Distribution line distance 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 distance protection method, electronic equipment and a computer storage medium. The method comprises the following steps: acquiring first measurement impedance corresponding to a fault phase, a preset unit inductive reactance value and preset stage difference time; according to the preset unit inductive reactance value, the preset stage difference time and the first time interval, the target impedance rate is determined, the target impedance rate is in positive correlation with the preset unit inductive reactance value, and the target impedance rate is in negative correlation with the preset stage difference time. And determining a target inductive reactance value and a target impedance value according to the target impedance rate. And if the absolute value of the real part impedance of the first measurement impedance is smaller than the target impedance value and the absolute value of the imaginary part inductive reactance of the first measurement impedance is smaller than the target inductive reactance value, indicating the circuit breaker to change the line state into a disconnected state. According to the invention, when the distribution line has a fault, the line protection device closest to the fault point is enabled to act, and the minimum isolation of the fault area is realized.

Description

Technical Field

[0001] The present application relates to the technical field of relay protection for power systems, and particularly to a distance protection method for distribution lines, an electronic device, and a computer storage medium. Background Art

[0002] In a power system, distance protection is a backup protection method widely used in the high-voltage power grid of the power system. The line protection device can determine the distance between the line protection device and the fault point by calculating the difference between the measured impedance and the preset impedance when a fault occurs.

[0003] However, the setting of the preset impedance requires accurate measurement of line parameters. Since there are many types and a large number of existing distribution lines, it is difficult to accurately measure the line parameters of each section between multiple line protection devices, and the distance protection method for distribution lines has low feasibility.

[0004] In addition, when the lengths of the upper and lower adjacent lines differ greatly, the distance protection of the adjacent upper and lower line protection devices is prone to lose selectivity, which easily leads to misoperation or refusal to operate of the line protection device across levels when a line fault occurs. The distance protection method for distribution lines is difficult to implement in application scenarios where the lengths of the upper and lower adjacent lines differ greatly. Summary of the Invention

[0005] The present application provides a distance protection method for distribution lines, an electronic device, and a computer-readable storage medium. When a fault occurs in a distribution line, it can make the line protection device closest to the fault point operate, without the need to accurately measure the line parameters of the protected line, and is not affected by the line length. It can improve the reliability of the operation of the line protection device, achieve the minimum isolation of the fault area, and improve the reliability of the operation of the distribution line.

[0006] In a first aspect, the present application provides a distance protection method for distribution lines, which is applied to a first line protection device. The first line protection device is used to monitor the line state of a first line segment. The method includes: obtaining a first measured impedance corresponding to a fault phase, and obtaining a preset unit inductive reactance value and a preset differential time. According to the preset unit inductive reactance value, the preset differential time, and a first time interval, a target impedance rate is determined. The target impedance rate is positively correlated with the preset unit inductive reactance value, and the target impedance rate is negatively correlated with the preset differential time. The start time of the first time interval is the fault time, and the end time of the first time interval is the current time. According to the target impedance rate, a target inductive reactance value and a target impedance value are determined. Both the target inductive reactance value and the target impedance value are positively correlated with the target impedance rate. If the absolute value of the real part impedance of the first measured impedance is less than the target impedance value, and the absolute value of the imaginary part inductive reactance of the first measured impedance is less than the target inductive reactance value, a disconnection instruction is sent to the circuit breaker. The disconnection instruction is used to instruct the circuit breaker to change the line state to a disconnected state.

[0007] In some embodiments, before the step of sending a disconnection instruction to the circuit breaker, it further includes: based on a preset sampling frequency, continuously obtaining a plurality of second measured impedances corresponding to the fault phase within a preset time period, where the preset time period is a time period after the current moment and spaced from the current moment by a second time interval.

[0008] In some embodiments, sending a disconnection instruction to the circuit breaker includes: if the absolute values of the real part impedances of the plurality of second measured impedances are all less than the target impedance value, and the absolute values of the imaginary part inductive reactances of the plurality of second measured impedances are all less than the target inductive reactance value, then sending a disconnection instruction to the circuit breaker.

[0009] In some embodiments, obtaining a first measured impedance corresponding to the fault phase includes: obtaining a plurality of first line currents at a first moment, where the first moment is any moment before the first line protection device starts the distance protection process. If there is a line current greater than or equal to a preset overcurrent setting value among the plurality of first line currents, record the first moment as the fault moment, and determine the phase corresponding to the line current with the largest current amplitude among the plurality of first line currents as the fault phase. Obtain a second line voltage and a second line current corresponding to the fault phase at a second moment. Determine the ratio of the second line voltage to the second line current as the first measured impedance.

[0010] In some embodiments, the line length corresponding to the first line segment is the first line length, the lower-level line protection device adjacent to the first line protection device is the second line protection device, and the second line protection device is used to monitor the line state of the second line segment, and the line length corresponding to the second line segment is the second line length. Determining the target impedance rate according to a preset unit inductive reactance value, a preset grading time, and a first time interval includes: if the first time interval is less than or equal to the preset grading time, determine the target impedance rate as the first ratio of the product of the preset unit inductive reactance value and the first line length to the preset grading time. If the first time interval is greater than the preset grading time and less than or equal to twice the preset grading time, determine the target impedance rate as the second ratio of the product of the preset unit inductive reactance value and the second line length to the preset grading time. If the first time interval is greater than twice the preset grading time, determine the target impedance rate as the smaller value of the first ratio and the second ratio.

[0011] In some embodiments, determining a target inductive reactance value and a target impedance value according to a target impedance rate includes: If a first time interval is less than or equal to a preset differential time, determining the target inductive reactance value as the product of the target impedance rate and the first time interval. If the first time interval is greater than the preset differential time and less than or equal to twice the preset differential time, determining the target inductive reactance value as the sum of a first summand and a second summand, where the first summand is the product of a preset unit inductive reactance value and a first line length, and the second summand is the product of the difference between the first time interval and the preset differential time and the target impedance rate. If the first time interval is greater than twice the preset differential time, determining the target inductive reactance value as the sum of a third summand and a fourth summand, where the third summand is the product of the sum of the first line length and a second line length and the preset unit inductive reactance value, and the fourth summand is the product of the difference between the first time interval and twice the preset differential time and the target impedance rate. Determining the target impedance value according to the target impedance rate and a preset ratio coefficient, where the target impedance value is positively correlated with both the target inductive reactance value and the preset ratio coefficient.

