Power transmission line grounding fault distance measurement method based on pulse injection method

Abstract

The invention discloses a power transmission line grounding fault distance measurement method based on a pulse injection method. The method comprises the following steps: 1) sleeving a working grounding wire of a power transmission line with an isolation magnetic ring; 2) connecting the output end of the pulse generator with a voltage measurement module in series to form a voltage measurement circuit, and connecting the voltage measurement circuit on the power transmission line in parallel; 3) the pulse generator outputs a pulse voltage, and the pulse voltage is converted into a pulse traveling wave on the power transmission line for propagation; 4) when the pulse traveling wave is propagated to the fault grounding position of the power transmission line, pulse reflection occurs at the fault grounding position, and the generated pulse reflection wave is propagated back to the voltage measurement line; and 5) the voltage measurement module records the arrival time of the pulse reflection wave, and calculates the fault grounding position of the power transmission line according to the traveling wave propagation speed. The isolation magnetic ring is added to prevent pulse injection signals from directly entering the ground. Therefore, the pulse can be measured on the working grounded power transmission line.

Description

Technical Field

[0001] The invention relates to the technical field of electrical testing, and in particular to a method for measuring ground fault distance of a power transmission line based on a pulse injection method. Background Art

[0002] Before a newly built transmission line is put into operation, a series of electrical tests are required to ensure that its electrical performance meets the design requirements and to ensure the safe and stable operation of the power system. The main electrical test items include insulation performance test, conductor resistance test, grounding test, line parameter measurement, etc. During the test, the line needs to be grounded and the grounding wire needs to be hung. However, after the test, there may be some reasons why the grounding wire is not removed, so it is necessary to manually patrol the line to find out whether there is any grounding wire that has not been removed. In addition, there may be some metal wires that are grounded, and these grounding conditions cannot be found in time with the naked eye. Once the line is put into operation, accidents such as line overcurrent and relay protection action will occur.

[0003] Before the transmission line is put into operation, it is necessary to conduct a short-circuit grounding test on the transmission line. The traditional test method is to test the insulation of the transmission line by applying a withstand voltage. However, since the transmission line is very long and there is a working ground at the end of the transmission line, the withstand voltage test will definitely show a line grounding fault. It is impossible to identify the grounding at a certain point in the middle of the line. Summary of the invention

[0004] The object of the present invention is to provide a method for measuring ground fault distance of a power transmission line based on a pulse injection method, comprising the following steps:

[0005] 1) Put the isolation magnetic ring on the working ground wire of the transmission line.

[0006] 2) Connect the output end of the pulse generator in series with the voltage measurement module to form a voltage measurement circuit, and then connect the voltage measurement circuit in parallel to the transmission line.

[0007] 3) The pulse generator outputs a pulse voltage, which is converted into a pulse traveling wave for propagation on the transmission line.

[0008] 4) When the pulse traveling wave propagates to the fault grounding point of the transmission line, pulse reflection occurs at the fault grounding point, and the generated pulse reflection wave propagates back to the voltage measurement line.

[0009] 5) The voltage measurement module records the arrival time of the pulse reflection wave and calculates the location of the fault grounding point of the transmission line based on the propagation speed of the traveling wave.

[0010] Furthermore, the isolation magnetic ring forms an inductance on the working grounding wire of the power transmission line to prevent the pulse traveling wave from being injected into the earth through the working grounding wire.

[0011] Furthermore, the amplitude range of the pulse voltage output by the pulse generator is 1 kV-5 kV.

[0012] Furthermore, the pulse width range of the pulse voltage output by the pulse generator is 100ns-1000ns.

[0013] Furthermore, the frequency range of the pulse voltage output by the pulse generator is 1 Hz-100 Hz.

[0014] Furthermore, the pulse voltage output by the pulse generator is a square wave pulse.

[0015] Furthermore, the measurement range of the voltage measurement module is 1V-5kV.

[0016] Furthermore, the measurement frequency band of the voltage measurement module is DC-10 MHz.

[0017] Furthermore, the inductance value formed by the isolation magnetic ring on the working ground wire of the power transmission line is not less than 10 μH.

