0054] TCI - Optional Field

[0055] APPID - Application Identifier

[0056] App Length — Length field

[0057] Reserved1 — Reserved bit 1

[0058] Reserved1——Reserved bit 2

[0059] PDU – Protocol Data Unit

[0060] stNUM — State number, used to record the total number of times GOOSE data has changed.

[0061] sqNUM — Sequence number, used to record the number of frames sent in steady-state conditions.

[0062] A method for transmitting GOOSE messages in a distribution network protection and control device is disclosed. GOOSE messages are transmitted between distributed distribution protection self-healing devices. The system is configured with a compression and transmission module connected to at least one distributed distribution protection self-healing device. The compression and transmission module receives GOOSE messages sent by the connected distributed distribution protection self-healing devices and, based on the Destination Mac and APPID parameters in the GOOSE message, sequentially categorizes the messages to be transmitted into different sequences. For any sequence, the method includes the following steps:

[0063] S01: Initialization: Clear the counter cnt to zero and set the I-frame repetition period to N. The I-frame repetition period N means that an I-frame is set every N "heartbeat frames". In principle, N should be greater than or equal to 1. In actual engineering, the value of N is set according to the compression ratio requirements.

[0064] S02: Initial state: Read one frame of message sequentially, send the message directly without compression or encoding, and calculate Δst. n Δsq n According to Δst n-1 Δsq n-1 Δst n Δsq n If the conditions for entering the encoding waiting state are met, proceed to step S03; otherwise, repeat this step until no more messages to be sent are read.

[0065] S03: Enter the encoding waiting state, continue reading 1 frame of the message in sequence, and calculate Δst. n Δsq n According to Δst n-1 Δsq n-1 Δst n Δsq nIf the conditions for entering the fault state are met, the current frame message is sent directly without compression encoding, and then proceed to step S04; if the conditions for entering the encoding state are met, then according to Δst... n-1 Δsq n-1 Δst n Δsq n If the combination of conditions is not met, the message is compressed and encoded and sent, and then the process proceeds to step S05; if none of the conditions are met, the current frame message is sent directly without compression and encoding, and this step is repeated until no more messages to be sent are read.

[0066] S04: Entering fault state, continue reading 1 frame of message in sequence, send the current frame of message directly without compression encoding, and calculate Δst. n Δsq n According to Δst n-1 Δsq n-1 Δst n Δsq n If the conditions for exiting the fault state are met, the counter cnt is cleared and the process proceeds to step S03; otherwise, this step is repeated until no more messages to be sent are read.

[0067] S05: Enter encoding state, continue reading 1 frame of message sequentially, and calculate Δst. n Δsq n According to Δst n-1 Δsq n-1 Δst n Δsq n If the conditions for entering a fault state are met, the current frame message is sent directly without compression encoding, and then proceed to step S04; otherwise, based on Δst... n-1 Δsq n-1 Δst n Δsq n The message is compressed and encoded according to the combination of conditions and then sent. This step is repeated until no more messages to be sent are read.

[0068] For the nth frame message, Δst n = stNum n -stNum n-1 ,Δsq n = sqNum n -sqNum n-1 stNum n sqNum n These represent the stNum and sqNum parameters in the nth frame, where n ≥ 3; Δst is set when the first frame is read. n =Δst n-1=0, Δsq n =Δsq n-1 =0, when the second frame of the message is read, Δst n-1 =0, Δsq n-1 =0.

[0069] In step S02, the condition for entering the encoding waiting state is: Δst n-1 =0, Δsq n-1 =1, Δst n =0, Δsq n =1.

[0070] In steps S03 and S05, the condition for entering the fault state is any one of the following five conditions:

[0071] Δst n-1 =1, Δsq n-1 =0, Δst n =1, Δsq n =0;

[0072] Δst n-1 =1, Δsq n-1 =-2, Δst n =1, Δsq n =0;

[0073] Δst n-1 =1, Δsq n-1 =-1, Δst n =1, Δsq n =0;

[0074] Δst n-1 =1, Δsq n-1 =-3, Δst n =1, Δsq n =0;

[0075] Δst n-1 =1, Δsq n-1 =-4, Δst n =1, Δsq n =0;

[0076] In step S03, the condition for entering the encoding state is: Δst n-1 =0, Δsq n-1 =1, Δst n =1, Δsq n =-4.

