Fault detection method, device and electronic equipment of power system

Abstract

This invention discloses a method, apparatus, and electronic device for fault detection in power systems. The method includes: in response to a power system fault, connecting a preset resistor to the power system and acquiring the zero-sequence voltage of the power system bus and multiple zero-sequence currents at multiple monitoring points in the power system, wherein the preset resistor is connected in parallel with the neutral point of the power system; projecting the multiple zero-sequence currents onto the zero-sequence voltage of the bus to obtain steady-state projections of the multiple zero-sequence currents; determining the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points based on the steady-state projections of the multiple zero-sequence currents; and determining the faulty section from multiple sections of the power system based on the locations of the multiple monitoring points and the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points, wherein the multiple sections are obtained by dividing the power system lines using multiple monitoring points. This invention solves the technical problem of the high difficulty in locating power system faults.

Description

Technical Field

[0001] This invention relates to the field of power systems, and more specifically, to a fault detection method, apparatus, and electronic equipment for power systems. Background Technology

[0002] For flexible grounding systems, transient feature methods, such as wavelet methods and energy methods, can be used to locate the fault when a fault occurs. However, in some scenarios, such as high-resistance grounding faults, the fault feature quantities are relatively weak, making it difficult to accurately extract the fault feature quantities using transient feature methods, thus making it difficult to locate the system fault.

[0003] There is currently no effective solution to the above problems. Summary of the Invention

[0004] This invention provides a method, apparatus, and electronic device for detecting faults in power systems, thereby addressing the technical challenge of locating faults in power systems.

[0005] According to one aspect of the present invention, a fault detection method for a power system is provided, comprising: in response to a fault in the power system, connecting a preset resistor to the power system and acquiring the zero-sequence voltage of the power system bus and multiple zero-sequence currents at multiple monitoring points in the power system, wherein the preset resistor is connected in parallel with the neutral point of the power system; projecting the multiple zero-sequence currents onto the zero-sequence voltage of the bus to obtain steady-state projections of the multiple zero-sequence currents; determining a correlation coefficient between the zero-sequence currents at any two adjacent monitoring points based on the steady-state projections of the multiple zero-sequence currents; and determining a fault section from multiple sections of the power system based on the locations of the multiple monitoring points and the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points, wherein the multiple sections are obtained by dividing the power system lines through multiple monitoring points.

[0006] Optionally, multiple zero-sequence currents are projected onto the bus zero-sequence voltage to obtain the steady-state projection of the multiple zero-sequence currents, including: for any one of the multiple zero-sequence currents, converting the bus zero-sequence voltage into a voltage vector and the zero-sequence current into a current vector; determining the vector angle between the voltage vector and the current vector; and determining the steady-state projection of the zero-sequence current based on the voltage vector, the current vector, and the vector angle.

[0007] Optionally, based on the location of multiple monitoring points and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points, the fault section is determined from multiple sections of the power system, including: determining the line type of the power system; and determining the fault section from multiple sections of the power system based on the line type, the location of multiple monitoring points, and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points.

[0008] Optionally, based on the line type, the location of multiple monitoring points, and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points, a fault section is determined from multiple sections of the power system, including: when the line type is a non-branch line, two target monitoring points are determined from multiple monitoring points based on the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points, wherein the two target monitoring points are adjacent monitoring points and the correlation coefficient between the zero-sequence currents on the two target monitoring points is negative; and the section between the two target monitoring points is determined as the fault section.

[0009] Optionally, the method further includes determining the last segment along the current direction from multiple segments as the fault segment, provided that the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points is positive.

[0010] Optionally, based on the line type, the locations of multiple monitoring points, and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points, a fault section is determined from multiple sections of the power system. This includes: when the line type is a branch line, determining a first monitoring point and a second monitoring point from multiple monitoring points, wherein the first monitoring point is located on the main line of the power system and is adjacent to monitoring points on multiple branch lines, and the second monitoring point is located on any one of the branch lines and is adjacent to the first monitoring point; in response to the fact that the correlation coefficient between the zero-sequence currents on the first monitoring point and the second monitoring point are both negative, and the absolute value of the correlation coefficient between the zero-sequence currents on the first monitoring point and the second monitoring point is within a preset range, determining the section between the first monitoring point and the second monitoring point as the fault section.

[0011] Optionally, multiple zero-sequence currents at multiple monitoring points in a power system can be acquired, including: acquiring multiple zero-sequence currents through phasor measurement units installed at multiple monitoring points.

[0012] Optionally, in the case where the power system includes multiple branch lines, the multiple monitoring points include: at least one monitoring point set on the main line of the power system, and at least one monitoring point set on each branch line.