[0018] Further, the position of the fault grounding point of the transmission line is as follows:

[0019]

[0020] Where L is the distance from the fault grounding point to the voltage measurement line. 2 is the arrival time of the pulse reflection wave. 0 It is the starting time when the pulse voltage is transformed into a pulse traveling wave and propagates on the transmission line. V is the traveling wave propagation speed.

[0021] The technical effect of the present invention is unquestionable. The present invention proposes a method for measuring and identifying ground faults in power transmission lines based on the pulse injection method. By inserting a magnetic ring in series on the working grounding wire outside the test point of the transmission line to form a large inductance, the high-frequency pulse signal is isolated, thereby ensuring that the pulse signal only propagates to the inside of the line, and according to the time delay of the reflected signal after the line propagation, the ground fault of the transmission line is identified and located. Accurate identification and positioning of ground faults in transmission lines with working grounding is achieved.

[0022] The present invention adds an isolation magnetic ring to prevent the pulse injection signal from directly entering the earth, thereby ensuring that the pulse can be measured on the working grounded transmission line. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a schematic diagram of a method for measuring ground fault location of a transmission line based on a pulse injection method;

[0024] Figure 2 This is the schematic diagram of the high voltage pulse generator circuit;

[0025] Figure 3 Schematic diagram of pulse injection ranging and waveform reflection;

[0026] Figure 4 This is a simulation diagram of the distributed parameters of a transmission line with a length of 100 km;

[0027] Figure 5 Schematic diagram of pulse injection and reflection waveforms for the transmission line simulation model;

[0028] Figure 6 Schematic diagram of the measured pulse injection and reflection waveforms of the transmission line. DETAILED DESCRIPTION

[0029] The present invention is further described below in conjunction with the embodiments, but it should not be understood that the above subject matter of the present invention is limited to the following embodiments. Without departing from the above technical ideas of the present invention, various substitutions and changes are made according to the common technical knowledge and customary means in the art, which should all be included in the protection scope of the present invention.

[0030] Embodiment 1:

[0031] See also Figures 1 to 6 , a method for measuring ground fault location of a power transmission line based on a pulse injection method, comprising the following steps:

[0032] 1) Put the isolation magnetic ring on the working ground wire of the transmission line.

[0033] 2) Connect the output end of the pulse generator in series with the voltage measurement module to form a voltage measurement circuit, and then connect the voltage measurement circuit in parallel to the transmission line.

[0034] 3) The pulse generator outputs a pulse voltage, which is converted into a pulse traveling wave for propagation on the transmission line.

[0035] 4) When the pulse traveling wave propagates to the fault grounding point of the transmission line, pulse reflection occurs at the fault grounding point, and the generated pulse reflection wave propagates back to the voltage measurement line.

[0036] 5) The voltage measurement module records the arrival time of the pulse reflection wave and calculates the location of the fault grounding point of the transmission line based on the propagation speed of the traveling wave.

[0037] Embodiment 2:

[0038] A method for measuring ground fault distance of a power transmission line based on a pulse injection method. The main technical content is shown in Example 1. Furthermore, the isolation magnetic ring forms an inductance on the working grounding wire of the transmission line to prevent the pulse traveling wave from being injected into the earth through the working grounding wire.

[0039] Embodiment 3:

[0040] A method for measuring ground fault distance of a power transmission line based on a pulse injection method. The main technical content is shown in any one of Examples 1 to 2. Furthermore, the amplitude range of the pulse voltage output by the pulse generator is 1kV-5kV.

[0041] Embodiment 4:

[0042] A method for measuring ground fault distance of a power transmission line based on a pulse injection method. The main technical content is shown in any one of embodiments 1 to 3. Furthermore, the pulse width range of the pulse voltage output by the pulse generator is 100ns-1000ns.

[0043] Embodiment 5:

[0044] A method for measuring ground fault distance of a power transmission line based on a pulse injection method. The main technical content is shown in any one of embodiments 1 to 4. Furthermore, the frequency range of the pulse voltage output by the pulse generator is 1Hz-100Hz.

