Operation maintenance method and system of power distribution network

Abstract

The invention provides a power distribution network operation maintenance method and system, and relates to the technical field of power distribution network operation maintenance, and the method comprises the steps: starting fault detection of a power transmission cable in a power distribution network, transmitting a fault detection signal, and receiving a reflection signal; performing channel equalization on the reflected signal to obtain an equalized reflected signal, determining a transmission attenuation characteristic according to the equalized reflected signal, and determining a cable fault position of a target power transmission cable in the power distribution network based on the transmission attenuation characteristic; acquiring three-phase current of the target power transmission cable, performing time-frequency feature extraction on the three-phase current to obtain time-frequency fault features of the target power transmission cable, and determining a cable fault type of the target power transmission cable according to the time-frequency fault features; the fault maintenance strategy of the target power transmission cable is generated through the fault position and the cable fault type, accurate fault positioning and diagnosis can be rapidly carried out on the power transmission cable in the power distribution network, and therefore the maintenance strategy of the power transmission cable is generated, and the operation reliability of an operation maintenance system is improved.

Description

Technical Field

[0001] The present application relates to the technical field of distribution network operation and maintenance, and more specifically, to a distribution network operation and maintenance method and system. Background Art

[0002] The operation and maintenance of the distribution network is an important part of ensuring stable, safe and efficient power supply. The distribution network usually includes substations, distribution lines, power transformers, switchgear and related facilities. It converts high-voltage electricity into low-voltage electricity suitable for user needs and transmits it to end users through cables or overhead lines. Effective operation and maintenance not only requires regular inspection, fault diagnosis and repair of equipment, but also involves multiple aspects such as optimal scheduling of power grid loads, line operation monitoring, and management of automation equipment.

[0003] Operation and maintenance personnel need to regularly or irregularly inspect the equipment in the distribution network, including substations, distribution lines, distribution transformers, switchgear, etc., to ensure that the equipment is in good operating condition. For sudden faults, operation and maintenance personnel need to quickly identify the fault type and location through the fault detection system, and take corresponding repair measures to ensure that the system can quickly restore power supply. However, due to the wide and complex coverage of the transmission cables in the distribution network, the diagnosis and repair of transmission cable faults are very difficult. In some remote areas, the power supply lines are long and the environment is complex, and the operating stability of the transmission cables is difficult to guarantee. After a fault occurs, it is impossible to locate and judge the fault of the transmission cable in time, and the subsequent maintenance is difficult. Therefore, how to quickly and accurately locate and diagnose the faults of the transmission cables in the distribution network, so as to generate a maintenance strategy for the transmission cables, so as to improve the operating reliability of the operation and maintenance system is a difficult problem faced by the industry. Summary of the invention

[0004] The present application provides a distribution network operation and maintenance method and system, which can quickly and accurately locate and diagnose faults of transmission cables in the distribution network, thereby generating a maintenance strategy for the transmission cables to improve the operational reliability of the operation and maintenance system.

[0005] In a first aspect, the present application provides an operation and maintenance method for a distribution network, the maintenance method comprising the following steps:

[0006] Initiate fault detection of a transmission cable in the distribution network, send a fault detection signal to a target transmission cable in the distribution network, and then receive a reflection signal of the fault detection signal;

[0007] Performing channel equalization on the reflected signal to obtain an equalized reflected signal, determining a transmission attenuation characteristic of the reflected signal in a target transmission cable according to the equalized reflected signal, and determining a cable fault position of the target transmission cable in the distribution network based on the transmission attenuation characteristic;

[0008] Acquire the three-phase current of the target transmission cable, extract the time-frequency characteristics of the three-phase current, obtain the time-frequency fault characteristics of the target transmission cable, and determine the cable fault type of the target transmission cable according to the time-frequency fault characteristics;

[0009] A fault maintenance strategy for the target power transmission cable is generated according to the cable fault location and the cable fault type.

[0010] In this embodiment, a fault detection signal is sent to a target transmission cable in the distribution network by a pulse signal generator.

[0011] In this embodiment, the reflected signal of the fault detection signal is received by a spectrum analyzer.

