Ground fault detection method of master station linkage and related device

Abstract

The invention provides a main station linkage ground fault detection method and a related device, and relates to the technical field of power grids. According to the main station linkage ground fault detection method, a bus tie switch linkage fault feature amplification mechanism is adopted, and when the maximum first zero-sequence current is smaller than a first preset current threshold value in first zero-sequence currents of feeder lines connected with a first bus, the maximum first zero-sequence current is smaller than the first preset current threshold value; a target bus tie switch used for connecting a first bus and a second bus which is adjacent to the first bus and is in a non-fault state is controlled to be switched on, so that capacitance current of the second bus flows into a feeder line which is connected with the first bus and is in a ground fault state through the target bus tie switch; the first zero-sequence current of the feeder line in the ground fault state is increased, the selection accuracy of the feeder line with the ground fault is improved, and then the detection accuracy of the ground fault is improved.

Description

Technical Field

[0001] This application relates to the field of power grid technology, and in particular to a ground fault detection method and related device for master station linkage. Background Technology

[0002] As a crucial component of urban power grids, the stable operation of 10kV distribution networks directly impacts the safety of power supply for industrial production, residential life, and public facilities. In distribution networks with a neutral point grounded by a small resistance, single-phase grounding faults are the most common type of fault on 10kV lines. If a single-phase grounding fault occurs and the faulty line is not isolated in time, it can lead to phase-to-phase short circuits, equipment insulation damage, personal safety risks, and large-scale power outages. Therefore, timely and accurate detection and location of single-phase grounding faults are essential for the safe operation of distribution networks.

[0003] In related technologies, the zero-sequence protection fault location method is commonly used to detect single-phase grounding faults in 10kV distribution networks. Specifically, the zero-sequence current is collected by the zero-sequence current protection device corresponding to each feeder line on the busbar, and all collected zero-sequence currents are uploaded to the master station. Based on the maximum zero-sequence current criterion, the master station determines the feeder line corresponding to the largest zero-sequence current among all zero-sequence currents as the grounding fault line.

[0004] However, the inventors discovered that the above-mentioned zero-sequence protection line selection method has the problem of low accuracy in grounding fault detection in some scenarios. Summary of the Invention

[0005] This application provides a ground fault detection method and related device with master station linkage, which solves the problem that the ground fault detection accuracy is low in some scenarios when using the zero-sequence protection line selection method to detect ground faults in 10kV distribution networks.

[0006] In a first aspect, this application provides a ground fault detection method for master station linkage, comprising: acquiring the first zero-sequence current of each feeder line connected to the first busbar; determining whether the maximum first zero-sequence current in each feeder line is greater than or equal to a first preset current threshold; if the maximum first zero-sequence current is less than the first preset current threshold, controlling the target bus tie switch to close, and acquiring the second zero-sequence current of each feeder line, wherein the target bus tie switch is used to connect the first busbar and the second busbar, the second busbar being a busbar adjacent to the first busbar in a non-fault state; and detecting the ground fault line based on the first zero-sequence current and the second zero-sequence current of each feeder line.

[0007] In one possible implementation, the ground fault line is detected based on the first zero-sequence current and the second zero-sequence current of each feeder line, including: determining whether the first zero-sequence current and the second zero-sequence current of each feeder line meet preset conditions; if the first zero-sequence current and the second zero-sequence current of any feeder line meet the preset conditions, then the feeder line is determined to be a ground fault line.

[0008] In one possible implementation, the ground fault detection method further includes: if the first zero-sequence current and the second zero-sequence current of any feeder line do not meet the preset conditions, then the feeder line is determined to be a non-ground fault line.

[0009] In one possible implementation, the ground fault detection method further includes: if the maximum first zero-sequence current is greater than or equal to a first preset current threshold, then the feeder line corresponding to the maximum first zero-sequence current is determined to be a ground fault line.

[0010] In one possible implementation, the ground fault detection method further includes: dynamically adjusting the closing time of the target bus tie switch based on the load status of the distribution network system to which the first bus belongs and the changing trend of the fault characteristics of the first bus.

[0011] In one possible implementation, obtaining the first zero-sequence current of each feeder line connected to the first busbar includes: when the busbar zero-sequence voltage of the first busbar is detected to be greater than a preset voltage threshold, and the first zero-sequence current of each feeder line is less than a second preset current threshold, obtaining the first zero-sequence current of each feeder line, wherein the second preset current threshold is greater than the first preset current threshold.

[0012] Secondly, this application provides a grounding fault detection device for master station linkage, comprising:

[0013] The acquisition module is used to acquire the first zero-sequence current of each feeder line connected to the first busbar.

[0014] The determination module is used to determine whether the maximum first zero-sequence current in the first zero-sequence current of each feeder line is greater than or equal to a first preset current threshold.

[0015] The processing module is used to control the target bus tie switch to close when the maximum first zero-sequence current is less than the first preset current threshold, and to obtain the second zero-sequence current of each feeder line. The target bus tie switch is used to connect the first bus and the second bus, and the second bus is the bus adjacent to the first bus and in a non-faulty state.

[0016] The detection module is used to detect ground fault lines based on the first zero-sequence current and the second zero-sequence current of each feeder line.

[0017] In one possible implementation, the detection module is specifically used to: determine whether the first zero-sequence current and the second zero-sequence current of each feeder line meet preset conditions; if the first zero-sequence current and the second zero-sequence current of any feeder line meet the preset conditions, then the feeder line is determined to be a ground fault line.

