Multi-terminal differential protection method, system, controller and medium for rural distribution network

Abstract

The present invention discloses a multi-terminal differential protection method, system, controller, and medium for rural distribution networks, and relates to the field of distribution network protection technology. The method comprises: collecting three-phase current signals from each node of the distribution network through a broadband synchronous sampling device to obtain sampled data and record the timestamps corresponding to the sampled data; preprocessing the sampled data and aligning the timestamps of the multi-terminal data; extracting the power frequency component and high-frequency transient component of the preprocessed sampled data; calculating the differential criterion value based on the power frequency component and the high-frequency transient component; identifying the fault based on the differential criterion value and processing the fault. By using the power frequency component and the high-frequency transient component as the differential criterion, the method breaks through the sensitivity limit of traditional power frequency protection to high-resistance faults; and through a hybrid synchronization mechanism of satellite timing + PTP, it achieves μs-level synchronization accuracy for long rural lines.

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 a rural distribution network. Background Art

[0002] Currently, the differential protection method for rural distribution networks has the following disadvantages:

[0003] (1) Rural distribution networks have long lines and many branches. Traditional current differential protection is easily affected by the harmonic injection of distributed power sources and the weak characteristics of high-resistance grounding faults, resulting in insufficient sensitivity.

[0004] (2) Existing synchronous sampling technologies are mostly designed for industrial frequency, and the accuracy of broadband transient signal acquisition is insufficient. In addition, the multi-terminal clock synchronization accuracy is difficult to meet the μs level requirements.

[0005] (3) In a hybrid communication environment, inconsistent data transmission delays lead to errors in differential criterion calculations. Summary of the Invention

[0006] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention proposes a multi-terminal differential protection method, system, controller and medium for rural distribution networks, which can improve detection sensitivity.

[0007] On the one hand, a multi-terminal differential protection method for a rural distribution network according to an embodiment of the present invention includes the following steps:

[0008] The three-phase current signal of each node of the distribution network is collected by a broadband synchronous sampling device to obtain sampling data, and the timestamp corresponding to the sampling data is recorded;

[0009] Preprocessing the sampled data and aligning timestamps of multi-terminal data;

[0010] Extracting the power frequency component and high-frequency transient component of the pre-processed sampling data;

[0011] Calculating a differential criterion value according to the power frequency component and the high-frequency transient component;

[0012] According to the differential criterion value, a fault is identified and processed.

[0013] 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 the three-phase current signal of each node. The satellite timing module is used to provide a timestamp corresponding to the sampled data. The data preprocessing unit is used to preprocess the sampled data, remove noise, perform Z-score normalization on the current amplitude, and align multi-terminal data timestamps 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 sampled data.

[0014] 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:

[0015] The amplitude and phase of the power frequency component are extracted by fast Fourier transform to generate the fundamental current vector;

[0016] Daubechies 4 wavelet packet decomposition is used to extract the high-frequency transient components of the preset subband.

[0017] According to some embodiments of the present invention, the fundamental current vector is expressed as: ,in, is the amplitude of the power frequency component, is the phase of the power frequency component; the high-frequency transient component is expressed as ,in, is the wavelet coefficient; the differential criterion value is expressed as:

[0018] ;

[0019] in, and is the dynamic coefficient.

[0020] According to some embodiments of the present invention, identifying a fault based on the differential criterion value and processing the fault includes:

[0021] When the differential criterion value is less than or equal to 0, it is determined to be normal and without fault;

[0022] When the differential criterion value is greater than 0, it is determined that a fault exists, and the fault type is identified and the fault is processed.

[0023] According to some embodiments of the present invention, identifying the fault type and handling the fault includes:

[0024] 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 a high-resistance ground fault;

[0025] When the amplitude of the power frequency component is greater than a third preset value, determining that the fault type is a short circuit fault;

[0026] When a fault occurs, a trip command is sent to the corresponding circuit breaker, and full waveform data before and after the fault is recorded.

[0027] According to some embodiments of the present invention, a step of dynamic parameter adjustment is further included, specifically including:

[0028] At preset time intervals, the value of the dynamic coefficient is adjusted based on the latest fault data using the particle swarm optimization algorithm;

[0029] When it is detected that the distributed power penetration rate is greater than the fourth preset value, the value.