[0012] In this embodiment, performing channel equalization on the reflected signal to obtain the equalized reflected signal specifically includes:

[0013] Extracting a channel impulse response and a channel interference noise of the reflected signal;

[0014] Channel equalization is performed on the reflected signal based on the channel impulse response and the channel interference noise to obtain an equalized reflected signal.

[0015] In this embodiment, determining the transmission attenuation characteristic of the reflected signal in the target power transmission cable according to the equalized reflected signal specifically includes:

[0016] Extracting the angular frequency of the equalized reflected signal;

[0017] Determining a signal attenuation coefficient of the equalized reflected signal according to the signal frequency of the equalized reflected signal;

[0018] The transmission attenuation characteristics of the reflected signal in the target power transmission cable are determined according to the angular frequency, the signal attenuation coefficient and the electrical parameters of the target power transmission cable.

[0019] In this embodiment, determining the cable fault location of the target transmission cable in the distribution network based on the transmission attenuation characteristic specifically includes:

[0020] determining a fault detection delay for a target transmission cable;

[0021] Determine a cable fault occurrence distance of a target power transmission cable according to the fault detection delay and the transmission attenuation characteristic;

[0022] Obtaining the deployment information of transmission cables in the distribution network;

[0023] A cable fault location of a target transmission cable in a distribution network is determined based on the cable fault occurrence distance and the transmission cable deployment information.

[0024] In this embodiment, the three-phase current of the target transmission cable is obtained by an intelligent current sensor.

[0025] In this embodiment, the time-frequency feature extraction of the three-phase current is performed by using wavelet packet transform to extract the time-frequency feature of the three-phase current.

[0026] In this embodiment, determining the cable fault type of the target transmission cable according to the time-frequency fault feature is to input the time-frequency fault feature into a fault diagnosis model for fault classification, thereby obtaining the cable fault type of the target transmission cable.

[0027] In a second aspect, the present application provides an operation and maintenance system for a distribution network, which is used to perform an operation and maintenance method for a distribution network, and the maintenance system includes:

[0028] A detection signal sending module, used to start fault detection of a transmission cable in the distribution network, send a fault detection signal to a target transmission cable in the distribution network, and then receive a reflection signal of the fault detection signal;

[0029] a fault location module, configured to perform channel equalization on the reflected signal to obtain an equalized reflected signal, determine a transmission attenuation characteristic of the reflected signal in a target transmission cable according to the equalized reflected signal, and determine a cable fault location of the target transmission cable in the distribution network based on the transmission attenuation characteristic;

[0030] A fault type judgment module is used to obtain the three-phase current of the target transmission cable, extract the time-frequency characteristics of the three-phase current, obtain the time-frequency fault characteristics of the target transmission cable, and determine the cable fault type of the target transmission cable according to the time-frequency fault characteristics;

[0031] A maintenance strategy generating module is used to generate a fault maintenance strategy for a target transmission cable according to the cable fault location and the cable fault type.

[0032] The technical solution provided by the embodiments disclosed in this application has the following beneficial effects:

[0033] By starting fault detection of the transmission cable in the distribution network, a fault detection signal is sent to the target transmission cable in the distribution network, and then a reflected signal of the fault detection signal is received; channel equalization is performed on the reflected signal to obtain the equalized reflected signal, and the transmission attenuation characteristics of the reflected signal in the target transmission cable are determined according to the equalized reflected signal, and the cable fault position of the target transmission cable in the distribution network is determined based on the transmission attenuation characteristics; the three-phase current of the target transmission cable is obtained, and the time-frequency characteristics of the three-phase current are extracted to obtain the time-frequency fault characteristics of the target transmission cable, and the cable fault type of the target transmission cable is determined according to the time-frequency fault characteristics; and a fault maintenance strategy for the target transmission cable is generated according to the cable fault position and the cable fault type.

