GOOSE message transmission method for power distribution network protection control device

Abstract

The invention discloses a GOOSE (Generic Object Oriented Substation Event) message transmission method of a power distribution network protection control device. The GOOSE message transmission method comprises a compression process and a decompression process of GOOSE messages. In the compression process, different coding states are entered according to different message states, so that the transmission resource consumption of the same data is remarkably reduced, and the compression ratio of the message is improved. The decompression process comprises two aspects of detection and discrimination of the compression type of the received message and decoding. According to the invention, the efficient and stable transmission of the fault message is ensured, and the reliability of the system is improved. Under the condition that the channel bandwidth is limited, resources can be effectively saved, the integrity, reliability and real-time performance of data transmission are ensured, the transmission efficiency of the message is greatly improved, and the real-time processing and application effect of the message is enhanced.

Description

Technical Field

[0001] The invention belongs to a power message data processing technology, and in particular relates to a GOOSE (Generic Object Oriented Substation Event, generic object oriented substation event) message transmission method. Background Art

[0002] Smart distribution networks use 5G communication networks to meet the transmission needs of distribution network protection and control services with their "three highs and two lows" characteristics (high speed, high capacity, high reliability, low latency, and low energy consumption), and have gradually become a hot spot for research and application in this field. However, in actual operation, the amount of data in distribution network protection and control services is extremely large, and direct transmission through 5G networks will significantly increase operating costs and resource usage. Therefore, it is particularly necessary to implement effective compression before data transmission.

[0003] Currently, the distribution network protection and control service mainly relies on the GOOSE message protocol for data transmission. In the non-fault state, the protection device periodically sends heartbeat messages at a time interval of T0, and retransmits the heartbeat messages at an interval of "T1-T1-T2-T3" during T0. Since there is a significant correlation between heartbeat messages, the use of data compression technology can effectively reduce the amount of data required to be transmitted. In the fault state, the protection device will send fault messages at a time interval much smaller than T0. In order to ensure the accuracy of fault message transmission, consider transparent transmission. However, the above message compression process relies on a fast fault detection mechanism.

[0004] In addition, GOOSE messages are usually transmitted in a multicast manner in the distribution network, that is, 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 message to ensure that the message 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 a distribution network protection and control device is proposed. Through the coding 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 of a distribution network protection control device, wherein the GOOSE messages are transmitted between distributed distribution protection self-healing devices, and messages to be sent are sequentially classified into different sequences according to the Destination Mac and APPID parameters in the GOOSE messages; for any sequence, the method comprises the following steps: S01: Initialization: Clear the counter cnt and set the I frame repetition period value to N; S02: Initial state: read 1 frame of message in order, send the message directly without compression coding, calculate Δst n , Δsq n , according to Δst n-1 , Δsq n-1 , Δst n , Δsq n If the condition for entering the encoding waiting state is met, then go to step S03, otherwise repeat this step until no more messages to be sent are read; S03: Enter the encoding waiting state, continue to read 1 frame of message in sequence, and calculate Δst n , Δsq n , according to Δst n-1 , Δsq n-1 , Δst n , Δsq n If the condition of entering the fault state is met, the current frame message is sent directly without compression coding, and then go to step S04; if the condition of entering the coding state is met, according to Δst n-1 , Δsq n-1 , Δst n , Δsq n The current frame message is compressed and encoded according to the combination of conditions and sent, and then the process goes to step S05; if none of them are satisfied, the current frame message is directly sent without compression encoding, and this step is repeated until no message to be sent is read; S04: Enter the fault state, continue to read 1 frame of messages in order, send the current frame message directly without compression coding, calculate Δst n , Δsq n , according to Δst n-1 , Δsq n-1 , Δst n , Δsq n If the condition for exiting the fault state is met, the counter cnt is reset and the process goes to step S03. Otherwise, this step is repeated until no more messages to be sent are read. S05: Enter the encoding state, continue to read 1 frame of messages in sequence, and calculate Δst n , Δsq n , according to Δst n-1 , Δsq n-1 , Δst n , Δsq n If the condition for entering the fault state is met, the current frame message is sent directly without compression coding, and then the process goes to step S04; otherwise, according to Δst n-1 , Δsqn-1 , Δst n , Δsq n The current frame message is compressed and encoded according to the combination of the current frame message and sent, and then this step is repeated until no message to be sent is read; Among them, for the nth frame message, Δst n =stNum n -stNum n-1 , Δsq n =sqNum n -sqNum n-1 ,stNum n 、sqNum n Respectively represent the stNum and sqNum parameters in the nth frame message, n ≥ 3; set to read the first frame message, Δst n =Δst n-1 =0,Δsq n =Δsq n-1 =0, when the second frame message is read, Δst n-1 =0,Δsq n-1 =0.