[0012] In some embodiments, if there is no second line protection device, assign the value of the first line length to the second line length.

[0013] In some embodiments, the target impedance value is the product of the target inductive reactance value and the preset ratio coefficient.

[0014] In a second aspect, the present application provides a distribution line distance protection device, which can be a first line protection device for monitoring the line state of a first line segment. The device includes: an acquisition module and a processing module; The acquisition module is used to acquire a first measured impedance corresponding to a fault phase, and to acquire a preset unit inductive reactance value and a preset differential time.

[0015] The processing module is used to determine a target impedance rate according to the preset unit inductive reactance value, the preset differential time, and a first time interval. The target impedance rate is positively correlated with the preset unit inductive reactance value and negatively correlated with the preset differential time. The start time of the first time interval is the fault time, and the end time of the first time interval is the current time.

[0016] The processing module is further used to determine a target inductive reactance value and a target impedance value according to the target impedance rate. Both the target inductive reactance value and the target impedance value are positively correlated with the target impedance rate. If the absolute value of the real part impedance of the first measured impedance is less than the target impedance value, and the absolute value of the imaginary part inductive reactance of the first measured impedance is less than the target inductive reactance value, send a disconnection instruction to the circuit breaker, and the disconnection instruction is used to instruct the circuit breaker to change the line state to the disconnected state.

[0017] In a third aspect, the present application provides a chip for executing the method in any one of the above first aspects.

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

[0019] In a fifth aspect, the present application provides a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the method in any one of the above first aspects.

[0020] In a sixth aspect, the present application provides a computer program product storing a computer program, which, when executed by a processor, implements the method in any one of the above first aspects.

[0021] In the technical solution provided by the present application, the first line protection device can, after obtaining the first measured impedance corresponding to the fault phase, as well as a preset unit inductive reactance value and a preset differential time, determine a target impedance rate according to the preset unit inductive reactance value, the preset differential time, and a first time interval. The target impedance rate is positively correlated with the preset unit inductive reactance value, and the target impedance rate is negatively correlated with the preset differential time. The start time of the first time interval is the fault time, and the end time of the first time interval is the current time. Then, according to the target impedance rate, a target inductive reactance value and a target impedance value are determined. Both the target inductive reactance value and the target impedance value are positively correlated with the target impedance rate. If the absolute value of the real part impedance of the first measured impedance is less than the target impedance value, and the absolute value of the imaginary part inductive reactance of the first measured impedance is less than the target inductive reactance value, a disconnection instruction is sent to the circuit breaker. The disconnection instruction is used to instruct the circuit breaker to change the line state to the disconnected state. The technical solution provided by the present application can, when a fault occurs in a distribution line, determine the specific area where the fault point is located, cause the line protection device closest to the fault point to act, without accurately measuring the line parameters of the protected line, and is not affected by the line length, can improve the reliability of the line protection device action, achieve the minimum isolation of the fault area, and improve the reliability of the distribution line operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0023] Figure 1 is a schematic diagram of a system architecture provided by an embodiment of the present application; Figure 2 It is a schematic diagram of a distance protection startup process provided by an embodiment of the present application; Figure 3 It is a schematic diagram of a distance protection process of a distribution line distance protection method provided by an embodiment of the present application; Figure 4 It is a schematic diagram of a protection action area provided by an embodiment of the present application; Figure 5 It is a schematic diagram of a distribution line distance protection device provided by an embodiment of the present application; Figure 6 It is a schematic diagram of an electronic device provided by an embodiment of the present application. Detailed implementation manners

[0024] In the following description, for the purpose of illustration rather than limitation, specific details such as specific system architectures, technologies, etc. are put forward to thoroughly understand the embodiments of the present application. However, those skilled in the art should clearly understand that the present application can 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 avoid unnecessary details from interfering with the description of the present application.

[0025] It should be understood that when used in the specification of the present application and the appended claims, the term "comprising" indicates the presence of the described features, wholes, steps, operations, elements, and / or components, but does not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0026] It should also be understood that the term "and / or" as used in the specification of the present application and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0027] As used in the specification of the present application and the appended claims, the term "if" can be interpreted as "when" or "once" or "in response to determining" or "in response to detecting" according to the context. Similarly, the phrase "if determined" or "if detecting [the described condition or event]" can be interpreted as meaning "once determined" or "in response to determining" or "once detecting [the described condition or event]" or "in response to detecting [the described condition or event]" according to the context.

[0028] In addition, in the description of the specification of the present application and the appended claims, the terms "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0029] References to "one embodiment" or "some embodiments" etc. described in the specification of this application mean that a particular feature, structure, or characteristic described in connection with that embodiment is included in one or more embodiments of this application. Thus, statements such as "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily all refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized. The terms "comprising", "including", "having" and their variants all mean "including but not limited to", unless otherwise specifically emphasized.

[0030] Stepped overcurrent protection is a key method for achieving selective protection in a distribution network. It can ensure that only the protection of the nearest fault point operates when a fault occurs and avoid out-of-sequence tripping through the dual coordination of the action time and current setting values set at different levels. It includes: time step and current step.

[0031] Time step: From the load side to the power source side, the action time increases step by step. Specifically, the action delay set on the line protection device close to the load is the shortest, the action delay set on the line protection device close to the power source is the longest, and the action delays set on the intermediate line protection devices increase in turn.

[0032] For example, the action times set on the line protection devices from the load side to the power source side form an arithmetic sequence between 0.1 s and 0.5 s.

[0033] Current step: The current setting value set on the upper-level line protection device needs to be greater than the current setting value set on the lower-level protection device, that is, from the power source side to the load side, the current setting values decrease step by step. Specifically, the current setting value set on the line protection device close to the power source is the largest, the overcurrent threshold set on the line protection device close to the load is the smallest, and the action delays set on the intermediate line protection devices decrease in turn.