[0030] On the other hand, according to an embodiment of the present invention, a multi-terminal differential protection system for a rural distribution network includes a broadband synchronous sampling device, a communication network, and a differential protection master station, wherein the broadband synchronous sampling device is used to collect three-phase current signals from each node of the distribution network, obtain sampling data, record the timestamps corresponding to the sampling data, pre-process the sampling data, align the timestamps of the multi-terminal data, and extract the power frequency component and high-frequency transient component of the pre-processed sampling data; the communication network is used to transmit data between the broadband synchronous sampling device and the differential protection master station; the differential protection master station is used to calculate a differential criterion value based on the power frequency component and the high-frequency transient component, identify faults based on the differential criterion value, and process the faults.

[0031] On the other hand, a controller according to an embodiment of the present invention includes at least one control processor and a memory for communicating with the at least one control processor; the memory stores instructions that can be executed by the at least one control processor, and the instructions are executed by the at least one control processor so that the at least one control processor can execute the above-mentioned rural distribution network multi-terminal differential protection method.

[0032] On the other hand, according to a computer-readable storage medium of an embodiment of the present invention, the computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to enable a computer to execute the above-mentioned rural distribution network multi-terminal differential protection method.

[0033] 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 adopting the power frequency component and the high-frequency transient component as the differential criterion, the sensitivity limitation of traditional power frequency protection to high-resistance faults is broken through, and the detection sensitivity is improved.

[0034] Additional aspects and advantages of the present invention will be set forth in part in the description which follows and, in part, will be obvious from the description which follows, or may be learned by practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] The above and / or additional aspects and advantages of the present invention will become apparent and readily understood from the following description of the embodiments with reference to the accompanying drawings, in which:

[0036] Figure 1 This is a flowchart of the steps of the multi-terminal differential protection method for rural distribution network according to an embodiment of the present invention;

[0037] Figure 2 Schematic diagram of the structure of a multi-terminal differential protection system for a rural distribution network according to an embodiment of the present invention. DETAILED DESCRIPTION

[0038] The embodiments of the present invention are described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present application and are not to be construed as limiting the present application. The step numbers in the following embodiments are provided only for the convenience of explanation and do not limit the order of the steps. The order of execution of the steps in the embodiments can be adaptively adjusted according to the understanding of those skilled in the art.

[0039] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, they cannot be understood as limitations on the present invention.

[0040] The terms "first," "second," "third," and "fourth," etc., in the specification, claims, and accompanying drawings of the present invention are used to distinguish between different items, not to describe a specific order. Furthermore, the terms "including," "having," and any variations thereof, are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or elements is not limited to the listed steps or elements, but may optionally include steps or elements not listed, or may optionally include other steps or elements inherent to the process, method, product, or apparatus.

[0041] References to "embodiments" in this disclosure mean that a particular feature, structure, or characteristic described in connection with the embodiment may be included in at least one embodiment of the disclosure. The appearance of this phrase in various places in the specification does not necessarily refer to the same embodiment, nor does it constitute an independent or alternative embodiment that is mutually exclusive of other embodiments. It is understood, both explicitly and implicitly, by those skilled in the art that the embodiments described herein may be combined with other embodiments.

[0042] Currently, the differential protection method for rural distribution networks has the following disadvantages:

[0043] (1) Rural distribution networks have long lines and many branches. Traditional current differential protection is easily affected by the harmonic injection of distributed power sources and the weak characteristics of high-resistance grounding faults, resulting in insufficient sensitivity.

[0044] (2) Existing synchronous sampling technologies are mostly designed for industrial frequency, and the accuracy of broadband transient signal acquisition is insufficient. In addition, the multi-terminal clock synchronization accuracy is difficult to meet the μs level requirements.

[0045] (3) In a hybrid communication environment, inconsistent data transmission delays lead to errors in differential criterion calculations.

[0046] 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 adopting the power frequency component and the high-frequency transient component as the differential criterion, it breaks through the sensitivity limitation of traditional power frequency protection to high-resistance faults; through the hybrid synchronization mechanism of satellite timing + PTP, it achieves μs-level synchronization accuracy for long rural lines.

[0047] The following describes in detail the rural distribution network multi-terminal differential protection method, system, controller and medium according to the embodiments of the present invention with reference to the accompanying drawings.