[0013] According to another aspect of the present invention, a fault detection device for a power system is also provided, comprising: an acquisition module, configured to, in response to a fault in the power system, connect a preset resistor to the power system and acquire the zero-sequence voltage of the power system bus and multiple zero-sequence currents at multiple monitoring points in the power system, wherein the preset resistor is connected in parallel with the neutral point of the power system; a projection module, configured to project the multiple zero-sequence currents onto the zero-sequence voltage of the bus, respectively, to obtain the steady-state projection of the multiple zero-sequence currents; and to determine a correlation coefficient between the zero-sequence currents at any two adjacent monitoring points based on the steady-state projection of the multiple zero-sequence currents; a first determination module, configured to determine the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points based on the steady-state projection of the multiple zero-sequence currents; and a second determination module, configured to determine a faulty section from multiple sections of the power system based on the locations of the multiple monitoring points and the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points, wherein the multiple sections are obtained by dividing the power system lines through multiple monitoring points.

[0014] According to another aspect of the present invention, an electronic device is also provided, comprising: a memory storing an executable program; and a processor for running the program, wherein the program executes the above-described power system fault detection method during runtime.

[0015] According to another aspect of the present invention, a computer-readable storage medium is also provided, the computer-readable storage medium including a stored executable program, wherein, when the executable program is executed, it controls the device where the storage medium is located to execute the above-described power system fault detection method.

[0016] According to another aspect of the present invention, a computer program product is also provided, including a computer program that, when executed by a processor, implements the above-described power system fault detection method.

[0017] In this embodiment of the invention, in response to a power system fault, a preset resistor is connected to the power system, and the zero-sequence voltage of the power system bus and multiple zero-sequence currents at multiple monitoring points in the power system are obtained. The multiple zero-sequence currents are projected onto the zero-sequence voltage of the bus to obtain the steady-state projection of the multiple zero-sequence currents. Based on the steady-state projection of the multiple zero-sequence currents, the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points is determined. Based on the location of multiple monitoring points and the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points, the faulty section is determined from multiple sections of the power system. It is noteworthy that by determining the steady-state projection of the multiple zero-sequence currents at different monitoring points onto the zero-sequence voltage of the bus, the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points can be further determined, thereby judging the correlation between the upstream and downstream zero-sequence currents of any section. Based on the correlation coefficient, the section where the fault occurred is determined, achieving the purpose of locating the fault location, and thus solving the technical problem of the high difficulty in locating power system faults. Attached Figure Description

[0018] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this application, illustrate exemplary embodiments of the invention and, together with their description, serve to explain the invention and do not constitute an undue limitation thereof. In the drawings:

[0019] Figure 1 This is a flowchart of a fault detection method for a power system according to an embodiment of the present invention;

[0020] Figure 2 This is a schematic diagram of an optional branchless circuit according to an embodiment of the present invention;

[0021] Figure 3 This is a schematic diagram of an optional branched circuit according to an embodiment of the present invention;

[0022] Figure 4 This is a flowchart of an optional fault detection method according to an embodiment of the present invention;

[0023] Figure 5 This is a schematic diagram of a fault detection device for a power system according to an embodiment of the present invention. Detailed Implementation

[0024] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0025] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0026] Example 1

[0027] According to an embodiment of the present invention, a fault detection method for a power system is provided. It should be noted that the steps shown in the flowchart in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowchart, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0028] Figure 1 This is a flowchart of a power system fault detection method according to an embodiment of the present invention, such as... Figure 1 As shown, the method includes the following steps:

[0029] In step S102, in response to a power system fault, a preset resistor is connected to the power system, and the zero-sequence voltage of the power system bus and multiple zero-sequence currents at multiple monitoring points in the power system are obtained, wherein the preset resistor is connected in parallel with the neutral point of the power system.

[0030] The preset resistor in the above steps is a pre-set resistor. The specific resistance value of the preset resistor can be preset according to the actual application situation, and there is no restriction on the specific resistance value of the preset resistor here. Connect the preset resistor to the power system and connect it in parallel with the neutral point of the power system. The neutral point is the common point connecting the three-phase voltage sources in the AC power system. After connecting the preset resistor in parallel with the neutral point, the zero-sequence current upstream of the fault point increases with resistive component compared with before the preset resistor was connected. However, the zero-sequence current downstream of the fault point is not affected by the parallel preset resistor. Therefore, after connecting the preset resistor in parallel with the neutral point, the relationship between the zero-sequence current upstream and downstream of the monitoring point can be used to determine whether there is a fault in the section between the monitoring points.