[0034] Exemplarily, the current setting value set on the upper-level line protection device can be 1.2 to 1.5 times the current setting value set on the adjacent lower-level protection device.

[0035] For example, Figure 1 is a schematic diagram of a system architecture provided by an embodiment of this application. As Figure 1As shown in the figure, the grid side is the power supply side. A line protection device 1, a line protection device 2, and a line protection device 3 are sequentially installed from the grid side to the load side. The line protection device 1 is the adjacent upper-level line protection device of the line protection device 2, and the line protection device 2 is the adjacent upper-level line protection device of the line protection device 3. The current setting value corresponding to the line protection device 1 is the largest, and it is 1.2 times the current setting value corresponding to the line protection device 2. The current setting value corresponding to the line protection device 2 is 1.2 times the current setting value corresponding to the line protection device 3.

[0036] The line protection device can achieve current stepped coordination for overcurrent protection through the collected fault current. However, since the distribution line is usually short, when a fault occurs at different positions of the distribution line, the difference in the fault current flowing through the distribution line is usually small, resulting in difficulty in achieving current stepped coordination, and the line protection device cannot accurately isolate the fault area.

[0037] Distance protection is a backup protection method widely used in the high-voltage power grid of the power system. The line protection device can determine the distance between the line protection device and the fault point by calculating the difference between the measured impedance and the preset impedance when a fault occurs.

[0038] However, the setting of the preset impedance requires accurate measurement of the line parameters. Due to the large variety and quantity of existing distribution line types, it is difficult to accurately measure the line parameters of each section between multiple line protection devices, and the distance protection method for distribution lines has low feasibility.

[0039] In addition, when the lengths of the upper and lower level lines differ greatly, the distance protection of adjacent upper and lower level line protection devices is prone to losing selectivity, which easily leads to misoperation or refusal to operate of the line protection device when a line fault occurs. The distance protection method for distribution lines is difficult to implement in application scenarios where the lengths of the upper and lower level lines differ greatly.

[0040] In view of this, the embodiments of the present application provide a distance protection method for distribution lines, which can determine the specific area where the fault point is located when a fault occurs in the distribution line, cause the line protection device closest to the fault point to operate, without the need to accurately measure the line parameters of the protected line, and is not affected by the line length, can improve the reliability of the operation of the line protection device, achieve the minimum isolation of the fault area, and improve the reliability of the operation of the distribution line.

[0041] The technical solutions of the embodiments of the present application will be described below with reference to the examples in the accompanying drawings.

[0042] Figure 2 It is a schematic diagram of a distance protection startup process provided by the embodiments of the present application. As Figure 1 shown, before starting the distance protection method for the distribution line, the line protection device can also perform the following steps: Step S201: Obtain a plurality of first phase currents corresponding to a polyphase distribution line at a first moment. The plurality of first phase currents correspond one-to-one to the polyphase distribution line, and the first moment is any moment before the first line protection device starts the distance protection process.

[0043] Before starting the distance protection method for the distribution line, the line protection device can obtain in real time a plurality of phase currents (first phase currents) corresponding to the polyphase distribution line, and determine whether to start the distance protection process for the distribution line according to the plurality of first phase currents. The polyphase distribution line can be the three-phase lines in a three-phase system, namely: phase A line, phase B line, and phase C line, and the first phase currents can be respectively represented as: I A 、I B and I C .

[0044] The line protection device can be any line protection device in the power system.

[0045] For example, referring to Figure 1 continuously, the line protection device can be line protection device 1, line protection device 2, or line protection device 3.

[0046] Step S202: Determine a plurality of first line currents according to the plurality of first phase currents. The number of the plurality of first line currents is the same as that of the plurality of first phase currents.

[0047] The line protection device can obtain in real time a plurality of phase currents (i.e., a plurality of first phase currents) corresponding to the polyphase distribution line, and calculate in real time a plurality of line currents (i.e., first line currents) according to the plurality of phase currents.

[0048] Exemplarily, the plurality of phase currents can be respectively: the current flowing through the phase A line, the current flowing through the phase B line, and the current flowing through the phase C line, which are respectively represented as I A 、I B and I C , and the plurality of line currents can be respectively: the difference between the current in the wire corresponding to the phase A line and the current in the wire corresponding to the phase B line, the difference between the current in the wire corresponding to the phase B line and the current in the wire corresponding to the phase C line, the difference between the current in the wire corresponding to the phase C line and the current in the wire corresponding to the phase A line, which are respectively represented as: I AB 、I BC and I CA . Among them, I AB =I A -I B ; I BC =I B -I C ; I CA =I C -I A .

[0049] Step S203: Determine whether there is a line current greater than or equal to a preset overcurrent setting value among multiple first-line currents.

[0050] The line protection device may be preset with a preset overcurrent setting value I set , when the distribution line is operating normally, the line current of the distribution line generally does not exceed the rated line current of the protection device. When the line current exceeds the rated line current, the probability that the distribution line is in a short-circuit fault state is relatively high. Therefore, the preset overcurrent setting value can be a value greater than the rated line current. Exemplarily, the preset overcurrent setting value can be 1.2 times the rated line current. The present application does not limit the specific multiple relationship between the preset overcurrent setting value and the rated line current.

[0051] In some embodiments, the line protection device may also set the preset overcurrent setting value according to the estimated current magnitude during a line fault.

[0052] If there is a line current greater than or equal to the preset overcurrent setting value among multiple first-line currents, the line protection device executes step S204. If there is no line current greater than or equal to the preset overcurrent setting value among multiple first-line currents, the line protection device does not need to execute subsequent steps until there is a line current greater than or equal to the preset overcurrent setting value among the obtained multiple line currents, and then starts the distance protection process for the distribution line.

[0053] Step S204: If there is a line current greater than or equal to the preset overcurrent setting value among multiple first-line currents, record the first moment as the fault moment, and determine the phase corresponding to the line current with the largest current amplitude among multiple first-line currents as the fault phase.

