Synchronous phasor differential protection method and device for power distribution network, electronic equipment and storage medium

Abstract

The invention discloses a power distribution network synchronous phasor differential protection method and device, electronic equipment and a storage medium, and belongs to the technical field of power distribution network relay protection.The method comprises the steps that according to current parameters of a power distribution network line, the current phase angles of the two ends of the line at each sampling moment are calculated; calculating a current absolute difference angle between the two ends of the line at each sampling moment; calculating a current absolute superposition difference angle between adjacent sampling moments according to the current absolute difference angle corresponding to each sampling moment; the current absolute superposition difference angle is compared with a preset fault threshold value, if the current absolute superposition difference angle is larger than the fault threshold value, it is judged that an internal fault occurs in the current line, and a corresponding tripping signal is sent to the corresponding circuit breaker, so that the corresponding circuit breaker conducts fault isolation on the current line. The problem that in the prior art, a differential protection mode depending on current amplitude information is limited by the Ohm law, and consequently detection fails can be solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power distribution network relay protection, and in particular to a power distribution network synchronous phasor differential protection method and device, an electronic device and a storage medium. BACKGROUND

[0002] Protection systems are an important part of the power grid infrastructure. They ensure that network components are isolated under extreme conditions such as faults, to protect assets, maintain network stability and keep normal parts operational, thus supplying end users. Protection systems play a role in different stages: fault detection, trip generation, trip validation and element isolation. In the first stage, a fault detection or protection scheme is used to detect the occurrence of a fault. In the second stage, a trip circuit is used to generate a trip signal. Thereafter, the trip signal is transmitted to a circuit breaker, and thus the circuit breaker operates in the third stage to isolate the faulty component. If the operation of the circuit breaker is successful and the fault has been cleared, a trip signal validation is transmitted to the control system or protection relay in the fourth stage. The purpose of this stage is to ensure that the protection system is aware of the status of the circuit breaker and takes appropriate measures after a fault, which reduces the risk of equipment damage, improves operational reliability and minimizes downtime. The successful execution of the tasks in each stage means the completion of the fault detection and isolation cycle of network protection, and various types of technology are used for the fault detection task in the power distribution network, with reference to the first stage.

[0003] The most widely recognized protection method for power distribution networks is the overcurrent protection scheme and the current differential scheme. The overcurrent protection scheme is very effective for simple, passive and radial power distribution networks; the current differential scheme is often used to protect ring or partially meshed networks, busbars and transformers, and is also used to protect power distribution lines. However, both methods use current amplitude information to make protection decisions, and relying only on current amplitude information is limited by Ohm's law (current is inversely proportional to resistance), and faults with high ohmic values contribute a negligible amount of differential current during a fault, and the fault current is attenuated to noise levels when the resistance > 100 Ω, resulting in detection failure and reducing the sensitivity of the current differential scheme. SUMMARY

[0004] The present application provides a power distribution network synchronous phasor differential protection method, device, electronic device and storage medium, which can solve the problem that the differential protection method relying on current amplitude information in the prior art is limited by Ohm's law, resulting in detection failure.

[0005] To solve the above technical problems, the present application provides a power distribution network synchronous phasor differential protection method, comprising: obtaining a current parameter of a power distribution network line; wherein the current parameter comprises a three-phase current waveform and a fundamental frequency current vector; According to the current parameter, a current phase angle at each sampling moment is calculated, and according to the current phase angle, an absolute current difference angle between both ends of the line at each sampling moment is calculated, and then according to the absolute current difference angle corresponding to each sampling moment, an absolute superimposed current difference angle between adjacent sampling moments is calculated. The absolute superimposed current difference angle is compared with a preset fault threshold value, if the absolute superimposed current difference angle is greater than the fault threshold value, it is determined that an internal fault occurs in the current line, and a corresponding trip signal is sent to the corresponding circuit breaker to make the corresponding circuit breaker isolate the fault of the current line.

