Traveling wave based power cable arbitrary location length measurement device and measurement method

Abstract

The application discloses a kind of power cable arbitrary position length measurement methods based on travelling wave, utilize cable line and earth constitutes distribution parameter, when high frequency travelling wave is transmitted in cable line along earth, and measurement unit is installed at the beginning and end of cable line and any measuring point;The first end unit injects high-frequency high-voltage pulse signal to cable line, after detecting this signal, the end unit injects reverse high-frequency high-voltage pulse signal to cable line after logic combination;2 high-frequency pulse signals are transmitted in cable line to reach each measuring point, the time difference measured using the first end measurement unit and measuring point measurement unit, multiplied by wave velocity, the length of any point of cable line can be measured.The application can measure the distance between the arbitrary point of cable line and the forward signal injection and collection unit, through the movement of travelling wave collection terminal, the effect of measuring the length of any point of cable line can be realized, the work efficiency of power operation and maintenance personnel and power supply reliability are improved, manpower and material resources are saved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of cable fault detection, in particular to a power cable arbitrary position length measurement device and method based on traveling wave. BACKGROUND

[0002] High-voltage power cables are usually buried, in cable trenches and cable sandwiched ways, and it is impossible to completely straighten and exist winding phenomenon during the burying process. The existing measuring equipment can measure the full length of the cable, but cannot measure the length of any point of the cable, which leads to that when a fault occurs at a certain point of the cable, the distance of the fault point can be calculated, but the exact position of the fault point cannot be located, so the specific position of the fault point cannot be found by querying the cable geographic information.

[0003] At present, the methods of cable length and fault point positioning equipment are: bridge method, acoustic magnetic synchronous method, oscillating wave method and capacitance current measurement method.

[0004] The bridge method measures the direct current resistance of the cable core by using a double-arm bridge. According to the proportional relationship between the cable length and the resistance, the fault point is calculated according to the original technical data of the cable. The full length of the cable can be measured, but the fault point cannot be accurately located.

[0005] The acoustic magnetic synchronous method uses continuous low-frequency signals of a specific frequency to transmit along the line. There is a discharge sound at the fault point. A specially designed precise point instrument is used to listen to the discharge sound along the line. It not only consumes time and effort, but also cannot directly identify and find the fault point through the human ear when passing through some direct buried lines and high resistance faults.

[0006] When the cable oscillating wave test is performed, the distance of the fault point from the measurement point can be measured. When there is a problem with the cable body and the fault point is not broken through, there is no obvious fault mark at the fault point, and the specific position of the fault point cannot be found by querying the cable geographic information.

[0007] Capacitance current measurement method: when the cable is in normal operation, there is a uniform distribution of capacitance between the core wires and the ground. The capacitance and the cable length are in linear proportional relationship. According to this principle, the measurement of the cable core wire breakage fault is very accurate, but it is not accurate for other fault types, and the fault point cannot be accurately located.

[0008] In summary, in order to quickly and accurately find the exact position of the fault point, save manpower and material resources, and avoid unnecessary cable cutting, it is necessary to measure the distance of any point of the cable path from the measurement end. Therefore, a new method is needed to measure the length of any point of the buried cable. SUMMARY

[0009] In order to solve the above technical problems, the application provides a power cable length measuring device based on traveling wave and having simple structure and high measuring accuracy, and a power cable length measuring method based on traveling wave and having high measuring efficiency.

[0010] The technical scheme for solving the above technical problems is: a power cable length measuring device based on traveling wave, comprising:

[0011] A forward signal injection and collection unit is arranged at the cable head end, and is used for injecting a forward high-voltage traveling wave signal with a set pulse width into the cable, and calculating a first time difference between the injection of the forward high-voltage traveling wave signal and the detection of a reverse high-voltage traveling wave signal injected at the cable tail end, and then sending the first time difference to a traveling wave collection and calculation terminal by using a communication DTU; the forward signal injection and collection unit comprises a first signal isolation amplification and filter steepening circuit, a first signal detection circuit, a first time sequence combination circuit, a first high-voltage pulse output module, and a first time calibration circuit.

[0012] A reverse signal injection and collection unit is arranged at the cable tail end, and is used for injecting a reverse high-voltage traveling wave signal into the cable after detecting the forward high-voltage traveling wave signal injected at the cable head end; the reverse signal injection and collection unit comprises a second signal isolation amplification and filter steepening circuit, a second signal detection circuit, a second time sequence combination circuit, and a second high-voltage pulse output module.