[0018] In one possible implementation, the detection module is also used to determine that a feeder line is a non-grounded fault line when the first zero-sequence current and the second zero-sequence current of any feeder line do not meet the preset conditions.

[0019] In one possible implementation, the determining module is further configured to: determine the feeder line corresponding to the maximum first zero-sequence current as a ground fault line when the maximum first zero-sequence current is greater than or equal to a first preset current threshold.

[0020] In one possible implementation, the ground fault detection device linked to the master station also includes a dynamic adjustment module (not shown), which is used to dynamically adjust the closing time of the target bus tie switch according to the load status of the distribution network system to which the first bus belongs and the changing trend of the fault characteristics of the first bus.

[0021] In one possible implementation, the acquisition module is specifically used to: when the bus zero-sequence voltage of the first bus is detected to be greater than a preset voltage threshold, and the first zero-sequence current of each feeder line is less than a second preset current threshold, acquire the first zero-sequence current of each feeder line, wherein the second preset current threshold is greater than the first preset current threshold.

[0022] Thirdly, this application provides an electronic device, including: a processor and a memory communicatively connected to the processor; the memory stores computer-executable instructions; the processor executes the computer-executable instructions stored in the memory to implement the ground fault detection method for master station linkage as provided in the first aspect above.

[0023] Fourthly, this application provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, are used to implement the ground fault detection method for master station linkage as provided in the first aspect above.

[0024] Fifthly, this application provides a computer program product, comprising: a computer program that, when executed by a processor, implements the ground fault detection method for master station linkage as provided in the first aspect above.

[0025] The ground fault detection method and related apparatus for master station linkage provided in this application involve acquiring the first zero-sequence current of each feeder line connected to the first busbar, determining whether the maximum first zero-sequence current among the first zero-sequence currents of each feeder line is greater than or equal to a first preset current threshold, further controlling the target bus tie switch to close when the maximum first zero-sequence current is less than the first preset current threshold, and acquiring the second zero-sequence current of each feeder line. Then, based on the first and second zero-sequence currents of each feeder line, the ground fault line is detected. The target bus tie switch is used to connect the first busbar and the second busbar, where the second busbar is the busbar adjacent to the first busbar and is in a non-faulty state. This application employs a fault characteristic amplification mechanism linked by a bus tie switch. When the maximum first zero-sequence current in the first zero-sequence current of each feeder line connected to the first bus is less than a first preset current threshold, the target bus tie switch used to connect the first bus and the second bus adjacent to the first bus in a non-faulty state is closed. This causes the capacitive current of the second bus to flow through the target bus tie switch into the feeder line connected to the first bus that is in a ground fault state, increasing the first zero-sequence current of the feeder line in a ground fault state, improving the accuracy of selecting the feeder line in a ground fault state, and thus improving the accuracy of ground fault detection. Attached Figure Description

[0026] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0027] Figure 1 This is a structural diagram illustrating an application scenario provided in an embodiment of this application.

[0028] Figure 2 A flowchart illustrating the grounding fault detection method for master station linkage provided in this application embodiment. Figure 1 ;

[0029] Figure 3 A flowchart illustrating the grounding fault detection method for master station linkage provided in this application embodiment. Figure 2 ;

[0030] Figure 4 A schematic diagram of the grounding fault detection device for master station linkage provided in an embodiment of this application;

[0031] Figure 5 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.

[0032] The accompanying drawings illustrate specific embodiments of this application, which will be described in more detail below. These drawings and descriptions are not intended to limit the scope of the concept in any way, but rather to illustrate the concept of this application to those skilled in the art through reference to particular embodiments. Detailed Implementation

[0033] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0034] Single-phase grounding faults are the most common type of fault on 10kV lines (accounting for over 80%). In distribution network systems with a neutral point grounded through a small resistor, if the substation is not equipped with a ground fault location device, when a single-phase grounding fault occurs on a 10kV line, the zero-sequence protection device on the 10kV line side typically operates to disconnect the circuit breaker of the grounded line and isolate the fault. However, when the transition resistance of a single-phase grounding fault is relatively high (i.e., a high-resistance grounding occurs), the zero-sequence current of the grounded line is too small and may not reach the operating current threshold of the zero-sequence protection. This results in the zero-sequence protection failing to operate reliably after a single-phase grounding fault occurs, thus failing to isolate the grounded line in a timely manner.

[0035] In related technologies, the zero-sequence protection line selection method is commonly used to detect single-phase grounding faults in 10kV distribution networks. Specifically, when configuring a master station (i.e., a relay protection master station) in a substation, the master station collects the zero-sequence current of each 10kV line in the entire substation, and selects the line with the largest zero-sequence current as the grounding fault line. However, in high-resistance grounding scenarios, the zero-sequence current of the grounding fault line is very small and close to that of the non-faulty line. That is, the distinction between the zero-sequence current of the grounding fault line and the non-faulty line is not high, and the zero-sequence current of the non-faulty line may even be greater than that of the grounding fault line. In this scenario, considering the error, it may lead to the incorrect selection of the grounding fault line, resulting in a low accuracy rate in grounding fault line selection and consequently, low accuracy in grounding fault detection.