[0007] 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; In steps S03 and S05, the condition for entering the fault state is any one of the following five situations: 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.

[0008] Furthermore, in steps S03 and S05, according to Δst n-1 , Δsq n-1 , Δst n , Δsq n The steps of compressing and encoding the message according to the combination of the above-mentioned conditions include: S001: According to the current frame message, if Δst n-1 =0,Δsq n-1 =1,Δst n =1,Δsq n =-4, then the counter cnt is incremented by 1 and the process goes to step S002; otherwise, the process goes 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 go to step S003. Otherwise, go to step S003 directly. S003: If Δst n-1 =0,Δsq n-1 =1,Δst n =1,Δsq n =-4, the current frame is defined as an I frame and cached, the PDU data of the I frame message is encoded using a lossless coding method, and the parameter value of the IEC-GOOSE part in the message frame structure is 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 cached I frame message is solved, the residual data is encoded using a lossless coding method, the PDU data of the P frame message is replaced with the encoded residual data, and the parameter value of the IEC-GOOSE part in the message frame structure is modified.

[0009] 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, and the "I frame feature tag" field is the stNum of the currently cached I frame message.

[0010] Furthermore, the receiver classifies the received GOOSE message into different decoding sequences for processing according to the APPID parameter in the message frame; for any sequence, the decompression process includes: S11: read 1 frame message in sequence, and judge according to the "I / P frame mark" 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 go to step S15; if it is an I frame message, go to step S12; if it is a P frame message, go to step S13; S12: Decode the PDU data in the I frame message using an inverse algorithm that matches the PDU data compression algorithm of the I frame message, cache the I frame message, and then set the "I / P frame mark" and "I frame feature mark" parameters of the IEC-GOOSE part of the I frame message frame structure to 0, then transmit the message to the next unit of the distributed power distribution protection self-healing device, and go to step S15; S13: Determine whether there is an I frame message cached currently, if not, discard the P frame message and go to step S15, if yes, go to step S14; S14: compare the "I frame feature mark" in the current P frame message with the "I frame feature mark" in the cached I frame message. If they are not the same, discard the received P frame message and go 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 corresponding cached I frame message PDU data and the P frame PDU data, and then restore the original P frame PDU data based on the cached I frame message PDU data; set both the "I / P frame mark" and "I frame feature mark" parameters to 0, then transmit the message to the next unit of the distributed power distribution protection self-healing device, and go to step S15; S15: Continue to read the next frame message in the sequence in order, if there is one, go to step S11, otherwise end the decoding.

[0011] Furthermore, a compression and sending module is configured to execute steps S01 to S05, and the compression and sending module is connected to at least one distributed power distribution protection self-healing device; a receiving and decompression module is configured to execute steps S11 to S15, and the receiving and decompression module is connected to at least one distributed power distribution protection self-healing device.

[0012] 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 to which it is connected, and if not, discards the message.

[0013] Furthermore, the lossless coding method includes Huffman coding and run-length coding.

[0014] Furthermore, in the GOOSE message frame structure, the "I / P frame mark" is defined as 0000H when the message is not compressed, 0001H in the I frame, and 0010H in the P frame.

[0015] Beneficial effects: 1) The method of the present invention effectively removes redundant information between similar messages by repeatedly utilizing the same information in continuous message data, thereby significantly improving the compression ratio of the message.

[0016] 2) Fault detection mechanism design: Aiming at the GOOSE message sending mechanism, the present invention designs an efficient message fault detection mechanism by identifying the stNum and sqNum parameters in the message. This mechanism ensures the efficient and stable transmission of faulty messages and improves the reliability of the system.

[0017] 3) Frame loss and frame sequence discrimination mechanism: In order to solve the problems of frame loss and frame sequence reception errors that may occur in wireless transmission, this method designs a corresponding discrimination mechanism during the decoding process, which effectively reduces the impact of transmission errors on message decoding, thereby ensuring data integrity.