[0013] A traveling wave collection and calculation terminal is arranged at any monitoring point of the cable, and is used for collecting the time when the forward high-voltage traveling wave signal and the reverse high-voltage traveling wave signal arrive at the monitoring point and calculating a second time difference between the two, and then calculating the length from the forward signal injection and collection unit to the traveling wave collection and calculation terminal based on the first time difference and the second time difference, by using a traveling wave single-end positioning algorithm and in combination with the propagation speed of the traveling wave in the cable; the traveling wave collection and calculation terminal comprises a third signal isolation amplification and filter steepening circuit, a third signal detection circuit, a third MCU processing module, and a second time calibration circuit.

[0014] The forward signal injection and collection unit further comprises a first MCU processing module, a first voltage-boosting energy storage module, a first lithium battery power supply circuit and a first communication module; the first lithium battery power supply circuit provides working power supply for the forward signal injection and collection unit; the input end of the first signal isolation amplification and filtering steepening circuit is connected with the output end of the first high-voltage pulse output module; the output end of the first signal isolation amplification and filtering steepening circuit is connected with the first MCU processing module through the first signal detection circuit; the first MCU processing module is connected with the input end of the first time calibration circuit and the first time sequence combination circuit respectively; the first MCU processing module communicates wirelessly with the traveling wave collection and calculation terminal through the first communication module; the first lithium battery power supply circuit is connected with the first high-voltage pulse output module through the first voltage-boosting energy storage module; and the input end of the first high-voltage pulse output module is connected with the output end of the first MCU processing module and the first time sequence combination circuit respectively.

[0015] The reverse signal injection and collection unit further comprises a second MCU processing module, a second voltage-boosting energy storage module and a second lithium battery power supply circuit; the second lithium battery power supply circuit provides working power supply for the reverse signal injection and collection unit; the input end of the second signal isolation amplification and filtering steepening circuit is connected with the output end of the second high-voltage pulse output module; the output end of the second signal isolation amplification and filtering steepening circuit is connected with the second MCU processing module through the second signal detection circuit; the second MCU processing module is connected with the input end of the second time sequence combination circuit; the second lithium battery power supply circuit is connected with the second high-voltage pulse output module through the second voltage-boosting energy storage module; and the input end of the second high-voltage pulse output module is connected with the output end of the second MCU processing module and the second time sequence combination circuit respectively.

[0016] The traveling wave collection and calculation terminal further comprises a third lithium battery power supply circuit, a second communication module and a storage module; the third lithium battery power supply circuit provides working power supply for the traveling wave collection and calculation terminal; the output end of the third signal isolation amplification and filtering steepening circuit is connected with the third MCU processing module through the third signal detection circuit; the third MCU processing module is connected with the second time calibration circuit, the second communication module and the storage module; the third MCU processing module communicates wirelessly with the forward signal injection and collection unit through the second communication module and the first communication unit; and the third MCU processing module is connected with the LCD display screen through the man-machine interface.

[0017] A traveling wave-based power cable arbitrary position length measurement method, comprising the following steps:

[0018] 1) Install forward signal injection and acquisition unit at the head end of the cable line, install reverse signal injection and acquisition unit at the tail end of the cable line, and install traveling wave acquisition and calculation terminal at any measurement point of the cable line;

[0019] 2) The forward signal injection and acquisition unit injects a forward high-voltage traveling wave signal S1 with a set pulse width into the cable line, detects and marks the trigger time T1 of the forward high-voltage traveling wave signal S1;

[0020] 3) The forward high-voltage traveling wave signal S1 is transmitted in the cable line to reach the measurement point, and the traveling wave acquisition and calculation terminal detects and marks the trigger time T2 of the arrival of the forward high-voltage traveling wave signal S1 at the measurement point;

[0021] 4) The forward high-voltage traveling wave signal S1 continues to transmit in the cable line, and the reverse signal injection and acquisition unit injects a reverse high-voltage traveling wave signal S2 into the cable line after receiving the forward high-voltage traveling wave signal S1;

