Line fault positioning method and system applied to 10kV power distribution network

Abstract

The invention discloses a line fault positioning method and system applied to a 10kV power distribution network, and relates to the technical field of power grid line fault positioning. According to the line fault positioning method applied to the 10kV power distribution network, basic parameters of a line of the 10kV power distribution network are determined, the basic parameters are corrected, corrected line parameters are determined, the corrected line parameters comprise a high-voltage side bus equivalent impedance correction value and a line unit length impedance correction value, and after the fault type is determined, the line fault positioning method is applied to the 10kV power distribution network. Determining target impedance between the bus and the fault point based on the high-voltage side bus equivalent impedance correction value and the main transformer short-circuit impedance; the distance interval of the fault point is determined based on the target impedance between the bus and the fault point and the corrected value of the impedance value per unit length of the line, the fault point is determined in the distance interval of the fault point through unmanned aerial vehicle routing inspection, and the problem of inaccurate fault positioning caused by line parameter errors in different operation modes is solved.

Description

Technical Field

[0001] The present invention relates to the technical field of power grid line fault location, and in particular to a method and system for locating a 10kV power distribution network line fault. Background Art

[0002] At present, in my country's distribution network, with the decline in cable application costs and the development of urban and rural network transformation, power cables are increasingly used in distribution systems, and a line mode mixed with overhead lines and cables has emerged; since the distribution network is directly connected to users, especially in rural distribution networks, each end of each line is only connected to a step-down transformer, and generally only the power supply end substation has the conditions for measurement and calculation; single-phase grounding fault in the distribution network is the main fault of the distribution network, accounting for 70%-80% of the total line faults, which has an important impact on the safe and reliable operation of the distribution network. Most of the traditional distance measurement algorithms are carried out for this type of fault; the distribution line is short, and the requirements for fault distance measurement accuracy are high.

[0003] A Chinese patent application with publication number CN117538676A discloses a method for locating a fault in a 10kV distribution network line, including constructing a database of basic data of the distribution network line; calculating the main transformer short-circuit impedance of the faulty substation according to the main transformer short-circuit impedance voltage of the faulty substation and the main transformer capacity of the faulty substation; determining the operation mode of the faulty substation; determining the corresponding main transformer short-circuit impedance according to the operation mode of the faulty substation; obtaining the fault type of the faulty substation, and determining the target impedance between the busbar where the protection device is installed and the fault point, the protection device being installed on the 10kV distribution network line; and determining the location of the fault point according to the target impedance, the impedance value per unit length corresponding to the line model, and the main transformer short-circuit impedance of the faulty substation.

[0004] However, in the actual positioning process, the equivalent impedance and unit length impedance of the high-voltage side bus will change with the environment and the length of time the system is in operation, which will cause positioning errors when calculating the distance interval to the fault point, reducing the accuracy and reliability of fault positioning. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a method and system for locating line faults in a 10kV distribution network, which solves the problem of inaccurate fault locating caused by line parameter errors in different operating modes.

[0006] To achieve the above purpose, the present invention is implemented through the following technical scheme: a method for locating faults in a 10kV distribution network line, comprising the following steps: determining basic parameters of a 10kV distribution network line, the basic parameters including a high-voltage side busbar parameterized equivalent impedance and a line unit length parameterized impedance value, wherein the high-voltage side busbar parameterized equivalent impedance includes a parameterized equivalent impedance under a large operating mode and a parameterized equivalent impedance under a small operating mode; correcting the basic parameters to determine corrected line parameters, the corrected line parameters including a high-voltage side busbar equivalent impedance correction value and a line unit length impedance correction value The high-voltage side bus equivalent impedance correction value includes an equivalent impedance correction value under a large operation mode and an equivalent impedance correction value under a small operation mode; after determining the fault type, the target impedance between the bus and the fault point is determined based on the high-voltage side bus equivalent impedance correction value and the main transformer short-circuit impedance, the fault type includes a two-phase short circuit and a three-phase short circuit, and the target impedance includes a target impedance under a large operation mode and a target impedance under a small operation mode; the fault point distance interval is determined based on the target impedance between the bus and the fault point and the line unit length impedance correction value, and the fault point is determined within the fault point distance interval through drone inspection.

[0007] Furthermore, the determination of the basic parameters of the 10kV distribution network line includes the following steps: obtaining the system topology structure under the large operation mode from the dispatching platform, and determining the parameter equivalent impedance under the large operation mode from the 10kV distribution network line basic parameter database based on the system topology structure under the large operation mode; obtaining the system use part topology structure under the small operation mode from the dispatching platform, and determining the parameter equivalent impedance under the small operation mode from the 10kV distribution network line basic parameter database based on the system use part topology structure under the small operation mode; obtaining the line unit length parameter impedance value from the 10kV distribution network line basic parameter database based on the line model.

[0008] Furthermore, the method for determining the corrected line parameters is as follows: determine basic parameter correction data, the basic parameter correction data including an equivalent impedance correction coefficient in a large operating mode, an equivalent impedance correction coefficient in a small operating mode and a line unit length impedance correction coefficient; and correct the basic parameters based on the basic parameter correction data.

[0009] Furthermore, the method for obtaining the equivalent impedance correction value in the large operation mode, the equivalent impedance correction value in the small operation mode and the line unit length impedance correction value is as follows:

[0010]

[0011] Among them, ZC d To determine the equivalent impedance in the large operation mode, ZC x To set the equivalent impedance in the small operation mode, ZC LThe impedance per unit length of the line is determined by ZD d is the equivalent impedance correction value in the large operation mode, ZD x is the equivalent impedance correction value in the small operation mode, ZD L is the correction value of line impedance per unit length, xZ d is the equivalent impedance correction factor in the large operating mode, xZ x is the equivalent impedance correction factor in the small operation mode, xZ L It is the correction factor of line impedance per unit length.

