Current protection setting constant value self-adaptive setting method, device, equipment and medium

Abstract

The invention relates to the technical field of intelligent power grids, in particular to a current protection setting constant value adaptive setting method, device and equipment and a medium, and the method comprises the steps: obtaining a three-phase voltage instantaneous value and a three-phase current instantaneous value at a protection point when a fault of a line is detected; calculating a positive sequence voltage, a positive sequence current and a negative sequence current at the protection point according to the three-phase voltage instantaneous value and the three-phase current instantaneous value; judging a fault type according to the negative sequence current; if the fault type is a two-phase short-circuit fault, calculating according to a first adaptive setting formula to obtain a first current protection setting value; if the fault type is a three-phase short-circuit fault, calculating according to a second adaptive setting formula to obtain a second current protection setting value; and according to the first current protection setting value or the second current protection setting value, executing a corresponding overcurrent protection action on the power distribution network, thereby solving the problem that the fault type is difficult to accurately identify due to failure of the fault current proportional relation caused by the access of the distributed power supply.

Description

Technical Field

[0001] This invention relates to the field of smart grid technology, and in particular to an adaptive setting method, device, equipment and medium for current protection setting. Background Technology

[0002] In recent years, with the advancement of the national "dual-carbon" goals and the development of new energy grid-connection technologies, the content of distributed generation in distribution networks has been increasing. After the integration of distributed generation, the distribution network transforms from a single-source radial power supply network into a multi-source structure, which can easily alter the magnitude and direction of fault currents during faults. For current protection in distribution networks, on the one hand, the integration of distributed generation changes the overall impedance of the system, leading to significant changes in fault characteristics; on the other hand, due to the influence of distributed generation control strategies, the relationship between two-phase short-circuit fault currents and three-phase short-circuit fault currents is no longer fixed. As the number and capacity of distributed generation sources increase, the impact on protection becomes more significant, and the different locations and capacities of distributed generation sources make it difficult to adapt the protection settings at various points in the distribution network to the system's operating characteristics. Summary of the Invention

[0003] Based on this, it is necessary to propose an adaptive setting method for current protection settings to address the technical problem that the protection settings of existing technologies are difficult to adapt to the operating characteristics of the system.

[0004] Firstly, an adaptive setting method for current protection setting values ​​is provided, the method comprising: When a line fault is detected, the instantaneous values ​​of the three-phase voltage and the three-phase current at the protection point are obtained; Based on the instantaneous values ​​of the three-phase voltage and the instantaneous values ​​of the three-phase current, calculate the positive sequence voltage, positive sequence current, and negative sequence current at the protection point; The fault type is determined based on the negative sequence current. If the fault type is a two-phase short-circuit fault, the first current protection setting value is calculated according to the first adaptive setting formula; the input of the first adaptive setting formula includes at least: the positive sequence voltage, the system comprehensive impedance, the impedance of the line where the protection installation point is located, the impedance from the protection installation point to the upstream bus, and the sum of the output currents provided by all distributed power sources located downstream of the protection installation point; If the fault type is a three-phase short-circuit fault, the second current protection setting value is calculated according to the second adaptive setting formula; the input of the second adaptive setting formula includes at least: the positive sequence voltage and the impedance of this segment; Based on the first current protection setting value or the second current protection setting value, the corresponding overcurrent protection action is performed on the distribution network.

[0005] Preferably, the overall system impedance is obtained by dividing the negative sequence voltage measured at the protection point by the negative sequence current at the fault location.

[0006] Preferably, the step of calculating the positive-sequence voltage, positive-sequence current, and negative-sequence current at the protection point based on the instantaneous values ​​of the three-phase voltage and the instantaneous values ​​of the three-phase current includes: Obtain the rotating operator, as well as the instantaneous values ​​of the three-phase currents and voltages of phases A, B, and C; The phase B voltage and phase C voltage are rotated by 120° and 240° respectively by the rotation operator so that they are in phase with phase A voltage. The positive sequence voltage is obtained by averaging the instantaneous values ​​of the three phase voltages A, B and C after the phase rotation. The phase B current and phase C current are rotated by 120° and 240° respectively by the rotation operator so that they are in the same phase as phase A current. The positive sequence current is obtained by taking the average value of the instantaneous values ​​of the three phase currents A, B and C after the phase rotation. The phase B current and the phase C current are rotated by 240° and 120° respectively by the rotation operator so that they are in the same phase as the phase A current. The negative sequence current is obtained by taking the average value of the instantaneous values ​​of the three phase currents A, B and C after the phase rotation.

[0007] Preferably, the expression for the first adaptive tuning formula is: This is the setting value for the first current protection. It is a positive sequence voltage; The overall impedance of the system; Protect the impedance of this section of the line where the installation point is located; Protect the impedance from the installation point to the upstream busbar; The sum of the output currents provided by all distributed power sources located downstream of the protection installation point.

[0008] Preferably, the second adaptive tuning formula is: in This is the setting value for the second current protection. It is a positive sequence voltage. Protect the impedance of this section of the line where the installation point is located.

[0009] Preferably, the step of performing corresponding overcurrent protection actions on the distribution network according to the first current protection setting value or the second current protection setting value includes: Compare the first current protection setting value or the second current protection setting value with the fault current at the protection point; If the current is less than the fault current, a delayed trip will be initiated. If the fault current is not less than the stated fault current, the tripping function will be initiated immediately.

[0010] Preferably, the step of initiating a delayed trip if the fault current is greater than the fault current includes: If the first current protection setting value or the second current protection setting value is greater than the fault current at the protection point; Reacquire the relevant data to calculate the first current protection setting value or the second current protection setting value; If, within the predetermined time, the recalculated first current protection setting value or the second current protection setting value is not greater than the fault current, then the tripping will be initiated immediately. If the predetermined time is reached, regardless of whether the first current protection setting value or the second current protection setting value is greater than the fault current, the tripping will be initiated immediately.

[0011] A second aspect of this application provides a current protection setting adaptive setting device, the device comprising: The fault identification module is used to acquire and determine in real time whether the three-phase current at the protection point is abnormal. If so, obtain the three-phase current value at the protection point, and calculate the positive sequence current and negative sequence current at the protection point based on the three-phase current; The fault type determination module is used to determine the fault type based on the characteristics of the positive sequence current and negative sequence current at the protection point. If it is determined to be a two-phase short circuit, obtain the reliability coefficient of the two-phase short circuit current protection, the output current value of the distributed power source, the two-phase short circuit current protection coefficient, the positive sequence voltage at the protection point, the system comprehensive impedance, the fault line impedance, and the impedance from the fault point to the bus, and calculate the two-phase short circuit adaptive setting value. If it is determined to be a three-phase short circuit, obtain the three-phase short circuit current protection coefficient, the positive sequence voltage at the protection point and the fault line impedance, and calculate the three-phase short circuit adaptive setting value. The protection action issuing module is used to make protection actions based on the two-phase short-circuit adaptive setting value or the three-phase short-circuit adaptive setting value.