[0018] 4) Residual simplification and coding: By calculating the residual of the P frame relative to the I frame and encoding these residuals, the transmission of the same data can be effectively reduced, further improving the compression efficiency.

[0019] 5) Optimization of resource consumption and transmission efficiency: The method of the present invention significantly reduces the transmission resource consumption of the same data and improves the compression ratio of the message. In the case of limited channel bandwidth, this method can effectively save resources, ensure the integrity, reliability and real-time performance of data transmission, greatly improve the transmission efficiency of the message, and enhance the real-time processing and application effect of the message. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a compression state diagram in the present invention; Figure 2 It is a decompression flow chart of the method of the present invention; Figure 3 It is the original GOOSE message frame format; Figure 4 This is the compressed message format. DETAILED DESCRIPTION

[0021] The present invention will be further explained below in conjunction with the accompanying drawings.

[0022] This embodiment takes the GOOSE message as an example to illustrate the encoding process of the GOOSE message. The protocol belongs to the GOOSE message described in the present invention, and the protocol frame format is as follows:

[0023] The information represented by each field is as follows: Destination MAC——Destination address Source MAC——Source address Ethernet Type——Ethernet type value TPID - optional field TCI - optional field APPID——Application Identifier App Length——Length field Reserved1——Reserved bit 1 Reserved1——Reserved bit 2 PDU - Protocol Data Unit stNUM——state number, used to record the total number of times GOOSE data changes sqNUM——sequence number, used to record the number of frames sent by the message in steady state A method for transmitting GOOSE messages of a distribution network protection control device, wherein the GOOSE messages are transmitted between distributed distribution protection self-healing devices, and the system is configured with a compression sending module, which is connected to at least one distributed distribution protection self-healing device. The compression sending module receives the GOOSE messages sent by the connected distributed distribution protection self-healing device, and sequentially classifies the messages to be sent into different sequences according to the Destination Mac and APPID parameters in the GOOSE messages. For any sequence, the following steps are included: S01: Initialization: Clear the counter cnt and set the I frame repetition period value to N. The I frame repetition period N means that an I frame is set every N "heartbeat frames". In principle, N takes a value greater than or equal to 1. In actual projects, the value of N is set according to the compression rate requirements.

[0024] S02: Initial state: read 1 frame of message in order, send the message directly without compression coding, calculate Δst n , Δsq n , according to Δst n-1 , Δsq n-1 , Δst n , Δsq nIf the condition for entering the encoding waiting state is met, then go to step S03, otherwise repeat this step until no more messages to be sent are read.

[0025] S03: Enter the encoding waiting state, continue to read 1 frame of message in sequence, and calculate Δst n , Δsq n , according to Δst n-1 , Δsq n-1 , Δst n , Δsq n If the condition of entering the fault state is met, the current frame message is sent directly without compression coding, and then go to step S04; if the condition of entering the coding state is met, according to Δst n-1 , Δsq n-1 , Δst n , Δsq n The message is compressed and encoded and sent according to the combination of conditions, and then the process goes to step S05; if none of them are satisfied, the current frame message is directly sent without compression encoding, and this step is repeated until no message to be sent is read.

[0026] S04: Enter the fault state, continue to read 1 frame of messages in order, send the current frame message directly without compression coding, calculate Δst n , Δsq n , according to Δst n-1 , Δsq n-1 , Δst n , Δsq n If the condition for exiting the fault state is met, the counter cnt is cleared and the process goes to step S03 . Otherwise, this step is repeated until no more messages to be sent are read.

[0027] S05: Enter the encoding state, continue to read 1 frame of messages in sequence, and calculate Δst n , Δsq n , according to Δst n-1 , Δsq n-1 , Δst n , Δsq n If the condition for entering the fault state is met, the current frame message is sent directly without compression coding, and then the process goes to step S04; otherwise, according to Δst n-1 , Δsq n-1 , Δst n , Δsq n The message is compressed and encoded according to the combination of the two conditions and sent, and then this step is repeated until no message to be sent is read.

