Distribution line overcurrent protection method, electronic equipment and computer storage medium

Abstract

The invention relates to the technical field of power system relay protection, in particular to a distribution line overcurrent protection method, electronic equipment and a computer storage medium. The method includes obtaining a plurality of line voltages and a plurality of line currents. Variable impedance is determined according to the preset unit impedance value, and the variable impedance amplitude is in positive correlation with the preset unit impedance value and the line length of the distribution line. According to the variable impedance, the first line current and the first line voltage, the working voltage is determined, and the first line current is any line current larger than or equal to a preset overcurrent threshold value in the multiple line currents. And determining a phase comparison angle according to the working voltage and the polarization voltage. If the phase comparison angle is within the preset angle range, target action delay is determined, and the target action delay is in negative correlation with the variable impedance amplitude. According to the method and the device, the action time delay corresponding to the line protection device can be determined, so that the action time delay corresponding to each line protection device can be reliably distinguished, and the number of the line protection devices in stepped matching is increased.

Description

Technical Field

[0001] The present application relates to the technical field of relay protection for power systems, and in particular to a distribution line overcurrent protection method, electronic equipment and computer storage medium. Background Art

[0002] In the power system, step coordination is a strategy for overcurrent protection of distribution network lines (hereinafter referred to as distribution lines). The action delay step coordination is an important method of overcurrent protection step coordination. By gradually changing the action delay on each line protection device from the power side to the load side, selective protection of the distribution line is achieved. The more line protection devices are put into step coordination of overcurrent protection, the more accurate the fault point is located, the smaller the isolated fault area is, and the smaller the impact of the fault on the power system is.

[0003] In order to achieve step-by-step coordination, the time difference between the action delays set on each line protection device cannot be less than a certain time difference threshold. However, in order to ensure the rapidity of fault removal, the longest action delay cannot exceed a certain action delay threshold. Therefore, within a certain action delay threshold range, the action delay that can be set in a step-by-step manner is relatively small, and the number of line protection devices that are actually put into step-by-step coordination on the distribution line is relatively small. This results in lower accuracy in fault location and isolation, a larger range of fault isolation, and greater impact on the power system. Summary of the invention

[0004] The present application provides a distribution line overcurrent protection method, device, electronic device and computer-readable storage medium. The action delay corresponding to the line protection device can be determined, so that the action delay corresponding to each line protection device can be reliably distinguished, thereby increasing the number of line protection devices put into step-by-step coordination, so as to reduce the fault range and reduce the impact of line faults on the power system.

[0005] In the first aspect, the present application provides a distribution line overcurrent protection method, which is applied to a line protection device, and the line protection device is used to monitor the line state of a multi-phase distribution line. The method includes: obtaining multiple line voltages and multiple line currents, and the multiple line voltages and multiple line currents correspond to each other. According to a preset unit impedance value, a variable impedance is determined, and the variable impedance amplitude is positively correlated with the preset unit impedance value. The variable impedance amplitude is the amplitude corresponding to the variable impedance, and the preset unit impedance value is positively correlated with the line length of the distribution line. According to the variable impedance, the first line current and the first line voltage, the working voltage is determined, the first line current is any line current greater than or equal to the preset overcurrent threshold value among the multiple line currents, and the first line voltage is the line voltage corresponding to the first line current among the multiple line voltages. According to the working voltage and the polarization voltage, the phase angle is determined. If the phase angle is within the preset angle range, the target action delay is determined according to the variable impedance and the preset action delay, and the target action delay is negatively correlated with the variable impedance amplitude.

[0006] In some embodiments, determining the variable impedance according to the preset unit impedance value includes: obtaining a line impedance angle. Determining the variable impedance according to the line impedance angle, the preset unit impedance value, and the first time period, the variable impedance corresponding to the variable impedance is the same as the line impedance angle, the variable impedance amplitude is positively correlated with the first time period, the start time of the first time period is the first moment, the first moment is the moment when the line protection device detects the start signal, and the end time of the first time period is the current moment.

[0007] In some implementations, determining the variable impedance according to the line impedance angle, the preset unit impedance value, and the first time period includes: determining the quotient of the first time period divided by the sampling period as the amplitude coefficient. Determining the product of the amplitude coefficient and the preset unit impedance value as the variable impedance amplitude. Determining the variable impedance according to the variable impedance amplitude and the line impedance angle.

[0008] In some embodiments, determining a target action delay according to the variable impedance and the preset action delay includes: obtaining a reference impedance. Determining a ratio of the variable impedance amplitude to the reference impedance. Determining an acceleration time of the line protection device according to the ratio and the preset action delay. Determining a target action delay according to the acceleration time and the preset action delay. If the difference between the preset action delay and the acceleration time is greater than or equal to the shortest action delay, determining the target action delay as the difference between the preset action delay and the acceleration time. If the difference between the preset action delay and the acceleration time is less than the shortest action delay, determining the target action delay as the shortest action delay.

[0009] In some implementations, determining the operating voltage based on the variable impedance, the first line current, and the first line voltage includes determining the difference between the first line voltage and the product of the variable impedance and the first line current as the operating voltage.

[0010] In some embodiments, determining the phase angle according to the working voltage and the polarization voltage includes: obtaining the rated voltage amplitude. Determining the minimum voltage amplitude according to the rated voltage amplitude, the minimum voltage amplitude is proportional to the rated voltage amplitude. If multiple line voltages are less than or equal to the minimum voltage amplitude, then determining the polarization voltage according to multiple reference line voltages, the multiple reference line voltages are line voltages collected by the line protection device at a second moment, the second moment is a moment before the first moment when the line protection device detects a start signal, and is separated from the first moment by k sampling cycles, k is an integer greater than 0 and less than 5. If there is a second line voltage greater than the minimum voltage amplitude among the multiple line voltages, then determining the positive sequence voltage corresponding to the first line voltage is the polarization voltage. Determining the angle of the ratio of the working voltage to the polarization voltage is the phase angle.

[0011] In some embodiments, a plurality of reference line voltages correspond one-to-one to a plurality of line voltages, and determining the polarization voltage based on the plurality of reference line voltages includes: obtaining a sampling sequence number corresponding to the first line voltage, the sampling sequence number being used to characterize the number of times the line protection device collects the line voltage after the first moment. Obtaining the number of cycle sampling points. Determining the ratio of 360° to the number of cycle sampling points as the sampling angle step. Determining the product of the sampling angle step and the sampling sequence number, and the sum of the first reference line voltage angle, as the polarization voltage angle corresponding to the polarization voltage, the first reference line voltage being one of the plurality of reference line voltages corresponding to the first line voltage, and the first reference line voltage angle being the angle corresponding to the first reference line voltage. Determining the polarization voltage based on the polarization voltage angle.