[0012] A third aspect of this application provides a computer device, the computer device including a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor executes the computer program to implement the steps of the current protection setting adaptive setting method as described in any of the preceding claims.

[0013] A fourth aspect of this application provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps of adaptive setting of the current protection setting value as described in any of the preceding claims.

[0014] Beneficial effects: The technical solution disclosed in this application can accurately determine the fault type by acquiring the instantaneous values ​​of three-phase voltage and current at the protection point of the faulty line in real time and calculating key sequence components such as positive-sequence voltage, positive-sequence current, and negative-sequence current. In particular, it effectively distinguishes between two-phase short circuits and three-phase short circuits based on the characteristics of negative-sequence current, solving the problem of difficult fault identification caused by the failure of traditional fault current ratio relationships in distributed power supply scenarios. This application designs differentiated adaptive setting strategies for different fault types: for two-phase short circuit faults, the first adaptive setting formula comprehensively incorporates multiple real-time parameters such as positive-sequence voltage, system comprehensive impedance, line impedance, and the contribution of downstream distributed power supply fault current to dynamically generate protection setting values ​​that match the characteristics of this type of asymmetrical fault; for three-phase short circuit faults, the second adaptive setting formula adaptively generates setting values ​​suitable for symmetrical faults based on key parameters such as positive-sequence voltage and line impedance. Ultimately, protection actions are executed based on the adaptively generated setting values, thereby enabling dynamic adjustment of current protection setting values ​​for different fault types in complex distribution network environments with widespread distributed power source integration, according to system status and fault characteristics. This significantly improves the adaptability, selectivity, and reliability of the protection, effectively avoiding the maloperation or failure to operate problems that easily occur in traditional fixed-setting protection methods under the influence of system impedance changes and distributed power sources. This application utilizes the characteristic differences between positive-sequence and negative-sequence currents to accurately distinguish between two-phase short circuits and three-phase short circuits, providing a key judgment basis for differentiated setting and solving the problem of difficulty in accurately identifying fault types due to the failure of the fault current ratio relationship caused by the integration of distributed power sources. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] in: Figure 1 This is a diagram illustrating the application environment of the adaptive setting method for current protection settings in one embodiment. Figure 2 This is a flowchart of an adaptive setting method for current protection setting values ​​in one embodiment; Figure 3This is a diagram of a distribution network structure with distributed power source access in one embodiment; Figure 4 This is a positive sequence network diagram for a two-phase short-circuit fault at point f in one embodiment; Figure 5 This is a negative sequence network diagram for a two-phase short-circuit fault at point f in one embodiment; Figure 6 This is a composite network diagram for a two-phase short-circuit fault at point f in one embodiment; Figure 7 This is a structural block diagram of a current protection setting adaptive setting device in one embodiment; Figure 8 This is a structural block diagram of a computer device in one embodiment. Detailed Implementation

[0017] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] The adaptive current protection setting method provided in this invention can be applied to applications such as... Figure 1In this application environment, the user terminal communicates with the server terminal via a network. The server terminal can achieve the following through the application terminal: When a line fault is detected, it obtains the instantaneous values ​​of the three-phase voltage and three-phase current at the protection point; based on these values, it calculates the positive-sequence voltage, positive-sequence current, and negative-sequence current at the protection point; it determines the fault type based on the negative-sequence current; if the fault type is a two-phase short-circuit fault, it calculates the first current protection setting value according to the first adaptive setting formula; the inputs to the first adaptive setting formula include at least: positive-sequence voltage, system comprehensive impedance, impedance of the line segment where the protection installation point is located, impedance from the protection installation point to the upstream bus, and the sum of the output currents provided by all distributed power sources downstream of the protection installation point; if the fault type is a three-phase short-circuit fault, it calculates the second current protection setting value according to the second adaptive setting formula; the inputs to the second adaptive setting formula include at least: positive-sequence voltage and impedance of the current segment; based on the first or second current protection setting value, it executes the corresponding overcurrent protection action on the distribution network and transmits the overcurrent protection action to the application terminal. This application addresses the complexities of power distribution networks by utilizing the differences in positive-sequence and negative-sequence current characteristics to accurately distinguish between two-phase and three-phase short circuits. This provides a crucial basis for differentiated setting and solves the problem of accurately identifying fault types due to the failure of fault current ratio relationships caused by the integration of distributed power sources. The application can be, but is not limited to, various power grid devices such as protection devices, circuit breakers, transformers, and distributed power sources. The server can be implemented using a standalone server or a server cluster composed of multiple servers. The invention will be described in detail below through specific embodiments.

[0019] Please see Figure 2 As shown, Figure 2 A flowchart illustrating the adaptive setting method for current protection setting provided in this embodiment of the invention includes the following steps: S1: When a line fault is detected, obtain the instantaneous values ​​of the three-phase voltage and the three-phase current at the protection point.

[0020] Specifically, a protection point refers to the exact location where a current protection device is installed in a distribution network, typically at the circuit breaker at the beginning of the line (busbar side). This point is the measurement point of the protection device and also the starting point of its protection range. Three-phase current refers to the power frequency AC current flowing through the three-phase (A-phase, B-phase, C-phase) line corresponding to the protection point. Under normal operating conditions, the three-phase currents are essentially symmetrical (with similar amplitudes and a phase difference of 120°).

[0021] This application uses high-speed data acquisition and real-time calculation to determine whether the three-phase current is abnormal. It can accurately capture abnormal changes in current within the first or several power frequency cycles after a fault occurs (usually within 20-40 milliseconds), thus gaining critical time for rapid fault clearing.

[0022] Specifically, the fundamental phasor data of the three-phase current, which were collected and preprocessed (such as filtering and A / D conversion) within one or more cycles before and after the fault occurred, are extracted from the data buffer or register of the protection point device. These data are usually represented in complex form (amplitude and phase, or real and imaginary parts).

[0023] S2: Calculate the positive sequence voltage, positive sequence current and negative sequence current at the protection point based on the instantaneous values ​​of the three-phase voltage and the three-phase current.

