Power distribution automation device of synchronous phasor measurement type and power distribution implementation method

Abstract

The application provides a power distribution automation device and a power distribution implementation method, and relates to the technical field of power distribution automation.The device comprises a circuit board, which is divided into a core board, a main board, an analog signal measurement board, a liquid crystal screen adapter board, a key control display board, a power module, a residual voltage board, a power voltage measurement switching board, an indicator light board and a PMU board.The application also comprises a power distribution implementation method, which realizes wide-area synchronization, high frequency and high-precision sampling functions;the FXU ground detection performance is significantly improved, the neighborhood protection is realized without relying on the main station, the precise positioning, isolation and second-level self-healing of faults are automatically completed;the distributed intelligent FA function realizes the absolute selectivity of protection without relying on the main station and the level difference cooperation of the main line, accurately completes the minimum isolation of the fault section and the second-level recovery of power supply of the non-fault section;the neighborhood protection makes up for the selectivity defects of the overcurrent protection and can trip the upstream and downstream switches of the fault point.

Description

Technical Field

[0001] This invention relates to the field of power distribution automation technology, specifically to a synchronous phasor measurement type power distribution automation device and power distribution implementation method. Background Technology

[0002] With the development of social productivity and industrial production, the requirements for power grid reliability are getting higher and higher. The large-scale application of photovoltaic power generation has also changed the traditional single-source power supply structure of distribution networks. The development of technologies such as the Internet of Things, artificial intelligence, and big data has made automated fault handling in the power grid field possible. There is an urgent need for a new type of distribution automation device with high-precision, large-scale synchronous power grid monitoring, fast and accurate fault identification, isolation, and self-healing capabilities to match the requirements of the new power grid, while providing data accumulation for fault handling based on artificial intelligence and big data automation.

[0003] The existing distribution network mainly adopts the FTU feeder automation protection device of the distribution automation master station. It realizes the automation protection of the distribution network based on the traditional three-stage overcurrent protection + reclosing mechanism. It has remote signaling, remote control and remote measurement functions. It has high requirements for the communication quality and processing capability of the automation master station. Its protection strategy relies on the master station's time synchronization and centralized analysis. The setting is complicated, which can easily lead to over-level tripping. The fault isolation time is long, the single-phase grounding identification accuracy is low, and it cannot achieve large-scale synchronous monitoring and strategy control.

[0004] The existing FTU feeder automation protection device consists of a circuit breaker body, power supply voltage transformer, voltage transformer / sensor, current transformer / sensor, FTU controller, connecting cables, etc.

[0005] Primarily based on centralized protection logic of the main station, its system structure is as follows: Figure 1 As shown, for typical overcurrent and ground fault types in the power grid, automated protection is achieved by setting different overcurrent / ground fault protection values ​​plus time delays for upstream and downstream FTUs. In the event of a fault, multiple reclosing is used for fault isolation.

[0006] The automatic protection process for its feeder is as follows:

[0007] The first step is to initiate fault handling.

[0008] Upon receiving the first fault current signal, the real-time server initiates the fault analysis preprocessing procedure. After a set delay (the duration can be configured), it collects all fault signals and switch tripping signals along the feeder, waiting for the circuit breakers along the line to complete their reclosing operations. After the signal collection cycle ends, it analyzes the collected signals, deleting erroneous signals such as those indicating the switch is closed or reporting overcurrent even though no trip was reported. It then determines whether to begin the fault handling process based on the following conditions. If no corresponding tripping change information is found, the analysis and recovery operation is stopped.

[0009] A trip must be accompanied by a corresponding fault signal; otherwise, the fault analysis will be ignored.

[0010] The second step is to identify the last faulty component (switch) on the faulty feeder (along the power supply path before the fault). The area below this switch is the fault zone. If there is only one fault signal, the fault zone must be outside this point. If there are multiple fault signals, the search will determine the last one in the power supply direction before the fault. To ensure the safety of the process, multi-branch faults (different branches of the same feeder reporting unrelated overcurrent signals, in which case the last overcurrent switch cannot be identified) will directly exit the automatic analysis process, and corresponding system events will be generated to alert the user.

[0011] The third step is to determine the nature of the fault.

[0012] The nature of the fault can be determined by whether its location is directly connected to the busbar. If it is directly connected to the busbar (without going through a disconnector), the fault is likely in the ring main unit or switch station (busbar). If the fault is not directly connected to the busbar, determine whether it is a load fault or a line fault.

[0013] The fault area should be a closed area enclosed by several switches (including the switch where the end-of-line overcurrent signal is located) and their points within the fault area. Starting from the identified end-of-line fault overcurrent location, search downwards (in the power supply direction) for switches that collect overcurrent signals. If found, this point is a boundary point. If a switch or disconnector in the "off" state is encountered, it is also added to the queue as a boundary point.

[0014] Step 5: Isolate the fault.

[0015] Fault isolation is based on the previously identified fault areas, combining and separating them, keeping the separation unchanged, and providing the operation steps for disconnecting them sequentially, and calculating the total power outage capacity within the fault area.

[0016] Step 6: Restore power to the non-faulty sections. This operation involves two steps.

[0017] (1) Restore power supply to the main power supply section (the fault has been isolated). At this time, set the relevant components in the trip list (this step is not required if the tripping component is an end overcurrent component).

[0018] (2) Restore the recoverable area below the fault point. This part requires first calculating whether the candidate points of each recoverable area have sufficient capacity, then dividing the fault area into segments according to the situation, and repeating the calculation. Finally, a scheme for closing the circuit breaker and restoring power supply is given, including the restoration of multiple sub-areas.

[0019] Traditional centralized feeder protection requires high-quality communication channels and a computer master station, resulting in significant investment and a wide and complex engineering scope. In particular, the settings are complex, which can easily lead to cascading trips. During the reclosing process, the line experiences multiple high-load impacts, and the fault isolation time is relatively long. Summary of the Invention

[0020] The technical problem to be solved by the present invention is to provide a synchronous phasor measurement type power distribution automation device and power distribution implementation method to overcome the shortcomings of the prior art described in the background.

[0021] To solve the above-mentioned technical problems, embodiments of the present invention provide the following technical solution: a synchronous phasor measurement type power distribution automation device; including a circuit board, the circuit board being divided into a core board, a main board, a data acquisition board, an analog signal sampling board, a key control display board, a power module, a residual voltage board, a power supply voltage measurement switching board, an indicator light board, and a PMU module;

[0022] The core board circuit includes a main control chip, a FLASH chip, SRAM, an RTC circuit, an encryption chip, a 24C02 memory, a temperature measurement circuit, and a parallel port driver circuit. The core board's interfaces include I2C communication, SPI communication, UART communication, parallel port communication, and I / O interfaces.

