Rural power distribution network multi-terminal differential protection method and system, controller and medium

Abstract

The invention discloses a rural power distribution network multi-terminal differential protection method and system, a controller and a medium, and relates to the technical field of power distribution network protection. The method comprises the steps that three-phase current signals of all nodes of the power distribution network are collected through a broadband synchronous sampling device, sampling data are obtained, and timestamps corresponding to the sampling data are recorded; preprocessing the sampled data, and aligning multi-terminal data timestamps; extracting a power frequency component and a high-frequency transient component of the preprocessed sampling data; calculating a differential criterion value according to the power frequency component and the high-frequency transient component; and according to the differential criterion value, identifying a fault, and processing the fault. According to the method, a power frequency component and a high-frequency transient component are combined to serve as a differential criterion, and the limitation of traditional power frequency protection on high-resistance fault sensitivity is broken through; through a satellite time service + PTP hybrid synchronization mechanism, the rural long line mu s-level synchronization precision is realized.

Description

Technical Field

[0001] The present invention relates to the technical field of distribution network protection, and in particular, to a multi-terminal differential protection method, system, controller and medium for rural distribution networks. Background Art

[0002] At present, the differential protection method for rural distribution networks has the following disadvantages: (1) The lines of rural distribution networks are long and have many branches. Traditional current differential protection is vulnerable to the influence of harmonic injection from distributed power sources and weak characteristics of high-resistance grounding faults, resulting in insufficient sensitivity.

[0003] (2) Existing synchronous sampling technologies are mostly designed for power frequency. The acquisition accuracy of broadband transient signals is insufficient, and the multi-terminal clock synchronization accuracy is difficult to meet the requirements of the μs level.

[0004] (3) In a hybrid communication environment, the data transmission delays are inconsistent, resulting in calculation errors of differential criteria. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art. For this purpose, the present invention provides a multi-terminal differential protection method, system, controller and medium for rural distribution networks, which can improve the detection sensitivity.

[0006] On the one hand, according to an embodiment of the present invention, a multi-terminal differential protection method for rural distribution networks includes the following steps: Collect three-phase current signals of each node of the distribution network through a broadband synchronous sampling device to obtain sampling data, and record the time stamp corresponding to the sampling data; Preprocess the sampling data to align the multi-terminal data time stamps; Extract the power frequency component and high-frequency transient component of the preprocessed sampling data; Calculate the differential criterion value according to the power frequency component and the high-frequency transient component; Identify a fault according to the differential criterion value and process the fault.

[0007] According to some embodiments of the present invention, the broadband synchronous sampling device includes a current sensor, a satellite timing module and a data preprocessing unit. The current sensor is used to collect three-phase current signals of each node. The satellite timing module is used to provide the time stamp corresponding to the sampling data. The data preprocessing unit is used to preprocess the sampling data, remove noise, perform Z-score normalization on the current amplitude, and align the multi-terminal data time stamps based on the PTP protocol. The data preprocessing unit is also used to extract the power frequency component and high-frequency transient component of the preprocessed sampling data.

[0008] According to some embodiments of the present invention, extracting the power frequency component and the high-frequency transient component of the preprocessed sampled data includes: Extracting the amplitude and phase of the power frequency component through fast Fourier transform to generate a fundamental wave current vector; Adopting Daubechies 4 wavelet packet decomposition to extract the high-frequency transient component of a preset sub-band.

[0009] According to some embodiments of the present invention, the fundamental wave current vector is expressed as: , where is the amplitude of the power frequency component, is the phase of the power frequency component; the high-frequency transient component is expressed as , where is the wavelet coefficient; the differential criterion value is expressed as: ; where and are dynamic coefficients.

[0010] According to some embodiments of the present invention, identifying a fault based on the differential criterion value and processing the fault includes: When the differential criterion value is less than or equal to 0, it is determined that there is no fault and it is normal; When the differential criterion value is greater than 0, it is determined that there is a fault, and the fault type is identified and the fault is processed.