[0012] In some embodiments, after determining the target action delay according to the variable impedance and the preset action delay, the method further includes: based on the preset sampling frequency, continuously acquiring multiple groups of second line currents within the second time period, each group of second line currents includes multiple second line currents, the multiple second line currents correspond one-to-one to the multiple line currents, the start time of the second time period is the current time, and the time interval of the second time period is the target action delay. If the multiple target second line currents corresponding to the multiple groups of second line currents are all greater than or equal to the preset overcurrent threshold, a disconnection instruction is sent to the multiple circuit breakers respectively, the target second line current is the line current corresponding to the first line current among the multiple second line currents, the multiple circuit breakers correspond one-to-one to the multi-phase distribution lines, the multiple circuit breakers are used to change the line state of the multi-phase distribution lines, and the disconnection instruction is used to instruct the circuit breaker to change the line state to the disconnected state.

[0013] In a second aspect, the present application provides a distribution line overcurrent protection device, which may be a line protection device, and is used to monitor the line status of a multi-phase distribution line. The device includes: an acquisition module and a determination module.

[0014] The acquisition module is used to acquire multiple line voltages and multiple line currents, and the multiple line voltages and the multiple line currents correspond to each other one by one.

[0015] The determination module is used to determine the variable impedance according to the preset unit impedance value, the variable impedance amplitude is positively correlated with the preset unit impedance value, the variable impedance amplitude is the amplitude corresponding to the variable impedance, and the preset unit impedance value is positively correlated with the line length of the distribution line.

[0016] The determination module is also used to determine the operating voltage based on the variable impedance, the first line current and the first line voltage, wherein the first line current is any line current among multiple line currents that is greater than or equal to a preset overcurrent threshold, and the first line voltage is a line voltage among multiple line voltages corresponding to the first line current.

[0017] The determination module is also used to determine the phase angle according to the working voltage and the polarization voltage. If the phase angle is within the preset angle range, the target action delay is determined according to the variable impedance and the preset action delay, and the target action delay is negatively correlated with the variable impedance amplitude.

[0018] In a third aspect, the present application provides an electronic device, comprising a processor and a memory, wherein the processor is configured to execute a computer program stored in the memory to implement a method as described in any one of the first aspects above.

[0019] In a fourth aspect, the present application provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, it implements the method as described in any one of the first aspects above.

[0020] In the technical solution provided by the present application, the line protection device can obtain multiple line voltages and multiple line currents in real time, and determine the variable impedance according to the preset unit impedance value, the variable impedance amplitude is positively correlated with the preset unit impedance value, and the preset unit impedance value is positively correlated with the line length of the distribution line. And based on the preset overcurrent threshold, determine the working voltage corresponding to the fault phase distribution line. Then determine the phase angle according to the working voltage and the polarization voltage. If the phase angle is within the preset angle range, the target action delay is determined according to the variable impedance and the preset action delay, and the target action delay is negatively correlated with the variable impedance amplitude. Ensure that the target action delay corresponding to the line protection device closest to the fault point is the smallest, so that the action delays corresponding to each line protection device can be reliably distinguished, so as to increase the number of target action delays that can be set within the preset action delay range, thereby increasing the number of line protection devices put into overcurrent protection. After the line protection device closest to the fault point is actuated, the fault range can be reduced and the impact of the line fault on the power system can be reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 It is a schematic diagram of an arrangement structure of a line protection device provided in an embodiment of the present application; Figure 2 It is a schematic diagram of a circuit device for actual step-by-step coordination provided in an embodiment of the present application; Figure 3 It is a flowchart of a fault identification method provided in an embodiment of the present application; Figure 4 It is a flow chart of a distribution line overcurrent protection method provided in an embodiment of the present application; Figure 5 It is a schematic diagram of a distribution line overcurrent protection device provided in an embodiment of the present application; Figure 6 It is a schematic diagram of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0023] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present application. However, it should be clear to those skilled in the art that the present application may also be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, devices, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present application.

[0024] It should be understood that when used in the present specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or combinations thereof.

[0025] It should also be understood that the term “and / or” used in the specification and appended claims refers to any and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0026] As used in the specification and appended claims of this application, the term "if" can be interpreted as "when" or "uponce" or "in response to determining" or "in response to detecting", depending on the context. Similarly, the phrase "if it is determined" or "if [described condition or event] is detected" can be interpreted as meaning "uponce it is determined" or "in response to determining" or "uponce [described condition or event] is detected" or "in response to detecting [described condition or event]", depending on the context.

[0027] In addition, in the description of the present application specification and the appended claims, the terms "first", "second", "third", etc. are only used to distinguish the descriptions and cannot be understood as indicating or implying relative importance.

[0028] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that one or more embodiments of the present application include specific features, structures or characteristics described in conjunction with the embodiment. Therefore, the statements "in one embodiment", "in some embodiments", "in some other embodiments", "in some other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "including", "comprising", "having" and their variations all mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0029] Overcurrent protection step coordination is a common protection strategy in power systems, which aims to achieve selective protection by setting the action delay and overcurrent threshold of the line protection device in a graded manner. This ensures that when a fault occurs, the line protection device closest to the fault point will act first, thereby quickly isolating the fault and minimizing the scope of the power outage.

[0030] The overcurrent protection step coordination includes the overcurrent threshold (also called current setting or overcurrent setting) step coordination and the action delay step coordination. Among them, the overcurrent threshold refers to the overcurrent threshold set on the line protection device, which changes step by step from the power supply side to the load side. The overcurrent threshold set on the line protection device close to the head end (power supply) is the largest, the overcurrent threshold set on the middle line protection device decreases in sequence, and the overcurrent threshold set on the line protection device close to the end (load) is the smallest.

[0031] For example, Figure 1A schematic diagram of a line protection device arrangement architecture provided in an embodiment of the present application. The grid side is the power supply side, and line protection device 1, line protection device 2, line protection device 3, ... line protection device N are installed in sequence from the grid side to the load side. The overcurrent threshold corresponding to line protection device 1 is the largest, and the overcurrent threshold corresponding to line protection device N is the smallest. The overcurrent thresholds corresponding to the line protection devices between line protection device 1 and line protection device N decrease in sequence.

[0032] The step-by-step coordination of the action delay means that the action delay set on the line protection device changes step by step from the power supply side to the load side. The action delay set on the line protection device close to the head end (power supply) is the longest, the action delay set on the middle line protection device decreases in sequence, and the action delay set on the line protection device close to the end (load) is the shortest.

[0033] For example, see Figure 1 , the line protection device 1 to the line protection device N are set with the same overcurrent threshold, the action delay corresponding to the line protection device 1 is the largest, the action delay corresponding to the line protection device N is the smallest, and the action delays corresponding to the line protection devices between the line protection device 1 and the line protection device N decrease in sequence.

