Power distribution system insulation condition analysis method and system

Abstract

The embodiment of the application discloses a power distribution system insulation state analysis method and system, the method comprises the following steps: injecting wideband voltage into the power distribution system at different output frequencies; obtaining the operation parameters of the power distribution system; determining the first insulation state of the power distribution line according to the wideband voltage and the line wideband zero sequence current; determining the ground fault state of the power distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current; determining the second insulation state of the bus based on the three-phase bus impulse voltage and the three-phase bus power frequency voltage; determining the third insulation state of the transformer low-voltage winding based on the transformer secondary side three-phase wideband current and the wideband voltage; outputting the operation and maintenance strategy based on each insulation state. Through the above method, the insulation state of the power distribution network can be monitored online, the insulation state of the power distribution system can be comprehensively evaluated, a solution is provided for the change from emergency maintenance to active operation and maintenance of the power distribution system, and the operation and maintenance efficiency, accuracy and power supply reliability are improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of power systems, and particularly relates to a power distribution system insulation state analysis method and system. BACKGROUND

[0002] In the operation process of a power system, insulation failure is the most common main fault form. Unlike a power transmission network, a distribution line is erected at a low height and is easily affected by the channel environment, and insulation failure occurs. At the beginning of the insulation failure of the distribution line, there is no obvious change in system voltage, current and the like, and it is difficult to detect. The insulation performance continues to decline after the insulation failure point develops continuously, and eventually causes single-phase grounding fault, phase-to-phase short circuit fault and the like. For the frequent insulation failure of the distribution line, the most fundamental solution is effective operation and maintenance of the distribution line. Through efficient operation and maintenance, insulation hazards can be effectively investigated, and the probability of insulation failure of the distribution line can be greatly reduced. However, the operation and maintenance of the distribution line is difficult, and the hazards are difficult to find. Blind comprehensive operation and maintenance is inefficient, and requires extremely high labor cost and time cost. In actual work, the operation and maintenance of the distribution line appears "maintenance instead of repair", and the operation and maintenance personnel are overwhelmed by various faults, and the efficiency is extremely low. How to achieve accurate operation and maintenance and efficient operation and maintenance is an old and difficult problem that plagues the operation and maintenance personnel of the power distribution system.

[0003] The bus switch cabinet is an important operation equipment of the power distribution system. Once the switch cabinet has insulation failure, phase-to-phase short circuit is easily caused, and the safe operation of the main transformer is threatened, so insulation monitoring of the switch cabinet is extremely necessary. However, the switch cabinet is strictly closed, and it is difficult to observe and maintain.

[0004] The transformer is a key equipment in the power system. The sudden failure of the transformer in the operation process seriously affects the safety and stability of the power system, and can cause significant asset loss and large-area power outage. Transformer-related accidents show that insulation damage is one of the main causes of accidents. In operation, the transformer is inevitably subjected to short-circuit current impact, and the winding will bear huge and uneven axial and radial electric power. When there is a weak link in the internal mechanical structure of the winding, the cumulative effect of the short-circuit power impact will inevitably cause winding deformation. The winding deformation includes axial and radial size change, body displacement, inter-turn short circuit and winding distortion, bulging and the like. After the winding of the transformer is deformed, the insulation capacity is reduced. If it is not found in time, continued operation can cause sudden damage, insulation breakdown and the like.

[0005] The above problems are common problems in the power distribution system, cover the main equipment, lines and the like of the power distribution system, and can be uniformly summarized as the insulation monitoring problem of the power system. A convenient, economical and effective method is urgently needed to timely monitor the above problems on-line. SUMMARY

[0006] The main purpose of the present application is to provide a power distribution system insulation state analysis method and system, which can solve the problem of lack of effective online monitoring method for power distribution system in the prior art.

[0007] To achieve the above-mentioned purpose, the present application provides a power distribution system insulation state analysis method, which comprises:

[0008] injecting wideband voltage into the power distribution system at different output frequencies;

[0009] obtaining the operating parameters of the power distribution system, which at least include line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line wideband zero sequence current, and transformer secondary side three-phase wideband current;

[0010] determining the first insulation state of the power distribution line according to the wideband voltage and the line wideband zero sequence current; determining the ground fault state of the power distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current; determining the second insulation state of the bus based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage; determining the third insulation state of the transformer low-voltage winding based on the transformer secondary side three-phase wideband current and the wideband voltage;

[0011] outputting line operation and maintenance strategy, bus operation and maintenance strategy, and transformer operation and maintenance strategy based on the first insulation state, ground fault state, second insulation state, and third insulation state.