[0011] According to some embodiments of the present invention, identifying the fault type and processing the fault includes: When the high-frequency transient component is greater than a first preset value and the amplitude of the power frequency component is less than a second preset value, the fault type is determined to be high-resistance grounding; When the amplitude of the power frequency component is greater than a third preset value, the fault type is determined to be a short-circuit fault; When there is a fault, a tripping command is sent to the corresponding circuit breaker, and the full waveform data before and after the fault is recorded.

[0012] According to some embodiments of the present invention, it further includes the step of dynamic parameter adjustment, specifically including: At every preset time period, based on the latest fault data, the values of the dynamic coefficients are adjusted through the particle swarm optimization algorithm; When it is detected that the distributed power penetration rate is greater than a fourth preset value, increase value.

[0013] On the other hand, the multi-terminal differential protection system for rural distribution networks according to the embodiments of the present invention includes a broadband synchronous sampling device, a communication network, and a differential protection master station. Among them, the broadband synchronous sampling device is used to collect three-phase current signals of each node of the distribution network, obtain sampling data, record the time stamps corresponding to the sampling data, and preprocess the sampling data to align the time stamps of multi-terminal data, and extract the power frequency components and high-frequency transient components of the preprocessed sampling data; the communication network is used for data transmission between the broadband synchronous sampling device and the differential protection master station; the differential protection master station is used to calculate the differential criterion value according to the power frequency component and the high-frequency transient component, identify faults according to the differential criterion value, and process the faults.

[0014] On the other hand, the controller according to the embodiments of the present invention includes at least one control processor and a memory for communicatively connecting with the at least one control processor; the memory stores instructions executable by the at least one control processor, and the instructions are executed by the at least one control processor to enable the at least one control processor to execute the above-mentioned multi-terminal differential protection method for rural distribution networks.

[0015] On the other hand, according to the embodiments of the present invention, a computer-readable storage medium stores computer-executable instructions for causing a computer to execute the above-mentioned multi-terminal differential protection method for rural distribution networks.

[0016] The multi-terminal differential protection method, system, controller, and medium for rural distribution networks according to the embodiments of the present invention have at least the following beneficial effects: By jointly using the power frequency component and the high-frequency transient component as the differential criterion, the sensitivity limitation of traditional power frequency protection for high-resistance faults is broken through, and the detection sensitivity is improved.

[0017] The additional aspects and advantages of the present invention will be partially given in the following description, partially become apparent from the following description, or be understood through the practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The above and / or additional aspects and advantages of the present invention will become apparent and easy to understand from the description of the embodiments in conjunction with the following drawings, where: Figure 1 is a flowchart of the steps of the multi-terminal differential protection method for rural distribution networks according to the embodiments of the present invention; Figure 2 is a schematic structural diagram of the multi-terminal differential protection system for rural distribution networks according to the embodiments of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0019] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, where like or similar reference numerals denote like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are only used to explain the present application, and should not be construed as a limitation to the present application. For the step numbers in the following embodiments, they are only set for the convenience of explanation and illustration, and no limitation is imposed on the order between the steps. The execution order of each step in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0020] In the description of the present invention, it should be understood that for the orientation description, such as the orientation or positional relationship indicated by up, down, front, back, left, right, etc. is based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention.

[0021] The terms "first", "second", "third", "fourth", etc. in the specification and claims of the present invention and the accompanying drawings are used to distinguish different objects, rather than to describe a specific order. In addition, the terms "comprising" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or device that includes a series of steps or units is not limited to the listed steps or units, but optionally further includes steps or units not listed, or optionally further includes other steps or units inherent to these processes, methods, products, or devices.