[0022] 5) The reverse high-voltage traveling wave signal S2 is transmitted in the cable line to reach the measurement point, and the traveling wave acquisition and calculation terminal detects and marks the trigger time T4 of the arrival of the reverse high-voltage traveling wave signal S2 at the measurement point, and calculates the time difference Δt2 of the arrival of the forward high-voltage traveling wave signal S1 and the reverse high-voltage traveling wave signal S2 at the traveling wave acquisition and calculation terminal, Δt2 = T4 - T2;

[0023] 6) The reverse high-voltage traveling wave signal S2 continues to transmit in the cable line, and the forward signal injection and acquisition unit detects and marks the trigger time T3 of the arrival of the reverse high-voltage traveling wave signal S2 at the forward signal injection and acquisition unit after measuring the reverse high-voltage traveling wave signal S2, and calculates the time difference Δt1 of the arrival of the forward high-voltage traveling wave signal S1 and the reverse high-voltage traveling wave signal S2 at the forward signal injection and acquisition unit, Δt1 = T3 - T1, and then sends the time difference Δt1 to the traveling wave acquisition and calculation terminal;

[0024] 7) The traveling wave acquisition and calculation terminal receives the time difference Δt1 sent by the forward signal injection and acquisition unit using 4G or 5G communication DTU technology, and calculates the length value from any point position of the cable line to the head end of the cable line using the formula [(Δt1 - Δt2) x v] / 2; v is the propagation speed of the high-voltage pulse signal in the cable, i.e. the wave speed.

[0025] The above-mentioned power cable length measurement method based on traveling wave is characterized in that the forward high-voltage traveling wave signal S1 and the reverse high-voltage traveling wave signal S2 are both high-voltage pulse signals, and the reverse high-voltage traveling wave signal S2 is a reflected wave of the forward high-voltage traveling wave signal S1.

[0026] The beneficial effects of the present application are as follows:

[0027] 1. The application can measure the distance between any point of the cable and the forward signal injection and acquisition unit, and through the movement of the traveling wave acquisition calculation terminal, the length of any point of the cable can be measured. This solves the defect that the current power cable measurement device and method cannot measure the length of any point of the cable, and can quickly and accurately find the fault point, improves the work efficiency of the power operation and maintenance personnel and the power supply reliability, saves a lot of manpower and material resources, reduces the power outage time, and reduces the labor intensity of the operation and maintenance personnel.

[0028] 2. The application has the advantages of not needing a Beidou, GPS or other time service device, and can operate and measure under various complex working conditions, has high measurement accuracy, fast speed, light weight and is convenient to carry, and has significant social and economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0029] Figure 1 is a schematic diagram of the measurement principle of the application.

[0030] Figure 2 is a work flow chart of the measurement method of the application.

[0031] Figure 3 is a structural block diagram of the forward signal injection and acquisition unit of the application.

[0032] Figure 4 is a structural block diagram of the reverse signal injection and acquisition unit of the application.

[0033] Figure 5 is a structural block diagram of the traveling wave acquisition calculation terminal of the application.

[0034] Figure 6 is a circuit diagram of the signal isolation amplification and filtering steepening circuit of the application.

[0035] Figure 7 is a circuit diagram of the signal detection circuit of the application.

[0036] Figure 8 is a circuit diagram of the time sequence combination circuit of the application.

[0037] Figure 9 is a circuit diagram of the high-voltage pulse output module of the application.

[0038] Figure 10 is a circuit diagram of the time calibration circuit of the application.

[0039] Figure 11 is a circuit principle diagram of the MCU processing module of the application.

[0040] Figure 12 is a circuit diagram of the 500V voltage boosting energy storage circuit of the application.

[0041] Figure 13 is a circuit diagram of the lithium battery and power supply circuit of the present application. DETAILED DESCRIPTION

[0042] The present application will be further described below in conjunction with the accompanying drawings and examples.

[0043] As shown in Figure 1 , a kind of power cable arbitrary position length measurement device based on traveling wave, comprising:

[0044] Forward signal injection and acquisition unit, be arranged in the first end of cable line, i.e. Figure 1 Device A in, for injecting the forward high-voltage traveling wave signal of set pulse width to cable line, and after detecting the reverse high-voltage traveling wave signal injected at the end of cable line, the first time difference of injecting forward high-voltage traveling wave signal and detecting reverse high-voltage traveling wave signal is calculated, then the first time difference is sent to traveling wave acquisition computing terminal using communication DTU;

[0045] Reverse signal injection and acquisition unit, be arranged in the end of cable line, i.e. Figure 1 Device C in, for injecting the reverse high-voltage traveling wave signal to cable line after detecting the forward high-voltage traveling wave signal injected at the first end of cable line;

[0046] Traveling wave acquisition computing terminal, be arranged in the arbitrary monitoring point of cable line, i.e. Figure 1 Device B in, for acquiring the time of forward high-voltage traveling wave signal and reverse high-voltage traveling wave signal reaching monitoring point and calculating the second time difference of two, then based on the first time difference and the second time difference, using traveling wave single-end positioning algorithm, the length of forward signal injection and acquisition unit to traveling wave acquisition computing terminal is calculated in combination with the propagation speed of traveling wave in cable line.

