Calculation method and device for closed-loop impulse current of power distribution network, and storage medium

Abstract

The invention discloses a calculation method and device for closed-loop impulse current of a power distribution network and a storage medium. The method belongs to the field of power systems, and comprises the following steps: in response to a fault of the power distribution network, obtaining a fault type of the fault and a current first power parameter of a preset coupling point in the power distribution network; based on the coupling point identifier of the preset coupling point, a second electric power parameter is obtained from an electric power parameter table, the electric power parameter table is used for storing electric power parameters of the preset coupling point at different moments, and the second electric power parameter is used for representing the electric power parameter of the preset coupling point at the previous moment when the power distribution network breaks down; and on the basis of the fault type, the first electric power parameter and the second electric power parameter, loop closing impact current of the power distribution network is determined, and the loop closing impact current is used for representing impact current generated when loop closing operation is carried out on the power distribution network. According to the invention, the technical problem of low calculation accuracy of the closed-loop impulse current of the power distribution network in the prior art is solved.

Description

Technical Field

[0001] The present invention relates to the field of power systems, and in particular to a method and device for calculating a closed-loop impulse current of a distribution network, and a storage medium. Background Art

[0002] In modern power systems, the distribution network serves as a bridge between power plants and end users, and its stable operation is crucial to ensuring the quality and reliability of power supply. In recent years, with the widespread access to distributed power sources (such as solar photovoltaics, wind power generation, etc.), the operation mode and control strategy of the distribution network have faced new challenges. The access of distributed power sources not only changes the power flow distribution of the power grid, but also increases the uncertainty of power grid operation, especially in the closed-loop operation, which puts higher requirements on the accurate calculation and control of the closed-loop current.

[0003] Traditional methods for calculating closed-loop current mainly rely on the superposition principle and the direct power flow method. The superposition principle estimates the closed-loop current through the system superposition effect, but in complex networks containing distributed power sources, the prediction accuracy of the closed-loop current by the superposition effect is low. The direct power flow law is based on the actual parameters of the power grid, such as impedance and admittance, but the calculation process of this method is relatively complex and time-consuming, and it is difficult to meet the requirements of real-time performance and accuracy in the operation of the distribution network.

[0004] To address the above-mentioned problems, no effective solution has been proposed yet. Summary of the invention

[0005] The embodiments of the present invention provide a method and device for calculating the closed-loop impulse current of a distribution network, and a storage medium, so as to at least solve the technical problem of low calculation accuracy of the closed-loop impulse current of the distribution network in the related art.

[0006] According to one aspect of an embodiment of the present invention, there is provided a method for calculating a closed-loop impact current of a distribution network, comprising: in response to a fault in the distribution network, obtaining a fault type of the fault and a current first power parameter of a preset coupling point in the distribution network; based on a coupling point identifier of the preset coupling point, obtaining a second power parameter from a power parameter table, wherein the power parameter table is used to store power parameters of the preset coupling point at different moments, and the second power parameter is used to characterize the power parameters of the preset coupling point at a moment before the fault in the distribution network occurs; based on the fault type, the first power parameter and the second power parameter, determining a closed-loop impact current of the distribution network, wherein the closed-loop impact current is used to characterize an impact current generated when a closed-loop operation is performed on the distribution network.

[0007] Furthermore, based on the fault type, the first power parameter and the second power parameter, the closed-loop impact current of the distribution network is determined, including: based on the first power parameter and the second power parameter, determining the change in the power parameters of the distribution network when a fault occurs; based on the fault type and the change in the power parameters, determining the equivalent resistance of the distribution network; based on the fault type, the equivalent resistance and the second power parameter, determining the open-circuit voltage of the distribution network; based on the equivalent resistance, the open-circuit voltage and the attenuation time constant, determining the closed-loop impact current, wherein the attenuation time constant is used to reflect the process of the current generated by the distribution network when performing a closed-loop operation from a transient state to a steady state.

[0008] Furthermore, the first power parameter includes: a first voltage and a first current at a preset coupling point when a fault occurs in the distribution network, the second power parameter includes: a second voltage and a second current at the preset coupling point at a moment before the fault occurs in the distribution network, and the power parameter change includes: a voltage change and a current change; based on the first power parameter and the second power parameter, determining the power parameter change of the distribution network when a fault occurs, including: obtaining a voltage change based on the difference between the first voltage and the second voltage; obtaining a current change based on the difference between the first current and the second current.

[0009] Furthermore, the fault types include system load fluctuations and system power supply fluctuations. Based on the fault type and the power parameter change, the equivalent resistance of the distribution network is determined, including: obtaining the initial resistance based on the ratio of the voltage change to the current change in the power parameter change; in response to the fault type being system load fluctuations, determining the initial resistance as the equivalent resistance; in response to the fault type being system power supply fluctuations, obtaining the system internal resistance of the distribution network, and obtaining a first resistance based on the product of the initial resistance and the equivalent resistance, obtaining a second resistance based on the sum of the initial resistance and the system content, and obtaining an equivalent resistance based on the quotient of the first resistance and the second resistance.

[0010] Furthermore, based on the fault type, equivalent resistance and the second power parameter, the open circuit voltage of the distribution network is determined, including: in response to the fault type being system load fluctuation, obtaining a third voltage based on the product of the first current and the equivalent current in the first power parameter; and obtaining the open circuit voltage based on the difference between the first voltage and the third voltage in the first power parameter.

[0011] Furthermore, based on the fault type, equivalent resistance and the second power parameter, the open circuit voltage of the distribution network is determined, including: in response to the fault type being system power supply fluctuation, obtaining the system voltage of the distribution network; obtaining the first electric power based on the product of the first voltage and the system internal resistance in the first power parameter, and obtaining the second electric power based on the product of the system voltage and the initial resistance; obtaining the target resistance based on the sum of the initial resistance and the system resistance, and obtaining the third electric power based on the sum of the first electric power and the second electric power; obtaining the open circuit voltage based on the quotient of the third electric power and the target resistance.

[0012] Further, the open circuit voltage includes a first open circuit voltage and a second open circuit voltage at both ends of a closing point in the distribution network, and the equivalent resistance includes a first equivalent resistance and a second equivalent resistance at both ends of the closing point; based on the equivalent resistance, the open circuit voltage and the attenuation time constant, the closing-loop impact current is determined, including: obtaining a third open circuit voltage based on the difference between the first open circuit voltage and the second open circuit voltage, and obtaining a third equivalent resistance based on the sum of the first equivalent resistance and the second equivalent resistance; obtaining a closing-loop steady-state current of the distribution network based on the quotient of the third open circuit voltage and the third equivalent resistance, wherein the closing-loop steady-state current is used to characterize the current generated after the distribution network is closed-loop operated; based on the attenuation time constant and the preset constant, a current attenuation coefficient is constructed; and based on the product of the closing-loop steady-state current and the current attenuation coefficient, the closing-loop impact current is obtained.

[0013] Furthermore, the method also includes: acquiring the system frequency of the distribution network; determining the specific frequency of the distribution network according to a preset frequency function based on the system frequency, wherein the accuracy of the distribution network in describing the attenuation process of the closed-loop impulse current at the specific frequency is higher than the accuracy of the distribution network in describing the attenuation process of the closed-loop impulse current at other frequencies; determining the target impedance corresponding to the specific frequency based on the system frequency and the specific frequency according to a preset impedance function; and determining the attenuation time constant based on the target impedance and the specific frequency according to a preset time function.

[0014] Furthermore, the method also includes: obtaining a current threshold of a distribution network protection device, wherein the distribution network protection device is used to control the distribution network to stop power supply when the closing-loop impact current is greater than the current threshold; in response to the closing-loop impact current being less than or equal to the current threshold, controlling the distribution network to perform a closing-loop operation; in response to the closing-loop impact current being greater than the current threshold, adjusting the operating state of a load device in the distribution network based on the closing-loop impact current to control the closing-loop impact current to be less than or equal to the current threshold.

[0015] According to another aspect of an embodiment of the present invention, there is also provided a device for calculating the closing-loop impact current of a distribution network, comprising: a parameter detection module, for obtaining, in response to a fault in the distribution network, the fault type of the fault and the current first power parameter of a preset coupling point in the distribution network; a parameter acquisition module, for obtaining, based on a coupling point identifier of the preset coupling point, a second power parameter from a power parameter table, wherein the power parameter table is used to store the power parameters of the preset coupling point at different moments, and the second power parameter is used to characterize the power parameters of the preset coupling point at a moment before the fault in the distribution network occurs; a current calculation module, for determining the closing-loop impact current of the distribution network based on the fault type, the first power parameter and the second power parameter, wherein the closing-loop impact current is used to characterize the impact current generated when the distribution network is closed-loop operated.