[0034] However, since distribution lines are usually short, when a distribution line fault occurs, the difference in fault current collected by each line protection device on the distribution line is usually small, making it difficult to achieve step-by-step coordination of overcurrent thresholds.

[0035] For example, see Figure 1 , line protection devices 1 to N divide the distribution line into multiple line segments, namely, distribution line 1, distribution line 2, distribution line 3...distribution line N. Multiple line protection devices correspond to multiple line segments one by one. When a fault occurs at point F1, ideally, line protection device 2 removes the fault, which can minimize the fault range. However, since the fault currents collected by line protection devices 1 to N are slightly different, it is impossible to determine which line protection device removes the fault, making it difficult to achieve step-by-step coordination of overcurrent thresholds.

[0036] In addition, in order to ensure the rapidity of fault removal, the action delay set on the line protection device close to the head end (power supply) cannot be too long, and the difference between the action delays set on each line protection device must be large, so that the action delays on each line protection device can be reliably distinguished to achieve step-by-step coordination of action delays. Therefore, within a certain action delay threshold range, the number of step-by-step action delays that can be set is small, and the number of line protection devices that are actually put into step-by-step coordination on the line is small.

[0037] For example, for Figure 1For each line protection device in the circuit, the corresponding action delay of the line protection device is changed obviously in a step-by-step manner. Figure 1 The line protection devices that are actually put into step coordination are as follows: Figure 2 As shown, Figure 2 The line protection device M in Figure 1 The line protection device corresponding to the line protection device closest to the middle of the line, line protection device 1, line protection device M and line protection device N correspond to distribution line 1, distribution line M and distribution line N respectively.

[0038] When the line protection device investment is small, the distance between the distribution lines corresponding to each line protection is longer. Figure 2 If a fault occurs at point F2, the line protection device M will remove the fault, but the fault range after isolation is large. The larger the fault range, the greater the impact on the power system.

[0039] In view of this, an embodiment of the present application provides a distribution line overcurrent protection method, which can determine the action delay corresponding to the line protection device, so that the action delay corresponding to each line protection device can be reliably distinguished, thereby increasing the number of line protection devices put into step-by-step coordination, so as to narrow the fault scope and reduce the impact of line faults on the power system.

[0040] The technical solution of the embodiments of the present application is described below with reference to the examples in the accompanying drawings.

[0041] Figure 3 This is a flow chart of a fault identification method provided in an embodiment of the present application. The line protection device can perform fault identification by calculating the action delay. It includes the following steps: Step S301: Acquire a plurality of line voltages and a plurality of line currents, wherein the plurality of line voltages and the plurality of line currents correspond to each other one by one.

[0042] In the technical solution provided in the embodiment of the present application, the line protection device can obtain multiple phase voltages and multiple phase currents corresponding to the multi-phase distribution line in real time, and calculate multiple line voltages and multiple line currents based on the multiple phase voltages and multiple phase currents.

[0043] In the embodiment of the present application, the multiple phase voltages and the multiple phase currents may be phase voltages and phase currents corresponding to the three-phase distribution lines in a three-phase system.

[0044] For example, see Figure 1 , the line protection device can be Figure 1 When the line protection device is the line protection device 2, the multi-phase distribution line can be a three-phase line corresponding to the distribution line 2, the multiple phase voltages are the three phase voltages corresponding to the distribution line 2, and the multiple phase currents can be the three phase currents corresponding to the distribution line 2.

[0045] For example, the multi-phase distribution lines can be phase A, phase B, and phase C. The multiple phase voltages are: the voltage of phase A, the voltage of phase B, and the voltage of phase C, respectively expressed as: U A , U B and U C The multiple phase currents can be: the current flowing through the A phase line, the current flowing through the B phase line, and the current flowing through the C phase line, respectively expressed as: I A ,I B and I C .

[0046] In the embodiment of the present application, the line protection device can make a difference between any two voltages among the multiple phase voltages to obtain multiple line voltages, and make a difference between any two currents among the multiple phase currents to obtain multiple line currents.

[0047] For example, the multiple line voltages may be: the voltage between the A phase line and the B phase line, the voltage between the B phase line and the C phase line, and the voltage between the C phase line and the A phase line, respectively expressed as: U AB , U BC and U CA .

[0048] Among them, U AB =U A -U B ; U BC =U B -U C ; U CA =U C -U A ; The multiple line currents can be respectively: the difference between the current in the wire corresponding to the A phase line and the current in the wire corresponding to the B phase line, the difference between the current in the wire corresponding to the B phase line and the current in the wire corresponding to the C phase line, and the difference between the current in the wire corresponding to the C phase line and the current in the wire corresponding to the A phase line, which are respectively expressed as: I AB ,I BC and I CA .

[0049] Among them, I AB =I A -I B ; I BC =I B -I C ; I CA =I C -IA .

[0050] Step S302: when the line protection device detects a start signal, the moment when the start signal is detected is recorded as a first moment, and a plurality of reference line voltages are obtained, where the plurality of reference line voltages are line voltages obtained by the line protection device at a second moment.

[0051] When the line protection device does not detect the start signal, it indicates that the distribution line in the power system is in normal operation, and the line protection device does not need to perform fault identification to save the computing power of the line protection device. When the line protection device detects the start signal, it indicates that there may be a fault in the distribution line in the power system, and the line protection device starts fault identification and executes the protection process.

[0052] During the normal operation of the line protection device, the angle of the line voltage collected is usually close to the line voltage angle collected one sampling cycle or several sampling cycles ago. And when a distribution line fails (after the line protection device detects the start signal), the line voltage corresponding to the distribution line may change significantly. Therefore, the line protection device can use the line voltage angle collected k sampling cycles ago as the angle of the power supply potential. That is, the second moment is before the first moment, and is separated from the first moment by k sampling cycles. In the embodiment of the present application, k can be an integer greater than 0 and less than 5.

[0053] For example, when k is 2 and the sampling period is 20 ms, the multiple reference line voltages may be multiple reference line voltages collected by the line protection device 40 ms before the first moment, denoted as U 3AB , U 3BC and U 3CA .

[0054] Step S303: Determine the faulty phase distribution line according to a preset overcurrent threshold.

[0055] In the embodiment of the present application, the line protection device can continuously determine the faulty phase distribution line according to the sampling frequency of the line voltage and the line current after detecting the start signal.

[0056] Exemplarily, after the line protection device detects the start signal at time T1 (i.e., the first time), the line current corresponding to the line current greater than the preset overcurrent threshold value obtained at the time T1 can be determined as the fault phase distribution line. It can be understood that the fault phase distribution line can be one phase or multiple phases, and this application does not limit this.