[0012] In a feasible implementation manner, the determination of the first insulation state of the power distribution line according to the wideband voltage and the line wideband zero sequence current comprises:

[0013] determining the first angle difference between the line wideband zero sequence current and the wideband voltage of each line under different output frequencies according to the wideband voltage and the line wideband zero sequence current under different output frequencies;

[0014] determining the first dielectric spectrum of each power distribution line under different output frequencies by using the first angle difference and tangent value algorithm;

[0015] when there is a power distribution line whose first dielectric spectrum at the current moment under the same output frequency is greater than the first dielectric spectrum at the last moment, it is determined that the first insulation state of the power distribution line is line insulation fault.

[0016] In a feasible implementation manner, the determination of the ground fault state of the power distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current comprises:

[0017] determining whether there is line ground fault of the power distribution line according to the size of the line power frequency zero sequence current;

[0018] If the power distribution line has a line ground fault, according to the size of the transformer secondary side power frequency current, the fault type and ground fault state of the power distribution line are determined, and the fault type includes a phase-to-phase short circuit fault or a single-phase short circuit fault.

[0019] In a feasible implementation, the second insulation state of the bus is determined based on the three-phase bus impulse voltage and the three-phase bus power frequency voltage, including:

[0020] When the ratio of the amplitude of the three-phase bus impulse voltage of each bus switch cabinet to the three-phase bus power frequency voltage is greater than or equal to a preset multiple threshold value, and the phase of the three-phase bus impulse voltage of each bus switch cabinet is greater than a preset phase threshold value, it is determined that the second insulation state of the bus is a bus insulation fault, and the preset phase threshold value is set based on the phase of the three-phase bus power frequency voltage of each bus switch cabinet.

[0021] In a feasible implementation, the third insulation state of the transformer low-voltage winding is determined based on the transformer secondary side three-phase wideband current and the wideband voltage, including:

[0022] The second angle difference between the wideband voltage at different frequencies and the transformer secondary side wideband current of each phase of the transformer is determined using the transformer secondary side wideband current and the wideband voltage at different frequencies.

[0023] The second dielectric spectrum of each phase of the transformer at different frequencies is determined using the second angle difference and the tangent value algorithm.

[0024] The third insulation state of the transformer low-voltage winding is determined according to the second dielectric spectrum of each phase of the transformer at each output frequency.

[0025] In a feasible implementation, the third insulation state of the transformer low-voltage winding is determined according to the second dielectric spectrum of each phase of the transformer at each output frequency, including:

[0026] The first transformer reference dielectric spectrum of each phase of the transformer at different output frequencies is determined when the power distribution system is operating normally.

[0027] If the second dielectric spectrum of the same phase at the same output frequency is greater than the first transformer reference dielectric spectrum, it is determined that the third insulation state of the transformer low-voltage winding is a transformer low-voltage winding insulation fault.

[0028] In a feasible implementation, the first dielectric spectrum of each power distribution line at different output frequencies is determined using the first angle difference and the tangent value algorithm, and then including:

[0029] The line reference dielectric spectrum at different output frequencies when the power distribution system is operating normally is determined.

[0030] Determining a line dielectric spectrum correlation coefficient using the first dielectric spectrum of each distribution line at different output frequencies and the line reference dielectric spectrum, wherein the line dielectric spectrum correlation coefficient is obtained based on a curve showing the first dielectric spectrum changing with different output frequencies and a curve showing the line reference dielectric spectrum changing with different output frequencies;

[0031] If the dielectric spectrum correlation coefficient of any of the distribution lines is less than a first preset correlation coefficient threshold, it is determined that the first insulation state of the distribution line is a line insulation fault.