[0028] Among them, for the nth frame message, Δst n =stNumn -stNum n-1 , Δsq n =sqNum n -sqNum n-1 ,stNum n 、sqNum n Respectively represent the stNum and sqNum parameters in the nth frame message, n ≥ 3; set to read the first frame message, Δst n =Δst n-1 =0,Δsq n =Δsq n-1 =0, when the second frame message is read, Δst n-1 =0,Δsq n-1 =0.

[0029] 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.

[0030] In steps S03 and S05, the condition for entering the fault state is any one of the following five situations: 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.

[0031] 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.

[0032] In steps S03 and S05, according to Δst n-1 , Δsq n-1 , Δst n , Δsq n The steps of compressing and encoding the message according to the combination of the above-mentioned conditions include: S001: According to the current frame message, if Δst n-1 =0,Δsq n-1 =1,Δst n =1,Δsq n =-4, then the counter cnt is incremented by 1 and the process goes to step S002; otherwise, the process goes directly to step S002.

[0033] S002: Determine the value of counter cnt. If the value of counter cnt is equal to (N+1), set counter cnt=1 and go to step S003. Otherwise, go directly to step S003.

[0034] S003: If Δst n-1 =0,Δsq n-1 =1,Δst n =1,Δsq n =-4, the current frame is defined as an I frame and cached, and the PDU data of the I frame message is encoded using lossless coding methods such as Huffman coding and run-length coding, and the parameter value of the IEC-GOOSE part in the message frame structure is modified; otherwise, the current frame is defined as a P frame, and the residual between the PDU data of the P frame message and the PDU data of the cached I frame message is solved, and the residual data is encoded using lossless coding methods such as Huffman coding and run-length coding, and the PDU data of the P frame message is replaced with the encoded residual data, and the parameter value of the IEC-GOOSE part in the message frame structure is modified. In the GOOSE message frame structure after compression coding, the IEC-GOOSE part includes the "I / P frame mark" byte and the "I frame feature mark" field, and the "I frame feature mark" field is the stNum of the currently cached I frame message. In the GOOSE message frame structure, the "I / P frame mark" is defined as 0000H when the message is not compressed, 0001H in an I frame, and 0010H in a P frame.

[0035] The compressed and encoded GOOSE message frame structure is as follows:

[0036] Among them, the parameter values ​​are defined as follows: Length = 8 + n; "I / P frame mark" is 0000H (hexadecimal) when the message is not compressed, 0001H for I frame, and 0010H for P frame; "I frame feature mark" is the stNum of the currently cached I frame message; the remaining parameters keep the data values ​​in the original message unchanged.

[0037] The system is configured with a receiving and decompression module, which is connected to at least one distributed power distribution protection self-healing device. When receiving a GOOSE message, the receiving and decompression module first compares the Destination MAC parameter in the message to determine whether it is a message sent to the distributed power distribution protection self-healing device to which it is connected. If not, the message is discarded. Then, the receiving and decompression module classifies the received GOOSE message into different decoding sequences for processing according to the APPID parameter in the message frame. For any sequence, the decompression process includes: S11: Read 1 frame message in sequence, and judge according to the "I / P frame mark" 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 go to step S15; if it is an I frame message, go to step S12; if it is a P frame message, go to step S13.

[0038] S12: The PDU data in the I frame message is decoded by using an inverse algorithm that matches the PDU data compression algorithm of the I frame message. Assume that the decoded data length is m bytes, set the Length parameter of the IEC-GOOSE part in the frame structure of the I frame message to 8+m, 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, then transmit the message to the next unit of the distributed power distribution protection self-healing device, and go to step S15.

[0039] S13: Determine whether there is an I frame message cached currently. If not, discard the P frame message and go to step S15. If yes, go to step S14.

[0040] S14: Compare the "I frame feature mark" in the current P frame message with the "I frame feature mark" in the cached I frame message. If they are not the same, discard the received P frame message and go 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 corresponding cached I frame message PDU data and the P frame PDU data, and then restore the original P frame PDU data based on the cached I frame message PDU data. Assuming that 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 the "I / P frame mark" and "I frame feature mark" parameters to 0, and then transmit the message to the next unit of the distributed power distribution protection self-healing device, and go to step S15.

[0041] S15: Continue to read the next frame message in the sequence in order, if there is one, go to step S11, otherwise end the decoding.