[0047] As shown in Figure 3As shown, the forward signal injection and acquisition unit includes a first signal isolation amplification and filter steepening circuit, a first signal detection circuit, a first timing combination circuit, a first high-voltage pulse output module, a first time calibration circuit, a first MCU processing module, a first voltage boosting energy storage module, a first lithium battery power supply circuit, and a first communication module. The first lithium battery power supply circuit provides working power for the forward signal injection and acquisition unit. The input end of the first signal isolation amplification and filter steepening circuit is connected to the output end of the first high-voltage pulse output module. The output end of the first signal isolation amplification and filter steepening circuit is connected to the first MCU processing module via the first signal detection circuit. The first MCU processing module is connected to the input end of the first communication module, the first time calibration circuit, and the first timing combination circuit, respectively. The first MCU processing module communicates wirelessly with the traveling wave acquisition and calculation terminal through the first communication module. The first lithium battery power supply circuit is connected to the first high-voltage pulse output module via the first voltage boosting energy storage module. The input end of the first high-voltage pulse output module is connected to the output end of the first MCU processing module and the first timing combination circuit, respectively.

[0048] After the forward signal injection and acquisition unit is running, the first signal detection circuit detects that the first voltage boosting energy storage module has boosted 12V to 500V. The first high-voltage pulse output module uses a direct injection traveling wave method to inject a forward high-voltage traveling wave signal S1 into the cable. The first MCU processing module detects S1 and performs logical combination, waiting for the arrival of a second reverse high-voltage traveling wave signal S2. S1 and S2 are transmitted along the cable core. The first signal isolation amplification and filter steepening circuit in the forward signal injection and acquisition unit filters and steepens S1 and S2, which are then collected by the signal detection circuit and sent to the first MCU processing module. The first MCU processing module detects S1 and S2, and through the first time calibration circuit, respectively calibrates the arrival times of the two pulse signals S1 and S2 as T1 and T3, and calculates the first time difference Δt1, Δt1 = T3 - T1. The first MCU processing module sends the first time difference Δt1 to the traveling wave acquisition and calculation terminal through the first communication module.

[0049] As shown in FIG. 6, the forward signal injection and acquisition unit includes a first signal isolation amplification and filter steepening circuit, a first signal detection circuit, a first timing combination circuit, a first high-voltage pulse output module, a first time calibration circuit, a first MCU processing module, a first voltage boosting energy storage module, a first lithium battery power supply circuit, and a first communication module. The first lithium battery power supply circuit provides working power for the forward signal injection and acquisition unit. The input end of the first signal isolation amplification and filter steepening circuit is connected to the output end of the first high-voltage pulse output module. The output end of the first signal isolation amplification and filter steepening circuit is connected to the first MCU processing module via the first signal detection circuit. The first MCU processing module is connected to the input end of the first communication module, the first time calibration circuit, and the first timing combination circuit, respectively. The first MCU processing module communicates wirelessly with the traveling wave acquisition and calculation terminal through the first communication module. The first lithium battery power supply circuit is connected to the first high-voltage pulse output module via the first voltage boosting energy storage module. The input end of the first high-voltage pulse output module is connected to the output end of the first MCU processing module and the first timing combination circuit, respectively. Figure 4As shown, the reverse signal injection and acquisition unit includes a second signal isolation amplification and filter steepening circuit, a second signal detection circuit, a second timing combination circuit, a second high-voltage pulse output module, a second MCU processing module, a second voltage boosting energy storage module, and a second lithium battery power supply circuit. The second lithium battery power supply circuit provides operating power for the reverse signal injection and acquisition unit. The input end of the second signal isolation amplification and filter steepening circuit is connected to the output end of the second high-voltage pulse output module. The output end of the second signal isolation amplification and filter steepening circuit is connected to the second MCU processing module via the second signal detection circuit. The second MCU processing module is connected to the input end of the second timing combination circuit. The second lithium battery power supply circuit is connected to the second high-voltage pulse output module via the second voltage boosting energy storage module. The input end of the second high-voltage pulse output module is connected to the output end of the second MCU processing module and the second timing combination circuit.

