A power distribution line multi-pseudo fault point checking method based on multi-frequency signals

Abstract

The application provides a power distribution line multi-pseudo fault point checking method based on a multi-frequency signal, the checking method comprises a single-ended traveling wave positioning method, a traveling wave positioning terminal for traveling wave positioning is installed at a first end of a line feeder of a transformer substation, current signals collected by power distribution terminals at power distribution lines are collected, and pseudo fault points are excluded according to current frequency information of the current signals and position information of the traveling wave positioning, so that a real fault point is determined; the power distribution terminal comprises a pole-mounted switch and a fault indicator; the application has high economy, can accurately identify the real fault position from multiple pseudo fault points, and can solve the problems of serious pseudo point interference and difficult discrimination of the real fault point in the single-ended method.

Description

Technical Field

[0001] This invention relates to the field of power grid operation and maintenance technology, and in particular to a method for verifying multiple pseudo-fault points in distribution lines based on multi-frequency signals. Background Technology

[0002] As a key link connecting the main grid and end users, the distribution network is characterized by its complex structure, numerous branches, wide line coverage, and variable operating environment, which significantly increases the difficulty of fault location. When a fault occurs, quickly and accurately identifying the fault location is crucial to shortening the power outage time and improving the reliability of power supply.

[0003] Currently, widely used single-ended fault location techniques (such as impedance methods and traveling wave methods) have advantages such as low cost and ease of implementation because they only require the deployment of measuring devices at the beginning of the line, and are therefore widely adopted in engineering practice. However, in multi-branch power grids, branch nodes can cause traveling wave reflection, refraction, or impedance abrupt changes, making it difficult for single-ended methods to effectively distinguish between real fault points and pseudo-fault characteristics caused by branch structures. Similar fault response signals are often generated at multiple branches, thus forming multiple candidate pseudo-fault points. Existing technologies usually rely on empirical thresholds, waveform similarity, or simple logical judgments for screening, which severely limits their discrimination ability and easily leads to misjudgment or missed judgment.

[0004] Therefore, current distribution network fault location technologies generally suffer from several drawbacks when dealing with multi-branch structures, such as severe interference from pseudo-points in single-end methods, difficulty in identifying real fault points, incomplete coverage in dual-end methods, and reliance on strong assumptions in intelligent methods. There is still a lack of a universal solution that can be compatible with existing infrastructure and efficiently and accurately identify the real fault location from multiple pseudo-fault points. Summary of the Invention

[0005] This invention proposes a method for verifying multiple pseudo-fault points in power distribution lines based on multi-frequency signals. It is highly economical, can efficiently and accurately identify the real fault location from multiple pseudo-fault points, and can solve the problems of severe pseudo-point interference and difficulty in identifying real fault points in single-ended methods.

[0006] The present invention adopts the following technical solution.

[0007] A method for verifying multiple pseudo-fault points in distribution lines based on multi-frequency signals is disclosed. The verification method uses a single-end traveling wave localization method. First, a traveling wave localization terminal for traveling wave localization is installed at the beginning of the feeder of the substation line. At the same time, the current signal collected by the distribution terminal at the distribution line is collected. Then, the false fault points are eliminated based on the current frequency information of the current signal and the location information of the traveling wave localization to determine the real fault point. The distribution terminal includes a pole-mounted switch and a fault indicator.

[0008] The method includes the following steps;

[0009] Step S1: When a ground fault occurs, acquire the traveling wave information collected by the traveling wave positioning terminal at the beginning of the substation line feeder;

[0010] Step S2: Obtain the frequency of the transient zero-sequence current signal collected by the power distribution terminal on the line. ; i represents the number of multiple terminals on the line.

[0011] Step S3: Based on the frequency of the transient zero-sequence current signal collected by the distribution terminal on the line. Determine whether it is less than the transient frequency threshold. If the value is less than 0, it is determined to be a ground fault on this line, and step S4 is executed; otherwise, step S9 is executed.

[0012] The corresponding formula is: ;

[0013] Step S4: The traveling wave information collected by the traveling wave positioning terminal at the beginning of the substation line feeder is used to perform single-end traveling wave positioning and give the fault distance;

[0014] Step S5: Based on the line diagram model relationship (distribution network topology information) and the fault distance, provide information on multiple fault points;

[0015] Step S6: Combine the information from multiple fault points with the topology information formed by the traveling wave positioning terminal at the head of the feeder to determine the power distribution terminal on the line;

[0016] Step S7: Based on the location information of the distribution terminal on the line and the frequency of the transient zero-sequence current signal corresponding to the location information... Determine the actual fault path;

[0017] Step S8: Determine the actual fault point based on the actual fault path on the line;

[0018] Step S9: Based on the frequency of the transient zero-sequence current signal collected by the distribution terminal on the line... All are greater than the transient frequency threshold. If the fault is not a grounding fault on this line, exit the diagnostic procedure.