[0034] It can be seen that in the present application, firstly, in the transmission cable of the distribution network, the reflected signal may be affected by factors such as noise, interference and line characteristics. Through channel equalization, the influence of these factors on the reflected signal can be effectively reduced, and the characteristics closer to the original signal can be restored, which provides a more accurate signal input for subsequent fault location, thereby improving the measurement accuracy of the fault location. Through the signal after channel equalization, the transmission attenuation characteristics of the signal in the transmission cable can be more clearly analyzed. Based on the transmission attenuation characteristics of the signal, the loss occurring during the signal propagation process can be estimated more accurately, thereby inferring the specific location of the fault, thereby greatly improving the accuracy of fault location. Then, by obtaining the three-phase current of the target transmission cable and analyzing the three-phase current through the time-frequency feature extraction method, the potential fault characteristics in the transmission cable can be captured more accurately. The time-frequency fault characteristics have high time resolution and frequency resolution, and can quickly detect the occurrence of faults when the current waveform changes transiently, and quickly identify the specific type of fault, which helps the distribution network operation and maintenance system to respond quickly; finally, the fault maintenance strategy of the target transmission cable is generated according to the cable fault location and cable fault type, and accurate repair plans can be formulated according to different fault conditions, thereby significantly improving the overall operation efficiency of the distribution network and the reliability of the operation and maintenance system.

[0035] In summary, the technical solution adopted in the present application can quickly and accurately locate and diagnose faults of transmission cables in the distribution network, thereby generating a maintenance strategy for the transmission cables to improve the operational reliability of the operation and maintenance system. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The drawings described herein are used to provide a further understanding of the embodiments of the present invention, constitute a part of this application, and do not constitute a limitation of the embodiments of the present invention. In the drawings:

[0037] Figure 1 It is a flow chart of the operation and maintenance method of the distribution network provided by this application;

[0038] Figure 2 is an exemplary flow chart for determining the transmission attenuation characteristics of a fault detection signal in a target power transmission cable according to the present application;

[0039] Figure 3 It is a module structure diagram of the operation and maintenance system of the distribution network provided in this application. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical scheme and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments and drawings. The schematic implementation modes and descriptions of the present invention are only used to explain the present invention and are not intended to limit the present invention. It should be noted that the present invention is already in the actual development and use stage.

[0041] Embodiment 1: In order to better understand the above technical solution, the above technical solution will be described in detail below in conjunction with the accompanying drawings and specific implementation methods. Figure 1 As shown, this figure is an exemplary flow chart of an operation and maintenance method of a distribution network shown in this embodiment of the present application, and the maintenance method includes the following steps:

[0042] In step S1, fault detection of a power transmission cable in a distribution network is started, a fault detection signal is sent to a target power transmission cable in the distribution network, and then a reflection signal of the fault detection signal is received.

[0043] In specific implementation, a fault detection signal can be sent to a target transmission cable in a distribution network through a pulse signal generator; first, the pulse signal generator is connected to the input end of the target transmission cable in the distribution network. The pulse signal generator can generate a pulse signal that rises and falls rapidly and has a strong time domain resolution, which is suitable for locating faults in transmission cables in the distribution network; then, the pulse signal generator is started to emit a series of high-frequency pulse signals. These pulse signals will propagate along the target transmission cable and will be reflected when a fault point occurs. The fault point may include a broken line, a short circuit, a grounding, etc. The pulse signal will be reflected when encountering these fault points and reflected back to the source.

[0044] In addition, in the specific implementation, the reflected signal of the fault detection signal can be received by a spectrum analyzer; first, the input end of the spectrum analyzer is connected to the target transmission cable in the distribution network to ensure that it can receive the signal reflected back from the transmission cable, that is, the reflected signal of the fault detection signal.

[0045] In step S2, channel equalization is performed on the reflected signal to obtain an equalized reflected signal, a transmission attenuation characteristic of the reflected signal in a target transmission cable is determined according to the equalized reflected signal, and a cable fault position of the target transmission cable in the distribution network is determined based on the transmission attenuation characteristic.

[0046] In this embodiment, channel equalization is performed on the reflected signal to obtain the equalized reflected signal in the following manner, namely:

[0047] Extracting a channel impulse response and a channel interference noise of the reflected signal;

[0048] Channel equalization is performed on the reflected signal based on the channel impulse response and the channel interference noise to obtain an equalized reflected signal.