[0032] In one feasible implementation, the transformer includes a primary side and a secondary side, the primary side includes a high-voltage winding side or a medium-voltage winding side, and the secondary side includes a low-voltage winding side or a medium-voltage winding side. The broadband voltage is injected from the primary side. Then, determining the third insulation state of the transformer low-voltage winding based on the three-phase broadband current and the broadband voltage on the secondary side of the transformer further includes:

[0033] Determine a third angle difference between the broadband voltage on the secondary side and the broadband current on the secondary side of the transformer at different frequencies using the broadband current on the secondary side of the transformer and the broadband voltage at different frequencies;

[0034] Determining a third dielectric spectrum between each phase of the secondary side and the primary side of the transformer at different frequencies using the third angle difference and tangent value algorithm;

[0035] determining a second transformer reference dielectric spectrum between each phase of the secondary side and the primary side at different output frequencies when the power distribution system operates normally;

[0036] determining, based on the third dielectric spectrum at each output frequency and the second transformer reference dielectric spectrum, a transformer dielectric spectrum correlation coefficient between each phase of the secondary side and the primary side of the transformer, the transformer dielectric spectrum correlation coefficient being obtained based on a curve showing how the third dielectric spectrum of the same phase of the secondary side and the primary side varies with different output frequencies and a curve showing how the second transformer reference dielectric spectrum varies with different output frequencies;

[0037] If the dielectric spectrum correlation coefficient of the transformer of any phase is less than a second preset correlation coefficient threshold, it is determined that the third insulation state of the transformer low-voltage winding is an insulation fault of the transformer low-voltage winding.

[0038] In one feasible implementation, based on the first insulation state, outputting a line operation and maintenance strategy includes:

[0039] Performing statistical analysis on a first insulation state of the power distribution line to determine a first insulation fault condition of the power distribution line, wherein the first insulation state includes a line insulation fault;

[0040] When the first insulation fault condition is that there is a power distribution line with an insulation fault number within a preset first time length greater than or equal to a preset first number threshold, a first line operation and maintenance strategy is output, the first line operation and maintenance strategy including recommending strengthening line patrol and finding fault position;

[0041] When the first insulation fault condition is that there is a power distribution line with an insulation fault number within a preset second time length greater than or equal to a preset second number threshold, a second line operation and maintenance strategy is output, the second line operation and maintenance strategy including recommending strengthening line patrol and performing line channel cleaning; the preset first time length is less than the preset second time length, and the preset second number threshold is greater than the preset first number threshold;

[0042] When the first insulation fault condition is that there is a power distribution line with an insulation fault number within a preset third time length greater than or equal to a preset third number threshold, a third line operation and maintenance strategy is output, the third line operation and maintenance strategy including recommending performing line conductor insulation treatment; the preset second time length is less than the preset third time length, and the preset third number threshold is greater than the preset second number threshold.

[0043] In a feasible implementation manner, based on the second insulation state, a busbar operation and maintenance strategy is output, including:

[0044] The second insulation state of the busbar of the power distribution system is statistically analyzed to determine a second insulation fault condition of the busbar, and the second insulation state includes busbar insulation fault;

[0045] When the second insulation fault condition is that there is a busbar insulation fault, a busbar operation and maintenance strategy is output, the busbar operation and maintenance strategy including recommending power-off to check fault condition and develop repair.

[0046] In a feasible implementation manner, based on the third insulation state, a transformer operation and maintenance strategy is output, including:

[0047] When the third insulation state of the transformer is transformer low-voltage winding insulation fault, a transformer operation and maintenance strategy is output, the transformer operation and maintenance strategy including recommending power-off to perform transformer maintenance.

[0048] In a feasible implementation manner, based on the grounding fault state, a line operation and maintenance strategy is output, including:

[0049] The grounding fault state of the power distribution line is statistically analyzed to determine a grounding fault condition of the power distribution line;

[0050] When the grounding fault condition is a distribution line in which the number of line grounding faults existing within a preset fourth duration is greater than or equal to a preset first number threshold and the duration of each line grounding fault is less than or equal to a preset first time threshold, a fourth line operation and maintenance strategy is output, the fourth line operation and maintenance strategy is that the distribution line has intermittent grounding faults, and line channel cleaning is recommended;

