High-precision power transmission line distributed fault positioning method, device and system

Abstract

The invention discloses a high-precision power transmission line distributed fault positioning method, device and system wherein the high-precision power transmission line distributed fault positioning device is deployed on each node of a power transmission line and comprises an MCU main control unit and a time-to-digital converter electrically connected with the MCU main control unit; the time-to-digital converter is used for capturing a traveling wave signal, a 1PPS signal of a Beidou satellite and a local OCXO clock signal of a current high-precision power transmission line distributed fault positioning device. According to the technical scheme, the error of obtaining the time reference is smaller than 10 ns, the fault rate of data transmission is also greatly reduced, and under the condition that the Beidou time service chip signal is abnormal and time service cannot be carried out, the technical scheme has OCXO dynamic taming punctuality so as to ensure stable operation of equipment, and not only is the high-precision requirement met, but also the fine operation and maintenance requirement can be met.

Description

Technical Field

[0001] The present invention relates to the technical field of transmission line fault location, and in particular to a high-precision transmission line distributed fault location method, device and system. Background Art

[0002] Transmission lines are a core component of the power system, and their safe and stable operation is directly related to grid reliability. When a line fault such as a short circuit or grounding occurs, quickly and accurately locating the fault point is a key technical challenge to shorten repair time and minimize economic losses.

[0003] The current mainstream fault location methods mainly include impedance location method and traveling wave location method, each of which has its own shortcomings:

[0004] 1) Impedance location. This method estimates distance based on the post-fault voltage and current phase relationship. While it does not require high-precision time synchronization, it is susceptible to interference from factors such as line parameter asymmetry, transition resistance, and system oscillation. Positioning errors can often reach 2% to 5% of the total line length, making it difficult to meet high-precision requirements.

[0005] 2) Traveling wave positioning. This method uses the time difference between the arrival of high-frequency transient traveling wave signals generated by the fault at different monitoring points to calculate the fault location. This method offers high positioning accuracy (theoretical error <500 meters), but places extremely stringent requirements on time synchronization accuracy (needing to reach the nanosecond level). Existing systems primarily rely on GPS or Beidou timing modules for time synchronization, but this method is susceptible to limitations imposed by the closed-loop technology of the original manufacturer. This prevents developers from directly obtaining absolute time and only allows them to utilize the 1PPS signal, forcing secondary processing through MCU interrupts. This limits traveling wave positioning accuracy to the 100-meter level, still failing to meet high-precision requirements.

[0006] Furthermore, the distributed fault diagnosis systems that have emerged in recent years deploy monitoring terminals (such as intelligent fault indicators) at multiple nodes along the transmission line, leveraging the differences in timestamps when fault signals arrive at each node to achieve location. However, the positioning accuracy of existing terminals is limited to the "segment level," meaning a range greater than 1 kilometer. Furthermore, the accuracy of distributed positioning fundamentally depends on the resolution of time measurements. Traditional solutions attempt to improve accuracy by optimizing satellite timing or employing fiber-optic synchronization technology. However, the former is limited by physical limitations and cannot exceed the hundreds of nanoseconds level, while the latter is prohibitively expensive and unsuitable for long-distance transmission scenarios in the field, thus failing to meet the demands of refined O&M. Summary of the Invention

[0007] In order to overcome the shortcomings of the existing technology, a high-precision distributed fault location method, device and system for transmission line are proposed.

[0008] A high-precision distributed fault location method for a transmission line, the high-precision distributed fault location method for a transmission line being applied to a monitoring terminal deployed at each node of the transmission line, comprising:

[0009] Obtaining a traveling wave signal, the traveling wave signal corresponding to the traveling wave current when a fault point of the transmission line occurs;

[0010] At the time point when the traveling wave signal arrives, the 1PPS signal of the Beidou satellite and the local OCXO clock signal of the current monitoring terminal are obtained, and the first time difference between the rising edges of the two is measured; the phase difference is calculated based on the first time difference, and an absolute timestamp in nanoseconds is obtained through a reconstruction algorithm;

[0011] Measuring a second time difference between the 1PPS signal of the Beidou satellite and the traveling wave signal arriving at the current monitoring terminal;

[0012] The absolute timestamp and the second time difference are transmitted to a backend fault diagnosis center server to calculate a specific fault location.