[0050] The reverse signal injection and acquisition unit is started. The second signal detection circuit detects that the first voltage boosting energy storage module has boosted 12V to 500V and waits for S1. When S1 is detected, the second high-voltage pulse output module uses a direct injection of traveling wave method to inject S2 in the reverse direction to the cable line.

[0051] As shown in Figure 5 The traveling wave acquisition and calculation terminal includes a third signal isolation amplification and filter steepening circuit, a third signal detection circuit, a third MCU processing module, a second time calibration circuit, a third lithium battery power supply circuit, a second communication module, and a storage module. The third lithium battery power supply circuit provides operating power for the traveling wave acquisition and calculation terminal. The output end of the third signal isolation amplification and filter steepening circuit is connected to the third MCU processing module via the third signal detection circuit. The third MCU processing module is connected to the second time calibration circuit, the second communication module, and the storage module. The third MCU processing module performs wireless communication with the forward signal injection and acquisition unit via the second communication module and the first communication unit. The third MCU processing module is connected to the LCD display screen via the human-machine interface.

[0052] After the power-on initialization of the traveling wave acquisition and calculation terminal is completed, the pulse signals S1 and S2 are waited for. When S1 arrives, the third signal isolation amplification and filtering steepening circuit is amplified, and the edges of the signal are steepened at the same time. The second time calibration circuit calibrates the time T2 when S1 arrives, and continues to wait for the arrival of S2. When S2 arrives, the third signal isolation amplification and filtering steepening circuit is amplified, and the edges of the signal are steepened at the same time. The second time calibration circuit calibrates the time T4 when S2 arrives. The third MCU processing module calculates the second time difference Δt2 of T2 and T4. After the traveling wave acquisition and calculation terminal receives the first time difference Δt1 collected by the forward signal injection and acquisition unit through the second communication module, the time difference Δt of the first time difference Δt1 and the second time difference Δt2 is calculated. Using the traveling wave single-ended positioning algorithm, combined with the propagation speed v of the traveling wave in the cable, the length from the forward signal injection and acquisition unit to the traveling wave acquisition and calculation terminal is calculated, and the calculation formula is: L=(v×Δt) / 2. The third MCU processing module sends the calculation result to the LCD display screen through the human-computer interface for display. The mobile traveling wave acquisition and calculation terminal can measure the length from the forward signal injection and acquisition unit to the traveling wave acquisition and calculation terminal at any point of the cable line. Multiple measurements are taken to take the average value, which can eliminate the influence of random errors and improve the measurement accuracy. For different types of cable lines, the wave speed can be reset through the human-computer interface to measure different types of cable lines.

[0053] It should be noted that the first, second and third in front of the technical features in the forward signal injection and acquisition unit, the reverse signal injection and acquisition unit, and the traveling wave acquisition and calculation terminal are only used to distinguish the belonging of the corresponding technical features, and the structures are the same, such as the first MCU processing module in the forward signal injection and acquisition unit, the second MCU processing module in the reverse signal injection and acquisition unit, and the third MCU processing module in the traveling wave acquisition and calculation terminal. The circuit structure is described as MCU processing module, and the description of other technical features is the same.

[0054] Figure 6 The circuit diagram of the signal isolation amplification and filtering steepening circuit mainly functions to amplify, filter and steepen high-frequency signals. Figure 6 T1 is a high-frequency pulse current transformer, which isolates low-frequency signals and separates strong and weak currents. Since it reacts to dI / dt, it also has a steepening effect. U1 is a voltage follower that improves signal input impedance and load capacity. The signal is amplified by U2, C2 removes the DC component, and passes through the high-frequency component. T2 is a pulse voltage transformer that reacts to dU / dt, further steepens the signal based on the steepening of T1, and Uout outputs the rising edge of the signal below 50ns.