[0045] Embodiment 6:

[0046] A method for measuring ground fault distance in a power transmission line based on a pulse injection method. The main technical content is shown in any one of embodiments 1 to 5. Furthermore, the pulse voltage output by the pulse generator is a square wave pulse.

[0047] Embodiment 7:

[0048] A method for measuring ground fault distance of a power transmission line based on a pulse injection method. The main technical content is shown in any one of embodiments 1 to 6. Furthermore, the measurement range of the voltage measurement module is 1V-5kV.

[0049] Embodiment 8:

[0050] A method for measuring ground fault distance in a power transmission line based on a pulse injection method. The main technical content is shown in any one of embodiments 1 to 7. Furthermore, the measurement frequency band of the voltage measurement module is DC-10 MHz.

[0051] Embodiment 9:

[0052] A method for measuring ground fault distance in a power transmission line based on a pulse injection method. The main technical content is shown in any one of embodiments 1 to 8. Furthermore, the inductance value formed by the isolation magnetic ring on the working ground wire of the transmission line is not less than 10μH.

[0053] Embodiment 10:

[0054] A method for measuring ground fault distance of a power transmission line based on a pulse injection method, the main technical content of which is shown in any one of embodiments 1 to 9. Further, the position of the fault grounding point of the transmission line is as follows:

[0055]

[0056] Where L is the distance from the fault grounding point to the voltage measurement line. 2 is the arrival time of the pulse reflection wave. 0 It is the starting time when the pulse voltage is transformed into a pulse traveling wave and propagates on the transmission line. V is the traveling wave propagation speed.

[0057] Embodiment 11:

[0058] See also Figures 1 to 6 , a method for measuring ground fault location of a power transmission line based on a pulse injection method, comprising the following steps:

[0059] 1) Before the ground fault distance measurement experiment, put the isolation magnetic ring on the working ground wire of the transmission line, such as Figure 1 Shown on the left.

[0060] 2) Connect the output end of the pulse generator in series with the voltage measurement module to form a voltage measurement circuit, and then connect the voltage measurement circuit in parallel to the transmission line.

[0061] 3) The pulse generator outputs a pulse voltage, which is converted into a pulse traveling wave for propagation on the transmission line (T 0 At this moment, since there is an isolation magnetic ring on the left side of the transmission line, the magnetic ring will form a large inductance, isolating the pulse wave and preventing the pulse wave from propagating to the left, that is, it will not be injected into the earth through the working grounding. This ensures that the pulse wave will not decay rapidly due to grounding.

[0062] 4) The pulse wave propagates to the right on the transmission line. When the pulse wave propagates to the fault grounding point of the transmission line, that is, T 1 At this moment, due to the grounding of the line, the wave impedance of the transmission line will drop sharply, and pulse reflection will occur at the fault grounding point. The generated pulse reflection wave will propagate back to the voltage measurement line.

[0063] 5) The voltage measurement module records the arrival time of the pulse reflection wave, i.e. T 2 At that moment, the position of the fault grounding point of the transmission line is calculated based on the traveling wave propagation speed.

[0064] Embodiment 12:

[0065] A method for measuring ground fault distance of a power transmission line based on a pulse injection method. The main technical content is shown in Example 11. Furthermore, the isolation magnetic ring forms an inductance on the working grounding wire of the transmission line to prevent the pulse traveling wave from being injected into the earth through the working grounding wire.

[0066] Embodiment 13:

[0067] A method for measuring ground fault distance of a power transmission line based on a pulse injection method. The main technical content is shown in any one of Examples 11 to 12. Furthermore, the amplitude range of the pulse voltage output by the pulse generator is 1kV-5kV.

[0068] Embodiment 14:

[0069] A method for measuring ground fault distance of a power transmission line based on a pulse injection method. The main technical content is shown in any one of Examples 11 to 13. Furthermore, the pulse width range of the pulse voltage output by the pulse generator is 100ns-1000ns.

[0070] Embodiment 15:

[0071] A method for measuring ground fault distance in a power transmission line based on a pulse injection method. The main technical content is shown in any one of Examples 11 to 14. Furthermore, the frequency range of the pulse voltage output by the pulse generator is 1 Hz-100 Hz.