[0049] In specific implementation, first, the channel impulse response and channel interference noise of the reflected signal can be extracted, wherein the channel impulse response is a mathematical model that describes the influence of the channel on the reflected signal during the propagation of the reflected signal. The reflected signal is sampled to capture the time domain change of the reflected signal, and the channel response is extracted from the received reflected signal by the minimum square error method. The channel impulse response can also be calculated by sending a known signal and receiving the difference of the reflected signal. The channel interference noise of the reflected signal can be estimated by a noise estimation algorithm (such as Wiener filtering); then, the reflected signal can be channel equalized based on the channel impulse response and the channel interference noise. The goal of channel equalization is to eliminate or compensate for the distortion, attenuation, interference and other problems caused by the channel during the propagation of the reflected signal. In actual implementation, the equalized reflected signal can be determined by the following formula:

[0050] y'(n)=h(n)*y(n)+v(n)

[0051] Wherein, y′(n) represents the reflected signal after equalization, y(n) represents the original reflected signal, h(n) represents the channel impulse response, and v(n) represents the channel interference noise.

[0052] Preferably, in this embodiment, reference Figure 2 As shown in FIG. 1 , this figure is an exemplary flow chart of determining the transmission attenuation characteristics of the fault detection signal in the target transmission cable in an embodiment of the present application. In this embodiment, the transmission attenuation characteristics of the reflected signal in the target transmission cable are determined according to the equalized reflected signal, which can be implemented by the following steps:

[0053] First, in step S21, the angular frequency of the equalized reflected signal is extracted;

[0054] Then, in step S22, a signal attenuation coefficient of the equalized reflected signal is determined according to the signal frequency of the equalized reflected signal;

[0055] Finally, in step S23, the transmission attenuation characteristics of the reflected signal in the target power transmission cable are determined according to the angular frequency, the signal attenuation coefficient and the electrical parameters of the target power transmission cable.

[0056] In specific implementation, first, the equalized reflected signal needs to be converted from the time domain to the frequency domain, which can be converted by fast Fourier transform, so that the angular frequency of the equalized reflected signal can be extracted, wherein the angular frequency reflects the rate of change of the equalized reflected signal in the frequency domain, and the product of the frequency of the equalized reflected signal and 2π can be used as the angular frequency of the equalized reflected signal; then, the signal attenuation coefficient of the equalized reflected signal can be determined by the signal frequency of the equalized reflected signal, wherein the signal attenuation coefficient is an indicator for measuring the degree of energy loss of the equalized reflected signal during transmission. In actual implementation, the signal attenuation coefficient can be determined by the following formula:

[0057]

[0058] Among them, α represents the signal attenuation coefficient of the reflected signal after equalization, c represents the speed of light, and f represents the signal frequency of the reflected signal after equalization; finally, the transmission attenuation characteristics of the reflected signal in the target transmission cable can be determined according to the angular frequency, the signal attenuation coefficient and the electrical parameters of the target transmission cable, wherein the transmission attenuation characteristics represent the attenuation rate of the reflected signal in the target transmission cable, and the electrical parameters of the target transmission cable refer to resistance, inductance, capacitance and conductance. In actual implementation, the transmission attenuation characteristics can be determined by the following formula:

[0059]

[0060] Among them, γ represents the transmission attenuation characteristics of the reflected signal in the target transmission cable, α represents the signal attenuation coefficient, ω represents the angular frequency, R represents the resistance of the target transmission cable, D represents the conductance of the target transmission cable, H represents the inductance of the target transmission cable, and C represents the capacitance of the target transmission cable.

[0061] In this embodiment, the cable fault location of the target transmission cable in the distribution network can be determined based on the transmission attenuation characteristics in the following manner, namely:

[0062] determining a fault detection delay for a target transmission cable;

[0063] Determine a cable fault occurrence distance of a target power transmission cable according to the fault detection delay and the transmission attenuation characteristic;

[0064] Obtaining the deployment information of transmission cables in the distribution network;

[0065] A cable fault location of a target transmission cable in a distribution network is determined based on the cable fault occurrence distance and the transmission cable deployment information.