[0023] The motherboard includes a core board interface, a system power supply circuit, a switch remote control circuit, a switch remote signaling circuit, a power module remote control and signaling circuit, energy storage current, operating current, battery voltage, and operating voltage measurement circuits, a communication network port, a maintenance network port, a 4G module serial communication port, a PMU communication serial port, one reserved 232 communication interface and one reserved serial communication port, an external indicator light driver circuit, and the motherboard is connected to the key control display board via a soft connection.

[0024] The motherboard and the analog signal sampling board are connected by a flexible flat cable, which provides 5V power to the analog signal sampling board. The analog signal sampling board sends voltage and current measurement signals to the AD7616 interface of the motherboard via the flexible flat cable. The motherboard also includes a line loss module driver circuit, a frequency measurement circuit, a GPS, a Bluetooth circuit, and a communication interface circuit for the PMU module.

[0025] The acquisition board includes a primary voltage measurement circuit, a secondary voltage measurement circuit, a primary current measurement circuit, and a zero-voltage-zero-current measurement circuit. The primary voltage measurement circuit is compatible with electromagnetic FTU voltage measurement input, and the primary current measurement circuit is compatible with electromagnetic FTU current measurement input. The primary voltage measurement circuit, secondary voltage measurement circuit, primary current measurement circuit, and zero-voltage-zero-current measurement circuit are all electromagnetic acquisition transformers. The voltage and current measurement signals output by the electromagnetic acquisition transformers are sent to the operational amplifier follower circuit. The follower circuit splits each measurement signal into two mutually independent measurement signals, which are then sent to the main board and the PMU module respectively via flexible flat cables.

[0026] The acquisition board also includes a ±15V power supply circuit. The 5V power supply from the motherboard is sent to the Mornsun A0515S-1WR3 power module, and the ±15V power supply output by the module provides operating power for the op amplifiers on the board.

[0027] The power module is structurally compatible with both electromagnetic power modules and capacitor-powered power modules.

[0028] The residual pressure plate has an interface compatible with electromagnetic FTUs, electronic FTUs, and deeply integrated FTUs.

[0029] The PMU module, based on BeiDou synchronization technology, uses 12.8KHz high-frequency sampling and 0.5-level measurement accuracy to continuously sample and record the current and voltage at the measurement points, and marks each sampling point with a time tag that is synchronized with the world standard time UTC with an accuracy of 1μs.

[0030] Preferably, the PMU module includes:

[0031] The BeiDou / GPS module is used to provide high-precision time synchronization and geographic location information;

[0032] The AD conversion module is used to convert analog power grid signals into high-precision digital signals;

[0033] The vector measurement module is used to measure the synchronous phasor, frequency, and rate of change of frequency of the power grid.

[0034] The data communication unit is used to transmit measurement data to the master station or other terminals in real time.

[0035] Preferably, the power supply voltage measurement switching board adopts an independent module design, and the circuit is divided into an AC 220V voltage measurement circuit and a two-way power supply switching circuit.

[0036] Preferably, the key control display board includes an LCD screen adapter board, a 4G module communication interface, a maintenance serial port interface, a maintenance network port interface, a remote / local switch, a fault enable / disable switch, a centralized / local switch, and LCD screen function buttons.

[0037] A power distribution implementation method, employing any one of the aforementioned synchronous phasor measurement type power distribution automation devices, for realizing single-phase grounding identification and protection, includes the following steps:

[0038] Step S1: Collect zero-sequence current data from each monitoring point on the line, and synchronize the timestamps based on BeiDou / GPS time synchronization.

[0039] Step S2: Classify the fault type based on the magnitude of the zero-sequence current I0:

[0040] Strong characteristic fault: I0≥3A, adopting an improved transient power direction protection algorithm, and combining local voltage and current phase difference to determine the fault direction;

[0041] Weak characteristic fault: 1A≤I0<3A, obtain the zero-sequence current waveform data of adjacent terminals through neighborhood protection, calculate the waveform similarity and comprehensively determine the fault section;

[0042] Extremely weak characteristic fault: I0<1A, based on waveform similarity analysis of multi-point synchronous zero-sequence current data, the grounding section is determined;

[0043] Step S3: For faults with strong characteristics, an adaptive threshold adjustment zero-sequence overcurrent algorithm is used to dynamically optimize the protection action threshold.

[0044] Step S4: For weak and extremely weak characteristic faults, generate protection output action commands, drive the circuit breaker to isolate the fault section, and upload the fault waveform and location results to the main station.

[0045] Preferably, the improved transient power direction protection algorithm in step S2 includes: extracting the zero-sequence voltage and current transient components within 1 / 4 cycle after the fault, and calculating the instantaneous power direction; if the power direction continues to reverse and the duration is ≥5ms, it is determined to be an in-zone fault, specifically:

[0046] Using db4 wavelet to analyze zero-sequence voltage Perform a 3-level decomposition and calculate the modulus maxima of detail coefficients at each scale. When the modulus maxima at a certain scale exceeds 3... Determine the start time of the fault ;in, Let be the instantaneous value of the zero-sequence voltage at time t. This represents the standard deviation of zero-sequence voltage noise during normal operation.

[0047] extract Zero-sequence voltage within the time window and zero-sequence current Transient components are separated using a 4th-order Butterworth high-pass filter. and ,in: Let be the instantaneous value of the zero-sequence current at time t. It is the transient zero-sequence voltage component. This is the transient zero-sequence current component;

[0048] Calculate instantaneous power Define the power direction function:

[0049]

[0050] This indicates the power direction determination result at time t;

[0051] Statistics within a 10ms sliding time window Duration of =-1 If both conditions are met ≥5ms and If the value is greater than 0.5A, it is determined to be a fault within the zone; among which, This represents the duration of the power direction reversal.

[0052] Preferably, the waveform similarity calculation in step S2 includes:

[0053] Normalize the zero-sequence current waveforms of adjacent terminals; extract the zero-sequence current waveform data of adjacent terminals within one cycle after the fault occurs, and define:

[0054] This represents the instantaneous value of the zero-sequence current of the i-th terminal at the n-th sampling point;

[0055] This represents the instantaneous value of the zero-sequence current of the j-th terminal adjacent to terminal i at the n-th sampling point;

[0056] N is the total number of sampling points collected for each terminal, with a value of 128.

[0057] The waveform is preprocessed, and the waveform mean is calculated. Remove the DC component;

[0058] After normalization, we get The amplitude is scaled to the range of [-1, 1].

[0059] Similarity was calculated using the cross-correlation coefficient method.

[0060]

[0061] in:

[0062] , is the mean of the normalized waveform;

[0063] When there is a sampling delay, the Dynamic Time Warping (DTW) algorithm is used:

[0064]

[0065] in, The endpoint values ​​of the cumulative distance matrix are obtained through dynamic programming.

[0066] is the normalization factor, and the similarity range is [0, 1].

[0067] Calculate the waveform similarity between poles for adjacent terminals m, n, and k distributed along the line.

[0068] If rod m and rod n are similar ≥0.9, and the similarity between rod n and rod k is... If the value is ≤0.2, then the fault is determined to be located between rod n and rod k.