[0072] Embodiment 16:

[0073] A method for measuring ground fault distance in a power transmission line based on a pulse injection method. The main technical content is shown in any one of Examples 11 to 15. Furthermore, the pulse voltage output by the pulse generator is a square wave pulse.

[0074] Embodiment 17:

[0075] A method for measuring ground fault distance of a power transmission line based on a pulse injection method. The main technical content is shown in any one of Examples 11 to 16. Furthermore, the main structure of the voltage measurement module is a resistor divider, and the measurement range of the voltage measurement module is 1V-5kV.

[0076] Embodiment 18:

[0077] A method for measuring ground fault distance in a power transmission line based on a pulse injection method. The main technical content is shown in any one of Examples 11 to 17. Furthermore, the measurement frequency band of the voltage measurement module is DC-10MHz, so that the pulse injection parameters and the reflected wave parameters can be accurately measured.

[0078] Embodiment 19:

[0079] A method for measuring ground fault distance in a power transmission line based on a pulse injection method, the main technical content of which is shown in any one of embodiments 11 to 18. Furthermore, the inductance value formed by the isolation magnetic ring on the working ground wire of the transmission line is not less than 10μH.

[0080] The isolation magnetic ring is a large-sized magnetic ring, which is placed on the working ground wire of the power transmission line. The inductance value formed is ≥10μH, which can effectively isolate the pulses output by the pulse generator.

[0081] Embodiment 20:

[0082] A method for measuring ground fault distance of a power transmission line based on a pulse injection method, the main technical content of which is shown in any one of embodiments 11 to 19. Further, the position of the fault grounding point of the transmission line is as follows:

[0083]

[0084] Where L is the distance from the fault grounding point to the voltage measurement line. 2 is the arrival time of the pulse reflection wave. 0 It is the starting time when the pulse voltage is transformed into a pulse traveling wave and propagates on the transmission line. V is the traveling wave propagation speed.

[0085] Embodiment 21:

[0086] A method for measuring ground fault distance of a power transmission line based on a pulse injection method, the main technical content of which is shown in any one of Embodiments 11 to 20. Further, the circuit topology of the pulse generator is as follows:

[0087] The positive end of the DC power supply is called terminal A, the negative end is called terminal B, and terminal B is grounded.

[0088] The A terminal is connected to the drain of switch S1, the source of switch S1 is connected to the drain of switch S2, the source of switch S2 is connected to the drain of switch S3, the source of switch S3 is connected to the drain of switch S4, and the source of switch S4 is connected to the B terminal.

[0089] The drain of the switch S1 is connected to the resistor R11 and the capacitor C11 in sequence, and then connected to the source of the switch S1 .

[0090] The drain of the switch S1 is connected to the resistor R12 and then to the source of the switch S1 .

[0091] The drain of the switch S2 is sequentially connected to the resistor R21 and the capacitor C21 and then connected to the source of the switch S2.

[0092] The drain of the switch S2 is connected to the resistor R22 and then to the source of the switch S2.

[0093] The drain of the switch S3 is sequentially connected to the resistor R31 and the capacitor C31 and then connected to the source of the switch S3 .

[0094] The drain of the switch S3 is connected to the resistor R32 and then to the source of the switch S3 .

[0095] The drain of the switch S4 is sequentially connected to the resistor R41 and the capacitor C41 and then connected to the source of the switch S4 .

[0096] The drain of the switch S4 is connected to the resistor R42 and then to the source of the switch S4 .

[0097] The drain of the switch S3 and the source of the switch S4 serve as output terminals of the pulse generator to output a pulse signal.

[0098] The switch S1 , switch S2 , switch S3 , and switch S4 are all MOSFET switches.

[0099] The voltage amplitude range of the DC output of the power supply is 0-5000V.

[0100] The pulse amplitude range of the pulse generator output is 0-5kV.

[0101] Embodiment 22:

[0102] A method for measuring ground fault distance in a power transmission line based on a pulse injection method, the main technical content of which is shown in any one of embodiments 11 to 21. Furthermore, the voltage measurement module includes a resistor divider.