[0031] The zero-sequence voltage mentioned in the above steps refers to the zero-sequence voltage generated on the busbar of a power system due to unbalanced current or fault conditions. Zero-sequence voltage is the voltage generated during a power system fault. In a three-phase power system, the three-phase voltages are symmetrical under normal conditions, and no zero-sequence voltage exists. However, when a ground fault occurs in the system, such as a single-phase ground fault, due to asymmetry, a voltage will be generated at the zero-sequence point of the system, i.e., the neutral point. This voltage is called zero-sequence voltage.

[0032] The monitoring points in the above steps are points that monitor zero-sequence current, and these monitoring points divide the power system into multiple sections.

[0033] The zero-sequence current mentioned above is the current generated during a power system fault. In a normal three-phase power system, the three-phase currents are symmetrical, and the vector sum of the three-phase currents is zero at any given time, so there is no zero-sequence current. However, when a ground fault occurs in the power system, due to the asymmetry of the system, the vector sum of the three-phase currents is no longer zero, thus generating a zero-sequence current.

[0034] In one optional embodiment, after a power system fault occurs, the fault location device in the power system activates beyond the limit after detecting that the zero-sequence voltage exceeds a threshold. It closes the preset resistor switching switch in the power system, connecting the preset resistor into the circuit so that the preset resistor is connected in parallel with the neutral point. The preferred value of the preset resistor is 10 ohms, but other resistance values ​​can be selected as the preset resistor depending on the actual application. The resistance value of the preset resistor is not limited to 10 ohms.

[0035] When acquiring the zero-sequence voltage of the power system bus and the zero-sequence current at multiple monitoring points in the power system, a zero-sequence voltage sensor can be installed on the power system bus, and a zero-sequence current sensor can be installed at each monitoring point in the power system. The zero-sequence voltage of the power system bus is acquired through the zero-sequence voltage sensor, and the zero-sequence current at the monitoring point is acquired through the zero-sequence current sensor.

[0036] In another alternative embodiment, a zero-sequence voltmeter can be used to obtain the bus zero-sequence voltage. A phasor measurement unit (PMU) can be installed at each monitoring point to obtain the zero-sequence current at that point. It should be noted that the zero-sequence current changes over time; therefore, a zero-sequence current acquisition period can be designed to collect the zero-sequence current within one period and express it as a function of time.

[0037] Step S104: Project the multiple zero-sequence currents onto the bus zero-sequence voltage respectively to obtain the steady-state projection of the multiple zero-sequence currents.

[0038] The steady-state projection quantity in the above steps is the projection component of the zero-sequence current onto the zero-sequence voltage of the bus. By projecting the zero-sequence current onto the zero-sequence voltage, the steady-state component reflecting the fault characteristics can be extracted, which helps to more accurately identify and locate the fault.

[0039] In one optional embodiment, the power system has multiple monitoring points. A zero-sequence current is acquired from each monitoring point, and each zero-sequence current is projected onto the bus zero-sequence voltage to obtain a steady-state projection quantity, thus obtaining multiple steady-state projection quantities. When projecting the zero-sequence current onto the bus zero-sequence voltage, the inner product of the bus zero-sequence voltage and the zero-sequence current is calculated, and the unit vector of the bus zero-sequence voltage is calculated. Based on the inner product of the bus zero-sequence voltage and the zero-sequence current, and the unit vector of the bus zero-sequence voltage, the steady-state projection quantity of the bus zero-sequence voltage is determined.

[0040] Step S106: Determine the correlation coefficient between zero-sequence currents at any two adjacent monitoring points based on the steady-state projections of multiple zero-sequence currents.

[0041] The correlation coefficient in the above steps is used to assess the degree of correlation between the zero-sequence currents at any two adjacent monitoring points. It can be the Pearson correlation coefficient, but is not limited to it. The calculated correlation coefficient ranges from -1 to 1 (a closed interval). When the correlation coefficient is greater than 0, the zero-sequence currents at two adjacent monitoring points are positively correlated; when the correlation coefficient is less than 0, the zero-sequence currents at two adjacent monitoring points are negatively correlated. When the absolute value of the correlation coefficient is equal to 1, it indicates that the zero-sequence currents at two adjacent monitoring points are perfectly correlated, meaning the zero-sequence currents at the two adjacent monitoring points are completely identical. When the correlation coefficient is equal to zero, it indicates that the zero-sequence currents at two adjacent monitoring points are completely independent and have no correlation. When the absolute value of the correlation coefficient is between 0 and 1, it indicates that the zero-sequence currents at two adjacent monitoring points have a certain correlation. The closer the absolute value of the correlation coefficient is to 1, the higher the correlation between the zero-sequence currents at two adjacent monitoring points; the closer the absolute value of the correlation coefficient is to 0, the lower the correlation between the zero-sequence currents at two adjacent monitoring points.