[0016] Furthermore, the current calculation module is also used to: determine the change in power parameters of the distribution network when a fault occurs based on the first power parameter and the second power parameter; determine the equivalent resistance of the distribution network based on the fault type and the change in power parameters; determine the open circuit voltage of the distribution network based on the fault type, the equivalent resistance and the second power parameter; determine the closed-loop impact current based on the equivalent resistance, the open-circuit voltage and the attenuation time constant, wherein the attenuation time constant is used to reflect the process from transient to steady state of the current generated by the distribution network when performing a closed-loop operation.

[0017] Furthermore, the first power parameter includes: a first voltage and a first current at a preset coupling point when a fault occurs in the distribution network, the second power parameter includes: a second voltage and a second current at the preset coupling point at a moment before the fault occurs in the distribution network, and the power parameter change includes: a voltage change and a current change; the current calculation module is also used to: obtain a voltage change based on the difference between the first voltage and the second voltage; and obtain a current change based on the difference between the first current and the second current.

[0018] Furthermore, the fault types include system load fluctuations and system power supply fluctuations, and the current calculation module is also used to: obtain the initial resistance based on the ratio of the voltage change and the current change in the power parameter change; in response to the fault type being system load fluctuations, determine the initial resistance as an equivalent resistance; in response to the fault type being system power supply fluctuations, obtain the system internal resistance of the distribution network, and obtain the first resistance based on the product of the initial resistance and the equivalent resistance, obtain the second resistance based on the sum of the initial resistance and the system content, and obtain the equivalent resistance based on the quotient of the first resistance and the second resistance.

[0019] Furthermore, the current calculation module is also used to: in response to the fault type being system load fluctuation, obtain a third voltage based on the product of the first current and the equivalent current in the first power parameter; and obtain an open circuit voltage based on the difference between the first voltage and the third voltage in the first power parameter.

[0020] Furthermore, the current calculation module is also used to: in response to the fault type being system power supply fluctuation, obtain the system voltage of the distribution network; obtain the first electric power based on the product of the first voltage in the first power parameter and the system internal resistance, and obtain the second electric power based on the product of the system voltage and the initial resistance; obtain the target resistance based on the sum of the initial resistance and the system resistance, and obtain the third electric power based on the sum of the first electric power and the second electric power; obtain the open circuit voltage based on the quotient of the third electric power and the target resistance.

[0021] Furthermore, the open circuit voltage includes a first open circuit voltage and a second open circuit voltage at both ends of the closing point in the distribution network, and the equivalent resistance includes a first equivalent resistance and a second equivalent resistance at both ends of the closing point; the current calculation module is also used to: obtain a third open circuit voltage based on the difference between the first open circuit voltage and the second open circuit voltage, and obtain a third equivalent resistance based on the sum of the first equivalent resistance and the second equivalent resistance; obtain a closed-loop steady-state current of the distribution network based on the quotient of the third open circuit voltage and the third equivalent resistance, wherein the closed-loop steady-state current is used to characterize the current generated after the distribution network is closed-loop operated; construct a current attenuation coefficient based on the attenuation time constant and the preset constant; and obtain a closed-loop impact current based on the product of the closed-loop steady-state current and the current attenuation coefficient.

[0022] Furthermore, the device also includes: a first acquisition module, used to acquire the system frequency of the distribution network; a first determination module, used to determine the specific frequency of the distribution network according to a preset frequency function based on the system frequency, wherein the accuracy of the distribution network in describing the attenuation process of the closed-loop impulse current at the specific frequency is higher than the accuracy of the distribution network in describing the attenuation process of the closed-loop impulse current at other frequencies; a second determination module, used to determine the target impedance corresponding to the specific frequency based on the system frequency and the specific frequency according to a preset impedance function; and a third determination module, used to determine the attenuation time constant based on the target impedance and the specific frequency according to a preset time function.

[0023] Furthermore, the device also includes: a second acquisition module, used to acquire a current threshold of a distribution network protection device, wherein the distribution network protection device is used to control the distribution network to stop power supply when the closing-loop impact current is greater than the current threshold; a first control module, used to control the distribution network to perform a closing-loop operation in response to the closing-loop impact current being less than or equal to the current threshold; and a second control module, used to adjust the operating state of a load device in the distribution network based on the closing-loop impact current in response to the closing-loop impact current being greater than the current threshold, so as to control the closing-loop impact current to be less than or equal to the current threshold.

[0024] According to another aspect of an embodiment of the present invention, there is further provided an electronic device, comprising: a memory storing an executable program; and a processor for running the program, wherein the method in each embodiment of the present invention is executed when the program is running.

[0025] According to another aspect of an embodiment of the present invention, a computer-readable storage medium is provided. The computer-readable storage medium includes a stored executable program, wherein when the executable program is running, the device where the computer-readable storage medium is located is controlled to execute the methods in various embodiments of the present invention.

[0026] According to another aspect of an embodiment of the present invention, a computer program product is provided, including a computer program. When the computer program is executed by a processor, the method in each embodiment of the present invention is implemented.

[0027] According to another aspect of an embodiment of the present invention, a computer program product is provided, including a non-volatile computer-readable storage medium, wherein the non-volatile computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method in each embodiment of the present invention is implemented.

[0028] According to another aspect of the embodiments of the present invention, a computer program is further provided. When the computer program is executed by a processor, the methods in the embodiments of the present invention are implemented.

[0029] In an embodiment of the present invention, in response to a fault in a distribution network, the fault type of the fault and the current first power parameter of a preset coupling point in the distribution network are obtained; based on the coupling point identifier of the preset coupling point, a second power parameter is obtained from a power parameter table; based on the fault type, the first power parameter and the second power parameter, a closed-loop impact current of the distribution network is determined. By utilizing the power parameters before and after the fault in the distribution network and combining the fault type of the fault to determine the impact current that may be generated when the distribution network is closed, the accuracy of the determined impact current can be guaranteed, thereby solving the technical problem of low calculation accuracy of the closed-loop impact current of the distribution network in the related art. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of this application. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0031] Figure 1 is a flow chart of a method for calculating a closed-loop impulse current of a distribution network according to an embodiment of the present invention;

[0032] Figure 2 is a schematic diagram of an optional distribution network topology result and an equivalent model construction method thereof according to an embodiment of the present invention;

[0033] Figure 3 is a schematic diagram of an optional distribution network closed-loop current calculation process according to an embodiment of the present invention;

[0034] Figure 4 is an optional distribution network simulation schematic diagram according to an embodiment of the present invention;

[0035] Figure 5 is a schematic diagram of changes in equivalent impedance under different optional disturbance modes according to an embodiment of the present invention;

[0036] Figure 6 is a schematic diagram of changes in equivalent reactance under different optional disturbance modes according to an embodiment of the present invention;

[0037] Figure 7 is a schematic diagram of changes in the effective value of the open circuit voltage under different optional disturbance modes according to an embodiment of the present invention;

[0038] Figure 8 is a schematic diagram of the change of the open circuit voltage phase under different optional disturbance modes according to an embodiment of the present invention;

[0039] Fig. 9 is a schematic diagram of changes in system active power response under an optional load disturbance condition according to an embodiment of the present invention;

[0040] Fig.10 is a schematic diagram of changes in system reactive power response under an optional load disturbance condition according to an embodiment of the present invention;

[0041] Fig.11 is a schematic diagram of a change in an optional closed-loop current effective value according to an embodiment of the present invention;

[0042] Fig.12 is a schematic diagram of an optional change of the phase of the closed-loop current according to an embodiment of the present invention;

[0043] Fig.13 It is a schematic diagram of a device for calculating a closed-loop impulse current of a distribution network according to an embodiment of the present invention. DETAILED DESCRIPTION

[0044] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0045] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0046] According to an embodiment of the present invention, an embodiment of a method for calculating the closed-loop impulse current of a distribution network is provided. It should be noted that the steps shown in the flowchart of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and although a logical order is shown in the flowchart, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0047] Figure 1 is a flow chart of a method for calculating a distribution network closing loop inrush current according to an embodiment of the present invention. Figure 1 As shown, the method comprises the following steps:

[0048] Step S102: in response to a fault occurring in the distribution network, obtaining a fault type and a current first power parameter of a preset coupling point in the distribution network.