[0024] Specifically, the instantaneous value of three-phase voltage refers to the instantaneous sampled value of the three-phase voltages A, B, and C at the protection point as a function of time; the instantaneous value of three-phase current refers to the instantaneous sampled value of the three-phase currents A, B, and C at the protection point as a function of time.

[0025] Positive-sequence current refers to a symmetrical three-phase current system with equal amplitudes and phases that lag each other by 120 degrees in an ABC sequence. It reflects the component of the fault current that is in the same phase sequence as the normal power supply and is a key indicator of the severity of the fault.

[0026] Negative-sequence current refers to a set of symmetrical three-phase current systems with equal amplitudes but phases that lag by 120 degrees in the ACB sequence (opposite to the positive sequence). It is a direct characteristic signal of an asymmetrical fault (such as a two-phase short circuit) in the system.

[0027] This step provides fault detection and data acquisition functions, providing the foundation of raw electrical quantity data for subsequent analysis.

[0028] In some implementations, the fault identification method may be to confirm a fault by determining that the instantaneous current or voltage value changes by more than a set threshold within a certain period of time. Alternatively, after the fault is detected for the first time, a time delay, such as 1 to 10 ms, is applied. If the fault signal persists during this delay, it is confirmed that a fault has indeed occurred and is not an occasional line fluctuation or abnormal data acquisition.

[0029] S3: Determine the fault type based on the negative sequence current.

[0030] Specifically, the judgment method is usually as follows: determine whether the negative sequence current at the protection point is greater than the rated current of the protection device; if yes, it is judged as a two-phase fault; otherwise, it is judged as a three-phase fault. The rated current of the protection device refers to the maximum continuous operating current allowed to pass through the power line (or electrical equipment) it is designed to protect under long-term normal operating conditions. It is the reference current value for parameter setting and functional configuration of the protection device and is determined during installation. Based on the calculated amplitude characteristics of the negative sequence current, a logical judgment is made by comparing it with a preset threshold (such as the negative sequence current initiation threshold) to quickly and accurately distinguish the fault type. It can accurately identify fault types such as three-phase short circuits and two-phase short circuits, providing the correct formula selection basis for subsequent adaptive setting calculations. This judgment mechanism does not rely on the fixed current ratio relationship in the traditional power grid, thus effectively adapting to the changes in fault characteristics after the integration of distributed power sources, ensuring that the protection setting accurately matches the actual fault situation, and improving the reliability and selectivity of the protection from the source.

[0031] S4: If the fault type is a two-phase short circuit fault, the first current protection setting value is calculated according to the first adaptive setting formula. The input of the first adaptive setting formula includes at least: positive sequence voltage, system comprehensive impedance, impedance of the line where the protection installation point is located, impedance from the protection installation point to the upstream bus, and the sum of the output currents provided by all distributed power sources located downstream of the protection installation point.

[0032] Specifically, positive sequence voltage refers to the positive sequence voltage component measured at the protection installation point (busbar) after a fault occurs. Its magnitude directly reflects the electrical distance to the fault point and the system's voltage support capability: the closer the fault or the weaker the system, the more severe the voltage drop. The first adaptive setting formula is the mathematical expression used to calculate the current protection setting value during a two-phase short-circuit fault. The system comprehensive impedance is the equivalent impedance viewed from the protection installation point towards the system side. The impedance of the line segment where the protection installation point is located refers to the impedance of the line segment where the protection installation point is located. The impedance from the protection installation point to the upstream busbar refers to the line impedance between the protection installation point and the upstream busbar.

[0033] The sum of output currents provided by distributed generation sources refers to the total output current value of all distributed generation sources downstream of the protection installation point. It represents the sum of the short-circuit currents injected into the fault point by each distributed generation source downstream of the fault point (such as photovoltaic inverters and wind turbine converters) during a fault. Its function is to add a safety margin to the theoretically calculated minimum operating current, to "avoid" various possible errors (such as measurement errors, calculation errors, system parameter fluctuations, etc.), ensuring reliable protection operation even under the most unfavorable conditions and avoiding failure to operate. This value is limited by the fault ride-through control strategy of the distributed generation sources and is usually no more than twice their rated current, fundamentally different from the fault current characteristics of traditional synchronous power sources.

[0034] The system composite impedance refers to the equivalent positive-sequence impedance viewed from the protection installation point towards the system power source side. It comprehensively reflects the "strength" of the fault point from the main power grid, upstream transformers, and other power sources operating in parallel (including some distributed power sources). It is a key dynamic parameter for calculating short-circuit current.

[0035] When a two-phase short-circuit fault is detected in the system, the first adaptive setting formula is immediately invoked. Key parameters are first retrieved from the system database or real-time calculations: positive sequence voltage, system composite impedance, impedance of the line segment where the protection installation point is located, impedance from the protection installation point to the upstream bus, and the sum of the output currents provided by all distributed power sources downstream of the protection installation point. Then, these parameters are substituted into the formula to calculate in real-time the two-phase short-circuit adaptive setting value that precisely matches the current fault location, system operating status, and DG output.

[0036] S5: If the fault type is a three-phase short-circuit fault, the second current protection setting value is calculated according to the second adaptive setting formula; the input of the second adaptive setting formula includes at least: positive sequence voltage and current impedance.

[0037] Specifically, the three-phase short-circuit adaptive setting value refers to the dynamic operating current threshold value specifically calculated for three-phase short-circuit faults. When the system is identified as having a three-phase short-circuit fault, the second adaptive setting formula activates the symmetrical fault setting model. Its core calculation formula obtains key parameters: the positive sequence voltage at the protection point (the bus positive sequence voltage measured in real time during a fault, directly reflecting the voltage drop depth caused by the fault) and the impedance of the line segment where the protection installation point is located. Subsequently, these dynamic parameters are substituted into the formula to calculate the three-phase short-circuit adaptive setting value in real time.

[0038] This system enables rapid and adaptive threshold setting for the most severe symmetrical faults. By introducing real-time positive-sequence voltage (instead of a preset fixed voltage) and online identification of the impedance of the line segment where the protection installation point is located, the setting value accurately reflects the actual short-circuit capacity and electrical distance of the current system. This allows the protection setting to dynamically adjust according to the system operating mode (especially the switching and output changes of distributed power sources) and the fault location. Thus, in the event of a three-phase short circuit, it can ensure rapid clearing of near-end faults (sensitivity) while reliably avoiding far-end faults or normal load currents (selectivity). This effectively solves the problem that traditional settings are prone to false tripping or failure to trip when system impedance changes, significantly improving the adaptability and reliability of the distribution network for severe symmetrical faults.