[0042] In an optional embodiment, the correlation coefficient between the zero-sequence currents at two adjacent monitoring points can be calculated based on the steady-state projection of the zero-sequence currents at the two adjacent monitoring points. The calculation formula is as follows:

[0043]

[0044] Where, r ij I represents the correlation coefficient between the zero-sequence currents at two adjacent monitoring points, where t is time, T is the period for acquiring the zero-sequence current, and I is the zero-sequence current. i.P (t) represents the steady-state projection of the zero-sequence current at monitoring point i, I j.P(t)dt is the steady-state projection of the zero-sequence current at monitoring point j. Monitoring point i is adjacent to monitoring point j. The zero-sequence current is a quantity that changes continuously with time t. Therefore, the steady-state projection of the zero-sequence current is a function of time t and can be integrated.

[0045] Step S108: Based on the location of multiple monitoring points and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points, the fault section is determined from multiple sections of the power system. The multiple sections are obtained by dividing the power system lines through multiple monitoring points.

[0046] The faulty section in the above steps refers to the section of the power system where a fault exists, and can be determined based on the sign of the correlation coefficient.

[0047] In one optional embodiment, for unbranched sections, every two monitoring points form a section. The sign of the correlation coefficient between two adjacent monitoring points determines whether the section between the two adjacent monitoring points is a faulty section. For branched sections, the method for determining whether a section is a faulty section is the same as for unbranched sections, excluding the branch points. However, in sections containing branch points, the monitoring points on the main line and multiple monitoring points on adjacent branch lines form a section. When determining whether this section is a faulty section, a correlation coefficient is calculated between the zero-sequence current corresponding to the monitoring point on the main line and the zero-sequence current corresponding to the monitoring point on each branch line. The sign of multiple correlation coefficients is used to determine whether the section is a faulty section.

[0048] In this embodiment of the invention, in response to a power system fault, a preset resistor is connected to the power system, and the zero-sequence voltage of the power system bus and multiple zero-sequence currents at multiple monitoring points in the power system are obtained. The multiple zero-sequence currents are projected onto the zero-sequence voltage of the bus to obtain the steady-state projection of the multiple zero-sequence currents. Based on the steady-state projection of the multiple zero-sequence currents, the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points is determined. Based on the location of multiple monitoring points and the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points, the faulty section is determined from multiple sections of the power system. It is noteworthy that by determining the steady-state projection of the multiple zero-sequence currents at different monitoring points onto the zero-sequence voltage of the bus, the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points can be further determined, thereby judging the correlation between the upstream and downstream zero-sequence currents of any section. Based on the correlation coefficient, the section where the fault occurred is determined, achieving the purpose of locating the fault location, and thus solving the technical problem of the high difficulty in locating power system faults.

[0049] Optionally, multiple zero-sequence currents are projected onto the bus zero-sequence voltage to obtain the steady-state projection of the multiple zero-sequence currents, including: for any one of the multiple zero-sequence currents, converting the bus zero-sequence voltage into a voltage vector and the zero-sequence current into a current vector; determining the vector angle between the voltage vector and the current vector; and determining the steady-state projection of the zero-sequence current based on the voltage vector, the current vector, and the vector angle.

[0050] In the above steps, the voltage vector is the zero-sequence voltage of the bus in vector form, and the current vector is the zero-sequence current in vector form. The vector form can better describe the relative relationship between the zero-sequence voltage and zero-sequence current of the bus in the power system, which is convenient for analysis and calculation.

[0051] The vector angle in the above steps is the angle between the voltage vector and the current vector, used to describe the directional relationship between the voltage vector and the current vector.

[0052] In one optional embodiment, it is necessary to calculate the steady-state projection vector between the zero-sequence current and the bus zero-sequence voltage at each monitoring point. When calculating the steady-state projection vector between the zero-sequence current and the bus zero-sequence voltage, the bus zero-sequence voltage is converted into a voltage vector, and the zero-sequence current is converted into a current vector. The vector angle between the voltage vector and the current vector is measured, and then the magnitude of the projection of the current vector onto the voltage vector is calculated. The calculation formula is as follows:

[0053]

[0054] Where P is the magnitude of the projection of the current vector onto the voltage vector. Let I be the angle between the vectors, and let I be the magnitude of the current vector.

[0055] Then, based on the magnitude of the projection of the current vector onto the voltage vector and the unit vector of the voltage vector, the steady-state projection of the zero-sequence current is calculated using the following formula:

[0056]

[0057] in, Let P be the steady-state projection of the zero-sequence current, and let P be the magnitude of the projection of the current vector onto the voltage vector. Let U be the voltage vector, and U be the magnitude of the voltage vector. The ratio of |U| to the voltage vector is the unit vector.

