Traveling wave distance measurement method and module based on online speed measurement

Abstract

The invention relates to a traveling wave distance measurement method and module based on online speed measurement, and belongs to the field of automatic control application of a power system. Comprising two traveling wave distance measurement modules, and each traveling wave distance measurement module is composed of a distance measurement CPU, an FPGA, a dual-port RAM, an SFP single-mode optical module, an AD sampling module, a PT / CT conversion module, a PWM module and a COM communication module. The method has the advantages that the stability of timing time, sampling time and communication delay of traveling wave devices at the two ends is guaranteed by adopting a hard real-time design without participation of a distance measurement CPU, the communication delay time is calculated online through a hard real-time algorithm, and distance measurement errors caused by time synchronization in the double-end traveling wave distance measurement process are greatly reduced; on-line measurement of wave velocities of traveling waves with different frequencies is realized by adopting an on-line velocity measurement method, and distance measurement errors caused by inaccurate wave velocities are reduced; therefore, the reliability and the accuracy of fault traveling wave distance measurement are improved.

Description

Technical Field

[0001] The invention relates to a traveling wave ranging method and a module based on online speed measurement, and belongs to the field of automatic control application of power systems. Background Art

[0002] Traveling wave ranging is to determine the fault location by using the propagation time of transient traveling waves generated by the fault on the power line. When a fault occurs in the power system, the fault point will emit traveling waves to both ends of the line, and these traveling waves propagate on the line at a speed close to the speed of light. By measuring the time difference between the traveling wave reaching the measuring points at both ends of the line, the distance from the fault point to the measuring points at both ends can be calculated, thereby determining the fault location. This method is called the two-end ranging method. This method needs to determine three data to calculate the fault location: line length L, traveling wave velocity v, and the time difference △t when the traveling wave reaches the measuring points at both ends. At present, the line length L and the traveling wave velocity v are both set manually in practical applications, and the time difference △t is calculated by the timing function of the global positioning system (GPS). The line length L can be measured manually, but the traveling wave velocity v is related to the material, insulation medium, installation method, environment, traveling wave frequency, etc. of the line and is difficult to calculate accurately, becoming a major factor affecting the accuracy of traveling wave ranging; at the same time, because the traveling wave velocity v is close to the speed of light, the small GPS timing difference and the software processing delay difference of the ranging CPU will lead to a large fault location error. Summary of the invention

[0003] In order to solve the two main problems mentioned above, the present invention proposes a traveling wave ranging method and module based on online speed measurement for high-voltage transmission lines and important distribution lines with optical fiber communication, especially cable lines deeply buried in the ground that require accurate fault location, and mine cable lines that affect personal safety. First, a hard real-time design without the participation of the ranging CPU is adopted to ensure the stability of the timing time, sampling time and communication delay of the traveling wave devices at both ends, and the communication delay time is calculated online through a hard real-time algorithm; second, an online speed measurement method is used to realize online real-time measurement of the traveling wave speeds of different frequencies.

[0004] In order to achieve the above-mentioned objectives, the technical scheme adopted by the present invention is as follows: a traveling wave ranging module based on online speed measurement, comprising two traveling wave ranging modules, each traveling wave ranging module consisting of a ranging CPU, an FPGA, a dual-port RAM, an SFP single-mode optical module, an AD sampling module, a PT / CT conversion module, a PWM module, and a COM communication module; the dual-port RAM realizes data exchange between the ranging CPU and the FPGA; the SFP single-mode optical module realizes long-distance optical fiber communication between the two traveling wave ranging modules; the AD sampling module realizes traveling wave voltage and current sampling; the PT / CT conversion module realizes traveling wave voltage and current conversion; the PWM module receives a pulse wave of variable frequency from the FPGA, realizes pulse wave conditioning and outputs it to a voltage transformer used as a power supply; the two traveling wave ranging modules are respectively installed in two traveling wave ranging devices or two distribution terminals; the traveling wave ranging devices or the distribution terminals provide working power to the traveling wave ranging modules; the two traveling wave ranging devices or the distribution terminals are installed at both ends of the power line.

[0005] In a preferred implementation scheme, the ranging CPU and the dual-port RAM, the FPGA and the dual-port RAM are connected via a 16-bit parallel bus, the ranging CPU and the COM communication module are connected via a full-duplex serial bus, the FPGA and the AD sampling module are connected via a 16-bit parallel bus, the AD sampling module and the PT / CT conversion module are connected via a high-frequency signal line, the FPGA and the SFP single-mode optical module are connected via a full-duplex differential bus, and the FPGA and the PWM module are connected via a high-speed IO port.

[0006] Furthermore, the FPGA uses a 100MHz constant temperature crystal oscillator and an AD sampling module with a high sampling rate of GSPS. The FPGA periodically starts the AD sampling module to sample and save the sampled data. The sampling frequency is 100MHz. The ranging CPU uses a quad-core ARM chip with a main frequency of more than 1.2GHz and a computing power of more than 2TOPS.

[0007] In a preferred embodiment, the optical fiber communication between the two traveling wave ranging modules uses data frames of equal length in a unified format.

[0008] Specifically, the data frame contains the following data:

[0009] There are 4 types of message types: 1-heartbeat sending, 2-heartbeat return, 3-traveling wave ranging sending, 4-traveling wave speed measurement sending;

[0010] This side sends the timestamp, which is valid for message types 1, 3, and 4;

[0011] The opposite side receives the time stamp. This data is valid for message type 2.

[0012] The opposite side sends the timestamp. This data is valid for message type 2.

[0013] The frequency of the wave head on this side is 1. This data is valid for message type 3, and other message types are filled with 0;

[0014] The time mark of the wave head on this side is 1. This data is valid for message type 3, and other message types are filled with 0; ...

[0016] The frequency of the wave head on this side is 10. This data is valid for message type 3, and other message types are filled with 0;

[0017] The time mark of the wave head on this side is 10. This data is valid for message type 3, and 0 is filled in for other message types;

[0018] The speed measurement wave frequency on this side is valid for message type 4;

[0019] The time stamp of the speed measurement wave on this side is valid for message type 4;

[0020] Frame sequence number, this data is used to determine whether the message is lost;

[0021] CRC16, this data is the CRC check code, which is used to determine whether the frame message is correct.

[0022] The present invention also discloses a traveling wave ranging method based on online speed measurement, which uses two FPGAs of traveling wave ranging modules to calculate the delay of optical fiber communication. The specific steps are as follows:

[0023] A1, the FPGA on this side determines whether the 1-minute timing has expired. If so, it goes to A2, otherwise it goes to A1;

[0024] A2: The FPGA on this side determines whether it is sending data. If so, it goes to A2; otherwise, it goes to A3.

[0025] A3, the FPGA on this side sends a message of type 1, which contains the time stamp of the sending on this side. The time stamp of the sending on this side is the 64-bit counter value SCount1 of the FPGA on this side, and then goes to A4;

[0026] A4: The FPGA on this side determines whether it has received a message of type 2 sent by the other side. If so, it goes to A5. Otherwise, if it has not received the message within 1 second, it sets the communication abnormal flag and goes to A1.