[0048] On the one hand, the embodiment of the present invention proposes a multi-terminal differential protection method for rural distribution network, such as Figure 1 As shown, the method includes but is not limited to steps S100 to S500.

[0049] Step S100: collecting three-phase current signals of each node in the distribution network through the broadband synchronous sampling device 100 to obtain sampling data, and recording the timestamp corresponding to the sampling data;

[0050] Specifically, in this example, a broadband synchronous sampling device 100 is deployed at each node of the distribution network to collect current signals in the 0.1-2 kHz frequency band (or other frequency bands), and time synchronization of each node is achieved through GPS / Beidou dual-mode timing and IEEE 1588 PTP protocol, with a synchronization error of ≤1μs.

[0051] Step S200: pre-processing the sampled data and aligning the timestamps of the multi-terminal data;

[0052] Specifically, the broadband synchronous sampling device 100 uses an adaptive filter to suppress noise (such as clutter other than 50Hz power frequency interference); at the same time, it performs Z-score normalization on the current amplitude to eliminate dimensional differences; and aligns multi-terminal data timestamps based on the PTP protocol.

[0053] Step S300: extracting the power frequency component and high-frequency transient component of the pre-processed sampled data;

[0054] Specifically, the broadband synchronous sampling device 100 adopts a parallel filtering architecture based on FPGA to separate the power frequency and high-frequency signals, thereby extracting the power frequency component and the high-frequency transient component.

[0055] Step S400: Calculating a differential criterion value based on the power frequency component and the high-frequency transient component;

[0056] Specifically, by combining the power frequency component and the high-frequency transient component as the differential criterion, the limitation of the sensitivity of traditional power frequency protection to high-resistance faults is broken through.

[0057] Step S500: Identify the fault according to the differential criterion value and handle the fault.

[0058] According to the multi-terminal differential protection method for rural distribution networks in an embodiment of the present invention, by adopting the power frequency component and the high-frequency transient component as the differential judgment criterion, it breaks through the sensitivity limitation of traditional power frequency protection to high-resistance faults and improves the detection sensitivity; through the hybrid synchronization mechanism of satellite timing + PTP, it achieves μs-level synchronization accuracy for long rural lines.

[0059] In the embodiment of the present application, the above-mentioned rural distribution network multi-terminal differential protection method is applied to the rural distribution network multi-terminal differential protection system, such as Figure 2 As 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 achieve real-time data collection, transmission, and decision-making for multi-terminal differential protection in rural distribution networks.

[0060] Edge side: Deploy a broadband synchronous sampling device 100 to complete data collection and preprocessing.

[0061] Communication layer: Deploy a hybrid communication network 200 of optical fiber and 5G to ensure low-latency and highly reliable transmission.

[0062] Master station side: centralized processing platform, executing multi-terminal data fusion and protection logic.

[0063] In this example, the broadband synchronous sampling device 100 includes a current sensor, a satellite timing module, and a data preprocessing unit. The current sensor can include a Rogowski coil (fundamental wave 0.1-1kHz, accuracy ±0.2%), a high-frequency Hall probe (transient 1-2kHz, sampling rate 10kHz), etc., and is equipped with a 16-bit ADC module that supports synchronous sampling (simultaneous sampling of three-phase current). The satellite timing module uses a GPS / Beidou dual-mode receiver (1PPS pulse, time error ≤100ns) and adopts the IEEE 1588 PTP protocol stack (hardware timestamp recording). The data preprocessing unit has the following functions:

[0064] Anti-aliasing filter (cut-off frequency 2.5kHz);

[0065] Power frequency component isolation (band-stop filtering 50Hz±5Hz);

[0066] Synchronous sampling:

[0067] Align the sampling clocks of each node based on the PTP protocol (μs-level synchronization).

[0068] Outputs a timestamped data stream.

[0069] Furthermore, in some embodiments of the present application, the above-mentioned step S300: extracting the power frequency component and the high-frequency transient component of the pre-processed sampled data includes the following two steps:

[0070] Step S310: extracting the amplitude and phase of the power frequency component by fast Fourier transform to generate a fundamental current vector;

[0071] Step S320: using Daubechies 4 wavelet packet decomposition to extract the high-frequency transient component of the preset sub-band.