[0054] Exemplarily, if among I AB 、I BC and I CA , the current amplitude corresponding to I AB is the largest, the line protection device can determine that the AB phase is the fault phase; if the current amplitude corresponding to I BC is the largest, the line protection device can determine that the BC phase is the fault phase; if the current amplitude corresponding to I CA is the largest, the line protection device can determine that the CA phase is the fault phase.

[0055] After the line protection device determines that there is a fault in the distribution line and determines the fault phase, it can determine whether to perform a distance protection action. Figure 3 This is a schematic diagram of a distance protection process of a distance protection method for a distribution line provided by an embodiment of the present application. As Figure 3 shown, the process for the line protection device to execute distance protection may include the following steps: Step S301: Obtain the first measured impedance corresponding to the faulty phase, and obtain the preset unit reactance value and the preset grading time.

[0056] The method for determining the faulty phase can refer to the method for determining the faulty phase in the corresponding embodiment above. This application will not elaborate here. Figure 2 The corresponding embodiment of the method for determining the faulty phase in the corresponding embodiment above. This application will not elaborate here.

[0057] The line protection device can be the first line protection device, and the first line protection device is used to monitor the line state of the first line segment.

[0058] For example, continue to refer to Figure 1 , if the first line protection device is line protection device 1, then the first line segment is distribution line 1; if the first line protection device is line protection device 2, then the first line segment is distribution line 2; if the first line protection device is line protection device 3, then the first line segment is distribution line 3.

[0059] The line protection device can determine the first measured impedance according to the second line voltage and the second line current corresponding to the faulty phase obtained at the second moment. Specifically, the first measured impedance can be the ratio of the second line voltage to the second line current.

[0060] That is: ; Among them, represents the faulty phase. When the faulty phase is the AB phase, is AB; when the faulty phase is the BC phase, is BC; when the faulty phase is the CA phase, is CA. represents the second line voltage, represents the second line current.

[0061] The second moment can be any moment (the first moment) after the fault moment, or it can be the fault moment (the first moment). It should be understood that before starting the distance protection process, if the line protection device detects a line fault (there is a line current greater than or equal to the preset overcurrent setting value among multiple first line currents), it will start the distance protection process for the distribution line and execute step S301.

[0062] The preset unit reactance value X1 can be the estimated reactance value corresponding to the preset unit line length, and the preset unit reactance value X1 can be an empirical value. Exemplarily, the value range of the preset unit reactance value X1 can be 0.3~0.6Ω / km. For example, X1 = 0.3Ω / km. This application does not limit the specific value of the preset unit reactance value X1.

[0063] The preset grading time T setIt can be the difference between the action delays set on two adjacent line protection devices. For example, if the action times set on the line protection devices from the load side to the power source side are 0.1s, 0.2s, 0.3s, 0.4s, and 0.5s respectively, then the preset step time T set is 0.1s.

[0064] Step S302: Determine the target impedance rate according to the preset unit reactance value, the preset step time, and the first time interval. The target impedance rate is positively correlated with the preset unit reactance value and negatively correlated with the preset step time. The start time of the first time interval is the fault time, and the end time of the first time interval is the current time.

[0065] In the embodiment of the present application, the line protection device that executes the line distance protection method may be the first line protection device. The first line protection device is any line protection device in the distribution line, and the first line protection device is used to monitor the line state of the first line segment. The line length corresponding to the first line segment is the first line length L1. The subordinate line protection device adjacent to the first line protection device is the second line protection device, and the second line protection device is used to monitor the line state of the second line segment. The line length corresponding to the second line segment is the second line length L2.

[0066] When there is a subordinate line protection device adjacent to the first line protection device, the second line length L2 is the line length of the second line segment monitored by the second line protection device. If there is no second line protection device, the first line protection device may assign the value of the first line length L1 to the second line length L2.

[0067] For example, continuing to refer to Figure 1 , if the first line protection device is line protection device 1, then the first line length is 2 km and the second line length is 3 km; if the first line protection device is line protection device 2, then the first line length is 3 km and the second line length is 4 km; if the first line protection device is line protection device 3, since there is no subordinate line protection device adjacent to line protection device 3, line protection device 3 may assign the first line length to the second line length, and the second line length is also 4 km.

[0068] In the embodiment of the present application, the current time may be the second time T2. If the fault time is T1, then the first time interval t = T2 - T1. The first line protection device determines the target impedance rate according to the preset unit reactance value X1, the preset step time T set and the first time interval t. The method may include: if the first time interval t is less than or equal to the preset step time T set, the first line protection device determines that the target impedance rate is the product of the preset unit inductive reactance value X1 and the first line length L1 divided by the preset grading time T set The first ratio k1. If the first time interval t is greater than the preset grading time T set , and less than or equal to twice the preset grading time 2T set , the first line protection device determines that the target impedance rate is the product of the preset unit inductive reactance value X1 and the second line length L2 divided by the preset grading time T set The second ratio k2. If the first time interval is greater than twice the preset grading time 2T set , the first line protection device determines that the target impedance rate is the smaller value k3 of the first ratio k1 and the second ratio k2.

[0069] That is, when the first time interval t is less than or equal to the preset grading time T set , and greater than or equal to 0, the calculation formula for the target impedance rate is: Formula 1; If the first time interval t is greater than the preset grading time T set , and less than or equal to twice the preset grading time, the calculation formula for the target impedance rate is: Formula 2; If the first time interval is greater than twice the preset grading time, the calculation formula for the target impedance rate is: Formula 3.

[0070] Step S303: Determine the target inductive reactance value and the target impedance value according to the target impedance rate, and both the target inductive reactance value and the target impedance value are positively correlated with the target impedance rate.