[0039] S6: Perform corresponding overcurrent protection actions on the distribution network according to the first current protection setting value or the second current protection setting value.

[0040] Specifically, the dynamically calculated setting value that best matches the current fault type and system state is used as the sole threshold for action, ensuring the real-time optimality of the action current criterion. The protection action command is then transmitted to the corresponding device to execute the trip operation.

[0041] This application utilizes the characteristic differences between positive-sequence and negative-sequence currents to accurately distinguish between two-phase short circuits and three-phase short circuits, providing a key basis for differentiated setting and solving the problem of difficulty in accurately identifying fault types due to the failure of the fault current ratio relationship caused by the access of distributed power sources.

[0042] In some implementations, the system composite impedance is obtained by proportionally dividing the negative-sequence voltage at the fault point by the negative-sequence current at the fault point. The specific formula is as follows: in For the overall system impedance, The negative sequence voltage at the fault point. This is the negative sequence current at the fault point.

[0043] The technical solution disclosed in this embodiment can accurately determine the fault type by acquiring the instantaneous values ​​of three-phase voltage and current at the protection point of the faulty line in real time and calculating key sequence components such as positive-sequence voltage, positive-sequence current, and negative-sequence current. In particular, it effectively distinguishes between two-phase short circuits and three-phase short circuits based on the characteristics of negative-sequence current, solving the problem of difficulty in fault identification caused by the failure of traditional fault current ratio relationships in distributed power supply scenarios. This application designs differentiated adaptive setting strategies for different fault types: for two-phase short circuit faults, the first adaptive setting formula comprehensively incorporates multiple real-time parameters such as positive-sequence voltage, system comprehensive impedance, line impedance, and the contribution of downstream distributed power supply fault current to dynamically generate protection setting values ​​that match the characteristics of this type of asymmetrical fault; for three-phase short circuit faults, the second adaptive setting formula adaptively generates setting values ​​suitable for symmetrical faults based on key parameters such as positive-sequence voltage and line impedance. Ultimately, protection actions are executed based on the adaptively generated setting values, thereby enabling dynamic adjustment of current protection setting values ​​for different fault types in complex distribution network environments with widespread distributed power source integration, according to system status and fault characteristics. This significantly improves the adaptability, selectivity, and reliability of the protection, effectively avoiding the maloperation or failure to operate problems that easily occur in traditional fixed-setting protection methods under the influence of system impedance changes and distributed power sources. This application utilizes the characteristic differences between positive-sequence and negative-sequence currents to accurately distinguish between two-phase short circuits and three-phase short circuits, providing a key judgment basis for differentiated setting and solving the problem of difficulty in accurately identifying fault types due to the failure of the fault current ratio relationship caused by the integration of distributed power sources.

[0044] In some implementations, step S2 includes: S21: Obtain the rotating operator, as well as the instantaneous values ​​of the three-phase currents and voltages of phases A, B, and C.

[0045] S22: By using the rotation operator, the phase B voltage and phase C voltage are rotated by 120° and 240° respectively, so that they are in the same phase as the phase A voltage. Based on the instantaneous values ​​of the three phase voltages A, B and C after phase rotation, the average value is taken to obtain the positive sequence voltage.

[0046] S23: By using the rotation operator, the phase B current and phase C current are rotated by 120° and 240° respectively, so that they are in the same phase as the phase A current. Based on the instantaneous values ​​of the three phase currents A, B and C after the phase rotation, the average value is taken to obtain the positive sequence current.

[0047] S24: By using a rotation operator, the phase B current and phase C current are rotated by 240° and 120° respectively, making them phase-to-phase with the phase A current. Based on the instantaneous values ​​of the three-phase currents A, B, and C after phase rotation, their average value is taken to obtain the negative sequence current. Based on the rotation operator and the three-phase current values, the positive sequence current component and the negative sequence current component at the protection point are calculated.

[0048] Specifically, the rotation operator 'a' is a fixed mathematical tool for performing symmetric component transformations. In the firmware or algorithm initialization of the protection device, a complex rotation operator is preset, and the mathematical expression of the rotation operator 'a' is: in, To represent the exponential form of complex numbers, i.e., Euler's formula ; j is the imaginary unit, satisfying... ; 120° is the rotation angle, which corresponds to the standard phase difference between each phase in a three-phase AC system.

[0049] Rotate three times to return to the starting point. This means rotating 120° three times consecutively, which is equivalent to rotating one full circle (360°) and returning to the starting direction.

[0050] Obtaining the instantaneous values ​​of three-phase voltage refers to reading the fundamental phasors of the three-phase voltage during the fault period from the data acquisition unit, after filtering and Fourier transform processing, denoted in complex form. This refers to the three-phase currents A, B, and C. Taking the positive-sequence voltage component of phase A as an example, the calculation method is as follows: To rotate the phase B voltage phasor by 120° so that its phase is "aligned" with the phase of the positive sequence component of phase A; To rotate the C-phase voltage phasor by 240° so that its phase is also "aligned" with the phase of the positive sequence component of the A-phase.

[0051] Obtaining the instantaneous values ​​of the three-phase current refers to reading the fundamental phasors of the three-phase current during the fault period from the data acquisition unit after filtering and Fourier transform processing, denoted in complex form. That is, the three-phase currents A, B, and C.

[0052] Taking the positive-sequence current component and negative-sequence current component of phase A as an example, the calculation method is as follows: The complex three-phase coupled current system is decomposed into physically meaningful and independent sequence components. The positive-sequence component reflects the scale of the fault and energy transfer characteristics, while the negative-sequence component is key to identifying system asymmetry (such as two-phase short circuits). The calculated positive and negative-sequence current components are direct inputs for almost all subsequent advanced analyses (such as impedance calculation and adaptive setting). This step ensures that these inputs are mathematically refined information characterizing the essential features of the system, rather than raw, mixed signals containing interphase coupling, thus greatly improving the accuracy and efficiency of subsequent algorithms. The positive-sequence voltage, positive-sequence current, and negative-sequence current calculated in this step are used for fault feature extraction and identification.

[0053] In some implementations, the first adaptive tuning formula is expressed as: in, This is the setting value for the first current protection.

[0054] This is the positive-sequence voltage, calculated using the symmetrical component method at the protection installation point during a fault. It reflects the residual voltage level at the busbar of the protection installation point after the fault. Its value varies in real time with the distance from the fault point, system strength, and distributed power output.