[0019] In step S3, the transient frequency threshold The setting range is 1kHz to 3kHz, specifically 2kHz.

[0020] The multiple fault point information given in step S5 includes one real fault point and multiple pseudo fault points.

[0021] like Figure 2 As shown, the power distribution network where the power distribution line is located is a radial power distribution network.

[0022] The traveling wave positioning device is installed at the beginning of the outgoing line of the substation.

[0023] In step S1, when a ground fault occurs, the traveling wave information collected by the traveling wave positioning terminal at node 1 at the beginning of the substation line feeder is obtained, single-end traveling wave positioning is performed, and the fault distance L is given.

[0024] The traveling wave positioning terminal calculates the distance from the fault point to the substation by detecting the propagation time of the fault traveling wave, which is used for high-precision single-end fault location.

[0025] In the aforementioned distribution network, the substation serves as the sole power source for the entire line, providing electrical output. The substation load bears the total load of all downstream distribution areas and lines.

[0026] The high-voltage side voltage level of the distribution network is 10KV, and the low-voltage side voltage is 400V. The false fault point is the location of the false fault in the distribution network due to distance.

[0027] The advantages of this invention are its strong applicability. It solves the problems of severe false point interference and difficulty in identifying real fault points by relying solely on the single-end traveling wave localization method. The judgment method of the embodiments of this application is simple and has high practicality. This method is less affected by external interference, has a high fault tolerance rate, is simple to implement, convenient and effective, and has high engineering application value.

[0028] This invention proposes a method for verifying multiple pseudo-fault points in power distribution lines based on multi-frequency signals. Relying on the single-ended traveling wave location method, a traveling wave location terminal is installed at the beginning of the feeder in the substation line for traveling wave location. It collects current signals from power distribution terminals (pole-mounted switches, fault indicators) on the line. Based on the current frequency information and the location information, pseudo-fault points are eliminated, and the true fault points are determined. This invention solves the problems of severe pseudo-point interference and difficulty in identifying true fault points in the single-ended method. The judgment method proposed in this application is simple and highly practical.

[0029] The verification method proposed in this invention relies on the single-ended traveling wave location method, which is a universal solution that is highly economical and efficient in accurately identifying the real fault location from multiple pseudo-fault points. It has strong applicability and can solve the problems of serious pseudo-point interference and difficulty in identifying real fault points in the single-ended method when dealing with multi-branch structures in current distribution network fault location technology. Attached Figure Description

[0030] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0031] Appendix Figure 1 This is a flowchart illustrating a method for verifying multiple pseudo-fault points in power distribution lines based on multi-frequency signals, as described in an embodiment of the present invention.

[0032] Appendix Figure 2 This is a schematic topology diagram of a method for verifying multiple pseudo-fault points in a power distribution line based on multi-frequency signals, as described in an embodiment of the present invention. Detailed Implementation

[0033] As shown in the figure, a method for verifying multiple pseudo-fault points in power distribution lines based on multi-frequency signals is presented. The verification method uses the single-end traveling wave positioning method. First, a traveling wave positioning terminal for traveling wave positioning is installed at the beginning of the feeder of the substation line. At the same time, the current signal collected by the power distribution terminal at the power distribution line is collected. Then, based on the current frequency information of the current signal and the position information of the traveling wave positioning, pseudo-fault points are eliminated to determine the real fault point. The power distribution terminal includes a pole-mounted switch and a fault indicator.

[0034] The method includes the following steps;

[0035] Step S1: When a ground fault occurs, acquire the traveling wave information collected by the traveling wave positioning terminal at the beginning of the substation line feeder;

[0036] Step S2: Obtain the frequency of the transient zero-sequence current signal collected by the power distribution terminal on the line. ; i represents the number of multiple terminals on the line.

[0037] Step S3: Based on the frequency of the transient zero-sequence current signal collected by the distribution terminal on the line. Determine whether it is less than the transient frequency threshold. If the value is less than 0, it is determined to be a ground fault on this line, and step S4 is executed; otherwise, step S9 is executed.