[0069] Preferably, step S3 employs an adaptive threshold adjustment zero-sequence overcurrent algorithm to dynamically optimize the protection action threshold, specifically as follows:

[0070] Real-time acquisition of zero-sequence current after a strong characteristic fault occurs Data, sampling frequency not less than 1000Hz;

[0071] Calculate the maximum value of the zero-sequence current within one power frequency cycle. ,average value and zero-sequence current change rate ,in The sampling interval;

[0072] Using formula Calculate the dynamic protection action threshold ,in, , , Let be the weighting coefficient, satisfying + + =1, and dynamically adjusted according to the time t after the fault occurs: 50ms before the fault occurs = 0.6, = 0.3, = 0.1; 50ms after the fault occurs, the weighting coefficient is adjusted in real time according to the fluctuation of the zero-sequence current.

[0073] Preferably, it also includes implementing automated protection for the feeder, the specific steps of which are as follows:

[0074] Step S1: Each feeder terminal monitors the line current / voltage in real time. If a fault characteristic is detected and the neighbor protection activation threshold is reached, the neighbor protection logic is triggered.

[0075] Step S2: The feeder terminal where the fault point is located collects the fault status of neighboring feeder terminals through neighborhood communication, and determines the fault status based on the 4G communication delay T. 4G-L With local protection action time T LPL Neighborhood protection action time T NPL Reclosing time T ER The relationship allows for dynamic selection of protection action modes:

[0076] Case 1: If T NPL <T 4G-L <T LPL If the fault occurs, the neighborhood protection will be activated, and the upstream neighboring switches of the fault point will be quickly tripped, while the branch switches will have time to operate.

[0077] Case 2: If T LPL <T 4G-L < T ER If the circuit breaker fails, the local protection will trip and verify the correctness of the tripping through neighborhood communication before reclosing. If an error occurs, error correction closing will be triggered.

[0078] Case 3: If T 4G-L ≥ T ER If communication is interrupted, the system switches to local protection logic and performs the tripping operation independently.

[0079] Among them, the status of the adjacent feeder terminal is checked before reclosing. If this switch is not upstream of the fault, the opening command is cancelled and the closing delay time is ≤100ms.

[0080] Step S3: When a non-faulty feeder terminal detects the neighbor protection start threshold but has no local fault, it immediately sends a no-fault status to the adjacent feeder terminal to assist in the judgment of the faulty section.

[0081] Step S4: Based on the fault location results, drive the upstream switch to open and isolate the fault, and drive the downstream switch to close and restore power supply, and upload the event log to the main station.

[0082] Preferably, the fault segment judgment logic in step S2 includes: if feeder terminal m detects a fault and feeder terminal n has no fault, then the fault is located between feeder terminal m and feeder terminal n; if both feeder terminal m and feeder terminal n report a fault, then the fault is located in the downstream segment of feeder terminal n.

[0083] The beneficial effects of the above-described technical solution of the present invention are as follows:

[0084] 1) Achieve wide-area synchronous, high-frequency, and high-precision sampling functions:

[0085] The clock synchronization accuracy of all FXU device measurement data is achieved to 1μs using the BeiDou time synchronization second pulse signal. The terminal sampling frequency is no less than 12.8kHz, that is, no less than 256 sampling points are sampled synchronously per cycle. High-precision synchronous sampling data can effectively improve the accuracy of fault diagnosis.

[0086] 2) Improved FXU grounding detection performance:

[0087] Based on the zero-sequence current method and the zero-sequence power direction method, a multi-point fault waveform comparison algorithm based on neighborhood communication is added. At the time of the fault occurrence, the upstream and downstream adjacent terminals of the fault point exchange data. While comparing the state variables, the similarity comparison of the waveforms at multiple points at the time of the fault is performed simultaneously. Based on the comparison of the current and voltage data at multiple points and the waveform similarity, the grounding fault is comprehensively judged, and the single-phase grounding fault with a grounding current ≥1A can be accurately judged.

[0088] 3) Achieve neighborhood protection independent of the master station, automatically completing accurate fault location, isolation, and second-level self-healing:

[0089] The neighborhood protection function based on 4G wireless communication utilizes synchronized line status / current / voltage data from adjacent terminals to detect faults within a designated area (including the protection zone between the current switch and the adjacent downstream switch, and the FA zone between the current switch and the adjacent upstream switch). This enables fault location and isolation, achieving intelligent distributed feeder automation (FA). The distributed intelligent FA function achieves absolute selectivity for protection without relying on the master station or the main line differential coordination, accurately minimizing the isolation of faulty sections and restoring power to non-faulty sections within seconds. Neighborhood protection compensates for the selectivity deficiencies of overcurrent protection, allowing for the immediate tripping of upstream and downstream switches at the fault location. Attached Figure Description

[0090] Figure 1 This is a schematic diagram of the structure of a fully automated FA system in the existing technology.

[0091] Figure 2 This is a circuit diagram of the power distribution automation circuit device of the present invention;

[0092] Figure 3 This is a basic functional block diagram of the wide-area synchronous measurement unit of the present invention;

[0093] Figure 4 This is an example diagram of the single-phase grounding protection identification method of the present invention;

[0094] Figure 5 This is an example effect diagram of the single-phase grounding protection identification method of the present invention. Detailed Implementation

[0095] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0096] The assembly structure of the device of the present invention is as follows:

[0097] The device features a double-door structure. The first door serves to seal the exterior of the enclosure, with a sealing strip on the inside and a lightning bolt symbol, product name, and manufacturer's logo silkscreened on the outside.

[0098] The second door serves as the mounting panel for the operation buttons and display screen. It houses a 2.4-inch OLED display screen, LCD function operation buttons, a power start / stop button, function status indicator lights, a protection plate, a power switch, and manual opening / closing control buttons. An acrylic baffle is installed on the inside of the second door where the display screen will be located. The display content is viewed through the baffle from the outside of the second door; this design effectively prevents electrostatic interference and damage to the display screen from hard objects.

[0099] The aviation connectors (network connectors, power connectors, current connectors, and 14-pin connectors) adopt an independent mounting plate design, and the functional requirements can be added or removed by individually changing the connector board according to different project needs.

[0100] Antenna Installation: The FXU includes a GPS / BDS antenna on the motherboard, a 4G antenna on the main station communication module, a 4G antenna on the PMU module, and a GPS / BDS antenna on the PMU module. The antennas are delivered to the outside of the chassis via a waterproof lock at the bottom. The 4G antenna is fixed to the bottom of the chassis using a mounting bracket. The GPS antenna is a magnetic antenna; after the chassis is installed on-site, the GPS antenna is magnetically attached to the angle iron securing the chassis, with the receiving side facing directly upwards.

[0101] Indicator light installation: The indicator light board is installed on the inside of the bottom of the chassis and connected to the motherboard via a flexible ribbon cable; a lamp cover is installed at the indicator light hole position on the outside of the bottom of the chassis for waterproofing and anti-static purposes.

