Protection device starting method and device, terminal equipment and computer program product

Abstract

The invention relates to a protection device starting method and device, terminal equipment and a computer program product, and the method comprises the steps: obtaining three-phase current and zero-sequence current of a target interval at a plurality of continuous sampling points of a first cycle wave and a second cycle wave, the second cycle wave being before the first cycle wave and being separated from the first cycle wave by a cycle wave period; respectively calculating a first sum of squares of the three-phase current and the zero-sequence current at each sampling point; calculating a current break variable at each sampling point based on the first sum of squares at each sampling point; and according to the current break variable at each sampling point and a preset first short-circuit judgment rule, determining whether a short-circuit fault occurs in the target interval, and starting a protection device corresponding to the target interval under the condition that the short-circuit fault occurs in the target interval. According to the application, the problem that the starting element of the protection device is low in sensitivity of short-circuit fault detection is solved, and the technical effect of improving the sensitivity of the starting element of the protection device for short-circuit fault detection is achieved.

Description

Technical Field

[0001] This application belongs to the technical field of relay protection, and particularly relates to a starting method, device, terminal device, and computer program product for a protection device. Background Technique

[0002] The continuous development of high-voltage and extra-high-voltage power grid technologies has put forward higher requirements for the speed and reliability of relay protection. The rapid and accurate removal of faults by relay protection and the timely avoidance of the impact of faults on the entire power grid are beneficial to the safety and stability of the power system to ensure reliable and continuous power supply to non-faulty lines.

[0003] Microcomputer protection devices (also known as protection devices) are an important part of relay protection. In protection devices, starting elements located in the interrupt service program are usually used to sensitively and quickly detect fault disturbances in the power system. After determining that there are fault disturbances in the power system, complex fault processing is further completed through the protection device. Currently, common starting elements often determine whether there is a short-circuit fault in the power system by detecting the sudden change of phase current or the amplitude of zero-sequence current. However, when a short-circuit fault occurs in new energy power systems such as photovoltaic power generation and wind power generation, the sudden change of phase current or the amplitude of zero-sequence current is small, and existing starting elements may not be able to detect short-circuit faults in time, resulting in slow startup of the protection device and even damage to the power system.

[0004] Currently, there is no effective solution to the problem of low sensitivity of the starting element of the protection device in detecting short-circuit faults in related technologies. Summary of the Invention

[0005] Embodiments of this application provide a starting method, device, terminal device, and computer program product for a protection device to at least solve the problem of low sensitivity of the starting element of the protection device in detecting short-circuit faults in related technologies.

[0006] In a first aspect, embodiments of this application provide a starting method for a protection device, including: obtaining a plurality of consecutive sampling points in the first cycle of a target interval, as well as three-phase currents and zero-sequence currents at a plurality of consecutive sampling points in the second cycle, where the second cycle is before the first cycle and is one cycle period away from the first cycle; respectively calculating the first sum of squares of the three-phase currents and the zero-sequence current at each of the sampling points; based on the first sum of squares at each of the sampling points, calculating the current sudden change at each of the sampling points according to the following mathematical expression:

[0007] Δdi N1 2 =di N1 2 -di N52 ;

[0008] di N1 2 = |i N1 2 -i N2 2 |;

[0009] wherein, i N1 2 , i N2 2 are respectively the first sum of squares at the sampling point N1 and at the previous sampling point N2 of the sampling point N1, and di N1 2 , di N5 2 are respectively the difference of the first sum of squares at the sampling point N1 and at the sampling point N5, and Δdi N1 2 is the sudden change amount of current at the sampling point N1. The sampling point N5 is before the sampling point N1 and is separated from the sampling point N1 by a period of one cycle; According to the sudden change amount of current at each sampling point and a preset first short - circuit determination rule, it is determined whether a short - circuit fault occurs in the target interval, and when the short - circuit fault occurs in the target interval, the protection device corresponding to the target interval is started.

[0010] In some embodiments, determining whether a short - circuit fault occurs in the target interval according to the sudden change amount of current at each sampling point and a preset first short - circuit determination rule includes: judging whether the sudden change amounts of current at the sampling point N1, the sampling point N2, and the previous sampling point N3 of the sampling point N2 satisfy the first short - circuit determination rule, wherein the first short - circuit determination rule is expressed as:

[0011] Δdi N3 2 > (k1 * I set ) 2 ;

[0012] Δdi N2 2 + Δdi N3 2 > (k2 * I set ) 2 ;

[0013] Δdi N1 2 + Δdi N2 2 + Δdi N3 2 > (k3 * I set) 2 ;

[0014] wherein, I set is the preset starting threshold current value of the protection device, and k1, k2, and k3 are respectively the preset first weight coefficient, second weight coefficient, and third weight coefficient; when the current mutation amounts at the sampling point N1, the sampling point N2, and the sampling point N3 satisfy the first short-circuit determination rule, it is determined that a short-circuit fault occurs in the target interval; when the current mutation amounts at the sampling point N1, the sampling point N2, and the sampling point N3 do not satisfy the first short-circuit determination rule, it is determined that no short-circuit fault occurs in the target interval.

[0015] In some embodiments, the first weight coefficient is less than the second weight coefficient, and the second weight coefficient is less than the third weight coefficient.

[0016] In some embodiments, after determining whether a short-circuit fault occurs in the target interval according to the current mutation amounts at each sampling point and the preset first short-circuit determination rule, the method further includes: obtaining the three-phase voltages and zero-sequence voltage at the multiple consecutive sampling points of the target interval in the first cycle and the second cycle; respectively calculating the second sum of squares of the three-phase voltages and the zero-sequence voltage at each sampling point; based on the second sum of squares at each sampling point, calculating the voltage mutation amount at each sampling point according to the following mathematical expression:

[0017] Δdu N1 2 = du N1 2 - du N5 2 ;

[0018] du N1 2 = |u N1 2 - u N2 2 |;

[0019] wherein, u N1 2 , i N2 2 are respectively the second sum of squares at the sampling point N1 and the sampling point N2, du N1 2 , du N5 2 are respectively the differences of the second sum of squares at the sampling point N1 and the sampling point N5, and Δdu N1 2is the voltage mutation amount at the sampling point N1; according to the voltage mutation amounts at each of the sampling points and a preset second short - circuit determination rule, determine whether the short - circuit fault occurs in the target interval.

