Method for determining protection setting value of distribution line considering change of distribution network structure

Abstract

The application provides a method for determining power distribution line protection setting value considering power distribution network framework structure change. The method comprises the following steps: obtaining power distribution line parameters and zero sequence overcurrent protection setting value of a power distribution network, and determining maximum ground zero sequence capacitance value according to the power distribution line parameters and the zero sequence overcurrent protection setting value; obtaining multiple topological structures of the power distribution line, determining zero sequence capacitance values corresponding to each topological structure, sorting the multiple zero sequence capacitance values of the power distribution line according to a predetermined order, and comparing each zero sequence capacitance value with the maximum ground zero sequence capacitance value according to the predetermined order; in the case that the current zero sequence capacitance value is smaller than the maximum ground zero sequence capacitance value, determining that the power distribution line operates under the topological structure corresponding to the first zero sequence capacitance value to the topological structure corresponding to the current zero sequence capacitance value, and determining that the maximum ground zero sequence capacitance value is the protection setting value of the power distribution line. Through the application, the problem that it is difficult to determine the line protection setting value of different power distribution network structures is solved.

Description

Technical Field

[0001] This application relates to the field of power system relay protection technology, and more specifically, to a method for determining the protection settings of distribution lines considering changes in the distribution network structure, a device for determining the protection settings of distribution lines considering changes in the distribution network structure, a computer-readable storage medium, and an electronic device. Background Technology

[0002] Distribution network lines are the part of the power grid that directly distributes electrical energy to users, and their power supply reliability directly affects users' electricity experience. Statistics show that 80% of power outages are caused by distribution network outages, and 40% of these are caused by distribution network faults. Distribution network protection is a crucial means of improving fault handling capabilities. Most distribution networks only configure outgoing switch protection as the main protection for distribution lines. Properly setting switch settings allows for timely tripping of switches when a fault occurs, minimizing the outage area and improving the reliability of the distribution network. However, due to the lack of a unified standard for the setting of outgoing switches in existing distribution network protection systems, most distribution networks use the same zero-sequence overcurrent protection setting for different distribution lines, significantly impacting power supply reliability. Furthermore, with rapid economic development and continuous improvement in urban construction, the structure of distribution networks is becoming increasingly diversified and complex. This makes the existing zero-sequence overcurrent protection setting of outgoing switches in some distribution network topologies inapplicable, leading to maloperation of outgoing switches and greatly reducing the reliability of the distribution network's power supply.

[0003] Therefore, a method for determining the protection settings of distribution lines that can adapt to changes in complex distribution network structures is needed. Summary of the Invention

[0004] The main objective of this application is to provide a method for determining the protection settings of distribution lines considering changes in the distribution network structure, a device for determining the protection settings of distribution lines considering changes in the distribution network structure, a computer-readable storage medium, and an electronic device, so as to at least solve the problem in the prior art that it is difficult to determine the protection settings of lines with different distribution network structures.

[0005] To achieve the above objectives, according to one aspect of this application, a method for determining the protection settings of distribution lines considering changes in the distribution network structure is provided, comprising: acquiring distribution line parameters and zero-sequence overcurrent protection settings of the distribution network; determining a maximum zero-sequence capacitance value to ground based on the distribution line parameters and the zero-sequence overcurrent protection settings; wherein the distribution network includes at least one distribution line, the distribution line includes multiple topologies, and the distribution line parameters include at least a zero-sequence voltage; acquiring multiple topologies of the distribution line; determining the zero-sequence capacitance value corresponding to each topology; and arranging the multiple zero-sequence capacitance values ​​of the distribution line according to a predefined... The zero-sequence capacitance values ​​are sorted in a predetermined order, and each zero-sequence capacitance value is compared with the maximum zero-sequence capacitance value to ground according to the predetermined order; the first determination step is: if the current zero-sequence capacitance value is less than the maximum zero-sequence capacitance value to ground, the power distribution line is determined to operate under the topology corresponding to the first zero-sequence capacitance value to the topology corresponding to the current zero-sequence capacitance value, and the maximum zero-sequence capacitance value to ground is determined to be the protection setting value of the power distribution line, wherein the first zero-sequence capacitance value is the first zero-sequence capacitance value after being arranged in the predetermined order, and the current zero-sequence capacitance value is the current zero-sequence capacitance value after being sorted in the predetermined order.

[0006] Optionally, determining the maximum zero-sequence capacitance to ground based on the power distribution line parameters and the zero-sequence overcurrent protection setting includes: determining the maximum zero-sequence capacitance to ground based on the power distribution line parameters and the zero-sequence overcurrent protection setting using a formula. Determine the maximum zero-sequence capacitance to ground, where C set.i This represents the i-th maximum zero-sequence capacitance value to ground. K represents the i-th zero-sequence overcurrent protection setting. rel Represents the reliability coefficient. The zero-sequence voltage of the busbar is given under the condition of a metallic ground fault, where j represents the imaginary part coefficient and ω represents the angular frequency.

[0007] Optionally, determining the zero-sequence capacitance value corresponding to each of the topologies includes: according to the formula Determine the zero-sequence capacitance value corresponding to each of the topologies, where C 0Σi C represents the zero-sequence capacitance value. 0i C represents the zero-sequence capacitance value of the main line of the i-th distribution line. 0i_j This represents the zero-sequence capacitance value of the j-th (j=1,2,…,m) branch line of the i-th (i=1,2,…,n) distribution line.

[0008] Optionally, determining the maximum zero-sequence capacitance to ground as the protection setting of the distribution line includes: if the topology corresponding to the current zero-sequence capacitance value is the last topology of the distribution line, determining the maximum zero-sequence capacitance to ground as the protection setting of the distribution line; if the topology corresponding to the current zero-sequence capacitance value is not the last topology of the distribution line, continuing to execute the first determination step at least once until the topology corresponding to the current zero-sequence capacitance value is the last topology of the distribution line, and determining the maximum zero-sequence capacitance to ground as the protection setting of the distribution line.

[0009] Optionally, the method further includes: a second determining step: if the current zero-sequence capacitance value is greater than or equal to the maximum zero-sequence capacitance value to ground, determining that the power distribution line operates under the topology from the topology corresponding to the first zero-sequence capacitance value to the topology corresponding to the previous zero-sequence capacitance value of the current zero-sequence capacitance value, and determining that the current zero-sequence capacitance value is the protection setting value of the power distribution line, wherein the previous zero-sequence capacitance value is the previous zero-sequence capacitance value adjacent to the current zero-sequence capacitance value after being arranged in the predetermined order.

[0010] Optionally, after determining that the power distribution line operates under the topology corresponding to the first zero-sequence capacitance value to the topology corresponding to the previous zero-sequence capacitance value, the method further includes: determining that the power distribution line will malfunction when operating under the topology corresponding to the current zero-sequence capacitance value and the topology corresponding to the zero-sequence capacitance value after the current zero-sequence capacitance value.

[0011] Optionally, sorting the plurality of zero-sequence capacitance values ​​of the power distribution line in a predetermined order, and comparing each zero-sequence capacitance value with the maximum zero-sequence capacitance value to ground in the predetermined order, includes: sorting the plurality of zero-sequence capacitance values ​​of the power distribution line in ascending order; and comparing each zero-sequence capacitance value with the maximum zero-sequence capacitance value to ground in the ascending order.

[0012] According to another aspect of this application, a device for determining the protection settings of distribution lines considering changes in the distribution network structure is provided, comprising: a first determining unit, configured to acquire distribution line parameters and zero-sequence overcurrent protection settings of the distribution network, and determine a maximum zero-sequence capacitance value to ground based on the distribution line parameters and the zero-sequence overcurrent protection settings, wherein the distribution network includes at least one distribution line, the distribution line includes multiple topologies, and the distribution line parameters include at least a zero-sequence voltage; and a comparison unit, configured to acquire multiple topologies of the distribution line, determine the zero-sequence capacitance value corresponding to each topology, and sort the multiple zero-sequence capacitance values ​​of the distribution line according to a predetermined order. The system first sorts the zero-sequence capacitance values ​​and compares each zero-sequence capacitance value with the maximum zero-sequence capacitance value to ground according to the predetermined order; the second determining unit is used to perform the first determining step: when the current zero-sequence capacitance value is less than the maximum zero-sequence capacitance value to ground, it determines that the power distribution line operates under the topology corresponding to the first zero-sequence capacitance value to the topology corresponding to the current zero-sequence capacitance value, and determines that the maximum zero-sequence capacitance value to ground is the protection setting value of the power distribution line, wherein the first zero-sequence capacitance value is the first zero-sequence capacitance value after being arranged according to the predetermined order, and the current zero-sequence capacitance value is the current zero-sequence capacitance value after being sorted according to the predetermined order.