[0055] Figure 7The circuit diagram is for signal detection circuit, detecting the arrival time of high frequency traveling wave signal and whether the energy storage capacitor voltage of 500V voltage boost energy storage circuit reaches 500V. The voltage division circuit of R3, R4 and R5, R6 respectively provides threshold voltage of comparator, U1B reacts positive pulse signal, U1A reacts negative pulse signal, respectively detecting positive pulse signal and negative pulse signal, when the positive and negative pulse exceeds the threshold, the comparator flips, U2A is the quality of the boost square wave signal. Resistance R9 is a 500V voltage sampling resistance, when the voltage reaches 500V, U3B outputs high level, U4A is the quality of the boost signal.

[0056] Figure 8 The circuit diagram is for timing combination circuit, when injecting pulse signal to cable, K1, K2 respectively act, high voltage pulse output module injects high frequency pulse signal to cable. After detecting S1 signal, signal detection circuit starts delay loop, the counter starts counting, when reaching the pre-set time, K1, K2 returns, providing path for S2 signal, ensuring that detection circuit can detect S2 signal.

[0057] As Figure 9 The circuit diagram is for high voltage pulse output module circuit, when not outputting pulse, high voltage energy storage capacitor C1 is in charging state. When injecting pulse signal to cable, relay J2 first acts to connect the loop, Q1 acts, injecting high voltage pulse signal to cable. R2 limits charging current and charging time, R1 controls amplification time with C1.

[0058] As Figure 10 The circuit diagram is for time calibration circuit, Y1 is high precision crystal oscillator, providing high precision clock for logic circuit U1, U1 records the time when signals S1 and S2 arrive, and transmits time data to MCU processing module through data bus, providing basic data for calculation module. Y2 is 200MHz crystal oscillator, providing running clock for U1.

[0059] As Figure 11 The circuit diagram is for MCU processing module, this circuit is the public core processing hardware part of forward signal injection and collection unit, reverse signal injection and collection unit and traveling wave collection calculation terminal, different terminals execute different application programs and run different logic processes. Among them, U1 is core processor, U2 is large capacity SDRAM, and U3 is FLASH.

[0060] As Figure 12The circuit diagram of 500V boost energy storage circuit, this circuit boosts the 12V voltage of lithium battery to 500V, charges the energy storage capacitor C4. Among them, U1, resistor R16, capacitor C2 constitute an oscillation circuit, Q1, Q2 push-pull output, drive Q3, provide high frequency square wave power supply for T1, T1 is a boost transformer. By adjusting R15 and R16, U1 outputs different oscillation frequencies, so that the output voltage of T1 reaches 500V, and the 12V voltage is boosted to 500V, and the 500V voltage charges the high-voltage energy storage capacitor C3. P1 provides power supply for U1 and each drive circuit, R8 provides a discharge circuit for C1 when the equipment is turned off, avoiding accidental electric shock.

[0061] As Figure 13 The circuit diagram of lithium battery and power supply circuit, this circuit provides basic voltage for each functional circuit, and outputs 3.3V, ±5V and 24V from the 12V voltage of lithium battery. Among them, P1 outputs 3.3V as power supply for core processor, logic circuit CPLD and memory chip; P2 outputs 24V as power supply for relay; P3 and P4 together constitute ±5V power supply, providing energy for operational amplifier.

[0062] As Figure 2 A method for measuring the length of an arbitrary position of a power cable based on a traveling wave, comprising the following steps:

[0063] 1) A forward signal injection and collection unit is installed at the head end of the cable, a reverse signal injection and collection unit is installed at the tail end of the cable, and a traveling wave collection and calculation terminal is installed at any measurement point of the cable.

[0064] 2) The forward signal injection and collection unit injects a forward high-voltage traveling wave signal S1 with a set pulse width into the cable, detects and marks the trigger time T1 of the forward high-voltage traveling wave signal S1.

[0065] 3) The forward high-voltage traveling wave signal S1 is transmitted in the cable to the measurement point, and the traveling wave collection and calculation terminal detects and marks the trigger time T2 of the forward high-voltage traveling wave signal S1 arriving at the measurement point.

[0066] 4) The forward high-voltage traveling wave signal S1 continues to transmit in the cable, and the reverse signal injection and collection unit injects a reverse high-voltage traveling wave signal S2 into the cable after receiving the forward high-voltage traveling wave signal S1, both the forward high-voltage traveling wave signal S1 and the reverse high-voltage traveling wave signal S2 are high-voltage pulse signals, and the reverse high-voltage traveling wave signal S2 is an analog reflection wave of the forward high-voltage traveling wave signal S1.

