System and method for measuring parameters of a distribution network line and locating faults based on signal injection

Abstract

The system and method for measuring parameters of distribution network line and locating faults based on signal injection, high-frequency pulse signal is injected into the front-end coupling capacitor circuit, and then flows through the distribution line and the end coupling capacitor circuit in turn; the front-end and end coupling capacitor circuits transmit the detected high-frequency pulse signal to the front-end and end ranging feeder terminals, and the front-end and end ranging feeder terminals send the high-frequency pulse signal marked with a time stamp to the ranging master station respectively; the ranging master station calculates the actual wave speed of the line; the front-end and end coupling capacitor circuits transmit the detected fault traveling wave signal to the front-end and end ranging feeder terminals, and the front-end and end ranging feeder terminals send the fault traveling wave signal marked with a time stamp to the ranging master station respectively; the ranging master station calculates the fault distance. The actual wave speed of the line and the fault distance are output results of the system for measuring parameters of distribution network line and locating faults. The wave speed of the line is accurately measured, thereby solving the problem of ranging error caused by inaccurate wave speed.

Description

Technical Field

[0001] This invention relates to the field of power distribution line parameter measurement technology, and in particular to a system and method for measuring power distribution line wave velocity and locating faults based on signal injection. Background Technology

[0002] Distribution networks are characterized by a large number of lines and complex structures, making them susceptible to faults and outages caused by lightning, strong winds, and trees during actual operation. Fault locations are often concealed, making on-site location difficult. Failure to locate the fault precisely and restore power quickly can trigger a chain reaction, such as fires and prolonged power outages. Current technologies for fault location in distribution networks generally rely on distribution automation systems and fault indicators. However, limitations in the terminal deployment and monitoring range of distribution automation systems restrict this to kilometer-level fault location, failing to meet the needs of refined operation and maintenance management of distribution networks.

[0003] The traveling wave method, a technique for precise location of line faults, utilizes the time difference between the arrival of the traveling wave at the fault point and the measurement point, along with the wave velocity, to determine fault location. Line length and wave velocity are essential parameters in traveling wave fault location technology. The actual wave velocity is affected by factors such as frequent variations in line parameters, geographical environment, and climate. Furthermore, the line length is usually referenced to the horizontal distance between two towers, neglecting line sag and changes caused by thermal expansion and contraction. This length error can be equivalently represented as a wave velocity error in calculations. Therefore, using a fixed approximate speed of light or an empirical value for wave velocity calculation can significantly impact the accuracy of fault location. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a distribution network line parameter measurement and fault location system and method based on signal injection, which accurately measures line wave velocity, thereby solving the problem of ranging errors caused by inaccurate wave velocity.

[0005] The present invention adopts the following technical solution.

[0006] This invention proposes a distribution network line parameter measurement and fault location system based on signal injection. The system includes: a head-end coupling capacitor circuit installed at the head end of the distribution network line, an end-end coupling capacitor circuit installed at the end of the distribution network line, a head-end ranging feeder terminal, an end-end ranging feeder terminal, and a ranging master station.

[0007] When measuring line parameters, a high-frequency pulse signal is injected into the first-end coupling capacitor circuit and then flows sequentially through the distribution line and the last-end coupling capacitor circuit. The first-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the first-end ranging feeder terminal, and the last-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the last-end ranging feeder terminal. The first-end and last-end ranging feeder terminals respectively send the time-stamped high-frequency pulse signal to the ranging master station. The ranging master station calculates the actual wave velocity of the line.

[0008] When a line fault occurs, the first-end coupling capacitor circuit transmits the detected fault traveling wave signal to the first-end ranging feeder terminal, and the last-end coupling capacitor circuit transmits the detected fault traveling wave signal to the last-end ranging feeder terminal; the first-end ranging feeder terminal and the last-end ranging feeder terminal respectively send the time-stamped fault traveling wave signal to the ranging master station; the ranging master station calculates the fault distance based on the actual wave velocity of the line;

[0009] The actual wave velocity and fault distance of the line are used as the output results of the distribution network line parameter measurement and fault location system.