[0055] The system's overall impedance is the equivalent positive-sequence impedance seen from the protection installation point towards the system's power supply side (including the main grid and other power sources operating in parallel). It is a complex number containing both resistive and reactive components. It characterizes the system's "short-circuit capacity" or "strength" at the fault point. The smaller the impedance, the stronger the system, and the larger the short-circuit current.

[0056] The impedance of the line section where the protection installation point is located refers to the total phase distance impedance of the protected line section itself (from the protection installation point to the downstream adjacent node or the end of the line). It is an inherent parameter of the line and determines the voltage drop generated by the fault current on the line.

[0057] The impedance from the protection installation point to the upstream busbar refers to the line (or transformer) impedance between the protection installation point and its directly connected upstream busbar, which determines part of the impedance along the path through which the fault current flows from the system side to the protection point.

[0058] The sum of the output currents provided by all distributed power sources located downstream of the protection installation point refers to the phasor sum (usually considering its amplitude or positive sequence component) of the fault current actually injected into the fault point by all distributed power sources located downstream (load side) of this protection installation point during the fault period, according to their fault ride-through control strategies.

[0059] In some implementations, the second adaptive tuning formula is: in This is the setting value for the second current protection. It is a positive sequence voltage. Protect the impedance of this section of the line where the installation point is located.

[0060] The derivation process of the first and second adaptive tuning formulas is illustrated with examples, and has been applied in actual power distribution networks. , , , How are these parameters calculated?

[0061] Distribution network structure with multiple distributed power sources Figure 3 As shown, For system power, The system impedance is represented by A to E, which represent busbars A to E respectively. S1 to S4 represent circuit breakers 1 to 4 at the protection installation points, and L1 and L2 represent feeders 1 and 2 respectively. DG1, DG2, and DG3 represent multiple distributed power sources connected simultaneously.

[0062] Taking a two-phase short circuit at fault f as an example, the adaptive setting method for the current protection setting at protection installation point S1 is derived as follows: Analyzing the distributed power grid-connected PQ control strategy, the distributed photovoltaic system is equivalent to a current source model controlled by the positive sequence voltage at the grid connection point. Figure 3 Taking the distributed photovoltaic power distribution network structure shown as an example, construct the positive sequence network of the system when a fault occurs at point f. Figure 4 With negative order networks Figure 5 Based on the characteristics of two-phase short-circuit faults in power systems, a composite sequence network is derived. Figure 6 .

[0063] The core derivation idea of ​​this application is to establish an equivalent model of a distribution network with distributed power sources under different fault types based on the symmetrical component method and sequence network analysis. By solving the positive sequence current at the protection installation point, a current protection setting value formula suitable for adaptive setting is derived.

[0064] Figure 4 , 5 In 6, , These are the positive-sequence current and negative-sequence current detected at protection point S1, respectively. For system power; Z S The overall impedance of the S1 back-side system; , These are the positive sequence voltage and negative sequence voltage at the fault point, respectively; , , The output currents of DG1, DG2, and DG3 are respectively; Z AB Z BC Z AE These are the impedances of lines AB, BC, and AE, respectively. a This is the ratio of the distance between the fault point and the protection device.

[0065] The solution process is as follows: ① Utilizing orthogonal order networks Figure 4 Establish the system equations (Formula 1-1), including the system power supply. System impedance Z S Distributed power source injection current ( , ), line impedance (Z) AB Z BC Z AE The fault location coefficient 'a' is a key normalized scaling parameter used to accurately describe the relative position of the fault point on the line. The confirmation method is as follows: (0≤ a ≤1) ② By negative order component network Figure 5 The system's overall impedance Z is obtained. S ; ③ By composite sequence component network Figure 6 Based on the relationship between the composite sequence components of each fault, the positive sequence current at each protection installation point is calculated when a two-phase short-circuit fault occurs on the line, see Formula 1-2; ④ Based on the solved positive sequence current, obtain the adaptive current protection setting value, and refer to formula 1-3.

[0066] Formula (1-1) From Equation 1-1, the expression for the positive sequence current at protection installation point S1 during a two-phase short-circuit fault at f1 can be derived by solving the equation set (Equation 1-2). This expression explicitly includes the contribution of the distributed source current. The voltage drop across the impedance. The positive sequence current of S1 is: Formula (1-2) To meet the reliability and sensitivity requirements of relay protection, the most severe case (a=1) is taken, i.e., the fault occurs at the end of the line, and a reliability coefficient is introduced. When a two-phase short-circuit fault occurs, the adaptive current protection setting formula at protection installation point S1 is: Formula (1-3) In Equation 1-3, To protect the positive sequence voltage measured at the installation point, ZAB represents the line impedance AB. Based on the characteristic that the inverter's maximum allowable short-circuit current is approximately twice its rated current, the output current of the distributed power source during a fault can be calculated. , , The reliability coefficient of the adaptive current protection for two-phase short-circuit faults is 1.2 to 1.3.

[0067] Using this method, the current protection setting formulas at protection installation points S2, S3, and S4 are calculated respectively, as follows: Formula (1-4) Formula (1-5) Formula (1-6) By analyzing the current protection setting formulas for S1, S2, S3, and S4, their mathematical forms are consistent, thus a unified two-phase short-circuit setting formula (Formula 1-7) can be derived: Formula (1-7) In Equations 1-7, To protect the positive sequence voltage measured at the installation point; Z S The overall system impedance can be obtained by dividing the negative sequence voltage at the protection installation point by the negative sequence current; Zup is the impedance from this section of the line to the busbar; Zbase is the impedance of this section of the line. To protect the fault current that the distributed power source downstream of the installation site can provide; The reliability coefficient for adaptive current protection during two-phase short-circuit faults is 1.2 to 1.3. This formula is applicable to the current protection setting value at any protection installation point in the distribution network system.

[0068] The molecule explicitly subtracts the voltage drop term generated by the distributed source current across the system impedance and upstream line impedance, which is a key innovation that distinguishes it from traditional formulas and accurately accounts for the influence of DG.