[0020] In some embodiments, determining whether the short - circuit fault occurs in the target interval according to the voltage mutation amounts at each of the sampling points and a preset second short - circuit determination rule includes: determining whether the voltage mutation amounts at the sampling point N1, the sampling point N2, and the previous sampling point N3 of the sampling point N2 satisfy the second short - circuit determination rule, where the second short - circuit determination rule is expressed as:

[0021] Δdu N3 2 >(k4*U set ) 2 ;

[0022] Δdu N2 2 +Δdu N3 2 >(k5*U set ) 2 ;

[0023] Δdu N1 2 +Δdu N2 2 +Δdu N3 2 >(k6*U set ) 2 ;

[0024] where U set is the starting threshold voltage value of the preset protection device, and k4, k5, and k6 are the preset fourth weight coefficient, fifth weight coefficient, and sixth weight coefficient respectively; when the voltage mutation amounts at the sampling point N1, the sampling point N2, and the sampling point N3 satisfy the second short - circuit determination rule, determine that the short - circuit fault occurs in the target interval; when the voltage mutation amounts at the sampling point N1, the sampling point N2, and the sampling point N3 do not satisfy the second short - circuit determination rule, determine that the short - circuit fault does not occur in the target interval.

[0025] In some embodiments, the fourth weight coefficient is less than the fifth weight coefficient, and the fifth weight coefficient is less than the sixth weight coefficient.

[0026] In some embodiments, the period of one cycle is 20 ms.

[0027] Second aspect, an embodiment of the present application provides a starting device for a protection device, including: an acquisition module, configured to acquire a plurality of consecutive sampling points of a target interval in a first cycle, and three-phase currents and zero-sequence currents at a plurality of consecutive sampling points in a second cycle, where the second cycle is before the first cycle and is separated from the first cycle by a cycle period; a first calculation module, configured to calculate a first sum of squares of the three-phase currents and the zero-sequence current at each of the sampling points respectively; a second calculation module, configured to calculate a current mutation amount at each of the sampling points based on the first sum of squares at each of the sampling points according to the following mathematical expression:

[0028] Δdi N1 2 =di N1 2 -di N5 2 ;

[0029] di N1 2 =|i N1 2 -i N2 2 |;

[0030] Wherein, i N1 2 , i N2 2 are the first sum of squares at sampling point N1 and the previous sampling point N2 of sampling point N1 respectively, di N1 2 , di N5 2 are the differences of the first sum of squares at sampling point N1 and sampling point N5 respectively, Δdi N1 2 is the current mutation amount at sampling point N1, sampling point N5 is before sampling point N1 and is separated from sampling point N1 by the cycle period; a starting module, configured to determine whether a short-circuit fault occurs in the target interval according to the current mutation amount at each of the sampling points and a preset first short-circuit determination rule, and start a protection device corresponding to the target interval when the short-circuit fault occurs in the target interval.

[0031] Third aspect, an embodiment of the present application provides a terminal device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the computer program, the starting method of the protection device in any one of the above first aspects is implemented.

[0032] Fourthly, an embodiment of the present application provides a computer program product, including a computer program, which when running, causes the startup method of the protection device described in any item of the first aspect above to be executed.

[0033] Compared with the related art, for the startup method, device, terminal device, and computer program product of the protection device provided by the embodiments of the present application, by obtaining the three-phase currents and zero-sequence current at multiple consecutive sampling points in the first cycle and the second cycle of the target interval, and respectively calculating the first sum of squares of the three-phase currents and the zero-sequence current at each sampling point, then calculating the current mutation amount at each sampling point based on the first sum of squares at each sampling point, and finally determining whether a short-circuit fault occurs in the target interval according to the current mutation amount at each sampling point and a preset first short-circuit determination rule, and starting the protection device corresponding to the target interval when a short-circuit fault occurs in the target interval. In this way, the three-phase currents and the zero-sequence current are combined, the first sum of squares is calculated, and the current mutation amount is calculated based on the first sum of squares, and then the current mutation amount is used as the basis for determining whether a short-circuit fault occurs in the target interval. In a new energy power system such as photovoltaic power generation and wind power generation, where the mutation amount of the phase current or the amplitude of the zero-sequence current is small when a short-circuit fault occurs, the fault disturbance existing in the power system can be detected more sensitively. Through the present application, the problem that the startup element of the protection device in the related art has low sensitivity to short-circuit fault detection is solved, and the technical effect of improving the sensitivity of the startup element of the protection device to short-circuit fault detection is achieved.

[0034] Details of one or more embodiments of the present application are set forth in the following drawings and description, so that other features, objects, and advantages of the present application will become more comprehensible. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] 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 following drawings 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.

[0036] Figure 1 is a flowchart of a startup method of a protection device according to an embodiment of the present application;

[0037] Figure 2 is a flowchart of a startup method of a protection device according to another embodiment of the present application;

[0038] Figure 3 is a schematic structural diagram of a startup device of a protection device according to an embodiment of the present application;

[0039] Figure 4 It is a schematic structural diagram of a terminal device according to an embodiment of the present application. Detailed implementation manners

[0040] In the following description, for the purpose of illustration rather than limitation, specific details such as specific system architectures and technologies are presented in order 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.

[0041] 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.

[0042] It should also be understood that the term "and / or" 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.

[0043] As used in the specification of the present application and the appended claims, the term "if" can be interpreted as "when", "once", "in response to determining", or "in response to detecting" depending on the context. Similarly, the phrase "if determined" or "if detecting [the described condition or event]" can be interpreted as meaning "once determined", "in response to determining", "once detecting [the described condition or event]", or "in response to detecting [the described condition or event]" depending on the context.

[0044] 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.

