Distribution network line parameter measurement and fault location system and method based on signal injection

Abstract

A distribution network line parameter measurement and fault location system and method based on signal injection. A high-frequency pulse signal is injected into a head-end coupling capacitor circuit (23) and then sequentially flows through a distribution line and a tail-end coupling capacitor circuit (24); the head-end and tail-end coupling capacitor circuits (23, 24) transmit the detected high-frequency pulse signal to head-end and tail-end distance measurement feeder terminals (25, 26), and the head-end and tail-end distance measurement feeder terminals (25, 26) respectively send a time-stamped high-frequency pulse signal to the distance measurement master station (30); the distance measurement master station (30) calculates the actual wave velocity of the line; the head-end and tail-end coupling capacitor circuits (23, 24) transmit a detected fault traveling wave signal to the head-end and tail-end distance measurement feeder terminals (25, 26), and the head-end and tail-end distance measurement feeder terminals (25, 26) respectively send a time-stamped fault traveling wave signal to the distance measurement master station (30); and the distance measurement master station (30) calculates a fault distance. The actual wave velocity and the fault distance of the line are used as output results of the distribution network line parameter measurement and fault location system. The wave velocity of the line is accurately measured, thereby solving the problem of distance measurement errors caused by inaccurate wave velocity.

Description

A System and Method for Distribution Network Line Parameter Measurement and Fault Location Based on Signal Injection

[0001] Related applications

[0002] This application claims priority to Chinese Patent Application No. 202410689770.5, filed on May 30, 2024, entitled "System and Method for Measurement and Fault Location of Distribution Network Line Parameters Based on Signal Injection", the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application 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

[0004] 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.

[0005] 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

[0006] To address the shortcomings of existing technologies, this application 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.

[0007] The technical solution adopted in this application is as follows.

[0008] This application 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.

[0009] When measuring line parameters, a high-frequency pulse signal is injected into the first-end coupling capacitor circuit and 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 time-stamped high-frequency pulse signals to the ranging master station. The ranging master station calculates the actual wave velocity of the line.

[0010] 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;

[0011] The actual wave velocity of the line and the fault distance are used as the output results of the distribution network line parameter measurement and the fault location system.

[0012] 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, 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, the other end of the switch is grounded, and the through-hole sensor is connected in series on the connection line between the capacitor and the inductor.

[0013] One end of any two phase switches in the three-phase switch 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.

[0014] 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.

[0015] When measuring line parameters, the three-phase switches of the first-end coupling capacitor circuit and the last-end coupling capacitor circuit are both disconnected, and the high-frequency pulse signal is injected into one end of any two phase switches in the first-end coupling capacitor circuit. The through-core sensor of the first-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the first-end ranging feeder terminal, and the through-core sensor of the last-end coupling capacitor circuit transmits the detected high-frequency pulse signal to the last-end ranging feeder terminal.

[0016] 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;

[0017] The times when the high-frequency pulse signal arrives at the first-end ranging feeder terminal and the last-end ranging feeder terminal are respectively used as corresponding time stamps.

[0018] When wave velocity measurement is not required, the three-phase switches of the first-end coupling capacitor circuit and the last-end coupling capacitor circuit are both closed. In the event of a fault, the through-core sensor of the first-end coupling capacitor circuit transmits the detected fault traveling wave signal to the first-end ranging feeder terminal, and the through-core sensor of the last-end coupling capacitor circuit transmits the detected fault traveling wave signal to the last-end ranging feeder terminal.

[0019] 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 fault traveling wave signal to the ranging master station through the wireless communication module after adding a time stamp;

[0020] 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 corresponding time stamps.

[0021] 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 at the beginning and a coupling capacitor circuit at the beginning, which are connected in parallel. The primary and secondary integrated switchgear installed at the end of the distribution network line includes a pole-mounted switch at the end and a coupling capacitor circuit at the end, which are connected in parallel.

[0022] This application also proposes a method for measuring distribution network line parameters and locating faults based on signal injection, including:

[0023] After the high-frequency pulse signal is injected into the first-end coupling capacitor circuit, it flows sequentially through the power 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.

[0024] 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;

[0025] 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;

[0026] The actual wave velocity v of the line satisfies the following relationship:

[0027] In the formula, L is the line length, t1 is the first time scale, and t2 is the second time scale.