[0102] The motherboard, signal measurement board, power supply voltage measurement switching board, power module, and PMU module are designed as independently installable components. This part of the circuit can be pre-assembled and tested before being installed into the chassis, which improves assembly and testing efficiency.

[0103] The chassis has a pre-installed mounting position for the BDCU board, which will be installed according to project requirements. When installing the BDCU board, the aviation connector base plate must be replaced with one equipped with a waterproof lock and antenna mounting points. The two 4G antennas of the BDCU are routed to the outside of the chassis via the waterproof lock and secured to the aviation connector base plate at the bottom of the chassis.

[0104] like Figure 2 As shown, the circuit structure of the synchronous phasor measurement type power distribution automation device of the present invention is as follows:

[0105] Circuit board: The circuit board is divided into core board, motherboard, acquisition board, key display board, power module, residual voltage board, power voltage measurement switching board, indicator board and PMU module (which can also be expanded with BDCU board).

[0106] Core Board: The core board circuitry includes a main control chip, FLASH chip, SRAM, RTC circuit, encryption chip, 24C02 memory, temperature measurement circuit, and parallel port driver circuit. The core board's interfaces include I2C communication, SPI communication, UART communication, parallel port communication, and I / O interfaces.

[0107] Mainboard: The mainboard circuitry includes the core board interface, system power supply circuit, switch remote control circuit, switch remote signaling circuit, power module remote control and signaling circuit, energy storage current, operating current, battery voltage, and operating voltage measurement circuits, two network communication circuits (communication port and maintenance port), 4G module serial communication, PMU communication serial port, one reserved RS-232 communication interface and one reserved serial communication interface (the reserved communication interface is extended from the core board's SPI3 via the WK2132 chip), and external indicator light driver circuitry. The mainboard is connected to the keypad display board via a soft connection.

[0108] The motherboard and the analog signal sampling board are connected via a flexible flat cable, which provides 5V power to the analog signal sampling board. The sampling board sends voltage and current measurement signals to the AD7616 interface on the motherboard via the flexible flat cable. The motherboard also includes a line loss module driver circuit, a frequency measurement circuit, GPS, Bluetooth circuit, and a communication interface circuit for the PMU module.

[0109] Data Acquisition Board: The data acquisition board includes a primary voltage measurement circuit, a secondary voltage measurement circuit, a primary current measurement circuit, and a zero-voltage, zero-current measurement circuit. The primary voltage measurement circuit is compatible with electromagnetic FTU voltage measurement input; the primary current measurement circuit is compatible with electromagnetic FTU current measurement input. The PCB packages of electromagnetic data acquisition transformers and electronic and deeply integrated data acquisition transformers are designed for compatibility.

[0110] The voltage and current measurement signals output by the current transformer are sent to the operational amplifier follower circuit. The follower circuit splits each measurement signal into two mutually independent measurement signals, which are then sent to the main board and the PMU module respectively via flexible flat cables.

[0111] The acquisition board also includes a ±15V power supply circuit. The 5V power supply from the motherboard is sent to the Mornsun A0515S-1WR3 power module, and the ±15V power output from the module provides operating power for the op-amps on the board.

[0112] Keyboard Display Panel: The keyboard display panel includes an LCD screen adapter board, a 4G module communication interface (DB9 port), a maintenance serial port interface, a maintenance network port interface, remote and local switches, fault enable / disable switches, centralized and local switches, and LCD screen function buttons. As needed, in addition to the six standardized indicator lights for "Power," "Communication Status," "Self-Test Fault," "Routine Protection," "Local FA," and "Centralized FA," eight new indicator lights are added: "Separate Position Remote Signaling," "Closed Position Remote Signaling," "Energy Storage Remote Signaling," "Interlock," "Operation," "Overcurrent Alarm," "Zero Current Alarm," and "Grounding Alarm."

[0113] Power Module: The structure is compatible with both electromagnetic and capacitor-powered power modules. Power modules are purchased externally. The motherboard power and control interfaces are designed for functional compatibility, allowing for the selection of different models and manufacturers of power modules based on project requirements.

[0114] Residual pressure board: The residual pressure board interface is compatible with electromagnetic FTU, electronic FTU and deep integration FTU.

[0115] Power supply voltage measurement switching board: It adopts an independent module design, and the circuit is divided into an AC 220V voltage measurement circuit and a two-way power switching circuit (electromagnetic type).

[0116] The circuit board packaging adopts a compatible structure of capacitor power tapping measurement board (deep integration) and power supply voltage measurement switching board (electromagnetic type);

[0117] The power supply voltage, after passing through the current transformer (the capacitor power supply of the deeply integrated FTU uses an isolated operational amplifier to measure the voltage input), is sent to the voltage follower. The follower splits the signal into two independent measurement signals, which are then sent to the signal interfaces with the motherboard and the PMU module. Simultaneously, the motherboard sends 5V power to the power supply voltage measurement switching board via a flexible flat cable. The DC chip converts +5V to -5V, providing ±5V power to the voltage follower.

[0118] PMU module: Based on BeiDou synchronization technology, it adopts high-frequency sampling of 12.8KHz and 0.5-level measurement accuracy to continuously sample and record the current and voltage at the measurement points, and marks each sampling point with a time tag with a synchronization accuracy of 1μs with the world standard time UTC.

[0119] In this embodiment, the PMU module includes:

[0120] The BeiDou / GPS module is used to provide high-precision time synchronization and geographic location information;

[0121] The AD conversion module is used to convert analog power grid signals into high-precision digital signals;

[0122] The vector measurement module is used to measure the synchronous phasor, frequency, and rate of change of frequency of the power grid.

[0123] The data communication unit is used to transmit measurement data to the master station or other terminals in real time.

[0124] The PMU features high-precision, wide-range synchronous sampling, specifically: It integrates a BeiDou high-precision synchronization module and a wireless lateral communication module within the distribution network feeder automation terminal, enabling devices installed at any location on the line to accurately synchronize with BeiDou satellite time. The time difference between the BeiDou second pulse and the sampling pulse is ≤1μs, the error in fundamental voltage phase angle measurement is ≤0.2°, and the error in fundamental current phase measurement is ≤0.5°. It also has waveform recording capabilities, with waveform recording time stamp accuracy using GPS or BeiDou time stamps. Under rated values, the waveform recording error for zero-sequence voltage and zero-sequence current is no greater than 10µs, and the waveform recording error for the same measurement channel across different terminals is no greater than 10µs.

[0125] Meanwhile, high bandwidth, high precision, and high frequency sampling are also key technologies for wide-area synchronous measurement devices for distribution networks. Grounding algorithms and neighborhood protection algorithms are deployed in the wide-area synchronous measurement unit to achieve rapid and accurate switch operation.