[0042] This embodiment takes 15 consecutive messages as an example, and sets N to 1. Since the message is long, this embodiment only lists the relevant stNum and sqNum fields. Among them, Q1-Q11 are non-fault messages, Q12 and Q13 are fault messages, and Q14-Q15 are non-fault messages. The specific contents are as follows: Q1:…85 04 00 00 6F CB(stnum) 86 04 00 00 00 00(sqnum)… Q2:…85 04 00 00 6F CB(stnum) 86 04 00 00 00 01(sqnum)… Q3:…85 04 00 00 6F CB(stnum) 86 04 00 00 00 02(sqnum)… Q4:…85 04 00 00 6F CB(stnum) 86 04 00 00 00 03(sqnum)… Q5:…85 04 00 00 6F CB(stnum) 86 04 00 00 00 04(sqnum)… Q6:…85 04 00 00 6F CC(stnum) 86 04 00 00 00 00(sqnum)… Q7:…85 04 00 00 6F CC(stnum) 86 04 00 00 00 01(sqnum)… Q8:…85 04 00 00 6F CC(stnum) 86 04 00 00 00 02(sqnum)… Q9:…85 04 00 00 6F CC(stnum) 86 04 00 00 00 03(sqnum)… Q10:…85 04 00 00 6F CC(stnum) 86 04 00 00 00 04(sqnum)… Q11:…85 04 00 00 6F CD(stnum) 86 04 00 00 00 00(sqnum)… Q12:…85 04 00 00 6F CE(stnum) 86 04 00 00 00 00(sqnum)… Q13:…85 04 00 00 6F CF(stnum) 86 04 00 00 00 00(sqnum)… Q14:…85 04 00 00 6F D0(stnum) 86 04 00 00 00 00(sqnum)… Q15:…85 04 00 00 6F D0(stnum) 86 04 00 00 00 01(sqnum)… Receive Q1 to Q15 in sequence, the entire coding system process is as follows: Step 1: Initialize the settings, set the counter to 0, and set the I frame repetition period N to 1.

[0043] Step 2: Read Q1 and send the message directly, Δst n =0,Δsq n =0.

[0044] Step 3: Read Q2 and calculate Δst n-1 =0,Δsq n-1 =0,Δst n =0,Δsq n = 1. The condition for entering the encoding waiting state is not met, and the message is transmitted directly.

[0045] Step 4: Read Q3 and calculate Δst n-1 =0,Δsq n-1 =1,Δst n =0,Δsq n =1. If the conditions for entering the encoding waiting state are met, the message is sent directly and the encoding waiting state is entered.

[0046] Step 5: Read Q4 and calculate Δst n-1 =0,Δsq n-1 =1,Δst n =0,Δsq n = 1. If the conditions for entering any state are not met, the message is sent directly.

[0047] Step 6: Read Q5 and calculate Δst n-1 =0,Δsq n-1 =1,Δst n =0,Δsq n = 1. If the conditions for entering any state are not met, the message is sent directly.

[0048] Step 7: Read 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, and the encoding state is entered. According to Δst n-1 =0,Δsq n-1 =1,Δst n =1,Δsq n =-4 condition, the counter ctn is increased by 1, ctn = 1. Define the current frame as an I frame and cache it, encode the PDU data of the I frame message using a lossless encoding method, and modify the parameter value of the IEC-GOOSE part in the message frame structure.

[0049] Step 8: Read Q7 and calculate Δst n-1 =1,Δsq n-1 =-4, Δst n =0,Δsq n =1. Does not satisfy Δst n-1 =0,Δsq n-1 =1,Δst n =1,Δsq n =-4 condition, define the current frame as a P frame, solve the residual of the PDU data of the P frame message and the PDU data of the cached I frame message, encode the residual data using a lossless coding method, replace the PDU data of the P frame message with the encoded residual data, and modify the parameter value of the IEC-GOOSE part in the message frame structure.

[0050] Step 9: Read Q8 and calculate Δst n-1 =0,Δsq n-1 =1,Δst n =0,Δsq n =1. Does not satisfy Δst n-1 =0,Δsqn-1 =1,Δst n =1,Δsq n =-4 condition, define the current frame as a P frame, solve the residual of the PDU data of the P frame message and the PDU data of the cached I frame message, encode the residual data using a lossless coding method, replace the PDU data of the P frame message with the encoded residual data, and modify the parameter value of the IEC-GOOSE part in the message frame structure.