[0013] According to another aspect of this application, a computer-readable storage medium is provided, the computer-readable storage medium including a stored program, wherein, when the program is executed, it controls the device where the computer-readable storage medium is located to execute any of the methods for determining the protection settings of distribution lines considering changes in the distribution network structure.

[0014] According to another aspect of this application, an electronic device is provided, comprising: one or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including methods for performing any of the methods described for determining distribution line protection settings considering changes in the distribution network structure.

[0015] By applying the technical solution of this application, the power distribution line parameters and zero-sequence overcurrent protection settings of the power distribution network are obtained. The maximum zero-sequence capacitance value to ground is determined based on the power distribution line parameters and the zero-sequence overcurrent protection settings. Multiple topologies of the power distribution line are obtained, and the zero-sequence capacitance value corresponding to each topology is determined. The multiple zero-sequence capacitance values ​​of the power distribution line are sorted in a predetermined order, and each zero-sequence capacitance value is compared with the maximum zero-sequence capacitance value to ground in a predetermined order. Then, if the current zero-sequence capacitance value is less than the maximum zero-sequence capacitance value to ground, the power distribution line is determined to operate under the topology from the first zero-sequence capacitance value to the current zero-sequence capacitance value, and the maximum zero-sequence capacitance value to ground is determined as the protection setting of the power distribution line. In contrast to existing technologies, the zero-sequence overcurrent protection settings of distribution network line outgoing switches are sometimes inapplicable to certain distribution network topologies, leading to maloperation of the outgoing switches. This application addresses this issue by determining the protection settings for distribution lines based on various distribution network topologies and the zero-sequence overcurrent protection settings. This makes the application suitable for distribution networks with complex topologies, thus improving network reliability. Therefore, it solves the problem of determining line protection settings for different distribution network structures in existing technologies. Attached Figure Description

[0016] The accompanying drawings, which form part of this application, are used to provide a further understanding of this application. The illustrative embodiments and descriptions of this application are used to explain this application and do not constitute an undue limitation of this application. In the drawings:

[0017] Figure 1 This illustration shows a hardware block diagram of a mobile terminal that performs a method for determining the protection settings of distribution lines considering changes in the distribution network structure, according to an embodiment of this application.

[0018] Figure 2 A schematic flowchart of a method for determining the protection settings of distribution lines considering changes in the distribution network structure, provided by an embodiment of this application, is shown.

[0019] Figure 3 The illustration shows a flowchart of a specific method for determining the protection settings of distribution lines that takes into account changes in the distribution network structure, according to an embodiment of this application.

[0020] Figure 4 This illustration shows a schematic diagram of the first topology of a 10kV "double-chain" low-resistance grounded distribution network model provided by an embodiment of this application;

[0021] Figure 5 This illustration shows a second topology diagram of a 10kV "double-chain" low-resistance grounded distribution network model provided by an embodiment of this application;

[0022] Figure 6This illustration shows a third topology diagram of a 10kV "double-chain" low-resistance grounded distribution network model provided by an embodiment of this application;

[0023] Figure 7 This illustration shows a fourth topology diagram of a 10kV "double-chain" low-resistance grounded distribution network model provided by an embodiment of this application;

[0024] Figure 8 This illustration shows a schematic diagram of the relationship between the zero-sequence current and the zero-sequence overcurrent protection setting value on the distribution line L2 when a metallic single-phase ground fault occurs at point f1 under the topology of the four operating modes of the distribution line L2 provided in Table 7, according to an embodiment of this application.

[0025] Figure 9 This application illustrates a zero-sequence network diagram of a single-phase grounding fault in a 10kV "double-chain" low-resistance grounding system provided by an embodiment of this application.

[0026] Figure 10 A structural block diagram of a device for determining the protection settings of distribution lines that takes into account changes in the distribution network structure, according to an embodiment of this application, is shown.

[0027] The above figures include the following reference numerals:

[0028] 102. Processor; 104. Memory; 106. Transmission device; 108. Input / output device. Detailed Implementation

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present application, and not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of the present application.

[0031] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this application described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0032] For ease of description, the following explains some of the nouns or terms used in the embodiments of this application:

[0033] Zero-sequence overcurrent protection settings: Zero-sequence overcurrent protection settings are used in power systems to detect and protect against zero-sequence faults. When a zero-sequence fault occurs in a power system, it leads to an increase in zero-sequence current. At this time, the zero-sequence overcurrent protection setting comes into play. It detects and measures the zero-sequence current in the system and triggers protection action when it reaches the set value, thereby preventing further damage to the power system. The setting of the zero-sequence overcurrent protection setting needs to be determined based on the specific power system conditions and requirements to ensure that the system can trigger protection action in a timely and accurate manner.

[0034] Zero-sequence capacitance to ground: This refers to a capacitor connected to ground in a power system to eliminate or reduce zero-sequence voltage to ground. Zero-sequence capacitance to ground is commonly used to improve system stability and reduce the impact of zero-sequence voltage to ground, playing a particularly important role under unbalanced loads or fault conditions. By connecting a zero-sequence capacitance to ground, the instability of zero-sequence voltage to ground can be effectively reduced, thereby improving the reliability and safety of the system.

[0035] Zero-sequence capacitance refers to the capacitance value generated by a capacitor connected to ground in a three-phase power system. It is used to limit or eliminate zero-sequence current in the system, thereby protecting equipment and the system from zero-sequence faults. Zero-sequence capacitance values ​​are commonly used in the design and calculation of system protection devices and equipment.

[0036] As described in the background section, the structure of existing power distribution networks is becoming increasingly diversified and complex. This makes the zero-sequence overcurrent protection settings of existing power distribution line outgoing switches inapplicable to certain power distribution line topologies, leading to maloperation of the outgoing switches and reducing the reliability of the power supply. To address the difficulty in determining the protection settings for different power distribution network structures, embodiments of this application provide a method for determining the protection settings of power distribution lines that consider changes in the power distribution network structure, a device for determining the protection settings of power distribution lines that consider changes in the power distribution network structure, a computer-readable storage medium, and an electronic device.

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0038] The methods and embodiments provided in this application can be executed on a mobile terminal, computer terminal, or similar computing device. Taking running on a mobile terminal as an example, Figure 1 This is a hardware structure block diagram of a mobile terminal for a method of determining the protection settings of power distribution lines considering changes in the power distribution network structure, according to an embodiment of the present invention. Figure 1 As shown, a mobile terminal may include one or more ( Figure 1 Only one is shown in the diagram. A processor 102 (which may include, but is not limited to, a microprocessor MCU or a programmable logic device FPGA, etc.) and a memory 104 for storing data are also shown. The mobile terminal may further include a transmission device 106 for communication functions and an input / output device 108. Those skilled in the art will understand that... Figure 1 The structure shown is for illustrative purposes only and does not limit the structure of the mobile terminal described above. For example, the mobile terminal may also include components that are more... Figure 1 The more or fewer components shown, or having the same Figure 1 The different configurations shown.

[0039] The memory 104 can be used to store computer programs, such as application software programs and modules, like the computer program corresponding to the method for determining the protection settings of distribution lines considering changes in the distribution network structure in this embodiment of the invention. The processor 102 executes various functional applications and data processing by running the computer program stored in the memory 104, thereby implementing the above-described method. The memory 104 may include high-speed random access memory and may also include non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some instances, the memory 104 may further include memory remotely located relative to the processor 102, and these remote memories can be connected to the mobile terminal via a network. Examples of the above-described networks include, but are not limited to, the Internet, corporate intranets, local area networks, mobile communication networks, and combinations thereof. The transmission device 106 is used to receive or send data via a network. Specific examples of the above-described networks may include wireless networks provided by the mobile terminal's communication provider. In one example, the transmission device 106 includes a network interface controller (NIC), which can be connected to other network devices via a base station to communicate with the Internet. In one example, the transmission device 106 may be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0040] This embodiment provides a method for determining the protection settings of distribution lines considering changes in the distribution network structure, which runs on a mobile terminal, computer terminal, or similar computing device. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Also, although the logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in a different order than that shown here.