[0103] Embodiment 23:

[0104] See also Figures 1 to 6 , a method for measuring ground fault location of transmission lines based on pulse injection method, the main technical contents include:

[0105] The device comprises a high-voltage pulse generator, a voltage measuring module and an isolation magnetic ring.

[0106] The pulse parameters that the pulse generator can output are: square wave pulse with amplitude of 1kV-5kV, pulse width of 100ns-1000ns, and frequency of 1-100Hz.

[0107] The main structure of the voltage measurement module is a resistor divider with a measurement range of 1V-5kV and a measurement frequency band of DC-10MHz, so that pulse injection parameters and reflected wave parameters can be accurately measured.

[0108] The isolation magnetic ring is a large-sized magnetic ring, which is placed on the working ground wire of the power transmission line. The inductance value formed is ≥10μH, which can effectively isolate the pulses output by the pulse generator.

[0109] The main innovation of this patent is to add an isolation magnetic ring to place the pulse injection signal directly into the ground, thereby ensuring that the pulse can be measured on the working grounded transmission line.

[0110] Its basic working principle is (see Figure 1 )

[0111] 1) Before the ground fault distance measurement experiment, put the isolation magnetic ring on the working ground wire (such as Figure 1 shown on the left).

[0112] 2) Connect the output end of the pulse generator to the transmission line, and connect the voltage measurement module between the transmission line and the ground at the same position.

[0113] 3) The high-voltage pulse generator outputs high-voltage pulses, which are injected into the transmission line (T 0 time).

[0114] 4) The pulse wave will propagate along the transmission line, but since there is an isolation magnetic ring on the left side of the transmission line, the magnetic ring will form a large inductance, isolating the pulse wave and preventing it from propagating to the left, that is, it will not be injected into the earth through the working grounding. This ensures that the pulse wave will not decay rapidly due to grounding.

[0115] 5) The pulse wave propagates to the right on the transmission line until it reaches the fault grounding point, i.e. T 1 At this moment, due to the grounding of the line, the wave impedance of the transmission line will drop sharply, so reflection will occur at the fault grounding point.

[0116] 6) The pulse reflection wave will propagate to the left and continue to propagate to the voltage measurement module, that is, T 2 At this moment, the arrival time of the reflected wave can be measured.

[0117] 7) Record the time T when it reaches the measurement module 2 , according to the traveling wave propagation velocity V, the distance of the fault grounding can be obtained.

[0118] The pulse generator circuit diagram is as follows Figure 2 As shown in the figure, the high voltage DC power supply parameter is adjustable from 0 to 5000V.

[0119] Switches S1, S2, S3, and S4 are all MOSFET switches, and the withstand voltage of a single switch is 3.3kV. In order to output a 5kV pulse voltage, two switches are used in series. As shown in the figure above, switches S1 and S2 work in series, and switches S3 and S4 work in series. Thus, 0-5kV adjustable high-voltage pulses are output.

[0120] The principle diagram of pulse injection ranging is as follows Figure 3 shown.

[0121] The square wave pulse is injected, encounters a grounding point on the line, is reflected, and then the reflected wave is transmitted back to the measurement point, so that the time is calculated to obtain the position of the grounding point.

[0122] Generally, the Z of a single-conductor overhead transmission line is 500Ω. The wave impedance of a split conductor will decrease due to the increase in capacitance and decrease in inductance, that is, Z≈300Ω. The simulated wave impedance can be 300Ω.

[0123] For overhead transmission lines, ε and μ are usually approximately 1, which means that the propagation speed of traveling waves in overhead transmission lines is equivalent to the speed of light in a vacuum, that is, 3×108m / s.

[0124] According to relevant data, the line parameters are L as 1.27mH / km and C as 0.014uF / km.

[0125] When the total length of the line L is 100 km, the total inductance of the line can be approximately expressed as L*L0, and the capacitance to ground is L*C0.

[0126] The circuit model established is as follows Figure 4 As shown in the simulation diagram of a 100km transmission line, the pulse is 10us and the single pulse voltage amplitude is 300V.