[0051] Step 9: Read Q9 and calculate Δst n-1 =0,Δsq n-1 =1,Δst n =0,Δsq n =1. Does not satisfy Δst n-1 =0,Δsq n-1 =1,Δst n =1,Δsq n =-4 condition, define the current frame as a P frame, solve the residual of the PDU data of the P frame message and the PDU data of the cached I frame message, encode the residual data using a lossless coding method, replace the PDU data of the P frame message with the encoded residual data, and modify the parameter value of the IEC-GOOSE part in the message frame structure.

[0052] Step 10: Read Q10 and calculate Δst n-1 =0,Δsq n-1 =1,Δst n =0,Δsq n =1. Does not satisfy Δst n-1 =0,Δsq n-1 =1,Δst n =1,Δsq n =-4 condition, define the current frame as a P frame, solve the residual of the PDU data of the P frame message and the PDU data of the cached I frame message, encode the residual data using a lossless coding method, replace the PDU data of the P frame message with the encoded residual data, and modify the parameter value of the IEC-GOOSE part in the message frame structure.

[0053] Step 11: Read Q11 and calculate Δst n-1 =0,Δsq n-1 =1,Δst n =1,Δsq n = -4. The counter ctn is incremented by 1, ctn = 2 (N + 1).

[0054] Step 12: The counter ctn is 2, which satisfies the condition that the counter is equal to N+1, and the counter ctn is set to 1.

[0055] Step 13: According to Δst n-1 =0,Δsq n-1 =1,Δst n =1,Δsq n =-4 condition, define the current frame as an I frame and cache it, encode the PDU data of the I frame message using a lossless encoding method, and modify the parameter value of the IEC-GOOSE part in the message frame structure.

[0056] Step 14: Read Q12 and calculate Δst n-1 =1,Δsq n-1 =-4, Δst n =1,Δsq n = 0. If the message enters the fault state, the message is sent directly and enters the fault state.

[0057] Step 15: Read Q13, send the message directly, and calculate Δst n-1 =1,Δsq n-1 =0,Δst n =1,Δsq n =0, the exit fault state condition is not met.

[0058] Step 16: Read Q14, send the message directly, and calculate Δst n-1 =1,Δsq n-1 =0,Δst n =1,Δsq n =0, the exit fault state condition is not met.

[0059] Step 17: Read Q15, send the message directly, and calculate Δst n-1 =1,Δsq n-1 =0,Δst n =0,Δsq n =1, the condition for exiting the fault state is met.

[0060] Step 18: Clear the counter to 0 and enter the encoding waiting state.

[0061] Step 19: There is no next frame, and the encoding ends.

[0062] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A GOOSE message transmission method for a distribution network protection control device, characterized in that: The GOOSE message is transmitted between distributed power distribution protection self-healing devices. According to the Destination Mac and APPID parameters in the GOOSE message, the messages to be sent are sequentially classified into different sequences; for any sequence, the following steps are included: S01: Initialization: Clear the counter cnt and set the I frame repetition period value to N; S02: Initial state: read 1 frame of message in order, send the message directly without compression coding, calculate Δst n , Δsq n , according to Δst n-1 , Δsq n-1 , Δst n , Δsq n If the condition for entering the encoding waiting state is met, then go to step S03, otherwise repeat this step until no more messages to be sent are read; S03: Enter the encoding waiting state, continue to read 1 frame of message in sequence, and calculate Δst n , Δsq n , according to Δst n-1 , Δsq n-1 , Δst n , Δsq n If the condition of entering the fault state is met, the current frame message is sent directly without compression coding, and then go to step S04; if the condition of entering the coding state is met, according to Δst n-1 , Δsq n-1 , Δst n , Δsq n The current frame message is compressed and encoded according to the combination of conditions and sent, and then the process goes to step S05; if none of them are satisfied, the current frame message is directly sent without compression encoding, and this step is repeated until no message to be sent is read; S04: Enter the fault state, continue to read 1 frame of messages in order, send the current frame message directly without compression coding, calculate Δst n , Δsq n , according to Δst n-1 , Δsq n-1 , Δst n , Δsq n If the condition for exiting the fault state is met, the counter cnt is reset and the process goes to step S03. Otherwise, this step is repeated until no more messages to be sent are read. S05: Enter the encoding state, continue to read 1 frame of messages in sequence, and calculate Δst n , Δsq n , according to Δst n-1 , Δsq n-1 , Δst n , Δsq n If the condition for entering the fault state is met, the current frame message is sent directly without compression coding, and then the process goes to step S04; otherwise, according to Δst n-1 , Δsq n-1 , Δst n , Δsq n The current frame message is compressed and encoded according to the combination of the current frame message and sent, and then this step is repeated until no message to be sent is read; Among them, for the nth frame message, Δst n =stNum n -stNum n-1 , Δsq n =sqNum n -sqNum n-1 ,stNum n 、sqNum n Respectively represent the stNum and sqNum parameters in the nth frame message, n ≥ 3; set to read the first frame message, Δst n =Δst n-1 =0,Δsq n =Δsq n-1 =0, when the second frame message is read, Δst n-1 =0,Δsq n-1 =0.