[0027] A5. The FPGA on this side records the arrival time mark SCount2 of the type 2 message received on this side, and extracts the opposite side receiving time mark and the opposite side sending time mark from the message. The opposite side receiving time mark and the opposite side sending time mark are the 64-bit counter values ​​PCount1 and PCount2 of the opposite side FPGA respectively, and then calculates the optical fiber communication delay time Tdelay:

[0028] Tdelay=[(SCount2-SCount1)-(PCount2-PCount1)] / 2,

[0029] Calculate the deviation value δCnt of the counters at both ends:

[0030] δCnt=PCount1-SCount1-Tdelay,

[0031] Finally, Tdelay and δCnt are updated and stored, and the communication normal flag is set and saved to the dual-port RAM on this side, and then go to A1.

[0032] In a preferred embodiment, an online measurement method is used to measure the traveling wave speed at different frequencies in real time to generate a traveling wave frequency-speed relationship table.

[0033] The specific steps for generating the traveling wave frequency-speed relationship table are as follows:

[0034] B1, the FPGA on this side initializes the traveling wave frequency ft = 10kHz, and then goes to B2;

[0035] B2, the FPGA on this side sends a pulse wave with a frequency of ft and a duration of 300 μs, and stores the FPGA clock counter value SCountt of the first rising edge (which is used as the time mark of the speed measurement wave on this side), and then goes to B3;

[0036] B3, the FPGA on this side fills the relevant data such as the speed measurement wave frequency Sft=ft on this side and the speed measurement wave time scale SCountt on this side into the type 4 message, and sends it to the traveling wave ranging module on the other side, and then goes to B4;

[0037] B4. The opposite FPGA reads the opposite sampling data PValue, increases the opposite sampling time stamp PCount, and writes the opposite sampling data group [PCount, PValue] cyclically into the opposite dual-port RAM; the opposite FPGA determines whether to start recording based on whether the traveling wave mutation amount is greater than the traveling wave threshold value. If the recording is started, it generates traveling wave waveform data of 400μs, 100μs before the recording starts and 300μs after the recording starts (i.e., the following three-phase current / voltage traveling wave recording data);

[0038] The opposite side ranging CPU uses Karenbauer transformation to obtain the traveling wave line mode component from the latest 400μs three-phase current / voltage traveling wave recording data stored in the opposite side dual-port RAM, and then performs Hilbert-Huang Transform (HHT) and differential operation on the line mode component to obtain the relationship between the amplitude and time of the traveling wave line mode components of different frequencies, where PCount is the sampling time corresponding to the opposite side sampling data PValue, and PValue is the traveling wave current / voltage amplitude collected on the opposite side; go to B5;

[0039] B5, the ranging CPU on the other side determines whether it has received the type 4 message on the local side. If so, it goes to B6, otherwise to B5;

[0040] B6. The distance measurement CPU on the other side parses the type 4 message on this side, extracts the speed measurement wave frequency Sft and the speed measurement wave time scale SCountt on this side, and obtains the time scale SCounttcal corresponding to the speed measurement wave frequency Sft on this side through the relationship between the wave frequency and time in step B4. First, calculate the clock counter difference △Cnt1 of the two wave head time scales:

[0041] △Cnt1=SCounttcal-(SCountt-δCnt), where δCnt is the deviation value of the two-end counters obtained in the specific steps of implementing high-precision calculation of heartbeat signal and optical fiber communication delay by FPGA;

[0042] Then calculate the absolute time difference △T1 between the two wave heads:

[0043] △T1=△Cnt1 / Ffpga, where Ffpga is the operating frequency of FPGA (the operating frequencies of the FPGA on this side and the opposite side are equal), which is 100MHz;

[0044] Finally, calculate the traveling wave velocity vt:

[0045] vt = L / △T1, where L is the line length (i.e. the length of the line between the two traveling wave ranging modules);

[0046] Go to B7;

[0047] B7, the distance measurement CPU on the opposite side stores the speed measurement traveling wave frequency Sft and the traveling wave speed vt on the local side into the traveling wave frequency-speed relationship table; go to B8;

[0048] B8. Set the traveling wave frequency ft of the FPGA on this side to 100kHz, 200kHz, 300kHz, 400kHz, 500kHz, 600kHz, 700kHz, 800kHz, and 900kHz respectively, and execute steps B2-B7 for each traveling wave frequency respectively.

[0049] In a preferred embodiment, the ranging CPU and FPGA of the two traveling wave ranging modules cooperate to realize the calculation of the traveling wave ranging time.

[0050] The specific steps of traveling wave ranging time calculation are as follows:

[0051] C1, the FPGA on this side reads the sampling data SValue on this side, increases the sampling time stamp SCount on this side, writes the sampling data group [SCount, SValue] on this side cyclically into the dual-port RAM1 area on this side, and then goes to C2;

[0052] C2, when the FPGA on this side determines that the traveling wave mutation amount is greater than the traveling wave threshold value, it starts the traveling wave recording, and then goes to C3, otherwise it goes to C1;

[0053] C3, the FPGA on this side stores the complete traveling wave waveform data of 400μs, 100μs before the start of recording and 300μs after the start, into the dual-port RAM1 area on this side, stops writing to the dual-port RAM1 area on this side, and switches to cyclically writing the traveling wave data into the dual-port RAM2 area on this side, and goes to C4;

[0054] C4, the local ranging CPU uses Karenbauer transformation to obtain the traveling wave line mode component from the latest 400μs three-phase current traveling wave recording data in the local dual-port RAM1 area, and then obtains the relationship between the amplitude and time of the traveling wave components of different frequencies after Hilbert-Huang Transform (HHT) and differential operation on the traveling wave line mode component; searches for the frequency point with the largest amplitude and greater than the traveling wave threshold value in the range of 10 frequency bands [10kHz, 100kHz), [100kHz, 200kHz), ..., [900kHz, 1000kHz), and records the local frequency data group [Sfi, SCountSti], where i = 1-10, Sfi is the local frequency value (i.e., the wave head frequency on this side), SCountSti is the wave head time mark on this side, and the wave head time mark of the frequency point with an amplitude less than the traveling wave threshold value is cleared to 0, and then goes to C5;

[0055] C5, the local ranging CPU fills the data of the local frequency data group into the type 3 message, and sends it to the other side traveling wave ranging module through the local FPGA, and then goes to C6;

[0056] C6, the ranging CPU on this side determines whether it has received the type 3 message from the other side. If so, it goes to C7. Otherwise, if it still has not received the message within 1 second, it sets the ranging time invalid flag;

[0057] C7. The local ranging CPU parses the opposite type 3 message and obtains the opposite frequency data group [Pfi, PCountSti], and compares it with the local frequency data group [Sfi, SCountSti] to obtain the local wave head time mark SCountSt, the opposite wave head time mark PCountSt, and the wave head frequency f, which have equal frequency values, the smallest frequency value, and wave head time marks that are not equal to 0. First calculate the counter difference △Cnt2 of the two wave head time marks:

[0058] △Cnt2=SCountSt-(PCountSt-δCnt), where δCnt is the deviation value of the counters at both ends;

[0059] Then calculate the absolute time difference △T2 between the two wave heads:

[0060] △T2=△Cnt2 / Ffpga; where Ffpga is the operating frequency of FPGA, which is 100MHz;

[0061] Finally, go to C8;

[0062] C8. The local ranging CPU looks up the closest traveling wave speed v from the traveling wave frequency-speed relationship table based on the wave head frequency f, and calculates the distance x from the fault point to the local traveling wave module: x=[L+△T2*v] / 2.