[0058] Combining the two formulas above, the formula for calculating the steady-state projection of the zero-sequence current can be obtained as follows:

[0059]

[0060] in, This is the steady-state projection of the zero-sequence current. It is the inner product of the voltage vector and the current vector. Let U be the voltage vector, and U be the magnitude of the voltage vector. The ratio of |U| to the voltage vector is the unit vector.

[0061] Optionally, based on the location of multiple monitoring points and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points, the fault section is determined from multiple sections of the power system, including: determining the line type of the power system; and determining the fault section from multiple sections of the power system based on the line type, the location of multiple monitoring points, and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points.

[0062] The line types mentioned in the above steps refer to the types of lines in a power system. They can be classified according to whether they have branch lines or not, into lines without branches and lines with branches. They can also be classified according to voltage level, into high-voltage lines, medium-voltage lines, and low-voltage lines. They can also be classified according to the current they carry, into main lines, branch lines, and terminal lines, but these are not the only classifications.

[0063] In one optional embodiment, power lines are classified into non-branching lines and branching lines based on whether they have branches. Since branching lines contain branches, the setting of monitoring points at the branch points is more specific, requiring monitoring points to be set on both the main line and the branch line, with each monitoring point defining an area encompassing the branch point. Because the location of the monitoring points determines the various sections of the power system, and the location of monitoring points differs depending on the line type, determining the faulty section requires not only the correlation coefficient between the zero-sequence currents of any two adjacent monitoring points, but also the line type and the location of the monitoring points to pinpoint the faulty section.

[0064] Optionally, based on the line type, the location of multiple monitoring points, and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points, a fault section is determined from multiple sections of the power system, including: when the line type is a non-branch line, two target monitoring points are determined from multiple monitoring points based on the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points, wherein the two target monitoring points are adjacent monitoring points and the correlation coefficient between the zero-sequence currents on the two target monitoring points is negative; and the section between the two target monitoring points is determined as the fault section.

[0065] The "no branch line" in the above steps refers to a line with only one main line and no branch lines.

[0066] The two target detection points in the above steps are adjacent and can identify a section. Each section of the branchless line corresponds to two target monitoring points. The correlation coefficient between the zero-sequence currents on the two target monitoring points can be used to determine whether the section between the two target monitoring points is a fault section.

[0067] In one alternative embodiment, Figure 2 This is a schematic diagram of an optional branchless circuit according to an embodiment of the present invention, such as... Figure 2 As shown, the arrows indicate the direction of the current. Monitoring points 1, 2, and 3 are all monitoring points on a branchless line. Section 1 and Section 2 are two of several sections divided by the monitoring points. Specifically, the two target monitoring points corresponding to Section 1 are Monitoring Point 1 and Monitoring Point 2. If the correlation coefficient between the zero-sequence currents at Monitoring Point 1 and Monitoring Point 2 is negative, it indicates that the zero-sequence currents at Monitoring Point 1 and Monitoring Point 2 are negatively correlated and will not affect each other. Therefore, Section 1 is determined to be the fault section.

[0068] Optionally, the method further includes determining the last segment along the current direction from multiple segments as the fault segment, provided that the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points is positive.

[0069] In one alternative embodiment, Figure 2 This is a schematic diagram of an optional branchless circuit according to an embodiment of the present invention, such as... Figure 2 As shown, if Figure 2 If the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points is positive, then the last segment along the current direction, i.e., segment 2, can be identified as the fault segment.

[0070] Optionally, based on the line type, the locations of multiple monitoring points, and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points, a fault section is determined from multiple sections of the power system. This includes: when the line type is a branch line, determining a first monitoring point and a second monitoring point from multiple monitoring points, wherein the first monitoring point is located on the main line of the power system and is adjacent to monitoring points on multiple branch lines, and the second monitoring point is located on any one of the branch lines and is adjacent to the first monitoring point; in response to the fact that the correlation coefficient between the zero-sequence currents on the first monitoring point and the second monitoring point are both negative, and the absolute value of the correlation coefficient between the zero-sequence currents on the first monitoring point and the second monitoring point is within a preset range, determining the section between the first monitoring point and the second monitoring point as the fault section.

[0071] The preset range in the above steps is a pre-set numerical range. An preferred value of the preset range is a closed interval from -0.9 to -1, but it is not limited to this. It can be preset according to the actual application. Here, the specific value of the preset range is not restricted.