[0045] The reference to "an embodiment" or "some embodiments" etc. described in the specification of the present application means that a specific feature, structure, or characteristic described in connection with that embodiment is included in one or more embodiments of the present application. Thus, the statements "in an 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 in another way. The terms "comprising", "including", "having", and their variants all mean "including but not limited to", unless otherwise specifically emphasized in another way.

[0046] The continuous development of high-voltage and extra-high-voltage power grid technologies has put forward higher requirements for the speed and reliability of relay protection. The rapid and accurate removal of faults by relay protection and the timely avoidance of the impact of faults on the entire power grid are beneficial to the safety and stability of the power system, so as to ensure reliable and continuous power supply to non-faulty lines.

[0047] Microcomputer protection devices (also known as protection devices) are an important part of relay protection. In protection devices, starting elements located in the interrupt service program are usually used to sensitively and quickly detect fault disturbances in the power system. After determining that there are fault disturbances in the power system, the protection device further completes complex fault processing.

[0048] The starting element of the protection device is a key step in the operation of the protection logic. One of the functions of the starting element is to quickly detect different types of short-circuit faults, so that the protection device can perform the fault judgment program. When the starting element does not detect a short-circuit fault, the protection device will not perform the fault judgment. Commonly used starting elements include current mutation starting elements and zero-sequence overcurrent starting elements. The judgment logic of the current mutation starting element depends on the fact that the current will change to a certain extent when a short-circuit fault occurs in the power system. Therefore, when the fault characteristics are not obvious, for example, when a high-resistance grounding fault occurs, the current mutation starting element may not be able to start normally; the judgment logic of the zero-sequence overcurrent starting element depends on the zero-sequence current generated when a grounding fault occurs in the power system. However, when other faults occur in the power system without a grounding fault, the zero-sequence overcurrent starting element is invalid.

[0049] At present, commonly used starting elements often judge whether there is a short-circuit fault in the power system by detecting the mutation of phase current or the magnitude of zero-sequence current. However, new energy power systems such as photovoltaic power generation and wind power generation usually use power electronic devices to convert direct current into alternating current and then send it into the power grid. Since the overcurrent capacity of power electronic devices themselves is relatively weak, current limiting conditions will be added to the control strategy of power electronic devices to limit the magnitude of the current and prevent damage to power electronic devices. Therefore, when a short-circuit fault occurs in such a power system, due to the influence of the above control strategy, it will show obvious weak-feed characteristics. That is, when a short-circuit fault occurs in such a power system, the mutation of phase current or the magnitude of zero-sequence current is small, and existing starting elements may not be able to detect the short-circuit fault in time, resulting in slow startup of the protection device or even damage to the power system.

[0050] At present, no effective solution has been proposed for the problem that the starting element of the protection device in the related technology has low sensitivity to short-circuit fault detection.

[0051] In view of this, an embodiment of the present application provides a method for starting a protection device. By obtaining the three-phase currents and zero-sequence current at multiple consecutive sampling points of a target interval in the first cycle and the second cycle, and respectively calculating the first sum of squares of the three-phase currents and the zero-sequence current at each sampling point, then calculating the current mutation amount at each sampling point based on the first sum of squares at each sampling point, and finally determining whether a short-circuit fault occurs in the target interval according to the current mutation amount at each sampling point and a preset first short-circuit determination rule, and starting the protection device corresponding to the target interval when a short-circuit fault occurs in the target interval. In this way, the three-phase currents and the zero-sequence current are combined, the first sum of squares is calculated through them, and the current mutation amount is calculated based on the first sum of squares, so as to use the current mutation amount as the basis for determining whether a short-circuit fault occurs in the target interval. In a new energy power system such as photovoltaic power generation and wind power generation where the mutation amount of the phase current or the amplitude of the zero-sequence current is small when a short-circuit fault occurs, the fault disturbance existing in the power system can be detected more sensitively. Through the present application, the problem that the starting element of the protection device in the related art has low sensitivity to short-circuit fault detection is solved, and the technical effect of improving the sensitivity of the starting element of the protection device to short-circuit fault detection is achieved.

[0052] The following will be combined with Figure 1 to illustrate the method for starting a protection device provided by an embodiment of the present application. Please refer to Figure 1 , Figure 1 is a flowchart of the method for starting a protection device according to an embodiment of the present application. As Figure 1 shown, the method includes:

[0053] Step S101, obtain the three-phase currents and the zero-sequence current at multiple consecutive sampling points of a target interval in the first cycle and at multiple consecutive sampling points of the target interval in the second cycle, where the second cycle is before the first cycle and is separated from the first cycle by a cycle period.

[0054] In this embodiment, the target interval is the interval protected by the protection device. The target interval can be a line interval or a transformer interval.

[0055] In one embodiment, the protection device corresponding to the target interval can collect the three-phase current and zero-sequence current of the target interval in real time. For example, the protection device can collect the three-phase current and zero-sequence current at four consecutive sampling points N1, N2, N3, and N4 in the first cycle of the target interval (the sampling time of sampling point N1 is after that of sampling point N2, the sampling time of sampling point N2 is after that of sampling point N3, and the sampling time of sampling point N3 is after that of sampling point N4), and can collect the three-phase current and zero-sequence current at four consecutive sampling points N5, N6, N7, and N8 in the second cycle of the target interval. Among them, the second cycle is separated from the first cycle by a cycle period, and the cycle period of this one cycle is 20 ms. 24 sampling points can be sampled within each cycle, that is, the sampling time interval between every two sampling points is 0.833… ms.

[0056] In this embodiment, sampling point N1 is separated from sampling point N5 by a cycle period, and the sampling time of sampling point N1 is after that of sampling point N5. For example, assuming that sampling point N5 is sampled at time t, then sampling point N1 is sampled at time t + 20 ms. Similar to sampling points N1 and N5, sampling point N2 is also separated from sampling point N6 by 20 ms, and the sampling time of sampling point N2 is after that of sampling point N6; sampling point N3 is also separated from sampling point N7 by 20 ms, and the sampling time of sampling point N3 is after that of sampling point N7; sampling point N4 is also separated from sampling point N8 by 20 ms, and the sampling time of sampling point N4 is after that of sampling point N8.