[0063] The benefits of the present invention are as follows: the present invention proposes a traveling wave ranging method and module based on online speed measurement for high-voltage transmission lines and important distribution lines with optical fiber communication, especially cable lines deeply buried in the ground that require accurate fault location, and mine cable lines that affect personal safety. By adopting a hard real-time design that does not require the participation of a ranging CPU to ensure the stability of the timing time, sampling time and communication delay of the traveling wave devices at both ends, and calculating the communication delay time online through a hard real-time algorithm, the ranging error caused by time synchronization in the two-end traveling wave ranging process is greatly reduced; by adopting an online speed measurement method to achieve online measurement of the speed of traveling waves of different frequencies, the ranging error caused by inaccurate speed is reduced; thereby improving the reliability and accuracy of fault traveling wave ranging. Since the devices on both sides of the present invention can calculate the fault distance independently, there is no need to transmit the traveling wave recording data to the platform for processing, thereby simplifying the system design link and saving costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 The hardware architecture diagram of the traveling wave ranging module based on online speed measurement of the present invention;

[0065] Figure 2 It is a schematic diagram of the communication message format of the present invention;

[0066] Figure 3It is a flow chart of FPGA heartbeat signal and optical fiber communication delay calculation of the present invention;

[0067] Figure 4 It is a flow chart of online measurement of traveling wave velocity of the present invention;

[0068] Figure 5 It is a flow chart of the traveling wave ranging calculation of the present invention. DETAILED DESCRIPTION

[0069] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0070] like Figure 1 As shown in the hardware architecture diagram of the traveling wave ranging module based on online speed measurement, it includes two traveling wave ranging modules. The two traveling wave ranging modules include a double-end traveling wave ranging mainboard (traveling wave board 1 and traveling wave board 2) and various modules integrated in the double-end traveling wave ranging mainboard. Each traveling wave ranging module is composed of a ranging CPU, FPGA, dual-port RAM, SFP single-mode optical module, AD sampling module, PT / CT conversion module, PWM module, and COM communication module; the dual-port RAM realizes large-scale data exchange between the ranging CPU and FPGA; the SFP single-mode optical module realizes long-distance optical fiber communication between the two traveling wave ranging modules; the AD sampling module realizes traveling wave voltage and current sampling, and the PT / CT conversion module realizes traveling wave voltage and current conversion; the PWM module receives a pulse wave of variable frequency from the FPGA, realizes pulse wave conditioning and outputs it to a voltage transformer used as a power supply (for example, a phase-to-phase PT or a dedicated PT provided by the line, the PT is installed near the traveling wave ranging module, the phase-to-phase PT refers to a voltage transformer between different phases, and the dedicated PT refers to a voltage transformer dedicated to the traveling wave ranging module of the present invention); after the pulse wave is output to the voltage transformer, it is coupled to the line to generate traveling waves of different frequencies for speed measurement. The COM communication module is used for communication between the ranging CPU and other local boards (such as the distribution terminal mainboard) or devices (such as monitoring equipment). For example, the distribution terminal mainboard sends configuration information (the configuration information includes the traveling wave threshold value, etc.) to the traveling wave ranging module, and the traveling wave ranging module can also send fault traveling wave waveform and other information to the monitoring equipment through the ranging CPU; the two traveling wave ranging modules can be installed in two traveling wave ranging devices or two distribution terminals (as two ends) respectively; the traveling wave ranging device or the distribution terminal provides working power to the traveling wave ranging module; the two traveling wave ranging devices or the distribution terminals are installed at both ends of the power line, and they are connected by single-mode optical fiber.

[0071] The interphase PT or dedicated PT mentioned above is a primary high voltage PT, and the PT / CT conversion module further converts the primary high voltage PT signal into a traveling wave voltage and current. The AD sampling module collects the traveling wave signal converted by the PT / CT conversion module and sends it to the FPGA for processing.

[0072] In this paper, the traveling wave is divided into the speed measurement traveling wave emitted by the FPGA and the fault traveling wave emitted by the line fault position. The acquisition path of the speed measurement traveling wave emitted by the FPGA includes: the speed measurement traveling wave (pulse wave) emitted by the FPGA on one side - the PWM module on one side - the voltage transformer on one side - the line - the voltage / current transformer on the other side - the PT / CT conversion module on the other side - the AD sampling module on the other side - the FPGA on the other side saves the traveling wave waveform. The acquisition path of the fault traveling wave emitted by the line fault position includes: the line fault position emits the fault traveling wave - the lines on both sides - the voltage / current transformers on both sides - the PT / CT conversion modules on both sides - the AD sampling modules on both sides - the FPGA on both sides saves the traveling wave waveform.

[0073] Among them, when coupling from the low voltage side to the high voltage side, a voltage transformer is used; when coupling from the high voltage side to the low voltage side, a voltage transformer or a current transformer is used.

[0074] In this article, two ends refer to both sides, including the current side and the opposite side.

[0075] The ranging CPU (central processing unit) and the dual-port RAM (random access memory), the FPGA (field programmable gate array processor) and the dual-port RAM are connected through a 16-bit parallel bus, the ranging CPU and the COM communication module are connected through a full-duplex serial bus, the FPGA and the AD sampling module are connected through a 16-bit parallel bus, the AD (analog-to-digital conversion) sampling module and the PT / CT conversion module (where PT refers to voltage conversion and CT refers to current conversion) are connected through a high-frequency signal line, the FPGA and the SFP single-mode optical module are connected through a full-duplex differential bus, and the FPGA and the PWM (pulse width modulation) module are connected through a high-speed IO port.

[0076] In order to achieve high timing accuracy and stable high sampling rate, FPGA adopts 100MHz high-precision constant temperature crystal oscillator and flash AD sampling module with GSPS high sampling rate. FPGA starts AD sampling module regularly to sample and save sampling data, and the sampling frequency is 100MHz. In order to meet the analysis requirements of traveling wave recording waveform data, the ranging CPU adopts a domestically produced quad-core ARM chip with a main frequency of more than 1.2GHz, with a computing power of more than 2TOPS (processor computing power unit).

[0077] Figure 2 This is a schematic diagram of the communication message format of the present invention. In order to simplify the communication message processing and stabilize the message processing time, the optical fiber communication between the two traveling wave ranging modules adopts a data frame of equal length in a unified format. The data frame contains the following data:

[0078] There are 4 types of message types: 1-heartbeat sending (as type 1), 2-heartbeat return (as type 2), 3-traveling wave ranging sending (as type 3), 4-traveling wave speed measurement sending (as type 4);

[0079] This side sends the time stamp. This data is valid for message types 1, 3, and 4. If it is other message types, the time stamp sent by this side is filled with 0;

[0080] The opposite side receives the time stamp. This data is valid for message type 2. If it is other message types, the opposite side receives the time stamp and fills in 0.

[0081] The opposite side sends the time stamp. This data is valid for message type 2. If it is other message types, the opposite side sends the time stamp filled with 0;

[0082] This side wave header frequency 1, this data is valid for message type 3, if it is other message types, this side wave header frequency 1 is filled with 0;

[0083] This side wave header time mark 1, this data is valid for message type 3, if it is other message types, this side wave header time mark 1 is filled with 0; ...