[0012] Furthermore, a method for determining the equivalent impedance correction coefficient in the large operation mode is as follows: obtaining basic operation parameters of a 10kV distribution network system, the basic operation parameters including the system commissioning time, the system ambient temperature change curve, and the system ambient humidity change curve; obtaining large operation characteristic parameters when the 10kV distribution network is operating in the large operation mode, the large operation characteristic parameters including the load fluctuation rate and the load equipment temperature change curve; obtaining a large operation mode equivalent impedance correction coefficient comparison data set corresponding to the system commissioning time from a 10kV distribution network line basic parameter database based on the system commissioning time, the large operation mode equivalent impedance correction coefficient comparison data set including a number of large operation mode correction coefficient matching data, the large operation mode correction coefficient matching data including the system ambient temperature change matching curve, the system ambient humidity change matching curve, the large operation mode system load average fluctuation rate, and the large operation mode load equipment average temperature change curve; determining the most matching large operation mode correction coefficient matching data, and obtaining the large operation mode equivalent impedance correction coefficient corresponding to the large operation mode correction coefficient matching data from the 10kV distribution network line basic parameter database.

[0013] Furthermore, a method for determining the equivalent impedance correction coefficient in the small operation mode is as follows: obtaining basic operation parameters of a 10kV distribution network system, the basic operation parameters including the system commissioning time, the system ambient temperature change curve, and the system ambient humidity change curve; obtaining small operation characteristic parameters when the 10kV distribution network is operating in the small operation mode, the small operation characteristic parameters including the system use part of the topology structure and the system frequency stability; obtaining a small operation mode equivalent impedance correction coefficient comparison data set corresponding to the system commissioning time from a 10kV distribution network line basic parameter database based on the system commissioning time, the small operation mode equivalent impedance correction coefficient comparison data set including a number of small operation mode correction coefficient matching data, the small operation mode correction coefficient matching data including the system ambient temperature change matching curve, the system ambient humidity change matching curve, the small operation mode system use part of the topology structure and the small operation mode system frequency stability; determining the most matching small operation mode correction coefficient matching data, and obtaining the small operation mode equivalent impedance correction coefficient corresponding to the small operation mode correction coefficient matching data from the 10kV distribution network line basic parameter database.

[0014] Furthermore, a method for determining a correction coefficient of line impedance per unit length is as follows: obtaining line environment change data, the line environment change data including a system environment temperature change curve, a system environment humidity change curve, a line environment wind force change curve, and a line environment light radiation intensity change curve; obtaining system commissioning time, and based on the system commissioning time, obtaining a line environment change matching data set corresponding to the system commissioning time from a 10kV distribution network line basic parameter database, the line environment change matching data set including a number of line environment change matching data, the line environment change matching data including a system environment temperature change matching curve, a system environment humidity change matching curve, a line environment wind force change matching curve, and a line environment light radiation intensity change matching curve; determining the most matching line environment change matching data based on a sliding window comparison, and obtaining a line unit length impedance correction coefficient corresponding to the line environment change matching data from the 10kV distribution network line basic parameter database.

[0015] Furthermore, when the fault type is a two-phase short circuit, the method for obtaining the target impedance is:

[0016]

[0017] When the fault type is three-phase short circuit, the method for obtaining the target impedance is:

[0018]

[0019] Among them, V eis the rated voltage of the 10kV distribution network line, I f2 is the two-phase short-circuit current, I f3 is the three-phase short-circuit current, ZD d To determine the equivalent impedance in the large operation mode, ZD x is the equivalent impedance parameterized in the small operation mode, Z z is the short-circuit impedance of the main transformer, N is the CT ratio of the 10kV distribution network line, Zm d is the target impedance in the large operation mode, Zm x is the target impedance in the small operation mode, and θ is the phase angle.

[0020] Furthermore, the fault point distance interval is [L x , L d ],in:

[0021]

[0022] Where, L x is the minimum distance, L d is the maximum distance.

[0023] A fault location system for a 10kV distribution network line, comprising a basic parameter acquisition module, a basic parameter correction module, a target impedance determination module and a fault point determination module, wherein: the basic parameter acquisition module is used to determine the basic parameters of the 10kV distribution network line, the basic parameters include the high-voltage side busbar parameterized equivalent impedance and the line unit length parameterized impedance value, wherein the high-voltage side busbar parameterized equivalent impedance includes the parameterized equivalent impedance under a large operating mode and the parameterized equivalent impedance under a small operating mode; the basic parameter correction module is used to correct the basic parameters and determine the corrected line parameters, the corrected line parameters include the high-voltage side busbar The equivalent impedance correction value and the line unit length impedance correction value, the high-voltage side bus equivalent impedance correction value includes the equivalent impedance correction value under the large operation mode and the equivalent impedance correction value under the small operation mode; the target impedance determination module is used to determine the target impedance between the bus and the fault point based on the high-voltage side bus equivalent impedance correction value and the main transformer short-circuit impedance after determining the fault type, and the fault types include two-phase short circuit and three-phase short circuit; the fault point determination module is used to determine the fault point distance interval based on the target impedance between the bus and the fault point and the line unit length impedance correction value, and determine the fault point through drone inspection within the fault point distance interval.

[0024] The present invention has the following beneficial effects:

[0025] (1) This method for locating line faults in a 10 kV distribution network uses key factors such as ambient temperature and humidity, wind speed, light radiation intensity, load fluctuation rate, frequency stability, and topological structure to ensure that the impedance correction coefficient can accurately match the actual operating status of the current line. The dynamic fusion of the similarity of various factors makes the final selected correction coefficient more accurate, thereby significantly improving the accuracy of fault location and reducing the error range.

[0026] (2) This method for locating line faults in a 10kV distribution network can adapt to various operating modes by selecting and calculating impedance correction coefficient matching data in different modes (large operating mode, small operating mode). Under different load, topology and frequency conditions, the system can dynamically select the optimal matching correction coefficient, so that the correction process can adapt to the specific needs of both large and small loads, thereby enhancing the adaptability of the system.