[0041] Figure 2 This is a flowchart illustrating a method for determining the protection settings of distribution lines considering changes in the distribution network structure, according to an embodiment of this application. Figure 2 As shown, the method includes the following steps:

[0042] Step S201: Obtain the power distribution line parameters and zero-sequence overcurrent protection setting of the power distribution network, and determine the maximum zero-sequence capacitance value to ground based on the power distribution line parameters and the zero-sequence overcurrent protection setting. The power distribution network includes at least one power distribution line, the power distribution line includes multiple topologies, and the power distribution line parameters include at least zero-sequence voltage.

[0043] Specifically, when a zero-sequence fault occurs in the power system, it leads to an increase in zero-sequence current. At this time, the zero-sequence overcurrent protection setting comes into play. It detects and measures the zero-sequence current in the system and triggers protection action when it reaches a set value, thereby preventing further damage to the power system. The setting of the zero-sequence overcurrent protection setting needs to be determined based on the specific power system conditions and requirements to ensure that the system can trigger protection action in a timely and accurate manner. Therefore, by collecting the distribution line topology (in step S202), distribution line parameters, and the zero-sequence overcurrent protection setting, the maximum zero-sequence capacitance to ground of the distribution line to which the protection setting applies is derived in reverse. The possible topologies of the distribution line are determined, and the total zero-sequence capacitance to ground of the distribution line topology under different operating modes is calculated. This is compared with the maximum zero-sequence capacitance to ground of the distribution line to which the zero-sequence overcurrent protection setting applies, thereby evaluating whether the zero-sequence overcurrent protection setting is applicable to the distribution line under this operating mode, limiting the operating modes where the protection setting may malfunction, and reducing the problem of maloperation of the zero-sequence overcurrent protection at the line outlet. A power distribution network typically includes multiple power distribution lines, and each power distribution line includes various topologies.

[0044] Step S202: Obtain multiple topologies of the power distribution line, determine the zero-sequence capacitance value corresponding to each topology, sort the multiple zero-sequence capacitance values ​​of the power distribution line in a predetermined order, and compare each zero-sequence capacitance value with the maximum zero-sequence capacitance value to ground in the predetermined order.

[0045] Specifically, since power distribution lines may operate in various different modes, and different modes have different topologies, it is necessary to obtain the topology of the power distribution lines under different operating modes, determine the zero-sequence capacitance values ​​under different topologies, and then sort them. The predetermined order can be ascending order (from small to large) or descending order (from large to small).

[0046] Step S203, First determination step: When the current zero-sequence capacitance value is less than the maximum zero-sequence capacitance value to ground, determine that the power distribution line operates under the topology corresponding to the first zero-sequence capacitance value to the topology corresponding to the current zero-sequence capacitance value, and determine that the maximum zero-sequence capacitance value to ground is the protection setting value of the power distribution line, wherein the first zero-sequence capacitance value is the first zero-sequence capacitance value after being arranged in the predetermined order, and the current zero-sequence capacitance value is the current zero-sequence capacitance value after being sorted in the predetermined order.

[0047] Specifically, the current zero-sequence capacitance value is assumed to be the k-th zero-sequence capacitance value arranged in a predetermined order, and is represented as follows: The maximum zero-sequence capacitance to ground is expressed as C. set.i Then in In this case, it is determined that the aforementioned zero-sequence overcurrent protection setting of the distribution line is applicable under the topology corresponding to the k-th operating mode, and it is determined whether the k-th topology is the last topology of distribution line i. If not, then k = k + 1, and the comparison step continues; if so, then the zero-sequence overcurrent protection setting of the distribution line is applicable under the 1st (topology corresponding to the first zero-sequence capacitance value) to the k-th (topology corresponding to the current zero-sequence capacitance value) operating modes, that is, it operates under the topology corresponding to the first zero-sequence capacitance value to the topology corresponding to the current zero-sequence capacitance value. In this case, the maximum zero-sequence capacitance value to ground can be considered as the protection setting of the distribution line.

[0048] This embodiment obtains the distribution line parameters and zero-sequence overcurrent protection settings of the distribution network. Based on these parameters, the maximum zero-sequence capacitance to ground is determined. Multiple distribution line topologies are acquired, and the corresponding zero-sequence capacitance value for each topology is determined. These zero-sequence capacitance values ​​are then sorted in a predetermined order, and each value is compared with the maximum zero-sequence capacitance to ground in the same order. If the current zero-sequence capacitance value is less than the maximum zero-sequence capacitance to ground, the distribution line is determined to operate under the topologies corresponding to the first and current zero-sequence capacitance values, and the maximum zero-sequence capacitance to ground is determined as the protection setting for the distribution line. Compared to existing technologies where the zero-sequence overcurrent protection setting of the distribution network line outgoing switches is inapplicable in certain distribution line topologies, leading to maloperation of the outgoing switches, this application can determine the protection setting based on various distribution line topologies and zero-sequence overcurrent protection settings in the distribution network. This is applicable to distribution networks with complex topologies and improves the reliability of the distribution network. Therefore, it can solve the problem of determining the line protection settings for different power distribution network structures in existing technologies.

[0049] In the specific implementation process, determining the maximum zero-sequence capacitance to ground in step S201 above, based on the aforementioned power distribution line parameters and the aforementioned zero-sequence overcurrent protection setting, can be achieved through the following steps: determining the maximum zero-sequence capacitance to ground based on the aforementioned power distribution line parameters and the aforementioned zero-sequence overcurrent protection setting using the formula... Determine the maximum zero-sequence capacitance to ground value mentioned above, where C set.i This represents the i-th maximum zero-sequence capacitance to ground mentioned above. K represents the i-th zero-sequence overcurrent protection setting mentioned above. rel Represents the reliability coefficient. This represents the zero-sequence voltage of the busbar under the condition of a metallic ground fault, where j represents the imaginary part coefficient and ω represents the angular frequency. This method calculates the maximum zero-sequence capacitance to ground using the above formula, thus determining the maximum applicable zero-sequence capacitance to ground for this distribution line, and subsequently making judgments.

[0050] Specifically, zero-sequence capacitance to ground is used to eliminate or reduce zero-sequence voltage to ground in the system. Zero-sequence capacitance to ground is commonly used to improve system stability and reduce the impact of zero-sequence voltage to ground, playing a crucial role, especially under unbalanced loads or fault conditions. By connecting zero-sequence capacitance to ground, the instability of zero-sequence voltage to ground can be effectively reduced, thereby improving the reliability and safety of the system. Therefore, the maximum zero-sequence capacitance to ground value is calculated using the above formula, and by comparing the zero-sequence capacitance value for each topology with the above maximum zero-sequence capacitance value, it is determined whether the distribution line can operate safely. Here, i represents the i-th distribution line, i = 1, 2, ..., n, K. rel The value is generally (1.2 to 1.3), but considering the reliability of protection, we take 1.3.

[0051] To determine the zero-sequence capacitance value for each topology, step S202 of this application determines the zero-sequence capacitance value corresponding to each of the above topologies, which can be achieved through the following steps:

[0052] According to the formula Determine the zero-sequence capacitance value corresponding to each of the above topologies, where C 0Σi C represents the zero-sequence capacitance value mentioned above. 0i C represents the zero-sequence capacitance value of the main line of the i-th distribution line. 0i_j This represents the zero-sequence capacitance value of the j-th (j=1,2,…,m) branch line of the i-th (i=1,2,…,n) of the aforementioned distribution lines. This method determines the zero-sequence capacitance value using the above formula, thus accurately determining the zero-sequence capacitance value for each topology to judge whether that topology meets the requirements for safe operation.

[0053] In practical implementation, zero-sequence capacitance refers to the capacitance value generated by a capacitor connected to ground in a three-phase power system. It is used to limit or eliminate zero-sequence current in the system, thereby protecting equipment and the system from zero-sequence faults. Zero-sequence capacitance values ​​are commonly used in the design and calculation of system protection devices and equipment. Therefore, by calculating the zero-sequence capacitance values ​​corresponding to different topologies and comparing them with the aforementioned maximum zero-sequence capacitance value to ground, it is determined whether the safety operation requirements are met.