[0071] In the embodiment of the present application, the method for the first line protection device to determine the target inductive reactance value X set may include the following: If the first time interval t is less than or equal to the preset grading time T set , then determine that the target inductive reactance value X set is the product of the target impedance rate k1 and the first time interval t. If the first time interval t is greater than the preset grading time T set , and less than or equal to twice the preset grading time 2T set , then determine that the target inductive reactance value X set is the sum of the first summand and the second summand. The first summand is the product of the preset unit inductive reactance value X1 and the first line length L1, and the second summand is the product of the difference between the first time interval t minus the preset grading time T set and the target impedance rate k2. If the first time interval t is greater than twice the preset grading time 2Tset , the target inductive reactance value X is determined set is the sum of the third summation term and the fourth summation term. The third summation term is the product of the sum of the first line length L1 and the second line length L2 and the preset unit inductive reactance value X1. The fourth summation term is the product of the difference between the first time interval t and twice the preset step time 2T set and the target impedance rate k3.

[0072] That is, when the first time interval t is less than or equal to the preset step time T set , and greater than or equal to 0, the first line protection device can calculate the target impedance rate k1 through the above formula 1, and calculate the target inductive reactance value X through the target impedance rate k1 set , the target inductive reactance value X set The calculation formula is: Formula 4; If the first time interval t is greater than the preset step time T set , and less than or equal to twice the preset step time 2T set , the first line protection device can calculate the target impedance rate k2 through the above formula 2, and calculate the target inductive reactance value X through the target impedance rate k2 set , the target inductive reactance value X set The calculation formula is: Formula 5; If the first time interval t is greater than twice the preset step time 2T set , the first line protection device can calculate the target impedance rate k3 through the above formula 1, formula 2 and formula 3, and calculate the target inductive reactance value X through the target impedance rate k3 set , the target inductive reactance value X set The calculation formula is: Formula 6; The first line protection device can determine the target impedance value according to the target impedance rate and the preset ratio coefficient. The target impedance value is positively correlated with the target inductive reactance value and the preset ratio coefficient. Specifically, the target impedance value R set can be the product of the target inductive reactance value X set and the preset ratio coefficient kr.

[0073] That is, the target impedance value R set = kr×X set Formula 7; The preset ratio coefficient kr can be the target impedance value R setThe ratio coefficient, a preset ratio coefficient kr greater than 1. The preset ratio coefficient kr can be used to increase the ability of distance protection to withstand short - circuit faults with transition resistance. It should be understood that the larger the preset ratio coefficient kr, the stronger the ability to withstand short - circuit faults with transition resistance. Exemplarily, the preset ratio coefficient kr can be 10 or other values, which are not limited in this application.

[0074] Step S304: If the absolute value of the real - part impedance of the first measured impedance is less than the target impedance value, and the absolute value of the imaginary - part reactance of the first measured impedance is less than the target reactance value, then send a disconnection instruction to the circuit breaker. The disconnection instruction is used to instruct the circuit breaker to change the line state to the disconnected state.

[0075] The first line protection device can determine whether to perform the action of isolating the fault area according to the first measured impedance. Specifically, the first line protection device can judge whether the first measured impedance falls within the protection area composed of the target reactance value X set and the target impedance value R set by the real - part impedance Rm and the imaginary - part reactance Xm of the first measured impedance. If the first measured impedance satisfies both the instantaneous - action condition 1 and the instantaneous - action condition 2, the first line protection device can then determine whether the first measured impedance falls within the protection area composed of the target reactance value X set and the target impedance value R set The instantaneous - action condition 1 and the instantaneous - action condition 2 are respectively: Instantaneous - action condition 1: The absolute value |Rm| of the real - part impedance of the first measured impedance is less than the target impedance value R set , that is, |Rm| < R set .

[0076] Instantaneous - action condition 2: The absolute value |Xm| of the imaginary - part reactance of the first measured impedance is less than the target reactance value X set , that is, |Xm| < X set .

[0077] Figure 4 This is a schematic diagram of a protection - action area of a distribution - line distance - protection method provided by an embodiment of this application. The horizontal (real - part impedance direction) range of the protection - action area is the range between - R set and R set , and the vertical (imaginary - part reactance direction) range of the protection - action area is the range between... If the first measured impedance satisfies both the instantaneous - action condition 1 and the instantaneous - action condition 2, it indicates that the first measured impedance falls within the dotted - line area shown in the figure, and the first line protection device can set the distribution - line distance - protection action flag to 1; if the first measured impedance does not satisfy both the instantaneous - action condition 1 and the instantaneous - action condition 2, it indicates that the first measured impedance does not fall within the dotted - line area shown in the figure, and the first line protection device can set the distribution - line distance - protection action flag to 0.

[0078] In the embodiment of the present application, when the action flag of the distance protection of the distribution line is 1, the first line protection device can send a disconnection command to the circuit breakers corresponding to the three-phase lines, and the first line protection device can isolate the fault area.

[0079] Continue to refer to Figure 1 , if an interphase short-circuit fault occurs at point F1, the line protection device 3 is the closest to the fault point F1, and the line protection device 1 is the farthest from the fault point F1. Then the first measured impedance measured by the line protection device 1 is the largest, and the first measured impedance measured by the line protection device 3 is the smallest. According to Formulas 1 to 7, as the first time interval gradually increases, the target inductive reactance values X set and the target impedance values R set both gradually increase. That is, the protection area composed of the target inductive reactance value X set and the target impedance value R set gradually increases. Then the line protection device 3 closest to the fault point F1 first satisfies the instantaneous action condition 1 and the instantaneous action condition 2. Therefore, the line protection device 3 closest to the fault point F1 first operates, sends a disconnection command to the circuit breakers corresponding to the three-phase lines to isolate the fault area, and can avoid the overstepping misoperation of the line protection device or the refusal of the line protection device to operate, realizing accurate isolation of the fault area.

[0080] When the action flag of the distance protection of the distribution line is 0, the first line protection device does not operate, which can avoid the overstepping misoperation of the line protection device.

[0081] In some embodiments, to avoid the misoperation of the line protection device caused by a single misjudgment, the first line protection device can also set a preset time period Td. If the action flag of the distance protection of the distribution line continues to be 1 within the preset time period Td, the first line protection device sends a disconnection command to the circuit breakers corresponding to the three-phase lines to isolate the fault area.