[0069] Taking a three-phase short circuit with a fault at point f as an example, the adaptive setting method for the current protection setting value at the protection installation point S1 is as follows: When a three-phase short-circuit fault occurs at different locations on the line, due to the symmetry of the three phases, the positive sequence current and positive sequence voltage at the line protection installation point where the fault point is located satisfy the following relationship: Formula (1-8) In Equations 1-8, To protect the positive sequence voltage at the installation location, Let be the impedance between the fault point and the protection installation location. To ensure reliability, the adaptive current protection setting formula at the protection installation location during a three-phase short-circuit fault is as follows: Formula (1-9) The network model is simplified due to the three-phase symmetry. This is achieved through similar reliability handling (accepting end-of-line faults and introducing a reliability coefficient). The general three-phase short-circuit setting formula (Formula 1-9) is obtained as follows: Formula(1-10) In Equation 1-10, To protect the positive sequence voltage measured at the installation point, Z is the impedance of this line. The reliability coefficient for adaptive current protection against three-phase short-circuit faults is 1.2 to 1.3.

[0070] The 10kV distribution network system is a neutral point ungrounded system. Two-phase short-circuit faults differ from three-phase short-circuit faults in their characteristics. Two-phase short-circuit fault currents include both positive-sequence and negative-sequence currents. The three-phase short-circuit fault current only includes the positive sequence current. Therefore, based on the magnitude of the negative sequence current collected at the protection installation point, it can be determined whether it is a two-phase short circuit fault or a three-phase short circuit fault, and then the current protection setting value can be set using formula 1-7 or formula 1-10.

[0071] The first and second adaptive tuning formulas derived above achieve the following core functions: First adaptive tuning formula (1-7, two-phase short-circuit formula): By explicitly introducing and subtracting the DG current voltage drop term ( It accurately offsets the "boost" effect of distributed power sources on the measured voltage of the protection point, so that the calculated setting value truly reflects the short-circuit current level provided by the system side, solves the problem of reduced protection sensitivity (easy failure to operate) caused by DG boost, and can realize differentiated adaptation of fault types.

[0072] The second adaptive tuning formula (1-10, three-phase short-circuit formula): adopts a simplified model, focusing on fast response to the most severe symmetrical faults. The core variables in the formula... These are all real-time measured or online calculated values, which can dynamically reflect the voltage drop at the fault point and the system's equivalent impedance (which changes with DG switching and network topology). Therefore, the setting value... It can automatically follow changes in the system's operating status and always stay near the optimal action threshold.

[0073] Traditional settings rely on a fixed ratio of two-phase and three-phase short-circuit currents. This application, by establishing independent setting models, completely eliminates the dependence on this fixed relationship and fundamentally adapts to the complex and ever-changing reality of fault current ratios after DG access.

[0074] The entire derivation process is ultimately transformed into calculation steps that can be autonomously executed by the protection device (data acquisition → sequence component calculation → fault type identification → formula selection → real-time parameter substitution for calculation). This achieves a fundamental shift from "offline calculation and manual setting" to "online sensing and autonomous setting," improving the real-time performance and accuracy of the protection. The final derived formulas (1-7 and 1-10) are applicable to any protection installation point in the distribution network, requiring only the input of local parameters and measured values ​​for that point, demonstrating good versatility. The formula structure also reserves interfaces for incorporating more complex DG models or new parameter identification methods.

[0075] The derivation process of the setting formula in this application is a process of transforming a complex physical model of a grid fault containing distributed generation (DG) into an embedded, executable mathematical formula with a clear adaptive mechanism. Its core lies in using an innovative formula structure (especially the voltage correction term in the two-phase short-circuit formula) and real-time parameter input to make the current protection setting value an adaptive variable capable of intelligently sensing fault types, dynamically tracking system states, and accurately matching actual short-circuit current levels. This effectively solves the core challenge of current protection setting in distribution networks with high proportions of DG integration.

[0076] In some implementations, step S6 includes: S61: Compare the first current protection setting value or the second current protection setting value with the fault current at the protection point; S62: If the current is less than the fault current, then initiate a delayed trip. If S63 is not less than the fault current, the trip will be initiated immediately.

[0077] This embodiment describes the final logical closed loop of the adaptive protection scheme, which involves "judgment-decision-execution." It achieves precise action control, using an adaptive setting value as a benchmark, combined with delay logic, to realize on-demand, tiered, and reliable fault isolation. "Trip immediately if not less than" ensures speed, "delay if less than" ensures selectivity and reliability, and the adaptive value as the criterion ensures sensitivity. This transforms the value of the adaptive algorithm into actual safety benefits. Ultimately, the results of all adaptive calculations (precise...) All of these are transformed into actual control actions to protect the safe and reliable operation of the power grid through this simple yet rigorous comparative logic, thus completing the value loop from "intelligent analysis" to "safety protection".

[0078] In some implementations, step S62 includes: If the setting value of the first current protection or the setting value of the second current protection is greater than the fault current at the protection point; Reacquire the relevant data to calculate the first current protection setting value or the second current protection setting value; If the recalculated first current protection setting value or second current protection setting value is not less than the fault current within the predetermined time, the tripping will be initiated immediately. If the predetermined time is reached, the trip will be initiated immediately, regardless of whether the first current protection setting value or the second current protection setting value is less than the fault current.

[0079] This implementation method is an intelligent enhancement of the basic time-delay trip logic. Its core function lies in realizing dynamic self-verification and intelligent decision optimization of protection. Traditional time-delay protection "passively waits" during the delay period. This method actively recalculates the setting value during the delay period, which is a kind of dynamic self-verification. If the fault is transient or is being cleared by other protections, the system state will recover quickly, and the recalculated setting value may be significantly increased (due to voltage recovery and impedance changes), thus causing the condition of "not less than the fault current" to no longer be met. This makes it possible to terminate unnecessary tripping in advance during the delay period, further preventing false tripping. The delay time window is transformed from a "waiting" period into an intelligent decision-making period of continuous perception and evaluation. The protection device no longer relies solely on the initial "snapshot" to make decisions, but dynamically adjusts its decisions based on the latest system state.

[0080] Please see Figure 7 As shown, in one embodiment, a current protection setting adaptive setting device is provided, the device comprising: The fault identification module is used to acquire and determine in real time whether the three-phase current at the protection point is abnormal. If so, obtain the three-phase current value at the protection point, and calculate the positive sequence current and negative sequence current at the protection point based on the three-phase current; The fault type determination module is used to determine the fault type based on the characteristics of the positive sequence current and negative sequence current at the protection point. If it is determined to be a two-phase short circuit, obtain the reliability coefficient of the two-phase short circuit current protection, the output current value of the distributed power source, the two-phase short circuit current protection coefficient, the positive sequence voltage at the protection point, the system comprehensive impedance, the fault line impedance, and the impedance from the fault point to the bus, and calculate the two-phase short circuit adaptive setting value. If it is determined to be a three-phase short circuit, obtain the three-phase short circuit current protection coefficient, the positive sequence voltage at the protection point and the fault line impedance, and calculate the three-phase short circuit adaptive setting value. The protection action issuing module is used to issue protection actions based on the two-phase short-circuit adaptive setting value or the three-phase short-circuit adaptive setting value.