[0049] The above-mentioned fault type may refer to the type of disturbance that causes the distribution network to be disturbed. For example, the above-mentioned fault category may include at least one or more of the following: load changes, distributed power source fluctuations, but not limited to them. The above-mentioned preset coupling point may refer to a pre-set point where multiple power users, distributed power sources or other power facilities are connected to the power grid. For example, the above-mentioned preset coupling point may be a common coupling point in the distribution network, but not limited to it. The above-mentioned first power parameter may be a power parameter used to reflect the operating status of the preset coupling point. For example, the above-mentioned first power parameter may be the voltage and injected current after the disturbance occurs, but not limited to it.

[0050] In an optional embodiment, considering that obtaining accurate power parameters is a necessary condition for accurately calculating the closed-loop current when performing the closed-loop operation of the distribution network, the closed-loop current calculation system of the distribution network (hereinafter referred to as the calculation system) can use data acquisition equipment to detect the power parameters of the common coupling point in real time and return the parameters to the calculation system. When a fault occurs in the distribution network, the calculation system can infer the current fault type of the distribution network by analyzing the changes in the power parameters at different times, and parse the above-mentioned first power parameter from the above-mentioned power parameters, thereby providing a data basis for the subsequent calculation of the closed-loop current.

[0051] For example, the preset coupling point may be a common coupling point in the distribution network, and the first power parameter may be the voltage and injected current of the preset coupling point. In order to accurately obtain the fault type and the first power parameter, the staff may deploy multiple power sensing devices in the distribution network in advance, such as smart meters, power sensors, etc., to detect the power parameters of the common coupling point in real time and return the power parameters to the computing system. When a fault occurs in the distribution network, the computing system may analyze the power parameters returned by the power sensing devices at different times, and infer that the current disturbance type of the common coupling point is load change through the changes in current and voltage. Subsequently, the computing system may further analyze the voltage and current of the common coupling point after the disturbance based on the power parameters.

[0052] Step S104: acquiring a second power parameter from a power parameter table based on a coupling point identifier of a preset coupling point.

[0053] The power parameter table is used to store power parameters of the preset coupling point at different times, and the second power parameter is used to characterize the power parameter of the preset coupling point at a time before a fault occurs in the distribution network.

[0054] The coupling point identifier may be an identifier for distinguishing the coupling point before and after a fault occurs in the distribution network. The power parameter table may be a table for storing power parameters of preset coupling points at different times. The second power parameter may be a power parameter of the preset coupling point at a moment before a fault occurs in the distribution network. For example, the second power parameter may include at least one or more of the following: voltage before a disturbance occurs in the distribution network, current before a disturbance occurs in the distribution network, etc., but is not limited thereto.

[0055] In an optional embodiment, considering the historical power parameters of the distribution network before the fault occurs, it can reflect the operating state of the distribution network before the fault occurs. By analyzing the above historical power parameters, it is possible to determine the current changes that may be caused after the ring closing operation, so as to improve the stability of the distribution network operation after the ring closing operation. Therefore, the computing system can first store the monitored power parameters in a pre-constructed power parameter table. When the distribution network fails, the computing system can determine the coupling point identifier of the current preset coupling point, and obtain the above second power parameter from the power parameter table based on the coupling point identifier.

[0056] For example, in order to ensure the stable operation of the distribution network after the ring closing operation, the computing system can pre-build a power parameter table based on the above coupling point identifier, and then the computing system can store multiple power parameters of different coupling points monitored at different times in the above power parameter table according to the coupling point identifier, so that the computing system can obtain the power parameters of the current coupling point at different times from the power parameter table based on the current coupling point identifier. After the storage of power parameters is completed, when a fault occurs in the distribution network, the computing system can obtain the power parameters of the preset coupling point at the previous moment of the fault from the power parameter table based on the coupling point identifier of the preset coupling point, that is, the above second power parameter.

[0057] Step S106, determining the closed-loop inrush current of the distribution network based on the fault type, the first power parameter and the second power parameter.

[0058] The closing-loop inrush current is used to characterize the inrush current generated when the distribution network is closed-loop operated.

[0059] The above-mentioned closing-loop impact current may refer to the instantaneous current fluctuation caused by the transient characteristics of the system at the moment of closing-loop operation.

[0060] In an optional embodiment, considering that the power parameters of the distribution network before the disturbance can provide a parameter benchmark for the normal operation of the power grid, and the power parameters of the distribution network after the disturbance reflect the real-time status of the power grid, by comparing and analyzing these data, the changes in the operating status of the distribution network can be evaluated in combination with the characteristics of different disturbance types without introducing new disturbance signals, so that the computing system can more accurately calculate the current impact that may be generated by the closing-loop operation. Therefore, the computing system can calculate the closing-loop impact current of the distribution network during the closing-loop operation based on the fault type, the first power parameter and the second power parameter, without injecting additional disturbance signals, thereby avoiding interference with the operation of the distribution network system.

[0061] For example, the above-mentioned fault type may be a load change, the above-mentioned first power parameter is the voltage and current after the distribution network is disturbed, and the above-mentioned second power parameter is the voltage and current before the distribution network is disturbed. In order to accurately calculate the above-mentioned closed-loop impact current, the computing system can first analyze the disturbance characteristics under the load change scenario, that is, since the disturbance source of the load change is located near the closing point, the impedance of the line where it is located can be ignored. At this time, the load change does not affect the closing point voltage, and the open circuit voltage and equivalent impedance remain unchanged. Based on the above disturbance characteristics, the computing system does not need to inject additional disturbance signals, but can calculate the closed-loop impact current of the distribution network based on the voltage and current after the distribution network is disturbed, as well as the voltage and current before the distribution network is disturbed, thereby avoiding injecting additional disturbance signals to interfere with the operation of the distribution network system.

[0062] In an embodiment of the present invention, in response to a fault in a distribution network, the fault type of the fault and the current first power parameter of a preset coupling point in the distribution network are obtained; based on the coupling point identifier of the preset coupling point, a second power parameter is obtained from a power parameter table; based on the fault type, the first power parameter and the second power parameter, a closed-loop impact current of the distribution network is determined. By utilizing the power parameters before and after the fault in the distribution network and combining the fault type of the fault to determine the impact current that may be generated when the distribution network is closed, the accuracy of the determined impact current can be guaranteed, thereby solving the technical problem of low calculation accuracy of the closed-loop impact current of the distribution network in the related art.

[0063] Furthermore, based on the fault type, the first power parameter and the second power parameter, the closed-loop impact current of the distribution network is determined, including: based on the first power parameter and the second power parameter, determining the change in the power parameters of the distribution network when a fault occurs; based on the fault type and the change in the power parameters, determining the equivalent resistance of the distribution network; based on the fault type, the equivalent resistance and the second power parameter, determining the open-circuit voltage of the distribution network; based on the equivalent resistance, the open-circuit voltage and the attenuation time constant, determining the closed-loop impact current, wherein the attenuation time constant is used to reflect the process of the current generated by the distribution network when performing a closed-loop operation from a transient state to a steady state.

[0064] The power parameter change amount may be the power parameter of the distribution network after the disturbance occurs, compared with the power parameter before the disturbance occurs. The decay time constant may be a constant used to reflect the decay process of the impulse current from transient to steady state.

[0065] In an optional embodiment, considering that there is no need to inject additional disturbance signals into the distribution network, by monitoring the voltage and current changes of the distribution network under natural disturbances, the above-mentioned additional disturbance signals can be prevented from interfering with the operation of the distribution network system. Therefore, the computing system can directly determine the power parameter changes of the distribution network when a fault occurs based on the above-mentioned first power parameter and the second power parameter. Further considering that the calculation method of the equivalent resistance of the distribution network is different under different fault types, therefore, the computing system needs to calculate the equivalent resistance of the distribution network under the current fault type using the above-mentioned power parameter changes according to the current fault type, and further determine the open circuit voltage of the distribution network based on the fault type, the equivalent resistance and the second power parameter. Further considering that the closed-loop impulse current is not constant, but will decay to a new steady-state level over time, and the decay time constant reflects the rate of this decay process, therefore, the computing system can determine the closed-loop impulse current based on the equivalent resistance, the open-circuit voltage and the decay time constant, thereby improving the calculation accuracy of the closed-loop impulse current.