[0072] Specifically, the data pre-processing unit adopts an FPGA-based parallel filtering architecture to separate the power frequency and high-frequency signals, thereby extracting the power frequency component and the high-frequency transient component. Fundamental wave extraction: The amplitude of the power frequency component is calculated by fast Fourier transform (FFT). ) and phase (θ). High frequency decomposition: Daubechies 4 wavelet packet decomposition (2-10kHz subband energy ). According to the amplitude and phase of the power frequency component, the fundamental current vector can be generated: ; The high-frequency transient component can be expressed as ,in, The data output by the broadband synchronous sampling device 100 to the differential protection master station is a compressed data packet. Compression mode: The compression mode (lossy / hybrid / lossless) is switched based on the BB and RR. Fundamental wave compression: An improved LZW algorithm (complex number splitting compression, compression ratio ≥ 60%) is used. High-frequency compression: Wavelet coefficient threshold truncation (retaining the first 30% energy subband). Timestamp compression: Golomb coding (Δt difference sequence) is used. The format of the compressed data packet output by the broadband synchronous sampling device 100 is: [compression mode | fundamental wave data | high-frequency coefficients | encoded timestamp]. Communication protocol: MQTT or IEC101 (QoS = 1, ensuring at least once delivery).

[0073] Furthermore, in some embodiments of the present application, the communication network includes a fiber channel and a 5G channel. The fiber channel is used to transmit a reference clock signal, and the 5G channel is used to transmit sampled data. Specifically, the fiber channel has the following functions: transmitting PTP synchronization messages (Sync / Follow_Up / Delay_Resp); and transmitting configuration instructions issued by the differential protection master station to the broadband synchronous sampling device 100. The fiber channel's performance indicators are: one-way delay ≤ 1ms, jitter ≤ 10μs, support for ring topology, and redundant path switchover time < 50ms. The 5G channel has the following functions: transmitting compressed feature data packets from the broadband synchronous sampling device 100 to the differential protection master station and performing heartbeat detection between the broadband synchronous sampling device 100 and the differential protection master station at each edge node. Optimized design: 1. Slicing technology: Allocating dedicated network slices for differential protection (guaranteed bandwidth ≥ 1Mbps). 2. Dynamic bandwidth adaptation: Adjusting the compression mode based on the bandwidth (e.g., enabling lossy compression when bandwidth < 1Mbps). When communication between an edge node and the master is interrupted, the edge node activates its local cache (storing the last 10 seconds of data). After the master detects a timeout, it switches to a neighboring node to reconstruct the faulty area. If data verification fails, the master sends a NACK command, prompting the edge node to retransmit and temporarily increase the compression level (e.g., hybrid to lossless).

[0074] After receiving the compressed data packet from the broadband synchronous sampling device, the differential protection master station first reconstructs the data. This includes LZW decompression of the fundamental wave, reconstruction of the high-frequency component through inverse wavelet transform, decoding the Δt sequence, and accumulating and recovering the absolute time to align the timestamps. After data reconstruction, the differential criterion value is calculated based on the power frequency component and the high-frequency transient component. The specific calculation method is as follows:

[0075] ;

[0076] in, and is a dynamic coefficient, which is adjusted dynamically according to the actual network topology. In this example, =1.2, =0.8. It should be noted that and It can also be set to other values ​​according to actual conditions.

[0077] Furthermore, in some embodiments of the present application, the above-mentioned step S500: identifying a fault according to a differential criterion value and processing the fault includes the following two steps:

[0078] Step S510: When the differential criterion value is less than or equal to 0, it is determined to be normal and without fault;

[0079] Step S520: When the differential criterion value is greater than 0, it is determined that a fault exists, and the fault type is identified and the fault is processed.

[0080] 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 collection step is returned. When a fault exists, the fault type is identified and the fault is handled. Specifically, step S520 includes the following three steps:

[0081] Step S521: 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 a high-resistance ground fault;

[0082] Step S522: when the amplitude of the power frequency component is greater than a third preset value, determining that the fault type is a short circuit fault;

[0083] Step S523: When a fault occurs, a trip command is sent to the corresponding circuit breaker, and full waveform data before and after the fault is recorded.