[0013] A high-precision distributed fault location device for power transmission lines. The high-precision distributed fault location device for power transmission lines is deployed at each node of the power transmission line and includes an MCU main control unit and a time-to-digital converter electrically connected to the MCU main control unit. The time-to-digital converter is used to capture traveling wave signals, 1PPS signals from Beidou satellites, and the local OCXO clock signal of the current high-precision distributed fault location device for power transmission lines.

[0014] Preferably, the time-to-digital converter is a dual-channel time-to-digital converter, and includes a first time-to-digital converter and a second time-to-digital converter;

[0015] The 1PPS signal of the Beidou satellite and the local OCXO clock signal are respectively connected to the start pin and stop pin of the first time-to-digital converter; the traveling wave signal is connected to the start pin of the second time-to-digital converter, and the 1PPS signal of the Beidou satellite is also connected to the stop pin of the second time-to-digital converter.

[0016] Preferably, the dual-channel time-to-digital converter is connected to the MCU main control unit via an SPI interface.

[0017] Preferably, it also includes a CAT1 4G communication unit electrically connected to the MCU main control unit, and the CAT1 4G communication unit is used to communicate with a preset background fault diagnosis center server.

[0018] Preferably, it also includes a communication unit energy acquisition module and an energy storage module electrically connected to the MCU main control unit; the energy acquisition module includes an AC induction power acquisition unit and a solar panel, and is used to obtain electrical energy; the energy storage module includes a lithium battery and a charge and discharge protection circuit corresponding to the lithium battery.

[0019] Preferably, it also includes a Beidou timing module electrically connected to the MCU main control unit, and the Beidou timing module is used to provide the 1PPS signal of the Beidou satellite.

[0020] Preferably, it also includes a current and voltage acquisition module electrically connected to the MCU main control unit, and the current and voltage acquisition module is used to obtain one or more of traveling wave current, hidden danger current, power frequency current, and power frequency voltage.

[0021] Preferably, it also includes an encryption module electrically connected to the MCU main control unit, and the encryption module is used to encrypt the time information and sensor information that need to be uploaded to the preset background fault diagnosis center server.

[0022] Preferably, it also includes an ambient temperature and humidity acquisition module and / or a wire temperature measurement module electrically connected to the MCU main control unit; the ambient temperature and humidity acquisition module includes a temperature and humidity probe; the wire temperature measurement module includes a wire temperature measurement sensor.

[0023] A high-precision distributed fault location system for power transmission lines includes a preset background fault diagnosis center server and multiple high-precision distributed fault location devices for power transmission lines as described above; the high-precision distributed fault location devices for power transmission lines are deployed at each node of the power transmission line and communicate with the preset background fault diagnosis center server through a network.

[0024] The high-precision distributed fault location device and system for power transmission lines provided by the present invention are based on a distributed fault diagnosis method. By integrating a high-precision time-to-digital converter (TDC) into the fault location device deployed at each node, the TDC is used to directly measure the phase difference between the 1PPS signal and the local OCXO clock signal. The MCU main control unit then runs a corresponding algorithm to obtain the phase difference between the two and thus obtain the time reference. At the same time, this solution uses TDC hardware to compare the dual-channel time difference to delay, which improves the accuracy of traditional software threshold judgment by more than 100 times. In terms of data transmission, this solution only needs to return the fault timestamp, without returning the complete waveform.

[0025] Compared with existing technologies, this solution achieves a time base acquisition error of less than 10ns, greatly reducing the failure rate of data transmission. Furthermore, when the Beidou timing chip signal is abnormal and unable to provide timing, this solution provides OCXO dynamic taming and punctuality (72-hour drift <10ns) to ensure stable equipment operation, meeting not only high-precision requirements but also refined operation and maintenance needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a framework diagram of a high-precision distributed fault location system for power transmission lines according to an embodiment of the present invention;

[0027] Figure 2 This is a framework diagram of a high-precision distributed fault location device for power transmission lines according to an embodiment of the present invention;

[0028] Figure 3 Schematic diagram of the working framework of a high-precision distributed fault location device and system for power transmission lines in an embodiment of the present invention. DETAILED DESCRIPTION

[0029] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0030] A high-precision distributed fault location method for a transmission line is provided. The method is applied to a monitoring terminal deployed at each node of the transmission line, comprising the following steps:

[0031] S1, obtaining a traveling wave signal, which corresponds to the traveling wave current when a fault occurs on the transmission line;

[0032] S2, when the traveling wave signal arrives, obtain the 1PPS signal of the BeiDou satellite and the local OCXO clock signal of the current monitoring terminal, and measure the first time difference between the rising edges of the two;

[0033] S3, calculates the phase difference based on the first time difference, and obtains the absolute timestamp in nanoseconds through the reconstruction algorithm;

[0034] S4, measuring the second time difference between the Beidou satellite 1PPS signal and the traveling wave signal arriving at the current monitoring terminal;

[0035] S5, transmitting the absolute timestamp and the second time difference to the backend fault diagnosis center server to calculate the specific fault location.

[0036] Among them, the traveling wave signal is when a short circuit, line break, lightning strike or other fault occurs in the transmission line, and the line impedance suddenly changes at the fault point, resulting in instantaneous and drastic changes in voltage and current, forming a high-frequency transient signal / traveling wave current.

[0037] Specifically, through a distributed installation approach, two sets of equipment (high-precision distributed fault location devices for transmission lines) can monitor a range of up to 30 km. For long-distance transmission lines, one set is deployed every 30 km. For monitoring distances less than 30 km, one set is deployed at each end, eliminating the need for installation on every tower. When a transmission line experiences a fault such as a short circuit, line break, or lightning strike, the line impedance suddenly changes at the fault point, causing dramatic, instantaneous changes in voltage and current, generating a high-frequency transient signal (traveling wave current). This sudden change is equivalent to injecting an equivalent high-frequency voltage source into both sides of the line at the fault point, triggering rapid charge migration and electromagnetic field transients. Devices on both sides of the fault point calibrate the time at which the traveling wave current is detected. Software algorithms then calculate the distance to the fault point, enabling highly accurate fault location.

[0038] The accuracy of distributed positioning essentially depends on the time measurement resolution. High-precision time measurement resolution can be achieved through a high-precision time-to-digital converter (TDC), with the resolution reaching up to the picosecond level (for example, the TDC7200 can reach 55 picoseconds).

[0039] By connecting the nanosecond-level 1PPS signal in the Beidou timing module and the local OCXO clock to a high-precision time-to-digital converter, the time difference Δt between the rising edges of the two is measured. The MCU main control unit then reads and calculates the phase difference Δφ = 2π ×f × Δt, where f is the local OCXO clock frequency. The absolute time t=N*T is then reconstructed through an algorithm. OCXO *+(Δφ / 2π)*T OCXO (where N is the OCXO clock cycle count, T OCXO The Beidou timing module uses a time base of only 100 nm (where Δφ is the phase difference between the Beidou 1PPS signal and the local OCXO clock period) to obtain a nanosecond absolute timestamp. The Beidou timing module's nanosecond-level 1PPS signal and the traveling wave signal are then connected to another measurement channel of a high-precision time-to-digital converter (TDC). This allows for a time difference of less than 1 ns, minimizing the delay of MCU software interrupts. The measurement error depends solely on the TDC resolution (<0.1 ns). In this scenario, Beidou only provides the time reference, and if Beidou fails, the OCXO's autonomous timing error is less than 1 ns / minute, mitigating the signal instability issues associated with Beidou timing modules in mountainous areas. When a traveling wave occurs on the line, the MCU main control unit uses the TDC-reconstructed nanosecond absolute timestamp and the time difference between the arrival of the traveling wave current and the rising edge of the 1PPS signal. After encryption, the 4G communication unit transmits this to the backend fault diagnosis center server to calculate the specific fault location.

[0040] Based on the above-mentioned high-precision transmission line distributed fault location device method, a high-precision transmission line distributed fault location device and system are provided, such as Figures 1 to 2As shown, the high-precision transmission line distributed fault location system includes a pre-set background fault diagnosis center server and multiple high-precision transmission line distributed fault location devices deployed at each node of the transmission line; the high-precision transmission line distributed fault location device communicates with the preset background fault diagnosis center server through the network.