[0066] In specific implementation, first, the fault detection delay of the target transmission cable can be determined. The fault detection delay refers to the time from sending the fault detection signal to receiving the reflected signal during the fault detection process. The fault detection delay of the target transmission cable can be obtained by comparing the signal timestamp; then, the cable fault occurrence distance of the target transmission cable can be determined according to the fault detection delay and the transmission attenuation characteristics. The cable fault occurrence distance can be determined by the following formula:

[0067]

[0068] Among them, d represents the distance of cable fault occurrence, t represents the fault detection delay, γ represents the transmission attenuation characteristics, and ω represents the angular frequency; furthermore, the transmission cable deployment information in the distribution network can be obtained, and the transmission cable deployment information includes the laying path, length, path changes (such as turns, connection nodes, etc.), starting and ending positions, and possible access points, distribution stations, etc. of the transmission cables in the distribution network; finally, the cable fault location of the target transmission cable in the distribution network can be determined based on the cable fault distance and the transmission cable deployment information, that is, the calculated cable fault distance and the transmission cable deployment information in the distribution network are input into the GIS system of the distribution network, and the cable fault location of the target transmission cable in the distribution network can be inferred.

[0069] It should be noted that in the transmission cables of the distribution network, the reflected signal may be affected by factors such as noise, interference and line characteristics. Through channel equalization, the impact of these factors on the reflected signal can be effectively reduced, and the characteristics closer to the original signal can be restored. This provides a more accurate signal input for subsequent fault location, thereby improving the measurement accuracy of the fault location. The signal after channel equalization can more clearly analyze the transmission attenuation characteristics of the signal in the transmission cable. Based on the transmission attenuation characteristics of the signal, the loss occurring during the signal propagation process can be more accurately estimated, thereby inferring the specific location of the fault, thereby greatly improving the accuracy of fault location, so that repair measures can be taken quickly.

[0070] In step S3, the three-phase current of the target transmission cable is obtained, and the time-frequency characteristics of the three-phase current are extracted to obtain the time-frequency fault characteristics of the target transmission cable, and the cable fault type of the target transmission cable is determined according to the time-frequency fault characteristics.

[0071] In specific implementation, the three-phase current of the target transmission cable can be obtained through the intelligent current sensor; the signal of the three-phase current is usually a time domain signal. During the monitoring process, it is necessary to obtain and record the real-time waveform of the three-phase current. The intelligent current sensor can be installed on the three-phase current path of the target transmission cable, usually at the cable inlet and outlet distribution box, substation or branch distribution point.

[0072] In this embodiment, the time-frequency feature extraction of the three-phase current is to extract the time-frequency feature of the three-phase current by wavelet packet transform, and then obtain the time-frequency fault feature of the target transmission cable; it should be noted that in this application, the time-frequency fault feature is the feature that represents the change of the signal frequency component of the target transmission cable in the time domain. For the fault analysis of the three-phase current, the change of the frequency component can help identify different types of faults (such as short circuit, ground fault, etc.); wavelet packet transform is a multi-scale analysis method that can effectively decompose the signal into sub-signals of different frequency bands and can capture the time-frequency characteristics of the signal. ; In specific implementation, the current signal of each phase in the three-phase current is decomposed by wavelet packet to obtain sub-signals of different frequency bands. The signal is decomposed into multiple frequency band levels (low frequency, medium frequency and high frequency) and sub-bands of each frequency band through wavelet packet transform. The number of layers of wavelet packet transform determines the fineness of the decomposed frequency band. Usually 3 to 5 layers are selected for analysis to balance the computational complexity and frequency band resolution. After wavelet packet transform, sub-signals of the signal in different frequency bands are obtained; then, the spectrum information of each sub-signal can be analyzed, so that the spectrum analysis results can be used as the time-frequency fault characteristics of the target transmission cable.