[0006] As a preferred solution, it further comprises: According to the current parameter, a current amplitude variation rate of the current line is calculated. If the absolute superimposed current difference angle is not greater than the fault threshold value, and the current amplitude variation rate of the current line is less than a preset variation rate threshold value, it is determined that no fault occurs in the current line; if the absolute superimposed current difference angle is not greater than the fault threshold value, and the current amplitude variation rate of the current line is not less than the preset variation rate threshold value, it is determined that an external fault occurs in the current line, and a corresponding trip signal is sent to the corresponding circuit breaker to make the corresponding circuit breaker isolate the fault of the current line.

[0007] As a preferred solution, the absolute superimposed current difference angle is calculated according to the following formula: ; ; ; ; Wherein, is the absolute superimposed current difference angle; is the absolute current difference angle; is the absolute current difference angle after the line fault; is the absolute current difference angle before the line fault; is the current phase angle at the M end of the line section; is the current phase angle at the N end of the line section; is the current at the M end of the line section; is the current at the N end of the line section; is the positive sequence current at the M end of the line section; is the positive sequence current at the N end of the line section.

[0008] As a preferred solution, the fault threshold value is: ; Wherein, is the fault threshold value. is the maximum value of the absolute superimposed difference angle corresponding to the external fault EFS and the no-fault NFS working conditions; SF is a safety margin coefficient.

[0009] On the basis of the above-mentioned embodiments, another embodiment of the application provides a power distribution network synchronous phasor differential protection device, comprising: a current parameter acquisition module, a current absolute superimposed difference angle calculation module, and a fault judgment and isolation module. The current parameter acquisition module is configured to acquire current parameters of a power distribution network line, wherein the current parameters comprise three-phase current waveforms and a fundamental frequency current vector. The current absolute superimposed difference angle calculation module is configured to calculate current phase angles at each sampling time according to the current parameters, and calculate current absolute difference angles between two ends of the line at each sampling time according to the current phase angles, and then calculate current absolute superimposed difference angles between adjacent sampling times according to the current absolute difference angles corresponding to each sampling time. The fault judgment and isolation module is configured to compare the current absolute superimposed difference angle with a preset fault threshold value, and if the current absolute superimposed difference angle is greater than the fault threshold value, it is determined that an internal fault occurs in the current line, and a corresponding trip signal is sent to the corresponding circuit breaker to isolate the fault of the current line.

[0010] As a preferred scheme, it further comprises: calculating a current amplitude variation rate of the current line according to the current parameters; If the current absolute superimposed difference angle is not greater than the fault threshold value, and the current amplitude variation rate of the current line is less than a preset variation rate threshold value, it is determined that no fault occurs in the current line; if the current absolute superimposed difference angle is not greater than the fault threshold value, and the current amplitude variation rate of the current line is not less than the preset variation rate threshold value, it is determined that an external fault occurs in the current line, and a corresponding trip signal is sent to the corresponding circuit breaker to isolate the fault of the current line.

[0011] As a preferred scheme, the current absolute superimposed difference angle is calculated according to the following formula: ; ; ; ; wherein, is the current absolute superimposed difference angle; is the current absolute difference angle; is the current absolute difference angle after the line fault; is the absolute difference angle of the current of the line before the line fault occurs; is the phase angle of the current at the end of the line section M; is the phase angle of the current at the end of the line section N; is the current at the end of the line section M; is the current at the end of the line section N; is the positive sequence current at the end of the line section M; is the positive sequence current at the end of the line section N.

[0012] As a preferred solution, the fault threshold is: ; wherein, is the fault threshold; is the maximum value of the absolute superimposed difference angle corresponding to the external fault EFS and the non-fault NFS working conditions; SF is a safety margin coefficient.

[0013] On the basis of the above-mentioned embodiments, a further embodiment of the application provides an electronic device, which comprises a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, and the processor implements the power distribution network synchronous phasor differential protection method described in the above-mentioned embodiments of the application when executing the computer program.