[0067] 5) The reverse high-voltage traveling wave signal S2 is transmitted in the cable line to the measurement point, the traveling wave acquisition and calculation terminal detects and marks the trigger time T4 of the arrival of the reverse high-voltage traveling wave signal S2 at the measurement point, and calculates the time difference Δt2 of the arrival of the forward high-voltage traveling wave signal S1 and the reverse high-voltage traveling wave signal S2 at the traveling wave acquisition and calculation terminal, Δt2 = T4 - T2.

[0068] 6) The reverse high-voltage traveling wave signal S2 continues to transmit in the cable line, and after the forward signal injection and acquisition unit measures the reverse high-voltage traveling wave signal S2, it detects and marks the trigger time T3 of the arrival of the reverse high-voltage traveling wave signal S2 at the forward signal injection and acquisition unit, and calculates the time difference Δt1 of the arrival of the forward high-voltage traveling wave signal S1 and the reverse high-voltage traveling wave signal S2 at the forward signal injection and acquisition unit, Δt1 = T3 - T1, and then sends the time difference Δt1 to the traveling wave acquisition and calculation terminal.

[0069] 7) The traveling wave acquisition and calculation terminal receives the time difference Δt1 sent by the forward signal injection and acquisition unit using 4G or 5G communication DTU technology, and calculates the length value from the arbitrary point position of the cable line to the head end of the cable line using the formula [(Δt1-Δt2)×v] / 2; v is the propagation speed of the high-voltage pulse signal in the cable, i.e. the wave speed.

Claims

1. A traveling wave based power cable arbitrary location length measurement device, characterized by, The application relates to a cable line fault location system based on high-voltage traveling wave, which comprises the following parts: a forward signal injection and collection unit arranged at the cable line head end, which is used for injecting a forward high-voltage traveling wave signal with a set pulse width into the cable line and calculating a first time difference between the injection of the forward high-voltage traveling wave signal and the detection of a reverse high-voltage traveling wave signal injected at the cable line tail end, and then sending the first time difference to a traveling wave collection and calculation terminal through a communication DTU; the forward signal injection and collection unit comprises a first signal isolation amplification and filter steepening circuit, a first signal detection circuit, a first time sequence combination circuit, a first high-voltage pulse output module and a first time calibration circuit; a reverse signal injection and collection unit arranged at the cable line tail end, which is used for injecting a reverse high-voltage traveling wave signal into the cable line after detecting the forward high-voltage traveling wave signal injected at the cable line head end; the reverse signal injection and collection unit comprises a second signal isolation amplification and filter steepening circuit, a second signal detection circuit, a second time sequence combination circuit and a second high-voltage pulse output module; a traveling wave collection and calculation terminal arranged at any monitoring point of the cable line, which is used for collecting the time when the forward high-voltage traveling wave signal and the reverse high-voltage traveling wave signal arrive at the monitoring point and calculating a second time difference between the two, and then calculating the length from the forward signal injection and collection unit to the traveling wave collection and calculation terminal based on the first time difference and the second time difference, the propagation speed of the traveling wave in the cable line and a traveling wave single-end positioning algorithm; the traveling wave collection and calculation terminal comprises a third signal isolation amplification and filter steepening circuit, a third signal detection circuit, a third MCU processing module and a second time calibration circuit.

2. The traveling wave based power cable arbitrary location length measurement apparatus according to claim 1, characterized by: The forward signal injection and collection unit further comprises a first high-voltage pulse output module, a first time calibration circuit, a first MCU processing module, a first voltage boosting and energy storage module, a first lithium battery power supply circuit and a first communication module; the first lithium battery power supply circuit provides working power for the forward signal injection and collection unit; the input end of the first signal isolation amplification and filter steepening circuit is connected with the output end of the first high-voltage pulse output module; the output end of the first signal isolation amplification and filter steepening circuit is connected with the first MCU processing module through the first signal detection circuit; the first MCU processing module is connected with the first communication module, the first time calibration circuit and the input end of the first time sequence combination circuit respectively; the first MCU processing module communicates with the traveling wave collection and calculation terminal wirelessly through the first communication module; The first lithium battery power supply circuit is connected with the first high-voltage pulse output module through the first voltage boosting and energy storage module; the input end of the first high-voltage pulse output module is connected with the output end of the first MCU processing module and the first time sequence combination circuit respectively.