[0084] Specifically, in this example, the first preset value is , the second preset value is , the third preset value is ,in, Indicates the rated fundamental current, Represents the maximum value of high-frequency transient current; then when and When , the fault type is high resistance ground fault; when When a short circuit occurs, a trip command is sent to the corresponding circuit breaker (operation time ≤ 30ms), and full waveform data 1s before and after the fault is recorded for subsequent analysis.

[0085] Furthermore, in some embodiments of the present application, the rural distribution network multi-terminal differential protection method further includes a step of dynamic parameter adjustment, specifically including:

[0086] At preset time intervals, the value of the dynamic coefficient is adjusted based on the latest fault data using the particle swarm optimization algorithm;

[0087] When it is detected that the distributed power penetration rate is greater than the fourth preset value, the value.

[0088] Specifically, in this example, every 24 hours (or other time period), the system will fine-tune the system based on the latest fault data. and The value of is fine-tuned by incremental particle swarm optimization algorithm to maximize the fault recognition rate; if the distributed power penetration rate is detected to be greater than 50%, the value of Weight to improve the sensitivity of high-frequency components.

[0089] Furthermore, in some embodiments of the present application, when the communication link of a node in the distribution network is interrupted, the differential criterion is reconstructed based on the remaining node data, and a directional element is introduced to locate the fault interval.

[0090] Furthermore, in this application, time synchronization is performed based on the satellite timing module and the PTP protocol, including the following processes:

[0091] 1. Master and slave clock initialization

[0092] 1.1 Master clock configuration (master node):

[0093] Connect to the GPS / Beidou dual-mode timing source to generate 1PPS (pulse per second) and ToD (time message).

[0094] Start the PTP protocol stack and set it to Grandmaster mode, which has the highest priority.

[0095] 1.2 Slave clock configuration (slave node):

[0096] Initialize the local crystal oscillator, set it to Slave mode, and listen to the Announce message from the master clock.

[0097] Enable the hardware timestamp module (FPGA / PHY chip), with an accuracy of ≤100ns.

[0098] 2. Synchronous message interaction process

[0099] Sequential steps (in chronological order):

[0100]

[0101] 3. Delay and offset calculation

[0102] One-way transmission delay calculation:

[0103] ;

[0104] Assuming that the bidirectional paths in the network are symmetrical, the impact of clock frequency deviation is eliminated.

[0105] Slave clock deskew:

[0106] ;

[0107] Adjust local time from the clock:

[0108] .

[0109] 4. Hybrid Network Asymmetric Compensation

[0110] Scenario: A mixed path of optical fiber (fixed delay) and 5G (dynamic delay) exists between the master and slave clocks.

[0111] 4.1 Fixed delay pre-calibration:

[0112] The fiber segment delay dfiber is measured using an OTDR (e.g., dfiber = 0.5 ms).

[0113] 4.2 Dynamic Delay Measurement:

[0114] 5G links regularly measure RTT (Round-Trip Time):

[0115] ;

[0116] in 、 、 、 Sync / Delay_Req interaction timestamp of the 5G link.

[0117] 5. Exception handling and recovery

[0118] 5.1. Sync message loss detection:

[0119] The slave clock does not receive any message for three consecutive Sync cycles → an alarm is triggered.

[0120] Switch to local timekeeping mode (crystal stability ±1ms / hour).

[0121] 5.2. Master clock switching:

[0122] If the master clock fails, the Best Master Clock Algorithm (BMCA) elects a new master clock (the node with the second highest priority) within 5 seconds.

[0123] 5.3. Large offset processing:

[0124] If the calculated |offset| is greater than 10μs, make corrections gradually (each adjustment is ≤ 1μs) to avoid data disorder caused by time jumps.

[0125] The multi-terminal differential protection method and system for rural distribution networks, according to embodiments of the present invention, overcomes the sensitivity limitations of traditional power-frequency protection for high-resistance faults by employing both power-frequency and high-frequency transient components as differential criteria. A hybrid synchronization mechanism combining satellite timing and PTP achieves μs-level synchronization accuracy for long rural lines. By employing a broadband synchronous sampling device, multi-source clock synchronization compensation, and a composite differential criterion, the system addresses the sensitivity and reliability challenges of rural distribution network protection. The measured fault detection time is ≤25ms, a 40% reduction compared to traditional methods. The accuracy rate for identifying high-resistance ground faults (transition resistance >5000Ω) is ≥95%.