[0127] A ground fault is set at 55km of the line, and the simulation waveform is as follows Figure 5 As shown, the time for reflection is 370μs, according to the formula The distance to the fault grounding point can be calculated.

[0128] Where V is the speed of traveling wave propagation, which is the speed of light, 300,000 km / s.

[0129] Therefore, L=55km is calculated, which is consistent with the distance of the fault grounding setting, thus verifying the feasibility of this method.

[0130] Embodiment 24:

[0131] A method for measuring ground fault distance of a power transmission line based on a pulse injection method. The main technical content is shown in Example 23. Further, in order to verify the principle of the above technology, a fault grounding test is carried out on a certain transmission line. The test wiring is Figure 1 The fault grounding point is 3 km away. The pulse injection and reflection waveforms are as follows: Figure 6 shown.

[0132] from Figure 6 It can be seen that in T 0 At this moment, a 2kV, 1μs high voltage pulse is injected. After 20μs (T 2 At this moment, the reflected wave is obtained by the voltage measurement module, and the time difference is T 2 -T 0 =20μs.

[0133] By formula The distance to the fault grounding point can be calculated.

[0134] Where V is the speed of traveling wave propagation, which is the speed of light, 300,000 km / s.

[0135] Therefore, L=3km is calculated, which is consistent with the distance of the fault grounding setting, thus verifying the feasibility of this method.

Claims

1. A method for measuring ground fault location of a power transmission line based on a pulse injection method, characterized in that: The following steps are involved: 1) Put the isolation magnetic ring on the working ground wire of the transmission line; 2) Connect the output end of the pulse generator in series with the voltage measurement module to form a voltage measurement circuit, and then connect the voltage measurement circuit in parallel to the transmission line. 3) The pulse generator outputs a pulse voltage, which is converted into a pulse traveling wave for propagation on the transmission line; 4) When the pulse traveling wave propagates to the fault grounding point of the transmission line, pulse reflection occurs at the fault grounding point, and the generated pulse reflection wave propagates back to the voltage measurement line. 5) The voltage measurement module records the arrival time of the pulse reflection wave and calculates the location of the fault grounding point of the transmission line based on the propagation speed of the traveling wave.

2. A method for measuring ground fault location of a power transmission line based on a pulse injection method according to claim 1, characterized in that: The isolation magnetic ring forms an inductance on the working grounding wire of the power transmission line to prevent the pulse traveling wave from being injected into the earth through the working grounding wire.

3. A method for measuring ground fault location of a power transmission line based on a pulse injection method according to claim 1, characterized in that: The amplitude range of the pulse voltage output by the pulse generator is 1 kV-5 kV.

4. A method for measuring ground fault location of a power transmission line based on a pulse injection method according to claim 1, characterized in that: The pulse width range of the pulse voltage output by the pulse generator is 100ns-1000ns.

5. A method for measuring ground fault location of a power transmission line based on a pulse injection method according to claim 1, characterized in that: The frequency range of the pulse voltage output by the pulse generator is 1 Hz-100 Hz.

6. A method for measuring ground fault location of a power transmission line based on a pulse injection method according to claim 1, characterized in that: The pulse voltage output by the pulse generator is a square wave pulse.

7. A method for measuring ground fault location of a power transmission line based on a pulse injection method according to claim 1, characterized in that: The measurement range of the voltage measurement module is 1V-5kV.

8. A method for measuring ground fault location of a power transmission line based on a pulse injection method according to claim 1, characterized in that: The measurement frequency band of the voltage measurement module is DC-10 MHz.

9. A method for measuring ground fault location of a power transmission line based on a pulse injection method according to claim 1, characterized in that: The inductance value formed by the isolation magnetic ring on the working grounding wire of the power transmission line is not less than 10 μH.

10. A method for measuring ground fault location of a power transmission line based on a pulse injection method according to claim 1, characterized in that: The location of the fault grounding point of the transmission line is as follows: Where L is the distance from the fault grounding point to the voltage measurement line; T2 is the arrival time of the pulse reflection wave; T0 is the starting time when the pulse voltage is transformed into a pulse traveling wave for propagation on the transmission line; V is the traveling wave propagation speed.

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