[0038] The corresponding formula is: ;

[0039] Step S4: The traveling wave information collected by the traveling wave positioning terminal at the beginning of the substation line feeder is used to perform single-end traveling wave positioning and give the fault distance;

[0040] Step S5: Based on the line diagram model relationship (distribution network topology information) and the fault distance, provide information on multiple fault points;

[0041] Step S6: Combine the information from multiple fault points with the topology information formed by the traveling wave positioning terminal at the head of the feeder to determine the power distribution terminal on the line;

[0042] Step S7: Based on the location information of the distribution terminal on the line and the frequency of the transient zero-sequence current signal corresponding to the location information... Determine the actual fault path;

[0043] Step S8: Determine the actual fault point based on the actual fault path on the line;

[0044] Step S9: Based on the frequency of the transient zero-sequence current signal collected by the distribution terminal on the line... All are greater than the transient frequency threshold. If the fault is not a grounding fault on this line, exit the diagnostic procedure.

[0045] In step S3, the transient frequency threshold The setting range is 1kHz to 3kHz, specifically 2kHz.

[0046] The multiple fault point information given in step S5 includes one real fault point and multiple pseudo fault points.

[0047] like Figure 2 As shown, the power distribution network where the power distribution line is located is a radial power distribution network.

[0048] The traveling wave positioning device is installed at the beginning of the outgoing line of the substation.

[0049] In step S1, when a ground fault occurs, the traveling wave information collected by the traveling wave positioning terminal at node 1 at the beginning of the substation line feeder is obtained, single-end traveling wave positioning is performed, and the fault distance L is given.

[0050] The traveling wave positioning terminal calculates the distance from the fault point to the substation by detecting the propagation time of the fault traveling wave, which is used for high-precision single-end fault location.

[0051] In the aforementioned distribution network, the substation serves as the sole power source for the entire line, providing electrical output. The substation load bears the total load of all downstream distribution areas and lines.

[0052] The high-voltage side voltage level of the distribution network is 10KV, and the low-voltage side voltage is 400V. The false fault point is the location of the false fault in the distribution network due to distance.

[0053] Example:

[0054] by Figure 2 For example, multiple pseudo-faults should be analyzed and explained in conjunction with the distribution network topology and load. Figure 2 It is a radial distribution network. The first end of the substation outgoing line is equipped with a traveling wave positioning device, and the remaining points are equipped with distribution terminals (pole-mounted switches, fault indicators) in the conventional configuration. Figure 2 Nodes 2, 3, 4, 5, and 6 are power distribution terminals (pole-mounted switches, fault indicators). Fault points 1, 2, and 3 are as follows: Figure 2 As indicated by the annotation, there are 4 users in the transformer area, such as Figure 2 The following are shown: Channel 1, Channel 2, Channel 3, and Channel 4;

[0055] The specifications of the terminals used refer to two main categories of equipment: 1. Traveling wave positioning terminals, which have single-ended traveling wave positioning function; 2. Power distribution terminals (pole-mounted switches, fault indicators), where pole-mounted switches and fault indicators are conventional power distribution equipment.

[0056] like Figure 2 As shown, this example uses a typical single-source radial distribution network structure. In this structure, the power source is the substation on the left, extending rightward along the main line from the substation, passing through multiple distribution nodes (nodes 1 to 6), and branching into multiple transformer substations (substation 1 to substation 4). This network uses single-end traveling wave location technology for precise fault location. A traveling wave location device is installed at the beginning of the substation outgoing line, while other key points are configured with distribution terminals in a conventional manner.

[0057] substation

[0058] Location: Located at the far left of the system.

[0059] Function: As the sole power source for the entire line, it provides electrical output.

[0060] Voltage level: Usually 10kV (typical urban / rural power distribution network standard), but can also be set to 35kV depending on the actual system. Here, the default is 10kV medium voltage power distribution system.

[0061] Equipment configuration:

[0062] Traveling wave location device: installed at the beginning of the substation outgoing line (i.e., before node 1), used to capture the traveling wave signal generated by the fault and achieve high-precision single-end fault location.

[0063] Load characteristics: It bears the total load of all downstream transformer areas and lines, depending on the regional electricity demand.

[0064] Node number and device type

[0065]

[0066] Note: The above "pole-mounted switch" usually refers to a load switch or circuit breaker, and "fault indicator" is used to determine the state of short circuit or ground fault.