[0010] Both the first-end coupling capacitor circuit and the last-end coupling capacitor circuit include: a three-phase capacitor, a three-phase through-hole sensor, a three-phase inductor, and a three-phase switch; in each phase, one end of the capacitor is connected to the distribution network line, and the other end of the capacitor is connected to one end of the inductor and one end of the switch. The other end of the inductor is grounded, and the other end of the switch is grounded. The through-hole sensor is connected in series on the connection line between the capacitor and the inductor.

[0011] One end of any two phase switches in the first-end coupling capacitor circuit is connected to a pulse signal generator, which is used to output a high-frequency pulse signal with a set frequency and amplitude.

[0012] The through-core sensor in the first-end coupling capacitor circuit is connected to the first-end ranging feeder terminal via a coaxial cable; the through-core sensor in the last-end coupling capacitor circuit is connected to the last-end ranging feeder terminal via a coaxial cable.

[0013] When measuring line parameters, all three-phase switches in the first-end coupling capacitor circuit and the last-end coupling capacitor circuit are open, and a high-frequency pulse signal is injected into one end of any two phase switches in the first-end coupling capacitor circuit. The sensor in the first-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the first-end ranging feeder terminal, and the sensor in the last-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the last-end ranging feeder terminal.

[0014] Both the first-end ranging feeder terminal and the last-end ranging feeder terminal include: a time synchronization module and a wireless communication module, which are used to achieve clock synchronization according to the time synchronization module, and to send the detected high-frequency pulse signal to the ranging master station through the wireless communication module after marking it with a time stamp;

[0015] The times when the high-frequency pulse signal arrives at the first-end ranging feeder terminal and the last-end ranging feeder terminal are used as the corresponding time stamps.

[0016] When wave velocity measurement is not required, the three-phase switches of the head-end coupling capacitor circuit and the tail-end coupling capacitor circuit are closed. In the event of a fault, the sensor in the head-end coupling capacitor circuit will transmit the detected fault traveling wave signal to the head-end ranging feeder terminal, and the sensor in the tail-end coupling capacitor circuit will transmit the detected fault traveling wave signal to the tail-end ranging feeder terminal.

[0017] Both the first-end ranging feeder terminal and the last-end ranging feeder terminal include: a time synchronization module and a wireless communication module, which are used to achieve clock synchronization according to the time synchronization module, and to send the detected fault traveling wave signal to the ranging master station through the wireless communication module after marking it with a time stamp;

[0018] The times when the fault traveling wave signal arrives at the first-end ranging feeder terminal and the last-end ranging feeder terminal are respectively used as the corresponding time stamps.

[0019] The distribution network line is equipped with a primary and secondary integrated switchgear at both the beginning and end. The primary and secondary integrated switchgear installed at the beginning of the distribution network line includes a pole-mounted switch and a coupling capacitor circuit connected in parallel at the beginning. The primary and secondary integrated switchgear installed at the end of the distribution network line includes a pole-mounted switch and a coupling capacitor circuit connected in parallel at the end.

[0020] This invention also proposes a method for measuring distribution network line parameters and locating faults based on signal injection, comprising:

[0021] After the high-frequency pulse signal is injected into the first-end coupling capacitor circuit, it flows through the power distribution line and the last-end coupling capacitor circuit in sequence; the first-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the first-end ranging feeder terminal, and the last-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the last-end ranging feeder terminal.

[0022] The first-end ranging feeder terminal adds a first time stamp to the arriving high-frequency pulse signal and sends it to the ranging master station; the last-end ranging feeder terminal adds a second time stamp to the arriving high-frequency pulse signal and sends it to the ranging master station; the ranging master station calculates the actual wave velocity of the line based on the line length, the first time stamp, and the second time stamp;

[0023] The first-end coupling capacitor circuit transmits the detected fault traveling wave signal to the first-end ranging feeder terminal, and the last-end coupling capacitor circuit transmits the detected fault traveling wave signal to the last-end ranging feeder terminal. The first-end ranging feeder terminal adds a third time stamp to the arriving fault traveling wave signal and sends it to the ranging master station. The last-end ranging feeder terminal adds a fourth time stamp to the arriving fault traveling wave signal and sends it to the ranging master station. The ranging master station calculates the fault distance based on the line length, the actual line wave velocity, the third time stamp, and the fourth time stamp.