3. The traveling wave based power cable arbitrary location length measurement device of claim 1, wherein: The reverse signal injection and collection unit further comprises a second MCU processing module, a second voltage boosting and energy storage module and a second lithium battery power supply circuit. The second lithium battery power supply circuit provides working power supply for the reverse signal injection and collection unit, the input end of the second signal isolation amplification and filtering steepening circuit is connected with the output end of the second high-voltage pulse output module, the output end of the second signal isolation amplification and filtering steepening circuit is connected with the second MCU processing module through the second signal detection circuit, the second MCU processing module is connected with the input end of the second time sequence combination circuit, the second lithium battery power supply circuit is connected with the second high-voltage pulse output module through the second voltage boosting energy storage module, and the input end of the second high-voltage pulse output module is connected with the output end of the second MCU processing module and the second time sequence combination circuit respectively.

4. The traveling wave based power cable arbitrary location length measurement apparatus as claimed in claim 1, characterized in that: The traveling wave collection and calculation terminal further comprises a third lithium battery power supply circuit, a second communication module and a storage module; the third lithium battery power supply circuit provides working power supply for the traveling wave collection and calculation terminal, the output end of the third signal isolation amplification and filtering steepening circuit is connected with the third MCU processing module through the third signal detection circuit, the third MCU processing module is connected with the second time calibration circuit, the second communication module and the storage module, the third MCU processing module performs wireless communication with the forward signal injection and collection unit through the second communication module and the first communication unit, and the third MCU processing module is connected with the LCD display screen through the man-machine interface.

5. A traveling wave based power cable arbitrary position length measurement method based on the power cable arbitrary position length measurement device according to any one of claims 1 to 4, characterized by, The method comprises the following steps: 1) a forward signal injection and collection unit is installed at the head end of the cable, a reverse signal injection and collection unit is installed at the tail end of the cable, and a traveling wave collection and calculation terminal is installed at any measurement point of the cable; 2) the forward signal injection and collection unit injects a forward high-voltage traveling wave signal S1 with a set pulse width into the cable, detects and marks the trigger time T1 of the forward high-voltage traveling wave signal S1; 3) the forward high-voltage traveling wave signal S1 is transmitted in the cable to the measurement point, the traveling wave collection and calculation terminal detects and marks the trigger time T2 of the arrival of the forward high-voltage traveling wave signal S1 at the measurement point; 4) the forward high-voltage traveling wave signal S1 continues to transmit in the cable, and the reverse signal injection and collection unit injects a reverse high-voltage traveling wave signal S2 into the cable after receiving the forward high-voltage traveling wave signal S1; 5) the reverse high-voltage traveling wave signal S2 is transmitted in the cable to the measurement point, the traveling wave collection and calculation terminal detects and marks the trigger time T4 of the arrival of the reverse high-voltage traveling wave signal S2 at the measurement point, and calculates the time difference Δt2 of the arrival of the forward high-voltage traveling wave signal S1 and the reverse high-voltage traveling wave signal S2 at the traveling wave collection and calculation terminal, Δt2=T4-T2; 6) the reverse high-voltage traveling wave signal S2 continues to transmit in the cable, and the forward signal injection and collection unit detects and marks the trigger time T3 of the arrival of the reverse high-voltage traveling wave signal S2 at the forward signal injection and collection unit after measuring the reverse high-voltage traveling wave signal S2, and calculates the time difference Δt1 of the arrival of the forward high-voltage traveling wave signal S1 and the reverse high-voltage traveling wave signal S2 at the forward signal injection and collection unit, Δt1=T3-T1, and then sends the time difference Δt1 to the traveling wave collection and calculation terminal. 7) The traveling wave acquisition calculation terminal receives the time difference Δt1 transmitted by the forward signal injection and acquisition unit by using 4G or 5G communication DTU technology, and calculates the length value from the cable line position to the cable line head end by using the formula [(Δt1-Δt2)×v] / 2; v is the propagation speed of the high-voltage pulse signal in the cable, that is, the wave speed.

6. The traveling wave based power cable any location length measurement method according to claim 5, characterized in that, The forward high-voltage traveling wave signal S1 and the reverse high-voltage traveling wave signal S2 are both high-voltage pulse signals, and the reverse high-voltage traveling wave signal S2 is a reflected wave of the analog forward high-voltage traveling wave signal S1.

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