[0067] Distribution of transformer substations and load information

[0068]

[0069] Note: All distribution areas are powered by 10kV / 0.4kV transformers with step-down voltage. The capacity of each transformer is generally 200kVA~800kVA.

[0070] The load data for the distribution area is estimated based on typical urban distribution networks; the actual values ​​need to be determined in conjunction with specific plans.

[0071] Each distribution area is connected to the low-voltage network through an independent distribution transformer, so they do not affect each other.

[0072] Fault point analysis (colored markers)

[0073] The diagram shows three fault points:

[0074] Fault Point 1: Actual Fault Point

[0075] Location: Between node 4 and area 4.

[0076] Nature: Real fault, single-phase ground fault.

[0077] Location basis: The traveling wave location device can accurately calculate the distance of the point from the substation by detecting the propagation time of the fault traveling wave.

[0078] Fault Point 2: False Fault Point

[0079] Location: Located between node 5 and transformer area 1, near the entrance of transformer area 1.

[0080] Nature: False fault point, that is, not an actual physical fault, but a false fault judgment caused by distance.

[0081] Fault point 3: False fault point

[0082] Location: Located between node 6 and transformer area 3, closer to node 6.

[0083] Nature: False fault point, that is, not an actual physical fault, but a false fault judgment caused by distance.

[0084] Summary of voltage levels and load range

[0085]

[0086] by Figure 2 A schematic topology diagram is used as an example to illustrate a method for verifying multiple pseudo-fault points in a power distribution line based on multi-frequency signals. Figure 2 It is a radial distribution network. The first end of the substation outgoing line is equipped with a traveling wave positioning device, and the remaining points are equipped with distribution terminals (pole-mounted switches, fault indicators) in the conventional configuration. Figure 2 Nodes 2, 3, 4, 5, and 6 are power distribution terminals (pole-mounted switches, fault indicators). Fault points 1, 2, and 3 are as follows: Figure 2 As shown;

[0087] When a ground fault occurs, the traveling wave information collected by the traveling wave positioning terminal at node 1 at the beginning of the substation line feeder is obtained, single-end traveling wave positioning is performed, and the fault distance L is given.

[0088] According to the route Figure 2 Based on the relationship between the diagram and the fault distance, if the distance L between fault point 1, fault point 2, and fault point 3 and the equipment is given, then multiple fault point information (including one real fault point and multiple pseudo-fault points) will be provided; fault point 1, fault point 2, and fault point 3 are as follows: Figure 2 As shown;

[0089] Acquire the frequency of the transient zero-sequence current signal collected by the distribution terminals (pole-mounted switches, fault indicators) at nodes 2, 3, 4, 5, and 6 on the line. ( , , , , )

[0090] The frequency of the transient zero-sequence current signal collected by the power distribution terminal (pole-mounted switch, fault indicator) on the line. ( , , , , From fault points 1, 2, and 3, it can be seen that the fault path from each fault point to the substation must pass through nodes 2 and 3. , Determine if it is less than the transient frequency threshold. If the value is less than 1, it indicates a grounding fault on this line.

[0091]

[0092] Transient frequency threshold It can be set from 1kHz to 3kHz, specifically 2kHz.

[0093] By combining the information from multiple fault points (fault point 1, fault point 2, fault point 3) with the topology information formed by the traveling wave positioning terminal at the beginning of the feeder, the distribution terminal on the line is determined. Figure 2 Power distribution terminals at nodes 2, 3, 4, 5, and 6;

[0094] Fault point 1 - Substation path (node ​​2, node 3, node 4); Fault point 2 - Substation path (node ​​2, node 3, node 5); Fault point 3 - Substation path (node ​​2, node 3, node 6).

[0095] Based on the location information of the power distribution terminal on the line and the frequency of the transient zero-sequence current signal corresponding to the location information... Determine the actual fault path; the frequency of the transient zero-sequence current signal along the fault point 1-substation path (nodes 2, 3, and 4). Less than the transient frequency threshold Therefore, the path from fault point 1 to the substation (nodes 2, 3, and 4) is the actual fault path.

[0096] If the path from fault point 1 to the substation (node ​​2, node 3, node 4) is the actual fault path, then fault point 1 is determined to be the actual fault point.

[0097] The frequency of the transient zero-sequence current signal at fault point 2 - substation path (node ​​2, node 3, node 5) ( , , (Not all are less than the transient frequency threshold) If the path from fault point 2 to the substation (node ​​2, node 3, node 5) is not a fault path, then fault point 2 is determined to be a false fault point.