[0022] Referring to "embodiments" in the present invention means that specific features, structures, or characteristics described in connection with the embodiments can be included in at least one embodiment of the present invention. The phrase appearing in various positions in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment mutually exclusive with other embodiments. Those skilled in the art explicitly and implicitly understand that the embodiments described herein can be combined with other embodiments.

[0023] Currently, the differential protection method for rural distribution networks has the following disadvantages: (1) The lines of rural distribution networks are long and have many branches. Traditional current differential protection is vulnerable to the influence of harmonic injection from distributed power sources and weak characteristics of high-resistance grounding faults, resulting in insufficient sensitivity.

[0024] (2) Existing synchronous sampling technologies are mostly designed for power frequency, with insufficient acquisition accuracy for wide-frequency transient signals, and the multi-terminal clock synchronization accuracy is difficult to meet the requirements of the μs level.

[0025] (3) In a hybrid communication environment, the data transmission delays are inconsistent, resulting in calculation errors in differential criteria.

[0026] To this end, the embodiments of the present invention propose a multi-terminal differential protection method, system, controller, and medium for rural distribution networks. By using the joint of power frequency components and high-frequency transient components as the differential criterion, the sensitivity limitation of traditional power frequency protection for high-resistance faults is broken through; through the hybrid synchronization mechanism of satellite time synchronization + PTP, the microsecond-level synchronization accuracy of rural long lines is achieved.

[0027] The following will describe in detail the multi-terminal differential protection method, system, controller, and medium for rural distribution networks according to the embodiments of the present invention with reference to the accompanying drawings.

[0028] On the one hand, the embodiments of the present invention propose a multi-terminal differential protection method for rural distribution networks, as Figure 1 shown, the method includes but is not limited to steps S100 to S500.

[0029] Step S100: Collect three-phase current signals of each node in the distribution network through the broadband synchronous sampling device 100 to obtain sampling data, and record the time stamps corresponding to the sampling data; Specifically, in this example, broadband synchronous sampling devices 100 are deployed at each node in the distribution network to collect current signals in the frequency band of 0.1 - 2 kHz (or other frequency bands), and time synchronization of each node is achieved through GPS / Beidou dual-mode time synchronization and IEEE 1588 PTP protocol, with a synchronization error ≤ 1 μs.

[0030] Step S200: Preprocess the sampling data to align the time stamps of multi-terminal data; Specifically, the broadband synchronous sampling device 100 uses an adaptive filter to suppress noise (such as clutter other than 50 Hz power frequency interference); at the same time, Z-score normalization is performed on the current amplitude to eliminate the dimension difference; and the time stamps of multi-terminal data are aligned based on the PTP protocol.

[0031] Step S300: Extract the power frequency components and high-frequency transient components of the preprocessed sampling data; Specifically, the broadband synchronous sampling device 100 adopts a parallel filtering architecture based on FPGA to realize the separation of power frequency and high-frequency signals, so as to extract the power frequency components and high-frequency transient components.

[0032] Step S400: Calculate the differential criterion value according to the power frequency components and high-frequency transient components; Specifically, by using the joint of power frequency components and high-frequency transient components as the differential criterion, the sensitivity limitation of traditional power frequency protection for high-resistance faults is broken through.

[0033] Step S500: Identify the fault according to the differential criterion value and process the fault.

[0034] The multi-terminal differential protection method for rural distribution networks according to the embodiments of the present invention uses the combined power frequency component and high-frequency transient component as the differential criterion, breaking through the sensitivity limitation of traditional power frequency protection for high-resistance faults and improving the detection sensitivity; through the hybrid synchronization mechanism of satellite time synchronization + PTP, the microsecond-level synchronization accuracy of rural long lines is achieved.

[0035] In the embodiments of the present application, the above-mentioned multi-terminal differential protection method for rural distribution networks is applied to a multi-terminal differential protection system for rural distribution networks, such as Figure 2 shown, the system includes a broadband synchronous sampling device 100, a communication network 200, and a differential protection master station 300. The system adopts a three-level architecture of "edge - communication - master station" to realize real-time data acquisition, transmission, and decision-making for multi-terminal differential protection of rural distribution networks.