[0057] For example, the preset overcurrent threshold is I set , the multiple line currents obtained by the line protection device at time T1 are I 1AB ,I 1BCand I 1CA , if I 1AB >I set , I 1BC >I set And I 1CA <I set , the line protection device can determine that the faulty phase distribution lines are the AB phase line and the BC phase line. The line protection device performs fault discrimination on the AB phase line and the BC phase line respectively. The embodiment of the present application uses the discrimination process of the line protection device on one of the faulty phase distribution lines as an example. It should be understood that the discrimination process of the line protection device on the other phase faulty phase distribution lines has the same or similar discrimination principle as the fault discrimination process provided in the embodiment of the present application.

[0058] The line protection device obtains multiple line currents I and I at time T2 (a sampling time after the first time and adjacent to the first time) according to the preset sampling frequency. 2AB ,I 2BC and I 2CA , if I 2AB >I set , I 2BC >I set And I 2CA <I set , the line protection device can determine that the AB phase line and the BC phase line are still the fault phase distribution lines at time T2.

[0059] Step S304: Determine the operating voltage corresponding to the faulty phase distribution line.

[0060] At the first moment and after the first moment, the line protection device can calculate the working voltage corresponding to the fault phase distribution line in real time according to the acquired multiple line voltages and multiple line currents. The method for the line protection device to calculate the working voltage can be: Step A1: Calculate the variable impedance.

[0061] In the embodiment of the present application, the variable impedance The calculation formula can be: ; Wherein, n represents the amplitude coefficient, and the line protection device can determine the amplitude coefficient according to the time difference between the current moment and the first moment.

[0062] If the current moment is separated from the first moment by a first time period, the line protection device determines the quotient of the first time period divided by the sampling period as the amplitude coefficient. That is, the amplitude coefficient is used to represent the number of integer cycles between the current line voltage or current and the line voltage or current collected at the first moment.

[0063] For example, if the sampling period is 20ms, the first time period is 40ms, n=40ms / 20ms=2, and the line protection device determines that the amplitude coefficient n is 2. If the time interval between the sampling time of the current line voltage or line current and the first moment is 70ms, n=70ms / 20ms=3...10ms, and the line protection device determines that n is 3. If the current moment is the first moment and the first time period is 0, then n is 0.

[0064] Indicates a preset unit impedance value, that is, an impedance value corresponding to a unit distribution line. The line protection device may set a preset unit impedance value according to the length of the distribution line. The preset unit impedance value may be positively correlated with the length of the distribution line corresponding to the line protection device.

[0065] For example, see Figure 1 , the preset unit impedance value can be the impedance value corresponding to 0.25 times the length of the distribution line corresponding to the line protection device. For example, if the line protection device is line protection device 2, then its corresponding distribution line is distribution line 2. If the line length corresponding to distribution line 2 is 4km, the line protection device can set the preset unit impedance value to the impedance value corresponding to each 1km distribution line. If the line protection device is line protection device 3, the corresponding distribution line is distribution line 3. If the line length corresponding to distribution line 3 is 2km, the line protection device can set the preset unit impedance value to the impedance value corresponding to each 500m distribution line. The specific method for setting the preset unit impedance value is not limited in the embodiment of the present application.

[0066] It represents the amplitude corresponding to the variable impedance, that is, the variable impedance amplitude coefficient X.

[0067] It represents the line impedance angle, that is, the impedance angle corresponding to the distribution line, which is a known constant.

[0068] Indicates the angle corresponding to the variable impedance (variable impedance angle).

[0069] Step A2: Determine the operating voltage corresponding to the fault phase distribution line according to the variable impedance.

[0070] In the embodiment of the present application, the working voltage The calculation formula can be: ; in, Indicates the line voltage corresponding to the fault phase distribution line, Indicates the line current corresponding to the fault phase distribution line, Indicates variable impedance.

[0071] For example, if the fault phase distribution line is the AB phase line, then Can be the line current I corresponding to the AB phase line AB , is the line voltage U corresponding to the AB phase line AB ,Right now .

[0072] Step S305: Determine the polarization voltage corresponding to the fault phase distribution line.

[0073] In an embodiment of the present application, a method for a line protection device to determine a polarization voltage may include the following steps: Step B1: Perform low voltage determination based on multiple line voltages.

[0074] In the embodiment of the present application, the line protection device can determine whether multiple line voltages are all low voltages. If multiple line voltages are all low voltages, the line protection device determines the polarization voltage based on multiple reference line voltages; if there is a line voltage that is not a low voltage among the multiple line voltages, the line protection device directly calculates the polarization voltage based on the multiple line voltages.

[0075] The line protection device can determine the minimum voltage amplitude according to the rated voltage amplitude. The minimum voltage amplitude can be proportional to the rated voltage amplitude. For example, the minimum voltage amplitude can be 0.05 times the rated voltage amplitude, and the present application does not limit the specific value of the minimum voltage amplitude. And judge whether multiple line voltages are all less than the minimum voltage amplitude, so as to determine whether multiple line voltages are all low voltages.

[0076] Step B2: If the multiple line voltages are all less than the minimum voltage amplitude, then determine the polarization voltage according to the multiple reference line voltages.

[0077] If multiple line voltages are all less than the minimum voltage amplitude, the line protection device determines that the multiple line voltages are all low voltages. Multiple line voltages are all less than the minimum voltage amplitude, which means that the multiple line voltages are all very small, and the multiple line voltages are all close to 0, and the line protection device is difficult to determine the voltage angles of the multiple line voltages. Therefore, the line protection device can determine the polarization voltage based on multiple reference line voltages.

[0078] The method for the line protection device to determine the polarization voltage according to multiple reference line voltages may be: Step B2-1: Calculate the polarization voltage angle.

[0079] Polarization voltage angle The calculation formula can be: ; in, Indicates the angle of the reference line voltage corresponding to the fault phase distribution line, that is, the reference line voltage angle. For example, if the fault phase distribution line is the AB phase line, It means that among the multiple reference line voltages obtained by the line protection device at the second moment, the reference line voltage U corresponding to the AB phase line 1AB The angle of for .

[0080] M represents the sampling sequence number of the baseline voltage corresponding to the fault phase distribution line. The line protection device can record the sampling sequence number of each sampling starting from the first moment. Exemplarily, the sampling sequence number of the first moment sampling can be recorded as 0, and the sampling sequence number of the next sampling after the first moment can be recorded as 1. For each subsequent sampling, the sampling sequence is added by 1 to record the sampling sequence number corresponding to each sampling after the first moment. For example, if the current sampling is the 50th sampling after the first moment by the line protection device according to the sampling frequency, then M=50.

[0081] It represents the sampling angle step, which is the ratio of 360° to the number of sampling points in a cycle. It can be understood that if the line protection device samples according to the sampling frequency, the sampling angle will change 360° after one sampling cycle. If the line protection device samples S times in one sampling cycle, the sampling angle will change every time it is sampled. times, that is .