[0027] Of course, any product implementing the present invention does not necessarily need to achieve all of the advantages described above at the same time. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The present invention is a flow chart of a method for locating line faults in a 10kV distribution network.

[0029] Figure 2 This is a module structure connection diagram of the present invention applied to a 10kV distribution network line fault location system. DETAILED DESCRIPTION

[0030] The embodiment of the present application is applied to a 10kV distribution network line fault location method and system, and first determines and corrects the basic parameters of the line, especially the equivalent impedance of the high-voltage side bus and the impedance per unit length of the line. The equivalent impedance under different operating modes (large operating mode and small operating mode) is crucial in fault location. Correcting these parameters can be more in line with the actual line conditions and reduce deviations. Then, according to the fault type (such as two-phase short circuit and three-phase short circuit), the corrected equivalent impedance is combined with the main transformer short-circuit impedance to determine the target impedance value between the bus and the fault point. Finally, by calculating the distance interval of the fault point, the fault point can be efficiently determined during the drone inspection.

[0031] See also Figure 1 The embodiment of the present invention provides a technical solution: a method for locating a fault in a 10kV distribution network line, comprising the following steps: determining basic parameters of the 10kV distribution network line, the basic parameters including a high-voltage side busbar parameterized equivalent impedance and a line unit length parameterized impedance value, wherein the high-voltage side busbar parameterized equivalent impedance includes a parameterized equivalent impedance in a large operating mode and a parameterized equivalent impedance in a small operating mode.

[0032] The system topology structure under the large operation mode is obtained from the dispatching platform, and the parameterized equivalent impedance under the large operation mode is determined from the 10kV distribution network line basic parameter database based on the system topology structure under the large operation mode; the system use part topology structure under the small operation mode is obtained from the dispatching platform, and the parameterized equivalent impedance under the small operation mode is determined from the 10kV distribution network line basic parameter database based on the system use part topology structure under the small operation mode; the line unit length parameter impedance value is obtained from the 10kV distribution network line basic parameter database based on the line model.

[0033] By extracting equivalent impedances under large and small operation modes respectively, the deviations that may be caused by using fixed impedance values ​​are avoided, ensuring that the impedance parameters are consistent with the current system status. The impedance parameters obtained according to the actual topology and line type of the system are more accurate, making the subsequent fault point location calculation more accurate and reducing the error range. In addition, the topology information of the dispatching platform is used to dynamically extract impedance parameters, realizing the efficient combination of the dispatching system and the basic parameter database, which is conducive to dynamic adjustment and rapid response. The system topology may change under different load conditions. Dynamically obtaining impedance values ​​can effectively cope with the actual use of the distribution network, so that this embodiment can maintain high-precision fault location in various operation modes.

[0034] The basic parameters are corrected to determine the corrected line parameters. The corrected line parameters include the high-voltage side bus equivalent impedance correction value and the line unit length impedance correction value. The high-voltage side bus equivalent impedance correction value includes the equivalent impedance correction value under the large operating mode and the equivalent impedance correction value under the small operating mode.

[0035] Determine basic parameter correction data, the basic parameter correction data includes an equivalent impedance correction coefficient in a large operation mode, an equivalent impedance correction coefficient in a small operation mode and a line unit length impedance correction coefficient; correct the basic parameters based on the basic parameter correction data.

[0036] The method for obtaining the equivalent impedance correction value in the large operation mode, the equivalent impedance correction value in the small operation mode and the line unit length impedance correction value is as follows:

[0037]

[0038] Among them, ZC d To determine the equivalent impedance in the large operation mode, ZC x To set the equivalent impedance in the small operation mode, ZC L The impedance per unit length of the line is determined by ZD d is the equivalent impedance correction value in the large operation mode, ZD x is the equivalent impedance correction value in the small operation mode, ZD L is the correction value of line impedance per unit length, xZd is the equivalent impedance correction factor in the large operating mode, xZ x is the equivalent impedance correction factor in the small operation mode, xZ L It is the correction factor of line impedance per unit length.

[0039] The impedance value of the system will be different in different operating modes. The correction coefficient is introduced to dynamically adjust the impedance value in different modes to cope with changes in actual operating conditions. This adjustment method can effectively compensate for impedance deviations caused by factors such as system load and environmental changes, and is closer to actual operating conditions. It solves the problem of fault location deviation caused by inaccurate parameters and improves the accuracy of fault location.

[0040] The method for determining the equivalent impedance correction coefficient in the large operation mode is as follows: obtain the basic operation parameters of the 10kV distribution network system, the basic operation parameters include the system commissioning time (the operation record of the 10kV distribution network system since it was put into use, automatically stored by the distribution network dispatching system or database), the system's ambient temperature change curve and the system's ambient humidity change curve (these two curves are obtained by periodic recording of temperature and humidity sensors installed in the distribution network environment); obtain the large operation characteristic parameters of the 10kV distribution network when operating in the large operation mode, the large operation characteristic parameters include load fluctuation rate (calculated according to the real-time load data obtained by the load data acquisition system, using the fluctuation rate calculation formula (usually the ratio of the maximum load fluctuation to the average value)) and the load equipment temperature change curve (obtained from the periodic recording data of the load equipment temperature sensor).

[0041] Based on the system commissioning time, a large operation mode equivalent impedance correction coefficient comparison data set corresponding to the system commissioning time is obtained from the 10kV distribution network line basic parameter database. The large operation mode equivalent impedance correction coefficient comparison data set includes several large operation mode correction coefficient matching data. The large operation mode correction coefficient matching data includes the system ambient temperature change matching curve, the system ambient humidity change matching curve, the large operation mode system load average fluctuation rate and the large operation mode load equipment average temperature change curve.