[0085] The local wave header frequency is 10. This data is valid for message type 3. If it is other message types, the local wave header frequency 10 is filled with 0;

[0086] The time stamp of the wave header on this side is 10. This data is valid for message type 3. If it is other message types, the time stamp of the wave header on this side is filled with 0;

[0087] The speed measurement wave frequency on this side. This data is valid for message type 4. If it is other message types, the speed measurement wave frequency on this side is filled with 0;

[0088] The time stamp of the speed measurement wave on this side is valid for message type 4. If it is other message types, the time stamp of the speed measurement wave on this side is filled with 0;

[0089] Frame sequence number, each frame message is incremented by 1 in the order in which it is sent. This data is used to determine whether the message is lost;

[0090] CRC16, this data is the CRC check code, which is used to determine whether the frame message is correct.

[0091] There are 10 wave head frequencies and 10 wave head time scales on this side, corresponding to 10 frequency bands [10kHz, 100kHz), [100kHz, 200kHz), ..., [900kHz, 1000kHz), and each of them searches for the frequency point with the largest amplitude that is greater than the traveling wave threshold value, and records the frequency data groups.

[0092] Figure 3This is the flow chart of FPGA heartbeat signal and fiber communication delay calculation. In order to improve the accuracy of timing time stamp and communication delay calculation, the hard real-time FPGA clock counter is used to mark the time (FPGA built-in clock counter) and calculate the fiber communication delay time without the participation of the ranging CPU. The specific steps of the FPGA of the traveling wave ranging module to achieve high-precision calculation of heartbeat signal and fiber communication delay are as follows:

[0093] A1, the FPGA on this side determines whether the 1-minute timing has expired. If so, it goes to A2, otherwise it goes to A1;

[0094] A2: The FPGA on this side determines whether it is sending data. If so, it goes to A2; otherwise, it goes to A3.

[0095] A3, the FPGA on this side sends a message of type 1, which contains the sending time stamp of this side. The sending time stamp of this side is the 64-bit counter value SCount1 of the FPGA on this side when sending the message of type 1, and then go to A4;

[0096] A4: The FPGA on this side determines whether it has received a message of type 2 sent by the other side. If so, it goes to A5. Otherwise, if it has not received the message within 1 second, it sets the communication abnormal flag and goes to A1.

[0097] A5. The FPGA on this side records the arrival time mark SCount2 of the type 2 message received on this side, and extracts the opposite side receiving time mark and the opposite side sending time mark from the message. The opposite side receiving time mark and the opposite side sending time mark are the 64-bit counter values ​​PCount1 and PCount2 of the opposite side FPGA respectively, and then calculates the optical fiber communication delay time Tdelay:

[0098] Tdelay=[(SCount2-SCount1)-(PCount2-PCount1)] / 2,

[0099] Calculate the deviation value δCnt of the two-end counters (where the two-end counters refer to the FPGA clock counters of the two traveling wave ranging modules):

[0100] δCnt=PCount1-SCount1-Tdelay,

[0101] Finally, Tdelay and δCnt are updated and stored, and the communication normal flag is set and saved to the dual-port RAM on this side, and then go to A1.

[0102] The basic principle is that the FPGA on this side sends a heartbeat message regularly, and after receiving the heartbeat message sent by the local side, the FPGA on the other side also returns a heartbeat message.

[0103] In step A1, the FPGA clock counter on this side determines whether 1 minute has arrived (after starting operation, the FPGA clock counter calculates the time), and the above steps A1-A5 are executed once every 1 minute.

[0104] In step A2, it is determined whether data is being sent, specifically whether the local side is sending data. The data sent may be at least one of message types 1, 3, and 4.

[0105] In step A4, within 1 second refers to within 1 second (including 1 second) from the time when the time stamp is sent by this side.

[0106] In step A5, the message arrival time stamp SCount2 is the arrival time of the message of type 2 recorded by the FPGA clock counter on this side, the opposite side receiving time stamp is the time when the message of type 1 on this side is received recorded by the FPGA clock counter on the opposite side, and the opposite side sending time stamp is the time when the message of type 2 is sent by the opposite side recorded by the FPGA clock counter on the opposite side.

[0107] Among them, Tdelay, δCnt, communication normal flag, and communication abnormal flag are all stored in the dual-port RAM on this side.

[0108] Figure 4 This is the flow chart of online measurement of traveling wave velocity. In order to improve the accuracy of traveling wave ranging and overcome the influence of line differentiation and aging as well as changes in the operating environment on the traveling wave velocity, an online measurement method is used to measure the traveling wave velocity at different frequencies in real time and generate a traveling wave frequency-velocity relationship table; this online measurement step of traveling wave velocity can be automatically performed every 0.5-30 days. The specific steps are as follows:

[0109] B1, the FPGA on this side initializes the traveling wave frequency ft = 10kHz, and then goes to B2;

[0110] B2, the FPGA on this side sends a pulse wave with a frequency of ft and a duration of 300 μs, and stores the FPGA clock counter value SCountt of the first rising edge (which is used as the time mark of the speed measurement wave on this side), and then goes to B3;

[0111] B3, the FPGA on this side fills the relevant data such as the speed measurement wave frequency Sft=ft on this side and the speed measurement wave time scale SCountt on this side into the type 4 message, and sends it to the traveling wave ranging module on the other side, and then goes to B4;

[0112] B4, the opposite side FPGA reads the opposite side sampling data PValue, increases the opposite side sampling time stamp PCount, and writes the opposite side sampling data group [PCount, PValue] cyclically into the opposite side dual-port RAM; the opposite side FPGA determines whether to start recording according to whether the traveling wave mutation amount is greater than the traveling wave threshold value, and if the recording is started, generates 400μs of traveling wave waveform data (i.e., traveling wave recording data) for 100μs before the start of recording and 300μs after the start of recording;

[0113] The opposite side ranging CPU uses Karenbauer transformation to obtain the traveling wave line mode component from the latest 400μs three-phase current / voltage traveling wave recording data stored in the opposite side dual-port RAM, and then performs Hilbert-Huang Transform (HHT) and differential operation on the line mode component to obtain the relationship between the amplitude and time of the traveling wave line mode components of different frequencies, where PCount is the sampling time corresponding to the opposite side sampling data PValue, and PValue is the traveling wave current / voltage amplitude collected on the opposite side; go to B5;

[0114] B5, the ranging CPU on the other side determines whether it has received the type 4 message on the local side. If so, it goes to B6, otherwise to B5;

[0115] B6. The distance measurement CPU on the other side parses the type 4 message on this side, extracts the speed measurement wave frequency Sft and the speed measurement wave time scale SCountt on this side, and obtains the time scale SCounttcal corresponding to the speed measurement wave frequency Sft on this side through the relationship between the wave frequency and time in step B4. First, calculate the clock counter difference △Cnt1 of the two wave head time scales:

[0116] △Cnt1=SCounttcal-(SCountt-δCnt), where δCnt is the deviation value of the two-end counters obtained in the specific steps of implementing high-precision calculation of heartbeat signal and optical fiber communication delay by FPGA;

[0117] Then calculate the absolute time difference △T1 between the two wave heads:

[0118] △T1=△Cnt1 / Ffpga, where Ffpga is the operating frequency of FPGA (the operating frequencies of the FPGA on this side and the opposite side are equal), which is 100MHz;

[0119] Finally, calculate the traveling wave velocity vt:

[0120] vt = L / △T1, where L is the line length (i.e. the length of the line between the two traveling wave ranging modules);

[0121] Go to B7;

[0122] B7, the distance measurement CPU on the opposite side stores the speed measurement traveling wave frequency Sft and the traveling wave speed vt on the local side into the traveling wave frequency-speed relationship table; go to B8;

[0123] B8. Set the traveling wave frequency ft of the FPGA on this side to 100kHz, 200kHz, 300kHz, 400kHz, 500kHz, 600kHz, 700kHz, 800kHz, and 900kHz respectively, and execute steps B2-B7 for each traveling wave frequency respectively.