[0014] On the basis of the above-mentioned embodiments, a further embodiment of the application provides a storage medium, which comprises a stored computer program, wherein the device where the storage medium is located executes the power distribution network synchronous phasor differential protection method described in the above-mentioned embodiments of the application when the computer program runs.

[0015] Compared with the prior art, the embodiments of the application have the following beneficial effects: The application provides a power distribution network synchronous phasor differential protection method, which acquires current parameters of a power distribution network line; wherein the current parameters comprise three-phase current waveforms and a fundamental frequency current vector; according to the current parameters, the phase angles of the currents at both ends of the line at each sampling time are calculated, and according to the phase angles of the currents, the absolute difference angles of the currents between both ends of the line at each sampling time are calculated, and then the absolute superimposed difference angles of the currents between adjacent sampling times are calculated according to the absolute difference angles of the currents corresponding to each sampling time; the absolute superimposed difference angle of the current is compared with a preset fault threshold, if the absolute superimposed difference angle of the current is greater than the fault threshold, it is determined that an internal fault occurs in the current line, and a corresponding trip signal is sent to a corresponding circuit breaker, so that the corresponding circuit breaker isolates the fault of the current line.

[0016] Compared to existing technologies that use current amplitude information as the detection object, this invention shifts the detection object from the amplitude domain to the phase domain, using the current phase angle as the detection object. It calculates the absolute superposition differential angle of the current between adjacent sampling times using the current phase angles at both ends of the line. By utilizing the current phase abrupt change that still exists under high-impedance faults as a criterion, it physically avoids the attenuation limitation problem inherent in relying solely on current amplitude, preventing detection failures and improving the sensitivity of the current differential scheme. Attached Figure Description

[0017] Figure 1 This is a schematic flowchart of a method for synchronous phasor differential protection of a distribution network provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the line before the fault occurred on line segment MN; Figure 3 This is a schematic diagram of the line when an internal fault occurs in line segment MN; Figure 4 This is a schematic diagram of the line when an external fault occurs in line segment MN; Figure 5 This is a schematic diagram of the structure of a synchronous phasor differential protection device for a power distribution network provided in an embodiment of the present invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions of this application will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0019] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the application; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the drawings are intended to cover non-exclusive inclusion.

[0020] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0021] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0023] In the description of the embodiments of this application, the terms "multiple" and "several" refer to two or more (including two), similarly, "multiple groups" refer to two or more (including two groups), and "multiple pieces" refer to two or more (including two pieces).

[0024] In the description of the embodiments of this application, unless otherwise expressly specified and limited, technical terms such as "installation," "connection," "joining," and "fixing" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. For those skilled in the art, the specific meaning of the above terms in the embodiments of this application can be understood according to the specific circumstances.

[0025] Example 1 Please refer to Figure 1 To address the problem that existing differential protection methods relying on current amplitude information are limited by Ohm's law, leading to detection failure, this invention provides a flowchart of a distribution network synchronous phasor differential protection method. This invention shifts the detection target from the amplitude domain to the phase domain, utilizing the positive-sequence current phase abrupt change that still exists under high-resistance faults. As a criterion, this approach physically avoids the attenuation limitation that exists when relying solely on amplitude, while also incorporating current amplitude information as an auxiliary criterion. The specific steps include: S1. Obtain the current parameters of the distribution network lines; wherein, the current parameters include: three-phase current waveforms and fundamental frequency current vector; Specifically, when performing differential protection, this invention first acquires and synchronizes data in the following way, ultimately obtaining the current parameters (three-phase current waveforms and fundamental frequency current vector) of the distribution network line: A P-level D-PMU is deployed at both ends of the distribution network line to sample current signals at a high rate of ≥50 Hz and generate synchronization phasors using the IEEE C37.118.1a standard. The PMU is a high-precision device used for power system monitoring. Its main function is to measure parameters such as phase angle, amplitude, and frequency of the power grid in real time and transmit these data to the monitoring center via a communication network, providing crucial support for the stable operation of the power system. The PMU software obtains the required current parameters through built-in program algorithms. Software D-PMUs are generally used for simulation analysis of phasor measurements, with the high-rate sampled current signal input to the software D-PMU. These PMUs use the system clock as a synchronization reference to provide timestamps.