[0082] It is understandable that in In the process of normal operation of the line protection device, the line voltage angle collected is usually close to the line voltage angle collected one sampling cycle or several sampling cycles ago. Then it can represent the angle of the power supply potential corresponding to the first moment. It is used to indicate the angle change of the line voltage in the first time period (the time period from the first moment to the current moment). Therefore, It can represent the polarization voltage angle at the current moment.

[0083] Step B2-2: Calculate the polarization voltage according to the polarization voltage angle.

[0084] In the embodiment of the present application, if the multiple line voltages are all less than the minimum voltage amplitude, the amplitude corresponding to the polarization voltage can be set to a smaller constant. For example, the amplitude corresponding to the polarization voltage can be 1, that is, the polarization voltage Can be , Indicates the angle corresponding to the polarization voltage.

[0085] Step B3: If there is a line voltage greater than or equal to the minimum voltage amplitude among the multiple line voltages, calculate the polarization voltage based on the multiple line voltages.

[0086] The line protection device can determine the positive sequence voltage corresponding to the fault phase distribution line as the polarization voltage.

[0087] For example, if the fault phase distribution line is the AB phase line, the polarization voltage The calculation formula can be: ; Among them, U AB Indicates the line voltage corresponding to the AB phase line obtained at the current moment, U CA It is used to indicate the line voltage corresponding to the CA phase line obtained at the current moment, U BC represents the line voltage corresponding to the BC phase line obtained at the current moment, a represents the positive sequence rotation factor, .

[0088] Step S306: Determine the target action delay according to the working voltage and the polarization voltage.

[0089] In the embodiment of the present application, after determining the operating voltage and the polarization voltage, the line protection device can determine the target action delay corresponding to the line protection device according to the operating voltage and the polarization voltage.

[0090] The method for determining the target action delay of the line protection device according to the working voltage and the polarization voltage may include: Step C1: Determine the phase angle according to the operating voltage and the polarization voltage.

[0091] Phase Angle The calculation formula can be: ; in, Indicates the operating voltage, represents the polarization voltage, The angle that represents the ratio of the operating voltage to the polarization voltage, also known as the phase angle.

[0092] Step C2: If the phase angle is within the preset angle range, the acceleration time of the line protection device is determined according to the amplitude coefficient of the variable impedance.

[0093] In the embodiment of the present application, the preset angle range may be a preset negative angle range. For example, the preset angle range may be (125°, 325°), that is, if 125° < <325°, the line protection device determines the acceleration time of the line protection device according to the amplitude coefficient of the variable impedance.

[0094] In some embodiments, the preset angle range may also be (90°, 270°) or other preset angle ranges, which is not limited in the present application.

[0095] Acceleration time The calculation formula can be: ; in, Indicates the preset action delay. In the embodiment of the present application, the preset action delays corresponding to the line protection devices on the power distribution line of the power system may be the same. For example, the preset action delays may all be set to 500ms.

[0096] X represents the amplitude coefficient of variable impedance, i.e. variable impedance The corresponding amplitude coefficient .

[0097] Z represents the reference impedance, which is a known constant. The line protection device can determine the reference impedance according to the empirical impedance value of the corresponding distribution line, for example, according to the impedance value of the length of the distribution line corresponding to the line protection device, which is not limited in this application.

[0098] Step C2: Determine the target action delay according to the acceleration time.

[0099] Target action delay The calculation formula can be: ; That is, the target action delay To preset action delay and acceleration time difference.

[0100] It can be understood that the closer the line protection device is to the fault point, the smaller the amplitude coefficient X of the variable impedance. middle, is a constant. The smaller X is, the The smaller; The smaller the The bigger; The larger the The larger it is, the smaller X is. The bigger. Because, , The larger the value, the longer the target action will be delayed. It should be understood that the closer the line protection device is to the fault point, the smaller the target action delay calculated by the embodiment of the present application.

[0101] In some embodiments, to ensure the effectiveness of fault removal, the target action delay cannot be too small. The line protection device can be set with a minimum action delay If the difference between the preset action delay and the acceleration time is greater than or equal to the shortest action delay, the target action delay is determined to be the difference between the preset action delay and the acceleration time; if the difference between the preset action delay and the acceleration time is less than the shortest action delay, the target action delay is determined to be the shortest action delay.

[0102] Step S307: Determine the fault judgment result according to the target action delay.

[0103] In the embodiment of the present application, after the line protection device detects the start signal, based on the preset sampling frequency, multiple groups of second line currents are continuously obtained within the second time period, each group of second line currents includes multiple second line currents, the multiple second line currents correspond one-to-one to the multiple line currents, the starting time of the second time period is the current time, and the time interval of the second time period is the target action delay. If the multiple target second line currents corresponding to the multiple groups of second line currents are all greater than or equal to the preset overcurrent threshold, disconnection instructions are sent to the multiple circuit breakers respectively, the target second line current is the line current corresponding to the first line current among the multiple second line currents, the multiple circuit breakers correspond one-to-one to the multi-phase distribution lines, the multiple circuit breakers are used to change the line state of the multi-phase distribution lines, and the disconnection instruction is used to instruct the circuit breaker to change the line state to the disconnected state.

[0104] In the technical solution provided by the embodiment of the present application, each line protection device in the power system is provided with the same preset action delay, the shortest action delay and the preset overcurrent threshold. For any one of the multiple line protection devices, after detecting the start signal, the line protection device can determine the fault phase distribution line according to the preset overcurrent threshold. For any phase fault phase distribution line, the line protection device can calculate the variable impedance, thereby determining the working voltage according to the variable impedance, and calculating the polarization voltage, and determining the target action delay corresponding to the line protection device according to the working voltage and the polarization voltage. The closer the line protection device is to the fault point, the shorter its corresponding target action delay is. When the line current corresponding to the fault phase distribution line continues to be greater than or equal to the preset overcurrent threshold within the target action delay, the line protection device can send disconnection instructions to the corresponding multiple circuit breakers to disconnect the line. Ensure that the line protection action closest to the fault point is executed first to cut off the fault, minimize the fault range, and improve the reliability of the power system operation.

[0105] Corresponding to the fault identification method provided in the above steps S301 to S307, the embodiment of the present application provides a distribution line overcurrent protection method, such as Figure 4 As shown, the following steps may be included: Step S401: Acquire a plurality of line voltages and a plurality of line currents, wherein the plurality of line voltages and the plurality of line currents correspond to each other one by one.

[0106] In an embodiment of the present application, the multiple line voltages and the multiple line currents may be three line voltages and three line currents collected by a line protection device in a three-phase system, namely, the line voltage and line current corresponding to the AB phase line, the line voltage and line current corresponding to the BC phase line, and the line voltage and line current corresponding to the CA phase line.