[0054] In some embodiments, step S203, which determines the maximum zero-sequence capacitance to ground as the protection setting value of the distribution line, can be implemented through the following steps: if the topology corresponding to the current zero-sequence capacitance value is the last topology of the distribution line, the maximum zero-sequence capacitance to ground is determined as the protection setting value of the distribution line; if the topology corresponding to the current zero-sequence capacitance value is not the last topology of the distribution line, the first determination step is performed at least once until the topology corresponding to the current zero-sequence capacitance value is the last topology of the distribution line, and the maximum zero-sequence capacitance to ground is determined as the protection setting value of the distribution line. This method determines the protection setting value of the distribution line based on all topologies through the above steps, thus accurately determining the protection setting value of each distribution line.

[0055] Specifically, the zero-sequence capacitance to ground of the distribution line topology C under n different operating modes is calculated. 0Σi After arranging in ascending order, the total zero-sequence capacitance to ground for the i-th (i = 1, 2, ..., n) distribution line under the k (k = 1, 2, ..., p) topology is expressed as: Initialize k = 1, compare and C set.i The size, if The zero-sequence overcurrent protection setting of the distribution line is applicable under the k-th operating mode. It is determined whether the k-th topology is the last topology of distribution line i. If not, k = k + 1, and the comparison continues. If so, the first to p-th operating modes of the distribution line are allowed. That is, if it is the last topology, the first to p-th operating modes can all be operated. The zero-sequence capacitance value corresponding to each operating mode meets the safety operation requirements. Therefore, the maximum zero-sequence capacitance value to ground can be considered as the protection setting of the above distribution line.

[0056] In some optional embodiments, the method further includes the following step: a second determination step: when the current zero-sequence capacitance value is greater than or equal to the maximum zero-sequence capacitance value to ground, determining that the power distribution line operates under the topology corresponding to the first zero-sequence capacitance value to the topology corresponding to the previous zero-sequence capacitance value of the current zero-sequence capacitance value, and determining the current zero-sequence capacitance value as the protection setting value of the power distribution line, wherein the previous zero-sequence capacitance value is the previous zero-sequence capacitance value adjacent to the current zero-sequence capacitance value after being arranged in the predetermined order. This method redetermines the protection setting value of the power distribution line when the current zero-sequence capacitance value is greater than or equal to the maximum zero-sequence capacitance value to ground, thus allowing for adjustment of the protection setting value according to different situations.

[0057] In the specific implementation process, if The zero-sequence overcurrent protection setting of the power distribution line will malfunction under the k-th and subsequent operating modes. Therefore, the first to the (k-1)th operating modes (the above topology corresponding to the previous zero-sequence capacitance value) are allowed, while the k-th to p-th operating modes are restricted. In other words, if the current zero-sequence capacitance value is greater than or equal to the above maximum zero-sequence capacitance value to ground, the current zero-sequence capacitance value already meets the maximum limit for safe operation. Therefore, the above current zero-sequence capacitance value is determined as the protection setting of the above power distribution line. That is, the protection setting of the power distribution line cannot exceed the current zero-sequence capacitance value, so as to ensure the safe operation of the power distribution line.

[0058] In some optional embodiments, after determining that the power distribution line operates under the topology corresponding to the first zero-sequence capacitance value to the topology corresponding to the previous zero-sequence capacitance value, the method further includes the step of determining that the power distribution line would malfunction under the topology corresponding to the current zero-sequence capacitance value and the topology corresponding to the zero-sequence capacitance values ​​after the current zero-sequence capacitance value. This method, through the above steps, restricts the operation of operating modes corresponding to topologies that do not meet safe operation requirements, thereby improving the stability and safety of system operation.

[0059] Specifically, as mentioned above, if The zero-sequence overcurrent protection setting of the distribution line will malfunction in the k-th and subsequent operating modes. Therefore, operating modes 1 to k-1 (the topology corresponding to the previous zero-sequence capacitance value) are allowed, while operating modes k to p are restricted. In other words, if... The topology corresponding to the current zero-sequence capacitance value, as well as the topology corresponding to subsequent zero-sequence capacitance values, will malfunction during operation. Of course, the above comparison method applies to a predetermined ascending order. If the predetermined order is descending, the corresponding comparison order and the order in which operation is allowed and restricted are reversed.

[0060] In some optional embodiments, sorting the plurality of zero-sequence capacitance values ​​of the power distribution line in a predetermined order and comparing each of the zero-sequence capacitance values ​​with the maximum zero-sequence capacitance value to ground in the predetermined order includes: sorting the plurality of zero-sequence capacitance values ​​of the power distribution line in ascending order; and comparing each of the zero-sequence capacitance values ​​with the maximum zero-sequence capacitance value to ground in ascending order.

[0061] In the specific implementation process, for the convenience of comparison, the predetermined order is set as an ascending order, that is, the order from small to large. Correspondingly, the comparison order is also from small to large. In the actual application process, the predetermined order can also be a descending order, that is, the order from large to small. Correspondingly, the comparison order and the subsequent order are both opposite to the ascending order.

[0062] In order to enable those skilled in the art to more clearly understand the technical solution of the present application, the implementation process of the method for determining the protection setting value of a distribution line considering the change of the distribution network grid structure of the present application will be described in detail below in conjunction with specific embodiments.

[0063] This embodiment relates to a specific method for determining the protection setting value of a distribution line considering the change of the distribution network grid structure, as Figure 3 shown, including the following steps:

[0064] Step S1: Start;

[0065] Step S2: Collect the topological structure, parameters, and zero-sequence overcurrent protection setting value of the distribution line

[0066] Step S3: Calculate the maximum zero-sequence capacitance value C of the distribution line corresponding to the zero-sequence overcurrent protection setting value set.i ;

[0067] Step S4: Determine the possible operating modes of the distribution line;

[0068] Step S5: Calculate the zero-sequence capacitance C to the ground of the topological structure of the distribution line under different operating modes respectively 0Σi ;

[0069] Step S6: Arrange C 0Σi in ascending order;

[0070] Step S7: Initialize k = 1;

[0071] Step S8: Compare In the case of yes, execute step S9, and in the case of no, execute step S11;

[0072] Step S9: The protection setting value will malfunction;

[0073] Step S10: Allow the operating modes from the 1st to the k - 1st to limit the operating modes from the kth to the pth;

[0074] Step S11: The protection setting value is applicable. Continue to judge k < p? In the case of yes, execute step S12, and in the case of no, execute step S13;

[0075] Step S12: k = k + 1, and continue to execute step S8;

[0076] Step S13: Allow operation in modes 1 through p;

[0077] Step S14: End.

[0078] Figure 4 This is a 10kV distribution network model with a "double-loop" low-resistance grounding system. The neutral point grounding resistance is 6.5Ω. Substation A includes a 220kV generator G, a 220kV / 10.5kV transformer T, and six outgoing lines: L1, L2, L5, L6, L7, and L8, connected to bus A. L1 is connected to bus A via a zero-sequence current transformer (CT), a switch, and a line of length l. 11 =5km of overhead line connects to another busbar, and through l 13 =7km of cable connects to a 10kV / 0.4kV transformer, and through l 14 =8km of cable connects to a 10kV / 0.4kV transformer; L2 is connected via a zero-sequence current transformer, a switch, and a cable of length l 21 A 5km overhead line connects to another busbar, which is connected to another busbar of L1 via a tie switch C. Then, through a switch, a line of length l... 22 =3km of overhead line and tie switch are connected to the intermediate busbar, and the intermediate busbar then passes through a length of l 23 =4km of cable connects to a 10kV / 0.4kV transformer, and through l 24 =6km of cable connects to a 10kV / 0.4kV transformer; L5 is connected to a zero-sequence current transformer, switch, and is l in length. 51 =4km of cable connects to a 10kV / 0.4kV transformer; L6 connects to a zero-sequence current transformer, a switch, and is l in length. 61 A 6km cable connects to the intermediate busbar and passes through the intermediate busbar switch; the cable is 1 km long. 62 =5km and length l 63 =2km of cable connects to a 10kV / 0.4kV transformer respectively; L7 is connected to a zero-sequence current transformer, a switch, and a cable of length l. 71 A 10km cable connects to the intermediate busbar and passes through the intermediate busbar switch; the cable is l long. 72 =5km and length l 73 =5km of cable, each cable connects to a 10kV / 0.4kV transformer; L8 connects to a zero-sequence current transformer, switch, and is l in length. 81A 10km overhead line connects to a 10kV / 0.4kV transformer. Substation B has two outgoing lines, L3 and L4, connected to busbar B. Substation B includes a 220kV generator G, a 220kV / 10.5kV transformer T, and L3 is connected via a zero-sequence current transformer, tie switch D, and a line of length L... 31 =3km of overhead line is connected to another busbar, and connected via a switch. 33 =3km of cable connects to a 10kV / 0.4kV transformer, and through l 32 A 3km cable connects to a 10kV / 0.4kV transformer, with a tie switch A and l between L1 and L3. 12 =2km of overhead line connection; L4 is connected via zero-sequence current transformer, switch and a length of l 41 =5km of overhead line connects to another busbar, and is connected via the busbar l 42 =3km of cable connects to a 10kV / 0.4kV transformer, and through l 43 A 3km cable connects to a 10kV / 0.4kV transformer, with L2 and L4 connected by a tie switch B and l. 22 =3km overhead line connection, Z-type transformer (T) A Connected to bus A, through resistor R N Grounding; Z-type transformer (T) B Connected to bus B, through resistor R N Grounding; points f1, f2, and f3 indicate a metallic single-phase grounding fault. A zero-sequence TV transformer is connected to bus A and bus B respectively. Figure 4 As shown in Table 1:

[0079] Table 1. Line parameters of a 10kV distribution network model with "double-loop" low-resistance grounding.

[0080] parameter R / (Ω / km) <![CDATA[R0 / (Ω / km)]]> L / (mH / km) <![CDATA[L0 / (mH / km)]]> C / (μF / km) <![CDATA[C0 / (μF / km)]]> Overhead line 0.170 0.230 1.200 5.478 0.010 0.008 cable 0.270 2.700 0.255 1.109 0.339 0.280

[0081] Taking a 10kV distribution network in a certain city as an example, the zero-sequence overcurrent protection setting values ​​I for all feeders are as follows: set.IIIi All are 45A. The maximum zero-sequence capacitance to ground of the corresponding distribution line is calculated to be C. set.i =6.361×10 -6 F.

[0082] Based on the collected distribution line topology analysis, taking distribution line L2 as an example, it can be divided into four operating modes, and the zero-sequence capacitance to ground of the line under each of the four topologies can be calculated. The results are arranged in ascending order, as shown in Table 2.

[0083] Table 2. Zero-sequence capacitance values ​​to ground of the lines under different operating topologies.

[0084]

[0085] Type 1 topology: In the initial operating state, both tie switches A and D are in the open state. Its topology is as follows: Figure 4 As shown (see above) Figure 4 (Description).

[0086] The second topology: When substation B is taken out of service for maintenance, to ensure the reliability of the power supply, the distribution automation system restores the power supply to the loads on distribution lines L3 and L4 by closing the tie switches on the distribution lines L1 and L2. Its topology is as follows: Figure 5 As shown (except for the connecting switch being closed, please refer to the above text for the rest). Figure 4 (Description).

[0087] The third topology: Based on the second topology, when the single-phase ground fault point f2 is located on the distribution line L1 at a distance of 6km from the busbar... 12 On this section, the distribution automation system isolates the fault. Subsequently, it closes the tie switch D, connecting the l-type circuit breaker on distribution line L1. 12 Power was restored to the downstream load of the segment, and its topology is as follows: Figure 6 As shown (except for the contact switches A, B, and D, which are in the closed state, please refer to the above text for the rest). Figure 4 (Description).

[0088] Fourth topology: Based on the second topology, when the single-phase ground fault point f3 is located on the distribution line L1 at a distance of 1km from the busbar... 11 On this section, the distribution automation system isolates the fault. Subsequently, the control switches C and D are closed to restore power to all loads on feeder L1, with the topology as follows: Figure 7 As shown (except for the contact switch AD being closed, please refer to the above text for the rest). Figure 4 (Description).

[0089] First, determine the applicability of L2 zero-sequence overcurrent protection for the distribution line under the first topology, as shown in Table 3.

[0090] Table 3 Applicability of Line Zero-Sequence Overcurrent Protection

[0091]

[0092] As shown in Table 3, under the first topology, the zero-sequence capacitance to ground of the distribution line L2 is... satisfy Therefore, under the first topology, the original zero-sequence overcurrent protection setting of the distribution line L2 is fully applicable.

[0093] Since the original zero-sequence overcurrent protection setting is applicable under the first topology, it is necessary to determine the applicability of the zero-sequence overcurrent protection of the distribution line L2 under the second topology, as shown in Table 4.

[0094] Table 4. Applicability of Line Zero-Sequence Overcurrent Protection

[0095]

[0096] As shown in Table 4, under the second topology, the zero-sequence capacitance to ground of distribution line L2 is... satisfy Therefore, the original zero-sequence overcurrent protection settings are still applicable.

[0097] Since the original zero-sequence overcurrent protection setting is applicable under the first two topologies, it is necessary to determine the applicability of the L2 zero-sequence overcurrent protection of the distribution line under the third topology, as shown in Table 5.

[0098] Table 5. Applicability of Line Zero-Sequence Overcurrent Protection

[0099]

[0100] As shown in Table 5, under the third topology, the zero-sequence capacitance to ground of distribution line L2 is... satisfy Therefore, the original zero-sequence overcurrent protection settings are still applicable.

[0101] Since the zero-sequence overcurrent protection setting is applicable to the first three topologies, it is necessary to determine the applicability of the zero-sequence overcurrent protection for the L2 distribution line under the fourth topology, as shown in Table 6.

[0102] Table 6. Application of Line Zero-Sequence Overcurrent Protection

[0103]

[0104] As shown in Table 6, under the fourth topology, the zero-sequence capacitance of feeder L2 to ground is... Therefore, under the fourth topology, the original zero-sequence overcurrent protection setting will malfunction, and the fourth operating mode should be restricted.

[0105] Based on the above analysis, power distribution line L2 should allow the first to third operating modes and restrict the fourth operating mode.

[0106] according to Figure 4The “double-chain ring distribution network” shown is simulated using the simulation software PSCAD / EMTDC. Assuming that the metallic single-phase ground fault point f1 is located on the bus, the magnitude of the zero-sequence current 3I0 flowing through the outlet of distribution line L2 under the four topologies and its protection operation are shown in Table 7.

[0107] Table 7 shows the zero-sequence current and protection operation on line L2 when the fault point is located at f1 under the four operating topologies.

[0108]

[0109] As shown in Table 7, under the first three topologies, the maximum zero-sequence current 3I that may occur at the L2 outlet of the distribution line is... 02 、3I′ 02 and 3I″ 02 All are less than the zero-sequence overcurrent protection setting I set.IIIi Therefore, under the first three topologies, the original zero-sequence overcurrent protection settings of distribution line L2 are applicable, and thus this type of operation can occur during operation. However, under the fourth topology, the maximum zero-sequence current 3I″′ that may occur at the output of feeder L2 is... 02 3I″′ not satisfied 02 <I set.IIIi Therefore, under the fourth topology, the original zero-sequence overcurrent protection setting of distribution line L2 is not applicable, so this operating mode is not allowed or is restricted during operation. Figure 8 Table 7 shows the relationship between the zero-sequence current and the zero-sequence overcurrent protection setting on distribution line L2 under four operating topologies for different modes, when a metallic single-phase ground fault occurs at point f1. It can be seen that 3I 02 、3I′ 02 and 3I″ 02 All are less than the zero-sequence overcurrent protection setting I set.IIIi ,3I″′ 02 Greater than zero-sequence overcurrent protection setting I set.IIIi .

[0110] Figure 9 This is the zero-sequence network diagram of a single-phase ground fault located on the busbar in the low-resistance grounding system of the present invention, C. 01 C 0n C 01_1 C 01_m 3R N With power supply and 3R f The series circuits are connected in parallel, and the currents of each branch are respectively The total voltage of the above branches is Total current is

[0111] This application also provides a device for determining the protection settings of distribution lines considering changes in the distribution network structure. It should be noted that this device can be used to execute the method provided in this application for determining the protection settings of distribution lines considering changes in the distribution network structure. This device is used to implement the above embodiments and preferred embodiments; details already described will not be repeated. As used below, the term "module" can refer to a combination of software and / or hardware that performs a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0112] The following describes the device for determining the protection settings of power distribution lines that takes into account changes in the power distribution network structure, as provided in the embodiments of this application.