[0072] In one alternative embodiment, Figure 3 This is a schematic diagram of an optional branched circuit according to an embodiment of the present invention, such as... Figure 3 As shown, the arrows indicate the direction of the current. Monitoring points 1, 2, and 3 are all monitoring points on branch lines. Monitoring point 1 is located on the main line, while monitoring points 2 and 3 are located on branch lines. Monitoring points 1 and 2 are adjacent to each other, and monitoring points 3 are also adjacent to each other. Therefore, monitoring point 1 is designated as the first monitoring point, and monitoring points 2 and 3 as the second monitoring points. The section formed by monitoring points 1, 2, and 3 is designated as section 1. When the correlation coefficient between the zero-sequence currents at monitoring points 1 and 2 is negative and within a preset range, and the correlation coefficient between the zero-sequence currents at monitoring points 1 and 3 is also negative and within a preset range, the section between the first and second monitoring points, i.e., section 1, is determined to be the fault section.

[0073] Optionally, multiple zero-sequence currents at multiple monitoring points in a power system can be acquired, including: acquiring multiple zero-sequence currents through phasor measurement units installed at multiple monitoring points.

[0074] The phasor measurement unit in the above steps can be a PMU. A PMU is constructed using the second pulse of the Global Positioning System (GPS) as a synchronization clock. It can be used in the fields of dynamic monitoring, system protection, system analysis and prediction of power systems. It is an important device to ensure the safe operation of the power grid.

[0075] In one optional embodiment, a phasor measurement unit is installed at each monitoring point and debugged to ensure accurate measurement of the zero-sequence current. These phasor measurement units are then connected to a data acquisition system, which can be a centralized data acquisition device connected to each phasor measurement unit via a network or wireless communication. By connecting multiple phasor measurement units to the data acquisition system, multiple zero-sequence current data from multiple monitoring points can be collected simultaneously, and the data can be analyzed and processed.

[0076] Optionally, in the case where the power system includes multiple branch lines, the multiple monitoring points include: at least one monitoring point set on the main line of the power system, and at least one monitoring point set on each branch line.

[0077] In an optional embodiment, when the power system includes multiple branch lines, the main line is connected to multiple branch lines at the branch point. At least one monitoring point needs to be set on the main line and at least one monitoring point needs to be set on each branch line, so that the monitoring point on the main line is adjacent to the monitoring point on each branch line, thereby determining the fault status of the section including the branch point based on the collected zero-sequence current.

[0078] The following description uses a preferred embodiment. Figure 4 This is a flowchart of an optional fault detection method according to an embodiment of the present invention, such as... Figure 4 As shown, we can first determine whether the bus zero-sequence voltage is greater than the threshold. If not, it indicates that there is no fault in the power system, and we continue to monitor whether the bus zero-sequence voltage is greater than the threshold. If yes, it indicates that there is a fault in the power system, and we continue with the following steps. Then, we collect the bus zero-sequence voltage and the zero-sequence current at the monitoring points. Based on the collected fault information, we calculate the projected components of each zero-sequence current. The collected fault information is the bus zero-sequence voltage and the zero-sequence current at the monitoring points, and the projected components are the steady-state projected quantities mentioned above. Then, we calculate the correlation coefficients of the projected components corresponding to adjacent zero-sequence currents and compare the obtained correlation coefficients. Next, we determine whether the line has branches. If so, we need to determine whether the section is a faulty section based on the multiple correlation coefficients corresponding to the section. We determine the multiple correlation coefficients corresponding to the zero-sequence current at the monitoring points on the main line and the zero-sequence current at the monitoring points on multiple branch lines. We determine whether the section is a faulty section based on the sign and absolute value of the multiple correlation coefficients. If not, we determine whether the section is a faulty section based on one correlation coefficient corresponding to the section. We determine whether the section is a faulty section based on the correlation coefficients corresponding to the zero-sequence currents at the two monitoring points at the left and right ends of the section. Then the process ends.

[0079] Example 2

[0080] According to an embodiment of the present invention, an embodiment of a fault detection method device for a power system is provided. This device can execute the fault detection method for a power system provided in Embodiment 1 above. The specific implementation method and preferred application scenario are the same as those in Embodiment 1 above, and will not be repeated here.

[0081] Figure 5 This is a schematic diagram of a fault detection device for a power system according to an embodiment of the present invention, such as... Figure 5 As shown:

[0082] The acquisition module 50 is used to connect a preset resistor to the power system in response to a power system fault, and to acquire the bus zero-sequence voltage of the power system and multiple zero-sequence currents at multiple monitoring points in the power system, wherein the preset resistor is connected in parallel with the neutral point of the power system.

[0083] Projection module 52 is used to project multiple zero-sequence currents onto the bus zero-sequence voltage to obtain the steady-state projection of multiple zero-sequence currents; and to determine the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points based on the steady-state projection of multiple zero-sequence currents.

[0084] The first determining module 54 is used to determine the correlation coefficient between zero-sequence currents at any two adjacent monitoring points based on the steady-state projection of multiple zero-sequence currents.

[0085] The second determining module 56 is used to determine the fault section from multiple sections of the power system based on the location of multiple monitoring points and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points. The multiple sections are obtained by dividing the power system lines through multiple monitoring points.