[0077] In step S04, the condition for exiting the fault state is: Δst n-1 =1, Δsqn-1 =0, Δst n =0, Δsq n =1.

[0078] In steps S03 and S05, according to Δst n-1 Δsq n-1 Δst n Δsq n The steps for compressing and encoding messages based on combinations of data include:

[0079] S001: Based on the current frame message, if Δst n-1 =0, Δsq n-1 =1, Δst n =1, Δsq n If the value is -4, then the counter cnt is incremented by 1 and the process proceeds to step S002; otherwise, the process proceeds directly to step S002.

[0080] S002: Determine the value of counter cnt. If the value of counter cnt is equal to (N+1), set counter cnt=1 and proceed to step S003. Otherwise, proceed directly to step S003.

[0081] S003: If Δst at this time n-1 =0, Δsq n-1 =1, Δst n =1, Δsq n If the value is -4, the current frame is defined as an I-frame and buffered. The PDU data of this I-frame message is encoded using lossless encoding methods such as Huffman coding and run-length encoding. Simultaneously, the parameter values ​​of the IEC-GOOSE part in the message frame structure are modified. Otherwise, the current frame is defined as a P-frame. The residual between the PDU data of this P-frame message and the PDU data of the buffered I-frame message is calculated. The residual data is encoded using lossless encoding methods such as Huffman coding and run-length encoding. The PDU data of this P-frame message is replaced with the encoded residual data. Simultaneously, the parameter values ​​of the IEC-GOOSE part in the message frame structure are modified. In the compressed GOOSE message frame structure, the IEC-GOOSE part includes an "I / P frame tag" byte and an "I-frame feature tag" field. The "I-frame feature tag" field is the stNum of the currently buffered I-frame message. In the GOOSE message frame structure, the "I / P frame flag" is defined as 0000H when the message is not compressed, 0001H in I frames, and 0010H in P frames.

[0082] The structure of the compressed GOOSE message frame is as follows:

[0083]

[0084] The parameter values ​​are defined as follows: Length = 8 + n; "I / P frame flag" is 0000H (hexadecimal) when the message is not compressed, 0001H for I-frames, and 0010H for P-frames; "I-frame feature flag" is the stNum of the currently buffered I-frame message; the remaining parameters retain the original data values.

[0085] The system is configured with a receiving and decompression module, which is connected to at least one distributed distribution protection self-healing device. Upon receiving a GOOSE message, the receiving and decompression module first compares the Destination MAC parameter in the message to determine if it is a message sent to a connected distributed distribution protection self-healing device; if not, the message is discarded. Then, based on the APPID parameter in the message frame, the receiving and decompression module categorizes the received GOOSE messages into different decoding sequences for processing. For any sequence, the decompression process includes:

[0086] S11: Read one frame message in sequence. Based on the "I / P frame marker" parameter in the message, if it is an uncompressed message, it is directly transmitted to the next unit of the distributed power distribution protection self-healing device, and then proceed to step S15; if it is an I frame message, proceed to step S12; if it is a P frame message, proceed to step S13.

[0087] S12: For the PDU data in the I-frame message, use the inverse algorithm that matches the PDU data compression algorithm of the I-frame message to decode it. Assume that the length of the decoded data is m bytes. Set the Length parameter of the IEC-GOOSE part in the I-frame message frame structure to 8+m. Buffer the I-frame message. Then set the "I / P frame mark" and "I frame feature mark" parameters of the IEC-GOOSE part in the I-frame message frame structure to 0. After that, transmit the message to the next unit of the distributed power distribution protection self-healing device and proceed to step S15.

[0088] S13: Determine if there is a buffered I-frame packet. If not, discard the P-frame packet and proceed to step S15. If there is, proceed to step S14.

[0089] S14: Compare the "I-frame feature marker" in the current P-frame message with the "I-frame feature marker" in the cached I-frame message. If they are different, discard the received P-frame message and proceed to step S15. If they are the same, decode the PDU data in the current P-frame message using an inverse algorithm that matches the PDU residual data compression algorithm of the P-frame message to obtain the residual between the cached I-frame message PDU data and the P-frame PDU data. Then, recover the original P-frame PDU data based on the cached I-frame message PDU data. Assuming the length of the recovered original P-frame PDU data is m bytes, set the Length parameter of the IEC-GOOSE part in the P-frame message frame structure to 8+m, set both the "I / P frame marker" and "I-frame feature marker" parameters to 0, then transmit the message to the next unit of the distributed distribution protection self-healing device and proceed to step S15.