[0073] In this embodiment, determining the cable fault type of the target transmission cable according to the time-frequency fault characteristics is to input the time-frequency fault characteristics into a fault diagnosis model for fault classification, thereby obtaining the cable fault type of the target transmission cable; in specific implementation, first, in order to classify the fault type of the target transmission cable by the time-frequency fault characteristics, it is necessary to construct a suitable fault diagnosis model. The fault diagnosis model used in this application is a recurrent neural network model based on an attention mechanism. The recurrent neural network model based on an attention mechanism is particularly suitable for complex pattern recognition tasks. Through a multi-layer neuron structure, the neural network can model complex time-frequency fault characteristics and perform efficient classification; then, the time-frequency fault characteristics can be input into the fault diagnosis model for prediction. The model will output the prediction result of the fault type based on the obtained characteristics and classification rules, so that according to the prediction result, the cable fault type of the target transmission cable can be determined, such as short circuit, ground fault, open circuit fault, etc.

[0074] It should be noted that by obtaining the three-phase current of the target transmission cable and analyzing the three-phase current through the time-frequency feature extraction method, the potential fault characteristics in the transmission cable can be captured more accurately. The time-frequency fault characteristics have high time resolution and frequency resolution, and can quickly detect the occurrence of faults when the current waveform changes transiently, and quickly identify the specific type of fault, which helps the distribution network operation and maintenance system to respond quickly, take necessary emergency measures in time, and avoid the spread of faults, thereby improving the overall reliability of the distribution network.

[0075] In step S4, a fault maintenance strategy for the target power transmission cable is generated according to the cable fault location and the cable fault type.

[0076] In specific implementation, first, the time required for maintenance can be estimated through the cable fault location and cable fault type. For example, a short circuit fault may take a long time to be fully inspected and repaired, while a local damage fault may be repaired more quickly. In addition, the required tools and materials should be prepared in advance for different cable fault locations and cable fault types. For example, for an open circuit fault caused by a broken cable, spare cables, connectors, and tools need to be prepared; and for an overload fault, load adjustment and backup power supply configuration may be required. Furthermore, based on the detailed information on the cable fault location and cable fault type, an optimized fault maintenance strategy can be formulated.

[0077] It should be noted that by generating a fault maintenance strategy for the target transmission cable based on the cable fault location and cable fault type, it is possible to formulate an accurate repair plan based on different fault conditions, improve the stability and reliability of the power grid, and minimize the impact of the fault on the distribution network by accurately locating the fault, responding quickly and implementing the maintenance plan, shortening the maintenance time and reducing downtime losses, thereby significantly improving the overall operating efficiency of the distribution network and the reliability of the maintenance system.

[0078] It can be seen that in the present application, firstly, in the transmission cable of the distribution network, the reflected signal may be affected by factors such as noise, interference and line characteristics. Through channel equalization, the influence of these factors on the reflected signal can be effectively reduced, and the characteristics closer to the original signal can be restored, which provides a more accurate signal input for subsequent fault location, thereby improving the measurement accuracy of the fault location. Through the signal after channel equalization, the transmission attenuation characteristics of the signal in the transmission cable can be more clearly analyzed. Based on the transmission attenuation characteristics of the signal, the loss occurring during the signal propagation process can be estimated more accurately, thereby inferring the specific location of the fault, thereby greatly improving the accuracy of fault location. Then, by obtaining the three-phase current of the target transmission cable and analyzing the three-phase current through the time-frequency feature extraction method, the potential fault characteristics in the transmission cable can be captured more accurately. The time-frequency fault characteristics have high time resolution and frequency resolution, and can quickly detect the occurrence of faults when the current waveform changes transiently, and quickly identify the specific type of fault, which helps the distribution network operation and maintenance system to respond quickly; finally, the fault maintenance strategy of the target transmission cable is generated according to the cable fault location and cable fault type, and accurate repair plans can be formulated according to different fault conditions, thereby significantly improving the overall operation efficiency of the distribution network and the reliability of the operation and maintenance system.

[0079] In summary, the technical solution adopted in the present application can quickly and accurately locate and diagnose faults of transmission cables in the distribution network, thereby generating a maintenance strategy for the transmission cables to improve the operational reliability of the operation and maintenance system.