[0026] Transformation order components: D-PMU generates phasors in the ABC domain ( , , These phasors are internally transformed into order fields (zero order). Ascending order Negative order ): (1) in, That is, node voltage or line current, and It is a complex number transformation operator.

[0027] The method used by the software D-PMU to generate phasors is based on the C37.118.1a standard, which has been well-proven in PMUs used in transmission utilities. Class P synchronous phasor measurements are superior to Class M synchronous phasor measurements in obtaining the fundamental frequency component of the protection application current, conforming to IEEE C37.118.1a. Therefore, at the monitoring location, analog waveforms are sampled at a fixed rate, treating the fundamental frequency of the power network as 50 Hz.

[0028] Data synchronization mechanism: Use GPS or system clock to add timestamps to phasors to ensure data time alignment at both ends. Exchange phasor data (such as positive sequence components of voltage and current) through GPON fiber optic network and use broadcast messages to achieve multi-terminal sampling synchronization, reducing costs.

[0029] S2. Based on the current parameters, calculate the current phase angle at both ends of the line at each sampling time, and based on the current phase angle, calculate the absolute current difference angle between the two ends of the line at each sampling time. Then, based on the absolute current difference angle corresponding to each sampling time, calculate the absolute current superposition difference angle between adjacent sampling times. Preferably, the absolute superposition differential angle of the currents is calculated according to the following formula: ; ; ; ; in, The differential angle is the absolute superposition of currents; This is the absolute difference angle of the current; This is the absolute differential angle of the current after a line fault occurs. The absolute differential angle of the current before the line fault occurs; The phase angle of the current at end M of line segment; The current phase angle at the N-terminus of the line segment; This represents the current at end M of the line segment; This represents the current at terminal N of the line segment; This represents the positive sequence current at terminal M of line segment M; This represents the positive sequence current at the N-terminal of the line segment.

[0030] Specifically, after acquiring the current parameters of the line, fault characteristics (absolute superposition differential angle of current) are calculated based on the acquired current parameters: The protection scheme proposed in this invention is based on the calculation of the relative change in the differential phase angle of the current. This relative change is obtained using the mature superposition component theory, where the superposition component is defined as the difference between the fundamental frequency after the fault and before the fault. Its mathematical expression can be represented as: (2) in , Before the fault occurred, This indicates a malfunction. and These represent the electrical quantities that need to be analyzed after the fault (a transient value used to represent the sudden change after the fault) and the electrical quantities that need to be analyzed before the fault (a steady-state value before the fault, serving as a reference quantity), respectively. Y represents the absolute differential angle, and C represents the set of complex numbers.

[0031] This invention focuses on exploring and analyzing the direct application of superposition component theory to the current phase difference angle. Specifically, the phase difference angle is calculated using the positive-sequence component phase angles of the currents at both ends of the line, thereby determining the superposition angle. Please refer to... Figure 2 This is a schematic diagram of the line segment MN before the fault occurred. To construct a protection strategy, the following considerations are made. Figure 2 The MN line segment shown is assumed to be monitored at both ends by D-PMUs. The positive sequence current at terminal M of this line segment... It can be represented as: (3) Subsequently, assuming the power flow direction is from node M to node N, the positive sequence current from terminal N is... Based on current Approximately written as: (4) Therefore, the absolute difference angle of the current between the two ends of the line is calculated and expressed as: (5) Therefore, using (2), the absolute superposition difference angle is written as: (6) (1) Before the fault or under normal conditions: Under the conditions prior to the failure, It can be written as: (7) The above formula shows that the absolute phase difference angle of the current at both ends of the line before a fault is approximately 180°. This relationship remains true under normal operating conditions, therefore the absolute phase difference angle before a fault is known. and the absolute phase difference angle after the fault They are almost equal, which makes the angular superposition amount Close to 0.