[0090] S15: Continue reading the next frame of the message in the sequence. If there is one, proceed to step S11; otherwise, end the decoding.

[0091] This embodiment uses 15 consecutive messages as an example, setting N to 1. Due to the long message length, this embodiment only lists the relevant stNum and sqNum fields. Q1-Q11 are non-fault messages, Q12 and Q13 are fault messages, and Q14-Q15 are non-fault messages. The specific details are as follows:

[0092] Q1:…85 04 00 00 6F CB(stnum) 86 04 00 00 00 00(sqnum)…

[0093] Q2:…85 04 00 00 6F CB(stnum) 86 04 00 00 00 01(sqnum)…

[0094] Q3:…85 04 00 00 6F CB(stnum) 86 04 00 00 00 02(sqnum)…

[0095] Q4:…85 04 00 00 6F CB(stnum) 86 04 00 00 00 03(sqnum)…

[0096] Q5:…85 04 00 00 6F CB(stnum) 86 04 00 00 00 04(sqnum)…

[0097] Q6:…85 04 00 00 6F CC(stnum) 86 04 00 00 00 00(sqnum)…

[0098] Q7:…85 04 00 00 6F CC(stnum) 86 04 00 00 00 01(sqnum)…

[0099] Q8:…85 04 00 00 6F CC(stnum) 86 04 00 00 00 02(sqnum)…

[0100] Q9:…85 04 00 00 6F CC(stnum) 86 04 00 00 00 03(sqnum)…

[0101] Q10:…85 04 00 00 6F CC(stnum) 86 04 00 00 00 04(sqnum)…

[0102] Q11:…85 04 00 00 6F CD(stnum) 86 04 00 00 00 00(sqnum)…

[0103] Q12:…85 04 00 00 6F CE(stnum) 86 04 00 00 00 00(sqnum)…

[0104] Q13:…85 04 00 00 6F CF(stnum) 86 04 00 00 00 00(sqnum)…

[0105] Q14:…85 04 00 00 6F D0(stnum) 86 04 00 00 00 00(sqnum)…

[0106] Q15:…85 04 00 00 6F D0(stnum) 86 04 00 00 00 01(sqnum)…

[0107] The entire encoding system process, receiving Q1 through Q15 sequentially, is as follows:

[0108] Step 1: Initialize settings, set the counter to 0, and set the I-frame repeat period N to 1.

[0109] Step 2: Read in Q1, send the message directly, Δst n =0, Δsq n =0.

[0110] Step 3: Read in Q2 and calculate Δst n-1 =0, Δsq n-1 =0, Δst n =0, Δsq n=1. The conditions for entering the encoding waiting state are not met, so the message is transmitted directly.

[0111] Step 4: Read in Q3 and calculate Δst n-1 =0, Δsq n-1 =1, Δst n =0, Δsq n =1. The condition for entering the encoding waiting state is met, so the message is sent directly and the encoding waiting state is entered.

[0112] Step 5: Read in Q4 and calculate Δst n-1 =0, Δsq n-1 =1, Δst n =0, Δsq n =1. No conditions for entering any state were met; the message was sent directly.

[0113] Step 6: Read in Q5 and calculate Δst n-1 =0, Δsq n-1 =1, Δst n =0, Δsq n =1. No conditions for entering any state were met; the message was sent directly.

[0114] Step 7: Read in Q6 and calculate Δst n-1 =0, Δsq n-1 =1, Δst n =1, Δsq n =-4. The condition for entering the encoding state is met; therefore, the encoding state is entered, according to Δst. n-1 =0, Δsq n-1 =1, Δst n =1, Δsq n When the condition is -4, the counter ctn is incremented by 1, and ctn=1. The current frame is defined as an I-frame and buffered. The PDU data of the I-frame message is encoded using a lossless encoding method, and the parameter values ​​of the IEC-GOOSE part in the message frame structure are modified at the same time.