[0036] Currently, most distribution network systems adopt a dual-busbar segmented operation architecture, comprising two independent busbars (e.g., Busbar 1 and Busbar 2), each connected to multiple 10kV feeder lines. The bus tie switch (i.e., the segment switch) connecting the two independent busbars is normally open, ensuring complete isolation between the two independent busbars and their respective connected 10kV feeder lines. In this distribution network system, when a ground fault occurs on any 10kV feeder line connected to a busbar segment, a zero-sequence protection line selection method is used to select the faulty line from among the multiple 10kV feeder lines connected to that busbar segment. The capacitive current of the other busbar segment, which is not faulty, remains idle. However, in high-resistance ground fault scenarios, the zero-sequence protection line selection method used in this architecture still suffers from low accuracy in selecting the ground faulty line, leading to low accuracy in ground fault detection.

[0037] Based on the problems existing in related technologies, this application embodiment adopts a fault feature amplification mechanism through bus tie switch linkage. When the maximum zero-sequence current in the zero-sequence current of each feeder line connected to the bus in a fault state is less than a preset current threshold, the bus tie switch used to connect the bus in a fault state and the bus in a non-fault state is closed. This allows the capacitive current of the bus in a non-fault state to flow through the bus tie switch into the feeder line connected to the bus in a fault state that is in a ground fault state. This increases the zero-sequence current of the feeder line in a ground fault state, improves the accuracy of selecting the feeder line in a ground fault state, and thus improves the accuracy of ground fault detection.

[0038] The following is a combination of... Figure 1 The application scenarios of the embodiments of this application will be described.

[0039] Figure 1 This is a structural diagram illustrating an application scenario provided in an embodiment of this application. For example... Figure 1 As shown, the power distribution network system in this application scenario includes two busbars, such as busbar 1 and busbar 2. Busbar 1 and busbar 2 are connected by a bus tie switch.

[0040] For example, the distribution network system can be a 10kV distribution network system with a neutral point grounded through a small resistor, which adopts a multi-bus segmented operation architecture. Under this architecture, multiple bus segments operate in isolation through bus switch, and each bus segment connects to multiple 10kV feeder lines.

[0041] like Figure 1As shown, busbar 1 and busbar 2 are each connected to three 10kV feeder lines. For example, busbar 1 is connected to feeder line 1, feeder line 2, and feeder line 3, while busbar 2 is connected to feeder line 4, feeder line 5, and feeder line 6. Each 10kV feeder line is connected to a zero-sequence current protection device 11, and the output terminal of each 10kV feeder line is grounded through the distribution network system.

[0042] like Figure 1 As shown, when a single-phase ground fault occurs at any point K on feeder line 1 connected to bus 1, the fault point will form a fault equivalent power source 14 and a grounding resistance 15 (i.e., transition resistance). At this time, feeder line 1 will generate a zero-sequence current. Under normal operating conditions of the distribution network system, the bus tie switch connecting bus 1 and bus 2 is in the open state, and the 10kV feeder lines connected to bus 2 are not connected to the fault circuit. Therefore, no zero-sequence current is generated.

[0043] like Figure 1 As shown, one end of the fault equivalent power supply 14 is grounded, and the other end of the fault equivalent power supply 14 is connected to one end of the grounding resistor 15. The other end of the grounding resistor 15 is connected to the fault point K on feeder line 1. For the ground fault loop of bus 1, the fault equivalent power supply 14, the grounding resistor 15, and feeder line 1 are connected in series, and then connected in parallel with feeder line 2, feeder line 3, and the small neutral point grounding resistor corresponding to bus 1 to form a closed loop. At this time, the zero-sequence current I01 of feeder line 1 is the reverse value of the sum of the zero-sequence current I02 of feeder line 2, the zero-sequence current I03 of feeder line 3, and the zero-sequence current I0R1 of the small neutral point grounding resistor corresponding to bus 1, as shown. Figure 1 As shown in solid line frame 12.

[0044] For example, the zero-sequence current I01 of feeder line 1 can be expressed by the following formula:

[0045]

[0046] If, after a fault in busbar 1, the bus tie switch is closed, causing busbars 1 and 2 to operate as a single busbar section, then the zero-sequence current I01 of feeder line 1 is the reverse value of the sum of the zero-sequence currents I02, I03, I0R1 of the neutral grounding resistor corresponding to busbar 1, I04, I05, I06, and I0R2 of the neutral grounding resistor corresponding to busbar 2. Figure 1 As shown in solid box 12 and dashed box 13.

[0047] For example, the zero-sequence current I01 of feeder line 1 can be expressed by the following formula:

[0048]

[0049] Based on the above, it can be seen that after a single-phase ground fault occurs on bus 1, by comparing the zero-sequence current distribution before and after the bus tie switch is closed, the zero-sequence current flowing through the ground fault line, i.e., feeder line 1 on bus 1, will increase significantly after the bus tie switch is closed, which can effectively improve the sensitivity of ground fault detection.

[0050] It should be noted that, Figure 1 The power distribution network system shown is only an example. The ground fault detection method with master station linkage provided in this application does not limit the number of segmented busbars in the power distribution network system or the number of feeders connected to each segmented busbar.

[0051] It is understood that the ground fault detection method for master station linkage provided in this application embodiment is applied to the master station, the distribution network corresponding to the master station includes multiple bus sections, and adjacent two bus sections are connected by a bus tie switch.

[0052] The specific implementation of the grounding fault detection method for master station linkage provided in this application embodiment will be described in detail below with reference to specific embodiments.

[0053] Figure 2 A flowchart illustrating the grounding fault detection method for master station linkage provided in this application embodiment. Figure 1 .like Figure 2 As shown, a specific implementation of the ground fault detection method linked to the master station may include the following steps:

[0054] S201, obtain the first zero-sequence current of each feeder line connected to the first bus.