[0126] The synchronous phasor measurement type power distribution automation device is based on BeiDou high-precision synchronization technology, supporting high-frequency sampling of 12.8KHz and 0.5-level measurement accuracy, continuously sampling and recording the current and voltage at the measurement points. Simultaneously, utilizing a built-in BeiDou satellite navigation module and its unique algorithm, each sampling point is labeled with a time stamp synchronized with Coordinated Universal Time (UTC) with an accuracy of 1μs, achieving high-precision neighborhood synchronization data acquisition and ensuring the accuracy and reliability of fault diagnosis results.

[0127] By using the PMU and BeiDou synchronized clock, comprehensive and accurate monitoring of the power grid can be carried out over a wide area, enabling full-scale visualized management of the distribution network.

[0128] In this embodiment, the key control display board includes an LCD screen adapter board, a 4G module communication interface, a maintenance serial port interface, a maintenance network port interface, a remote / local switch, a fault enable / disable switch, a centralized / local switch, and LCD screen function buttons.

[0129] A power distribution implementation method, employing any one of the aforementioned synchronous phasor measurement type power distribution automation devices, for realizing single-phase grounding identification and protection, includes the following steps:

[0130] Step S1: Collect zero-sequence current data from each monitoring point on the line, and synchronize the timestamps based on BeiDou / GPS time synchronization.

[0131] Step S2: Classify the fault type based on the magnitude of the zero-sequence current I0:

[0132] Strong characteristic fault: I0≥3A, adopting an improved transient power direction protection algorithm, and combining local voltage and current phase difference to determine the fault direction;

[0133] Weak characteristic fault: 1A≤I0<3A, obtain the zero-sequence current waveform data of adjacent terminals through neighborhood protection, calculate the waveform similarity and comprehensively determine the fault section;

[0134] Extremely weak characteristic fault: I0<1A, based on waveform similarity analysis of multi-point synchronous zero-sequence current data, the grounding section is determined;

[0135] Step S3: For faults with strong characteristics, an adaptive threshold adjustment zero-sequence overcurrent algorithm is used to dynamically optimize the protection action threshold.

[0136] Step S4: For weak and extremely weak characteristic faults, generate protection output action commands, drive the circuit breaker to isolate the fault section, and upload the fault waveform and location results to the main station.

[0137] In this embodiment, the improved transient power direction protection algorithm in step S2 includes: extracting the zero-sequence voltage and current transient components within 1 / 4 cycle after the fault, and calculating the instantaneous power direction; if the power direction continues to reverse and the duration is ≥5ms, it is determined to be an in-zone fault, specifically:

[0138] Using db4 wavelet to analyze zero-sequence voltage Perform a 3-level decomposition and calculate the modulus maxima of detail coefficients at each scale. When the modulus maxima at a certain scale exceeds 3... Determine the start time of the fault ;in, Let be the instantaneous value of the zero-sequence voltage at time t. This represents the standard deviation of zero-sequence voltage noise during normal operation.

[0139] extract Zero-sequence voltage within the time window and zero-sequence current Transient components are separated using a 4th-order Butterworth high-pass filter. and ,in: Let be the instantaneous value of the zero-sequence current at time t. It is the transient zero-sequence voltage component. This is the transient zero-sequence current component;

[0140] Calculate instantaneous power Define the power direction function:

[0141]

[0142] This indicates the power direction determination result at time t;

[0143] Statistics within a 10ms sliding time window Duration of =-1 If both conditions are met ≥5ms and If the value is greater than 0.5A, it is determined to be a fault within the zone; among which, This represents the duration of the power direction reversal.

[0144] In this embodiment, the waveform similarity calculation in step S2 includes:

[0145] Normalize the zero-sequence current waveforms of adjacent terminals; extract the zero-sequence current waveform data of adjacent terminals within one cycle after the fault occurs, and define:

[0146] This represents the instantaneous value of the zero-sequence current of the i-th terminal at the n-th sampling point;

[0147] This represents the instantaneous value of the zero-sequence current of the j-th terminal adjacent to terminal i at the n-th sampling point;

[0148] N is the total number of sampling points collected for each terminal, with a value of 128.

[0149] The waveform is preprocessed, and the waveform mean is calculated. Remove the DC component;

[0150] After normalization, we get The amplitude is scaled to the range of [-1, 1].

[0151] Similarity was calculated using the cross-correlation coefficient method.

[0152]

[0153] in:

[0154] , is the mean of the normalized waveform;

[0155] When there is a sampling delay, the Dynamic Time Warping (DTW) algorithm is used:

[0156]

[0157] in, The endpoint values ​​of the cumulative distance matrix are obtained through dynamic programming.

[0158] is the normalization factor, and the similarity range is [0, 1].

[0159] Calculate the waveform similarity between poles for adjacent terminals m, n, and k distributed along the line.

[0160] If rod m and rod n are similar ≥0.9, and the similarity between rod n and rod k is... If the value is ≤0.2, then the fault is determined to be located between rod n and rod k.

[0161] In this embodiment, step S3 employs an adaptive threshold adjustment zero-sequence overcurrent algorithm to dynamically optimize the protection action threshold, specifically as follows:

[0162] Real-time acquisition of zero-sequence current after a strong characteristic fault occurs Data, sampling frequency not less than 1000Hz;

[0163] Calculate the maximum value of the zero-sequence current within one power frequency cycle. ,average value and zero-sequence current change rate ,in The sampling interval;

[0164] Using formula Calculate the dynamic protection action threshold ,in, , , Let be the weighting coefficient, satisfying + + =1, and dynamically adjusted according to the time t after the fault occurs: 50ms before the fault occurs = 0.6, = 0.3, = 0.1; 50ms after the fault occurs, the weighting coefficient is adjusted in real time according to the fluctuation of the zero-sequence current.

[0165] The specific methods for identifying and protecting single-phase grounding are as follows:

[0166] Based on the zero-sequence overcurrent, phase current asymmetry method, and zero-sequence power direction method, a multi-point zero-sequence current waveform comparison method based on domain communication is introduced to effectively improve the accuracy of ground fault identification with weak features and achieve 100% false alarm-free identification rate for ground faults with zero-sequence current above 1A.

[0167] For single-phase ground faults with strong characteristics (zero current > 3A, adjustable parameters), the local power directional protection utilizes local measurement data and an improved transient power directional protection algorithm based on massive field data to accurately detect single-phase ground faults. Simultaneously, the zero-sequence overcurrent algorithm based on adaptive threshold adjustment overcomes the threshold setting difficulties of traditional schemes, and is used to reflect the increasingly frequent complex ground faults involving interphase ground short circuits across different lines.

[0168] For single-phase ground faults with weak characteristics (zero current < 3A, parameters adjustable), the neighbor protection can improve protection sensitivity by making comprehensive judgments based on the obtained voltage and current data of adjacent terminals, accurately determine ground faults with zero-sequence current not less than 1A within the protected area, and complete the protection output action.

[0169] When the grounding current is as small as close to the inherent measurement error of the equipment, the influence of the error cannot be eliminated based on single-point data. Instead, it can be judged based on multi-point synchronous zero-sequence current data.