[0032] (2) Under internal fault conditions: When a fault occurs on the line, the fault point is equivalent to a virtual node, which will cause the two currents at the two ends to be unequal, and consequently, their phase angles will be different. Please refer to... Figure 3 Here is a schematic diagram of the line segment MN when an internal fault occurs. Under the condition of an internal fault, the absolute difference angle of the current between the two ends of the line is written as: (8) Among them, phase angle This is due to the phase angle change caused by the fault branch. Therefore, using (6), the absolute superposition differential angle ASDA of the internal fault is expressed as: It can be calculated by subtracting (7) from (8): (9) (3) Under external fault conditions: Please refer to Figure 4 This is a schematic diagram of the line when an external fault occurs in line segment MN. Figure 4 The diagram illustrates an external fault scenario, where line segment MN is the protected area and line segment NP is the external region of line MN. During the external fault condition, the phase difference angle between the currents at both ends of the monitored line remains approximately equal to... This is because the faulty branch does not affect the phase angle of the monitored line. Therefore, the ASDA during an external fault is expressed as follows: It will equal zero again.

[0033] S3. Compare the absolute superposition differential angle of the current with a preset fault threshold. If the absolute superposition differential angle of the current is greater than the fault threshold, it is determined that a fault has occurred in the current line, and a corresponding trip signal is sent to the corresponding circuit breaker so that the corresponding circuit breaker can isolate the fault in the current line.

[0034] Preferably, the method further includes: calculating the rate of change of the current amplitude of the current line based on the current parameters; if the absolute superposition differential angle of the current is not greater than the fault threshold and the rate of change of the current amplitude of the current line is less than a preset rate of change threshold, then it is determined that there is no fault in the current line; if the absolute superposition differential angle of the current is not greater than the fault threshold and the rate of change of the current amplitude of the current line is not less than a preset rate of change threshold, then it is determined that there is an external fault in the current line, and a corresponding trip signal is sent to the corresponding circuit breaker so that the corresponding circuit breaker can isolate the fault in the current line.

[0035] Preferably, the fault threshold is: ; in, This is the fault threshold; SF is the maximum value of the absolute superposition differential angle corresponding to the out-of-zone fault EFS and fault-free NFS conditions; SF is the safety margin coefficient.

[0036] Specifically, after calculating the absolute superposition difference angle of the current between adjacent sampling times, further fault detection is performed based on the obtained absolute superposition difference angle of the current: From the above, it can be concluded that under internal fault conditions, the absolute superposition differential angle (ASDA) is significantly higher than zero. In external fault (EFS) and no-fault (NFS) scenarios, ASDA is approximately equal to zero. Therefore, the criterion is: Primary criterion: If ASDA > preset fault threshold, it is determined to be an intra-zone fault.

[0037] If ASDA≈0 (i.e., not greater than the preset fault threshold) and the current amplitude monitored by the PMU is stable (i.e., the rate of change of the current amplitude of the current line is less than the preset rate of change threshold), it is determined to be a fault-free condition.

[0038] If ASDA≈0 (i.e., not greater than the preset fault threshold) and the current amplitude monitored by the PMU suddenly increases (i.e., the rate of change of the current amplitude of the current line is not less than the preset rate of change threshold), it is determined to be an external fault.

[0039] Auxiliary criterion: Combining the characteristics of differential current and braking current changes: Fault within the zone: Differential current and braking current increase synchronously; External fault: Braking current increases while differential current remains unchanged.

[0040] Among them, differential current pass The calculated braking current is pass Calculated.