[0082] Specifically, when the first measured impedance simultaneously satisfies the instantaneous action condition 1 and the instantaneous action condition 2, the first line protection device can keep the current target inductive reactance value X set and the target impedance value R set unchanged, that is, keep the range of the protection area unchanged. Based on the preset sampling frequency, a plurality of second measured impedances corresponding to the fault phase are continuously obtained within the preset time period Td. The preset time period Td is a time period after the current moment and spaced from the current moment by a second time interval. Exemplarily, the duration corresponding to the preset time period Td can be 5 s, or other time values, which are not limited in this application.

[0083] If the operating flag of the distance protection of the distribution line remains 1 within a preset time period, that is, the absolute values of the real part impedances of multiple second measured impedances are all less than the target impedance value, and the absolute values of the imaginary part inductive reactances of multiple second measured impedances are all less than the target inductive reactance value, the first line protection device can send a disconnection instruction to the circuit breaker.

[0084] By setting the preset time period in this application, the accuracy and reliability of the operation of the first line protection device can be improved.

[0085] In the technical solution provided by the embodiment of this application, the first line protection device can, after obtaining the first measured impedance corresponding to the fault phase, as well as the preset unit inductive reactance value and the preset differential time, determine the target impedance rate according to the preset unit inductive reactance value, the preset differential time, and the first time interval. The target impedance rate is positively correlated with the preset unit inductive reactance value, and the target impedance rate is negatively correlated with the preset differential time. The start time of the first time interval is the fault time, and the end time of the first time interval is the current time. Then, according to the target impedance rate, the target inductive reactance value and the target impedance value are determined. Both the target inductive reactance value and the target impedance value are positively correlated with the target impedance rate. If the absolute value of the real part impedance of the first measured impedance is less than the target impedance value, and the absolute value of the imaginary part inductive reactance of the first measured impedance is less than the target inductive reactance value, a disconnection instruction is sent to the circuit breaker. The disconnection instruction is used to instruct the circuit breaker to change the line state to the disconnected state. The technical solution provided by the embodiment of this application can, when a fault occurs in the distribution line, determine the specific area where the fault point is located, cause the line protection device closest to the fault point to operate, without accurately measuring the line parameters of the protected line, and is not affected by the line length, can improve the reliability of the operation of the line protection device, realize the minimum isolation of the fault area, and improve the reliability of the operation of the distribution line.

[0086] It should be understood that, on the premise of no logical conflict, the above-mentioned various application embodiments can be combined and implemented with each other to meet the actual application requirements. The specific embodiments or implementation schemes obtained after these combinations still fall within the protection scope of this application.

[0087] Corresponding to the distribution line distance protection method in the above embodiment, the embodiment of this application provides a distribution line distance protection device 50. The distribution line distance protection device 50 can be the first line protection device, and the first line protection device is used to monitor the line state of the first line segment. The distribution line distance 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 distance protection method in the above embodiment.

[0088] Figure 5 The structural schematic diagram of a distribution line distance protection device provided by the embodiment of this application is shown. For the sake of convenience of description, only the parts related to the embodiment of this application are shown.

[0089] Reference Figure 5 The distribution line distance protection device 50 includes an acquisition module 510 and a determination module 520 .

[0090] The acquisition module 510 is configured to acquire the first measured impedance corresponding to each fault phase, and to acquire a preset unit inductive reactance value and a preset step time.

[0091] Determination module 520 is used to determine the target impedance rate based on the preset unit inductance value, the preset step difference time and the first time interval. The target impedance rate is positively correlated with the preset unit inductance value, and the target impedance rate is negatively correlated with the preset step difference time. The start time of the first time interval is the fault time, and the end time of the first time interval is the current time.

[0092] Determining module 520 is further configured to determine a target inductive reactance value and a target impedance value based on the target impedance rate, where both the target inductive reactance value and the target impedance value are positively correlated with the target impedance rate. If the absolute value of the real impedance of the first measured impedance is less than the target impedance value, and the absolute value of the imaginary inductive reactance of the first measured impedance is less than the target inductive reactance value, a disconnect instruction is sent to the circuit breaker. The disconnect instruction is configured to instruct the circuit breaker to change the line state to the disconnected state.

[0093] In some embodiments, the determination module 520 is specifically configured to: continuously obtain multiple second measured impedances corresponding to the fault phases within a preset time period based on a preset sampling frequency, where the preset time period is a time period after the current moment and separated from the current moment by a second time interval.

[0094] In some embodiments, the determination module 520 is specifically configured to send a disconnect instruction to the circuit breaker if the absolute values of the real impedances of the plurality of second measured impedances are all smaller than the target impedance value, and the absolute values of the imaginary inductive reactances of the plurality of second measured impedances are all smaller than the target inductive reactance value.

[0095] In some embodiments, the acquisition module 510 is specifically configured to: acquire multiple first line currents at a first moment, where the first moment is any moment before the first line protection device initiates the distance protection process. If a line current among the multiple first line currents is greater than or equal to a preset overcurrent setting, record the first moment as the fault moment, and determine the phase corresponding to the line current with the largest current amplitude among the multiple first line currents as the fault phase. At a second moment, acquire the second line voltage and second line current corresponding to the fault phase. Determine the ratio of the second line voltage to the second line current as the first measurement impedance.

[0096] In some embodiments, the line length corresponding to the first line segment is a first line length, the lower-level line protection device adjacent to the first line protection device is a second line protection device, the second line protection device is configured to monitor the line status of the second line segment, and the line length corresponding to the second line segment is a second line length. Determination module 520 is specifically configured to: if the first time interval is less than or equal to a preset step difference time, determine the target impedance rate as a first ratio of the product of a preset unit inductive reactance value and the first line length to the preset step difference time. If the first time interval is greater than the preset step difference time and less than or equal to twice the preset step difference time, determine the target impedance rate as a second ratio of the product of a preset unit inductive reactance value and the second line length to the preset step difference time. If the first time interval is greater than twice the preset step difference time, determine the target impedance rate as the smaller of the first ratio and the second ratio.