[0115] Step 8: Read in Q7 and calculate Δst n-1 =1, Δsq n-1 =-4, Δst n =0, Δsq n =1. Δst is not satisfied. n-1 =0, Δsq n-1 =1, Δst n =1, Δsq nGiven a condition of -4, define the current frame as a P-frame, calculate the residual between the PDU data of the P-frame message and the PDU data of the buffered I-frame message, encode the residual data using a lossless encoding method, replace the PDU data of the P-frame message with the encoded residual data, and simultaneously modify the parameter values ​​of the IEC-GOOSE part in the message frame structure.

[0116] Step 9: Read in Q8 and calculate Δst n-1 =0, Δsq n-1 =1, Δst n =0, Δsq n =1. Δst is not satisfied. n-1 =0, Δsq n-1 =1, Δst n =1, Δsq n Given a condition of -4, define the current frame as a P-frame, calculate the residual between the PDU data of the P-frame message and the PDU data of the buffered I-frame message, encode the residual data using a lossless encoding method, replace the PDU data of the P-frame message with the encoded residual data, and simultaneously modify the parameter values ​​of the IEC-GOOSE part in the message frame structure.

[0117] Step 9: Read in Q9 and calculate Δst n-1 =0, Δsq n-1 =1, Δst n =0, Δsq n =1. Δst is not satisfied. n-1 =0, Δsq n-1 =1, Δst n =1, Δsq n Given a condition of -4, define the current frame as a P-frame, calculate the residual between the PDU data of the P-frame message and the PDU data of the buffered I-frame message, encode the residual data using a lossless encoding method, replace the PDU data of the P-frame message with the encoded residual data, and simultaneously modify the parameter values ​​of the IEC-GOOSE part in the message frame structure.

[0118] Step 10: Read in Q10 and calculate Δst n-1 =0, Δsq n-1 =1, Δst n =0, Δsq n =1. Δst is not satisfied. n-1 =0, Δsq n-1 =1, Δst n =1, Δsq nGiven a condition of -4, define the current frame as a P-frame, calculate the residual between the PDU data of the P-frame message and the PDU data of the buffered I-frame message, encode the residual data using a lossless encoding method, replace the PDU data of the P-frame message with the encoded residual data, and simultaneously modify the parameter values ​​of the IEC-GOOSE part in the message frame structure.

[0119] Step 11: Read in Q11 and calculate Δst n-1 =0, Δsq n-1 =1, Δst n =1, Δsq n =-4. Increment the counter ctn by 1, ctn=2(N+1).

[0120] Step 12: The counter ctn is 2, which satisfies the condition that the counter equals N+1. The counter ctn is then set to 1.

[0121] Step 13: Based on Δst n-1 =0, Δsq n-1 =1, Δst n =1, Δsq n The condition =-4 defines the current frame as an I-frame and buffers it. The PDU data of the I-frame message is encoded using a lossless encoding method, and the parameter values ​​of the IEC-GOOSE part in the message frame structure are modified at the same time.

[0122] Step 14: Read in Q12 and calculate Δst n-1 =1, Δsq n-1 =-4, Δst n =1, Δsq n =0. The conditions for entering a fault state are met, so the message is sent directly, and the fault state is entered.

[0123] Step 15: Read in Q13, send the message directly, and calculate Δst. n-1 =1, Δsq n-1 =0, Δst n =1, Δsq n =0, the conditions for exiting the fault state are not met.

[0124] Step 16: Read in Q14, send the message directly, and calculate Δst. n-1 =1, Δsq n-1 =0, Δst n =1, Δsq n =0, the conditions for exiting the fault state are not met.

[0125] Step 17: Read in Q15, send the message directly, and calculate Δst. n-1 =1, Δsq n-1=0, Δst n =0, Δsq n =1, which satisfies the condition for exiting the fault state.

[0126] Step 18: Clear the counter to 0 and enter the encoding wait state.

[0127] Step 19: No next frame, end encoding.