[0113] Figure 10 This is a schematic diagram of a device for determining the protection settings of distribution lines, taking into account changes in the distribution network structure, according to an embodiment of this application. Figure 10 As shown, the device includes:

[0114] The first determining unit 10 is used to obtain the distribution line parameters and zero-sequence overcurrent protection setting of the distribution network, and to determine the maximum zero-sequence capacitance value to ground based on the distribution line parameters and the zero-sequence overcurrent protection setting. The distribution network includes at least one distribution line, the distribution line includes multiple topologies, and the distribution line parameters include at least zero-sequence voltage.

[0115] Specifically, when a zero-sequence fault occurs in the power system, it leads to an increase in zero-sequence current. At this time, the zero-sequence overcurrent protection setting comes into play. It detects and measures the zero-sequence current in the system and triggers protection action when it reaches a set value, thereby preventing further damage to the power system. The setting of the zero-sequence overcurrent protection setting needs to be determined based on the specific power system conditions and requirements to ensure that the system can trigger protection action in a timely and accurate manner. Therefore, by collecting the distribution line topology (in step S202), distribution line parameters, and the zero-sequence overcurrent protection setting, the maximum zero-sequence capacitance to ground of the distribution line to which the protection setting applies is derived in reverse. The possible topologies of the distribution line are determined, and the total zero-sequence capacitance to ground of the distribution line topology under different operating modes is calculated. This is compared with the maximum zero-sequence capacitance to ground of the distribution line to which the zero-sequence overcurrent protection setting applies, thereby evaluating whether the zero-sequence overcurrent protection setting is applicable to the distribution line under this operating mode, limiting the operating modes where the protection setting malfunctions, and reducing the problem of maloperation of the line outgoing protection. A power distribution network typically includes multiple power distribution lines, and each power distribution line includes various topologies.

[0116] The comparison unit 20 is used to acquire multiple topologies of the power distribution line, determine the zero-sequence capacitance value corresponding to each topology, sort the multiple zero-sequence capacitance values ​​of the power distribution line in a predetermined order, and compare each zero-sequence capacitance value with the maximum zero-sequence capacitance value to ground in the predetermined order.

[0117] Specifically, since power distribution lines may operate in various different modes, and different modes have different topologies, it is necessary to obtain the topology of the power distribution lines under different operating modes, determine the zero-sequence capacitance values ​​under different topologies, and then sort them. The predetermined order can be ascending order (from small to large) or descending order (from large to small).

[0118] The second determining unit 30 is used to perform the first determining step: when the current zero-sequence capacitance value is less than the maximum zero-sequence capacitance value to ground, it determines that the power distribution line operates under the topology corresponding to the first zero-sequence capacitance value to the topology corresponding to the current zero-sequence capacitance value, and determines that the maximum zero-sequence capacitance value to ground is the protection setting value of the power distribution line, wherein the first zero-sequence capacitance value is the first zero-sequence capacitance value after being arranged in the predetermined order, and the current zero-sequence capacitance value is the current zero-sequence capacitance value after being sorted in the predetermined order.

[0119] Specifically, the current zero-sequence capacitance value is assumed to be the k-th zero-sequence capacitance value arranged in a predetermined order, and is represented as follows: The maximum zero-sequence capacitance to ground is expressed as C. set.i Then in In this case, it is determined that the aforementioned zero-sequence overcurrent protection setting of the distribution line is applicable under the topology corresponding to the k-th operating mode, and it is determined whether the k-th topology is the last topology of distribution line i. If not, then k = k + 1, and the comparison step continues; if so, then the zero-sequence overcurrent protection setting of the distribution line is applicable under the 1st (topology corresponding to the first zero-sequence capacitance value) to the k-th (topology corresponding to the current zero-sequence capacitance value) operating modes, that is, it operates under the topology corresponding to the first zero-sequence capacitance value to the topology corresponding to the current zero-sequence capacitance value. In this case, the maximum zero-sequence capacitance value to ground can be considered as the protection setting of the distribution line.

[0120] This embodiment obtains the distribution line parameters and zero-sequence overcurrent protection settings of the distribution network. Based on these parameters, the maximum zero-sequence capacitance to ground is determined. Multiple distribution line topologies are acquired, and the corresponding zero-sequence capacitance value for each topology is determined. These zero-sequence capacitance values ​​are then sorted in a predetermined order, and each value is compared with the maximum zero-sequence capacitance to ground in the same order. If the current zero-sequence capacitance value is less than the maximum zero-sequence capacitance to ground, the distribution line is determined to operate under the topologies corresponding to the first and current zero-sequence capacitance values, and the maximum zero-sequence capacitance to ground is determined as the protection setting for the distribution line. Compared to existing technologies where the zero-sequence overcurrent protection setting of the distribution network line outgoing switches is inapplicable in certain distribution line topologies, leading to maloperation of the outgoing switches, this application can determine the protection setting based on various distribution line topologies and zero-sequence overcurrent protection settings in the distribution network. This is applicable to distribution networks with complex topologies and improves the reliability of the distribution network. Therefore, it can solve the problem of determining the line protection settings for different power distribution network structures in existing technologies.

[0121] In specific implementation, the first determining unit includes a first determining module, used to determine the distribution line parameters and the zero-sequence overcurrent protection setting using a formula. Determine the maximum zero-sequence capacitance to ground value mentioned above, where C set.i This represents the i-th maximum zero-sequence capacitance to ground mentioned above. K represents the i-th zero-sequence overcurrent protection setting mentioned above. rel Represents the reliability coefficient. This represents the zero-sequence voltage of the busbar under the condition of a metallic ground fault, where j represents the imaginary part coefficient and ω represents the angular frequency. This method calculates the maximum zero-sequence capacitance to ground using the above formula, thus determining the maximum applicable zero-sequence capacitance to ground for this distribution line, and subsequently making judgments.

[0122] Specifically, zero-sequence capacitance to ground is used to eliminate or reduce zero-sequence voltage to ground in the system. Zero-sequence capacitance to ground is commonly used to improve system stability and reduce the impact of zero-sequence voltage to ground, playing a crucial role, especially under unbalanced loads or fault conditions. By connecting zero-sequence capacitance to ground, the instability of zero-sequence voltage to ground can be effectively reduced, thereby improving the reliability and safety of the system. Therefore, the maximum zero-sequence capacitance to ground value is calculated using the above formula, and by comparing the zero-sequence capacitance value for each topology with the above maximum zero-sequence capacitance value, it is determined whether the distribution line can operate safely. Here, i represents the i-th distribution line, i = 1, 2, ..., n, K. rel The value is generally (1.2 to 1.3), but considering the reliability of protection, we take 1.3.

[0123] To determine the zero-sequence capacitance value for each topology, the comparison unit includes a second determining module for determining the value according to the formula... Determine the zero-sequence capacitance value corresponding to each of the above topologies, where C 0Σi C represents the zero-sequence capacitance value mentioned above. 0i C represents the zero-sequence capacitance value of the main line of the i-th distribution line. 0i_j This represents the zero-sequence capacitance value of the j-th (j=1,2,…,m) branch line of the i-th (i=1,2,…,n) of the aforementioned distribution lines. This method determines the zero-sequence capacitance value using the above formula, thus accurately determining the zero-sequence capacitance value for each topology to judge whether that topology meets the requirements for safe operation.

[0124] In practical implementation, zero-sequence capacitance refers to the capacitance value generated by a capacitor connected to ground in a three-phase power system. It is used to limit or eliminate zero-sequence current in the system, thereby protecting equipment and the system from zero-sequence faults. Zero-sequence capacitance values ​​are commonly used in the design and calculation of system protection devices and equipment. Therefore, by calculating the zero-sequence capacitance values ​​corresponding to different topologies and comparing them with the aforementioned maximum zero-sequence capacitance value to ground, it is determined whether the safety operation requirements are met.