[0080] In an embodiment of the present application, the fault maintenance strategy of the target transmission cable includes: optimizing the grid resources of the grid where the target transmission cable is located according to a pre-configured resource allocation optimization model. The resource allocation optimization model is constructed based on a comprehensive loss index and an emergency resource information set, and the comprehensive loss index is determined based on a partition risk assessment model and grid load data.

[0081] In an optional embodiment of the present application, the process of constructing the partition risk assessment model includes:

[0082] Determine key statistical features in each preset time period, wherein the key statistical features may include statistical features such as variance, average value, difference between maximum and minimum values ​​of various historical power parameter values ​​in the time period, health status of each power grid device, various statistical features of various environmental parameters in the time period, and quantitative values ​​of all geographic information features, such as altitude, slope, land use type, terrain classification index, digital elevation and other information;

[0083] A Bayesian network model is used as a partition risk assessment model, wherein the partition risk assessment model takes key statistical features of each time period as input;

[0084] Use structural learning algorithms to build the structure of the Bayesian network to represent the conditional dependencies between key statistical features and manually add known physical or engineering constraints;

[0085] The partition risk assessment model outputs an estimated probability of failure occurring in each time period according to the key statistical characteristics of the time period; it iteratively optimizes the parameters of each conditional probability table in the Bayesian network by using the maximum likelihood estimation or Bayesian estimation method for each time period;

[0086] In an optional embodiment of the present application, the resource demand ratio Bi is calculated according to the following formula:

[0087]

[0088] Wherein, i represents the serial number mark of each power grid partition; Ri represents the estimated resource demand mark in the i-th power grid partition, and the estimated resource demand Ri=a1×Li+a2×Ni+a3×Ri; wherein a1, a2 and a3 are all preset proportional coefficients; wherein Li represents the real-time power load mark of the i-th power grid partition; Ni represents the number mark of the key power facilities in the i-th power grid partition; FPi represents the failure probability mark of the i-th power grid partition estimated by the partition risk assessment model; Bi represents the resource demand ratio mark in the i-th power grid partition.

[0089] The grid loss index Wherein, a4 and a5 are preset proportional coefficients, and Ltotal is the total load of all grid partitions.

[0090] In an optional embodiment of the present application, the resource allocation optimization model is constructed by minimizing the target optimization function M as the optimization target, and taking the first constraint condition and the second constraint condition as the constraint condition set:

[0091] The expression of the objective optimization function M of the resource allocation optimization model is: M = ∑ i (Si×(1-xi)+Pi×xi); where Pi is the cost of allocating emergency resources to the i-th grid partition; xi represents the allocation ratio variable set for each grid partition; the total amount of emergency resources is 1.

[0092] Embodiment 2: This application provides an operation and maintenance system for a distribution network, referring to Figure 3 As shown, this figure is a schematic diagram of a maintenance system according to this embodiment of the present application, and the maintenance system includes:

[0093] A detection signal sending module 100, used to start fault detection of a transmission cable in the distribution network, send a fault detection signal to a target transmission cable in the distribution network, and then receive a reflection signal of the fault detection signal;

[0094] A fault location module 200 is used to perform channel equalization on the reflected signal to obtain an equalized reflected signal, determine a transmission attenuation characteristic of the reflected signal in a target transmission cable according to the equalized reflected signal, and determine a cable fault location of the target transmission cable in the distribution network based on the transmission attenuation characteristic;

[0095] The fault type judgment module 300 is used to obtain the three-phase current of the target transmission cable, extract the time-frequency characteristics of the three-phase current, obtain the time-frequency fault characteristics of the target transmission cable, and determine the cable fault type of the target transmission cable according to the time-frequency fault characteristics;

[0096] The maintenance strategy generating module 400 is used to generate a fault maintenance strategy for a target transmission cable according to the cable fault location and the cable fault type.