[0107] For specific acquisition methods, please refer to Figure 3 In the corresponding embodiment, the line protection device obtains the corresponding descriptions of multiple line voltages and multiple line currents, which will not be elaborated in this application.

[0108] Step S402: determining a variable impedance according to a preset unit impedance value, wherein the variable impedance amplitude is positively correlated with the preset unit impedance value, the variable impedance amplitude is the amplitude corresponding to the variable impedance, and the preset unit impedance value is positively correlated with the line length of the distribution line.

[0109] The preset unit impedance value may be a known impedance value. The method for determining the variable impedance of the line protection device according to the preset unit impedance value may refer to Figure 3 In the corresponding embodiment, the line protection device determines the description corresponding to the variable impedance according to the preset unit impedance value, which is not elaborated in this application.

[0110] Step S403: Determine the operating voltage according to the variable impedance, the first line current and the first line voltage, wherein the first line current is any line current among multiple line currents that is greater than or equal to a preset overcurrent threshold, and the first line voltage is a line voltage among multiple line voltages corresponding to the first line current.

[0111] The line protection device can determine the difference between the first line voltage and the product of the variable impedance and the first line current as the operating voltage. The specific calculation method can refer to Figure 3 In the corresponding embodiment, the line protection device determines the description of the operating voltage according to the variable impedance, the first line current and the first line voltage, which is not elaborated in this application.

[0112] Step S404: Determine the phase angle according to the operating voltage and the polarization voltage.

[0113] The phase angle can be the angle of the ratio of the working voltage to the polarization voltage. The specific calculation method of the phase angle can refer to Figure 3 In the corresponding embodiment, the description of determining the phase angle by the line protection device is not repeated in this application.

[0114] Step S405: If the phase angle is within the preset angle range, a target action delay is determined according to the variable impedance and the preset action delay, and the target action delay is negatively correlated with the variable impedance amplitude.

[0115] The line protection device can implement overcurrent protection according to the target action delay and the preset overcurrent threshold. The specific calculation method of the target action delay can be referred to Figure 3 In the corresponding embodiment, the description of the line protection device determining the target action delay is not repeated in this application.

[0116] In the technical solution provided by the embodiment of the present application, the line protection device can obtain multiple line voltages and multiple line currents in real time, and determine the variable impedance according to the preset unit impedance value, the variable impedance amplitude is positively correlated with the preset unit impedance value, and the preset unit impedance value is positively correlated with the line length of the distribution line. Based on the preset overcurrent threshold, the working voltage corresponding to the fault phase distribution line is determined. Then, the phase angle is determined according to the working voltage and the polarization voltage. If the phase angle is within the preset angle range, the line protection device determines the target action delay according to the variable impedance and the preset action delay, and the target action delay is negatively correlated with the variable impedance amplitude. To ensure that the target action delay corresponding to the line protection device closest to the fault point is the smallest, so that the action delays corresponding to each line protection device can be reliably distinguished, and the number of target action delays that can be set within the preset action delay range is increased, thereby increasing the number of line protection devices that are put into overcurrent protection. After the line protection device closest to the fault point is actuated, the fault range can be reduced, and the impact of the line fault on the power system can be reduced.

[0117] It should be understood that, under the premise of no logical conflict, the above-mentioned various application embodiments can be implemented in combination with each other to meet actual application requirements. The specific embodiments or implementation plans obtained after these combinations still fall within the protection scope of this application.

[0118] Corresponding to the distribution line overcurrent protection method in the above embodiment, the embodiment of the present application provides a distribution line overcurrent protection device 50, which can be a line protection device. The distribution line overcurrent protection device 50 can be implemented by software, hardware, or a combination of both to become part or all of a computer device, and is used to execute the steps in the distribution line overcurrent protection method in the above embodiment.

[0119] Figure 5 A schematic structural diagram of a distribution line overcurrent protection device provided in an embodiment of the present application is shown. For ease of explanation, only the parts related to the embodiment of the present application are shown.

[0120] Reference Figure 5 The distribution line overcurrent protection device 50 includes an acquisition module 510 and a determination module 520 .

[0121] The acquisition module 510 is used to acquire a plurality of line voltages and a plurality of line currents, where the plurality of line voltages and the plurality of line currents correspond to each other one by one.

[0122] The determination module 520 is used to determine the variable impedance according to the preset unit impedance value, the variable impedance amplitude is positively correlated with the preset unit impedance value, the variable impedance amplitude is the amplitude corresponding to the variable impedance, and the preset unit impedance value is positively correlated with the line length of the distribution line.

[0123] The determination module 520 is also used to determine the operating voltage based on the variable impedance, the first line current and the first line voltage, wherein the first line current is any line current among multiple line currents that is greater than or equal to a preset overcurrent threshold, and the first line voltage is a line voltage among multiple line voltages corresponding to the first line current.

[0124] The determination module 520 is further used to determine the phase angle according to the working voltage and the polarization voltage. If the phase angle is within the preset angle range, the target action delay is determined according to the variable impedance and the preset action delay, and the target action delay is negatively correlated with the variable impedance amplitude.

[0125] In some embodiments, the determination module 520 is specifically used to: obtain the line impedance angle. According to the line impedance angle, the preset unit impedance value and the first time period, the variable impedance is determined, the variable impedance angle corresponding to the variable impedance is the same as the line impedance angle, the variable impedance amplitude is positively correlated with the first time period, the start time of the first time period is the first time, the first time is the time when the line protection device detects the start signal, and the end time of the first time period is the current time.

[0126] In some embodiments, the determination module 520 is specifically configured to: determine the quotient of the first time period divided by the sampling period as the amplitude coefficient, determine the product of the amplitude coefficient and the preset unit impedance value as the variable impedance amplitude, and determine the variable impedance according to the variable impedance amplitude and the line impedance angle.

[0127] In some embodiments, the determination module 520 is specifically used to: obtain a reference impedance. Determine a ratio of the variable impedance amplitude to the reference impedance. Determine an acceleration time of the line protection device according to the ratio and a preset action delay. Determine a target action delay according to the acceleration time and the preset action delay. If the difference between the preset action delay and the acceleration time is greater than or equal to the shortest action delay, determine the target action delay as the difference between the preset action delay and the acceleration time. If the difference between the preset action delay and the acceleration time is less than the shortest action delay, determine the target action delay as the shortest action delay.

[0128] In some embodiments, the determination module 520 is specifically used to determine that the difference between the first line voltage and the product of the variable impedance and the first line current is the operating voltage.