[0042] The length of time in use directly affects the aging and performance degradation of system components, and the impedance value of components will also increase over time. As an important factor in the correction coefficient, the length of use can effectively reflect the impedance changes caused by aging. Temperature and humidity affect the performance of conductivity and insulation materials, especially in large operating modes. The thermal stress and humidity changes in the system will directly affect the impedance. Therefore, the ambient temperature and humidity curve reflects the impact of the external environment on impedance. Fluctuations in temperature and humidity will cause changes in line impedance. Higher temperature and humidity will accelerate equipment aging and increase system impedance.

[0043] The load fluctuation rate represents the dynamic changes of the system load under the large operation mode, and reflects the operating stability of the system. A large fluctuation rate will cause frequent load fluctuations, which may lead to instantaneous temperature changes and stress concentration, and thus affect the system impedance. Frequent load fluctuations will cause current transients, which will in turn cause thermal stress on cables and equipment, affecting the instantaneous impedance value and correction factor of the system. The load device temperature change curve reflects the heat dissipation of the load device under the large operation mode. The temperature change of the device will directly affect its impedance, which can be used to evaluate the actual impedance change of the device under different load conditions. Temperature changes will affect the impedance characteristics of the conductive components inside the device. The higher the temperature, the greater the impedance is generally, so it is necessary to make corrections based on the temperature change curve of the load device.

[0044] These parameters together constitute the impedance characteristics of the 10kV distribution network line in the large operation mode. The length of time in use provides the aging benchmark of the system, while the changes in ambient temperature and humidity, load fluctuation rate and load equipment temperature reflect the impact of the operating environment and dynamic load on the impedance from the actual operation perspective. Combining these factors, the equivalent impedance correction factor in the large operation mode can be determined more accurately to cope with changes in external conditions and internal states and ensure the accuracy of impedance correction. The dynamic determination of this correction factor improves the system's sensitivity to fault location, allowing the impedance value to be adjusted according to real-time conditions.

[0045] The most matching large operation mode correction coefficient matching data is determined, and the equivalent impedance correction coefficient under the large operation mode corresponding to the large operation mode correction coefficient matching data is obtained from the 10kV distribution network line basic parameter database.

[0046] Calculate the absolute value of the difference between the load fluctuation rate and the average load fluctuation rate of the large operation mode system, which is recorded as the load deviation f p .

[0047] Using the sliding window comparison form, the system's ambient temperature change curve and the system's ambient temperature change matching curve are analyzed section by section, and the difference equation is used to determine the temperature similarity σ between the system's ambient temperature change curve and the system's ambient temperature change matching curve under the large operating mode Dw , for example, the formula of the difference equation is Where σ represents the degree of similarity, i is the number of the sliding window, n is the total number of sliding windows, j is the number of the comparison point in the sliding window, m is the total number of comparison points in each sliding window, and X sij It is used to represent the actual value of the jth comparison point in the i-th sliding window of the change curve, X cijRepresents the matching value of the jth comparison point in the i-th sliding window in the change matching curve. Through the difference equation, the temperature similarity between the system's ambient temperature change curve and the system's ambient temperature change matching curve in the large operation mode can be calculated. Similarly, based on the same calculation method, the humidity similarity between the system's ambient humidity change curve and the system's ambient humidity change matching curve can also be determined. Ds , the device temperature similarity between the load device temperature change curve and the average temperature change curve of the load device in the operation mode σ sw .

[0048] f p , σ Dw , σ Ds and σ sw Perform fusion to determine the comprehensive similarity value under the large operation mode:

[0049]

[0050] Among them, δ a is the comprehensive similarity value under the large operation mode corresponding to the a-th large operation mode correction coefficient matching data, is the load deviation corresponding to the correction coefficient matching data of the ath large operation mode, is the temperature similarity corresponding to the matching data of the correction coefficient of the ath large operating mode, is the humidity similarity corresponding to the correction coefficient matching data of the ath large operation mode, is the equipment temperature similarity corresponding to the matching data of the correction coefficient of the ath large operation mode, and a1 is the temperature similarity set in the basic parameter database of the 10kV distribution network line. The weight factor of a2 is set in the 10kV distribution network line basic parameter database. The weight factor of a3 is set in the 10kV distribution network line basic parameter database. The weight factor of a4 is set in the 10kV distribution network line basic parameter database. The weight factor of .

[0051] By determining the minimum δ a , the most matching large operating mode correction coefficient matching data can be determined.

[0052] Four key factors, load fluctuation, ambient temperature, humidity, and equipment temperature, are considered. Each factor affects the system impedance, and the combination of the four factors can more comprehensively reflect the system status under the actual operating mode. The sliding window difference method is used to compare the change curves of each factor section by section and calculate the degree of similarity. This method can dynamically and locally evaluate the difference between the actual system curve and the database matching curve, which helps to capture instantaneous changes and make the calculation results more accurate. By determining the minimum δ a , you can find the matching data with the highest similarity, indicating that the data is closest to the current operating status. The higher the matching degree, the better the adaptability of the impedance correction coefficient, and the higher the accuracy of the impedance adjustment. The accurately selected correction coefficient can effectively compensate for impedance changes and reduce impedance errors caused by environmental and load changes, thereby improving the accuracy of fault location and reducing errors caused by inaccurate parameters.

[0053] The method for determining the equivalent impedance correction coefficient in the small operation mode is as follows: obtain the basic operation parameters of the 10kV distribution network system, the basic operation parameters include the system commissioning time, the system environment temperature change curve and the system environment humidity change curve; obtain the small operation characteristic parameters of the 10kV distribution network when operating in the small operation mode, the small operation characteristic parameters include the system use part of the topology structure and the system frequency stability; based on the system commissioning time, obtain the small operation mode equivalent impedance correction coefficient comparison data set corresponding to the system commissioning time from the 10kV distribution network line basic parameter database, the small operation mode equivalent impedance correction coefficient comparison data set includes a number of small operation mode correction coefficient matching data, the small operation mode correction coefficient matching data includes the system environment temperature change matching curve, the system environment humidity change matching curve, the small operation mode system use part of the topology structure and the small operation mode system frequency stability; determine the most matching small operation mode correction coefficient matching data, and obtain the small operation mode equivalent impedance correction coefficient corresponding to the small operation mode correction coefficient matching data from the 10kV distribution network line basic parameter database.