[0066] For example, the computing system has acquired the above-mentioned first power parameter and the second power parameter, the above-mentioned first power parameter is the voltage and current after the disturbance of the distribution network, and the above-mentioned second power parameter is the voltage and current before the disturbance of the distribution network. At this time, the computing system can calculate the change of the current and voltage of the distribution network before and after the disturbance based on the above-mentioned first power parameter and the second power parameter. Then, the computing system can calculate the equivalent impedance of the distribution network system based on the current fault type and the change of the above-mentioned current and voltage, thereby avoiding the interference of the additional injection of the disturbance signal on the operation of the above-mentioned system. Subsequently, the computing system can calculate the open circuit voltage of the distribution network system based on the current fault type and the value of the voltage and current after the disturbance, so as to ensure that the computing system can accurately describe the actual operating state of the distribution network system under different voltage conditions before and after the closing loop operation. Finally, the computing system can calculate the closing loop impact current based on the calculated equivalent resistance, open circuit voltage and decay time constant, so as to effectively improve the calculation accuracy of the closing loop impact current under different disturbances, thereby ensuring the accuracy and reliability of the current calculation during the closing loop operation.

[0067] Furthermore, the first power parameter includes: a first voltage and a first current at a preset coupling point when a fault occurs in the distribution network, the second power parameter includes: a second voltage and a second current at the preset coupling point at a moment before the fault occurs in the distribution network, and the power parameter change includes: a voltage change and a current change; based on the first power parameter and the second power parameter, determining the power parameter change of the distribution network when a fault occurs, including: obtaining a voltage change based on the difference between the first voltage and the second voltage; obtaining a current change based on the difference between the first current and the second current.

[0068] The first voltage may be the voltage of the distribution network when a disturbance occurs. The first current may be the current of the distribution network when a disturbance occurs. The second voltage may be the voltage at a moment before a fault occurs in the distribution network. The second current may be the current at a moment before a fault occurs in the distribution network. The voltage variation may be the difference between the first voltage and the second voltage. The current variation may be the difference between the first current and the second current.

[0069] In an optional embodiment, considering that in the calculation process of the closed-loop impact current, it is necessary to obtain the equivalent impedance of the distribution network, and the equivalent impedance is calculated based on the voltage and current of the distribution network before and after the disturbance occurs, therefore, the calculation system can first obtain the voltage and current of the preset coupling point when the distribution network fails, and the voltage and current at the moment before the distribution network fails. Then, the calculation system can obtain the above voltage change by calculating the difference between the voltage when the distribution network fails and the voltage at the moment before the distribution network fails, and can obtain the above current change by calculating the difference between the current when the distribution network fails and the current at the moment before the distribution network fails.

[0070] For example, the calculation process of the above voltage change can be shown as follows:

[0071]

[0072] In the formula, Indicates the voltage change at the preset coupling point, U PCC1 represents the first voltage, U P ′ CC1 represents the second voltage. The calculation process of the current change can be shown as follows:

[0073]

[0074] In the formula, Indicates the current change at the preset coupling point, I PCC1 represents the first current, I ′ PCC1 According to the above formula, the calculation system can calculate the voltage change based on the first voltage and the second voltage, and can calculate the current change based on the first current and the second current.

[0075] Furthermore, the fault types include system load fluctuations and system power supply fluctuations. Based on the fault type and the power parameter change, the equivalent resistance of the distribution network is determined, including: obtaining the initial resistance based on the ratio of the voltage change to the current change in the power parameter change; in response to the fault type being system load fluctuations, determining the initial resistance as the equivalent resistance; in response to the fault type being system power supply fluctuations, obtaining the system internal resistance of the distribution network, and obtaining a first resistance based on the product of the initial resistance and the equivalent resistance, obtaining a second resistance based on the sum of the initial resistance and the system content, and obtaining an equivalent resistance based on the quotient of the first resistance and the second resistance.

[0076] The initial resistance may be the equivalent resistance characteristic exhibited by the coupling point in the circuit after a disturbance occurs in the distribution network. The system internal resistance may refer to the resistance characteristic of the circuit from the power source to the load in the distribution network system when transmitting power. The first resistance may refer to the product of the initial resistance and the equivalent resistance. The second resistance may be the sum of the initial resistance and the system internal resistance.

[0077] In an optional embodiment, considering that when the closing operation of the distribution network is performed, the current magnitude at the moment of closing the loop can be predicted by calculating the value of the equivalent resistance, so as to avoid protection tripping or equipment damage caused by excessive closing current. Specifically, when the distribution network is disturbed, the change in voltage and current can be regarded as part of the system response, and their ratio reflects the equivalent circuit characteristics of the system at the disturbance point. Therefore, the calculation system can obtain the above-mentioned initial resistance based on the ratio of the voltage change and the current change in the power parameter change. Further considering that different fault types have different effects on the operation of the distribution network, for example, load fluctuations will change the load characteristics of the power grid, but usually will not significantly change the structure and power characteristics of the power grid. Therefore, when the above-mentioned fault type is system load fluctuations, the calculation system can determine that the initial resistance is an equivalent resistance. For another example, system power fluctuations may have a more complex impact on the equivalent circuit parameters of the power grid. In this case, in addition to calculating the initial resistance, it is also necessary to calculate the system internal resistance. Therefore, when the above-mentioned fault type is system power fluctuations, the calculation system can first obtain the system internal resistance of the distribution network. Further considering that in the case of system power fluctuations, the product of the initial resistance and the equivalent resistance can be regarded as the response of the power grid to power fluctuations under specific disturbance conditions, and the sum of the initial resistance and the system internal resistance reflects the state of the power grid under the combined effect of power fluctuations and the system inherent impedance. Therefore, the calculation system can obtain the first resistance based on the product of the initial resistance and the equivalent resistance, and sum the initial resistance and the system internal resistance to calculate the second resistance. Finally, in order to quantify the impedance change of the distribution network system under disturbances and provide more accurate parameters for subsequent current calculation and fault analysis, the calculation system can divide the first resistance and the second resistance to obtain the equivalent resistance.

[0078] For example, in order to accurately calculate the equivalent resistance of the distribution network, the calculation process of the above initial resistance can be shown as follows:

[0079]

[0080] In the formula, Z eq1 represents the initial resistance, Indicates the voltage change at the preset coupling point, It represents the current change at the preset coupling point. The other symbols in the formula are consistent with the above formula and will not be repeated here. When the fault type is system load fluctuation, the calculation process of the above equivalent resistance can be shown as follows:

[0081] Z eqa =Z eq1 .

[0082] In the formula, Z eqa Represents the equivalent resistance, and the interpretation of other symbols in the formula is consistent with the above formula, which will not be repeated here. When the fault type is system power fluctuation, the calculation process of the above equivalent resistance can be shown as follows:

[0083]

[0084] In the formula, Z eqa Represents the equivalent resistance, Z DG Represents the system internal resistance, and the interpretations of other symbols in the formula are consistent with the above formula and will not be repeated here. Based on the above formula, the calculation system can more accurately calculate the equivalent resistance of the distribution network under system load fluctuations and system power supply fluctuations.

[0085] Furthermore, based on the fault type, equivalent resistance and the second power parameter, the open circuit voltage of the distribution network is determined, including: in response to the fault type being system load fluctuation, obtaining a third voltage based on the product of the first current and the equivalent current in the first power parameter; and obtaining the open circuit voltage based on the difference between the first voltage and the third voltage in the first power parameter.

[0086] The third voltage may refer to the product of the first current and the equivalent current.

[0087] In an optional embodiment, considering that it is crucial to understand the voltage state of the closing point before performing the closing operation to avoid excessive closing impact current and ensure stable operation of the power grid, when the fault type is system load fluctuation, the computing system can obtain the third voltage based on the product of the first current and the equivalent current in the first power parameter, and obtain the open circuit voltage based on the difference between the first voltage and the third voltage in the first power parameter.

[0088] For example, in order to accurately calculate the open circuit voltage of the distribution network, when the above fault type is system load fluctuation, the calculation process of the above open circuit voltage can be shown as follows:

[0089]

[0090] In the formula, It indicates the open circuit voltage of the distribution network when the above fault type is system load fluctuation. represents the above-mentioned first voltage, represents the first current, Zeq1 Based on the above formula, the calculation system can more accurately calculate the open circuit voltage of the distribution network when the above fault type is system load fluctuation.

[0091] Furthermore, based on the fault type, equivalent resistance and the second power parameter, the open circuit voltage of the distribution network is determined, including: in response to the fault type being system power supply fluctuation, obtaining the system voltage of the distribution network; obtaining the first electric power based on the product of the first voltage and the system internal resistance in the first power parameter, and obtaining the second electric power based on the product of the system voltage and the initial resistance; obtaining the target resistance based on the sum of the initial resistance and the system resistance, and obtaining the third electric power based on the sum of the first electric power and the second electric power; obtaining the open circuit voltage based on the quotient of the third electric power and the target resistance.