[0098] The frequency of the transient zero-sequence current signal at fault point 3 - substation path (node ​​2, node 3, node 6) ( , , (Not all are less than the transient frequency threshold) If the path from fault point 2 to the substation (node ​​2, node 3, node 6) is not a fault path, then fault point 2 is determined to be a pseudo-fault point.

Claims

1. A method for verifying multiple pseudo-fault points in power distribution lines based on multi-frequency signals, characterized in that: The verification method includes the single-end traveling wave positioning method. First, a traveling wave positioning terminal for traveling wave positioning is installed at the beginning of the feeder of the substation line. At the same time, the current signal collected by the distribution terminal at the distribution line is collected. Then, the false fault points are eliminated based on the current frequency information of the current signal and the position information of the traveling wave positioning to determine the real fault point. The distribution terminal includes a pole-mounted switch and a fault indicator.

2. The method for verifying multiple pseudo-fault points in distribution lines based on multi-frequency signals according to claim 1, characterized in that: The method includes the following steps; Step S1: When a ground fault occurs, acquire the traveling wave information collected by the traveling wave positioning terminal at the beginning of the substation line feeder; Step S2: Obtain the frequency of the transient zero-sequence current signal collected by the power distribution terminal on the line. ; i represents the number of multiple terminals on the line. Step S3: Based on the frequency of the transient zero-sequence current signal collected by the distribution terminal on the line. Determine whether it is less than the transient frequency threshold. If the value is less than 0, it is determined to be a ground fault on this line, and step S4 is executed; otherwise, step S9 is executed. The corresponding formula is: ; Step S4: The traveling wave information collected by the traveling wave positioning terminal at the beginning of the substation line feeder is used to perform single-end traveling wave positioning and give the fault distance; Step S5: Based on the relationship between the circuit diagram and the fault distance, provide information on multiple fault points; Step S6: Combine the information from multiple fault points with the topology information formed by the traveling wave positioning terminal at the head of the feeder to determine the power distribution terminal on the line; Step S7: Based on the location information of the distribution terminal on the line and the frequency of the transient zero-sequence current signal corresponding to the location information... Determine the actual fault path; Step S8: Determine the actual fault point based on the actual fault path on the line; Step S9: Based on the frequency of the transient zero-sequence current signal collected by the distribution terminal on the line... All are greater than the transient frequency threshold. If the fault is not a grounding fault on this line, exit the diagnostic procedure.

3. The method for verifying multiple pseudo-fault points in distribution lines based on multi-frequency signals according to claim 2, characterized in that: In step S3, the transient frequency threshold The setting range is 1kHz to 3kHz.

4. The method for verifying multiple pseudo-fault points in distribution lines based on multi-frequency signals according to claim 3, characterized in that: The multiple fault point information given in step S5 includes one real fault point and multiple pseudo fault points.

5. The method for verifying multiple pseudo-fault points in distribution lines based on multi-frequency signals according to claim 4, characterized in that: The power distribution network where the power distribution line is located is a radial power distribution network.

6. The method for verifying multiple pseudo-fault points in distribution lines based on multi-frequency signals according to claim 5, characterized in that: The traveling wave positioning device is installed at the beginning of the outgoing line of the substation.

7. The method for verifying multiple pseudo-fault points in distribution lines based on multi-frequency signals according to claim 6, characterized in that: In step S1, when a ground fault occurs, the traveling wave information collected by the traveling wave positioning terminal at the beginning of the substation line feeder is obtained, single-end traveling wave positioning is performed, and the fault distance L is given.

8. The method for verifying multiple pseudo-fault points in power distribution lines based on multi-frequency signals according to claim 7, characterized in that: The traveling wave positioning terminal calculates the distance from the fault point to the substation by detecting the propagation time of the fault traveling wave, which is used for high-precision single-end fault location.

9. The method for verifying multiple pseudo-fault points in distribution lines based on multi-frequency signals according to claim 7, characterized in that: In the aforementioned distribution network, the substation serves as the sole power source for the entire line, providing electrical output. The substation load bears the total load of all downstream distribution areas and lines.

10. The method for verifying multiple pseudo-fault points in distribution lines based on multi-frequency signals according to claim 7, characterized in that: The high-voltage side voltage level of the distribution network is 10KV, and the low-voltage side voltage is 400V. The false fault point is the location of the false fault in the distribution network due to distance.

Images