[0054] The temperature change curve of the environment in which the system is located affects the resistivity of the conductor, especially in the small operation mode, due to the low load, the impact of ambient temperature on the system impedance is more significant. The temperature change curve can help evaluate the magnitude of the change in impedance caused by temperature in the operation mode. The ambient temperature and the load change, topology, and frequency stability of the system jointly affect the impedance of the grid. Especially when the load is small, the impact of temperature on impedance is more significant. Humidity changes, together with the length of use and temperature changes, reflect the external environment of the system. Especially under low load conditions, humidity changes may further accelerate the aging of the system insulation and have a greater impact on the impedance.

[0055] In the low-load operation mode, the system usually only uses part of the topology, and the configuration of these structures will affect the impedance value. By identifying the topology used, the actual impedance of the system in the low-load operation mode can be judged more accurately. The use of partial topology makes the current distribution and impedance distribution different from that in full-load operation. Combined with parameters such as the length of time in use, temperature and humidity changes, the impedance characteristics in the low-load operation mode can be more accurately reflected. Frequency stability can reflect the stability of the system load. Frequency fluctuations under low load may cause transient impedance changes. By evaluating frequency stability, the dynamic impact on impedance can be identified. Frequency fluctuations will cause instantaneous changes in impedance, especially in the low-load operation mode, where such fluctuations have a more significant impact on the system impedance.

[0056] The use time combined with the changes in ambient temperature and humidity can provide the long-term change trend of impedance. The effects of aging, temperature and humidity on impedance are usually superimposed and increase over time. In the small operation mode, the load is light and the topology is adjusted, and frequency stability becomes a key indicator. Frequency fluctuations are often more significant in this mode, so the topology and frequency fluctuations can work together to evaluate the impact of small loads on impedance. The system usage time, temperature and humidity change curve, topology and frequency fluctuations work together to ensure that the correction factor can reflect the impact of equipment aging, environmental impact and small load characteristics on impedance, and ensure that the correction factor of the system in the small operation mode is close to the actual operation.

[0057] Based on the same sliding window comparison and differential equation as above, the temperature similarity corresponding to the small operation mode correction coefficient matching data and the humidity similarity corresponding to the small operation mode correction coefficient matching data can be determined.

[0058] Use and f p The same calculation method can be used to determine the frequency similarity p between the system frequency stability (by calculating the mean square error of the system frequency) and the frequency stability of the small operation mode system frequency p .

[0059] For the system using partial topology and the small operation mode system using partial topology, the topology similarity can be comprehensively determined using node similarity and edge similarity, where the calculation formulas for topology similarity, node similarity and edge similarity are:

[0060]

[0061] Among them, T b is the topological structure similarity corresponding to the matching data of the b-th small operation mode correction coefficient, T db is the node similarity corresponding to the matching data of the b-th small operation mode correction coefficient, T bb is the edge similarity corresponding to the b-th small operation mode correction coefficient matching data, T is stored in the 10kV distribution network line basic parameter database db The weight factor of T is stored in the 10kV distribution network line basic parameter database bb The weight factor is NA, which is the node set of the partial topology structure used by the system, and NB b The bth small operation mode system uses a set of nodes in the partial topology structure, EA is the set of edges in the partial topology structure used by the system, and EB is b The edge set of the partial topology used for the b-th small operation mode system.

[0062] The similarity of the topological structure is evaluated by the similarity of the sets of nodes and edges, ensuring that the topological configuration of the system in the small operation mode is consistent with the topological structure of the small operation mode matching data in the database. Node similarity reflects the matching degree of functional nodes in the network topology, while edge similarity reflects the similarity of connection relationships. This can more comprehensively measure the similarity of the topological structure and improve the matching accuracy.

[0063] Determine the comprehensive similarity value in the small operation mode:

[0064]

[0065] Among them, δ b is the comprehensive similarity value under the small operation mode corresponding to the b-th small operation mode correction coefficient matching data, is the frequency similarity corresponding to the b-th small operation mode correction coefficient matching data, is the temperature similarity corresponding to the b-th small operation mode correction coefficient matching data, is the humidity similarity corresponding to the b-th small operation mode correction coefficient matching data, b1 is the humidity similarity set in the 10kV distribution network line basic parameter database The weight factor of b2 is set in the 10kV distribution network line basic parameter database. The weight factor of b3 is set in the 10kV distribution network line basic parameter database. b4 is the weight factor of T set in the 10kV distribution network line basic parameter database. b The weight factor of .

[0066] Through a multi-dimensional similarity evaluation method (temperature, humidity, frequency, and topology), the system status in the small operation mode is analyzed from multiple angles to ensure that the selected correction coefficient accurately reflects the impedance characteristics of the system under low load, frequency change, and topology change. In the small operation mode, the load is lighter and the frequency fluctuation is more likely. The introduction of frequency similarity and topology similarity better adapts to the conditions of small load and unstable frequency, which helps the correction coefficient to dynamically fit the actual state. By analyzing the similarity of temperature, humidity, frequency, and topology, the error caused by parameter deviation can be significantly reduced. The higher the matching degree, the better the adaptability of the impedance correction coefficient, thereby improving the accuracy of fault location and reducing the misjudgment rate of fault diagnosis. In addition, this standardized similarity matching process is easy to realize automatically, which can reduce manual intervention, automatically evaluate and select the best correction coefficient when the system is running, and further improve the positioning efficiency and response speed in the small operation mode.