[0092] The first electric power may be the product of the first voltage in the first power parameter and the system internal resistance. The second electric power may be the product of the system voltage and the initial resistance. The target resistance may be the sum of the initial resistance and the system resistance. The third electric power may be the sum of the first electric power and the second electric power.

[0093] In an optional embodiment, considering that in the case of power fluctuations, the change in open circuit voltage can provide real-time information about the voltage difference at the closing point, thereby improving the accuracy of calculating the closing steady-state current and the impact current, the computing system can first obtain the system voltage of the distribution network, and obtain the first electric power based on the product of the first voltage and the system internal resistance in the first power parameter. Then, the computing system can calculate the product of the system voltage and the initial resistance to obtain the second electric power. Subsequently, the computing system can calculate the sum of the initial resistance and the system resistance to obtain the target resistance, and calculate the sum of the first electric power and the second electric power to obtain the third electric power. Finally, the computing system can obtain the open circuit voltage when the fault type is system power fluctuation based on the quotient of the third electric power and the target resistance.

[0094] For example, in order to accurately calculate the open circuit voltage of the distribution network, when the above fault type is system power fluctuation, the calculation process of the above open circuit voltage can be shown as follows:

[0095]

[0096] In the formula, Indicates the open circuit voltage of the distribution network when the above fault type is system power fluctuation. represents the first voltage, Z DG represents the internal resistance of the system, Indicates the system voltage, Z eq1Represents the initial resistance. Based on the above formula, the calculation system can more accurately calculate the open circuit voltage of the distribution network when the above fault type is system power fluctuation.

[0097] Further, the open circuit voltage includes a first open circuit voltage and a second open circuit voltage at both ends of a closing point in the distribution network, and the equivalent resistance includes a first equivalent resistance and a second equivalent resistance at both ends of the closing point; based on the equivalent resistance, the open circuit voltage and the attenuation time constant, the closing-loop impact current is determined, including: obtaining a third open circuit voltage based on the difference between the first open circuit voltage and the second open circuit voltage, and obtaining a third equivalent resistance based on the sum of the first equivalent resistance and the second equivalent resistance; obtaining a closing-loop steady-state current of the distribution network based on the quotient of the third open circuit voltage and the third equivalent resistance, wherein the closing-loop steady-state current is used to characterize the current generated after the distribution network is closed-loop operated; based on the attenuation time constant and the preset constant, a current attenuation coefficient is constructed; and based on the product of the closing-loop steady-state current and the current attenuation coefficient, the closing-loop impact current is obtained.

[0098] The above-mentioned first open-circuit voltage may refer to the voltage at one of the two ends of the closing point. The above-mentioned second open-circuit voltage may refer to the voltage at one of the two ends of the closing point, which is different from the voltage at one end of the above-mentioned first open-circuit voltage. The above-mentioned first equivalent resistance may refer to the equivalent resistance at one of the two ends of the closing point. The above-mentioned second equivalent resistance may refer to the equivalent resistance at one of the two ends of the closing point, which is different from the first equivalent resistance. The above-mentioned third open-circuit voltage may be the difference between the above-mentioned first open-circuit voltage and the second open-circuit voltage. The above-mentioned third equivalent resistance may be the sum of the above-mentioned first equivalent resistance and the second equivalent resistance. The above-mentioned closing steady-state current may refer to the current flowing through the closing point when the system reaches a stable state. The above-mentioned preset constant may be a pre-set constant used to calculate the current attenuation coefficient.

[0099] In an optional embodiment, considering that the open circuit voltage is one of the key parameters for predicting the closed-loop steady-state current and the impact current, according to the Thevenin theorem, the distribution network can be equivalent to a voltage source and an impedance in series. By calculating the open circuit voltage and equivalent impedance at both ends of the closed-loop point, the current flowing through the closed-loop point after the closed-loop operation can be more accurately calculated. Therefore, the computing system can first calculate the difference between the first open circuit voltage and the second open circuit voltage based on the first open circuit voltage and the second open circuit voltage at both ends of the closed-loop point in the distribution network to obtain the third open circuit voltage, and calculate the sum of the first equivalent resistance and the second equivalent resistance based on the first equivalent resistance and the second equivalent resistance at both ends of the closed-loop point in the distribution network to obtain the third equivalent resistance. Then, the computing system can calculate the quotient of the third open circuit voltage and the third equivalent resistance to obtain the closed-loop steady-state current of the distribution network. Finally, the computing system can construct a current attenuation coefficient based on the attenuation time constant and the preset constant, and obtain the closed-loop impact current based on the product of the closed-loop steady-state current and the current attenuation coefficient.

[0100] For example, in order to accurately calculate the above-mentioned closed-loop impulse current, the calculation process of the above-mentioned closed-loop steady-state current can be shown as follows:

[0101]

[0102] In the formula, represents the above closed-loop steady-state current, represents the first open circuit voltage, represents the second open circuit voltage, Z eqa represents the first equivalent resistance mentioned above, Z eqb Represents the second equivalent resistance. The calculation process of the above closed-loop impact current can be shown as follows:

[0103]

[0104] In the formula, Indicates the loop impact current, T a Represents the decay time constant of the non-periodic component of the closed-loop current. Based on the above formula, the calculation system can calculate the closed-loop inrush current more accurately.

[0105] Furthermore, the method also includes: acquiring the system frequency of the distribution network; determining the specific frequency of the distribution network according to a preset frequency function based on the system frequency, wherein the accuracy of the distribution network in describing the attenuation process of the closed-loop impulse current at the specific frequency is higher than the accuracy of the distribution network in describing the attenuation process of the closed-loop impulse current at other frequencies; determining the target impedance corresponding to the specific frequency based on the system frequency and the specific frequency according to a preset impedance function; and determining the attenuation time constant based on the target impedance and the specific frequency according to a preset time function.

[0106] The preset frequency function may be a pre-set function for calculating the frequency of the distribution network system. The preset impedance function may be a pre-set function for calculating the target impedance. The preset time function may be a pre-set function for determining the attenuation time constant.

[0107] In an optional embodiment, in order to accurately obtain the above-mentioned attenuation time constant, the system frequency of the distribution network can be first obtained, and based on the system frequency, the specific frequency of the distribution network can be determined according to a preset frequency function, and then the target impedance corresponding to the specific frequency can be determined based on the system frequency and the specific frequency according to a preset impedance function, and finally the attenuation time constant can be determined based on the target impedance and the specific frequency according to a preset time function. Among them, the accuracy of the distribution network in describing the attenuation degree of the closed-loop impulse current at different frequencies is different, and correspondingly, the accuracy of the distribution network in describing the attenuation process of the closed-loop impulse current at a specific frequency is higher than the accuracy of the distribution network in describing the attenuation process of the closed-loop impulse current at other frequencies.

[0108] The above preset frequency function can be expressed as follows:

[0109]

[0110] In the formula, f c For the above specific frequency, Z eq (f c ) represents the preset frequency function, f n is the above system frequency. The calculation process of the above attenuation time constant can be shown as follows:

[0111]

[0112] Where, T a is the decay time constant, R eq (f c ) is the target impedance corresponding to a specific frequency. Based on the above formula, the calculation system can calculate the attenuation time constant more accurately.

[0113] Furthermore, the method also includes: obtaining a current threshold of a distribution network protection device, wherein the distribution network protection device is used to control the distribution network to stop power supply when the closing-loop impact current is greater than the current threshold; in response to the closing-loop impact current being less than or equal to the current threshold, controlling the distribution network to perform a closing-loop operation; in response to the closing-loop impact current being greater than the current threshold, adjusting the operating state of a load device in the distribution network based on the closing-loop impact current to control the closing-loop impact current to be less than or equal to the current threshold.

[0114] The above-mentioned distribution network protection device may be a device for controlling the distribution network to start or stop power supply.

[0115] In an optional embodiment, considering that the setting of the current threshold is based on the carrying capacity and protection requirements of the power grid equipment, it defines the maximum current value allowed to pass through the circuit under normal operation and fault conditions. If the above maximum current value is exceeded, it may cause unstable operation of the distribution network, which may lead to more extensive power failures. Therefore, before performing the closing-loop operation, the computing system needs to judge the size of the closing-loop impact current. If the closing-loop impact current is less than or equal to the current threshold, the computing system can control the distribution network to perform the closing-loop operation. If the closing-loop impact current is greater than the current threshold, the computing system can control the distribution network to stop supplying power, and adjust the operating status of the load equipment in the distribution network based on the closing-loop impact current to control the closing-loop impact current to be less than or equal to the current threshold, thereby completing the closing-loop operation.