[0170] like Figure 4 , Figure 5 As shown, in a grounding test at a certain location with a "12,000Ω" current, 3I_0 < 1A, making it impossible to locate the fault based on single-point data. The zero-sequence current similarity between poles 1 and 2 is close to 1, while the similarity between poles 2 and 3 is -1 to 0. Based on this, it can be determined that the grounding section is between poles 2 and 3.

[0171] This embodiment also includes implementing automated protection for the feeder, the specific steps of which are as follows:

[0172] Step S1: Each feeder terminal monitors the line current / voltage in real time. If a fault characteristic is detected and the neighbor protection activation threshold is reached, the neighbor protection logic is triggered.

[0173] Step S2: The feeder terminal where the fault point is located collects the fault status of neighboring feeder terminals through neighborhood communication, and determines the fault status based on the 4G communication delay T. 4G-L With local protection action time T LPL Neighborhood protection action time T NPL Reclosing time T ER The relationship allows for dynamic selection of protection action modes:

[0174] Case 1: If T NPL <T 4G-L <T LPL If the fault occurs, the neighborhood protection will be activated, and the upstream neighboring switches of the fault point will be quickly tripped, while the branch switches will have time to operate.

[0175] Case 2: If T LPL <T 4G-L < T ER If the circuit breaker fails, the local protection will trip and verify the correctness of the tripping through neighborhood communication before reclosing. If an error occurs, error correction closing will be triggered.

[0176] Case 3: If T 4G-L ≥ T ER If communication is interrupted, the system switches to local protection logic and performs the tripping operation independently.

[0177] Among them, the status of the adjacent feeder terminal is checked before reclosing. If this switch is not upstream of the fault, the opening command is cancelled and the closing delay time is ≤100ms.

[0178] Step S3: When a non-faulty feeder terminal detects the neighbor protection start threshold but has no local fault, it immediately sends a no-fault status to the adjacent feeder terminal to assist in the judgment of the faulty section.

[0179] Step S4: Based on the fault location results, drive the upstream switch to open and isolate the fault, and drive the downstream switch to close and restore power supply, and upload the event log to the main station.

[0180] In this embodiment, the fault segment judgment logic in step S2 includes: if feeder terminal m detects a fault and feeder terminal n has no fault, then the fault is located between feeder terminal m and feeder terminal n; if both feeder terminal m and feeder terminal n report a fault, then the fault is located in the downstream segment of feeder terminal n.

[0181] The FA protection method is as follows:

[0182] When a fault occurs, the feeder automation terminal (FXU) interacts with adjacent terminals via 4G to detect faults that occur within the protection zone between adjacent terminals.

[0183] The system features high sampling synchronization accuracy, high sampling rate, and high sampling precision, enabling it to achieve neighborhood protection based on 4G horizontal communication. It also integrates traditional fault judgment algorithms such as local zero-sequence power directional protection to accurately determine whether a fault is within the protection area. It has absolute selectivity and automatically implements tripping of upstream and downstream fault points, isolates faulty sections, and performs subsequent self-healing control.

[0184] The realization of neighborhood protection depends on two important factors: low-latency communication between the beginning and end of the section and synchronous data measurement at each point. The former ensures short protection action time, while the latter is the basis for calculating current difference. Since neither fiber optic communication nor 5G communication is suitable for large-scale application in overhead power distribution lines for their respective reasons, this device organically combines 4G neighborhood protection with local overcurrent protection and automatic reclosing.

[0185] The core of the distributed intelligent protection and control technology based on 4G communication is the exchange of electrical quantity data between adjacent switches via 4G lateral communication. The current differential element built into the switch calculates the longitudinal current difference to determine whether the fault is within the switch's protection area, and the result is absolutely selective. Due to the potentially long delay of 4G communication, for phase-to-phase short-circuit faults, neighborhood protection cannot reliably serve as the main protection and needs to be combined with local overcurrent protection to adaptively apply either neighborhood protection or overcurrent protection to clear the fault.

[0186] For phase-to-phase short-circuit faults, the terminal completes the entire protection group's operation within 150ms based on 4G, realizing a distributed fast-acting FA (Automatic Facilitator), and clears the fault before the substation outlet circuit breaker protection (I-stage delay ≥ 200ms) operates. If the substation outlet circuit breaker overcurrent protection delay is short (I-stage delay ≤ 200ms) or the 4G communication time is long, a distributed slow-acting FA logic is used, clearing the fault after the outlet circuit breaker protection operates. For permanent faults, after clearing the upstream fault point, the terminal's neighbor protection isolates the fault section downstream and controls the tie switch to switch power, achieving self-healing within seconds.

[0187] During a short-circuit fault, the line voltage drops, so the downstream switch initiates operations such as waveform recording, fault diagnosis, and neighborhood communication based on the line voltage fluctuation. Upstream of the fault point, there is a fault current, so the upstream switch initiates operations directly based on the current fluctuation.

[0188] When a ground fault occurs, the zero-sequence voltage of the entire line will rise, so all switches will start recording, fault diagnosis, and neighborhood communication operations based on the zero-sequence voltage fluctuation.

[0189] When an FXU reaches the neighborhood protection activation threshold, it determines whether there is a short circuit or ground fault, collects the fault status of adjacent FXUs through neighborhood communication, analyzes the fault area, quickly trips the upstream neighboring switches of the fault point, and performs error correction and closing on other switches.

[0190] The fault is located between FXU1 and FXU2.

[0191] FXU1 detects a fault and receives a fault-free status from FXU2 via neighborhood communication. It determines that FXU1 falls within the neighborhood protection fault assessment range. Based on the neighborhood communication delay, the following three scenarios can be identified:

[0192] Case 1: T NPL <T 4G-L <T LPL ,

[0193] The neighbor protection action time is to allow time for the branch switch to operate;

[0194] Neighborhood communication latency is faster than local protection latency, so neighborhood protection initiates tripping operation.

[0195] Case 2: T LPL <T 4G-L < T ER ,

[0196] Neighborhood communication delay is slower than local protection, so local protection will activate the tripping operation first;

[0197] Before reclosing the switch, confirm via neighborhood communication that this switch is the upstream neighboring switch of the fault point and that the opening was correct.

[0198] Case 3: If T 4G-L ≥ T ER Or communication is interrupted.

[0199] Neighborhood protection is being phased out, and local protection is being adopted instead.

[0200] FXU2 reached the neighborhood protection activation threshold, but no fault was detected. It was determined that FXU2 was outside the neighborhood protection fault assessment boundary, and the fault status was immediately sent to FXU1 through neighborhood communication.

[0201] FXU3 reached the neighborhood protection activation threshold, but no fault was detected. It was determined that FXU3 was outside the neighborhood protection fault assessment boundary, and the fault status was immediately sent to FXU2 through neighborhood communication.

[0202] The fault is located between FXU2 and FXU3.