[0128] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for transmitting GOOSE messages in a power distribution network protection and control device, characterized in that, The GOOSE messages are transmitted between distributed power distribution protection self-healing devices. Based on the Destination Mac and APPID parameters in the GOOSE message, the messages to be sent are sequentially assigned to different sequences. For any sequence, the following steps are included: S01: Initialization: Clear the counter cnt to zero and set the I-frame repeat period value to N; S02: Initial state: Read one frame of message sequentially, send the message directly without compression or encoding, and calculate Δst. n Δsq n According to Δst n-1 Δsq n-1 Δst n Δsq n If the conditions for entering the encoding waiting state are met, proceed to step S03; otherwise, repeat this step until no more messages to be sent are read. S03: Enter the encoding waiting state, continue reading 1 frame of the message in sequence, and calculate Δst. n Δsq n According to Δst n-1 Δsq n-1 Δst n Δsq n If the conditions for entering the fault state are met, the current frame message is sent directly without compression encoding, and then proceed to step S04; if the conditions for entering the encoding state are met, then according to Δst... n-1 Δsq n-1 Δst n Δsq n If the combination of conditions is not met, the current frame message is compressed and encoded and sent, and then the process proceeds to step S05; if none of the conditions are met, the current frame message is sent directly without compression and encoding, and this step is repeated until no more messages to be sent are read. S04: Entering fault state, continue reading 1 frame of message in sequence, send the current frame of message directly without compression encoding, and calculate Δst. n Δsq n According to Δst n-1 Δsq n-1 Δst n Δsq n If the conditions for exiting the fault state are met, the counter cnt is cleared and the process proceeds to step S03; otherwise, this step is repeated until no more messages to be sent are read. S05: Enter encoding state, continue reading 1 frame of message sequentially, and calculate Δst. n Δsq n According to Δst n-1 Δsq n-1 Δst n Δsq n If the conditions for entering a fault state are met, the current frame message is sent directly without compression encoding, and then proceed to step S04; otherwise, based on Δst... n-1 Δsq n-1 Δst n Δsq n The current frame message is compressed and encoded based on the combination of different conditions and then sent. This process is repeated until no more messages to be sent are read. For the nth frame message, Δst n = stNum n -stNum n-1 ,Δsq n = sqNum n -sqNum n-1 stNum n sqNum n These represent the stNum and sqNum parameters in the nth frame, where n ≥ 3; Δst is set when the first frame is read. n =Δst n-1 =0, Δsq n =Δsq n-1 =0, when the second frame of the message is read, Δst n-1 =0, Δsq n-1 =0; In steps S03 and S05, if Δst n-1 =0, Δsq n-1 =1, Δst n =1, Δsq n If the value is -4, then the current frame is defined as an I-frame and buffered. The PDU data of the I-frame message is encoded using a lossless encoding method, and the parameter values ​​of the IEC-GOOSE part in the message frame structure are modified. Otherwise, the current frame is defined as a P-frame. The residual between the PDU data of the P-frame message and the PDU data of the buffered I-frame message is calculated. The residual data is encoded using a lossless encoding method. The PDU data of the P-frame message is replaced with the encoded residual data, and the parameter values ​​of the IEC-GOOSE part in the message frame structure are modified.

2. The GOOSE message transmission method for distribution network protection and control devices according to claim 1, characterized in that, In step S02, the condition for entering the encoding waiting state is: Δst n-1 =0, Δsq n-1 =1, Δst n =0, Δsq n =1; In steps S03 and S05, the condition for entering the fault state is any one of the following five conditions: Δst n-1 =1,Δsq n-1 =0,Δst n =1,Δsq n =0; Δst n-1 =1,Δsq n-1 =-2,Δst n =1,Δsq n =0; Δst n-1 =1,Δsq n-1 =-1,Δst n =1,Δsq n =0; Δst n-1 =1,Δsq n-1 =-3,Δst n =1,Δsq n =0; Δst n-1 =1,Δsq n-1 =-4,Δst n =1,Δsq n =0; In step S03, the condition for entering the encoding state is: Δst n-1 =0, Δsq n-1 =1, Δst n =1, Δsq n =-4; In step S04, the condition for exiting the fault state is: Δst n-1 =1, Δsq n-1 =0, Δst n =0, Δsq n =1.