[0057] In one embodiment, the zero-sequence current of the target interval can be obtained according to the following mathematical expression:

[0058] i0 = i A + i B + i C ;

[0059] where, i A , i B , i C are the phase currents of the target interval under phase A, phase B, and phase C respectively, and i0 is the zero-sequence current of the target interval.

[0060] When the target interval is operating normally, the three-phase currents should be symmetrical. Therefore, the zero-sequence current of the target interval should be zero. Specifically, when the target interval is operating normally, the current is a sine wave with a frequency of 50 Hz. Taking the current as an example:

[0061] i A = Asin(ωt + α);

[0062] i B = Asin(ωt + β);

[0063] iC = Asin(ωt + γ);

[0064] Wherein, the phase currents of the target interval are symmetrical under the A-phase, B-phase, and C-phase, α, β, and λ are the initial angles of the three-phase currents, and α + β + λ = 360 0 , therefore, i0 = i A + i B + i C = 0.

[0065] Step S102, calculate the first sum of squares of the three-phase currents and the zero-sequence current at each sampling point respectively.

[0066] In this embodiment, the first sum of squares of the three-phase currents and the zero-sequence current at each sampling point can be calculated according to the following mathematical expression:

[0067] i N1 2 = i A 2 + i B 2 + i C 2 + i0 2 ;

[0068] Wherein, i N1 2 is the first sum of squares at the sampling point N1, i A , i B , i C are the three-phase currents of the target interval at the sampling point N1, and i0 is the zero-sequence current of the target interval at the sampling point N1.

[0069] Step S103, based on the first sum of squares at each sampling point, calculate the current mutation amount at each sampling point according to the following mathematical expression:

[0070] Δdi N1 2 = di N1 2 - di N5 2 ;

[0071] di N1 2 = |i N1 2 - i N2 2 |;

[0072] Wherein, i N1 2 , i N2 2The first sum of squares at the sampling point N1 and the previous sampling point N2 of the sampling point N1, respectively, is di N1 2 and di N5 2 The difference in the first sum of squares at the sampling point N1 and the sampling point N5, respectively, is Δdi N1 2 is the sudden change in current at the sampling point N1. The sampling point N5 is before the sampling point N1 and is one cycle away from the sampling point N1.

[0073] Step S104: Determine whether a short - circuit fault occurs in the target interval according to the sudden change in current at each sampling point and a preset first short - circuit determination rule, and start the protection device corresponding to the target interval when a short - circuit fault occurs in the target interval.

[0074] In this embodiment, when the target interval is operating normally, its three - phase current and three - phase voltage are stable sinusoidal waveforms that are three - phase symmetric. Therefore, its zero - sequence current and zero - sequence voltage are zero. Taking the current as an example:

[0075]

[0076] Therefore, di N1 2 =|i N1 2 -i N2 2 | = 0, that is, when the target interval is operating normally, the difference in the first sum of squares calculated at each sampling point is zero, and thus the sudden change in current Δdi N1 2 =di N1 2 -di N5 2 = 0.

[0077] However, when a short - circuit fault occurs in the target interval, although its three - phase current and three - phase voltage may change very little. For example, new - energy power systems such as photovoltaic power generation and wind power generation will exhibit obvious weak - feed characteristics. However, by calculating the sudden change in current at three consecutive sampling points, combining the three - phase current with the zero - sequence current, calculating their first sum of squares, and calculating the sudden change in current based on this first sum of squares, and then using the sudden change in current as the basis for determining whether a short - circuit fault occurs in the target interval. Since the three - phase current of the target interval remains basically unchanged when it is operating normally, the sudden change in current Δdi Nm 2 is zero, while when a short - circuit fault occurs in the target interval, the sudden change in current Δdi Nm 2There will be characteristics with large variations. By utilizing the sudden change in current Δdi at the current sampling point and the two consecutive sampling points before the current sampling point Nm 2 Performing the startup logic judgment of the protection device can more sensitively and accurately detect the current change when a short - circuit fault occurs in the target interval, so that the protection device can quickly perform the protection logic judgment, which is of great significance for quickly clearing the fault, reducing equipment damage caused by the fault, and ensuring the safety of the power grid.

[0078] In this embodiment, determining whether a short - circuit fault occurs in the target interval according to the sudden change in current at each sampling point and a preset first short - circuit determination rule includes the following steps:

[0079] Step 1, determine whether the sudden change in current at sampling point N1, sampling point N2, and the previous sampling point N3 of sampling point N2 satisfies the first short - circuit determination rule, where the first short - circuit determination rule is expressed as:

[0080] Δdi N3 2 >(k1*I set ) 2 ;

[0081] Δdi N2 2 +Δfi N3 2 >(k2*I set ) 2 ;

[0082] Δdi N1 2 +Δdi N2 2 +Δdi N3 2 >(k3*I set ) 2 ;

[0083] where, I set is the preset startup threshold current value of the protection device, and k1, k2, and k3 are the preset first weight coefficient, second weight coefficient, and third weight coefficient respectively.

[0084] In this embodiment, the preset startup threshold current value of the protection device can be set according to the type of the target interval. For example, when the target interval is a line interval, I set can be set based on the preset minimum short - circuit current of the line interval; when the target interval is a transformer interval, I set can be set based on the rated current of each side of the preset transformer.

[0085] For example, taking the line interval as an example, when a line fault occurs, the primary value of the short-circuit current is usually considered to be not less than 300 A. Then, the secondary value is taken according to the actual project transformation ratio. Assuming the transformation ratio is 1000 A / 1 A, then I set = 0.3 A; taking the transformer interval as an example, S e is the rated capacity of the transformer, V e is the rated voltage of each side of the transformer, and K CT is the CT transformation ratio of each side of the transformer.

[0086] In one embodiment, the first weight coefficient is less than the second weight coefficient, and the second weight coefficient is less than the third weight coefficient. For example, k1 = 0.05, k2 = 0.15, k3 = 0.3. It should be noted that the first weight coefficient, the second weight coefficient, and the third weight coefficient are the current sensitivity coefficients of the starting threshold current value, which affect the starting sensitivity of the protection device. Therefore, the specific parameters of the above-mentioned first weight coefficient, second weight coefficient, and third weight coefficient can be set according to the actual application scenario of the starting method of the protection device provided in the embodiments of the present application and the sensitivity required by the user.