[0097] In some embodiments, the determination module 520 is specifically configured to: if the first time interval is less than or equal to a preset step difference time, determine the target inductive reactance value as the product of the target impedance rate and the first time interval. If the first time interval is greater than the preset step difference time and less than or equal to twice the preset step difference time, determine the target inductive reactance value as the sum of a first additive term and a second additive term, where the first additive term is the product of a preset unit inductive reactance value and the first line length, and the second additive term is the product of the difference between the first time interval and the preset step difference time and the target impedance rate. If the first time interval is greater than twice the preset step difference time, determine the target inductive reactance value as the sum of a third additive term and a fourth additive term, where the third additive term is the product of the sum of the first line length and the second line length and the preset unit inductive reactance value, and the fourth additive term is the product of the difference between the first time interval and twice the preset step difference time and the target impedance rate. The target impedance value is determined based on the target impedance rate and a preset ratio coefficient, where the target impedance value is positively correlated with both the target inductive reactance value and the preset ratio coefficient.

[0098] In some embodiments, if the second line protection device does not exist, the value of the first line length is assigned to the second line length.

[0099] In some embodiments, the target impedance value is the product of the target inductive reactance value and a preset ratio coefficient.

[0100] 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.

[0101] 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.

[0102] Based on the same inventive concept, an embodiment of the present application further provides an electronic device.

[0103] Figure 6 It is a schematic structural diagram of the electronic device provided by the embodiment of the present application. As Figure 6 shown, the electronic device 60 of this embodiment includes: at least one processor 610 ( Figure 6 only one is shown in the figure), a memory 620, and a communication module 640. A computer program 630 that may run on the processor 610 is stored in the memory 620. When the processor 610 executes the computer program 630, the steps in the embodiment of the above-mentioned distribution line distance protection method are implemented, such as Figure 2 the steps S201 to S204 shown in Figure 3 or the steps S301 to S304 shown in Figure 5 Or, when the processor 610 executes the computer program 630, the functions of each module / unit in the above-mentioned device embodiments are implemented, such as Figure 5 the functions of the modules 510 to 520 shown in

[0104] The communication module 640 can be a separate communication unit for communicating with an external server or a terminal device. The electronic device 60 may include, but is not limited to: a processor 610 and a memory 620. Those skilled in the art can understand that Figure 6 this is only an example of the electronic device 60, and does not constitute a limitation on the electronic device 60. It may include more or fewer components than shown in the figure, or combine certain components, or different components. For example, the electronic device 60 may further include an input and sending device, a network access device, a bus, etc.

[0105] The processor 610 may be a central processing unit (CPU), or may also be 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. The general-purpose processor may be a microprocessor or the processor may also be any conventional processor, etc.

[0106] The memory 620 can be an internal storage unit of the electronic device 60 in some embodiments, such as the hard disk or memory of the electronic device 60. The memory 620 can also be an external storage device of the electronic device 60, such as a plug-in hard disk equipped on the electronic device 60, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. The memory 620 can also include both the internal storage unit of the electronic device 60 and the external storage device. The memory 620 is used to store an operating system, application programs, a BootLoader, data, and other programs, such as the program code of the computer program 630. The memory 620 can also be used to temporarily store the data that has been sent or will be sent.

[0107] In addition, those skilled in the art can clearly understand that, for the convenience and conciseness of description, only the above-mentioned division of each functional unit and module is used as an example. In practical applications, the above functions can be allocated to different functional units and modules as needed, that is, the internal structure of the device is divided into different functional units or modules to complete all or part of the functions described above. In each embodiment of the present application, each functional unit can be integrated in a processing unit, or each unit can exist physically alone, 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 a software functional unit.

[0108] The embodiment of the present application provides a computer-readable storage medium. The computer-readable storage medium stores a computer program. When the computer program runs on an electronic device, the electronic device is enabled to execute the steps in each of the above method embodiments.

[0109] The embodiment of the present application provides a chip. The chip includes a processor and a memory. The memory stores a computer program. When the computer program is executed by the processor, the steps in each of the above method embodiments are implemented.

[0110] The embodiment of the present application provides a computer program product. When the computer program product runs on an electronic device, the electronic device is enabled to execute the steps in each of the above method embodiments.

[0111] It should be understood that the processor mentioned in the embodiments of the present application may be a central processing unit (CPU), or may also be 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. The general-purpose processor may be a microprocessor or any conventional processor, etc.

[0112] 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 RAMbus RAM (DR RAM).

[0113] Those skilled in the art can clearly understand that, for the convenience and conciseness of description, only the above division of each functional unit and module is used as an example. In actual applications, the above functions can be allocated to different functional units and modules according to needs, 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. Each functional unit and module in the embodiments can be integrated into a processing unit, or each unit can exist physically alone, or two or more units can be integrated into one unit. The above integrated unit can be implemented in the form of hardware or in the form of a software functional unit. In addition, the specific names of each functional unit and module are only for the convenience of mutual distinction and do not limit the protection scope of this application. The specific working processes of the units and modules in the above system can refer to the corresponding processes in the foregoing method embodiments and will not be elaborated here.

[0114] In the above embodiments, the descriptions of the various embodiments have their own emphases. For the parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0115] Those of ordinary skill in the art can realize that the units and algorithm steps of the examples described in conjunction with the embodiments disclosed herein can be implemented by electronic hardware, or by a combination of computer software and electronic hardware. Whether these functions are executed in the form of hardware or software depends on the specific application and design constraints of the technical solution. Professionals can use different methods to implement the described functions for each specific application, but such implementation should not be considered to exceed the scope of this application.

[0116] In the embodiments provided in this application, it should be understood that the disclosed device and method can be implemented in other ways. For example, the system embodiments described above are only illustrative. For example, the division of the modules or units is only a logical function division. In actual implementation, there can be other division methods. For example, 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 displayed or discussed couplings or direct couplings or communication connections to each other can be through some interfaces. The indirect couplings or communication connections of the devices or units can be in electrical, mechanical or other forms.