2. The GOOSE message transmission method for distribution network protection and control device 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 situations: 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 device 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 of compressing and encoding the message according to the combination of the above-mentioned conditions include: S001: According to the current frame message, if Δst n-1 =0,Δsq n-1 =1,Δst n =1,Δsq n =-4, then the counter cnt is incremented by 1 and the process goes to step S002; otherwise, the process goes 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 go to step S003. Otherwise, go to step S003 directly. S003: If Δst n-1 =0,Δsq n-1 =1,Δst n =1,Δsq n =-4, the current frame is defined as an I frame and cached, the PDU data of the I frame message is encoded using a lossless coding method, and the parameter value of the IEC-GOOSE part in the message frame structure is 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 cached I frame message is solved, the residual data is encoded using a lossless coding method, the PDU data of the P frame message is replaced with the encoded residual data, and the parameter value of the IEC-GOOSE part in the message frame structure is modified.

4. The GOOSE message transmission method for distribution network protection and control device according to claim 3 is characterized in that: In the GOOSE message frame structure after compression encoding, the IEC-GOOSE part includes an "I / P frame tag" field and an "I frame feature tag" field, and 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 device according to claim 4, characterized in that: The receiver classifies the received GOOSE message into different decoding sequences for processing according to the APPID parameter in the message frame; For any sequence, the decompression process includes: S11: read 1 frame message in sequence, and judge according to the "I / P frame mark" 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 go to step S15; if it is an I frame message, go to step S12; if it is a P frame message, go to step S13; S12: Decode the PDU data in the I frame message using an inverse algorithm that matches the PDU data compression algorithm of the I frame message, cache the I frame message, and then set the "I / P frame mark" and "I frame feature mark" parameters of the IEC-GOOSE part of the I frame message frame structure to 0, then transmit the message to the next unit of the distributed power distribution protection self-healing device, and go to step S15; S13: Determine whether there is an I frame message cached currently, if not, discard the P frame message and go to step S15, if yes, go to step S14; S14: compare the "I frame feature mark" in the current P frame message with the "I frame feature mark" in the cached I frame message. If they are different, discard the received P frame message and go 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 corresponding cached I frame message PDU data and the P frame PDU data, and then restore the original P frame PDU data based on the cached I frame message PDU data. Set the "I / P frame mark" and "I frame feature mark" parameters to 0, then transmit the message to the next unit of the distributed power distribution protection self-healing device, and go to step S15; S15: Continue to read the next frame message in the sequence in order, if there is one, go to step S11, otherwise end the decoding.

6. The GOOSE message transmission method for distribution network protection and control device according to claim 5, characterized in that: A compression and sending module is configured to execute steps S01 to S05, and the compression and sending module is connected to at least one distributed power distribution protection self-healing device; a receiving and decompression module is configured to execute steps S11 to S15, and the receiving and decompression module is connected to at least one distributed power distribution protection self-healing device.

7. The GOOSE message transmission method for distribution network protection and control device 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 to which it is connected, and if not, discards the message.

8. The method for transmitting a GOOSE message of a distribution network protection and control device according to any one of claims 3 to 7, characterized in that: The lossless coding method includes Huffman coding and run-length coding.

9. The method for transmitting a GOOSE message of a distribution network protection and control device according to any one of claims 4 to 7, characterized in that: In the GOOSE message frame structure, the "I / P frame mark" is defined as 0000H when the message is not compressed, 0001H in an I frame, and 0010H in a P frame.

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