[0087] Step 2, when the current mutation amounts at the sampling points N1, N2, and N3 satisfy the first short-circuit determination rule, it is determined that a short-circuit fault has occurred in the target interval.

[0088] Step 3, when the current mutation amounts at the sampling points N1, N2, and N3 do not satisfy the first short-circuit determination rule, it is determined that no short-circuit fault has occurred in the target interval.

[0089] In this embodiment, it is possible to determine whether a short-circuit fault has occurred in the target interval based on the current mutation amounts corresponding to the sampling point N1, the previous sampling point N2 of the sampling point N1, and the previous sampling point N3 of the sampling point N2. When the current mutation amounts at the sampling points N1, N2, and N3 satisfy the first short-circuit determination rule, it is determined that a short-circuit fault has occurred in the target interval. At this time, the protection device corresponding to the target interval can be started, so that the protection device starts the fault judgment program and performs subsequent fault processing. In this way, the three-phase current and the zero-sequence current are combined, the first sum of squares is calculated, and the current mutation amount is calculated based on the first sum of squares. Furthermore, the current mutation amount is used as the basis for determining whether a short-circuit fault has occurred in the target interval. In a new energy power system such as photovoltaic power generation and wind power generation, where the mutation amount of the phase current or the amplitude of the zero-sequence current is small when a short-circuit fault occurs, the starting method of the protection device provided in the embodiments of the present application can more sensitively detect the fault disturbance existing in the power system.

[0090] In addition, in addition to using the current mutation amount Δdi Nm 2In addition to serving as a basis for determining whether a short - circuit fault occurs in the target interval, the voltage mutation ΔfU can also be used Nm 2 as a basis for determining whether a short - circuit fault occurs in the target interval. By using the current mutation Δfi Nm 2 and the voltage mutation ΔfU Nm 2 as a basis for determining whether a short - circuit fault occurs in the target interval, multiple bases can be provided for the starting logic judgment of the protection device, further improving the sensitivity and accuracy of the starting element of the protection device for short - circuit fault detection, so that the protection device can quickly perform protection logic judgment and quickly cut off the fault.

[0091] Next, the starting method of the protection device provided in another embodiment of the present application will be described in conjunction with Figure 2 . Please refer to Figure 2 , Figure 2 which is a flowchart of the starting method of the protection device according to another embodiment of the present application. As shown in Figure 2 , the method includes:

[0092] Step S201: Obtain the three - phase voltages and zero - sequence voltage at multiple consecutive sampling points of the target interval in the first cycle and the second cycle.

[0093] In this embodiment, the zero - sequence voltage of the target interval can be obtained according to the following mathematical expression:

[0094] u0 = u A + u B + u C ;

[0095] where u A , u B , u C are the phase voltages of the target interval under phase A, phase B, and phase C respectively, and u0 is the zero - sequence voltage of the target interval.

[0096] Step S202: Calculate the second sum of squares of the three - phase voltages and the zero - sequence voltage at each sampling point respectively.

[0097] In this embodiment, the second sum of squares of the three - phase voltages and the zero - sequence voltage at each sampling point can be calculated according to the following mathematical expression:

[0098] i N1 2 = i A 2 + i B 2 + i C 2 + i0 2 ;

[0099] wherein, u N1 2 is the second sum of squares at sampling point N1, and u A , u B , u C are the three-phase voltages of the target interval at sampling point N1, and u0 is the zero-sequence voltage of the target interval at sampling point N1.

[0100] Step S203, based on the second sum of squares at each sampling point, calculate the voltage mutation amount at each sampling point according to the following mathematical expression:

[0101] Δdu N1 2 = du N1 2 - du N5 2 ;

[0102] dyu N1 2 = |u N1 2 - u N2 2 |;

[0103] wherein, u N1 2 , u N2 2 are the second sum of squares at sampling points N1 and N2 respectively, du N1 2 , du N5 2 are the differences of the second sum of squares at sampling points N1 and N5 respectively, and Δdu N1 2 is the voltage mutation amount at sampling point N1.

[0104] Step S204, according to the voltage mutation amount at each sampling point and the preset second short-circuit determination rule, determine whether a short-circuit fault occurs in the target interval.

[0105] In one embodiment, determining whether a short-circuit fault occurs in the target interval according to the voltage mutation amount at each sampling point and the preset second short-circuit determination rule includes the following steps:

[0106] Step 1, determine whether the voltage mutation amounts at sampling points N1, N2, and the previous sampling point N3 of sampling point N2 satisfy the second short-circuit determination rule, wherein the second short-circuit determination rule is expressed as:

[0107] Δdu n3 2 > (k4 * U set) 2 ;

[0108] Δdu N2 2 +Δdu N3 2 (k5*U set ) 2 ;

[0109] Δdu N1 2 +Δdu N2 2 +Δdu N3 2 (k6*U set ) 2 ;

[0110] wherein, U set is the starting threshold voltage value of the preset protection device, and k4, k5, and k6 are respectively the preset fourth weight coefficient, fifth weight coefficient, and sixth weight coefficient.

[0111] In this embodiment, the starting threshold voltage value U of the protection device can be determined according to the minimum amplitude of the voltage drop during a short circuit preset. set . For example, when the target interval is operating normally, the secondary value of the rated voltage of the power grid is 57.7V. Assuming that when a short circuit fault occurs in the target interval, the voltage drops by a minimum of 0.05 times the rated voltage, then U set = 0.05 × 57.7 = 2.885V.

[0112] In one embodiment, the fourth weight coefficient is less than the fifth weight coefficient, and the fifth weight coefficient is less than the sixth weight coefficient. For example, k4 = 0.05, k5 = 0.15, k6 = 0.3. It should be noted that the fourth weight coefficient, fifth weight coefficient, and sixth weight coefficient are the voltage sensitivity coefficients of the starting threshold voltage value, which affect the starting sensitivity of the protection device. Therefore, the specific parameters of the above fourth weight coefficient, fifth weight coefficient, and sixth weight coefficient can be set according to the actual application scenario of the starting method of the protection device provided in the embodiments of the present application and the sensitivity required by the user.