[0086] Optionally, the projection module includes: a conversion unit, used to convert the bus zero-sequence voltage into a voltage vector and the zero-sequence current into a current vector for any one of the multiple zero-sequence currents; a first determining unit, used to determine the vector angle between the voltage vector and the current vector; and a second determining unit, used to determine the steady-state projection of the zero-sequence current based on the voltage vector, the current vector, and the vector angle.

[0087] Optionally, the second determining module includes: a third determining unit for determining the line type of the power system; and a fourth determining unit for determining the fault section from multiple sections of the power system based on the line type, the location of multiple monitoring points, and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points.

[0088] Optionally, the fourth determining unit is also used to determine two target monitoring points from multiple monitoring points based on the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points when the line type is a branchless line, wherein the two target monitoring points are adjacent monitoring points and the correlation coefficient between the zero-sequence currents on the two target monitoring points is negative; and to determine the section between the two target monitoring points as the fault section.

[0089] Optionally, the fourth determining unit is also used to determine the last segment along the current direction from multiple segments as the fault segment.

[0090] Optionally, the fourth determining unit is further configured to determine a first monitoring point and a second monitoring point from multiple monitoring points when the line type is a branch line, wherein the first monitoring point is located on the main line of the power system and is adjacent to the monitoring points on the multiple branch lines, and the second monitoring point is located on any one of the branch lines and is adjacent to the first monitoring point; in response to the fact that the correlation coefficient between the zero-sequence currents on the first monitoring point and the second monitoring point are both negative, and the absolute value of the correlation coefficient between the zero-sequence currents on the first monitoring point and the second monitoring point is within a preset range, the section between the first monitoring point and the second monitoring point is determined as a fault section.

[0091] Optionally, the acquisition unit is also used to acquire multiple zero-sequence currents through phasor measurement units installed at multiple monitoring points.

[0092] Optionally, the multiple monitoring points in the acquisition unit include: at least one monitoring point set on the main line of the power system, and at least one monitoring point set on each branch line.

[0093] Example 3

[0094] According to an embodiment of the present invention, an electronic device is also provided, comprising: a memory storing an executable program; and a processor for running the program, wherein the program executes the power system fault detection method in Embodiment 1 during runtime.

[0095] Example 4

[0096] Embodiments of this application also provide a computer-readable storage medium, which includes a stored executable program, wherein, when the executable program is running, it controls the device where the computer-readable storage medium is located to execute the power system fault detection method of various embodiments of the present invention.

[0097] Example 5

[0098] Embodiments of this application also provide a computer program product, including a computer program that, when executed by a processor, implements the power system fault detection method in various embodiments of the present invention.

[0099] Example 6

[0100] Embodiments of this application also provide a computer program product, including a non-volatile computer-readable storage medium for storing a computer program, which, when executed by a processor, implements the power system fault detection method in various embodiments of the present invention.

[0101] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0102] In the above embodiments of the present invention, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0103] In the several embodiments provided in this application, it should be understood that the disclosed technical content can be implemented in other ways. The device embodiments described above are merely illustrative; for example, the division of units can be a logical functional division, and in actual implementation, there may be other division methods. For instance, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the displayed or discussed mutual coupling, direct coupling, or communication connection may be through some interfaces; the indirect coupling or communication connection between units or modules may be electrical or other forms.

[0104] 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 units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0105] Furthermore, 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. The integrated unit can be implemented in hardware or as a software functional unit.

[0106] If the integrated unit 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 the present invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. 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 described in the various embodiments of the present invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0107] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A fault detection method for a power system, characterized in that, include: In response to a power system fault, a preset resistor is connected to the power system, and the bus zero-sequence voltage of the power system and multiple zero-sequence currents at multiple monitoring points in the power system are obtained, wherein the preset resistor is connected in parallel with the neutral point of the power system; The plurality of zero-sequence currents are projected onto the zero-sequence voltage of the bus to obtain the steady-state projection of the plurality of zero-sequence currents; Based on the steady-state projection of multiple zero-sequence currents, the correlation coefficient between zero-sequence currents at any two adjacent monitoring points is determined. The correlation coefficient between zero-sequence currents at any two adjacent monitoring points is used to characterize the degree of correlation between zero-sequence currents at any two adjacent monitoring points. The degree of correlation includes one of the following: the zero-sequence currents at two adjacent monitoring points are positively correlated, the zero-sequence currents at two adjacent monitoring points are negatively correlated, and the zero-sequence currents at two adjacent monitoring points are uncorrelated. Based on the location of the multiple monitoring points and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points, fault sections are determined from multiple sections of the power system, wherein the multiple sections are obtained by dividing the power system lines through the multiple monitoring points; The method of determining a fault section from multiple sections of the power system based on the location of the plurality of monitoring points and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points includes: determining the line type of the power system, wherein the line type is used to represent the type of line in the power system determined in one of the following ways: according to whether there are branch lines, according to voltage level, and according to line carrying current; and determining the fault section from multiple sections of the power system based on the line type, the location of the plurality of monitoring points, and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points.