[0055] For example, the first busbar can be as described above. Figure 1 The diagram shows a busbar in the distribution network system that experiences a single-phase ground fault. Under normal operating conditions, the bus tie switch between this first busbar and other adjacent busbars is open, meaning the first busbar operates independently.

[0056] The number of feeder lines connected to the first busbar in this embodiment is not limited; it can be determined according to the actual application requirements.

[0057] In this step, one possible implementation is as follows: When a single-phase ground fault is detected in the distribution network to which the first busbar belongs, the zero-sequence current transformers configured on each feeder line connected to the first busbar collect the first zero-sequence current of the corresponding feeder line in real time, and upload the collected first zero-sequence current of each feeder line connected to the first busbar to the master station via a distribution terminal such as a feeder terminal unit (FTU) or a remote terminal unit (RTU). The master station fault detection device (as described above) in the master station... Figure 1 The system (as shown in the diagram) receives this data and performs single-phase grounding fault detection based on the first zero-sequence current of each feeder line connected to the first busbar. The main station fault detection device establishes a communication connection with all 10kV feeder lines within the distribution network to which the first busbar belongs via a distribution terminal.

[0058] For example, the zero-sequence current transformers configured on each feeder line can be integrated into the above-mentioned Figure 1 The zero-sequence current protection devices on each feeder line shown.

[0059] S202, determine whether the maximum first zero-sequence current in the first zero-sequence current of each feeder line is greater than or equal to the first preset current threshold.

[0060] For example, the first preset current threshold can be determined comprehensively based on factors such as the background capacitance current of the distribution network to which the first bus belongs, the minimum grounding current of a high-resistance grounding fault, and measurement errors (such as the measurement error of the zero-sequence current transformer, the measurement error of the feeder terminal unit, etc.). This application embodiment does not limit the magnitude of the first preset current threshold; it can be determined specifically according to actual application requirements.

[0061] It is understandable that when a high-resistance ground fault occurs in a 10kV feeder line connected to the first busbar, although the zero-sequence current of the corresponding ground fault line is very small, its amplitude is still the reverse value of the sum of the zero-sequence currents of the other 10kV feeder lines connected to the first busbar and the small resistance of the neutral point grounding of the first busbar, as shown in the above formula (1). Based on this, the largest first zero-sequence current can be selected from the first zero-sequence currents of each feeder line.

[0062] For example, the first busbar is as described above. Figure 1 When busbar 1 is shown, that is, the first busbar is connected to three 10kV feeder lines, namely feeder line 1, feeder line 2, and feeder line 3. In this case, the method for selecting the largest first zero-sequence current from the first zero-sequence currents of each feeder line can be expressed by the following formula:

[0063]

[0064] in, Indicates the maximum first zero-sequence current. These represent the first zero-sequence currents corresponding to feeder lines 1, 2, and 3 connected to the first busbar, respectively.

[0065] It is understandable that after selecting the maximum first zero-sequence current, to eliminate the problem of poor differentiation between feeder lines due to excessively small zero-sequence current and measurement errors (such as measurement errors of zero-sequence current transformers), which could lead to incorrect selection of the ground fault line, the ground fault detection method with master station linkage provided in this application further determines the maximum first zero-sequence current based on a first preset current threshold, thereby reducing the probability of incorrect selection of the ground fault line and improving the line selection accuracy.

[0066] In this step, one possible implementation is as follows: select the maximum first zero-sequence current from the first zero-sequence current of each feeder line, and determine whether the maximum first zero-sequence current is greater than or equal to the first preset current threshold. If the maximum first zero-sequence current is greater than or equal to the first preset current threshold, then determine that the feeder line corresponding to the maximum first zero-sequence current is a ground fault line; if the maximum first zero-sequence current is less than the first preset current threshold, then execute step S203.

[0067] For example, the determination of the maximum first zero-sequence current can be expressed by the following formula:

[0068]

[0069] in, This indicates the preset threshold for the first current.

[0070] It is understandable that when the maximum first zero-sequence current is greater than or equal to the first preset current threshold, it indicates that the selected ground fault line is valid, so the feeder line corresponding to the maximum first zero-sequence current can be identified as the ground fault line.

[0071] For example, if there are multiple maximum first zero-sequence currents in each feeder line that satisfy the condition of being greater than or equal to a first preset current threshold (i.e., the amplitude of the first zero-sequence currents in multiple feeder lines is the same and they are all maximum values, and the maximum value is greater than or equal to the first preset current threshold), then the feeder lines corresponding to the multiple maximum first zero-sequence currents are all identified as ground fault lines.

[0072] S203 controls the closing of the target bus tie switch and obtains the second zero-sequence current of each feeder line.

[0073] The target bus tie switch is used to connect the first busbar and the second busbar, where the second busbar is an adjacent busbar in a non-faulty state. For example, in a distribution network containing only two busbars, namely the first busbar and the second busbar, the target bus tie switch is the bus tie switch connecting the first busbar and the second busbar, as described above. Figure 1 The diagram shows busbar 1, busbar 2, and the bus tie switch connecting busbar 1 and busbar 2.