[0036] Edge side: Deploy a broadband synchronous sampling device 100 to complete data acquisition and preprocessing.

[0037] Communication layer: Deploy a communication network 200 that combines optical fiber and 5G to ensure low-latency and high-reliability transmission.

[0038] Master station side: A centralized processing platform that executes multi-terminal data fusion and protection logic.

[0039] In this example, the broadband synchronous sampling device 100 includes a current sensor, a satellite time synchronization module, and a data preprocessing unit. Among them, the current sensor can include: Rogowski coil (fundamental wave 0.1 - 1 kHz, accuracy ±0.2%), high-frequency Hall probe (transient 1 - 2 kHz, sampling rate 10 kHz), etc., and has a 16-bit ADC module, supporting synchronous sampling (three-phase current synchronous sampling). The satellite time synchronization module uses a GPS / Beidou dual-mode receiver (1PPS pulse, time error ≤ 100 ns) and adopts the IEEE 1588 PTP protocol stack (hardware timestamp recording). The data preprocessing unit has the following functions: Anti-aliasing filter (cutoff frequency 2.5 kHz); Power frequency component isolation (band-stop filter 50 Hz ± 5 Hz); Synchronous sampling: Align the sampling clocks of each node based on the PTP protocol (microsecond-level synchronization).

[0040] Output a data stream with timestamps.

[0041] Furthermore, in some embodiments of the present application, the above step S300: extracting the power frequency component and high-frequency transient component of the preprocessed sampling data includes the following two steps: Step S310: Extract the amplitude and phase of the power frequency component through fast Fourier transform to generate a fundamental wave current vector; Step S320: Use Daubechies 4 wavelet packet decomposition to extract the high-frequency transient components of the preset sub-band.

[0042] Specifically, the data preprocessing unit uses a parallel filtering architecture based on FPGA to separate power frequency and high-frequency signals, so as to extract power frequency components and high-frequency transient components. Fundamental wave extraction: Calculate the amplitude ( ) and phase (θ) of the power frequency component through fast Fourier transform (FFT). High-frequency decomposition: Use Daubechies 4 wavelet packet decomposition (the energy of the 2-10 kHz sub-band ). According to the amplitude and phase of the power frequency component, the fundamental wave current vector can be generated: ; The high-frequency transient component can be expressed as , where is the wavelet coefficient. The data output by the broadband synchronous sampling device 100 to the differential protection master station is a compressed data packet. Compression mode: Switch the compression mode (lossy / hybrid / lossless) according to BB and RR. Fundamental wave compression: Use the improved LZW algorithm (complex number splitting compression, compression ratio ≥ 60%). High-frequency compression: Wavelet coefficient threshold truncation (retain the first 30% energy sub-band). Timestamp compression: Golomb coding (Δt difference sequence). The format of the compressed data packet output by the broadband synchronous sampling device 100 is: [compression mode | fundamental wave data | high-frequency coefficient | encoded timestamp]. Communication protocol: MQTT or IEC101 (QoS = 1, ensure at least one delivery).

[0043] Further, in some embodiments of the present application, the communication network has an optical fiber channel and a 5G channel. The optical fiber channel is used to transmit the reference clock signal, and the 5G channel is used to transmit the sampled data. Specifically, the optical fiber channel has the following functions: transmitting PTP synchronization messages (Sync / Follow_Up / Delay_Resp); transmitting the configuration instructions issued by the differential protection master station to the broadband synchronous sampling device 100. The performance indicators of the optical fiber channel are: unidirectional delay ≤ 1 ms, jitter ≤ 10 μs, supporting ring topology, and redundant path switching time < 50 ms. The 5G channel has the following functions: transmitting the compressed feature data packets of the broadband synchronous sampling device 100 to the differential protection master station, and performing heartbeat detection between the broadband synchronous sampling devices 100 at each edge node and the differential protection master station. Optimization design: 1. Slicing technology: Allocating a dedicated network slice for differential protection (bandwidth guarantee ≥ 1 Mbps). 2. Dynamic bandwidth adaptation: Adjusting the compression mode according to BB (for example, enabling lossy compression when B < 1 Mbps). When it is found that the communication between a certain edge node and the master station is interrupted, the edge node starts local caching (storing the data of the last 10 seconds). When the master station detects a timeout, it switches to the data of the adjacent node to reconstruct the fault area. If the data verification fails: The master station sends a NACK instruction, and the edge node retransmits and temporarily increases the compression level (such as from hybrid to lossless).