[0124] In this article, the traveling wave is a current traveling wave or a voltage traveling wave; usually it is a current traveling wave, in which case the sampled data and amplitude are also the current value.

[0125] In the present invention, the two sides are independent of each other, one side sends out a speed measuring traveling wave, and the other side analyzes and generates a frequency-wave speed table; that is, this side sends out a traveling wave, and the opposite side generates a frequency-wave speed table (see steps B1-B8); similarly, the opposite side sends out a traveling wave, and this side generates a frequency-wave speed table (refer to steps B1-B8 for execution).

[0126] What is stored in step B2 is the counter value SCountt of the FPGA on this side at the first rising edge of the 300 μs pulse wave.

[0127] In step B3, the relevant data includes a frame number.

[0128] When the traveling wave ranging module is started and in use, the AD sampling module realizes real-time sampling of the traveling wave voltage or traveling wave current of the line under the control of FPGA. In step B4, the opposite side sampling data PValue is the instantaneous value of the traveling wave current or the instantaneous value of the traveling wave voltage collected by the opposite side (i.e., the traveling wave current / voltage amplitude collected by the opposite side mentioned above), and the opposite side sampling time mark PCount is the sampling time corresponding to the opposite side sampling data PValue (timed by the opposite side FPGA clock counter); during the real-time sampling process, the opposite side sampling data obtained at different sampling times and the opposite side sampling time mark constitute the opposite side sampling data group.

[0129] In step B4, the opposite side sampling data PValue is collected by the opposite side AD sampling module and sent to the opposite side FPGA, and the opposite side FPGA determines whether to start recording based on whether the traveling wave mutation amount is greater than the traveling wave threshold value. The traveling wave threshold value can be 0.2 times the rated current (for example, the traveling wave threshold value can be 1A), and the rated current refers to the rated current of the FPGAs on both sides, wherein the rated currents of the FPGAs on both sides are equal. The traveling wave threshold value can be sent to the FPGA by the ranging CPU through the dual-port RAM.

[0130] In step B4, the traveling wave mutation refers to the difference between the real-time opposite-side sampling data PValue and the maximum value of the opposite-side sampling data PValue 100μs before the pulse wave with a speed measurement traveling wave frequency of 10kHz on this side is sent. The maximum value of the opposite-side sampling data PValue 100μs before the pulse wave with a speed measurement traveling wave frequency of 10kHz on this side is sent refers to the maximum value of the opposite-side sampling data for 100μs before the FPGA on this side sends the 10kHz speed measurement traveling wave and the line does not contain any fault traveling waves or other traveling waves.

[0131] After the speed measurement traveling wave on this side is issued, when the traveling wave mutation amount corresponding to a certain sampling moment on the opposite side is greater than the traveling wave threshold value (and the premise is that the traveling wave mutation amounts at the previous sampling moments are not greater than the traveling wave threshold value), the FPGA on the opposite side starts the recording and generates 400μs of traveling wave waveform data, 100μs before starting the recording and 300μs after starting the recording, and then stores the traveling wave waveform data in the dual-port RAM on the opposite side.

[0132] In step B4, Karenbauer transform, Hilbert-Huang transform and differential operation are all existing technologies, and are executed with reference to the literature (Zhou Zhitong, et al. A method for fault traveling wave ranging of transmission lines based on frequency selection [J]. Electrical Technology, 2024, 25(2): 31-36). After this side sends out 10kHz, 100kHz, 200kHz, 300kHz, 400kHz, 500kHz, 600kHz, 700kHz, 800kHz, and 900kHz speed measurement traveling waves, the opposite side FPGA records the 400μs three-phase current / voltage traveling wave recording data, and then stores the traveling wave recording data in the opposite side dual-port RAM, and then the opposite side ranging CPU obtains the relationship between the amplitude (current amplitude or voltage amplitude) and time (i.e., wave head time scale) of the line mode components of different frequency traveling waves; specifically, The opposite-side ranging CPU, for frequencies of 10kHz, 100kHz, 200kHz, 300kHz, 400kHz, 500kHz, 600kHz, 700kHz, 800kHz and 900kHz, obtains the current amplitude or voltage amplitude in the 400μs three-phase current / voltage traveling wave recording data corresponding to different frequencies and the opposite-side sampling time mark (as the wave head time mark) corresponding to the current amplitude or voltage amplitude through Karenbauer transform, Hilbert-Huang transform and differential operation.

[0133] In step B5, the opposite FPGA receives the local type 4 message and sends the message to the opposite ranging CPU, which then determines whether the local type 4 message is received.

[0134] In step B6, SCountt and SCounttcal are two wave head time scales. The time scale SCounttcal is obtained according to the relationship between the traveling wave frequency and time and the speed measurement traveling wave frequency Sft on this side. Specifically, the traveling wave frequency with a frequency equal to Sft is searched in the traveling wave frequency and time relationship table, and the wave head time scale corresponding to the traveling wave frequency is determined, and the wave head time scale value is assigned to SCounttcal.

[0135] In step B7, the speed measurement wave frequency Sft on this side includes 10kHz, 100kHz, 200kHz, 300kHz, 400kHz, 500kHz, 600kHz, 700kHz, 800kHz, and 900kHz. For each speed measurement wave frequency Sft on this side, the corresponding traveling wave velocity vt is calculated by step B6 and then stored in the traveling wave frequency-velocity relationship table, which is generated and stored by the distance measurement CPU on the opposite side.

[0136] In step B8, when steps B2-B7 are executed for each traveling wave frequency, the traveling wave mutation amount refers to the difference between the real-time opposite-side sampling data PValue and the maximum value of the opposite-side sampling data PValue 100μs before the pulse wave with a speed measurement traveling wave frequency of 10kHz is sent. In addition, when steps B2-B7 are executed for all traveling wave frequencies (including 10kHz), it is ensured that there is no duplication in the time range corresponding to the 400μs three-phase current / voltage traveling wave recording data, so as to prevent the 400μs three-phase current / voltage traveling wave recording data corresponding to different frequencies from interfering with each other.