2. The method according to claim 1, characterized in that, Projecting the plurality of zero-sequence currents onto the zero-sequence voltage of the bus, respectively, yields the steady-state projection quantities of the plurality of zero-sequence currents, including: For any one of the plurality of zero-sequence currents, the bus zero-sequence voltage is converted into a voltage vector, and the zero-sequence current is converted into a current vector; Determine the vector angle between the voltage vector and the current vector; The steady-state projection of the zero-sequence current is determined based on the voltage vector, the current vector, and the angle between the vectors.

3. The method according to claim 1, characterized in that, Based on the line type, the locations of the multiple monitoring points, and the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points, fault sections are determined from multiple sections of the power system, including: In the case of a branchless line, two target monitoring points are determined from the plurality of monitoring points based on the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points, wherein the two target monitoring points are adjacent monitoring points and the correlation coefficient between the zero-sequence currents at the two target monitoring points is negative. The section between the two target monitoring points is identified as the fault section.

4. The method according to claim 3, characterized in that, In response to the fact that the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points is positive, the method further includes: The last segment along the current direction from the plurality of segments is determined as the fault segment.

5. The method according to claim 1, characterized in that, Based on the line type, the locations of the multiple monitoring points, and the correlation coefficient between the zero-sequence currents at any two adjacent monitoring points, fault sections are determined from multiple sections of the power system, including: In the case where the line type has branch lines, a first monitoring point and a second monitoring point are determined from the plurality of monitoring points, wherein the first monitoring point is located on the main line of the power system and is adjacent to the monitoring points on the plurality of branch lines, and the second monitoring point is located on any one of the branch lines and is adjacent to the first monitoring point. In response to the fact that the correlation coefficients between the zero-sequence currents at the first monitoring point and the second monitoring point are both negative, and the absolute values ​​of the correlation coefficients between the zero-sequence currents at the first monitoring point and the second monitoring point are within a preset range, the segment between the first monitoring point and the second monitoring point is determined as the fault segment.

6. The method according to claim 1, characterized in that, Acquiring multiple zero-sequence currents at multiple monitoring points in the power system, including: The multiple zero-sequence currents are collected by phasor measurement units installed at the multiple monitoring points.

7. The method according to claim 1, characterized in that, In the case where the power system includes multiple branch lines, the multiple monitoring points include: at least one monitoring point located on the main line of the power system, and at least one monitoring point located on each branch line.

8. A fault detection device for a power system, characterized in that, include: The acquisition module is used to connect a preset resistor to the power system in response to the detection of a fault signal, and acquire the bus zero-sequence voltage of the power system and multiple zero-sequence currents at multiple monitoring points in the power system, wherein the preset resistor is connected in parallel with the neutral point of the power system. The projection module is used to project the multiple current vectors corresponding to the multiple zero-sequence currents onto the voltage vector corresponding to the zero-sequence voltage of the bus, so as to obtain the steady-state projection of the multiple zero-sequence currents. The first determining module is used to determine the correlation coefficient between zero-sequence currents at any two adjacent monitoring points based on the steady-state projection of multiple zero-sequence currents. The correlation coefficient between zero-sequence currents at any two adjacent monitoring points is used to characterize the degree of correlation between zero-sequence currents at any two adjacent monitoring points. The degree of correlation includes one of the following: the zero-sequence currents at two adjacent monitoring points are positively correlated, the zero-sequence currents at two adjacent monitoring points are negatively correlated, and the zero-sequence currents at two adjacent monitoring points are uncorrelated. The second determining module is used to determine the fault section from multiple sections of the power system based on the location of the multiple monitoring points and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points, wherein the multiple sections are obtained by dividing the power system lines through the multiple monitoring points; The method of determining a fault section from multiple sections of the power system based on the location of the plurality of monitoring points and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points includes: determining the line type of the power system, wherein the line type is used to represent the type of line in the power system determined in one of the following ways: according to whether there are branch lines, according to voltage level, and according to line carrying current; and determining the fault section from multiple sections of the power system based on the line type, the location of the plurality of monitoring points, and the correlation coefficient between the zero-sequence currents on any two adjacent monitoring points.

9. An electronic device, characterized in that, include: Memory, which stores executable programs; A processor for running the program, wherein the program executes the fault detection method for a power system according to any one of claims 1 to 7.

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