[0024] The actual wave velocity v of the line satisfies the following relationship:

[0025]

[0026] In the formula, L is the line length, t1 is the first time scale, and t2 is the second time scale.

[0027] Fault distance L f The following relationship must be satisfied:

[0028]

[0029] In the formula, t3 is the third time scale, t4 is the fourth time scale, and v is the actual wave velocity of the line.

[0030] The beneficial effects of this invention are that, compared with the prior art, it at least includes:

[0031] (1) The capacitor coupling circuit proposed in this invention is arranged in the primary and secondary integrated switch, realizing the integration of equipment. The equipment can be installed as a set, which effectively improves the integrity of the equipment and reduces manufacturing costs. At the same time, the installation and maintenance are more convenient and suitable for practical engineering applications.

[0032] (2) Compared with the currently widely used offline injection scheme, the wave velocity measurement scheme proposed in this invention allows for the human to autonomously select the signal injection time without power interruption, and to measure and calibrate the line parameters online at any time and quickly without changing the line structure and operation mode, thus having strong applicability.

[0033] (3) By switching the state of the components in the capacitive coupling circuit proposed in this invention, the fault traveling wave and the injected pulse signal during line parameter measurement can be detected respectively during system operation. That is, the same set of equipment can realize both traveling wave fault location and line wave velocity measurement and calibration. Moreover, the measurement of line wave velocity is beneficial to improving the accuracy and reliability of traveling wave fault location in distribution network lines. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of a system for measuring distribution network line parameters and locating faults, provided in an embodiment of the present invention.

[0035] Figure 2 This is a schematic diagram of the coupling capacitor circuit provided in an embodiment of the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of this invention. The embodiments described in this application are merely some embodiments of this invention, and not all embodiments. Based on the spirit of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this invention.

[0037] This invention proposes a distribution network line parameter measurement and fault location system based on signal injection, comprising: a head-end coupling capacitor circuit installed at the head end of the distribution network line, an end-end coupling capacitor circuit installed at the end of the distribution network line, a head-end ranging feeder terminal, an end-end ranging feeder terminal, and a ranging master station;

[0038] Furthermore, the first-end coupling capacitor circuit is installed in the primary and secondary integrated switchgear at the first end of the distribution network line, and the last-end coupling capacitor circuit is installed in the primary and secondary integrated switchgear at the last end of the distribution network line.

[0039] like Figure 1 As shown, the signal injection device includes a pulse signal generator 11. In this embodiment, a handheld pulse signal injection device is used to output a high-frequency voltage pulse signal with a specific frequency and amplitude. The primary and secondary integrated switchgear installed at the beginning of the distribution network line includes a pole-mounted switch 21 and a coupling capacitor circuit 23 connected in parallel. The primary and secondary integrated switchgear installed at the end of the distribution network line includes a pole-mounted switch 22 and a coupling capacitor circuit 24 connected in parallel. The coupling capacitor circuit proposed in this invention is arranged within the primary and secondary integrated switchgear, realizing equipment integration. The equipment can be installed as a set, effectively improving the integrity of the equipment and reducing manufacturing costs. At the same time, installation and maintenance are more convenient, making it suitable for practical engineering applications. The starting-end ranging feeder terminal 25 is installed at the beginning of the line, and the ending-end ranging feeder terminal 26 is installed at the end of the line. The starting-end coupling capacitor circuit is connected in parallel with the starting-end pole-mounted switch for injecting pulse signals, and the ending-end coupling capacitor circuit is connected in parallel with the ending-end pole-mounted switch for detecting pulse signals. The system master station includes a ranging master station 30, which interacts with the first-end ranging feeder terminal 25 and the last-end ranging feeder terminal 26 via a data network 40.

[0040] When measuring line parameters, a high-frequency pulse signal is injected into the first-end coupling capacitor circuit and then flows sequentially through the distribution line and the last-end coupling capacitor circuit. The first-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the first-end ranging feeder terminal, and the last-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the last-end ranging feeder terminal. The first-end and last-end ranging feeder terminals respectively send the time-stamped high-frequency pulse signal to the ranging master station. The ranging master station, based on dual-end ranging technology, calculates the actual wave velocity of the line according to the line length.