[0044] After receiving the compressed data packets from the broadband synchronous sampling device, the differential protection master station first performs data reconstruction, including LZW decompression on the fundamental wave, reconstructing the high-frequency components through inverse wavelet transform, decoding the Δt sequence and accumulating to restore the absolute time, so as to align the timestamps. After data reconstruction, according to the power frequency component and the high-frequency transient component, calculate the differential criterion value. The specific calculation method is as follows: ; wherein, and are dynamic coefficients, which are dynamically adjusted according to the actual network topology. In this example, let = 1.2, = 0.8. It should be noted that and can also be set to other values according to the actual situation.

[0045] Further, in some embodiments of the present application, the above step S500: identifying a fault according to the differential criterion value and processing the fault includes the following two steps: Step S510: When the differential criterion value is less than or equal to 0, it is determined that there is no fault and it is normal; Step S520: When the differential criterion value is greater than 0, it is determined that there is a fault, and the fault type is identified and the fault is processed.

[0046] Specifically, when D > 0, it is determined that a fault exists and the fault handling process is entered; when D ≤ 0, it is determined to be normal and the data acquisition step is returned. When a fault exists, the fault type is identified and the fault is processed. Specifically, step S520 includes the following three steps: Step S521: When the high-frequency transient component is greater than the first preset value and the amplitude of the power frequency component is less than the second preset value, the fault type is determined to be high-resistance grounding; Step S522: When the amplitude of the power frequency component is greater than the third preset value, the fault type is determined to be a short-circuit fault; Step S523: When a fault exists, a trip command is sent to the corresponding circuit breaker, and the full-waveform data before and after the fault is recorded.

[0047] Specifically, in this example, the first preset value is , the second preset value is , and the third preset value is , where represents the rated fundamental current, and represents the maximum value of the high-frequency transient current; then when and , the fault type is a high-resistance grounding fault; when , a short-circuit fault exists. When a fault exists, a trip command is sent to the corresponding circuit breaker (operating time ≤ 30 ms), and the full-waveform data for 1 s before and after the fault is recorded for subsequent analysis.

[0048] Furthermore, in some embodiments of the present application, the multi-terminal differential protection method for rural distribution networks further includes a step of dynamically adjusting parameters, specifically including: At every preset time interval, based on the latest fault data, the value of the dynamic coefficient is adjusted through the particle swarm optimization algorithm; When it is detected that the distributed power source penetration rate is greater than the fourth preset value, increase value.

[0049] Specifically, in this example, every 24 hours (or other time intervals), the values of and will be finely adjusted based on the latest fault data through the incremental particle swarm optimization algorithm to maximize the fault recognition rate; if it is detected that the distributed power source penetration rate > 50%, automatically increase weight to improve the sensitivity of the high-frequency component.

[0050] Furthermore, in some embodiments of the present application, when the communication link of a certain node in the distribution network is interrupted, the differential criterion will be reconstructed based on the data of the remaining nodes, and a direction element will be introduced for fault section location.

[0051] Furthermore, in this application, time synchronization is performed based on the satellite timing module and the PTP protocol, including the following processes: 1. Master-slave clock initialization 1.1 Master clock configuration (master node): Connect to the GPS / Beidou dual-mode timing source to generate 1PPS (pulse per second) and ToD (time message).