[0041] The high-precision distributed fault location device for power transmission lines serves as a monitoring terminal. It includes an MCU (main control unit) and a time-to-digital converter (TDC) electrically connected to the MCU. The TDC captures traveling wave signals, the 1PPS signal from the Beidou satellite, and the local OCXO clock signal of the device. The MCU, which utilizes an ARM microcontroller (MCU) with an M4 core, runs algorithms to determine the phase difference between the 1PPS and the local OCXO clock, records the arrival time of the traveling wave signal, and communicates with other modules and sensors. The TDC directly measures the time difference between the 1PPS signal and the local OCXO clock. Software-based algorithms then reconstruct the phase difference and nanosecond time, generating a nanosecond-level time base and determining the arrival time of the traveling wave current. This eliminates traveling wave detection delays and overcomes the limitations of the original manufacturer's interface.

[0042] Furthermore, the time-to-digital converter is a dual-channel time-to-digital converter, comprising a first time-to-digital converter and a second time-to-digital converter. The Beidou satellite's 1PPS signal and the local OCXO clock signal are connected to the first time-to-digital converter's start and stop pins, respectively. The traveling wave signal is connected to the second time-to-digital converter's start pin, and the Beidou satellite's 1PPS signal is also connected to the second time-to-digital converter's stop pin. The dual-channel time-to-digital converter is connected to the MCU main control unit via an SPI interface.

[0043] Assume that the first time-to-digital converter is TDC1 and the second time-to-digital converter is TDC2; the 1PPS signal is connected to the start pin of the TDC1 channel, and the local OCXO clock is connected to the stop pin of the TDC1 channel; the output pin of the traveling wave current signal is connected to the start pin of the TDC2 channel, and the 1PPS signal of the Beidou satellite is obtained through the timing module and output to the stop pin of the TDC 2 channel; the entire TDC is connected to the MCU via the SPI pin.

[0044] Among them, the dual-channel TDC hardware compares the arrival time difference between the traveling wave and 1PPS to avoid MCU software delay; the dynamically tamed OCXO achieves long-term timekeeping after Beidou loses lock, making the 72-hour drift less than 10ns.

[0045] The high-precision distributed fault location device for power transmission lines also integrates an energy acquisition module, an energy storage module, a timing module, a current and voltage acquisition module, an ambient temperature and humidity acquisition module, a conductor temperature measurement module, an encryption module and a CAT1 4G communication unit.

[0046] Specifically, the energy acquisition module is composed of a high-efficiency AC induction power acquisition unit and a solar panel. It is used to sense electrical energy from the AC transmission line in real time to power and charge the monitoring terminal, ensuring that the equipment has sufficient power and is online 24 hours a day.

[0047] The energy storage module consists of a large-capacity lithium battery and a corresponding charge-discharge protection circuit. It is used to store the remaining energy after the energy acquisition module supplies power to the monitoring terminal, and to power the monitoring terminal when the line is out of power or the energy acquisition module cannot sense enough energy, to ensure stable power supply for the equipment and not overcharge or overdischarge.

[0048] The timing module is a high-precision single Beidou timing module, which is connected to the MCU main control unit through the UART interface and is used to provide a 1PPS signal with an accuracy of less than or equal to 10ns.

[0049] The ambient temperature and humidity acquisition module includes a temperature and humidity probe with a maximum accuracy of ±0.2°C and ±4%RH, and uses a highly reliable I2C to communicate with the MCU main control unit.

[0050] The current and voltage acquisition module is used to obtain real-time traveling wave current, hidden danger current, power frequency current and power frequency voltage data, and transmit them to the data processing unit for analysis in real time, so as to promptly discover and solve potential problems and hidden dangers and ensure the safe and stable operation of the power system.

[0051] The conductor temperature measurement module has the function of real-time conductor surface temperature measurement, providing real-time data support for areas such as dynamic line capacity expansion, line tension clamp heating monitoring, and line DC ice melting.

[0052] The encryption module is connected to the MCU via the SPI bus. Hardware encryption prevents device data from being eavesdropped or tampered with. When frequently exchanging positioning data, hardware encryption implements bidirectional node identity authentication and packet integrity verification, preventing attackers from forging nodes and disrupting the fault location algorithm's three-dimensional coordinate calculations.

[0053] The CAT1 4G communication unit supports dual-SIM single standby and is connected to the MCU main control unit via the UART interface, allowing the terminal to transmit fault timestamps back via 4G signals.