[0137] Figure 5 This is the flow chart of the traveling wave ranging calculation. In order to improve the calculation accuracy of the ranging time, the hard real-time FPGA clock counter is used to time-stamp the sampling value and start and stop the traveling wave recording data storage, while the ranging CPU completes the data analysis of the traveling wave recording waveform without strong real-time performance. The ranging CPU and FPGA of the two traveling wave ranging modules work together to achieve high-precision calculation of the traveling wave ranging time. The following steps are executed in real time and continuously after the traveling wave ranging module is started, ensuring that the fault distance can be detected as soon as possible after the line fails. The specific steps are as follows:

[0138] C1, the FPGA on this side reads the sampled data SValue on this side, increases the sampling time stamp SCount on this side, writes the sampled data group [SCount, SValue] on this side cyclically into the dual-port RAM1 area on this side, and goes to C2; SCount is the FPGA counter value (the sampling time corresponding to the sampled data SValue on this side), and SValue is the traveling wave current / voltage amplitude collected on this side;

[0139] C2, when the FPGA on this side determines that the traveling wave mutation amount is greater than the traveling wave threshold value, it starts the traveling wave recording and goes to C3, otherwise it goes to C1;

[0140] C3. In order to better analyze the traveling wave waveform and considering the capacity of the dual-port RAM on this side, the FPGA on this side stores the complete traveling wave waveform data of 100μs before the start of recording and 300μs after the start of recording, a total of 400μs, into the dual-port RAM1 area on this side, stops writing to the dual-port RAM1 area on this side, and switches to writing the traveling wave data (the sampling data SValue on this side and the sampling time mark SCount on this side) cyclically into the dual-port RAM2 area on this side to prevent the traveling wave data just collected from being overwritten, and then goes to C4;

[0141] C4, the local ranging CPU uses Karenbauer transformation to obtain the traveling wave line mode component of the latest 400μs three-phase current traveling wave recording data (i.e., traveling wave waveform data) in the local dual-port RAM1 area, and then performs Hilbert-Huang transformation on the traveling wave line mode component. Transform, HHT) and differential operation to obtain the relationship between the amplitude and time of the traveling wave components of different frequencies; in the range of 10 frequency bands [10kHz, 100kHz), [100kHz, 200kHz), ..., [900kHz, 1000kHz), each frequency point with the maximum amplitude (referring to the current amplitude or voltage amplitude) and greater than the traveling wave threshold value is searched, and the frequency data group [Sfi, SCountSti] on this side is recorded, where i = 1-10, Sfi is the frequency value on this side, and SCountSti is the wave head time mark on this side (for a certain frequency value, the wave head time mark corresponds to the time when the amplitude of the 400μs traveling wave recording data at the frequency value is the maximum point), the wave head time mark of the frequency point with an amplitude less than the traveling wave threshold value is cleared to 0, and go to C5;

[0142] C5, the local ranging CPU fills the local frequency data group and other related data into the type 3 message, and sends it to the other side traveling wave ranging module through the local FPGA, and then goes to C6;

[0143] C6, the ranging CPU on this side determines whether it has received the type 3 message from the other side. If so, it goes to C7. Otherwise, if it still has not received the message within 1 second, it sets the ranging time invalid flag;

[0144] C7. The local ranging CPU parses the opposite type 3 message and obtains the opposite frequency data group [Pfi, PCountSti], where Pfi is the opposite frequency value and PCountSti is the opposite wave head time stamp. The opposite frequency data group [Pfi, PCountSti] is compared with the local frequency data group [Sfi, SCountSti] to obtain the local wave head time stamp SCountSt, the opposite wave head time stamp PCountSt, and the wave head frequency f (the wave head frequency is the local frequency value with the same frequency value, the smallest frequency value, and the wave head time stamp not equal to 0). First, calculate the counter difference △Cnt2 of the two wave head time stamps:

[0145] △Cnt2 = SCountSt-(PCountSt-δCnt), where δCnt is the deviation value of the two-end counters obtained in the specific steps of implementing high-precision calculation of heartbeat signals and optical fiber communication delays by FPGA;

[0146] Then calculate the absolute time difference △T2 between the two wave heads:

[0147] △T2=△Cnt2 / Ffpga; where Ffpga is the operating frequency of FPGA, which is 100MHz;

[0148] Finally, go to C8;

[0149] C8. The ranging CPU on this side looks up the traveling wave speed v that is closest to the wave head frequency from the traveling wave frequency-speed relationship table stored in the ranging CPU on this side according to the wave head frequency f (specifically: first find the traveling wave frequency that is closest to the wave head frequency f in the traveling wave frequency-speed relationship table, and then take the corresponding vt value and assign it to the traveling wave speed v), and calculates the distance x from the fault point to the traveling wave ranging module on this side: x=[L+△T2*v] / 2.

[0150] In the present invention, when a line fails at a certain point in the middle, the fault point will send a very short transient traveling wave to both ends of the line. The ranging modules at both ends detect the traveling wave. The traveling wave emitted by the same fault point propagates in two directions, and the frequency components are the same (and contain multiple frequencies); refer to steps C1-C4 to execute and obtain the frequency data group [Sfi, SCountSti] on this side and the frequency data group [Pfi, PCountSti] on the opposite side, and then refer to steps C5-C8 to calculate the distance from the fault point to the traveling wave ranging module.

[0151] When the traveling wave ranging module is started and in use, the AD sampling module realizes the real-time sampling of the traveling wave voltage or traveling wave current of the line under the control of the FPGA. In step C1, the sampling data SValue on this side is collected by the AD sampling module on this side and sent to the FPGA on this side. The sampling data SValue on this side is the instantaneous value of the traveling wave current or the instantaneous value of the traveling wave voltage collected on this side (that is, the traveling wave current / voltage amplitude collected on this side mentioned above), and the sampling time mark SCount on this side is the sampling time corresponding to the sampling data SValue on this side (timed by the FPGA clock counter on this side); in the real-time sampling process, the sampling data on this side obtained at different sampling times and the sampling time mark on this side constitute the sampling data group on this side.

[0152] In step C2, the FPGA on this side determines whether to start recording based on whether the traveling wave mutation amount is greater than the traveling wave threshold value. The traveling wave threshold value is the same as that in step B4. The traveling wave mutation amount in step C2 refers to the difference between the real-time sampling data SValue on this side and the maximum value of the sampling data PValue on the opposite side 100μs before the pulse wave with a speed measurement traveling wave frequency of 10kHz on this side is sent. The maximum value of the sampling data PValue on the opposite side 100μs before the pulse wave with a speed measurement traveling wave frequency of 10kHz on this side is sent refers to the maximum value of the continuous 100μs sampling data on the opposite side before the FPGA on this side sends the 10kHz speed measurement traveling wave in the aforementioned traveling wave speed measurement step and when the line does not contain any fault traveling waves or other traveling waves.

[0153] When the traveling wave mutation amount corresponding to a certain sampling moment on this side is greater than the traveling wave threshold value (and the premise is that the traveling wave mutation amounts at the previous sampling moments are not greater than the traveling wave threshold value), the FPGA on this side starts recording and generates traveling wave waveform data for a total of 400μs, 100μs before starting recording and 300μs after starting recording, and then stores the traveling wave waveform data in the dual-port RAM1 on this side.

[0154] In step C3, the dual-port RAM on this side is divided into two areas: the dual-port RAM1 area on this side and the dual-port RAM2 area on this side, and the dual-port RAM on the opposite side is also the same. Since the above steps are executed in real time after the traveling wave ranging module is started, the latest 400μs three-phase current traveling wave recording data in the dual-port RAM1 area on this side is analyzed by the ranging CPU on this side to obtain the frequency point and the corresponding wave head time stamp data, and the ranging CPU on this side controls the FPGA on this side to switch back to the dual-port RAM1 on this side to cyclically write the sampling data group [SCount, SValue] on this side. When the recording condition in step C2 is met, but the latest 400μs three-phase current traveling wave recording data in the dual-port RAM1 area on this side has not been analyzed in the ranging CPU on this side to obtain the frequency point and the corresponding wave head time stamp data, the updated 400μs three-phase current traveling wave recording data is stored in the dual-port RAM2 area on this side, and the traveling wave recording data is also analyzed by the ranging CPU on this side to obtain the frequency point and the corresponding wave head time stamp data. In actual use, the local dual-port RAM1 area and the local dual-port RAM2 area are sufficient to cope with the recording conditions in step C2. The latest 400μs three-phase current traveling wave recording data is preferentially stored in the local dual-port RAM1 area.