[0097] The specific implementation methods described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above description is only a specific implementation method of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for operating and maintaining a distribution network, characterized in that: The maintenance method comprises the following steps: Initiate fault detection of a transmission cable in the distribution network, send a fault detection signal to a target transmission cable in the distribution network, and then receive a reflection signal of the fault detection signal; Performing channel equalization on the reflected signal to obtain an equalized reflected signal, determining a transmission attenuation characteristic of the reflected signal in a target transmission cable according to the equalized reflected signal, and determining a cable fault position of the target transmission cable in the distribution network based on the transmission attenuation characteristic; Acquire the three-phase current of the target transmission cable, extract the time-frequency characteristics of the three-phase current, obtain the time-frequency fault characteristics of the target transmission cable, and determine the cable fault type of the target transmission cable according to the time-frequency fault characteristics; A fault maintenance strategy for the target power transmission cable is generated according to the cable fault location and the cable fault type.

2. A method for operating and maintaining a distribution network according to claim 1, characterized in that: A fault detection signal is sent to a target transmission cable in the distribution network through a pulse signal generator.

3. The operation and maintenance method of a distribution network according to claim 1, characterized in that: A reflected signal of the fault detection signal is received by a spectrum analyzer.

4. The operation and maintenance method of a distribution network according to claim 1, characterized in that: Performing channel equalization on the reflected signal to obtain the equalized reflected signal specifically includes: extracting a channel impulse response and a channel interference noise of the reflected signal; Channel equalization is performed on the reflected signal based on the channel impulse response and the channel interference noise to obtain an equalized reflected signal.

5. The operation and maintenance method of a distribution network according to claim 1, characterized in that: Determining the transmission attenuation characteristics of the reflected signal in the target power transmission cable according to the equalized reflected signal specifically includes: Extracting the angular frequency of the equalized reflected signal; Determining a signal attenuation coefficient of the equalized reflected signal according to the signal frequency of the equalized reflected signal; The transmission attenuation characteristics of the reflected signal in the target power transmission cable are determined according to the angular frequency, the signal attenuation coefficient and the electrical parameters of the target power transmission cable.

6. The operation and maintenance method of a distribution network according to claim 1, characterized in that: Determining the cable fault location of the target transmission cable in the distribution network based on the transmission attenuation characteristics specifically includes: determining a fault detection delay for a target transmission cable; Determine a cable fault occurrence distance of a target power transmission cable according to the fault detection delay and the transmission attenuation characteristic; Obtaining the deployment information of transmission cables in the distribution network; A cable fault location of a target transmission cable in a distribution network is determined based on the cable fault occurrence distance and the transmission cable deployment information.

7. The method for operating and maintaining a distribution network according to claim 1, characterized in that: The three-phase current of the target transmission cable is obtained through the intelligent current sensor.

8. The operation and maintenance method of a distribution network according to claim 1, characterized in that: The time-frequency feature extraction of the three-phase current is performed by using wavelet packet transform.

9. The operation and maintenance method of a distribution network according to claim 1, characterized in that: Determining the cable fault type of the target transmission cable according to the time-frequency fault characteristics is to input the time-frequency fault characteristics into a fault diagnosis model for fault classification, thereby obtaining the cable fault type of the target transmission cable.

10. An operation and maintenance system for a distribution network, used to execute an operation and maintenance method for a distribution network according to any one of claims 1 to 9, characterized in that: The maintenance system comprises: A detection signal sending module, used to start fault detection of a transmission cable in the distribution network, send a fault detection signal to a target transmission cable in the distribution network, and then receive a reflection signal of the fault detection signal; a fault location module, configured to perform channel equalization on the reflected signal to obtain an equalized reflected signal, determine a transmission attenuation characteristic of the reflected signal in a target transmission cable according to the equalized reflected signal, and determine a cable fault location of the target transmission cable in the distribution network based on the transmission attenuation characteristic; A fault type judgment module is used to obtain the three-phase current of the target transmission cable, extract the time-frequency characteristics of the three-phase current, obtain the time-frequency fault characteristics of the target transmission cable, and determine the cable fault type of the target transmission cable according to the time-frequency fault characteristics; A maintenance strategy generating module is used to generate a fault maintenance strategy for a target transmission cable according to the cable fault location and the cable fault type.

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