[0126] On the other hand, an embodiment of the present application further provides a controller, including:

[0127] The processor may be implemented 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 in the embodiments of the present application;

[0128] 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). The memory can store an operating system and other application programs. When the technical solutions provided in the embodiments of this specification are implemented through software or firmware, the relevant program code is stored in the memory and is called by the processor to execute the rural distribution network multi-terminal differential protection method of the embodiments of this application;

[0129] Input / output interface, used to realize information input and output;

[0130] Communication interface, used to realize communication interaction between this device and other devices. Communication can be achieved through wired means (such as USB, network cable, etc.) or wireless means (such as mobile network, Wi-Fi, Bluetooth, etc.);

[0131] The bus, which transfers information between the various components of the device (such as the processor, memory, input / output interfaces, and communication interfaces);

[0132] The processor, memory, input / output interface and communication interface are connected to each other through a bus within the device.

[0133] An embodiment of the present application also provides a storage medium, which is a computer-readable storage medium. The storage medium stores a computer program, and when the computer program is executed by a processor, the above-mentioned rural distribution network multi-terminal differential protection method is implemented.

[0134] The memory, as a non-transient computer-readable storage medium, can be used to store non-transient software programs and non-transient computer executable programs. In addition, the memory may include a high-speed random access memory, and may also include a non-transient memory, such as at least one disk storage device, a flash memory device, or other non-transient solid-state storage device. In some embodiments, the memory optionally includes a memory remotely located relative to the processor, and these remote memories can be connected to the processor via a network. Examples of the above-mentioned networks include but are not limited to the Internet, an intranet, a local area network, a mobile communication network and a combination thereof. The device embodiments described above are merely schematic, wherein the units described as separate components may or may not be physically separated, and are located in one place, or may be distributed to multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the present embodiment.

[0135] Although specific embodiments are described herein, those skilled in the art will recognize that many other modifications or alternative embodiments are also within the scope of this disclosure. For example, any of the functions and / or processing capabilities described in conjunction with a particular device or component may be performed by any other device or component. In addition, although various exemplary implementations and architectures have been described in accordance with embodiments of the present disclosure, those skilled in the art will recognize that many other modifications to the exemplary implementations and architectures described herein are also within the scope of this disclosure.

[0136] Some aspects of the present disclosure have been described above with reference to the block diagrams and flow charts of the systems, methods, systems and / or computer program products according to the exemplary embodiments. It should be understood that the combination of one or more blocks in the block diagram and the flow chart and the blocks in the block diagram and the flow chart can be realized by executing computer executable program instructions respectively. Equally, according to some embodiments, some blocks in the block diagram and the flow chart may not need to be executed in the order shown, or may not need to be executed in full. In addition, additional components and / or operations beyond those components and / or operations shown in the blocks in the block diagram and the flow chart may be present in certain embodiments.

[0137] Therefore, the blocks in the block diagrams and flow charts support combinations of means for performing the specified functions, combinations of elements or steps for performing the specified functions, and program instruction means for performing the specified functions. It should also be understood that each block in the block diagrams and flow charts, and combinations of blocks in the block diagrams and flow charts, can be implemented by a dedicated hardware computer system that performs the specific functions, elements, or steps, or a combination of dedicated hardware and computer instructions.

[0138] 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 functionality described herein (e.g., one or more operations of the illustrative methods described herein) to be performed.

[0139] Software component can be encoded with any one in various programming languages.A kind of exemplary programming language can be low-level programming language, such as the assembly language associated with specific hardware architecture and / or operating system platform.Comprise that the software component of assembly language instruction may need to be converted to executable machine code by assembler before being executed by hardware architecture and / or platform.Another exemplary programming language can be a more advanced programming language, and it can be transplanted across multiple architectures.Comprise that the software component of more advanced programming language may need to be converted to intermediate representation by interpreter or compiler before execution.Other examples of programming language include but are not limited to macro language, shell or command language, job control language, script language, database query or search language or report writing language.In one or more exemplary embodiments, the software component that comprises the instruction of one in the above-mentioned programming language example can be directly executed by operating system or other software component, without first being converted into another form.

[0140] Software components can be stored as files or other data storage structures. Software components of similar types or related functions can be stored together, such as in a specific directory, folder, or library. Software components can be static (e.g., preset or fixed) or dynamic (e.g., created or modified at execution time).