[0052] Start the PTP protocol stack and set it to the Grandmaster mode with the highest priority.

[0053] 1.2 Slave clock configuration (slave node): Initialize the local crystal oscillator, set it to the Slave mode, and listen for the Announce message of the master clock.

[0054] Enable the hardware timestamp module (FPGA / PHY chip) with an accuracy of ≤100 ns.

[0055] 2. Synchronization message interaction process Timing steps (in chronological order):

[0056] 3. Delay and offset calculation Unidirectional transmission delay calculation: ; Assume that the two-way network path is symmetric to eliminate the influence of clock frequency deviation.

[0057] Slave clock offset correction: ; The slave clock adjusts the local time: .

[0058] 4. Hybrid network asymmetric compensation Scenario: There is a hybrid path of optical fiber (fixed delay) and 5G (dynamic delay) between the master and slave clocks.

[0059] 4.1 Fixed delay pre-calibration: The optical fiber segment delay dfiber is measured by OTDR (e.g., dfiber = 0.5 ms).

[0060] 4.2 Dynamic delay measurement: Regularly measure the RTT (Round-Trip Time) of the 5G link: ; where 、 、 、 The Sync / Delay_Req interaction timestamp for the 5G link.

[0061] 5. Exception Handling and Recovery 5.1 Sync Message Loss Detection: If the slave clock does not receive a message for 3 consecutive Sync cycles → trigger an alarm.

[0062] Switch to the local timekeeping mode (oscillator stability ±1 ms / hour).

[0063] 5.2 Master Clock Switching: If the master clock fails, the BMCA (Best Master Clock Algorithm) elects a new master clock (the node with the second-highest priority) within 5 seconds.

[0064] 5.3 Large Offset Handling: If the calculated |offset| > 10 μs, gradually correct it (each adjustment ≤ 1 μs) to avoid data disorder caused by time jumps.

[0065] According to the rural distribution network multi-terminal differential protection method and system of the embodiments of the present invention, by jointly using the power frequency component and the high-frequency transient component as the differential criterion, the sensitivity limitation of traditional power frequency protection for high-resistance faults is broken through; through the hybrid synchronization mechanism of satellite time synchronization + PTP, the μs-level synchronization accuracy of rural long lines is achieved. Through the wideband synchronous sampling device, multi-source clock synchronization compensation, and composite differential criterion, the problems of sensitivity and reliability of rural distribution network protection are solved. The measured fault detection time ≤ 25 ms, which is 40% shorter than the traditional method; the recognition accuracy for high-resistance grounding faults (transition resistance > 5000 Ω) ≥ 95%.

[0066] On the other hand, the embodiments of the present application also provide a controller, including: A processor, which can be implemented in ways such as a general-purpose central processing unit (CPU), a microprocessor, an application-specific integrated circuit (ASIC), or one or more integrated circuits, and is used to execute relevant programs to implement the technical solutions provided by the embodiments of the present application; The memory can be implemented in the form of a read-only memory (ROM), a static storage device, a dynamic storage device, or a random access memory (RAM), etc. The memory can store an operating system and other application programs. When implementing the technical solutions provided in the embodiments of this specification through software or firmware, the relevant program codes are stored in the memory and are called by the processor to execute the multi-terminal differential protection method for rural distribution networks in the embodiments of this application; The input / output interface is used to implement information input and output; The communication interface is used to implement communication and interaction between this device and other devices. Communication can be achieved through wired means (such as USB, network cable, etc.) or through wireless means (such as mobile network, WIFI, Bluetooth, etc.); The bus transmits information between the various components of the device (such as the processor, memory, input / output interface, and communication interface); Among them, the processor, memory, input / output interface, and communication interface are communicatively connected to each other inside the device through the bus.