[0155] In this paper, when the traveling wave data is cyclically written into the dual-port RAM, it has formed the traveling wave waveform data. The recording wave means that the traveling wave waveform data of a certain time range (400 μs) is taken as a whole and analyzed by the ranging CPU.

[0156] In step C4, the traveling wave waveform data itself is waveform data after multiple frequencies are composited. The relationship between the amplitude and time of the traveling wave components of different frequencies (for example, from 1, 2, 3, 4, 5...1000kHz) is obtained through Karenbauer transform, Hilbert-Huang transform and differential operation. The meaning of the amplitude and time in the relationship between the amplitude and time of the traveling wave components of different frequencies is the same as the meaning of the amplitude and time in the relationship between the amplitude and time of the traveling wave components of different frequencies in step B4. The meaning of the traveling wave threshold value in step C4 is the same as that in step C2. Karenbauer transform, Hilbert-Huang transform and differential operation are all prior arts, and are executed with reference to the literature (Zhou Zhitong, et al. A traveling wave fault location method for transmission lines based on frequency selection [J]. Electrical Technology, 2024, 25(2): 31-36).

[0157] The relevant data in step C5 includes the frame number.

[0158] In step C6, since both sides are performing fault ranging at the same time, the opposite side also refers to steps C1-C4 and executes and obtains the opposite side frequency data group [Pfi, PCountSti], and then sends it to the local side. The local FPGA receives the opposite side type 3 message and sends it to the local ranging CPU. The local ranging CPU then determines whether the opposite side type 3 message is received.

[0159] In step C7, the wave head time mark SCountSt on this side, the wave head time mark PCountSt on the opposite side, and the wave head frequency f with the smallest frequency value are selected. The reason is that the data with a small frequency value has a small attenuation, which makes the ranging calculation more accurate. In step C7, equal frequency values ​​refer to that a certain frequency value (i.e., frequency point) of the frequency data group on this side is equal to a certain frequency value (i.e., frequency point) of the frequency data group on the opposite side is equal. Equal frequency values, minimum frequency values, and wave head time marks that are not equal to 0 refer to the smallest frequency value on this side among the equal frequency values ​​in the frequency data group on this side and the frequency data group on the opposite side, and the wave head time mark corresponding to the smallest frequency value on this side is not equal to 0 (the frequency value is the final selected frequency value on this side), and the wave head time mark of the opposite side frequency value equal to the minimum frequency value on this side is also not equal to 0 (the frequency value is the final selected frequency value on the opposite side). The two wave head time marks refer to the wave head time mark SCountSt on this side (which is the wave head time mark corresponding to the frequency value on this side finally selected) and the wave head time mark PCountSt on the opposite side (which is the wave head time mark corresponding to the frequency value on the opposite side finally selected).

[0160] In step C8, L is the length of the line between the two traveling wave ranging modules.

[0161] The above embodiments are only used to illustrate the technical solutions of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation shall fall within the protection scope of the present invention.

Claims

1. A traveling wave ranging module based on online speed measurement, characterized in that: It comprises two traveling wave ranging modules, each of which is composed of a ranging CPU, FPGA, dual-port RAM, SFP single-mode optical module, AD sampling module, PT / CT conversion module, PWM module and COM communication module; the dual-port RAM realizes data exchange between the ranging CPU and FPGA; the SFP single-mode optical module realizes long-distance optical fiber communication between the two traveling wave ranging modules; the AD sampling module realizes traveling wave voltage and current sampling; the PT / CT conversion module realizes traveling wave voltage and current conversion; the PWM module receives a pulse wave of variable frequency from the FPGA, realizes pulse wave conditioning and outputs it to a voltage transformer used as a power supply; the two traveling wave ranging modules are respectively installed in two traveling wave ranging devices or two power distribution terminals; the traveling wave ranging devices or the power distribution terminals provide working power to the traveling wave ranging modules; the two traveling wave ranging devices or the power distribution terminals are installed at both ends of the power line.

2. A traveling wave ranging module based on online speed measurement according to claim 1, characterized in that: The ranging CPU and the dual-port RAM, the FPGA and the dual-port RAM are connected through a 16-bit parallel bus, the ranging CPU and the COM communication module are connected through a full-duplex serial bus, the FPGA and the AD sampling module are connected through a 16-bit parallel bus, the AD sampling module and the PT / CT conversion module are connected through a high-frequency signal line, the FPGA and the SFP single-mode optical module are connected through a full-duplex differential bus, and the FPGA and the PWM module are connected through a high-speed IO port.

3. A traveling wave ranging module based on online speed measurement according to claim 1, characterized in that: The FPGA uses a 100MHz constant temperature crystal oscillator and an AD sampling module with a high sampling rate of GSPS. The FPGA periodically starts the AD sampling module to sample and save the sampled data. The sampling frequency is 100MHz. The ranging CPU uses a quad-core ARM chip with a main frequency of more than 1.2GHz and a computing power of more than 2TOPS.

4. A traveling wave ranging module based on online speed measurement according to claim 1, characterized in that: The optical fiber communication between the two traveling wave ranging modules uses data frames of equal length in a unified format.

5. A traveling wave ranging module based on online speed measurement according to claim 4, characterized in that: The data frame contains the following data: There are 4 types of message types: 1-heartbeat sending, 2-heartbeat return, 3-traveling wave ranging sending, 4-traveling wave speed measurement sending; This side sends the timestamp, which is valid for message types 1, 3, and 4; The opposite side receives the time stamp. This data is valid for message type 2. The opposite side sends the timestamp. This data is valid for message type 2. The frequency of the wave head on this side is 1. This data is valid for message type 3, and other message types are filled with 0; The time mark of the wave head on this side is 1. This data is valid for message type 3, and other message types are filled with 0; ... The frequency of the wave head on this side is 10. This data is valid for message type 3, and other message types are filled with 0; The time mark of the wave head on this side is 10. This data is valid for message type 3, and 0 is filled in for other message types; The speed measurement wave frequency on this side is valid for message type 4; The time stamp of the speed measurement wave on this side is valid for message type 4; Frame sequence number, this data is used to determine whether the message is lost; CRC16, this data is the CRC check code, which is used to determine whether the frame message is correct.