[0113] Step 2, when the voltage mutation amounts at sampling points N1, N2, and N3 satisfy the second short circuit determination rule, it is determined that a short circuit fault has occurred in the target interval.

[0114] Step 3, when the voltage mutation amounts at sampling points N1, N2, and N3 do not satisfy the second short circuit determination rule, it is determined that no short circuit fault has occurred in the target interval.

[0115] In this embodiment, when the voltage mutation amounts at sampling points N1, N2, and N3 satisfy the second short-circuit determination rule or the current mutation amounts at sampling points N1, N2, and N3 satisfy the first short-circuit determination rule, it can be determined that a short-circuit fault occurs in the target interval.

[0116] Through the above steps S101 to S104 and steps S201 to S204, by obtaining the three-phase currents and zero-sequence currents at multiple consecutive sampling points of the target interval in the first cycle and the second cycle, and respectively calculating the first sum of squares of the three-phase currents and the zero-sequence currents at each sampling point, then calculating the current mutation amount at each sampling point based on the first sum of squares at each sampling point, and finally determining whether a short-circuit fault occurs in the target interval according to the current mutation amount at each sampling point and the preset first short-circuit determination rule, and starting the protection device corresponding to the target interval when a short-circuit fault occurs in the target interval. In this way, the three-phase currents and the zero-sequence currents are combined, the first sum of squares is calculated, and the current mutation amount is calculated based on the first sum of squares, so that the current mutation amount is used as the basis for determining whether a short-circuit fault occurs in the target interval. In a new energy power system such as photovoltaic power generation and wind power generation where the mutation amount of the phase current or the amplitude of the zero-sequence current is small when a short-circuit fault occurs, the fault disturbance existing in the power system can be detected more sensitively. Through the present application, the problem that the starting element of the protection device in the related art has low sensitivity to short-circuit fault detection is solved, and the technical effect of improving the sensitivity of the starting element of the protection device to short-circuit fault detection is achieved.

[0117] It should be understood that the magnitudes of the sequence numbers of the above steps in the embodiments do not mean the order of execution is prior or posterior. The execution order of each process should be determined according to its function and internal logic, and should not constitute any limitation to the implementation process of the embodiments of the present application.

[0118] Corresponding to the starting method of the protection device described in the above embodiments, Figure 3 FIG. shows a structural schematic diagram of a starting device of a protection device according to an embodiment of the present application. For the sake of illustration, only the parts related to the embodiments of the present application are shown.

[0119] Please refer to Figure 3 , the starting device 3 of the protection device includes: an acquisition module 30, configured to acquire the three-phase currents and zero-sequence currents at multiple consecutive sampling points of the target interval in the first cycle and at multiple consecutive sampling points in the second cycle, where the second cycle is before the first cycle and is separated from the first cycle by a cycle period; a first calculation module 31, configured to respectively calculate the first sum of squares of the three-phase currents and the zero-sequence currents at each sampling point; a second calculation module 32, configured to calculate the current mutation amount at each sampling point based on the first sum of squares at each sampling point according to the following mathematical expression:

[0120] Δdi N1 2 =di N1 2 -di N5 2 ;

[0121] di N1 2 =|i N1 2 -i N2 2 |;

[0122] wherein, i N1 2 、i N2 2 are respectively the first sum of squares at sampling point N1 and the previous sampling point N2 of sampling point N1, and di N1 2 、di N5 2 are respectively the difference in the first sum of squares between sampling point N1 and sampling point N5, and Δdi N1 2 is the sudden change in current at sampling point N1. Sampling point N5 is before sampling point N1 and is separated from sampling point N1 by a cycle. The starting module 33 is configured to determine whether a short - circuit fault occurs in the target interval according to the sudden change in current at each sampling point and a preset first short - circuit determination rule, and start the protection device corresponding to the target interval when a short - circuit fault occurs in the target interval.

[0123] In one embodiment, the starting module 33 is further configured to determine whether the sudden changes in current at sampling point N1, sampling point N2, and the previous sampling point N3 of sampling point N2 satisfy the first short - circuit determination rule, where the first short - circuit determination rule is expressed as:

[0124] Δdi N3 2 >(k1*I set ) 2 ;

[0125] Δdi N2 2 +Δdi N3 2 >(k2*I set ) 2 ;

[0126] Δdi N1 2 +Δdi N2 2 +Δdi N3 2 >(k3*Iset ) 2 ;

[0127] wherein, I set is the starting threshold current value of a preset protection device, and k1, k2, and k3 are respectively a preset first weight coefficient, a second weight coefficient, and a third weight coefficient; when the current mutation amounts at sampling point N1, sampling point N2, and sampling point N3 satisfy the first short - circuit determination rule, it is determined that a short - circuit fault occurs in the target interval; when the current mutation amounts at sampling point N1, sampling point N2, and sampling point N3 do not satisfy the first short - circuit determination rule, it is determined that no short - circuit fault occurs in the target interval.

[0128] In one embodiment, the first weight coefficient is less than the second weight coefficient, and the second weight coefficient is less than the third weight coefficient.

[0129] In one embodiment, the acquisition module 30 is further configured to acquire the three - phase voltages and the zero - sequence voltage at multiple consecutive sampling points of the target interval in the first cycle and the second cycle; the first calculation module 31 is further configured to calculate the second sum of squares of the three - phase voltages and the zero - sequence voltage at each sampling point respectively; the second calculation module 32 is further configured to calculate the voltage mutation amount at each sampling point based on the second sum of squares at each sampling point according to the following mathematical expression:

[0130] Δdu N1 2 = du N1 2 - du N5 2 ;

[0131] du N1 2 = |u N1 2 - u N2 2 |;

[0132] wherein, u N1 2 , u N2 2 are respectively the second sum of squares at sampling point N1 and sampling point N2, du N1 2 , du N5 2 are respectively the differences of the second sum of squares at sampling point N1 and sampling point N5, and Δdu N1 2 is the voltage mutation amount at sampling point N1; the starting module 33 is further configured to determine whether a short - circuit fault occurs in the target interval according to the voltage mutation amount at each sampling point and a preset second short - circuit determination rule.