[0041] Threshold confirmation: To achieve effective detection of internal faults, the action threshold needs to be scientifically set. Threshold decision-making needs to consider the following factors: (a) The threshold must accurately distinguish between internal faults and normal operation and external fault conditions, ensuring that alarms are triggered only for internal faults. (b) The influence of fault resistance needs to be considered, especially extreme conditions where high-resistance grounding faults significantly reduce fault current. (c) The threshold setting must ensure that the ASDA value remains below the limit during various switching transient processes such as capacitor bank switching, single / multiple load switching, grid operation mode adjustments, and distributed energy grid connection / off-grid operation, preventing maloperation of the protection device. (d) It needs to be compatible with measurement noise and uncertainty, ensuring that it does not negatively interfere with protection accuracy. Factors (a), (b), and (c) are key to ensuring optimal protection performance. Based on the above factors, the optimal threshold can be set using the following formula: (10) In the formula: the first term corresponds to the threshold decision factors (a)(b)(c): taking the maximum value of ASDA under all external fault (EFS) and no-fault (NFS) conditions. The second term is the safety headroom factor (SF), which reserves an extra margin to prevent protection malfunction.

[0042] When determining whether a fault occurs within or outside the current line zone, the differential protection mechanism is activated: upon meeting the criteria, a trip signal is sent to the circuit breaker to isolate the faulty area. Fault information is simultaneously reported to the master station, and the topology model is updated.

[0043] Therefore, this invention provides a method for synchronous phasor differential protection of distribution networks, which can achieve the following beneficial effects: (1) The ability to detect high-resistance faults has been greatly improved. Because the phase change of the positive sequence current ASDA is analyzed, it can withstand high-resistance faults greater than 800Ω. The phase shift of the positive sequence current caused by the fault point is used for measurement, which breaks the limitation of Ohm's law.

[0044] (2) Multi-scenario anti-interference: By performing absolute value processing and positive sequence filtering on the angle, the problem of misjudgment caused by reverse current is compensated and the false operation rate is reduced.

[0045] Example 2 Please refer to Figure 5This is a schematic diagram of the structure of a distribution network synchronous phasor differential protection device according to an embodiment of the present invention. The device includes: a current parameter acquisition module, a current absolute superposition differential angle calculation module, and a fault judgment and isolation module. The current parameter acquisition module is used to acquire the current parameters of the distribution network line; wherein, the current parameters include: three-phase current waveforms and fundamental frequency current vector; The current absolute superposition differential angle calculation module is used to calculate the current phase angle at both ends of the line at each sampling time based on the current parameters, and to calculate the current absolute differential angle between the two ends of the line at each sampling time based on the current phase angle. Then, based on the current absolute differential angle corresponding to each sampling time, it calculates the current absolute superposition differential angle between adjacent sampling times. The fault judgment and isolation module is used to compare the absolute superposition differential angle of the current with a preset fault threshold. If the absolute superposition differential angle of the current is greater than the fault threshold, it is determined that a fault has occurred in the current line and a corresponding trip signal is sent to the corresponding circuit breaker so that the corresponding circuit breaker can isolate the fault in the current line.

[0046] Preferred options also include: Calculate the rate of change of the current amplitude of the current in the current line based on the current parameters; If the absolute superposition differential angle of the current is not greater than the fault threshold, and the rate of change of the current amplitude of the current line is less than the preset rate of change threshold, then it is determined that there is no fault in the current line; if the absolute superposition differential angle of the current is not greater than the fault threshold, and the rate of change of the current amplitude of the current line is not less than the preset rate of change threshold, then it is determined that there is an external fault in the current line, and a corresponding trip signal is sent to the corresponding circuit breaker so that the corresponding circuit breaker can isolate the fault in the current line.

[0047] Preferably, the absolute superposition differential angle of the currents is calculated according to the following formula: ; ; ; ; in, The differential angle is the absolute superposition of currents; This is the absolute difference angle of the current; This is the absolute differential angle of the current after a line fault occurs. The absolute differential angle of the current before the line fault occurs; The phase angle of the current at end M of line segment; The current phase angle at the N-terminus of the line segment; This represents the current at end M of the line segment; This represents the current at terminal N of the line segment; This represents the positive sequence current at terminal M of line segment M; This represents the positive sequence current at the N-terminal of the line segment.