3. The GOOSE message transmission method for distribution network protection and control devices according to claim 2, characterized in that, In steps S03 and S05, according to Δst n-1 Δsq n-1 Δst n Δsq n The steps for compressing and encoding messages based on combinations of data include: S001: Based on the current frame message, if Δst n-1 =0, Δsq n-1 =1, Δst n =1, Δsq n If the value is -4, then the counter cnt is incremented by 1, and then the process proceeds to step S002; otherwise, the process proceeds directly to step S002. S002: Determine the value of counter cnt. If the value of counter cnt is equal to (N+1), set counter cnt=1 and proceed to step S003. Otherwise, proceed directly to step S003. S003: If Δst at this time n-1 =0, Δsq n-1 =1, Δst n =1, Δsq n If the value is -4, then the current frame is defined as an I-frame and buffered. The PDU data of the I-frame message is encoded using a lossless encoding method, and the parameter values ​​of the IEC-GOOSE part in the message frame structure are modified. Otherwise, the current frame is defined as a P-frame. The residual between the PDU data of the P-frame message and the PDU data of the buffered I-frame message is calculated. The residual data is encoded using a lossless encoding method. The PDU data of the P-frame message is replaced with the encoded residual data, and the parameter values ​​of the IEC-GOOSE part in the message frame structure are modified.

4. The GOOSE message transmission method for distribution network protection and control devices according to claim 3, characterized in that, In the compressed and encoded GOOSE message frame structure, the IEC-GOOSE part includes an "I / P frame tag" field and an "I frame feature tag" field. The "I frame feature tag" field is the stNum of the currently cached I frame message.

5. The GOOSE message transmission method for distribution network protection and control devices according to claim 4, characterized in that, The receiver classifies the received GOOSE messages into different decoding sequences for processing based on the APPID parameter in the message frame; For any sequence, the decompression process includes: S11: Read one frame of message in sequence. Based on the "I / P frame marker" parameter in the message, if it is an uncompressed message, it is directly transmitted to the distributed power distribution protection self-healing device, and then proceed to step S15; if it is an I frame message, proceed to step S12; if it is a P frame message, proceed to step S13. S12: For the PDU data in the I-frame message, use the inverse algorithm that matches the PDU data compression algorithm of the I-frame message to decode it, cache the I-frame message, and then set the "I / P frame mark" and "I frame feature mark" parameters of the IEC-GOOSE part in the frame structure of the I-frame message to 0. After that, transmit the message to the next unit of the distributed distribution protection self-healing device and proceed to step S15. S13: Determine if there is a buffered I-frame packet. If not, discard the P-frame packet and proceed to step S15. If there is, proceed to step S14. S14: Compare the "I-frame feature marker" in the current P-frame message with the "I-frame feature marker" in the cached I-frame message. If they are different, discard the received P-frame message and proceed to step S15. If they are the same, decode the PDU data in the current P-frame message using an inverse algorithm that matches the PDU residual data compression algorithm of the P-frame message to obtain the residual between the cached I-frame message PDU data and the P-frame PDU data. Then, recover the original P-frame PDU data based on the cached I-frame message PDU data. Set both the "I / P frame flag" and "I frame feature flag" parameters to 0, then transmit the message to the next unit of the distributed power distribution protection self-healing device, and proceed to step S15. S15: Continue reading the next frame of the message in the sequence. If there is one, proceed to step S11; otherwise, end the decoding.

6. The GOOSE message transmission method for distribution network protection and control devices according to claim 5, characterized in that, Configure a compression and transmission module for performing steps S01 to S05, the compression and transmission module being connected to at least one distributed power distribution protection self-healing device; configure a receiving and decompression module for performing steps S11 to S15, the receiving and decompression module being connected to at least one distributed power distribution protection self-healing device.

7. The GOOSE message transmission method for distribution network protection and control devices according to claim 6, characterized in that, The receiving and decompression module receives the GOOSE message, compares the Destination MAC parameter in the message, and determines whether it is a message sent to the distributed power distribution protection self-healing device connected to it. If not, the message is discarded.

8. The GOOSE message transmission method for distribution network protection and control devices according to any one of claims 3-7, characterized in that, The lossless coding methods include Huffman coding and run-length coding.

9. The GOOSE message transmission method for distribution network protection and control devices according to any one of claims 4-7, characterized in that, In the GOOSE message frame structure, the "I / P frame flag" is defined as 0000H when the message is not compressed, 0001H in I frames, and 0010H in P frames.

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