[0028] Fault distance L f The following relationship must be satisfied:

[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 application are that, compared with the prior art, it includes at least the following:

[0031] (1) The capacitor coupling circuit proposed in this application 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 the manufacturing cost. 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 application allows for the human to independently 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 application, 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 is a schematic diagram of a system for measuring and locating faults in a distribution network line according to an embodiment of this application;

[0035] Figure 2 is a schematic diagram of a coupling capacitor circuit provided in an embodiment of this application. Detailed Implementation

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

[0037] This application proposes a distribution network line parameter measurement and fault location system based on signal injection, including: a head-end coupling capacitor circuit installed at the head end of the distribution network line, an end coupling capacitor circuit installed at the end of the distribution network line, a head-end ranging feeder terminal, an 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] As shown in Figure 1, the signal injection device includes a pulse signal generator 11. In one 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 application 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 widely used offline injection scheme, the wave velocity measurement scheme proposed in this application 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 operation mode, thus having strong applicability.

[0042] In one embodiment, 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] As shown in Figure 2, 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 first-end coupling capacitor circuit and the last-end coupling capacitor circuit are disconnected. At this time, capacitors C1, C2, and C3 in the first-end coupling capacitor circuit and the last-end coupling capacitor circuit 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 first-end coupling capacitor circuit, i.e., any two of a, b, and c in Figure 2, injecting high-frequency pulse signals into the phases of the line. Under the blocking effect of the inductor on the high-frequency signal, the high-frequency pulse signal flows sequentially through the through-core sensor R1 of the first-end coupling capacitor circuit, capacitor C1 of the first-end coupling capacitor circuit, the distribution network line, capacitor C1 of the last-end coupling capacitor circuit, and through-core sensor R1 of the last-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 using a coaxial cable 50, and the sensor in 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] In one embodiment, the first-end ranging feeder terminal and the last-end ranging feeder terminal are also used to synchronize the clock 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 application 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, so as to realize the measurement of the actual wave velocity and the fault distance of the distribution network line under the condition of 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 application also proposes a method for measuring distribution network line parameters and locating faults based on signal injection, including 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] In the formula, L is the line length, t1 is the first time scale, and t2 is the second time scale.

[0061] 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.

[0062] Specifically, the fault distance L f The following relationship must be satisfied:

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and not to limit them. Although this application 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 this application. Any modifications or equivalent substitutions that do not depart from the spirit and scope of this application should be covered within the protection scope of the claims of this application.

Claims

1. A signal injection based network commissioning line parameter measurement and fault location system, wherein, The system comprises a head-end coupling capacitor loop installed at the head end of the distribution network line, a tail-end coupling capacitor loop installed at the tail end of the distribution network line, a head-end ranging feeder terminal, a tail-end ranging feeder terminal and a ranging master station; When measuring the line parameters, the high-frequency pulse signal injected into the head-end coupling capacitor loop flows through the distribution network line and the tail-end coupling capacitor loop in turn; the head-end coupling capacitor loop transmits the detected high-frequency pulse signal to the head-end ranging feeder terminal, and the tail-end coupling capacitor loop transmits the detected high-frequency pulse signal to the tail-end ranging feeder terminal; the head-end ranging feeder terminal and the tail-end ranging feeder terminal respectively send the high-frequency pulse signal marked with a time stamp to the ranging master station; the ranging master station calculates the actual wave speed of the line; When a fault occurs in the line, the head-end coupling capacitor loop transmits the detected fault traveling wave signal to the head-end ranging feeder terminal, and the tail-end coupling capacitor loop transmits the detected fault traveling wave signal to the tail-end ranging feeder terminal; the head-end ranging feeder terminal and the tail-end ranging feeder terminal respectively send the fault traveling wave signal marked with a time stamp to the ranging master station; the ranging master station calculates the fault distance according to the actual wave speed of the line; The actual wave speed of the line and the fault distance are output results of the distribution network line parameter measurement and fault location system.

2. The signal injection-based distribution network line parameter measurement and fault location system according to claim 1, wherein The head-end coupling capacitor loop and the tail-end coupling capacitor loop each comprise a three-phase capacitor, a three-phase core-penetrating 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, 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, the other end of the switch is grounded, and the core-penetrating sensor is connected in series to the connection line between the capacitor and the inductor.

3. The signal injection-based distribution network line parameter measurement and fault location system according to claim 2, wherein One end of any two-phase switch in the three-phase switch in the head-end coupling capacitor loop is connected to a pulse signal generating device, and the pulse signal generating device is used to output a high-frequency pulse signal with a set frequency and amplitude.

4. The signal injection-based distribution network line parameter measurement and fault location system according to claim 3, wherein The core-penetrating sensor in the head-end coupling capacitor loop is connected to the head-end ranging feeder terminal through a coaxial cable; and the core-penetrating sensor in the tail-end coupling capacitor loop is connected to the tail-end ranging feeder terminal through a coaxial cable.