[0048] Preferably, the fault threshold is: ; in, This is the fault threshold; SF is the maximum value of the absolute superposition differential angle corresponding to the out-of-zone fault EFS and fault-free NFS conditions; SF is the safety margin coefficient.

[0049] It should be noted that the device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separate, and the components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs. Furthermore, in the accompanying drawings of the device embodiments provided by this invention, the connection relationships between modules indicate that they have communication connections, which can be specifically implemented as one or more communication buses or signal lines. Those skilled in the art can understand and implement this without any creative effort.

[0050] Those skilled in the art will clearly understand that, for convenience and brevity, the specific working process of the device described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0051] Example 3 Accordingly, embodiments of the present invention provide an electronic device, the device including a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor executes the computer program to implement the distribution network synchronous phasor differential protection method described in the above embodiments of the invention.

[0052] The electronic device may be a desktop computer, laptop, handheld computer, or cloud server, etc. The device may include, but is not limited to, a processor and a memory.

[0053] The processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), field-programmable gate arrays (FPGAs), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor can be a microprocessor or any conventional processor. The processor is the control center of the device, connecting various parts of the device via various interfaces and lines.

[0054] Example 4 Accordingly, embodiments of the present invention provide a storage medium, the storage medium including a stored computer program, wherein, when the computer program is running, it controls the device where the storage medium is located to execute the distribution network synchronous phasor differential protection method described in the above embodiments of the invention.

[0055] The memory can be used to store the computer program. The processor implements various functions of the device by running or executing the computer program stored in the memory and calling data stored in the memory. The memory may mainly include a program storage area and a data storage area. The program storage area may store the operating system, applications required for at least one function, etc.; the data storage area may store data created based on the use of the mobile phone, etc. In addition, the memory may include high-speed random access memory, and may also include non-volatile memory, such as hard disk, RAM, plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, at least one disk storage device, flash memory device, or other volatile solid-state storage device.

[0056] The storage medium is a computer-readable storage medium, and the computer program is stored in the computer-readable storage medium. When executed by a processor, the computer program can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable medium can include: any entity or device capable of carrying the computer program code, recording media, USB flash drive, portable hard drive, magnetic disk, optical disk, computer memory, read-only memory (ROM), random access memory (RAM), electrical carrier signals, telecommunication signals, and software distribution media, etc. It should be noted that the content included in the computer-readable medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable medium does not include electrical carrier signals and telecommunication signals.

[0057] 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 are also considered to be within the scope of protection of the present invention.

Claims

1. A method for synchronous phasor differential protection of a distribution network, characterized in that, include: Obtain the current parameters of the distribution network lines; wherein, the current parameters include: three-phase current waveforms and fundamental frequency current vector; Based on the current parameters, the current phase angle at both ends of the line at each sampling moment is calculated, and based on the current phase angle, the absolute current difference angle between the two ends of the line at each sampling moment is calculated. Then, based on the absolute current difference angle corresponding to each sampling moment, the absolute current superposition difference angle between adjacent sampling moments is calculated. The absolute superposition differential angle of the current is compared with a preset fault threshold. If the absolute superposition differential angle of the current is greater than the fault threshold, it is determined that a fault has occurred in the current line, and a corresponding trip signal is sent to the corresponding circuit breaker so that the corresponding circuit breaker can isolate the fault in the current line.

2. The method for synchronous phasor differential protection of distribution networks as described in claim 1, characterized in that, Also includes: Calculate the rate of change of the current amplitude of the current in the current line based on the current parameters; If the absolute superposition differential angle of the current is not greater than the fault threshold, and the rate of change of the current amplitude of the current line is less than the preset rate of change threshold, then it is determined that there is no fault in the current line; if the absolute superposition differential angle of the current is not greater than the fault threshold, and the rate of change of the current amplitude of the current line is not less than the preset rate of change threshold, then it is determined that there is an external fault in the current line, and a corresponding trip signal is sent to the corresponding circuit breaker so that the corresponding circuit breaker can isolate the fault in the current line.