[0203] FXU1 detects a fault and receives the fault status of FXU2 through neighborhood communication. It determines that FXU1 belongs to the neighborhood protection fault assessment boundary. Based on the neighborhood communication delay, it can be divided into the following three cases:

[0204] Case 1: T NPL <T 4G-L <T LPL

[0205] The neighbor protection action time is to allow time for the branch switch to operate;

[0206] The neighbor communication delay is faster than the local protection. It is determined that the fault area is not between FXU1 and FXU2. The switch is in the closed state. The state is correct. The closed state is maintained.

[0207] Case 2: TLPL < T 4G-L <TER

[0208] Neighborhood communication delay is slower than local protection, so local protection will activate the tripping operation first;

[0209] Before reclosing the switch, confirm through neighborhood communication that this switch is not an upstream neighboring switch of the fault point, that the opening was incorrect, and then correct and close the switch.

[0210] Case 3: TER < T 4G-L Or communication interruption

[0211] Neighborhood protection is being phased out, and local protection is being adopted instead.

[0212] When FXU2 detects a fault, it receives the fault-free status of FXU3 through neighborhood communication and determines that FXU2 belongs to the fault judgment boundary of the neighborhood protection. For details of the protection logic, please refer to the FXU1 protection logic in "(I) The fault point is between FXU1 and FXU2". Simultaneously, the fault status is sent to FXU1 through neighborhood communication.

[0213] FXU3 reached the neighborhood protection activation threshold, but no fault was detected. It was determined that FXU3 was outside the neighborhood protection fault assessment boundary, and the fault status was immediately sent to FXU2 through neighborhood communication.

[0214] The beneficial effects of this invention include the following:

[0215] PMU high-precision full-network monitoring:

[0216] (1) By using the Beidou / GPS module, synchronous sampling and time synchronization are performed with Coordinated Universal Time (UTC) as the reference, so as to achieve synchronization between the terminal sampling pulse and the second pulse, and the synchronization error is ≤1µs;

[0217] (2) The measurement error limit for the fundamental current and voltage phase angle of the terminal is 0.2°;

[0218] (3) The terminal sampling frequency is above 12.8kHz, that is, more than 256 sampling points per cycle are used for synchronous sampling;

[0219] (4) The clock error of the waveform data time scale is no more than 10μs.

[0220] Single-phase grounding identification algorithm:

[0221] By introducing a multi-point zero-sequence current waveform comparison method based on domain communication, based on zero-sequence overcurrent, phase current asymmetry method, and zero-sequence power direction method, the accuracy of ground fault identification with weak features is effectively improved, and a 100% false alarm rate is achieved for ground fault identification with zero-sequence current above 1A.

[0222] Intelligent distributed FA and neighborhood communication:

[0223] (1) The terminal has a neighborhood protection function based on 4G wireless communication, which enables accurate judgment and rapid isolation of fault sections, with a minimum action delay of ≤200ms, and rapid power restoration of non-fault sections, realizing self-healing of distribution network lines;

[0224] (2) During a phase-to-phase short-circuit fault, the terminal implements adaptive handling based on the delay configuration of different protections of the outgoing line switches in the station, completes the distributed fast-acting FA and slow-acting FA over-processing logic respectively, correctly outputs the opening / closing signal, completes the isolation of the fault section and the restoration of power supply to the non-fault section, and has no false operation:

[0225] Fast-acting FA logic: The upstream sectionalizing switch trips to isolate the fault point, ensuring uninterrupted power supply to the upstream healthy area. The downstream sectionalizing switch automatically trips to isolate the faulty section, the tie switch closes to switch power supply back on, and power is restored to the downstream healthy area.

[0226] Slow-acting FA logic: When the outgoing line switch in the station trips to clear the fault, the upstream sectionalizing switch at the fault point operates to isolate the fault point, the outgoing line switch recloses successfully, and power supply is restored to the upstream healthy area. The downstream sectionalizing switch at the fault point automatically trips to isolate the faulty section, the tie switch closes to switch power supply, and power supply is restored to the downstream healthy area.

[0227] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A power distribution implementation method, characterized in that, To implement single-phase ground fault identification and protection, the following steps are included: Step S1: Collect zero-sequence current data from each monitoring point on the line, and synchronize the timestamps based on BeiDou / GPS time synchronization. Step S2: Classify the fault type based on the magnitude of the zero-sequence current I0: Strong characteristic fault: I0≥3A, adopting an improved transient power direction protection algorithm, and combining local voltage and current phase difference to determine the fault direction; Weak characteristic fault: 1A≤I0<3A, obtain the zero-sequence current waveform data of adjacent terminals through neighborhood protection, calculate the waveform similarity and comprehensively determine the fault section; Extremely weak characteristic fault: I0<1A, based on waveform similarity analysis of multi-point synchronous zero-sequence current data, the grounding section is determined; Step S3: For faults with strong characteristics, an adaptive threshold adjustment zero-sequence overcurrent algorithm is used to dynamically optimize the protection action threshold; specifically: Real-time acquisition of zero-sequence current after a strong characteristic fault occurs Data, sampling frequency not less than 1000Hz; Calculate the maximum value of the zero-sequence current within one power frequency cycle. ,average value and zero-sequence current change rate ,in The sampling interval; According to the maximum value ,average value Zero-sequence current change rate Calculate the dynamic protection action threshold ; Step S4: For weak and extremely weak characteristic faults, generate protection output action commands, drive the circuit breaker to isolate the fault section, and upload the fault waveform and location results to the main station.

2. The power distribution implementation method according to claim 1, characterized in that, The improved transient power direction protection algorithm in step S2 includes: extracting the zero-sequence voltage and current transient components within 1 / 4 cycle after the fault, and calculating the instantaneous power direction; if the power direction continues to reverse and the duration is ≥5ms, it is determined to be an in-zone fault, specifically: Using db4 wavelet to analyze zero-sequence voltage Perform a 3-level decomposition and calculate the modulus maxima of detail coefficients at each scale. When the modulus maxima at a certain scale exceeds 3... Determine the start time of the fault ;in, Let be the instantaneous value of the zero-sequence voltage at time t. This represents the standard deviation of zero-sequence voltage noise during normal operation. extract Zero-sequence voltage within the time window and zero-sequence current Transient components are separated using a 4th-order Butterworth high-pass filter. and ,in: Let be the instantaneous value of the zero-sequence current at time t. It is the transient zero-sequence voltage component. This is the transient zero-sequence current component; Calculate instantaneous power Define the power direction function: ； This indicates the power direction determination result at time t; Statistics within a 10ms sliding time window Duration of =-1 If both conditions are met ≥5ms and If the value is greater than 0.5A, it is determined to be a fault within the zone; among which, This represents the duration of the power direction reversal.