[0067] The method for determining the correction coefficient of the impedance value per unit length of the line is as follows: obtaining the environmental change data of the line, the environmental change data of the line includes the system environmental temperature change curve, the system environmental humidity change curve, the line environmental wind force change curve (data is collected by the wind speed sensor installed near the line) and the line environmental light radiation intensity change curve (radiation intensity data is collected in real time by the light radiation sensor installed around the line); obtaining the system commissioning time, and based on the system commissioning time, obtaining the line environmental change matching data set corresponding to the system commissioning time from the 10kV distribution network line basic parameter database, the line environmental change matching data set includes several line environmental change matching data, and the line environmental change matching data includes the system environmental temperature change matching curve, the system environmental humidity change matching curve, the line environmental wind force change matching curve and the line environmental light radiation intensity change matching curve; determining the most matching line environmental change matching data based on the sliding window comparison, and obtaining the line unit length impedance value correction coefficient corresponding to the line environmental change matching data from the 10kV distribution network line basic parameter database.

[0068] The relationship between temperature and impedance is quite significant. The rise in temperature will increase the resistance of the conductor material and affect the impedance characteristics of the line. At the same time, there is a synergistic effect between temperature and factors such as humidity and light radiation, which have a compound effect on resistance and insulation performance. Humidity affects the electrical insulation of the line. Especially in a high humidity environment, the decline in insulation performance around the conductor may cause impedance changes. The synergistic effect of humidity, temperature and wind can produce more complex impedance change effects. Wind forms an interactive relationship with temperature by affecting the heat dissipation speed of the line. Especially in high wind speed conditions, it can significantly reduce the line temperature, thereby reducing the impedance increment caused by temperature. In addition, under the influence of wind, the line will shake, causing mechanical loss of the line and affecting the impedance of the line. Light radiation is closely related to temperature. Increased light radiation will increase the surface temperature of the line and affect the impedance, especially under long-term exposure, which has a significant impact on resistance and insulation. In addition, light radiation and wind work together to adjust the change of line temperature.

[0069] Temperature, humidity, wind, and light radiation are not isolated factors that affect line impedance, but are interrelated. For example, rising temperature will increase impedance, but if the wind is stronger and the heat dissipation effect is enhanced, it will offset some of the temperature effects. The combined effect of humidity and temperature may further accelerate the degradation of insulation performance. Environmental conditions at different times and places may vary greatly. By combining these external environmental parameters, the impedance correction factor can be dynamically adjusted to make it more suitable for the current environmental conditions. Through the comprehensive analysis of multi-dimensional environmental parameters, the impedance correction factor per unit length of the line can more accurately reflect the current external environmental conditions, thereby ensuring the accuracy of the impedance correction.

[0070] Based on the same sliding window comparison and differential equation as above, the line temperature similarity ρ between the system ambient temperature change curve and the system ambient temperature change matching curve is determined w , the line humidity similarity ρ between the system environment humidity change curve and the system environment humidity change matching curve s , the line wind force similarity ρ between the line environment wind force change curve and the line environment wind force change matching curve f The line light radiation intensity similarity ρ between the line environment light radiation intensity change curve and the line environment light radiation intensity change matching curve g .

[0071] Calculate the comprehensive similarity of the line environment:

[0072]

[0073] In the formula, δ c is the comprehensive similarity of the line environment corresponding to the environmental change matching data of the cth line, is the line temperature similarity corresponding to the environmental change matching data of the cth line, is the line humidity similarity corresponding to the environmental change matching data of the cth line, is the wind force similarity of the cth line corresponding to the environmental change matching data, is the line optical radiation intensity similarity corresponding to the environmental change matching data of the cth line, and c1 is the value set in the 10kV distribution network line basic parameter database. The weight factor of c1 is set in the 10kV distribution network line basic parameter database. The weight factor of c2 is set in the 10kV distribution network line basic parameter database. The weight factor of c 3 is set in the 10kV distribution network line basic parameter database The weight factor of c4 is set in the 10kV distribution network line basic parameter database. The weight factor of .

[0074] By comparing the change curves of each environmental factor (temperature, humidity, wind speed, light radiation) section by section through the sliding window, the matching data can be automatically screened by calculating the comprehensive similarity, reducing the necessity of human intervention, capturing the fluctuation characteristics in the short term, and making a detailed comparison with the matching data. The difference equation calculates the difference between the actual change value and the matching value in each window to obtain the similarity. This method ensures that the similarity calculation is not only based on the overall trend, but also reflects local and short-term fluctuations, making the similarity evaluation more accurate.

[0075] After determining the fault type, the target impedance between the bus and the fault point is determined based on the equivalent impedance correction value of the high-voltage side bus and the short-circuit impedance of the main transformer. The fault types include two-phase short circuit and three-phase short circuit. The target impedance includes the target impedance under the large operation mode and the target impedance under the small operation mode.

[0076] When the fault type is two-phase short circuit, the method for obtaining the target impedance is:

[0077]

[0078] When the fault type is three-phase short circuit, the method for obtaining the target impedance is:

[0079]

[0080] Among them, V e is the rated voltage of the 10kV distribution network line, I f2 is the two-phase short-circuit current, I f3 is the three-phase short-circuit current, Z z is the short-circuit impedance of the main transformer, N is the CT ratio of the 10kV distribution network line, Zm dis the target impedance in the large operation mode, Zm x is the target impedance in the small operation mode, and θ is the phase angle.

[0081] The distance interval of the fault point is determined based on the target impedance between the busbar and the fault point and the correction value of the impedance per unit length of the line, and the fault point is determined by drone inspection within the distance interval of the fault point.

[0082] The distance interval of the fault point is [L x , L d ],in:

[0083]

[0084] Where, L x is the minimum distance, L d is the maximum distance.

[0085] For example, it is known that a BC phase-to-phase fault occurs in a 10 kV distribution line, the fault currents are Ia=0A, Ib=6A, Ic=6A, and the actual fault point distance is 1.8 km.