[0133] In one embodiment, the startup module 33 is further configured to determine whether the voltage mutation amounts at sampling point N1, sampling point N2, and the previous sampling point N3 of sampling point N2 satisfy the second short-circuit determination rule, where the second short-circuit determination rule is expressed as:

[0134] Δdu N3 2 >(k4*U set ) 2 ;

[0135] Δdu n2 2 +Δdu N3 2 >(k5*U set ) 2 ;

[0136] Δdu N1 2 +Δdu N2 2 +Δdu N3 2 >(k6*U set ) 2 ;

[0137] where U set is the preset startup threshold voltage value of the protection device, and k4, k5, and k6 are the preset fourth weight coefficient, fifth weight coefficient, and sixth weight coefficient respectively; when the voltage mutation amounts at sampling point N1, sampling point N2, and sampling point N3 satisfy the second short-circuit determination rule, it is determined that a short-circuit fault occurs in the target interval; when the voltage mutation amounts at sampling point N1, sampling point N2, and sampling point N3 do not satisfy the second short-circuit determination rule, it is determined that no short-circuit fault occurs in the target interval.

[0138] In one embodiment, the fourth weight coefficient is less than the fifth weight coefficient, and the fifth weight coefficient is less than the sixth weight coefficient.

[0139] In one embodiment, the period of one cycle is 20 ms.

[0140] It should be noted that for the information interaction, execution process, etc. between the above-mentioned devices / units, since they are based on the same concept as the method embodiment of the present application, for their specific functions and the technical effects brought, reference can be specifically made to the method embodiment part, and details are not described herein again.

[0141] Those skilled in the art can clearly understand that, for the convenience and conciseness of description, only the division of the above functional units and modules is used as an example for illustration. 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 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 the functional units and modules are only for the convenience of mutual distinction and do not limit the protection scope of the present 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.

[0142] Figure 4 is a schematic structural diagram of a terminal device according to an embodiment of the present application. As Figure 4 shown, the terminal device 4 includes: at least one processor 40 ( Figure 4 only one is shown in the figure), a processor, a memory 41, and a computer program 42 stored in the memory 41 and executable on at least one processor 40. When the processor 40 executes the computer program 42, the steps in the foregoing method embodiments for starting any of the above protection devices are implemented.

[0143] The terminal device 4 can be a computing device such as a desktop computer, a notebook, a palm computer, and a cloud server. The terminal device 4 may include, but is not limited to, the processor 40 and the memory 41. Those skilled in the art can understand that Figure 4 merely examples of the terminal device 4 do not constitute a limitation on the terminal device 4, and may include more or fewer components than shown in the figure, or combine some components, or different components. For example, it may also include input / output devices, network access devices, etc.

[0144] The processor 40 may be a central processing unit (CPU), and the processor 40 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.

[0145] The memory 41 may be an internal storage unit of the terminal device 4 in some embodiments, such as the hard disk or memory of the terminal device 4. The memory 41 may also be an external storage device of the terminal device 4 in other embodiments, such as a plug-in hard disk equipped on the terminal device 4, a Smart Media Card (SMC), a Secure Digital (SD) card, a Flash Card, etc. In other embodiments, the memory 41 may also include both the internal storage unit and the external storage device of the terminal device 4. The memory 41 is used to store an operating system, application programs, a BootLoader, data, and other programs, such as the program code of the computer program 42. The memory 41 may also be used to temporarily store the data that has been output or will be output.

[0146] The embodiment of the present application also provides a computer-readable storage medium, which stores a computer program. When the computer program is executed by a processor, the steps in the embodiment of the startup method of the above-mentioned various protection devices can be implemented.

[0147] The embodiment of the present application provides a computer program product. When the computer program product runs on a mobile terminal, the mobile terminal can implement the steps in the embodiment of the startup method of the above-mentioned various protection devices when executed.

[0148] To implement all or part of the processes in the above-mentioned embodiment methods of the present application, it can be completed by a computer program instructing relevant hardware. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, the steps in 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 the form of source code, object code, executable file, or some intermediate form, etc. The computer-readable medium can at least include: any entity or device capable of carrying the computer program code to the terminal device, a recording medium, a computer memory, a read-only memory (ROM), a random access memory (RAM), an electrical 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 disc, etc.

[0149] In the above embodiments, the descriptions of the various embodiments have their own focuses. For the parts not detailed or recorded in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0150] Those of ordinary skill in the art can realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be implemented by electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are executed in a hardware or software manner depends on the specific application and design constraints of the technical solution. A professional technician can use different methods for each specific application to implement the described functions, but such implementation should not be considered to exceed the scope of this application.

[0151] In the embodiments provided in this application, it should be understood that the disclosed device / network device and method can be implemented in other ways. For example, the device / network device embodiments described above are merely illustrative. For example, the division of modules or units is only a logical function division. In actual implementation, there may 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 coupling or direct coupling or communication connection between each other can be through some interfaces. The indirect coupling or communication connection of the device or unit can be in an electrical, mechanical or other form.

[0152] The units described as separate components may or may not be physically separated. The components displayed as units may or may not be physical units, that is, they can be located in one place, or can be 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.

[0153] The above embodiments are only used to illustrate the technical solutions of this application, rather than to limit it; although this application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements for some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be included in the protection scope of this application.