3. The method for synchronous phasor differential protection of distribution networks as described in claim 1, characterized in that, The absolute superposition differential angle of the currents is calculated using the following formula: ； ； ； ； in, The differential angle is the absolute superposition of currents; This is the absolute difference angle of the current; This is the absolute differential angle of the current after a line fault occurs. The absolute differential angle of the current before the line fault occurs; The phase angle of the current at end M of line segment; The current phase angle at the N-terminus of the line segment; This represents the current at end M of the line segment; This represents the current at terminal N of the line segment; This represents the positive sequence current at terminal M of line segment M; This represents the positive sequence current at the N-terminal of the line segment.

4. The method for synchronous phasor differential protection of distribution networks as described in claim 1, characterized in that, The fault threshold is: ； in, This is the fault threshold; SF is the maximum value of the absolute superposition differential angle corresponding to the out-of-zone fault EFS and fault-free NFS conditions; SF is the safety margin coefficient.

5. A synchronous phasor differential protection device for power distribution networks, characterized in that, include: The module includes a current parameter acquisition module, a current absolute superposition differential angle calculation module, and a fault judgment and isolation module. The current parameter acquisition module is used to acquire the current parameters of the distribution network line; wherein, the current parameters include: three-phase current waveforms and fundamental frequency current vector; The current absolute superposition differential angle calculation module is used to calculate the current phase angle at both ends of the line at each sampling time based on the current parameters, and to calculate the current absolute differential angle between the two ends of the line at each sampling time based on the current phase angle. Then, based on the current absolute differential angle corresponding to each sampling time, it calculates the current absolute superposition differential angle between adjacent sampling times. The fault judgment and isolation module is used to compare the absolute superposition differential angle of the current with a preset fault threshold. If the absolute superposition differential angle of the current is greater than the fault threshold, it is determined that a fault has occurred in the current line and a corresponding trip signal is sent to the corresponding circuit breaker so that the corresponding circuit breaker can isolate the fault in the current line.

6. The distribution network synchronous phasor differential protection device as described in claim 5, characterized in that, Also includes: Calculate the rate of change of the current amplitude of the current in the current line based on the current parameters; If the absolute superposition differential angle of the current is not greater than the fault threshold, and the rate of change of the current amplitude of the current line is less than the preset rate of change threshold, then it is determined that there is no fault in the current line; if the absolute superposition differential angle of the current is not greater than the fault threshold, and the rate of change of the current amplitude of the current line is not less than the preset rate of change threshold, then it is determined that there is an external fault in the current line, and a corresponding trip signal is sent to the corresponding circuit breaker so that the corresponding circuit breaker can isolate the fault in the current line.

7. The distribution network synchronous phasor differential protection device as described in claim 5, characterized in that, The absolute superposition differential angle of the currents is calculated using the following formula: ； ； ； ； in, The differential angle is the absolute superposition of currents; This is the absolute difference angle of the current; This is the absolute differential angle of the current after a line fault occurs. The absolute differential angle of the current before the line fault occurs; The phase angle of the current at end M of line segment; The current phase angle at the N-terminus of the line segment; This represents the current at end M of the line segment; This represents the current at terminal N of the line segment; This represents the positive sequence current at terminal M of line segment M; This represents the positive sequence current at the N-terminal of the line segment.

8. The distribution network synchronous phasor differential protection device as described in claim 5, characterized in that, The fault threshold is: ； in, This is the fault threshold; SF is the maximum value of the absolute superposition differential angle corresponding to the out-of-zone fault EFS and fault-free NFS conditions; SF is the safety margin coefficient.

9. An electronic device, characterized in that, It includes a processor, a memory, and a computer program stored in the memory and configured to be executed by the processor, wherein the processor, when executing the computer program, implements the distribution network synchronous phasor differential protection method as described in any one of claims 1 to 4.

10. A storage medium, characterized in that, The storage medium includes a stored computer program, wherein, when the computer program is executed, it controls the device where the storage medium is located to perform the distribution network synchronous phasor differential protection method as described in any one of claims 1 to 4.

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