[0074] For example, when a distribution network contains multiple busbars, and there are non-faulty busbars connected to both sides of the first busbar by different bus tie switches, the master station performs topology priority analysis based on the topology information of the distribution network to which the first busbar belongs (such as feeder line connection relationships, busbar load capacity, etc.), and determines the bus tie switch that contributes the most to the increase in the zero-sequence current amplitude of the ground fault line as the target bus tie switch. For example, when the busbars adjacent to the first busbar include busbar 3 and busbar 4, if the ground capacitance current capacity of busbar 3 is greater than that of busbar 4, then the bus tie switch connecting the first busbar and busbar 3 is determined as the target bus tie switch. By controlling the closing of this target bus tie switch, the first zero-sequence current characteristic (i.e., the first zero-sequence current amplitude) of the ground fault line can be maximized, thereby improving the ground fault detection sensitivity.

[0075] Based on the above Figure 1 As shown, it can be understood that after the target bus tie switch is closed, the zero-sequence current of each feeder line connected to the second bus will flow into the feeder line connected to the first bus that has experienced a single-phase ground fault. That is, among the feeder lines connected to the first bus, the second zero-sequence current amplitude corresponding to the feeder line that only has a single-phase ground fault will be significantly greater than the first zero-sequence current amplitude before the target bus tie switch is closed. For the feeder lines that do not have a single-phase ground fault, the corresponding second zero-sequence current amplitude is basically the same as the first zero-sequence current amplitude before the target bus tie switch is closed (e.g., the difference between the second zero-sequence current amplitude and the first zero-sequence current amplitude is within the allowable range of measurement error).

[0076] For example, the first busbar and the second busbar are respectively described above. Figure 1 When busbar 1 and busbar 2 are shown, after the control target bus tie switch is closed, the second zero-sequence current of the feeder line (such as feeder line 1) that has a single-phase ground fault in each feeder line connected to the first busbar can be expressed by the above formula (2).

[0077] It is understandable that when a high-resistance ground fault occurs, since the first zero-sequence current of the ground fault line is small, the target bus tie switch is closed in a short time, and the grounding capacitor current of the second bus flows into the first zero-sequence current of the ground fault line, which will not affect the stable operation of the power distribution system.

[0078] S204 detects ground fault lines based on the first and second zero-sequence currents of each feeder line.

[0079] One possible implementation of this step is as follows: determine whether the difference between the amplitude of the first zero-sequence current and the amplitude of the second zero-sequence current of each feeder line is within a preset measurement error range. If the difference between the amplitude of the first zero-sequence current and the amplitude of the second zero-sequence current is within the preset measurement error range, then it is determined that no single-phase grounding fault has occurred in the corresponding feeder line, and the feeder line is determined to be a non-grounding fault line. If the difference between the amplitude of the first zero-sequence current and the amplitude of the second zero-sequence current is not within the preset measurement error range, then it is determined that a single-phase grounding fault has occurred in the corresponding feeder line, and the feeder line is determined to be a grounding fault line.

[0080] In this embodiment, by employing a fault characteristic amplification mechanism linked by a bus tie switch, when the maximum first zero-sequence current in the first zero-sequence current of each feeder line connected to the first bus is less than a first preset current threshold, the target bus tie switch used to connect the first bus and the second bus adjacent to the first bus in a non-faulty state is closed. This causes the capacitive current of the second bus to flow through the target bus tie switch into the feeder line connected to the first bus in a ground fault state, increasing the first zero-sequence current of the feeder line in a ground fault state, improving the accuracy of selecting the feeder line in a ground fault state, and thus improving the accuracy of ground fault detection.

[0081] Optionally, step S204, based on the first zero-sequence current and the second zero-sequence current of each feeder line, may include the following steps: determining whether the first zero-sequence current and the second zero-sequence current of each feeder line meet preset conditions; if the first zero-sequence current and the second zero-sequence current of any feeder line meet the preset conditions, then the feeder line is determined to be a ground fault line.

[0082] For example, preset conditions can be expressed by the following formula:

[0083]

[0084] in, This represents the second zero-sequence current of feeder line k connected to the first busbar. This represents the first zero-sequence current of feeder line k connected to the first busbar, where k represents the index of the feeder line.

[0085] Understandably, this preset condition is used to verify the amplitude increments of the second zero-sequence current and the first zero-sequence current in order to further eliminate error interference and thus improve the accuracy of ground fault detection.

[0086] Optionally, the ground fault detection method for master station linkage provided in this application embodiment further includes: if the first zero-sequence current and the second zero-sequence current of any feeder line do not meet the preset conditions, then the feeder line is determined to be a non-ground fault line.

[0087] The preset conditions are similar to those described above, and will not be repeated here.

[0088] Optionally, the ground fault detection method for master station linkage provided in this application embodiment further includes: if the maximum first zero-sequence current is greater than or equal to the first preset current threshold, then the feeder line corresponding to the maximum first zero-sequence current is determined to be the ground fault line.

[0089] The specific implementation method is similar to that described above, and will not be repeated here.

[0090] Optionally, the ground fault detection method for master station linkage provided in this application embodiment further includes: dynamically adjusting the closing time of the target bus tie switch according to the load status of the distribution network system to which the first bus belongs and the fault characteristic change trend of the first bus.

[0091] For example, the load status of the distribution network system can be the overall characteristics of the power load (including residential, industrial, commercial and other types of loads) carried by the distribution network (including core equipment such as busbars, feeder lines and grounding transformers) to which the first busbar belongs during real-time operation, including load size, three-phase balance, and trend of change.

[0092] For example, the trend of fault characteristics can be dynamic features such as the rate of increase of zero-sequence current in a ground fault line.