[0054] The above is an explanation of the present invention to help understand the present invention; however, the implementation of the present invention is not limited to the above embodiments, and any changes, modifications, substitutions, combinations, and simplifications made without departing from the principles of the present invention should be considered equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A high-precision distributed fault location method for power transmission lines, characterized in that: The high-precision distributed fault location method for transmission lines is applied to monitoring terminals deployed at each node of the transmission line, and includes: Obtaining a traveling wave signal, the traveling wave signal corresponding to the traveling wave current when a fault point of the transmission line occurs; At the time point when the traveling wave signal arrives, the 1PPS signal of the Beidou satellite and the local OCXO clock signal of the current monitoring terminal are obtained, and the first time difference between the rising edges of the two is measured; the phase difference is calculated based on the first time difference, and an absolute timestamp in nanoseconds is obtained through a reconstruction algorithm; Measuring a second time difference between the 1PPS signal of the Beidou satellite and the traveling wave signal arriving at the current monitoring terminal; The absolute timestamp and the second time difference are transmitted to a backend fault diagnosis center server to calculate a specific fault location.

2. A high-precision distributed fault location device for power transmission lines, characterized in that: The high-precision distributed fault location device for a transmission line is used to implement the high-precision distributed fault location method for a transmission line as described in claim 1, and includes an MCU main control unit and a time-to-digital converter electrically connected to the MCU main control unit; the time-to-digital converter is used to capture traveling wave signals, the 1PPS signal of the Beidou satellite, and the local OCXO clock signal of the current high-precision distributed fault location device for a transmission line.

3. The high-precision distributed fault location device for power transmission lines according to claim 1, characterized in that: The time-to-digital converter is a dual-channel time-to-digital converter, and includes a first time-to-digital converter and a second time-to-digital converter; The 1PPS signal of the Beidou satellite and the local OCXO clock signal are respectively connected to the start pin and stop pin of the first time-to-digital converter; the traveling wave signal is connected to the start pin of the second time-to-digital converter, and the 1PPS signal of the Beidou satellite is also connected to the stop pin of the second time-to-digital converter.

4. The high-precision distributed fault location device for power transmission lines according to claim 3, characterized in that: The dual-channel time-to-digital converter is connected to the MCU main control unit via an SPI interface.

5. The high-precision distributed fault location device for power transmission lines according to any one of claims 2 to 4, characterized in that: It also includes a CAT1 4G communication unit electrically connected to the MCU main control unit, and the CAT1 4G communication unit is used to communicate with a preset background fault diagnosis center server.

6. The high-precision distributed fault location device for power transmission lines according to claim 5, characterized in that: It also includes a communication unit energy acquisition module and an energy storage module electrically connected to the MCU main control unit; the energy acquisition module includes an AC induction power acquisition unit and a solar panel, and is used to obtain electrical energy; the energy storage module includes a lithium battery and a charge and discharge protection circuit corresponding to the lithium battery.

7. The high-precision distributed fault location device for power transmission lines according to claim 5, characterized in that: It also includes a Beidou timing module electrically connected to the MCU main control unit, and the Beidou timing module is used to provide the 1PPS signal of the Beidou satellite.

8. The high-precision distributed fault location device for power transmission lines according to claim 5, characterized in that: It also includes a current and voltage acquisition module electrically connected to the MCU main control unit, and the current and voltage acquisition module is used to obtain one or more of traveling wave current, hidden danger current, power frequency current, and power frequency voltage.

9. The high-precision distributed fault location device for power transmission lines according to claim 5, characterized in that: Also included is an encryption module electrically connected to the MCU main control unit, the encryption module for uploading the time information and sensor information required to the preset background fault diagnosis center server to encrypt processing; It also includes an ambient temperature and humidity acquisition module and / or a wire temperature measurement module electrically connected to the MCU main control unit; the ambient temperature and humidity acquisition module includes a temperature and humidity probe; the wire temperature measurement module includes a wire temperature measurement sensor.

10. A high-precision distributed fault location system for power transmission lines, characterized in that: It includes a preset background fault diagnosis center server and multiple high-precision transmission line distributed fault locating devices as described in any one of claims 2 to 9; the high-precision transmission line distributed fault locating devices are deployed on each node of the transmission line and perform network communication with the preset background fault diagnosis center server.

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