[0041] Compared with the currently widely used offline injection scheme, the wave velocity measurement scheme proposed in this invention allows for the human to independently select the signal injection time without power interruption, enabling online measurement and calibration of line parameters at any time and quickly, without changing the line structure and operating mode, thus having strong applicability.

[0042] Preferably, both the first-end ranging feeder terminal and the last-end ranging feeder terminal include: a time synchronization module and a wireless communication module, used to achieve clock synchronization according to the time synchronization module, and to send the detected high-frequency pulse signal to the ranging master station through the wireless communication module after marking it with a time stamp;

[0043] The times when the high-frequency pulse signal arrives at the first-end ranging feeder terminal and the last-end ranging feeder terminal are used as the corresponding time stamps.

[0044] like Figure 2 As shown, both the first-end coupling capacitor circuit and the last-end coupling capacitor circuit include: capacitors C1, C2, and C3 installed on the three phases of the line; through-hole sensors R1, R2, and R3; inductors L1, L2, and L3; and switches K1, K2, and K3. One end of the capacitor is connected to the distribution network line, and the other end of the capacitor is connected to one end of the inductor and one end of the switch. The other end of the inductor is grounded, and the other end of the switch is grounded. The through-hole sensors are connected in series on the connection line between the capacitor and the inductor.

[0045] In this circuit, one end of any two phase switches in the first-end coupling capacitor circuit is connected to a pulse signal generator, which is used to output a high-frequency pulse signal with a set frequency and amplitude.

[0046] Furthermore, the through-core sensor in the first-end coupling capacitor circuit is connected to the first-end ranging feeder terminal via a coaxial cable; the through-core sensor in the last-end coupling capacitor circuit is connected to the last-end ranging feeder terminal via a coaxial cable.

[0047] Specifically, when measuring line parameters, switches K1, K2, and K3 of the beginning and end coupling capacitor circuits are disconnected. At this time, capacitors C1, C2, and C3 in the beginning and end coupling capacitor circuits are connected in series with inductors L1, L2, and L3 and grounded. The output terminal of the pulse signal generator is connected to one end of any two switches in the beginning coupling capacitor circuit. Figure 2Any two of a, b, and c inject high-frequency pulse signals into the phase-to-phase line. Under the blocking effect of the inductor on the high-frequency signal, the high-frequency pulse signal flows sequentially through the through-hole sensor R1 of the first-end coupling capacitor circuit, the capacitor C1 of the first-end coupling capacitor circuit, the distribution network line, the capacitor C1 of the last-end coupling capacitor circuit, and the through-hole sensor R1 of the last-end coupling capacitor circuit. The sensor of the first-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the first-end ranging feeder terminal using a coaxial cable 50, and the sensor of the last-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the last-end ranging feeder terminal using a coaxial cable 50.

[0048] When a line fault occurs and the fault distance needs to be measured, the first-end coupling capacitor circuit transmits the detected fault traveling wave signal to the first-end ranging feeder terminal, and the last-end coupling capacitor circuit transmits the detected fault traveling wave signal to the last-end ranging feeder terminal. The first-end and last-end ranging feeder terminals respectively send the time-stamped fault traveling wave signal to the ranging master station. The ranging master station, based on dual-end ranging technology, calculates the fault distance according to the actual wave velocity of the line.

[0049] Specifically, when wave velocity measurement is not required, switches K1, K2, and K3 of the head-end coupling capacitor circuit and the tail-end coupling capacitor circuit are closed, and capacitors C1, C2, and C3 are grounded through switches K1, K2, and K3 respectively. When a line fault occurs, the sensor in the head-end coupling capacitor circuit transmits the fault traveling wave signal detected in real time to the head-end ranging feeder terminal via a coaxial cable, and the sensor in the tail-end coupling capacitor circuit transmits the fault traveling wave signal detected in real time to the tail-end ranging feeder terminal via a coaxial cable.

[0050] Preferably, the first-end ranging feeder terminal and the last-end ranging feeder terminal are also used to achieve clock synchronization according to the time synchronization module, and to send the detected fault traveling wave signal to the ranging master station through the wireless communication module after marking it with a time stamp;

[0051] The times when the fault traveling wave signal arrives at the first-end ranging feeder terminal and the last-end ranging feeder terminal are respectively used as the corresponding time stamps.