[0081] In one embodiment, a computer device is provided, which may be a server, and its internal structure diagram may be as follows: Figure 8 As shown. The computer device includes a processor, memory, network interface, and database connected via a system bus. The processor provides computing and control capabilities. The memory includes non-volatile and / or volatile storage media and internal memory. The non-volatile storage media stores the operating system, computer programs, and database. The internal memory provides an environment for the operation of the operating system and computer programs in the non-volatile storage media. The network interface is used to communicate with external clients via a network connection. When the computer program is executed by the processor, it implements the functions or steps of a current protection setting adaptive setting method on the server side. The current protection setting adaptive setting method includes: When a line fault is detected, the instantaneous values ​​of the three-phase voltage and the three-phase current at the protection point are obtained; Calculate the positive sequence voltage, positive sequence current, and negative sequence current at the protection point based on the instantaneous values ​​of the three-phase voltage and the three-phase current. Determine the fault type based on the negative sequence current; If the fault type is a two-phase short-circuit fault, the first current protection setting value is calculated according to the first adaptive setting formula. The input of the first adaptive setting formula includes at least: positive sequence voltage, system comprehensive impedance, impedance of the line where the protection installation point is located, impedance from the protection installation point to the upstream bus, and the sum of the output currents provided by all distributed power sources located downstream of the protection installation point. If the fault type is a three-phase short-circuit fault, the second current protection setting value is calculated according to the second adaptive setting formula; the input of the second adaptive setting formula includes at least: positive sequence voltage and the impedance of the line segment where the protection installation point is located; Based on the first current protection setting value or the second current protection setting value, the corresponding overcurrent protection action is performed on the distribution network.

[0082] The technical solution disclosed in this application can accurately determine the fault type by acquiring the instantaneous values ​​of three-phase voltage and current at the protection point of the faulty line in real time and calculating key sequence components such as positive-sequence voltage, positive-sequence current, and negative-sequence current. In particular, it effectively distinguishes between two-phase short circuits and three-phase short circuits based on the characteristics of negative-sequence current, solving the problem of difficult fault identification caused by the failure of traditional fault current ratio relationships in distributed power supply scenarios. This application designs differentiated adaptive setting strategies for different fault types: for two-phase short circuit faults, the first adaptive setting formula comprehensively incorporates multiple real-time parameters such as positive-sequence voltage, system comprehensive impedance, line impedance, and the contribution of downstream distributed power supply fault current to dynamically generate protection setting values ​​that match the characteristics of this type of asymmetrical fault; for three-phase short circuit faults, the second adaptive setting formula adaptively generates setting values ​​suitable for symmetrical faults based on key parameters such as positive-sequence voltage and line impedance. Ultimately, protection actions are executed based on the adaptively generated setting values, thereby enabling dynamic adjustment of current protection setting values ​​for different fault types in complex distribution network environments with widespread distributed power source integration, according to system status and fault characteristics. This significantly improves the adaptability, selectivity, and reliability of the protection, effectively avoiding the maloperation or failure to operate problems that easily occur in traditional fixed-setting protection methods under the influence of system impedance changes and distributed power sources. This application utilizes the characteristic differences between positive-sequence and negative-sequence currents to accurately distinguish between two-phase short circuits and three-phase short circuits, providing a key judgment basis for differentiated setting and solving the problem of difficulty in accurately identifying fault types due to the failure of the fault current ratio relationship caused by the integration of distributed power sources.

[0083] In one embodiment, a computer-readable storage medium is provided that stores a computer program, which, when executed by a processor, performs the following steps: When a line fault is detected, the instantaneous values ​​of the three-phase voltage and the three-phase current at the protection point are obtained; Calculate the positive sequence voltage, positive sequence current, and negative sequence current at the protection point based on the instantaneous values ​​of the three-phase voltage and the three-phase current. Determine the fault type based on the negative sequence current; If the fault type is a two-phase short-circuit fault, the first current protection setting value is calculated according to the first adaptive setting formula. The input of the first adaptive setting formula includes at least: positive sequence voltage, system comprehensive impedance, impedance of the line where the protection installation point is located, impedance from the protection installation point to the upstream bus, and the sum of the output currents provided by all distributed power sources located downstream of the protection installation point. If the fault type is a three-phase short-circuit fault, the second current protection setting value is calculated according to the second adaptive setting formula; the input of the second adaptive setting formula includes at least: positive sequence voltage and the impedance of the line segment where the protection installation point is located; Based on the first current protection setting value or the second current protection setting value, the corresponding overcurrent protection action is performed on the distribution network.

[0084] The technical solution disclosed in this application can accurately determine the fault type by acquiring the instantaneous values ​​of three-phase voltage and current at the protection point of the faulty line in real time and calculating key sequence components such as positive-sequence voltage, positive-sequence current, and negative-sequence current. In particular, it effectively distinguishes between two-phase short circuits and three-phase short circuits based on the characteristics of negative-sequence current, solving the problem of difficult fault identification caused by the failure of traditional fault current ratio relationships in distributed power supply scenarios. This application designs differentiated adaptive setting strategies for different fault types: for two-phase short circuit faults, the first adaptive setting formula comprehensively incorporates multiple real-time parameters such as positive-sequence voltage, system comprehensive impedance, line impedance, and the contribution of downstream distributed power supply fault current to dynamically generate protection setting values ​​that match the characteristics of this type of asymmetrical fault; for three-phase short circuit faults, the second adaptive setting formula adaptively generates setting values ​​suitable for symmetrical faults based on key parameters such as positive-sequence voltage and line impedance. Ultimately, protection actions are executed based on the adaptively generated setting values, thereby enabling dynamic adjustment of current protection setting values ​​for different fault types in complex distribution network environments with widespread distributed power source integration, according to system status and fault characteristics. This significantly improves the adaptability, selectivity, and reliability of the protection, effectively avoiding the maloperation or failure to operate problems that easily occur in traditional fixed-setting protection methods under the influence of system impedance changes and distributed power sources. This application utilizes the characteristic differences between positive-sequence and negative-sequence currents to accurately distinguish between two-phase short circuits and three-phase short circuits, providing a key judgment basis for differentiated setting and solving the problem of difficulty in accurately identifying fault types due to the failure of the fault current ratio relationship caused by the integration of distributed power sources.