[0125] In some embodiments, the second determining unit includes a third determining module and a fourth determining module. The third determining module is used to determine the maximum zero-sequence capacitance to ground value as the protection setting value of the power distribution line when the topology corresponding to the current zero-sequence capacitance value is the last topology of the power distribution line. The fourth determining module is used to continue executing the first determining step at least once when the topology corresponding to the current zero-sequence capacitance value is not the last topology of the power distribution line, until the topology corresponding to the current zero-sequence capacitance value is the last topology of the power distribution line, and then determine the maximum zero-sequence capacitance to ground value as the protection setting value of the power distribution line. This method determines the protection setting value of the power distribution line based on all topologies through the above steps, thus accurately determining the protection setting value of each power distribution line.

[0126] Specifically, the zero-sequence capacitance to ground of the distribution line topology C under n different operating modes is calculated. 0Σi After arranging in ascending order, the total zero-sequence capacitance to ground for the i-th (i = 1, 2, ..., n) distribution line under the k (k = 1, 2, ..., p) topology is expressed as: Initialize k = 1, compare and C set.i The size, if The zero-sequence overcurrent protection setting of the distribution line is applicable under the k-th operating mode. It is determined whether the k-th topology is the last topology of distribution line i. If not, k = k + 1, and the comparison continues. If so, the first to p-th operating modes of the distribution line are allowed. That is, if it is the last topology, the first to p-th operating modes can all be operated. The zero-sequence capacitance value corresponding to each operating mode meets the safety operation requirements. Therefore, the maximum zero-sequence capacitance value to ground can be considered as the protection setting of the above distribution line.

[0127] In some optional embodiments, the method further includes a third determining unit for performing a second determining step: when the current zero-sequence capacitance value is greater than or equal to the maximum zero-sequence capacitance value to ground, determining that the power distribution line operates under the topology from the topology corresponding to the first zero-sequence capacitance value to the topology corresponding to the previous zero-sequence capacitance value of the current zero-sequence capacitance value, and determining the current zero-sequence capacitance value as the protection setting value of the power distribution line, wherein the previous zero-sequence capacitance value is the previous zero-sequence capacitance value adjacent to the current zero-sequence capacitance value after being arranged in the predetermined order. This method redetermines the protection setting value of the power distribution line when the current zero-sequence capacitance value is greater than or equal to the maximum zero-sequence capacitance value to ground, thus allowing for adjustment of the protection setting value according to different situations.

[0128] In the specific implementation process, if The zero-sequence overcurrent protection setting of the power distribution line will malfunction under the k-th and subsequent operating modes. Therefore, the first to the (k-1)th operating modes (the above topology corresponding to the previous zero-sequence capacitance value) are allowed, while the k-th to p-th operating modes are restricted. In other words, if the current zero-sequence capacitance value is greater than or equal to the above maximum zero-sequence capacitance value to ground, the current zero-sequence capacitance value already meets the maximum limit for safe operation. Therefore, the above current zero-sequence capacitance value is determined as the protection setting of the above power distribution line. That is, the protection setting of the power distribution line cannot exceed the current zero-sequence capacitance value, so as to ensure the safe operation of the power distribution line.

[0129] In some optional embodiments, after determining that the power distribution line operates under the topology corresponding to the first zero-sequence capacitance value to the topology corresponding to the previous zero-sequence capacitance value, the method further includes a fourth determining unit, used to determine that the power distribution line will malfunction when operating under the topology corresponding to the current zero-sequence capacitance value and the topology corresponding to the zero-sequence capacitance values ​​after the current zero-sequence capacitance value. This method, through the above steps, restricts the operation of operating modes corresponding to topologies that do not meet safe operation requirements, thereby improving the stability and safety of system operation.

[0130] Specifically, as mentioned above, if The zero-sequence overcurrent protection setting of the distribution line will malfunction in the k-th and subsequent operating modes. Therefore, operating modes 1 to k-1 (the topology corresponding to the previous zero-sequence capacitance value) are allowed, while operating modes k to p are restricted. In other words, if... The topology corresponding to the current zero-sequence capacitance value, as well as the topology corresponding to subsequent zero-sequence capacitance values, will malfunction during operation. Of course, the above comparison method applies to a predetermined ascending order. If the predetermined order is descending, the corresponding comparison order and the order in which operation is allowed and restricted are reversed.

[0131] In some optional implementations, the comparison unit includes a first comparison module and a second comparison module. The first comparison module is used to sort the plurality of zero-sequence capacitance values ​​of the power distribution line in ascending order. The second comparison module is used to compare each of the zero-sequence capacitance values ​​with the maximum zero-sequence capacitance value to ground in ascending order.

[0132] In practice, for ease of comparison, the predetermined order is set to ascending, i.e., from smallest to largest, and correspondingly, the comparison order is also from smallest to largest. In actual applications, the predetermined order can also be descending, i.e., from largest to smallest, in which case the comparison order and subsequent order are the reverse of ascending order.

[0133] The aforementioned device for determining the protection settings of distribution lines considering changes in the distribution network structure includes a processor and a memory. The first determining unit, comparison unit, and second determining unit, etc., are all stored as program units in the memory. The processor executes these program units stored in the memory to achieve the corresponding functions. All of the above modules are located in the same processor; alternatively, the modules may be located in different processors in any combination.

[0134] The processor contains a kernel, which retrieves the corresponding program units from memory. One or more kernels can be configured, and adjusting kernel parameters can solve the problem of determining line protection settings for different power distribution network structures.

[0135] The memory may include non-permanent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, such as read-only memory (ROM) or flash RAM, and the memory includes at least one memory chip.

[0136] This invention provides a computer-readable storage medium including a stored program, wherein, when the program is executed, it controls the device containing the computer-readable storage medium to perform the method for determining the protection settings of distribution lines considering changes in the distribution network structure.

[0137] This invention provides an electronic device, including a processor, a memory, and a program stored in the memory and executable on the processor. When the processor executes the program, it implements a method for determining the protection settings of distribution lines that take into account changes in the distribution network structure.

[0138] The devices mentioned in this article can be servers, PCs, tablets, mobile phones, etc.

[0139] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the method for determining the protection settings of distribution lines that takes into account changes in the distribution network structure as described in various embodiments of this application.

[0140] It is obvious to those skilled in the art that the modules or steps of the present invention described above can be implemented using general-purpose computing devices. They can be centralized on a single computing device or distributed across a network of multiple computing devices. They can be implemented using computer-executable program code, and thus can be stored in a storage device for execution by a computing device. In some cases, the steps shown or described can be performed in a different order than those described herein, or they can be fabricated as separate integrated circuit modules, or multiple modules or steps can be fabricated as a single integrated circuit module. Thus, the present invention is not limited to any particular combination of hardware and software.

[0141] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0142] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0143] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0144] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0145] In a typical configuration, a computing device includes one or more processors (CPU), input / output interfaces, network interfaces, and memory.

[0146] Memory may include non-persistent memory in computer-readable media, such as random access memory (RAM) and / or non-volatile memory, like read-only memory (ROM) or flash RAM. Memory is an example of computer-readable media.

[0147] Computer-readable media includes both permanent and non-permanent, removable and non-removable media that can store information using any method or technology. Information can be computer-readable instructions, data structures, modules of programs, or other data. Examples of computer storage media include, but are not limited to, phase-change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read-only memory (ROM), electrically erasable programmable read-only memory (EEPROM), flash memory or other memory technologies, CD-ROM, digital versatile optical disc (DVD) or other optical storage, magnetic tape, magnetic magnetic disk storage or other magnetic storage devices, or any other non-transferable medium that can be used to store information accessible by a computing device. As defined herein, computer-readable media does not include transient computer-readable media, such as modulated data signals and carrier waves.

[0148] It should also be noted that the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0149] As can be seen from the above description, the embodiments of this application achieve the following technical effects:

[0150] 1) The method for determining the protection setting of distribution lines considering changes in the distribution network structure in this application involves obtaining the distribution line parameters and zero-sequence overcurrent protection setting of the distribution network, determining the maximum zero-sequence capacitance value to ground based on the distribution line parameters and zero-sequence overcurrent protection setting, obtaining multiple topologies of the distribution lines, determining the zero-sequence capacitance value corresponding to each topology, sorting the multiple zero-sequence capacitance values ​​of the distribution lines in a predetermined order, and comparing each zero-sequence capacitance value with the maximum zero-sequence capacitance value to ground in a predetermined order; then, if the current zero-sequence capacitance value is less than the maximum zero-sequence capacitance value to ground, determining that the distribution line operates under the topology from the first zero-sequence capacitance value to the current zero-sequence capacitance value, and determining the maximum zero-sequence capacitance value to ground as the protection setting of the distribution line. In contrast to existing technologies, the zero-sequence overcurrent protection settings of distribution network line outgoing switches are sometimes inapplicable to certain distribution network topologies, leading to maloperation of the outgoing switches. This application addresses this issue by determining the protection settings for distribution lines based on various distribution network topologies and the zero-sequence overcurrent protection settings. This makes the application suitable for distribution networks with complex topologies, thus improving network reliability. Therefore, it solves the problem of determining line protection settings for different distribution network structures in existing technologies.