[0052] This invention changes the electrical connection relationship of components in the first-end coupling capacitor circuit and the last-end coupling capacitor circuit by switching the conduction and closing operations of the switch, thereby realizing the measurement of the actual wave velocity and fault distance of the distribution network line under normal operation without power interruption. The actual wave velocity and fault distance are used as the output results of the distribution network line parameter measurement and fault location system.

[0053] Using the same set of equipment can provide corresponding parameters for fault traveling wave location, as well as for line wave velocity measurement and calibration. Moreover, the actual line wave velocity calculated by the ranging master station corresponds to a time-stamped high-frequency pulse signal, and the fault traveling wave velocity corresponds to a time-stamped fault traveling wave signal. The closest actual line wave velocity can characterize the time of fault occurrence. Due to the influence of factors such as frequency changes and climate change on the actual wave velocity of distribution network lines, the closest actual line wave velocity is selected based on the time stamp to correct the fault traveling wave velocity, thereby correcting the fault location and improving the accuracy and reliability of traveling wave fault location in distribution network lines.

[0054] In this embodiment, the ranging master station pre-stores the length of the distribution network line, calculates the actual wave velocity or fault distance of the line based on the dual-end ranging technology, and stores the calculated actual wave velocity of the line together with the time stamp of the corresponding high-frequency pulse signal.

[0055] This invention also proposes a method for measuring distribution network line parameters and locating faults based on signal injection, comprising the following steps:

[0056] Step 1: After the high-frequency pulse signal is injected into the first-end coupling capacitor circuit, it flows through the power distribution line and the last-end coupling capacitor circuit in sequence; the first-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the first-end ranging feeder terminal, and the last-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the last-end ranging feeder terminal.

[0057] Specifically, when measuring line parameters, the three-phase switches of the first-end coupling capacitor circuit and the last-end coupling capacitor circuit are simultaneously disconnected, and a high-frequency pulse signal is injected into the first-end coupling capacitor circuit using a pulse signal generator.

[0058] Step 2: The first-end ranging feeder terminal adds a first time stamp to the arriving high-frequency pulse signal and sends it to the ranging master station; the last-end ranging feeder terminal adds a second time stamp to the arriving high-frequency pulse signal and sends it to the ranging master station; the ranging master station calculates the actual wave velocity of the line based on the line length, the first time stamp, and the second time stamp.

[0059] Specifically, the actual wave velocity v of the line satisfies the following relationship:

[0060]

[0061] In the formula, L is the line length, t1 is the first time scale, and t2 is the second time scale.

[0062] Step 3: The first-end coupling capacitor circuit transmits the detected fault traveling wave signal to the first-end ranging feeder terminal, and the last-end coupling capacitor circuit transmits the detected fault traveling wave signal to the last-end ranging feeder terminal; the first-end ranging feeder terminal adds a third time stamp to the arriving fault traveling wave signal and sends it to the ranging master station; the last-end ranging feeder terminal adds a fourth time stamp to the arriving fault traveling wave signal and sends it to the ranging master station; the ranging master station calculates the fault distance based on the line length, the actual wave velocity of the line, the third time stamp, and the fourth time stamp.

[0063] Specifically, the fault distance L f The following relationship must be satisfied:

[0064]

[0065] In the formula, t3 is the third time scale, t4 is the fourth time scale, and v is the actual wave velocity of the line.

[0066] This disclosure can be a system, method, and / or computer program product. A computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for causing a processor to implement various aspects of this disclosure.

[0067] Computer-readable storage media can be tangible devices capable of holding and storing instructions for use by an instruction execution device. Computer-readable storage media can be, for example—but not limited to—electrical storage devices, magnetic storage devices, optical storage devices, electromagnetic storage devices, semiconductor storage devices, or any suitable combination of the foregoing. More specific examples (a non-exhaustive list) of computer-readable storage media include: portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), static random access memory (SRAM), portable compact disc read-only memory (CD-ROM), digital multifunction disc (DVD), memory sticks, floppy disks, mechanical encoding devices, such as punch cards or recessed protrusions storing instructions thereon, and any suitable combination of the foregoing. The computer-readable storage media used herein are not to be construed as transient signals themselves, such as radio waves or other freely propagating electromagnetic waves, electromagnetic waves propagating through waveguides or other transmission media (e.g., light pulses through fiber optic cables), or electrical signals transmitted through wires.