[0141] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the scope of the present invention.

Claims

1. A multi-terminal differential protection method for a rural distribution network, characterized in that: The following steps are involved: The three-phase current signal of each node of the distribution network is collected by a broadband synchronous sampling device to obtain sampling data, and the timestamp corresponding to the sampling data is recorded; Preprocessing the sampled data and aligning timestamps of multi-terminal data; Extracting the power frequency component and high-frequency transient component of the pre-processed sampling data; Calculating a differential criterion value according to the power frequency component and the high-frequency transient component; Identifying a fault according to the differential criterion value and processing the fault; 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 the three-phase current signal of each node. The satellite timing module is used to provide the timestamp corresponding to the sampled data. The data preprocessing unit is used to preprocess the sampled data, remove noise, perform Z-score normalization on the current amplitude, and align the multi-terminal data timestamps 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 sampled data. The extracting of the power frequency component and the high-frequency transient component of the preprocessed sampled data includes: The amplitude and phase of the power frequency component are extracted by fast Fourier transform to generate the fundamental current vector; Daubechies 4 wavelet packet decomposition is used to extract the high-frequency transient components of the preset subband; The fundamental current vector is expressed as: ,in, is the amplitude of the power frequency component, is the phase of the power frequency component; the high-frequency transient component is expressed as ,in, is the wavelet coefficient; the differential criterion value is expressed as: ； in, and is the dynamic coefficient, and n is the total number of high-frequency transient components.

2. The multi-terminal differential protection method for rural distribution network according to claim 1, characterized in that: The identifying a fault according to the differential criterion value and processing the fault includes: When the differential criterion value is less than or equal to 0, it is determined to be normal and without fault; When the differential criterion value is greater than 0, it is determined that a fault exists, and the fault type is identified and the fault is processed.

3. The multi-terminal differential protection method for rural distribution network according to claim 2, characterized in that: The identifying of the fault type and handling of the fault include: 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 a high-resistance ground fault; When the amplitude of the power frequency component is greater than a third preset value, determining that the fault type is a short circuit fault; When a fault occurs, a trip command is sent to the corresponding circuit breaker, and full waveform data before and after the fault is recorded.

4. The multi-terminal differential protection method for rural distribution network according to claim 1, characterized in that: It also includes the steps of dynamic parameter adjustment, including: At preset time intervals, the value of the dynamic coefficient is adjusted based on the latest fault data using the particle swarm optimization algorithm; When it is detected that the distributed power penetration rate is greater than the fourth preset value, the value.

5. A multi-terminal differential protection system for rural distribution networks, characterized in that: The system comprises a broadband synchronous sampling device, a communication network, and a differential protection master station, wherein the broadband synchronous sampling device is used to collect three-phase current signals from each node of the distribution network, obtain sampled data, record the timestamps corresponding to the sampled data, pre-process the sampled data, align the timestamps of multi-terminal data, and extract the power frequency component and high-frequency transient component of the pre-processed sampled data; the communication network is used to transmit data between the broadband synchronous sampling device and the differential protection master station; the differential protection master station is used to calculate a differential criterion value based on the power frequency component and the high-frequency transient component, identify a fault based on the differential criterion value, and process the fault; The step of extracting the power frequency component and high-frequency transient component of the preprocessed sampled data includes: The amplitude and phase of the power frequency component are extracted by fast Fourier transform to generate the fundamental current vector; Daubechies 4 wavelet packet decomposition is used to extract the high-frequency transient components of the preset subband; The fundamental current vector is expressed as: ,in, is the amplitude of the power frequency component, is the phase of the power frequency component; the high-frequency transient component is expressed as ,in, is the wavelet coefficient; the differential criterion value is expressed as: ； in, and is the dynamic coefficient, and n is the total number of high-frequency transient components.

6. A controller, characterized in that: It includes at least one control processor and a memory for communicating with the at least one control processor; the memory stores instructions that can be executed 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 rural distribution network multi-terminal differential protection method as described in any one of claims 1 to 4.

7. A computer-readable storage medium, characterized in that The computer-readable storage medium stores computer-executable instructions, and the computer-executable instructions are used to enable a computer to execute the rural distribution network multi-terminal differential protection method according to any one of claims 1 to 4.

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