[0116] For ease of understanding, Figure 2 is a schematic diagram of an optional distribution network topology result and an equivalent model construction method thereof according to an embodiment of the present invention, such as Figure 2As shown, the present invention adopts an equivalent model construction method based on the Thevenin theorem, which divides the complex power distribution system into an external system and an internal system, wherein the external system may include an external system 1 and an external system 2 on both sides of the closed loop position, and the internal system may include two preset coupling points PCC1 and PCC2. The external system corresponds to the power distribution network, which is simplified to an open circuit voltage (in the figure) through equivalent processing. and ) and equivalent impedance (Z eqa and Z eqb ), and the internal system covers the distributed source loads at the closing point and its vicinity, which are used as disturbance sources to capture the dynamic changes of the external system. According to the external system and the internal system, the corresponding distribution network equivalent model can be constructed.

[0117] Figure 3 1 is a schematic diagram of an optional distribution network closed-loop current calculation process according to an embodiment of the present invention, wherein equations 1-8 may refer to the aforementioned formulas used to determine the closed-loop impulse current, and the meanings of the symbols in the figure are consistent with the aforementioned formulas and are not described in detail herein. Figure 3 As shown, according to the disturbance of the internal system, a dynamic monitoring system based on a dual-stack structure is used to obtain the voltage and current at the PCC before and after the disturbance. The equivalent impedance and open-circuit voltage of the external system are calculated using the above formula. When the internal system contains distributed power sources such as photovoltaics (PV), further calculations are required in combination with the above formula to construct an equivalent model of the entire distribution network system. The equivalent impedance and open-circuit voltage of the systems on both sides are used as inputs, and the steady-state current is calculated using the above formula. Combined with the optimal frequency method, the specific frequency f is determined according to the above formula c The equivalent impedance Z under eq (f c ), and calculate the attenuation time constant T of the impulse current by the above formula a , and finally the loop-closing inrush current is obtained using the above formula. The entire process achieves accurate calculation of the steady-state and inrush currents of the distribution network system through dynamic monitoring and equivalent modeling, providing reliable technical support for actual grid loop-closing operations.

[0118] Figure 4 is an optional distribution network simulation schematic diagram according to an embodiment of the present invention, such as Figure 4 As shown in the figure, different control strategies were simulated and verified in the Matlab / Simul ink environment, and the model was built based on the 10kV distribution network system. The simulation model includes components such as transformers, transmission lines, loads, and photovoltaic power generation, simulating the operation of the actual distribution network and the closed-loop operation process. By applying disturbances, the voltage and current changes before and after the closed-loop operation of the system and the accurate calculation of the closed-loop current were verified.

[0119] Figure 5 is a schematic diagram of changes in equivalent impedance under different optional disturbance modes according to an embodiment of the present invention, Figure 6 is a schematic diagram of changes in equivalent reactance under different optional disturbance modes according to an embodiment of the present invention, Figure 7 is a schematic diagram of the change of the effective value of the open circuit voltage under different optional disturbance modes according to an embodiment of the present invention, Figure 8 FIG. 1 is a schematic diagram of the change of the open circuit voltage phase under different disturbance modes according to an optional embodiment of the present invention. Figure 5 As shown, the horizontal axis represents time in seconds, the vertical axis represents resistance value in ohms, the solid line represents the change of equivalent resistance under load fluctuation conditions in working conditions 1, 2 and 3, and the dotted line represents the change of equivalent resistance under PV disturbance conditions in working conditions 1, 2 and 3. Figure 6 As shown, the horizontal axis represents time in seconds, the vertical axis represents the reactance value in ohms, the solid line represents the change of equivalent reactance under conditions 1, 2 and 3 under load fluctuation, and the dotted line represents the change of equivalent reactance under conditions 1, 2 and 3 under PV disturbance. Figure 7 As shown, the horizontal axis represents time in seconds, the vertical axis represents the effective value of the open circuit voltage in kilovolts, the solid line represents the change of the effective value of the open circuit voltage under conditions 1, 2 and 3 under load fluctuations, and the dotted line represents the change of the effective value of the open circuit voltage under conditions 1, 2 and 3 under PV disturbances. Figure 8 As shown, the horizontal axis represents time in seconds, the vertical axis represents the open circuit voltage phase in degrees, the solid line represents the change of the open circuit voltage phase under conditions 1, 2 and 3 under load disturbance, and the dotted line represents the change of the open circuit voltage phase under conditions 1, 2 and 3 under PV fluctuation. Figure 5 , Figure 6 , Figure 7 , Figure 8 From the content, we can know that the simulation uses photovoltaic fluctuations and load disturbances to calculate the equivalent impedance and voltage of the system in the initial state, and then adds three-phase balanced load and three-phase unbalanced load respectively to analyze their impact on the equivalent parameters. 1 to 3 seconds are the calculation results under the initial state of the system, 3 to 5 seconds are the results under the three-phase balanced load disturbance, and 5 to 7 seconds are the results under the three-phase unbalanced load disturbance. The results show that despite different types of disturbances, the equivalent impedance and voltage of the system change little, verifying the stability of the system.

[0120] Fig. 9 is a schematic diagram of changes in system active power response under an optional load disturbance condition according to an embodiment of the present invention, Fig.10is a schematic diagram of a change in system reactive power response under an optional load disturbance condition according to an embodiment of the present invention, such as Fig. 9 As shown, the horizontal axis represents time in seconds, the vertical axis represents active power in watts, the solid line represents the change in active power of the equivalent model, and the dotted line represents the change in active power of the actual model. Fig.10 As shown, the horizontal axis represents time in seconds, the vertical axis represents reactive power in var, the solid line represents the reactive power change of the equivalent model, and the dotted line represents the reactive power change of the actual model. Fig. 9 and Fig.10 From the content, we can know that in order to verify the accuracy of the equivalent model, a simulation model of equivalent impedance and equivalent voltage source in series was constructed, and the power response of the actual system under the same disturbance conditions was compared. The load disturbance was applied at 2.5 seconds, and the active and reactive responses of the actual system and the equivalent system were recorded. The response curves of the two almost completely overlap, indicating that the calculation accuracy of the equivalent model under power disturbance is high, which further verifies the effectiveness of this method.

[0121] Fig.11 is a schematic diagram of a change in an optional closed-loop current effective value according to an embodiment of the present invention, Fig.12 is a schematic diagram of an optional change in the phase of the closed-loop current according to an embodiment of the present invention, such as Fig.11 As shown in the figure, the horizontal axis represents time in seconds, and the vertical axis represents current in amperes. The legend in the figure has given the meaning of each line, which will not be repeated here. Fig.12 As shown, the horizontal axis represents time in seconds, and the vertical axis represents phase in degrees. The solid line in the figure represents the phase change of the actual current, and the dotted line represents the phase change of the steady-state current calculation value. Fig.11 and Fig.12 It can be seen from the content that the accuracy of the calculation method is verified by comparing the calculation results with the actual measured values. The errors of the equivalent model and closed-loop current calculation method in steady-state current, impulse current and current phase are 0.31%, 0.11% and 1.39% respectively, which are all controlled within a reasonable range and show high calculation accuracy, further proving that the model and method can provide strong support for closed-loop current calculation in complex distribution network scenarios.

[0122] Finally, the above simulation results show that the closed-loop current passive calculation method based on the Thevenin theorem proposed in the present invention can effectively realize high-precision closed-loop current calculation under different disturbance modes, and there is no need to inject additional disturbance signals, thereby ensuring the safety and stability of the system.

[0123] According to an embodiment of the present invention, an embodiment of a device for calculating a closed-loop impulse current of a distribution network is provided. It should be noted that the device can be used to execute the above-mentioned method for calculating a closed-loop impulse current of a distribution network. The specific implementation method and application scenario are the same as those of the above-mentioned embodiment and will not be described in detail here. Fig.13 is a schematic diagram of a device for calculating a closed-loop impulse current of a distribution network according to an embodiment of the present invention. Fig.13 As shown, the device comprises:

[0124] The parameter detection module 1302 is used to obtain the fault type and the current first power parameter of the preset coupling point in the distribution network in response to a fault in the distribution network.

[0125] The parameter acquisition module 1304 is used to obtain a second power parameter from the power parameter table based on the coupling point identifier of the preset coupling point, wherein the power parameter table is used to store the power parameters of the preset coupling point at different times, and the second power parameter is used to characterize the power parameter of the preset coupling point at a moment before a fault occurs in the distribution network.