[0068] The computer-readable program instructions described herein can be downloaded from computer-readable storage media to various computing / processing devices, or downloaded via a network, such as the Internet, local area network, wide area network, and / or wireless network, to an external computer or external storage device. The network may include copper transmission cables, fiber optic transmission, wireless transmission, routers, firewalls, switches, gateway computers, and / or edge servers. A network adapter card or network interface in each computing / processing device receives the computer-readable program instructions from the network and forwards them to the computer-readable storage media in the respective computing / processing device.

[0069] Computer program instructions used to perform the operations of this disclosure may be assembly instructions, instruction set architecture (ISA) instructions, machine instructions, machine-dependent instructions, microcode, firmware instructions, status setting data, or source code or object code written in any combination of one or more programming languages, including object-oriented programming languages ​​such as Smalltalk, C++, etc., and conventional procedural programming languages ​​such as the "C" language or similar programming languages. The computer-readable program instructions may execute entirely on the user's computer, partially on the user's computer, as a standalone software package, partially on the user's computer and partially on a remote computer, or entirely on a remote computer or server. In cases involving a remote computer, the remote computer may be connected to the user's computer via any type of network—including a local area network (LAN) or a wide area network (WAN)—or may be connected to an external computer (e.g., via the Internet using an Internet service provider). In some embodiments, electronic circuitry, such as programmable logic circuitry, field-programmable gate arrays (FPGAs), or programmable logic arrays (PLAs), is personalized by utilizing the status information of the computer-readable program instructions to implement various aspects of this disclosure.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the protection scope of the claims of the present invention.

Claims

1. A distribution network line parameter measurement and fault location system based on signal injection, characterized in that, The system includes: a head-end coupling capacitor circuit installed at the head end of the distribution network line, an end-end coupling capacitor circuit installed at the end of the distribution network line, a head-end ranging feeder terminal, an end-end ranging feeder terminal, and a ranging master station; Both the first-end coupling capacitor circuit and the last-end coupling capacitor circuit include: a three-phase capacitor, a three-phase through-hole sensor, a three-phase inductor, and a three-phase switch; in each phase, one end of the capacitor is connected to the distribution network line, and the other end of the capacitor is connected to one end of the inductor and one end of the switch. The other end of the inductor is grounded, and the other end of the switch is grounded. The through-hole sensor is connected in series on the connection line between the capacitor and the inductor; the through-hole sensor in the first-end coupling capacitor circuit is connected to the first-end ranging feeder terminal via a coaxial cable; the through-hole sensor in the last-end coupling capacitor circuit is connected to the last-end ranging feeder terminal via a coaxial cable. When measuring line parameters, all three-phase switches in both the head-end and tail-end coupling capacitor circuits are open. A high-frequency pulse signal is injected into one end of any two phase switches in the head-end coupling capacitor circuit. This high-frequency pulse signal flows sequentially through the distribution line and the tail-end coupling capacitor circuit. The head-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the head-end ranging feeder terminal, and the tail-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the tail-end ranging feeder terminal. Both the head-end and tail-end ranging feeder terminals send time-stamped high-frequency pulse signals to the ranging master station. The ranging master station calculates the actual wave velocity of the line. When a line fault occurs, the three-phase switches of both the head-end coupling capacitor circuit and the tail-end coupling capacitor circuit close. The head-end coupling capacitor circuit transmits the detected fault traveling wave signal to the head-end ranging feeder terminal, and the tail-end coupling capacitor circuit transmits the detected fault traveling wave signal to the tail-end ranging feeder terminal. The head-end and tail-end ranging feeder terminals respectively send the time-stamped fault traveling wave signal to the ranging master station. The ranging master station calculates the fault distance based on the line length, the actual line wave velocity, and the time stamp of the fault traveling wave signal. The actual wave velocity and fault distance of the line are used as the output results of the distribution network line parameter measurement and fault location system.