6. A traveling wave ranging method based on online velocity measurement, characterized in that: The calculation of optical fiber communication delay is realized by two FPGAs of traveling wave ranging modules. The specific steps are as follows: A1, the FPGA on this side determines whether the 1-minute timing has expired. If so, it goes to A2, otherwise it goes to A1; A2: The FPGA on this side determines whether it is sending data. If so, it goes to A2; otherwise, it goes to A3. A3, the FPGA on this side sends a message of type 1, which contains the time stamp of the sending on this side. The time stamp of the sending on this side is the 64-bit counter value SCount1 of the FPGA on this side, and then goes to A4; A4: The FPGA on this side determines whether it has received a message of type 2 sent by the other side. If so, it goes to A5. Otherwise, if it has not received the message within 1 second, it sets the communication abnormal flag and goes to A1. A5. The FPGA on this side records the arrival time mark SCount2 of the type 2 message received on this side, and extracts the opposite side receiving time mark and the opposite side sending time mark from the message. The opposite side receiving time mark and the opposite side sending time mark are the 64-bit counter values ​​PCount1 and PCount2 of the opposite side FPGA respectively, and then calculates the optical fiber communication delay time Tdelay: Tdelay=[(SCount2-SCount1)-(PCount2-PCount1)] / 2, Calculate the deviation value δCnt of the counters at both ends: δCnt=PCount1-SCount1-Tdelay, Finally, Tdelay and δCnt are updated and stored, and the communication normal flag is set and saved to the dual-port RAM on this side, and then go to A1.

7. A traveling wave ranging method based on online velocity measurement according to claim 6, characterized in that: An online measurement method is used to measure the traveling wave velocity at different frequencies in real time, and a traveling wave frequency-velocity relationship table is generated.

8. The traveling wave ranging method based on online velocity measurement according to claim 7, characterized in that: The specific steps for generating the traveling wave frequency-speed relationship table are as follows: B1, the FPGA on this side initializes the traveling wave frequency ft = 10kHz, and then goes to B2; B2, the FPGA on this side sends a pulse wave with a frequency of ft and a duration of 300 μs, and stores the FPGA clock counter value of the first rising edge as the speed measurement wave time mark SCountt on this side, and then goes to B3; B3, the FPGA on this side fills the speed measurement wave frequency Sft=ft and the speed measurement wave time scale SCountt on this side into the type 4 message, and sends it to the traveling wave ranging module on the other side, and then goes to B4; B4, the opposite side FPGA reads the opposite side sampling data PValue, increases the opposite side sampling time stamp PCount, and writes the opposite side sampling data group [PCount, PValue] cyclically into the opposite side dual-port RAM; the opposite side FPGA determines whether to start recording based on whether the traveling wave mutation amount is greater than the traveling wave threshold value. If the recording is started, it generates 400μs of traveling wave waveform data, 100μs before the start of recording and 300μs after the start of recording; The opposite side ranging CPU uses Karenbauer transformation to obtain the traveling wave line mode component from the latest 400μs three-phase current / voltage traveling wave recording data stored in the opposite side dual-port RAM, and then performs Hilbert-Huang Transform (HHT) and differential operation on the line mode component to obtain the relationship between the amplitude and time of the traveling wave line mode components of different frequencies, where PCount is the sampling time corresponding to the opposite side sampling data PValue, and PValue is the traveling wave current / voltage amplitude collected on the opposite side; go to B5; B5, the ranging CPU on the other side determines whether it has received the type 4 message on the local side. If so, it goes to B6, otherwise to B5; B6. The distance measurement CPU on the other side parses the type 4 message on this side, extracts the speed measurement wave frequency Sft and the speed measurement wave time scale SCountt on this side, and obtains the time scale SCounttcal corresponding to the speed measurement wave frequency Sft on this side through the relationship between the wave frequency and time in step B4. First, calculate the clock counter difference △Cnt1 of the two wave head time scales: △Cnt1=SCounttcal-(SCountt-δCnt), where δCnt is the deviation value of the two-end counters calculated in claim 6; Then calculate the absolute time difference △T1 between the two wave heads: △T1=△Cnt1 / Ffpga, where Ffpga is the operating frequency of FPGA, which is 100MHz; Finally, calculate the traveling wave velocity vt: vt=L / △T1, where L is the line length; Go to B7; B7, the distance measurement CPU on the opposite side stores the speed measurement traveling wave frequency Sft and the traveling wave speed vt on the local side into the traveling wave frequency-speed relationship table; go to B8; B8. Set the traveling wave frequency ft of the FPGA on this side to 100kHz, 200kHz, 300kHz, 400kHz, 500kHz, 600kHz, 700kHz, 800kHz, and 900kHz respectively, and execute steps B2-B7 for each traveling wave frequency respectively.

9. The traveling wave ranging method based on online velocity measurement according to claim 6, characterized in that: The ranging CPU and FPGA of the two traveling wave ranging modules work together to calculate the traveling wave ranging time.

10. A traveling wave ranging method based on online velocity measurement according to claim 9, characterized in that: The specific steps of traveling wave ranging time calculation are as follows: C1, the FPGA on this side reads the sampling data SValue on this side, increases the sampling time stamp SCount on this side, writes the sampling data group [SCount, SValue] on this side cyclically into the dual-port RAM1 area on this side, and then goes to C2; C2: When the FPGA on this side determines that the traveling wave mutation amount is greater than the traveling wave threshold value, it starts the traveling wave recording and goes to C3, otherwise it goes to C1; C3, the FPGA on this side stores the complete traveling wave waveform data of 400μs, 100μs before the start of recording and 300μs after the start, into the dual-port RAM1 area, stops writing to the dual-port RAM1 area on this side, and switches to writing the traveling wave data cyclically into the dual-port RAM2 area on this side, and goes to C4; C4, the local ranging CPU uses Karenbauer transformation to obtain the traveling wave line mode component from the latest 400μs three-phase current traveling wave recording data in the dual-port RAM1 area on this side, and then obtains the relationship between the amplitude and time of the traveling wave components of different frequencies after Hilbert-Huang Transform (HHT) and differential operation on the traveling wave line mode component; searches for the frequency point with the largest amplitude and greater than the traveling wave threshold value in the range of 10 frequency bands [10kHz, 100kHz), [100kHz, 200kHz), ..., [900kHz, 1000kHz), and records the local frequency data group [Sfi, SCountSti], where i = 1-10, Sfi is the local frequency value, SCountSti is the local wave head time mark, and the wave head time mark of the frequency point with an amplitude less than the traveling wave threshold value is cleared to 0, and then goes to C5; C5, the ranging CPU on this side fills the data of the frequency data group on this side into the type 3 message, and sends it to the traveling wave ranging module on the other side through the FPGA, and then goes to C6; C6, the ranging CPU on this side determines whether it has received the type 3 message from the other side. If so, it goes to C7. Otherwise, if it still has not received the message within 1 second, it sets the ranging time invalid flag; C7. The local ranging CPU parses the opposite type 3 message and obtains the opposite frequency data group [Pfi, PCountSti], and compares it with the local frequency data group [Sfi, SCountSti] to obtain the local wave head time mark SCountSt, the opposite wave head time mark PCountSt, and the wave head frequency f, which have equal frequency values, the smallest frequency value, and wave head time marks that are not equal to 0. First calculate the counter difference △Cnt2 of the two wave head time marks: △Cnt2=SCountSt-(PCountSt-δCnt), where δCnt is the deviation value of the two-end counters calculated in claim 6; Then calculate the absolute time difference △T2 between the two wave heads: △T2=△Cnt2 / Ffpga; where Ffpga is the operating frequency of FPGA, which is 100MHz; Finally, go to C8; C8. The local ranging CPU looks up the closest traveling wave speed v from the traveling wave frequency-speed relationship table based on the wave head frequency f, and calculates the distance x from the fault point to the local traveling wave ranging module: x=[L+△T2*v] / 2.

Images