[0093] One possible implementation of this step is to employ a dynamic timing control algorithm to dynamically adjust the closing time of the target bus tie switch based on the load status of the distribution network system to which the first bus belongs and the changing trend of the fault characteristics of the first bus. For example, when the load of the distribution network system is low or the increase in zero-sequence current of the ground fault line is small, the closing time is extended to ensure that the ground capacitance current of the non-faulty section bus (i.e., the second bus) is fully superimposed; when the load of the distribution network system is high or the increase in zero-sequence current of the ground fault line is significant, the closing time is shortened to reduce the impact on the distribution network system.

[0094] Understandably, this dynamic adjustment mechanism, based on real-time data feedback, addresses the potential risks to system stability posed by bus tie switch closing operations through synergistic optimization of minimizing closing time and maximizing fault feature amplification. In the master station-linked ground fault detection method provided in this application, dynamic optimization of the bus tie switch closing time at the timing level ensures sufficient amplification of fault features while avoiding the impact of prolonged closing on the stability of the distribution network system, thus achieving a dual improvement in ground fault detection efficiency and distribution network system security.

[0095] Optionally, one possible implementation of step S201, which involves obtaining the first zero-sequence current of each feeder line connected to the first bus, is as follows: when the bus zero-sequence voltage of the first bus is detected to be greater than a preset voltage threshold, and the first zero-sequence current of each feeder line is less than a second preset current threshold, the first zero-sequence current of each feeder line is obtained, wherein the second preset current threshold is greater than the first preset current threshold.

[0096] For example, the zero-sequence voltage of the first bus can be one-third of the vector sum of the three-phase phase voltages of the first bus in the distribution network to which the first bus belongs.

[0097] For example, the preset voltage threshold can be 2kV, etc. This application embodiment does not limit the size of the preset voltage threshold, and it can be determined according to the actual application requirements.

[0098] It is understandable that when the zero-sequence voltage of the first busbar is detected to be greater than the preset voltage threshold, it is determined that a single-phase grounding fault has occurred in the distribution network to which the first busbar belongs, and the first zero-sequence current acquisition of each feeder line connected to the first busbar is initiated.

[0099] For example, the first zero-sequence current of each feeder line can be obtained by the zero-sequence current transformer corresponding to each feeder line.

[0100] For example, the second preset current threshold can be a zero-sequence current protection action limit. That is, when the first zero-sequence current corresponding to any feeder line is greater than or equal to the first preset current threshold, the zero-sequence protection device configured on the feeder line will promptly perform a protection action (such as controlling the feeder line circuit breaker to trip) to isolate the feeder line from the distribution network. This application embodiment does not limit the size of the second preset current threshold; it can be determined according to actual application requirements.

[0101] For example, the determination of the first zero-sequence current and the second preset current threshold can be expressed by the following formula:

[0102]

[0103] in, This indicates the second preset current threshold.

[0104] It is understandable that when the transition resistance of a single-phase ground fault is small, i.e., a low-resistance ground fault, the first zero-sequence current of the ground fault line is usually greater than or equal to the second preset current threshold, meaning that the ground fault line can be detected by the second preset current threshold. When the transition resistance of a single-phase ground fault is large, i.e., a high-resistance ground fault, the first zero-sequence current of the ground fault line is usually less than the second preset current threshold, meaning that the ground fault line cannot be detected by the second preset current threshold.

[0105] For example, one possible implementation of this embodiment is as follows: when the zero-sequence voltage of the first busbar is detected to be greater than a preset voltage threshold, the zero-sequence protection devices configured on each feeder line connected to the first busbar begin to collect the first zero-sequence current of each feeder line respectively, and determine whether each first zero-sequence current is greater than or equal to a second preset current threshold. If at least one first zero-sequence current is greater than or equal to the second preset current threshold, the feeder line corresponding to at least one first zero-sequence current is identified as a ground fault line, and protection action is performed on the feeder line identified as a ground fault line. If the first zero-sequence current of each feeder line is less than the second preset current threshold, the first zero-sequence current of each feeder line is uploaded to the main station through the distribution terminal. The main station fault detection device receives the data and performs single-phase ground fault detection based on the first zero-sequence current of each feeder line.

[0106] Figure 3 A flowchart illustrating the grounding fault detection method for master station linkage provided in this application embodiment. Figure 2 .like Figure 3 As shown, a specific implementation of the ground fault detection method linked to the master station may include the following steps:

[0107] S301, when the zero-sequence voltage of the first busbar is detected to be greater than the preset voltage threshold, the first zero-sequence current on each feeder line connected to the first busbar is collected.

[0108] Understandably, this step is performed by the zero-sequence protection devices configured on each feeder line connected to the first busbar.

[0109] The specific implementation method is similar to that described above, and will not be repeated here.

[0110] S302, determine whether the first zero-sequence current of each feeder line is greater than or equal to the second preset current threshold.

[0111] In this step, the zero-sequence protection device determines whether the first zero-sequence current of each feeder line is greater than or equal to the second preset current threshold. If at least one first zero-sequence current is greater than or equal to the second preset current threshold, then step S303 is executed; if the first zero-sequence current of each feeder line is less than the second preset current threshold, then step S304 is executed.

[0112] S303 identifies at least one feeder line corresponding to the first zero-sequence current as a ground fault line and performs protection actions on the ground fault line.

[0113] S304 uploads the first zero-sequence current of each feeder line to the main station.

[0114] It is understood that steps S301 to S304 are performed by the zero-sequence protection devices configured on each feeder line connected to the first bus.