2. The distribution network line parameter measurement and fault location system based on signal injection according to claim 1, characterized in that, One end of any two phase switches in the first-end coupling capacitor circuit is connected to a pulse signal generator, which is used to output a high-frequency pulse signal with a set frequency and amplitude.

3. The distribution network line parameter measurement and fault location system based on signal injection according to claim 1, characterized in that, When measuring line parameters, the sensor in the first-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the first-end ranging feeder terminal, and the sensor in the last-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the last-end ranging feeder terminal.

4. The distribution network line parameter measurement and fault location system based on signal injection according to claim 3, characterized in that, Both the first-end ranging feeder terminal and the last-end ranging feeder terminal include: a time synchronization module and a wireless communication module, which are used to achieve clock synchronization according to the time synchronization module, and to send the detected high-frequency pulse signal to the ranging master station through the wireless communication module after marking it with a time stamp; The times when the high-frequency pulse signal arrives at the first-end ranging feeder terminal and the last-end ranging feeder terminal are used as the corresponding time stamps.

5. The distribution network line parameter measurement and fault location system based on signal injection according to claim 1, characterized in that, When wave velocity measurement is not required, in the event of a fault, the sensor in the first-end coupling capacitor circuit will transmit the detected fault traveling wave signal to the first-end ranging feeder terminal, and the sensor in the last-end coupling capacitor circuit will transmit the detected fault traveling wave signal to the last-end ranging feeder terminal.

6. The distribution network line parameter measurement and fault location system based on signal injection according to claim 5, characterized in that, Both the first-end ranging feeder terminal and the last-end ranging feeder terminal include: a time synchronization module and a wireless communication module, which are used to achieve clock synchronization according to the time synchronization module, and to send the detected fault traveling wave signal to the ranging master station through the wireless communication module after marking it with a time stamp; The times when the fault traveling wave signal arrives at the first-end ranging feeder terminal and the last-end ranging feeder terminal are respectively used as the corresponding time stamps.

7. The distribution network line parameter measurement and fault location system based on signal injection according to claim 1, characterized in that, The distribution network line is equipped with a primary and secondary integrated switchgear at both the beginning and end. The primary and secondary integrated switchgear installed at the beginning of the distribution network line includes a pole-mounted switch and a coupling capacitor circuit connected in parallel at the beginning. The primary and secondary integrated switchgear installed at the end of the distribution network line includes a pole-mounted switch and a coupling capacitor circuit connected in parallel at the end.

8. A method for measuring distribution network line parameters and locating faults based on signal injection, implemented using the distribution network line parameter measurement and fault location system based on signal injection as described in any one of claims 1 to 7, characterized in that, include: After the high-frequency pulse signal is injected into the first-end coupling capacitor circuit, it flows through the power distribution line and the last-end coupling capacitor circuit in sequence; the first-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the first-end ranging feeder terminal, and the last-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the last-end ranging feeder terminal. The first-end ranging feeder terminal adds the first time stamp to the arriving high-frequency pulse signal and sends it to the ranging master station; The end-of-line ranging feeder terminal sends the arriving high-frequency pulse signal with a second time stamp to the ranging master station; the ranging master station calculates the actual wave velocity of the line based on the line length, the first time stamp, and the second time stamp. The first-end coupling capacitor circuit transmits the detected fault traveling wave signal to the first-end ranging feeder terminal, and the last-end coupling capacitor circuit transmits the detected fault traveling wave signal to the last-end ranging feeder terminal. The first-end ranging feeder terminal sends the arriving fault traveling wave signal with a third time stamp to the ranging master station; The end-of-line ranging feeder terminal sends the arriving fault traveling wave signal with a fourth time stamp to the ranging master station; The distance measuring master station calculates the fault distance based on the line length, the actual wave velocity of the line, and the third and fourth time scales.

9. The method for measuring distribution network line parameters and locating faults based on signal injection according to claim 8, characterized in that, Actual wave speed of the line The following relationship must be satisfied: In the formula, L is the line length. As the first time scale, This is the second time scale.

10. The method for measuring distribution network line parameters and locating faults based on signal injection according to claim 8, characterized in that, The fault distance Lf satisfies the following relationship: In the formula, It is the third time scale. The fourth timescale is denoted by v, which represents the actual wave velocity of the line.

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