3. The power distribution implementation method according to claim 1, characterized in that, The waveform similarity calculation in step S2 includes: Normalize the zero-sequence current waveforms of adjacent terminals; extract the zero-sequence current waveform data of adjacent terminals within one cycle after the fault occurs, and define: This represents the instantaneous value of the zero-sequence current of the i-th terminal at the n-th sampling point; This represents the instantaneous value of the zero-sequence current of the j-th terminal adjacent to terminal i at the n-th sampling point; N is the total number of sampling points collected for each terminal, with a value of 128. The waveform is preprocessed, and the waveform mean is calculated. Remove the DC component; After normalization, we get The amplitude is scaled to the range of [-1, 1]. Similarity was calculated using the cross-correlation coefficient method. ； in: , is the mean of the normalized waveform; When there is a sampling delay, the Dynamic Time Warping (DTW) algorithm is used: ； in, The endpoint values ​​of the cumulative distance matrix are obtained through dynamic programming. is the normalization factor, and the similarity range is [0, 1]. Calculate the waveform similarity between poles for adjacent terminals m, n, and k distributed along the line. If rod m and rod n are similar ≥0.9, and the similarity between rod n and rod k is... If the value is ≤0.2, then the fault is determined to be located between rod n and rod k.

4. The power distribution implementation method according to claim 1, characterized in that, This also includes implementing automated protection for feeders, with the following specific steps: Step S1: Each feeder terminal monitors the line current / voltage in real time. If a fault characteristic is detected and the neighbor protection activation threshold is reached, the neighbor protection logic is triggered. Step S2: The feeder terminal where the fault point is located collects the fault status of neighboring feeder terminals through neighborhood communication, and determines the fault status based on the 4G communication delay T. 4G-L With local protection action time T LPL Neighborhood protection action time T NPL Reclosing time T ER The relationship allows for dynamic selection of protection action modes: Case 1: If T NPL <T 4G-L <T LPL If the fault occurs, the neighborhood protection will be activated, and the upstream neighboring switches of the fault point will be quickly tripped, while the branch switches will have time to operate. Case 2: If T LPL <T 4G-L < T ER If the circuit breaker fails, the local protection will trip and verify the correctness of the tripping through neighborhood communication before reclosing. If an error occurs, error correction closing will be triggered. Case 3: If T 4G-L ≥ T ER If communication is interrupted, the system switches to local protection logic and performs the tripping operation independently. Among them, the status of the adjacent feeder terminal is checked before reclosing. If this switch is not upstream of the fault, the opening command is cancelled and the closing delay time is ≤100ms. Step S3: When a non-faulty feeder terminal detects the neighbor protection start threshold but has no local fault, it immediately sends a no-fault status to the adjacent feeder terminal to assist in the judgment of the faulty section. Step S4: Based on the fault location results, drive the upstream switch to open and isolate the fault, and drive the downstream switch to close and restore power supply, and upload the event log to the main station.

5. A power distribution implementation method according to claim 3, characterized in that, The fault section judgment logic in step S2 includes: for adjacent terminals m, n, and k distributed along the line, if feeder terminal m detects a fault and feeder terminal n has no fault, then the fault is located between feeder terminal m and feeder terminal n; if both feeder terminal m and feeder terminal n report a fault, then the fault is located in the downstream section of feeder terminal n.

6. A synchronous phasor measurement type power distribution automation device for implementing the power distribution method of any one of claims 1-5, characterized in that, The circuit board includes a core board, motherboard, acquisition board, analog signal sampling board, key display board, power module, residual voltage board, power voltage measurement switching board, indicator board, and PMU module. The core board circuit includes a main control chip, a FLASH chip, SRAM, an RTC circuit, an encryption chip, a 24C02 memory, a temperature measurement circuit, and a parallel port driver circuit. The core board's interfaces include I2C communication, SPI communication, UART communication, parallel port communication, and I / O interfaces. The motherboard includes a core board interface, a system power supply circuit, a switch remote control circuit, a switch remote signaling circuit, a power module remote control and signaling circuit, energy storage current, operating current, battery voltage, and operating voltage measurement circuits, a communication network port, a maintenance network port, a 4G module serial communication port, a PMU communication serial port, one reserved 232 communication interface and one reserved serial communication port, an external indicator light driver circuit, and the motherboard is connected to the key control display board via a soft connection. The motherboard and the analog signal sampling board are connected by a flexible flat cable, which provides 5V power to the analog signal sampling board. The analog signal sampling board sends voltage and current measurement signals to the AD7616 interface of the motherboard via the flexible flat cable. The motherboard also includes a line loss module driver circuit, a frequency measurement circuit, a GPS, a Bluetooth circuit, and a communication interface circuit for the PMU module. The acquisition board includes a primary voltage measurement circuit, a secondary voltage measurement circuit, a primary current measurement circuit, and a zero-voltage-zero-current measurement circuit. The primary voltage measurement circuit is compatible with electromagnetic FTU voltage measurement input, and the primary current measurement circuit is compatible with electromagnetic FTU current measurement input. The primary voltage measurement circuit, secondary voltage measurement circuit, primary current measurement circuit, and zero-voltage-zero-current measurement circuit are all electromagnetic acquisition transformers. The voltage and current measurement signals output by the electromagnetic acquisition transformers are sent to the operational amplifier follower circuit. The follower circuit splits each measurement signal into two mutually independent measurement signals, which are then sent to the main board and the PMU module respectively via flexible flat cables. The acquisition board also includes a ±15V power supply circuit. The 5V power supply from the motherboard is sent to the Mornsun A0515S-1WR3 power module, and the ±15V power supply output by the module provides operating power for the op amplifiers on the board. The power module is structurally compatible with both electromagnetic power modules and capacitor-powered power modules. The residual pressure plate has an interface compatible with electromagnetic FTUs, electronic FTUs, and deeply integrated FTUs. The PMU module, based on BeiDou synchronization technology, uses 12.8KHz high-frequency sampling and 0.5-level measurement accuracy to continuously sample and record the current and voltage at the measurement points, and marks each sampling point with a time tag that is synchronized with the world standard time UTC with an accuracy of 1μs.

7. The synchronous phasor measurement type power distribution automation device according to claim 6, characterized in that, The PMU module includes: The BeiDou / GPS module is used to provide high-precision time synchronization and geographic location information; The AD conversion module is used to convert analog power grid signals into high-precision digital signals; The vector measurement module is used to measure the synchronous phasor, frequency, and rate of change of frequency of the power grid. The data communication unit is used to transmit measurement data to the master station or other terminals in real time.

8. The synchronous phasor measurement type power distribution automation device according to claim 6, characterized in that, The power supply voltage measurement switching board adopts an independent module design, and the circuit is divided into an AC 220V voltage measurement circuit and a two-way power supply switching circuit.

9. The synchronous phasor measurement type power distribution automation device according to claim 6, characterized in that, The key control display board includes an LCD screen adapter board, a 4G module communication interface, a maintenance serial port interface, a maintenance network port interface, a remote and local switch, a fault enable / disable switch, a centralized local switch, and LCD screen function buttons.

Images