[0115] S305, determine whether the maximum first zero-sequence current in the first zero-sequence current of each feeder line is greater than or equal to the first preset current threshold.

[0116] In this step, it is determined whether the maximum first zero-sequence current in the first zero-sequence current of each feeder line is greater than or equal to the first preset current threshold. If the maximum first zero-sequence current is greater than or equal to the first preset current threshold, then step S306 is executed; if the maximum first zero-sequence current is less than the first preset current threshold, then step S307 is executed.

[0117] S306, determine that the feeder line corresponding to the maximum first zero-sequence current is the ground fault line.

[0118] S307 controls the closing of the target bus tie switch and obtains the second zero-sequence current of each feeder line.

[0119] The specific implementation method is similar to that described above, and will not be repeated here.

[0120] S308, determine whether the first zero-sequence current and the second zero-sequence current of each feeder line meet the preset conditions.

[0121] In this step, it is determined whether the first zero-sequence current and the second zero-sequence current of each feeder line meet the preset conditions. If the first zero-sequence current and the second zero-sequence current of any feeder line meet the preset conditions, then step S309 is executed; if the first zero-sequence current and the second zero-sequence current of any feeder line do not meet the preset conditions, then the feeder line is determined to be a non-grounding fault line.

[0122] S309 indicates that the feeder line is a ground fault line.

[0123] S310 sends a protection action signal to the zero-sequence protection device of the ground fault line so that the zero-sequence protection device of the ground fault line performs protection action.

[0124] The specific implementation method is similar to that described above, and will not be repeated here.

[0125] Understandably, steps S305 to S310 are executed through the main station.

[0126] The ground fault detection method with master station linkage provided in this application first detects low-resistance ground fault scenarios based on a second preset current threshold, enabling rapid action on low-resistance ground faults. Second, when the ground fault is not a low-resistance ground fault, i.e., the ground fault line cannot be accurately detected based on the second preset current threshold, ground fault detection is further performed based on a first preset current threshold. Then, when the ground fault line cannot be accurately detected based on the first preset current threshold, the target bus tie switch is closed, and ground fault analysis is performed based on the incremental verification of the first and second zero-sequence current amplitudes of each feeder line. On the one hand, this achieves three-stage coordinated ground fault detection for different ground fault scenarios; on the other hand, for high-resistance ground fault scenarios, a fault feature amplification mechanism with bus tie switch linkage is used for ground fault detection, improving the accuracy of ground fault detection.

[0127] The following are embodiments of the apparatus described in this application, which can be used to execute the embodiments of the method described in this application. For details not disclosed in the apparatus embodiments of this application, please refer to the embodiments of the method described in this application.

[0128] Figure 4 This is a schematic diagram of the grounding fault detection device for master station linkage provided in an embodiment of this application. Figure 4 As shown, the ground fault detection device 40 linked to the main station includes an acquisition module 410, a determination module 420, a processing module 430, and a detection module 440.

[0129] The acquisition module 410 is used to acquire the first zero-sequence current of each feeder line connected to the first busbar.

[0130] The determination module 420 is used to determine whether the maximum first zero-sequence current in the first zero-sequence current of each feeder line is greater than or equal to a first preset current threshold.

[0131] The processing module 430 is used to control the target bus tie switch to close when the maximum first zero-sequence current is less than the first preset current threshold, and to obtain the second zero-sequence current of each feeder line. The target bus tie switch is used to connect the first bus and the second bus, and the second bus is the bus adjacent to the first bus and in a non-faulty state.

[0132] The detection module 440 is used to detect ground fault lines based on the first zero-sequence current and the second zero-sequence current of each feeder line.

[0133] In one possible implementation, the detection module 440 is specifically used to: determine whether the first zero-sequence current and the second zero-sequence current of each feeder line meet the preset conditions; if the first zero-sequence current and the second zero-sequence current of any feeder line meet the preset conditions, then the feeder line is determined to be a ground fault line.

[0134] In one possible implementation, the detection module 440 is further configured to: determine that a feeder line is a non-grounded fault line when the first zero-sequence current and the second zero-sequence current of any feeder line do not meet the preset conditions.

[0135] In one possible implementation, the determining module 420 is further configured to: determine the feeder line corresponding to the maximum first zero-sequence current as a ground fault line when the maximum first zero-sequence current is greater than or equal to a first preset current threshold.

[0136] In one possible implementation, the ground fault detection device linked to the master station also includes a dynamic adjustment module (not shown), which is used to dynamically adjust the closing time of the target bus tie switch according to the load status of the distribution network system to which the first bus belongs and the changing trend of the fault characteristics of the first bus.

[0137] In one possible implementation, the acquisition module 410 is specifically used to: acquire the first zero-sequence current of each feeder line when the bus zero-sequence voltage of the first bus is detected to be greater than a preset voltage threshold and the first zero-sequence current of each feeder line is less than a second preset current threshold.

[0138] The ground fault detection device for master station linkage provided in this embodiment can be used to execute the method steps of the above method embodiment. The specific implementation and technical effects are similar, and will not be repeated here.

[0139] Figure 5 This is a schematic diagram of the structure of an electronic device provided in an embodiment of this application. Figure 5 As shown, the electronic device 50 provided in this embodiment includes at least one processor 501 and a memory 502. Optionally, the electronic device 50 further includes a communication component 503. The processor 501, memory 502, and communication component 503 are connected via a bus 504.