[0117] The units described as separate components may or may not be physically separated, and the components displayed as units may or may not be physical units, that is, they can be located in one place or distributed to multiple network units. Some or all of the units can be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0118] In addition, each functional unit in various embodiments of the present application may be integrated into one processing unit, may exist physically separately for each unit, 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 a software functional unit.

[0119] If the above-mentioned integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it may be stored in a computer-readable storage medium. Based on such an understanding, to implement all or part of the processes in the above-mentioned embodiment methods of the present application, a computer program may be used to instruct relevant hardware to complete. The computer program may be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps of the above-mentioned various method embodiments may be implemented. Among them, the computer program includes computer program code, and the computer program code may be in the form of source code, object code, executable file or some intermediate form, etc. The computer-readable medium may at least include: any entity or device capable of carrying the computer program code to the large-screen device, recording medium, computer memory, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), electrical carrier signal, telecommunication signal, and software distribution medium. For example, a USB flash drive, a mobile hard disk, a magnetic disk or an optical disc, etc. In some jurisdictions, according to legislation and patent practice, the computer-readable medium may not be an electrical carrier signal and a telecommunication signal.

[0120] Finally, it should be noted that the above are only specific embodiments 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 covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A distance protection method for a distribution line, characterized in that, Applied to a first line protection device for monitoring the line state of a first line segment, the method includes: Obtaining a first measured impedance corresponding to a fault phase, and obtaining a preset unit inductive reactance value and a preset differential time; Determining a target impedance rate according to the preset unit inductive reactance value, the preset differential time, and a first time interval, where the target impedance rate is positively correlated with the preset unit inductive reactance value, the target impedance rate is negatively correlated with the preset differential time, the start time of the first time interval is the fault time, and the end time of the first time interval is the current time; Determining a target inductive reactance value and a target impedance value according to the target impedance rate, where both the target inductive reactance value and the target impedance value are positively correlated with the target impedance rate; If the absolute value of the real part impedance of the first measured impedance is less than the target impedance value, and the absolute value of the imaginary part inductive reactance of the first measured impedance is less than the target inductive reactance value, then send a disconnection instruction to the circuit breaker, where the disconnection instruction is used to instruct the circuit breaker to change the line state to a disconnected state.

2. The distance protection method for a distribution line according to claim 1, wherein Before the step of sending the disconnection instruction to the circuit breaker, it further includes: Continuously obtaining a plurality of second measured impedances corresponding to the fault phase within a preset time period based on a preset sampling frequency, where the preset time period is a time period after the current time and separated from the current time by a second time interval.

3. The distance protection method for a distribution line according to claim 2, wherein The sending the disconnection instruction to the circuit breaker includes: If the absolute value of the real part impedance of the plurality of second measured impedances is less than the target impedance value, and the absolute value of the imaginary part inductive reactance of the plurality of second measured impedances is less than the target inductive reactance value, then send the disconnection instruction to the circuit breaker.

4. The distance protection method for a distribution line according to claim 1, characterized in that The obtaining the first measured impedance corresponding to the fault phase includes: Obtaining a plurality of first line currents at a first time, where the first time is any time before the first line protection device starts the distance protection process; If there is a line current greater than or equal to a preset overcurrent setting value among the plurality of first line currents, then record the first time as the fault time, and determine the phase corresponding to the line current with the largest current amplitude among the plurality of first line currents as the fault phase; Obtaining a second line voltage and a second line current corresponding to the fault phase at a second time; Determining the ratio of the second line voltage to the second line current as the first measured impedance.

5. The distance protection method for a distribution line according to claim 1, characterized in that, The length of the first line segment is a first line length, the lower-level line protection device adjacent to the first line protection device is a second line protection device for monitoring the line state of a second line segment, and the length of the second line segment is a second line length; The determining the target impedance rate according to the preset unit inductive reactance value, the preset differential time, and the first time interval includes: If the first time interval is less than or equal to the preset differential time, then determine the target impedance rate as a first ratio of the product of the preset unit inductive reactance value and the first line length to the preset differential time; If the first time interval is greater than the preset differential time and less than or equal to twice the preset differential time, determine that the target impedance rate is the second ratio of the product of the preset unit inductive reactance value and the second line length to the preset differential time; If the first time interval is greater than twice the preset differential time, determine that the target impedance rate is the smaller value of the first ratio and the second ratio.

6. The distance protection method for a distribution line according to claim 5, wherein, The determining the target inductive reactance value and the target impedance value according to the target impedance rate includes: If the first time interval is less than or equal to the preset differential time, determine that the target inductive reactance value is the product of the target impedance rate and the first time interval; If the first time interval is greater than the preset differential time and less than or equal to twice the preset differential time, determine that the target inductive reactance value is the sum of a first summand and a second summand, the first summand is the product of the preset unit inductive reactance value and the first line length, and the second summand is the product of the difference between the first time interval and the preset differential time and the target impedance rate; If the first time interval is greater than twice the preset differential time, determine that the target inductive reactance value is the sum of a third summand and a fourth summand, the third summand is the product of the sum of the first line length and the second line length and the preset unit inductive reactance value, and the fourth summand is the product of the difference between the first time interval and twice the preset differential time and the target impedance rate; Determine the target impedance value according to the target impedance rate and the preset ratio coefficient, and the target impedance value is positively correlated with the target inductive reactance value and the preset ratio coefficient.

7. The distance protection method for a distribution line according to claim 5, characterized in that, If there is no second line protection device, assign the value of the first line length to the second line length.

8. The distance protection method for a distribution line according to any one of claims 1 to 7, characterized in that The target impedance value is the product of the target inductive reactance value and the preset ratio coefficient.

9. An electronic device, characterized in that, It includes a processor and a memory, and the processor is used to execute the computer program stored in the memory to implement the distribution line distance protection method described in any one of the above claims 1-8.

10. A computer-readable storage medium storing a computer program, characterized in that, When the computer program is executed by the processor, it implements the distribution line distance protection method described in any one of the above claims 1-8.

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