[0126] The current calculation module 1306 is used to determine the closed-loop impact current of the distribution network based on the fault type, the first power parameter and the second power parameter, wherein the closed-loop impact current is used to characterize the impact current generated when the distribution network is closed-loop operated.

[0127] Furthermore, the current calculation module is also used to: determine the change in power parameters of the distribution network when a fault occurs based on the first power parameter and the second power parameter; determine the equivalent resistance of the distribution network based on the fault type and the change in power parameters; determine the open circuit voltage of the distribution network based on the fault type, the equivalent resistance and the second power parameter; determine the closed-loop impact current based on the equivalent resistance, the open-circuit voltage and the attenuation time constant, wherein the attenuation time constant is used to reflect the process from transient to steady state of the current generated by the distribution network when performing a closed-loop operation.

[0128] Furthermore, the first power parameter includes: a first voltage and a first current at a preset coupling point when a fault occurs in the distribution network, the second power parameter includes: a second voltage and a second current at the preset coupling point at a moment before the fault occurs in the distribution network, and the power parameter change includes: a voltage change and a current change; the current calculation module is also used to: obtain a voltage change based on the difference between the first voltage and the second voltage; and obtain a current change based on the difference between the first current and the second current.

[0129] Furthermore, the fault types include system load fluctuations and system power supply fluctuations, and the current calculation module is also used to: obtain the initial resistance based on the ratio of the voltage change and the current change in the power parameter change; in response to the fault type being system load fluctuations, determine the initial resistance as an equivalent resistance; in response to the fault type being system power supply fluctuations, obtain the system internal resistance of the distribution network, and obtain the first resistance based on the product of the initial resistance and the equivalent resistance, obtain the second resistance based on the sum of the initial resistance and the system content, and obtain the equivalent resistance based on the quotient of the first resistance and the second resistance.

[0130] Furthermore, the current calculation module is also used to: in response to the fault type being system load fluctuation, obtain a third voltage based on the product of the first current and the equivalent current in the first power parameter; and obtain an open circuit voltage based on the difference between the first voltage and the third voltage in the first power parameter.

[0131] Furthermore, the current calculation module is also used to: in response to the fault type being system power supply fluctuation, obtain the system voltage of the distribution network; obtain the first electric power based on the product of the first voltage in the first power parameter and the system internal resistance, and obtain the second electric power based on the product of the system voltage and the initial resistance; obtain the target resistance based on the sum of the initial resistance and the system resistance, and obtain the third electric power based on the sum of the first electric power and the second electric power; obtain the open circuit voltage based on the quotient of the third electric power and the target resistance.

[0132] Furthermore, the open circuit voltage includes a first open circuit voltage and a second open circuit voltage at both ends of the closing point in the distribution network, and the equivalent resistance includes a first equivalent resistance and a second equivalent resistance at both ends of the closing point; the current calculation module is also used to: obtain a third open circuit voltage based on the difference between the first open circuit voltage and the second open circuit voltage, and obtain a third equivalent resistance based on the sum of the first equivalent resistance and the second equivalent resistance; obtain a closed-loop steady-state current of the distribution network based on the quotient of the third open circuit voltage and the third equivalent resistance, wherein the closed-loop steady-state current is used to characterize the current generated after the distribution network is closed-loop operated; construct a current attenuation coefficient based on the attenuation time constant and the preset constant; and obtain a closed-loop impact current based on the product of the closed-loop steady-state current and the current attenuation coefficient.

[0133] Furthermore, the device also includes: a first acquisition module, used to acquire the system frequency of the distribution network; a first determination module, used to determine the specific frequency of the distribution network according to a preset frequency function based on the system frequency, wherein the accuracy of the distribution network in describing the attenuation process of the closed-loop impulse current at the specific frequency is higher than the accuracy of the distribution network in describing the attenuation process of the closed-loop impulse current at other frequencies; a second determination module, used to determine the target impedance corresponding to the specific frequency based on the system frequency and the specific frequency according to a preset impedance function; and a third determination module, used to determine the attenuation time constant based on the target impedance and the specific frequency according to a preset time function.

[0134] Furthermore, the device also includes: a second acquisition module, used to acquire a current threshold of a distribution network protection device, wherein the distribution network protection device is used to control the distribution network to stop power supply when the closing-loop impact current is greater than the current threshold; a first control module, used to control the distribution network to perform a closing-loop operation in response to the closing-loop impact current being less than or equal to the current threshold; and a second control module, used to adjust the operating state of a load device in the distribution network based on the closing-loop impact current in response to the closing-loop impact current being greater than the current threshold, so as to control the closing-loop impact current to be less than or equal to the current threshold.

[0135] An embodiment of the present application further provides an electronic device, comprising: a memory storing an executable program; and a processor for running the program, wherein the program executes the methods in various embodiments of the present invention when running.

[0136] An embodiment of the present application further provides a computer-readable storage medium, which includes a stored executable program, wherein when the executable program is running, the device where the computer-readable storage medium is located is controlled to execute the methods in various embodiments of the present invention.

[0137] An embodiment of the present application further provides a computer program product, including a computer program, which implements the methods in various embodiments of the present invention when executed by a processor.

[0138] An embodiment of the present application further provides a computer program product, including a non-volatile computer-readable storage medium, wherein the non-volatile computer-readable storage medium is used to store a computer program, and when the computer program is executed by a processor, the method in each embodiment of the present invention is implemented.

[0139] The embodiments of the present application further provide a computer program, which implements the methods in the above-mentioned embodiments of the present invention when executed by a processor.

[0140] In the above embodiments of the present invention, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0141] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. Among them, the device embodiments described above are only schematic. For example, the division of the units can be a logical function division. There may be other division methods in actual implementation. For example, multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be through some interfaces, indirect coupling or communication connection of units or modules, which can be electrical or other forms.

[0142] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple units. Some or all of the units may be selected according to actual needs to achieve the purpose of the present embodiment.

[0143] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit. The above-mentioned integrated unit may be implemented in the form of hardware or in the form of software functional units.

[0144] If the integrated unit is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions for a computer device (which can be a personal computer, a server or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present invention. The aforementioned storage medium includes: U disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), mobile hard disk, magnetic disk or optical disk and other media that can store program codes.

[0145] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for calculating the closed-loop impulse current of a distribution network, characterized in that: include: In response to a fault in the distribution network, obtaining a fault type of the fault and a current first power parameter of a preset coupling point in the distribution network; Based on the coupling point identifier of the preset coupling point, obtaining a second power parameter from a power parameter table, wherein the power parameter table is used to store the power parameters of the preset coupling point at different times, and the second power parameter is used to characterize the power parameter of the preset coupling point at a time before the failure of the distribution network occurs; Based on the fault type, the first power parameter and the second power parameter, a closed-loop impact current of the distribution network is determined, wherein the closed-loop impact current is used to characterize an impact current generated when a closed-loop operation is performed on the distribution network.

2. The method according to claim 1, characterized in that Determining a closed-loop inrush current of the distribution network based on the fault type, the first power parameter, and the second power parameter includes: Based on the first power parameter and the second power parameter, determining a power parameter change amount of the distribution network when a fault occurs; Determining an equivalent resistance of the distribution network based on the fault type and the power parameter change; Determining an open circuit voltage of the distribution network based on the fault type, the equivalent resistance and the second power parameter; The closed-loop impact current is determined based on the equivalent resistance, the open-circuit voltage and the decay time constant, wherein the decay time constant is used to reflect the process of the current generated by the distribution network during the closed-loop operation from transient to steady state.

3. The method according to claim 2, characterized in that The first power parameter includes: a first voltage and a first current of the preset coupling point when the distribution network fails, the second power parameter includes: a second voltage and a second current of the preset coupling point at a moment before the distribution network fails, and the power parameter change includes: a voltage change and a current change; based on the first power parameter and the second power parameter, determining the power parameter change of the distribution network when the fault occurs includes: Obtaining the voltage variation based on a difference between the first voltage and the second voltage; The current variation is obtained based on a difference between the first current and the second current.

4. The method according to claim 2, characterized in that: The fault type includes system load fluctuation and system power supply fluctuation. Based on the fault type and the power parameter change, determining the equivalent resistance of the distribution network includes: Based on the ratio of the voltage change to the current change in the power parameter change, an initial resistance is obtained; In response to the fault type being the system load fluctuation, determining the initial resistance to be the equivalent resistance; In response to the fault type being the system power supply fluctuation, the system internal resistance of the distribution network is obtained, and a first resistance is obtained based on the product of the initial resistance and the equivalent resistance, a second resistance is obtained based on the sum of the initial resistance and the system content, and the equivalent resistance is obtained based on the quotient of the first resistance and the second resistance.