[0140] In a specific implementation, at least one processor 501 executes computer execution instructions stored in memory 502, causing at least one processor 501 to perform the above-described method.

[0141] The specific implementation process of processor 501 can be found in the above method embodiments, and its implementation principle and technical effect are similar. It will not be repeated here.

[0142] In the above embodiments, it should be understood that the processor can be a Central Processing Unit (CPU), or other general-purpose processors, digital signal processors (DSPs), application-specific integrated circuits (ASICs), etc. The general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in this invention can be directly implemented by a hardware processor, or implemented by a combination of hardware and software modules within the processor.

[0143] The memory may include random access memory (RAM) and non-volatile memory (NVM), such as at least one disk storage device.

[0144] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. Buses can be categorized as address buses, data buses, control buses, etc. For ease of illustration, the buses shown in the accompanying drawings are not limited to a single bus or a single type of bus.

[0145] This application also provides a computer program product, including a computer program that, when executed by a processor, implements the above-described method.

[0146] This application also provides a computer-readable storage medium storing computer-executable instructions, which, when executed by a processor, implement the above-described method.

[0147] The aforementioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic storage, flash memory, magnetic disk, or optical disk. The readable storage medium can be any available medium accessible to a general-purpose or special-purpose computer.

[0148] An exemplary readable storage medium is coupled to a processor, enabling the processor to read information from and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can reside in an Application Specific Integrated Circuit (ASIC). Alternatively, the processor and the readable storage medium can exist as discrete components in the device.

[0149] The division of units is merely a logical functional division; in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be indirect coupling or communication connection through some interfaces, devices, or units, and may be electrical, mechanical, or other forms.

[0150] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0151] In addition, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0152] If a function is implemented as 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 this invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods of the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0153] Those skilled in the art will understand that all or part of the steps of the above-described method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When executed, the program performs the steps of the above-described method embodiments; and the aforementioned storage medium includes various media capable of storing program code, such as ROM, RAM, magnetic disks, or optical disks.

[0154] Finally, it should be noted that other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This invention is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein, and is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

Claims

1. A grounding fault detection method with master station linkage, characterized in that, include: Obtain the first zero-sequence current of each feeder line connected to the first busbar; Determine whether the maximum first zero-sequence current in the first zero-sequence current of each feeder line is greater than or equal to a first preset current threshold. If the maximum first zero-sequence current is less than the first preset current threshold, the target bus tie switch is controlled to close, and the second zero-sequence current of each feeder line is obtained. The target bus tie switch is used to connect the first bus and the second bus. The second bus is a bus adjacent to the first bus that is in a non-faulty state. The ground fault line is detected based on the first zero-sequence current and the second zero-sequence current of each feeder line.

2. The grounding fault detection method according to claim 1, characterized in that, The step of detecting ground fault lines based on the first zero-sequence current and the second zero-sequence current of each feeder line includes: Determine whether the first zero-sequence current and the second zero-sequence current of each feeder line meet the preset conditions. If the first zero-sequence current and the second zero-sequence current of any feeder line meet the preset conditions, then the feeder line is determined to be the ground fault line.

3. The grounding fault detection method according to claim 2, characterized in that, Also includes: If the first zero-sequence current and the second zero-sequence current of any feeder line do not meet the preset conditions, then the feeder line is determined to be a non-grounded fault line.

4. The ground fault detection method according to any one of claims 1 to 3, characterized in that, Also includes: If the maximum first zero-sequence current is greater than or equal to the first preset current threshold, then the feeder line corresponding to the maximum first zero-sequence current is determined to be the ground fault line.

5. The ground fault detection method according to any one of claims 1 to 3, characterized in that, Also includes: The closing time of the target bus tie switch is dynamically adjusted based on the load status of the distribution network system to which the first bus belongs and the changing trend of the fault characteristics of the first bus.

6. The ground fault detection method according to any one of claims 1 to 3, characterized in that, The step of obtaining the first zero-sequence current of each feeder line connected to the first busbar includes: When the zero-sequence voltage of the first busbar is detected to be greater than a preset voltage threshold, and the first zero-sequence current of each feeder line is less than a second preset current threshold, the first zero-sequence current of each feeder line is obtained, wherein the second preset current threshold is greater than the first preset current threshold.

7. A grounding fault detection device with master station linkage, characterized in that, include: The acquisition module is used to acquire the first zero-sequence current of each feeder line connected to the first busbar. The determination module is used to determine whether the maximum first zero-sequence current in the first zero-sequence current of each feeder line is greater than or equal to a first preset current threshold. The processing module is used to control the target bus tie switch to close when the maximum first zero-sequence current is less than the first preset current threshold, and to obtain the second zero-sequence current of each feeder line. The target bus tie switch is used to connect the first bus and the second bus, and the second bus is a bus adjacent to the first bus that is in a non-fault state. The detection module is used to detect ground fault lines based on the first zero-sequence current and the second zero-sequence current of each feeder line.

8. An electronic device, characterized in that, include: A processor, and a memory communicatively connected to the processor; The memory stores computer-executed instructions; The processor executes the computer execution instructions stored in the memory to implement the ground fault detection method for master station linkage as described in any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer-executable instructions, which, when executed by a processor, are used to implement the ground fault detection method for master station linkage as described in any one of claims 1 to 6.

10. A computer program product, characterized in that, include: A computer program, when executed by a processor, implements the ground fault detection method for master station linkage as described in any one of claims 1 to 6.

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