[0067] The embodiments of this application also provide a storage medium. The storage medium is a computer-readable storage medium. This storage medium stores a computer program, and when the computer program is executed by a processor, it implements the above-mentioned multi-terminal differential protection method for rural distribution networks.

[0068] As a non-transitory computer-readable storage medium, the memory can be used to store non-transitory software programs and non-transitory computer-executable programs. In addition, the memory can include high-speed random access memory, and can also include non-transitory memory, such as at least one magnetic disk storage device, a flash memory device, or other non-transitory solid-state storage devices. In some embodiments, the memory optionally includes a memory remotely set relative to the processor, and these remote memories can be connected to the processor through a network. Examples of the above-mentioned network include but are not limited to the Internet, enterprise intranet, local area network, mobile communication network, and their combinations. The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated, and may be located in one place, or may be distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0069] Although specific embodiments are described herein, those of ordinary skill in the art will recognize that many other modifications or alternative embodiments are also within the scope of the present disclosure. For example, any one of the functions and / or processing capabilities described in connection with a particular device or component can be performed by any other device or component. Additionally, although various exemplary implementations and architectures have been described in accordance with embodiments of the present disclosure, those of ordinary skill in the art will recognize that many other modifications to the exemplary implementations and architectures described herein are also within the scope of the present disclosure.

[0070] Certain aspects of the present disclosure have been described above with reference to block diagrams and flowcharts of systems, methods, systems, and / or computer program products according to exemplary embodiments. It should be understood that one or more blocks in the block diagrams and flowcharts, and combinations of blocks in the block diagrams and flowcharts, can be implemented respectively by executing computer-executable program instructions. Similarly, according to some embodiments, some blocks in the block diagrams and flowcharts may not need to be executed in the order shown, or may not need to be executed at all. Additionally, additional components and / or operations beyond those shown in the blocks of the block diagrams and flowcharts may be present in certain embodiments.

[0071] Accordingly, the blocks in the block diagrams and flowcharts support combinations of means for performing the specified functions, combinations of elements or steps for performing the specified functions, and means for program instructions for performing the specified functions. It should also be understood that each block in the block diagrams and flowcharts, and combinations of blocks in the block diagrams and flowcharts, can be implemented by a special purpose hardware computer system that performs a particular function, element, or step, or by a combination of special purpose hardware and computer instructions.

[0072] The program modules, applications, etc. described herein may include one or more software components, including, for example, software objects, methods, data structures, etc. Each such software component may include computer-executable instructions that, in response to execution, cause at least a portion of the functions described herein (e.g., one or more operations of the exemplary methods described herein) to be performed.

[0073] Software components can be coded in any of a variety of programming languages. An exemplary programming language can be a low-level programming language, such as an assembly language associated with a particular hardware architecture and / or operating system platform. Software components that include assembly language instructions may need to be converted by an assembler into executable machine code before being executed by the hardware architecture and / or platform. Another exemplary programming language can be a higher-level programming language, which can be portable across multiple architectures. Software components that include a higher-level programming language may need to be converted by an interpreter or compiler into an intermediate representation before execution. Other examples of programming languages include, but are not limited to, macro languages, shell or command languages, job control languages, scripting languages, database query or search languages, or report writing languages. In one or more exemplary embodiments, software components that include instructions in one of the above examples of programming languages can be executed directly by an operating system or other software components without first being converted into another form.

[0074] Software components can be stored as files or other data storage constructs. Software components with similar types or related functions can be stored together in, for example, a particular directory, folder, or library. Software components can be static (e.g., pre-set or fixed) or dynamic (e.g., created or modified at execution time).

[0075] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments, and various changes can be made without departing from the spirit of the present invention within the scope of knowledge possessed by those of ordinary skill in the art.