[0086] According to the fault current characteristics, it can be judged that it is a two-phase short-circuit fault between BC phases. Select the 10kV distribution line from the 10kV distribution network line basic parameter database, determine the basic parameters of the 10kV distribution network line, set the equivalent impedance to 2Ω in the large operation mode, set the equivalent impedance to 3Ω in the small operation mode, and set the impedance value per unit length of the line to 0.52Ω / km. Under the operation mode of the main transformer supplying the entire station, the short-circuit impedance of the No. 2 main transformer is 3.5Ω, the CT ratio of the 10kV distribution network line is 600 / 5A, and the rated voltage of the 10kV distribution network line is 10.5kV.

[0087] Without correction, the calculated

[0088] The fault point distance interval is [1.5km, 3.4km] when it is not corrected.

[0089] In the corrected case, determine xZ d is 1.15, xZ x is 1.05, xZ L is 1.05, after correction ZD d 2.3Ω, ZD x 3.15Ω, xZ L 0.55Ω.

[0090] Calculate Zm d 1.49Ω, Zm x 0.64Ω, L x1.16km, L d It is 2.16km, and the corrected fault point distance interval is [1.16km, 2.16km].

[0091] It can be seen from the corrected fault point interval that it is closer to the actual fault point distance.

[0092] A line fault location system for 10kV distribution network, such as Figure 2 As shown, it includes a basic parameter acquisition module, a basic parameter correction module, a target impedance determination module and a fault point determination module, wherein: the basic parameter acquisition module is used to determine the basic parameters of the 10kV distribution network line, the basic parameters include the high-voltage side busbar parameterized equivalent impedance and the line unit length parameterized impedance value, wherein the high-voltage side busbar parameterized equivalent impedance includes the parameterized equivalent impedance under the large operation mode and the parameterized equivalent impedance under the small operation mode; the basic parameter correction module is used to correct the basic parameters and determine the corrected line parameters, the corrected line parameters include the high-voltage side busbar equivalent impedance correction value and the line unit length parameterized impedance value. The correction value of the impedance per unit length of the line, the correction value of the equivalent impedance of the high-voltage side bus includes the correction value of the equivalent impedance under the large operation mode and the correction value of the equivalent impedance under the small operation mode; the target impedance determination module is used to determine the target impedance between the bus and the fault point based on the equivalent impedance correction value of the high-voltage side bus and the short-circuit impedance of the main transformer after determining the fault type, and the fault types include two-phase short circuit and three-phase short circuit; the fault point determination module is used to determine the distance interval of the fault point based on the target impedance between the bus and the fault point and the correction value of the impedance per unit length of the line, and determine the fault point through drone inspection within the distance interval of the fault point.

[0093] An electronic device includes: a processor and a memory, wherein computer program instructions are stored in the memory, and when the computer program instructions are executed by the processor, the processor executes the above-mentioned method for locating line faults in a 10kV distribution network.

[0094] A computer-readable storage medium is used to store a program, and when the program is executed by a processor, the above-mentioned method for locating line faults in a 10kV distribution network is implemented.

[0095] Those skilled in the art will appreciate that embodiments of the present invention may be provided as methods, systems, or computer program products. Therefore, the present invention may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present invention may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0096] The present invention is described with reference to flowcharts and / or block diagrams of systems, devices (systems), and computer program products according to embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, as well as the combination of processes and / or blocks in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0097] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0098] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0099] Although the preferred embodiments of the present invention have been described, those skilled in the art may make other changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0100] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A method for locating line faults in a 10kV distribution network, characterized in that: The following steps are involved: Determine the basic parameters of the 10kV distribution network line, the basic parameters include the high-voltage side busbar parameterized equivalent impedance and the line unit length parameterized impedance value, wherein the high-voltage side busbar parameterized equivalent impedance includes the parameterized equivalent impedance in the large operation mode and the parameterized equivalent impedance in the small operation mode; Correcting the basic parameters to determine corrected line parameters, wherein the corrected line parameters include a correction value of an equivalent impedance of a high-voltage side bus and a correction value of an impedance per unit length of the line, wherein the correction value of an equivalent impedance of a high-voltage side bus includes an equivalent impedance correction value under a large operation mode and an equivalent impedance correction value under a small operation mode; After determining the fault type, determining the target impedance between the bus and the fault point based on the high-voltage side bus equivalent impedance correction value and the main transformer short-circuit impedance, the fault type includes two-phase short circuit and three-phase short circuit, and the target impedance includes the target impedance under the large operation mode and the target impedance under the small operation mode; The distance interval of the fault point is determined based on the target impedance between the busbar and the fault point and the correction value of the impedance per unit length of the line, and the fault point is determined by drone inspection within the distance interval of the fault point.

2. A method for locating line faults in a 10kV distribution network according to claim 1, characterized in that: The method of determining the basic parameters of the 10kV distribution network line comprises the following steps: Obtain the system topology structure under the large operation mode from the dispatching platform, and determine the parameter equivalent impedance under the large operation mode from the 10kV distribution network line basic parameter database based on the system topology structure under the large operation mode; Obtain the partial topology structure of the system used in the small operation mode from the dispatching platform, and determine the parameter equivalent impedance in the small operation mode from the 10kV distribution network line basic parameter database based on the partial topology structure of the system used in the small operation mode; Based on the line model, the line unit length parameter impedance value is obtained from the 10kV distribution network line basic parameter database.

3. The method for locating line faults in a 10kV distribution network according to claim 1, characterized in that: The method for determining the corrected line parameters is as follows: Determine basic parameter correction data, wherein the basic parameter correction data includes an equivalent impedance correction coefficient in a large operation mode, an equivalent impedance correction coefficient in a small operation mode, and a line unit length impedance correction coefficient; The basic parameters are corrected based on the basic parameter correction data.

4. A method for locating line faults in a 10kV distribution network according to claim 3, characterized in that: The method for obtaining the equivalent impedance correction value in the large operation mode, the equivalent impedance correction value in the small operation mode and the line unit length impedance correction value is as follows: Among them, ZC d To determine the equivalent impedance in the large operation mode, ZC x To set the equivalent impedance in the small operation mode, ZC L The impedance per unit length of the line is determined by ZD d is the equivalent impedance correction value in the large operation mode, ZD x is the equivalent impedance correction value in the small operation mode, ZD L is the correction value of line impedance per unit length, xZ d is the equivalent impedance correction factor in the large operating mode, xZ x is the equivalent impedance correction factor in the small operation mode, xZ L It is the correction factor of line impedance per unit length.