[0129] In some embodiments, the determination module 520 is specifically used to: obtain the rated voltage amplitude. According to the rated voltage amplitude, the minimum voltage amplitude is determined, and the minimum voltage amplitude is proportional to the rated voltage amplitude. If multiple line voltages are less than or equal to the minimum voltage amplitude, the polarization voltage is determined according to multiple reference line voltages, and the multiple reference line voltages are line voltages collected by the line protection device at the second moment, and the second moment is before the first moment when the line protection device detects the start signal, and is separated from the first moment by k sampling cycles, and k is an integer greater than 0 and less than 5. If there is a second line voltage greater than the minimum voltage amplitude among the multiple line voltages, the positive sequence voltage corresponding to the first line voltage is determined to be the polarization voltage. The angle of the ratio of the working voltage to the polarization voltage is determined to be the phase angle.

[0130] In some embodiments, the determination module 520 is specifically used to: obtain a sampling sequence number corresponding to the first line voltage, the sampling sequence number is used to characterize the number of times the line protection device collects the line voltage after the first moment. Obtain the number of cycle sampling points. Determine the ratio of 360° to the number of cycle sampling points as the sampling angle step. Determine the product of the sampling angle step and the sampling sequence number, and the sum of the first reference line voltage angle, as the polarization voltage angle corresponding to the polarization voltage, the first reference line voltage is one of the multiple reference line voltages corresponding to the first line voltage, and the first reference line voltage angle is the angle corresponding to the first reference line voltage. Determine the polarization voltage according to the polarization voltage angle.

[0131] In some embodiments, the determination module 520 is further used to: based on a preset sampling frequency, continuously obtain multiple groups of second line currents within a second time period, each group of second line currents includes multiple second line currents, the multiple second line currents correspond one-to-one to the multiple line currents, the start time of the second time period is the current time, and the time interval of the second time period is the target action delay. If the multiple target second line currents corresponding to the multiple groups of second line currents are all greater than or equal to the preset overcurrent threshold, a disconnection instruction is sent to the multiple circuit breakers respectively, the target second line current is the line current corresponding to the first line current among the multiple second line currents, the multiple circuit breakers correspond one-to-one to the multi-phase distribution lines, the multiple circuit breakers are used to change the line state of the multi-phase distribution lines, and the disconnection instruction is used to instruct the circuit breaker to change the line state to the disconnected state.

[0132] It should be noted that the information interaction, execution process, etc. between the above-mentioned devices / units are based on the same concept as the method embodiment of the present application. Their specific functions and technical effects can be found in the method embodiment part and will not be repeated here.

[0133] It should be understood that the size of the serial numbers of the steps in the above embodiments does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0134] Based on the same inventive concept, an embodiment of the present application also provides an electronic device.

[0135] Figure 6 Schematic diagram of the structure of the electronic device provided in the embodiment of the present application. Figure 6 As shown, the electronic device 60 of this embodiment includes: at least one processor 610 ( Figure 6 Only one is shown in the figure), memory 620, and communication module 640, memory 620 stores computer program 630 that may be run on processor 610. When processor 610 executes computer program 630, steps in the above-mentioned distribution line overcurrent protection method embodiment are implemented, such as Figure 3 Alternatively, when the processor 610 executes the computer program 630, the functions of each module / unit in the above-mentioned device embodiments are implemented, for example, Figure 5 The functions of the modules 510 to 520 are shown, and the communication module 640 can be a separate communication unit for communicating with an external server or terminal device.

[0136] The electronic device 60 may include, but is not limited to: a processor 610 and a memory 620. Those skilled in the art will appreciate that Figure 6 It is only an example of the electronic device 60 and does not constitute a limitation of the electronic device 60. It may include more or fewer components than shown in the figure, or a combination of certain components, or different components. For example, the electronic device 60 may also include an input sending device, a network access device, a bus, etc.

[0137] The processor 610 may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field-programmable gate arrays (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may be any conventional processor, etc.

[0138] In some embodiments, the memory 620 may be an internal storage unit of the electronic device 60, such as a hard disk or memory of the electronic device 60. The memory 620 may also be an external storage device of the electronic device 60, such as a plug-in hard disk, a smart media card (SMC), a secure digital (SD) card, a flash card, etc. equipped on the electronic device 60. The memory 620 may also include both an internal storage unit of the electronic device 60 and an external storage device. The memory 620 is used to store an operating system, an application program, a boot loader (BootLoader), data, and other programs, such as program codes of a computer program 630. The memory 620 may also be used to temporarily store data that has been sent or is to be sent.

[0139] In addition, those skilled in the art can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example. In actual applications, the above-mentioned functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units in each embodiment of the present application can be integrated into a processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units.

[0140] An embodiment of the present application provides a computer-readable storage medium, which stores a computer program. When the computer program runs on an electronic device, the electronic device executes the steps in the above-mentioned method embodiments.

[0141] An embodiment of the present application provides a chip, which includes a processor and a memory. The memory stores a computer program, and when the computer program is executed by the processor, the steps in the above-mentioned method embodiments are implemented.

[0142] An embodiment of the present application provides a computer program product. When the computer program product is run on an electronic device, the electronic device executes the steps in the above-mentioned method embodiments.

[0143] It should be understood that the processor mentioned in the embodiments of the present application may be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), field programmable gate arrays (FPGA) or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components, etc. A general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0144] It should also be understood that the memory mentioned in the embodiments of the present application may be a volatile memory or a non-volatile memory, or may include both volatile and non-volatile memories. Among them, the non-volatile memory may be a read-only memory (ROM), a programmable read-only memory (PROM), an erasable programmable read-only memory (EPROM), an electrically erasable programmable read-only memory (EEPROM), or a flash memory. The volatile memory may be a random access memory (RAM), which is used as an external cache. By way of example and not limitation, many forms of RAM are available, such as static random access memory (SRAM), dynamic random access memory (DRAM), synchronous dynamic random access memory (SDRAM), double data rate synchronous dynamic random access memory (DDR SDRAM), enhanced synchronous dynamic random access memory (ESDRAM), synchronous link dynamic random access memory (SLDRAM), and direct memory bus random access memory (Direct Rambus RAM, DR RAM).

[0145] The technicians in the relevant field can clearly understand that for the convenience and simplicity of description, only the division of the above-mentioned functional units and modules is used as an example for illustration. In practical applications, the above-mentioned function allocation can be completed by different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above. The functional units and modules in the embodiment can be integrated in a processing unit, or each unit can exist physically separately, or two or more units can be integrated in one unit. The above-mentioned integrated unit can be implemented in the form of hardware or in the form of software functional units. In addition, the specific names of the functional units and modules are only for the convenience of distinguishing each other, and are not used to limit the scope of protection of this application. The specific working process of the units and modules in the above-mentioned system can refer to the corresponding process in the aforementioned method embodiment, which will not be repeated here.

[0146] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0147] Those of ordinary skill in the art will appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0148] In the embodiments provided in the present application, it should be understood that the disclosed devices and methods can be implemented in other ways. For example, the system embodiments described above are merely schematic. For example, the division of the modules or units is only a logical function division. There may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, devices or units, which can be electrical, mechanical or other forms.