5. The signal injection-based distribution network line parameter measurement and fault location system according to claim 4, wherein When measuring line parameters, the three-phase switches of the head-end coupling capacitor loop and the tail-end coupling capacitor loop are both open, and one end of any two of the three-phase switches in the head-end coupling capacitor loop injects the high-frequency pulse signal, the head-end core-penetrating sensor of the head-end coupling capacitor loop transmits the detected high-frequency pulse signal to the head-end ranging feeder terminal, and the tail-end core-penetrating sensor of the tail-end coupling capacitor loop transmits the detected high-frequency pulse signal to the tail-end ranging feeder terminal.

6. The signal injection-based distribution network line parameter measurement and fault location system according to claim 5, wherein, The head-end ranging feeder terminal and the tail-end ranging feeder terminal both comprise a time synchronization module and a wireless communication module, which are used to realize clock synchronization according to the time synchronization module, and send the detected high-frequency pulse signal to the ranging master station through the wireless communication module after marking the high-frequency pulse signal with a time tag; wherein the time when the high-frequency pulse signal reaches the head-end ranging feeder terminal and the tail-end ranging feeder terminal respectively serves as the corresponding time tag.

7. The signal injection-based distribution network line parameter measurement and fault location system according to claim 4, wherein, When the wave speed is not required to be measured, the three-phase switches of the head-end coupling capacitor loop and the tail-end coupling capacitor loop are both closed, and when a fault occurs, the core-penetrating sensor of the head-end coupling capacitor loop transmits the detected fault traveling wave signal to the head-end ranging feeder terminal, and the core-penetrating sensor of the tail-end coupling capacitor loop transmits the detected fault traveling wave signal to the tail-end ranging feeder terminal.

8. The signal injection-based distribution network line parameter measurement and fault location system according to claim 7, wherein, The head-end ranging feeder terminal and the tail-end ranging feeder terminal both comprise a time synchronization module and a wireless communication module, which are used to realize clock synchronization according to the time synchronization module, and send the detected fault traveling wave signal to the ranging master station through the wireless communication module after marking the fault traveling wave signal with a time tag; wherein the time when the fault traveling wave signal reaches the head-end ranging feeder terminal and the tail-end ranging feeder terminal respectively serves as the corresponding time tag.

9. The signal injection-based distribution network line parameter measurement and fault location system according to claim 1, wherein, The head end and the tail end of the distribution network line are respectively configured with a secondary fusion switch complete set of equipment, the secondary fusion switch complete set of equipment installed at the head end of the distribution network line comprises a head-end pole switch and the head-end coupling capacitor loop connected in parallel, and the secondary fusion switch complete set of equipment installed at the tail end of the distribution network line comprises a tail-end pole switch and the tail-end coupling capacitor loop connected in parallel.

10. A method for signal injection based network commissioning line parameter measurement and fault location, wherein, comprises: The high-frequency pulse signal injected into the head-end coupling capacitor loop flows through the distribution network line and the tail-end coupling capacitor loop in turn; the head-end coupling capacitor loop transmits the detected high-frequency pulse signal to the head-end ranging feeder terminal, and the tail-end coupling capacitor loop transmits the detected high-frequency pulse signal to the tail-end ranging feeder terminal; The first time mark is stamped on the high-frequency pulse signal arriving at the first end ranging feeder terminal and sent to the ranging master station; the second time mark is stamped on the high-frequency pulse signal arriving at the last end ranging feeder terminal and sent to the ranging master station; the ranging master station calculates the actual wave speed of the line according to the line length, the first time mark and the second time mark; The first end coupling capacitor loop transmits the detected fault traveling wave signal to the first end ranging feeder terminal, and the last end coupling capacitor loop transmits the detected fault traveling wave signal to the last end ranging feeder terminal; the third time mark is stamped on the fault traveling wave signal arriving at the first end ranging feeder terminal and sent to the ranging master station; the fourth time mark is stamped on the fault traveling wave signal arriving at the last end ranging feeder terminal and sent to the ranging master station; the ranging master station calculates the fault distance according to the line length, the actual wave speed of the line, the third time mark and the fourth time mark; 11. The signal injection-based distribution network line parameter measurement and fault location method according to claim 10, wherein, The actual wave speed v of the line satisfies the following relationship: In the formula, L is the line length, t1 is the first time mark, and t2 is the second time mark.

12. The signal injection-based distribution network line parameter measurement and fault location method according to claim 10, wherein, Fault distance L f satisfies the following relationship: In the formula, t3 is the third time mark, t4 is the fourth time mark, and v is the actual wave speed of the line.

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