5. The method for locating line faults in a 10kV distribution network according to claim 3, characterized in that: The method for determining the equivalent impedance correction factor in the large operation mode is as follows: Obtaining basic operating parameters of the 10kV distribution network system, wherein the basic operating parameters include the system commissioning time, the system's ambient temperature change curve, and the system's ambient humidity change curve; Obtaining large operation characteristic parameters of the 10 kV distribution network when operating in a large operation mode, wherein the large operation characteristic parameters include a load fluctuation rate and a load equipment temperature change curve; Based on the system commissioning time, a large operation mode equivalent impedance correction coefficient comparison data set corresponding to the system commissioning time is obtained from the 10kV distribution network line basic parameter database, wherein the large operation mode equivalent impedance correction coefficient comparison data set includes a plurality of large operation mode correction coefficient matching data, and the large operation mode correction coefficient matching data includes a system ambient temperature change matching curve, a system ambient humidity change matching curve, a large operation mode system load average fluctuation rate, and a large operation mode load equipment average temperature change curve; The most matching large operation mode correction coefficient matching data is determined, and the equivalent impedance correction coefficient under the large operation mode corresponding to the large operation mode correction coefficient matching data is obtained from the 10kV distribution network line basic parameter database.

6. A method for locating line faults in a 10kV distribution network according to claim 3, characterized in that: The method for determining the equivalent impedance correction factor in the small operation mode is as follows: Obtaining basic operating parameters of the 10kV distribution network system, wherein the basic operating parameters include the system commissioning time, the system's ambient temperature change curve, and the system's ambient humidity change curve; Obtaining small operation characteristic parameters of the 10 kV distribution network when operating in a small operation mode, wherein the small operation characteristic parameters include a partial topology structure used by the system and system frequency stability; Based on the system commissioning time, a small operation mode equivalent impedance correction coefficient comparison data set corresponding to the system commissioning time is obtained from the 10kV distribution network line basic parameter database, wherein the small operation mode equivalent impedance correction coefficient comparison data set includes a plurality of small operation mode correction coefficient matching data, and the small operation mode correction coefficient matching data includes a system ambient temperature change matching curve, a system ambient humidity change matching curve, a small operation mode system using a partial topology structure, and a small operation mode system frequency stability; The most matching small operation mode correction coefficient matching data is determined, and the equivalent impedance correction coefficient under the small operation mode corresponding to the small operation mode correction coefficient matching data is obtained from the 10kV distribution network line basic parameter database.

7. A method for locating line faults in a 10kV distribution network according to claim 3, characterized in that: The method for determining the correction factor of line impedance per unit length is as follows: Acquire environmental change data of the line, wherein the environmental change data of the line includes a system environmental temperature change curve, a system environmental humidity change curve, a line environmental wind force change curve, and a line environmental light radiation intensity change curve; Obtain the system commissioning time, and based on the system commissioning time, obtain a line environment change matching data set corresponding to the system commissioning time from the 10kV distribution network line basic parameter database, wherein the line environment change matching data set includes a plurality of line environment change matching data, and the line environment change matching data includes a system environment temperature change matching curve, a system environment humidity change matching curve, a line environment wind force change matching curve, and a line environment light radiation intensity change matching curve; Based on the sliding window comparison, the most matching line environment change matching data is determined, and the line unit length impedance value correction coefficient corresponding to the line environment change matching data is obtained from the 10kV distribution network line basic parameter database.

8. The method for locating line faults in a 10 kV distribution network according to claim 3, characterized in that: When the fault type is two-phase short circuit, the method for obtaining the target impedance is: When the fault type is three-phase short circuit, the method for obtaining the target impedance is: Among them, V e is the rated voltage of the 10kV distribution network line, I f2 is the two-phase short-circuit current, I f3 is the three-phase short-circuit current, ZD d To determine the equivalent impedance in the large operation mode, ZD x is the equivalent impedance parameterized in the small operation mode, Z z is the short-circuit impedance of the main transformer, N is the CT ratio of the 10kV distribution network line, Zm d is the target impedance in the large operation mode, Zm x is the target impedance in the small operation mode, and θ is the phase angle.

9. A method for locating line faults in a 10kV distribution network according to claim 7, characterized in that: The distance interval of the fault point is [L x ,L d ],in: Where, L x is the minimum distance, L d is the maximum distance.

10. A line fault location system for a 10kV distribution network, characterized in that: It includes a basic parameter acquisition module, a basic parameter correction module, a target impedance determination module and a fault point determination module, wherein: The basic parameter acquisition module is used to determine the basic parameters of the 10kV distribution network line, and the basic parameters include the high-voltage side busbar parameterized equivalent impedance and the line unit length parameterized impedance value, wherein the high-voltage side busbar parameterized equivalent impedance includes the parameterized equivalent impedance in the large operation mode and the parameterized equivalent impedance in the small operation mode; The basic parameter correction module is used to correct the basic parameters and determine the corrected line parameters, wherein the corrected line parameters include the high-voltage side busbar equivalent impedance correction value and the line unit length impedance correction value, and the high-voltage side busbar equivalent impedance correction value includes the equivalent impedance correction value under the large operation mode and the equivalent impedance correction value under the small operation mode; The target impedance determination module is used to determine the target impedance between the bus and the fault point based on the high-voltage side bus equivalent impedance correction value and the main transformer short-circuit impedance after determining the fault type, and the fault type includes two-phase short circuit and three-phase short circuit; The fault point determination module is used to determine the fault point distance interval based on the target impedance between the busbar and the fault point and the line unit length impedance value correction value, and determine the fault point within the fault point distance interval through drone inspection.

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