[0149] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0150] In addition, each functional unit in each embodiment of the present application may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0151] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the present application implements all or part of the processes in the above-mentioned embodiment method, which can be completed by instructing the relevant hardware through a computer program, and the computer program can be stored in a computer-readable storage medium. When the computer program is executed by the processor, the steps of the above-mentioned various method embodiments can be implemented. Among them, the computer program includes computer program code, and the computer program code can be in source code form, object code form, executable file or some intermediate form. The computer-readable medium may at least include: any entity or device that can carry the computer program code to a large-screen device, a recording medium, a computer memory, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), an electric carrier signal, a telecommunication signal, and a software distribution medium. For example, a USB flash drive, a mobile hard disk, a magnetic disk or an optical disk. In some jurisdictions, according to legislation and patent practice, computer-readable media cannot be electric carrier signals and telecommunication signals.

[0152] Finally, it should be noted that the above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for overcurrent protection of a distribution line, characterized in that: Applied to a line protection device, the line protection device is used to monitor the line status of a multi-phase distribution line, the method comprises: Acquire a plurality of line voltages and a plurality of line currents, wherein the plurality of line voltages and the plurality of line currents correspond to each other one by one; Determine a variable impedance according to a preset unit impedance value, wherein the variable impedance amplitude is positively correlated with the preset unit impedance value, the variable impedance amplitude is an amplitude corresponding to the variable impedance, and the preset unit impedance value is positively correlated with the line length of the power distribution line; Determine the operating voltage according to the variable impedance, the first line current and the first line voltage, wherein the first line current is any one of the multiple line currents that is greater than or equal to a preset overcurrent threshold, and the first line voltage is a line voltage of the multiple line voltages corresponding to the first line current; Determining a phase angle according to the operating voltage and the polarization voltage; If the phase comparison angle is within the preset angle range, a target action delay is determined according to the variable impedance and the preset action delay, and the target action delay is negatively correlated with the variable impedance amplitude.

2. The overcurrent protection method for distribution lines according to claim 1, characterized in that: The step of determining the variable impedance according to the preset unit impedance value includes: Get line impedance angle; The variable impedance is determined according to the line impedance angle, the preset unit impedance value and the first time period. The variable impedance angle corresponding to the variable impedance is the same as the line impedance angle. The variable impedance amplitude is positively correlated with the first time period. The starting time of the first time period is the first time. The first time is the time when the line protection device detects the start signal. The end time of the first time period is the current time.

3. The overcurrent protection method for distribution lines according to claim 2, characterized in that: The determining the variable impedance according to the line impedance angle, the preset unit impedance value and the first time period includes: Determine the quotient of the first time period divided by the sampling period as the amplitude coefficient; Determine the product of the amplitude coefficient and the preset unit impedance value as the variable impedance amplitude; The variable impedance is determined according to the variable impedance amplitude and the line impedance angle.

4. The overcurrent protection method for distribution lines according to claim 2, characterized in that: Determining a target action delay according to the variable impedance and the preset action delay includes: Obtaining a reference impedance; determining a ratio of the variable impedance amplitude to the reference impedance; determining an acceleration time of the line protection device according to the ratio and the preset action delay; Determine the target action delay according to the acceleration time and the preset action delay; If the difference between the preset action delay and the acceleration time is greater than or equal to the shortest action delay, the target action delay is determined to be the difference between the preset action delay and the acceleration time; If the difference between the preset action delay and the acceleration time is smaller than the shortest action delay, the target action delay is determined to be the shortest action delay.

5. The overcurrent protection method for distribution lines according to claim 1, characterized in that: The step of determining the operating voltage according to the variable impedance, the first line current and the first line voltage includes: The difference between the first line voltage and the product of the variable impedance and the first line current is determined as the operating voltage.

6. The overcurrent protection method for distribution lines according to claim 1, characterized in that: Determining the phase angle according to the working voltage and the polarization voltage includes: Get the rated voltage amplitude; Determining a minimum voltage amplitude according to the rated voltage amplitude, wherein the minimum voltage amplitude is proportional to the rated voltage amplitude; If the multiple line voltages are all less than or equal to the minimum voltage amplitude, the polarization voltage is determined according to multiple reference line voltages, where the multiple reference line voltages are line voltages collected by the line protection device at a second moment, where the second moment is a moment before the first moment when the line protection device detects a start signal and is separated from the first moment by k sampling periods, where k is an integer greater than 0 and less than 5; If there is a second line voltage greater than the minimum voltage amplitude among the multiple line voltages, determining the positive sequence voltage corresponding to the first line voltage as the polarization voltage; The angle of the ratio of the working voltage to the polarization voltage is determined as the phase angle.

7. The overcurrent protection method for distribution lines according to claim 6, characterized in that: The multiple reference line voltages correspond to the multiple line voltages one by one, and determining the polarization voltage according to the multiple reference line voltages includes: Acquire a sampling sequence number corresponding to the first line voltage, where the sampling sequence number is used to represent the number of times the line protection device samples the line voltage after the first moment; Get the number of cycle sampling points; Determine the ratio of 360° to the number of cycle sampling points as the sampling angle step; Determine the product of the sampling angle step and the sampling sequence number and the sum of the first reference line voltage angle as the polarization voltage angle corresponding to the polarization voltage, the first reference line voltage is one of the multiple reference line voltages corresponding to the first line voltage, and the first reference line voltage angle is the angle corresponding to the first reference line voltage; The polarization voltage is determined according to the polarization voltage angle.

8. The overcurrent protection method for distribution lines according to any one of claims 1 to 7, characterized in that: After determining the target action delay according to the variable impedance and the preset action delay, the method further includes: Based on a preset sampling frequency, a plurality of groups of second line currents are continuously acquired within a second time period, each group of the second line currents includes a plurality of second line currents, the plurality of second line currents correspond to the plurality of line currents one by one, the start time of the second time period is the current time, and the time interval of the second time period is the target action delay; If multiple target second line currents corresponding to multiple groups of second line currents are all greater than or equal to the preset overcurrent threshold, disconnection instructions are sent to multiple circuit breakers respectively, the target second line current is the line current corresponding to the first line current among the multiple second line currents, the multiple circuit breakers correspond one-to-one to the multi-phase distribution lines, the multiple circuit breakers are used to change the line state of the multi-phase distribution lines, and the disconnection instruction is used to instruct the circuit breakers to change the line state to a disconnected state.

9. An electronic device, characterized in that: It comprises a processor and a memory, wherein the processor is used to execute a computer program stored in the memory to implement the distribution line overcurrent protection method as described in any one of claims 1 to 8.

10. A computer-readable storage medium storing a computer program, characterized in that: When the computer program is executed by a processor, the method for overcurrent protection of a power distribution line as described in any one of claims 1 to 8 is implemented.

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