Claims

1. A method for starting a protection device, characterized in that: include: Acquire the three-phase current and the zero-sequence current of the target interval at a plurality of consecutive sampling points of the first cycle and a plurality of consecutive sampling points of the second cycle, wherein the second cycle is before the first cycle and is separated from the first cycle by a cycle period; respectively calculating the first square sum of the three-phase current and the zero-sequence current at each sampling point; Based on the first square sum at each sampling point, the current mutation amount at each sampling point is calculated according to the following mathematical expression: Δdi N1 2 =di N1 2 -di N5 2 ; of N1 2 =|i N1 2 -i N2 2 |; Among them, i N1 2 、i N2 2 are respectively the first square sum at the sampling point N1 and the sampling point N2 before the sampling point N1, di N1 2 、di N5 2 are the first square sum difference at the sampling point N1 and the sampling point N5, Δdi N1 2 is the current mutation amount at the sampling point N1, the sampling point N5 is before the sampling point N1, and is separated from the sampling point N1 by the period of one cycle; According to the current mutation amount at each sampling point and a preset first short-circuit determination rule, it is determined whether a short-circuit fault occurs in the target interval, and when the short-circuit fault occurs in the target interval, a protection device corresponding to the target interval is started.

2. The method according to claim 1, characterized in that Determining whether a short circuit fault occurs in the target interval according to the current mutation amount at each sampling point and a preset first short circuit determination rule includes: Determine whether the current mutation amounts at the sampling point N1, the sampling point N2, and the sampling point N3 before the sampling point N2 meet the first short circuit determination rule, wherein the first short circuit determination rule is expressed as: Δdi N3 2 >(k1*I set ) 2 ; Δdi N2 2 +Δdi N3 2 >(k2*I set ) 2 ; Δdi N1 2 +Δdi N2 2 +Δdi N3 2 >(k3*I set ) 2 ; Among them, I set is a preset starting threshold current value of the protection device, k1, k2 and k3 are respectively a preset first weight coefficient, a second weight coefficient and a third weight coefficient; When the current mutation amounts at the sampling point N1, the sampling point N2, and the sampling point N3 satisfy the first short-circuit determination rule, determining that the short-circuit fault occurs in the target interval; When the current mutation amounts at the sampling point N1 , the sampling point N2 , and the sampling point N3 do not satisfy the first short-circuit determination rule, it is determined that the short-circuit fault does not occur in the target interval.

3. The method according to claim 2, characterized in that The first weight coefficient is smaller than the second weight coefficient, and the second weight coefficient is smaller than the third weight coefficient.

4. The method according to any one of claims 1 to 3, characterized in that After determining whether a short circuit fault occurs in the target interval according to the current mutation amount at each sampling point and a preset first short circuit determination rule, the method further includes: Acquire the three-phase voltage and the zero-sequence voltage of the target interval at the plurality of continuous sampling points of the first cycle and the second cycle; respectively calculating the second square sum of the three-phase voltage and the zero-sequence voltage at each sampling point; Based on the second square sum at each sampling point, the voltage mutation amount at each sampling point is calculated according to the following mathematical expression: Δyou N1 2 =you N1 2 -you N5 2 ; you N1 2 =|u N1 2 -u N2 2 |; Among them, u N1 2 、u N2 2 are the second square sums at the sampling point N1 and the sampling point N2 respectively, du N1 2 、 N5 2 are the second square sum difference at the sampling point N1 and the sampling point N5, Δdu n1 2 is the voltage mutation amount at the sampling point N1; Whether the short circuit fault occurs in the target interval is determined according to the voltage mutation amount at each sampling point and a preset second short circuit determination rule.

5. The method according to claim 4, characterized in that Determining whether the short circuit fault occurs in the target interval according to the voltage mutation amount at each sampling point and a preset second short circuit determination rule includes: It is determined whether the voltage mutation amounts at the sampling point N1, the sampling point N2, and the sampling point N3 before the sampling point N2 meet the second short circuit determination rule, wherein the second short circuit determination rule is expressed as: Δdu N3 2 >(k4*U set ) 2 ; Δdu N2 2 +Δdu N3 2 >(k5*U set ) 2 ; Δdu n1 2 +Δdu N2 2 +Δdu N3 2 >(k6*U set ) 2 ; Among them, U set is a preset starting threshold voltage value of the protection device, k4, k5 and k6 are respectively a preset fourth weight coefficient, a fifth weight coefficient and a sixth weight coefficient; When the voltage mutation amounts at the sampling point N1, the sampling point N2, and the sampling point N3 satisfy the second short-circuit determination rule, determining that the short-circuit fault occurs in the target interval; When the voltage mutation amounts at the sampling point N1 , the sampling point N2 , and the sampling point N3 do not satisfy the second short-circuit determination rule, it is determined that the short-circuit fault does not occur in the target interval.

6. The method according to claim 5, characterized in that The fourth weight coefficient is smaller than the fifth weight coefficient, and the fifth weight coefficient is smaller than the sixth weight coefficient.

7. The method according to any one of claims 1 to 3, characterized in that The period of one cycle is 20ms.

8. A starting device for a protection device, characterized in that: include: An acquisition module, used for acquiring the three-phase current and the zero-sequence current of the target interval at a plurality of consecutive sampling points of a first cycle and a plurality of consecutive sampling points of a second cycle, wherein the second cycle is before the first cycle and is separated from the first cycle by a cycle period; A first calculation module, used for respectively calculating the first square sum of the three-phase current and the zero-sequence current at each sampling point; The second calculation module is used to calculate the current mutation amount at each sampling point based on the first square sum at each sampling point according to the following mathematical expression: Δdi N1 2 =di N1 2 -di N5 2 ; of N1 2 =|i N1 2 -i N2 2 |; Among them, i N1 2 、i N2 2 are respectively the first square sum at the sampling point N1 and the sampling point N2 before the sampling point N1, di N1 2 、di N5 2 are the first square sum difference at the sampling point N1 and the sampling point N5, Δdi N1 2 is the current mutation amount at the sampling point N1, the sampling point N5 is before the sampling point N1, and is separated from the sampling point N1 by the period of one cycle; A starting module is used to determine whether a short circuit fault occurs in the target interval according to the current mutation amount at each sampling point and a preset first short circuit judgment rule, and to start a protection device corresponding to the target interval when the short circuit fault occurs in the target interval.

9. A terminal device, comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, characterized in that: When the processor executes the computer program, the method for starting the protection device according to any one of claims 1 to 7 is implemented.

10. A computer program product, characterized in that The invention comprises a computer program, and when the computer program is executed, the method for starting the protection device according to any one of claims 1 to 7 is executed.

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