5. The method according to claim 4, characterized in that Determining an open circuit voltage of the distribution network based on the fault type, the equivalent resistance and the second power parameter includes: In response to the fault type being the system load fluctuation, obtaining a third voltage based on the product of the first current in the first power parameter and the equivalent current; The open circuit voltage is obtained based on a difference between a first voltage and a third voltage in the first power parameter.

6. The method according to claim 5, characterized in that Determining an open circuit voltage of the distribution network based on the fault type, the equivalent resistance and the second power parameter includes: In response to the fault type being the system power supply fluctuation, obtaining the system voltage of the distribution network; Obtaining a first electric power based on the product of a first voltage in the first power parameter and the system internal resistance, and obtaining a second electric power based on the product of the system voltage and the initial resistance; obtaining a target resistance based on a sum of the initial resistance and the system resistance, and obtaining a third electric power based on a sum of the first electric power and the second electric power; The open circuit voltage is obtained based on a quotient of the third electric power and the target resistance.

7. The method according to claim 2, characterized in that The open circuit voltage includes a first open circuit voltage and a second open circuit voltage at both ends of the closing point in the distribution network, and the equivalent resistance includes a first equivalent resistance and a second equivalent resistance at both ends of the closing point; and determining the closing impulse current based on the equivalent resistance, the open circuit voltage and the attenuation time constant includes: Obtaining a third open circuit voltage based on a difference between the first open circuit voltage and the second open circuit voltage, and obtaining a third equivalent resistance based on a sum of the first equivalent resistance and the second equivalent resistance; Based on the quotient of the third open-circuit voltage and the third equivalent resistance, a closed-loop steady-state current of the distribution network is obtained, wherein the closed-loop steady-state current is used to characterize the current generated after the distribution network is closed-loop operated; Based on the decay time constant and the preset constant, a current decay coefficient is constructed; The closed-loop impact current is obtained based on the product of the closed-loop steady-state current and the current attenuation coefficient.

8. The method according to claim 2, characterized in that: The method further comprises: Obtaining a system frequency of the power distribution network; Based on the system frequency, determining the specific frequency of the distribution network according to a preset frequency function, wherein the accuracy of the distribution network in describing the attenuation process of the closed-loop impulse current at the specific frequency is higher than the accuracy of the distribution network in describing the attenuation process of the closed-loop impulse current at other frequencies; According to a preset impedance function, determining a target impedance corresponding to the specific frequency based on the system frequency and the specific frequency; The decay time constant is determined based on the target impedance and the specific frequency according to a preset time function.

9. The method according to claim 1, characterized in that: The method further comprises: Acquiring a current threshold of the distribution network protection device, wherein the distribution network protection device is used to control the distribution network to stop supplying power when the closed-loop impact current is greater than the current threshold; In response to the closing-loop impact current being less than or equal to the current threshold, controlling the distribution network to perform a closing-loop operation; In response to the closed-loop impact current being greater than the current threshold, the operating state of the load device in the distribution network is adjusted based on the closed-loop impact current to control the closed-loop impact current to be less than or equal to the current threshold.

10. A device for calculating the closed-loop impulse current of a distribution network, characterized in that: include: A parameter detection module, configured to obtain, in response to a fault in the distribution network, a fault type of the fault and a current first power parameter of a preset coupling point in the distribution network; a parameter acquisition module, configured to acquire a second power parameter from a power parameter table based on a coupling point identifier of the preset coupling point, wherein the power parameter table is used to store the power parameters of the preset coupling point at different times, and the second power parameter is used to characterize the power parameter of the preset coupling point at a time before a fault occurs in the distribution network; A current calculation module is used to determine the closed-loop impact current of the distribution network based on the fault type, the first power parameter and the second power parameter, wherein the closed-loop impact current is used to characterize the impact current generated when the distribution network is closed-loop operated.

11. The device according to claim 10, characterized in that The current calculation module is also used for: Based on the first power parameter and the second power parameter, determining a power parameter change amount of the distribution network when a fault occurs; Determining an equivalent resistance of the distribution network based on the fault type and the power parameter change; Determining an open circuit voltage of the distribution network based on the fault type, the equivalent resistance and the second power parameter; The closed-loop impact current is determined based on the equivalent resistance, the open-circuit voltage and the decay time constant, wherein the decay time constant is used to reflect the process of the current generated by the distribution network during the closed-loop operation from transient to steady state.

12. The device according to claim 11, characterized in that The first power parameter includes: a first voltage and a first current of the preset coupling point when the distribution network fails; the second power parameter includes: a second voltage and a second current of the preset coupling point at a moment before the distribution network fails; the power parameter variation includes: a voltage variation and a current variation; the current calculation module is further used to: Obtaining the voltage variation based on a difference between the first voltage and the second voltage; The current variation is obtained based on a difference between the first current and the second current.

13. The device according to claim 11, characterized in that The fault types include system load fluctuation and system power supply fluctuation, and the current calculation module is further used for: Based on the ratio of the voltage change to the current change in the power parameter change, an initial resistance is obtained; In response to the fault type being the system load fluctuation, determining the initial resistance to be the equivalent resistance; In response to the fault type being the system power supply fluctuation, the system internal resistance of the distribution network is obtained, and a first resistance is obtained based on the product of the initial resistance and the equivalent resistance, a second resistance is obtained based on the sum of the initial resistance and the system content, and the equivalent resistance is obtained based on the quotient of the first resistance and the second resistance.

14. The device according to claim 13, characterized in that The current calculation module is also used for: In response to the fault type being the system load fluctuation, obtaining a third voltage based on the product of the first current in the first power parameter and the equivalent current; The open circuit voltage is obtained based on a difference between a first voltage and a third voltage in the first power parameter.

15. The device according to claim 14, characterized in that The current calculation module is also used for: In response to the fault type being the system power supply fluctuation, obtaining the system voltage of the distribution network; Obtaining a first electric power based on the product of a first voltage in the first power parameter and the system internal resistance, and obtaining a second electric power based on the product of the system voltage and the initial resistance; obtaining a target resistance based on a sum of the initial resistance and the system resistance, and obtaining a third electric power based on a sum of the first electric power and the second electric power; The open circuit voltage is obtained based on a quotient of the third electric power and the target resistance.

16. The device according to claim 11, characterized in that The open circuit voltage includes a first open circuit voltage and a second open circuit voltage at both ends of the closing point in the distribution network, and the equivalent resistance includes a first equivalent resistance and a second equivalent resistance at both ends of the closing point; the current calculation module is also used for: Obtaining a third open circuit voltage based on a difference between the first open circuit voltage and the second open circuit voltage, and obtaining a third equivalent resistance based on a sum of the first equivalent resistance and the second equivalent resistance; Based on the quotient of the third open-circuit voltage and the third equivalent resistance, a closed-loop steady-state current of the distribution network is obtained, wherein the closed-loop steady-state current is used to characterize the current generated after the distribution network is closed-loop operated; Based on the decay time constant and the preset constant, a current decay coefficient is constructed; The closed-loop impact current is obtained based on the product of the closed-loop steady-state current and the current attenuation coefficient.

17. The device according to claim 11, characterized in that The device also includes: A first acquisition module, used to acquire the system frequency of the power distribution network; A first determination module determines a specific frequency of the distribution network according to a preset frequency function based on the system frequency, wherein the accuracy of the distribution network in describing the attenuation process of the closed-loop impulse current at the specific frequency is higher than the accuracy of the distribution network in describing the attenuation process of the closed-loop impulse current at other frequencies; A second determination module, configured to determine a target impedance corresponding to the specific frequency based on the system frequency and the specific frequency according to a preset impedance function; The third determination module determines the attenuation time constant based on the target impedance and the specific frequency according to a preset time function.

18. The device according to claim 10, characterized in that The device also includes: A second acquisition module is used to acquire a current threshold of the distribution network protection device, wherein the distribution network protection device is used to control the distribution network to stop supplying power when the closed-loop impact current is greater than the current threshold; A first control module, configured to control the distribution network to perform a loop closing operation in response to the loop closing impact current being less than or equal to the current threshold; The second control module is used to adjust the operating state of the load device in the distribution network based on the closed-loop impact current in response to the closed-loop impact current being greater than the current threshold, so as to control the closed-loop impact current to be less than or equal to the current threshold.

19. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored executable program, wherein when the executable program is executed, the device where the storage medium is located is controlled to execute the method according to any one of claims 1 to 9.

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