[0085] It should be noted that the functions or steps that can be implemented by the computer-readable storage medium or computer device described above can be referred to the relevant descriptions on the server side and client side in the foregoing method embodiments. To avoid repetition, they will not be described one by one here.

[0086] Those skilled in the art will understand that all or part of the processes in the methods of the above embodiments can be implemented by a computer program instructing related hardware. The computer program can be stored in a non-volatile computer-readable storage medium. When executed, the computer program can include the processes of the embodiments of the above methods. Any references to memory, storage, databases, or other media used in the embodiments provided in this application can include non-volatile and / or volatile memory. Non-volatile memory may include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memory may include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), dual data rate SDRAM (DDRSDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), RAMbus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0087] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the above-described division of functional units and modules is used as an example. In practical applications, the above functions can be assigned to different functional units and modules as needed, that is, the internal structure of the device can be divided into different functional units or modules to complete all or part of the functions described above.

[0088] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be included within the protection scope of the present invention.

Claims

1. A current protection setting value adaptive setting method, characterized in that, The method includes: When a line fault is detected, the instantaneous values ​​of the three-phase voltage and the three-phase current at the protection point are obtained; Based on the instantaneous values ​​of the three-phase voltage and the instantaneous values ​​of the three-phase current, calculate the positive sequence voltage, positive sequence current, and negative sequence current at the protection point; The fault type is determined based on the negative sequence current. If the fault type is a two-phase short-circuit fault, the first current protection setting value is calculated according to the first adaptive setting formula; the input of the first adaptive setting formula includes at least: the positive sequence voltage, the system comprehensive impedance, the impedance of the line where the protection installation point is located, the impedance from the protection installation point to the upstream bus, and the sum of the output currents provided by all distributed power sources located downstream of the protection installation point; If the fault type is a three-phase short-circuit fault, the second current protection setting value is calculated according to the second adaptive setting formula; the input of the second adaptive setting formula includes at least: the positive sequence voltage and the impedance of the line segment where the protection installation point is located; Based on the first current protection setting value or the second current protection setting value, the corresponding overcurrent protection action is performed on the distribution network.

2. The adaptive setting method for current protection setting value according to claim 1, characterized in that, The overall system impedance is obtained by dividing the positive sequence voltage measured at the protection point by the positive sequence current at the fault location.

3. The adaptive setting method for current protection setting value according to claim 1, characterized in that, The step of calculating the positive-sequence voltage, positive-sequence current, and negative-sequence current at the protection point based on the instantaneous values ​​of the three-phase voltage and the instantaneous values ​​of the three-phase current includes: Obtain the rotating operator, as well as the instantaneous values ​​of the three-phase currents and voltages of phases A, B, and C; The phase B voltage and phase C voltage are rotated by 120° and 240° respectively by the rotation operator so that they are in phase with phase A voltage. The positive sequence voltage is obtained by averaging the instantaneous values ​​of the three phase voltages A, B and C after the phase rotation. The phase B current and the phase C current are rotated by 120° and 240° respectively by the rotation operator so that they are in the same phase as the phase A current. The positive sequence current is obtained by taking the average value of the instantaneous values ​​of the three phase currents A, B and C after the phase rotation. The phase B current and the phase C current are rotated by 240° and 120° respectively by the rotation operator so that they are in the same phase as the phase A current. The negative sequence current is obtained by taking the average value of the instantaneous values ​​of the three phase currents A, B and C after the phase rotation.

4. The adaptive setting method for current protection setting value according to claim 1, characterized in that, The first adaptive tuning formula expression is: is a first current protection setting value; is a positive sequence voltage; is a system aggregate impedance; is a section impedance of a line on which the protection installation point is located; is an impedance from the protection installation point to an upstream bus; is a sum of output currents provided by all distributed power sources located downstream of the protection installation point.

5. The adaptive setting method for current protection setting value according to claim 1, characterized in that, The second adaptive tuning formula is: in This is the setting value for the second current protection. It is a positive sequence voltage. Protect the impedance of this section of the line where the installation point is located.

6. The adaptive setting method for current protection setting value according to claim 1, characterized in that, The step of performing corresponding overcurrent protection actions on the distribution network according to the first current protection setting value or the second current protection setting value includes: Compare the first current protection setting value or the second current protection setting value with the fault current at the protection point; If the current is less than the fault current, a delayed trip will be initiated. If the fault current is not less than the stated fault current, the tripping function will be initiated immediately.

7. The adaptive setting method for current protection setting value according to claim 6, characterized in that, The step of initiating a delayed trip if the fault current is greater than the fault current includes: If the first current protection setting value or the second current protection setting value is less than the fault current at the protection point; Reacquire the relevant data to calculate the first current protection setting value or the second current protection setting value; If, within the predetermined time, the recalculated first current protection setting value or the second current protection setting value is not less than the fault current, then the tripping will be initiated immediately. If the predetermined time is reached, regardless of whether the first current protection setting value or the second current protection setting value is less than the fault current, the tripping will be initiated immediately.

8. A current protection setting adaptive setting device, characterized in that, The device includes: The fault identification module is used to acquire and determine in real time whether the three-phase current at the protection point is abnormal. If so, obtain the three-phase current value at the protection point, and calculate the positive sequence current and negative sequence current at the protection point based on the three-phase current; The fault type determination module is used to determine the fault type based on the characteristics of the positive sequence current and negative sequence current at the protection point. If it is determined to be a two-phase short circuit, obtain the reliability coefficient of the two-phase short circuit current protection, the output current value of the distributed power source, the two-phase short circuit current protection coefficient, the positive sequence voltage at the protection point, the system comprehensive impedance, the fault line impedance, and the impedance from the fault point to the bus, and calculate the two-phase short circuit adaptive setting value. If it is determined to be a three-phase short circuit, obtain the three-phase short circuit current protection coefficient, the positive sequence voltage at the protection point and the fault line impedance, and calculate the three-phase short circuit adaptive setting value. The protection action issuing module is used to make protection actions based on the two-phase short-circuit adaptive setting value or the three-phase short-circuit adaptive setting value.

9. A computer device, characterized in that, The computer device includes a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein the processor, when executing the computer program, implements the steps of the current protection setting adaptive setting method as described in any one of claims 1 to 7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, implements the steps of adaptive setting of the current protection setting value as described in any one of claims 1 to 7.

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