[0151] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for determining the protection settings of distribution lines considering changes in the distribution network structure, characterized in that, include: Obtain the power distribution line parameters and zero-sequence overcurrent protection settings of the power distribution network, and determine the maximum zero-sequence capacitance value to ground based on the power distribution line parameters and the zero-sequence overcurrent protection settings. The power distribution network includes at least one power distribution line, the power distribution line includes multiple topologies, and the power distribution line parameters include at least zero-sequence voltage. The system acquires multiple topologies of the power distribution line, determines the zero-sequence capacitance value corresponding to each topology, sorts the multiple zero-sequence capacitance values ​​of the power distribution line in a predetermined order, and compares each zero-sequence capacitance value with the maximum zero-sequence capacitance value to ground in the predetermined order. The first determination step is as follows: If the current zero-sequence capacitance value is less than the maximum zero-sequence capacitance value to ground, determine that the power distribution line operates under the topology corresponding to the first zero-sequence capacitance value to the topology corresponding to the current zero-sequence capacitance value, and determine that the maximum zero-sequence capacitance value to ground is the protection setting value of the power distribution line. The first zero-sequence capacitance value is the first zero-sequence capacitance value arranged in the predetermined order, and the current zero-sequence capacitance value is the current zero-sequence capacitance value arranged in the predetermined order. Determining the maximum zero-sequence capacitance to ground based on the power distribution line parameters and the zero-sequence overcurrent protection setting includes: determining the maximum zero-sequence capacitance to ground based on the power distribution line parameters and the zero-sequence overcurrent protection setting using a formula. Determine the maximum zero-sequence capacitance value to ground, wherein, Indicates the first i The maximum zero-sequence capacitance value to ground mentioned above. Indicates the first i The zero-sequence overcurrent protection setting value is as described above. Represents the reliability coefficient. This represents the zero-sequence voltage of the busbar in the event of a metallic ground fault, where j represents the imaginary part coefficient and ω represents the angular frequency. The method further includes: a second determining step: when the current zero-sequence capacitance value is greater than or equal to the maximum zero-sequence capacitance value to ground, determining that the power distribution line operates under the topology from the topology corresponding to the first zero-sequence capacitance value to the topology corresponding to the previous zero-sequence capacitance value of the current zero-sequence capacitance value, and determining that the current zero-sequence capacitance value is the protection setting value of the power distribution line, wherein the previous zero-sequence capacitance value is the previous zero-sequence capacitance value adjacent to the current zero-sequence capacitance value after being arranged in the predetermined order.

2. The determination method according to claim 1, characterized in that, Determining the zero-sequence capacitance value corresponding to each of the topologies includes: According to the formula Determine the zero-sequence capacitance value corresponding to each of the topologies, wherein, This represents the zero-sequence capacitance value. Indicates the first i The zero-sequence capacitance value of the main line of the distribution line. Indicates the first i The first of the power distribution lines mentioned in Article [number] j The zero-sequence capacitance value of each branch line. i =1,2,…, n, j =1,2,…, m, n Indicates the total number of the power distribution lines. ，m This represents the total number of branch lines in the i-th power distribution line.

3. The determination method according to claim 1, characterized in that, Determining the maximum zero-sequence capacitance to ground value as the protection setting value of the distribution line includes: If the topology corresponding to the current zero-sequence capacitance value is the last topology of the power distribution line, the maximum zero-sequence capacitance value to ground is determined to be the protection setting value of the power distribution line. If the topology corresponding to the current zero-sequence capacitance value is not the last topology of the power distribution line, the first determination step is performed at least once until the topology corresponding to the current zero-sequence capacitance value is the last topology of the power distribution line, and the maximum zero-sequence capacitance value to ground is determined as the protection setting value of the power distribution line.

4. The determination method according to claim 1, characterized in that, After determining that the power distribution line operates under the topology corresponding to the first zero-sequence capacitance value to the topology corresponding to the previous zero-sequence capacitance value, the method further includes: It is determined that the power distribution line will malfunction when operating under the topology corresponding to the current zero-sequence capacitance value and the topology corresponding to the zero-sequence capacitance value after the current zero-sequence capacitance value.

5. The determination method according to claim 1, characterized in that, The process involves sorting the multiple zero-sequence capacitance values ​​of the power distribution line in a predetermined order, and comparing each zero-sequence capacitance value with the maximum zero-sequence capacitance value to ground in the predetermined order, including: The multiple zero-sequence capacitance values ​​of the power distribution line are sorted in ascending order; Each of the zero-sequence capacitance values ​​is compared with the maximum zero-sequence capacitance value to ground in ascending order.

6. A device for determining the protection settings of distribution lines considering changes in the distribution network structure, characterized in that, include: The first determining unit is used to acquire the distribution line parameters and zero-sequence overcurrent protection setting of the distribution network, and determine the maximum zero-sequence capacitance value to ground based on the distribution line parameters and the zero-sequence overcurrent protection setting. The distribution network includes at least one distribution line, the distribution line includes multiple topologies, and the distribution line parameters include at least zero-sequence voltage. A comparison unit is used to acquire multiple topologies of the power distribution line, determine the zero-sequence capacitance value corresponding to each topology, sort the multiple zero-sequence capacitance values ​​of the power distribution line in a predetermined order, and compare each zero-sequence capacitance value with the maximum zero-sequence capacitance value to ground in the predetermined order. The second determining unit is configured to perform the first determining step: when the current zero-sequence capacitance value is less than the maximum zero-sequence capacitance value to ground, determine that the power distribution line operates under the topology from the first zero-sequence capacitance value to the topology corresponding to the current zero-sequence capacitance value, and determine that the maximum zero-sequence capacitance value to ground is the protection setting value of the power distribution line, wherein the first zero-sequence capacitance value is the first zero-sequence capacitance value arranged in the predetermined order, and the current zero-sequence capacitance value is the current zero-sequence capacitance value arranged in the predetermined order. The first determining unit includes a first determining module, which determines the maximum zero-sequence capacitance value to ground based on the power distribution line parameters and the zero-sequence overcurrent protection setting, including: determining the maximum zero-sequence capacitance value to ground based on the power distribution line parameters and the zero-sequence overcurrent protection setting using a formula. Determine the maximum zero-sequence capacitance value to ground, wherein, Indicates the first i The maximum zero-sequence capacitance value to ground mentioned above. Indicates the first i The zero-sequence overcurrent protection setting value is as described above. Represents the reliability coefficient. This represents the zero-sequence voltage of the busbar in the event of a metallic ground fault, where j represents the imaginary part coefficient and ω represents the angular frequency. The device further includes: a third determining unit, configured to perform a second determining step: when the current zero-sequence capacitance value is greater than or equal to the maximum zero-sequence capacitance value to ground, determining that the power distribution line operates under the topology from the topology corresponding to the first zero-sequence capacitance value to the topology corresponding to the previous zero-sequence capacitance value of the current zero-sequence capacitance value, and determining that the current zero-sequence capacitance value is the protection setting value of the power distribution line, wherein the previous zero-sequence capacitance value is the previous zero-sequence capacitance value adjacent to the current zero-sequence capacitance value after being arranged in the predetermined order.

7. A computer-readable storage medium, characterized in that, The computer-readable storage medium includes a stored program, wherein, when the program is executed, it controls the device containing the computer-readable storage medium to perform the method for determining the protection settings of distribution lines considering changes in the distribution network structure as described in any one of claims 1 to 5.

8. An electronic device, characterized in that, include: One or more processors, a memory, and one or more programs, wherein the one or more programs are stored in the memory and configured to be executed by the one or more processors, the one or more programs including a method for performing the determination of distribution line protection settings taking into account changes in the distribution network structure as described in any one of claims 1 to 5.

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