Claims

1. A multi-terminal differential protection method for rural distribution networks, characterized in that, It includes the following steps: Collect three-phase current signals of each node in the distribution network through a broadband synchronous sampling device to obtain sampling data, and record the time stamp corresponding to the sampling data; Preprocess the sampling data to align the time stamps of multi-terminal data; Extract the power frequency component and high-frequency transient component of the preprocessed sampling data; Calculate the differential criterion value according to the power frequency component and the high-frequency transient component; Identify faults according to the differential criterion value and process the faults; Among them, the broadband synchronous sampling device includes a current sensor, a satellite timing module and a data preprocessing unit. The current sensor is used to collect three-phase current signals of each node. The satellite timing module is used to provide the time stamp corresponding to the sampling data. The data preprocessing unit is used to preprocess the sampling data, remove noise, perform Z-score standardization on the current amplitude, and align the time stamps of multi-terminal data based on the PTP protocol. The data preprocessing unit is also used to extract the power frequency component and the high-frequency transient component of the preprocessed sampling data.

2. The multi-terminal differential protection method for rural distribution network according to claim 1, characterized in that The extraction of the power frequency component and the high-frequency transient component of the preprocessed sampling data includes: Extract the amplitude and phase of the power frequency component through fast Fourier transform to generate a fundamental current vector; Use Daubechies 4 wavelet packet decomposition to extract the high-frequency transient component of the preset sub-band.

3. The multi-terminal differential protection method for rural distribution network according to claim 2, characterized in that, The fundamental wave current vector is expressed as: , where is the amplitude of the power frequency component, is the phase of the power frequency component; the high-frequency transient component is expressed as , where is the wavelet coefficient; the differential criterion value is expressed as: ； Among them, and are dynamic coefficients, and n is the total number of high-frequency transient components.

4. The multi-terminal differential protection method for rural distribution network according to claim 3, characterized in that, The identification of faults according to the differential criterion value and the processing of the faults include: When the differential criterion value is less than or equal to 0, it is determined to be normal without faults; When the differential criterion value is greater than 0, it is determined that there is a fault, and the fault type is identified and the fault is processed.

5. The multi-terminal differential protection method for rural distribution network according to claim 4, characterized in that The identification of the fault type and the processing of the fault include: When the high-frequency transient component is greater than the first preset value and the amplitude of the power frequency component is less than the second preset value, the fault type is determined to be high-resistance grounding; When the amplitude of the power frequency component is greater than the third preset value, the fault type is determined to be a short-circuit fault; When a fault occurs, send a tripping command to the corresponding circuit breaker and record the full waveform data before and after the fault.

6. The multi-terminal differential protection method for rural distribution network according to claim 3, characterized in that It also includes the step of dynamic parameter adjustment, specifically including: Every preset time period, based on the latest fault data, adjust the value of the dynamic coefficient through the particle swarm optimization algorithm; When it is detected that the distributed power penetration rate is greater than the fourth preset value, increase the value.

7. A multi-terminal differential protection system for rural distribution networks, characterized in that, It includes a broadband synchronous sampling device, a communication network and a differential protection master station. Among them, the broadband synchronous sampling device is used to collect three-phase current signals of each node in the distribution network to obtain sampling data, record the time stamp corresponding to the sampling data, preprocess the sampling data, align the time stamps of multi-terminal data, and extract the power frequency component and the high-frequency transient component of the preprocessed sampling data; the communication network is used for data transmission between the broadband synchronous sampling device and the differential protection master station; the differential protection master station is used to calculate the differential criterion value according to the power frequency component and the high-frequency transient component, identify faults according to the differential criterion value, and process the faults.

8. A controller, characterized in that, Comprising at least one control processor and a memory for communicatively connecting with the at least one control processor; the memory stores instructions executable by the at least one control processor, and the instructions are executed by the at least one control processor to enable the at least one control processor to execute the multi-terminal differential protection method for rural distribution network according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions for causing a computer to execute the multi-terminal differential protection method for rural distribution network according to any one of claims 1 to 6.

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