[0051] When the grounding fault condition is a distribution line in which the number of line grounding faults existing within a preset fourth duration is greater than or equal to a preset first number threshold and the duration of each line grounding fault is less than or equal to a preset second time threshold, a fifth line operation and maintenance strategy is output, the fifth line operation and maintenance strategy is that the distribution line has foreign object contact, and line channel cleaning and inspection are recommended; the preset second time threshold is greater than the preset first time threshold;

[0052] When the grounding fault condition is a distribution line in which the number of line grounding faults existing within a preset fourth duration is greater than or equal to a preset first number threshold and the duration of each line grounding fault is less than or equal to a preset third time threshold, a sixth line operation and maintenance strategy is output, the sixth line operation and maintenance strategy is that the distribution line has persistent single-phase grounding faults, and line conductor insulation is recommended to be strengthened; the preset third time threshold is greater than the preset second time threshold.

[0053] To achieve the above-mentioned purpose, the second aspect of the present application provides a power distribution system insulation state analysis system, the power distribution system insulation state analysis system comprises:

[0054] A signal injection module is configured to inject broadband voltage into the power distribution system at different output frequencies;

[0055] A parameter monitoring module is configured to obtain operating parameters of the power distribution system, the operating parameters at least including line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current, and transformer secondary side three-phase broadband current;

[0056] A line analysis module is configured to determine a first insulation state of a distribution line according to the broadband voltage and the line broadband zero sequence current, and determine a grounding fault state of the distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current;

[0057] A bus analysis module is configured to determine a second insulation state of a bus based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage;

[0058] A transformer analysis module is configured to determine a third insulation state of a transformer low-voltage winding based on the transformer secondary side three-phase broadband current and the broadband voltage;

[0059] The operation and maintenance policy output module is configured to output a line operation and maintenance policy, a bus operation and maintenance policy, and a transformer operation and maintenance policy based on the first insulation state, the ground fault state, the second insulation state, and the third insulation state.

[0060] To achieve the above object, the third aspect of the present application provides a computer readable storage medium storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the first aspect and any possible implementation.

[0061] To achieve the above object, the fourth aspect of the present application provides a computer device comprising a memory and a processor, wherein the memory stores a computer program, and the computer program, when executed by the processor, causes the processor to perform the steps of the first aspect and any possible implementation.

[0062] By adopting the embodiment of the present application, the following beneficial effects are achieved:

[0063] The present application provides a power distribution system insulation state analysis method, the method comprises: injecting wideband voltage into the power distribution system at different output frequencies; obtaining operating parameters of the power distribution system, the operating parameters at least including line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line wideband zero sequence current, transformer secondary side three-phase wideband current; determining a first insulation state of the power distribution line according to the wideband voltage and the line wideband zero sequence current; determining a ground fault state of the power distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current; determining a second insulation state of the bus based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage; determining a third insulation state of the transformer low-voltage winding based on the transformer secondary side three-phase wideband current and the wideband voltage; outputting a line operation and maintenance policy, a bus operation and maintenance policy, and a transformer operation and maintenance policy based on the first insulation state, the ground fault state, the second insulation state, and the third insulation state. Through the above method, the insulation states of the bus, the power distribution line, and the transformer can be monitored online, the insulation state of the power distribution system can be comprehensively evaluated, and operation and maintenance early warning, suggestions, etc. are given, which provides a technical solution for the transition of the power distribution system from emergency maintenance to active operation and maintenance, realizes precise operation and maintenance of the power distribution system, and improves operation and maintenance efficiency, accuracy, and power supply reliability. BRIEF DESCRIPTION OF DRAWINGS

[0064] In order to more clearly illustrate the technical solutions of the embodiments of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings in the following description only show some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without any creative effort.

[0065] Wherein:

[0066] Figure 1 A flow chart of a power distribution system insulation condition analysis method in an embodiment of the present application;

[0067] Figure 2 Another flow chart of a power distribution system insulation condition analysis method in an embodiment of the present application;

[0068] Figure 3 Still another flow chart of a power distribution system insulation condition analysis method in an embodiment of the present application;

[0069] Figure 4 Still another flow chart of a power distribution system insulation condition analysis method in an embodiment of the present application;

[0070] Figure 5 Still another flow chart of a power distribution system insulation condition analysis method in an embodiment of the present application;

[0071] Figure 6 A structural block diagram of a power distribution system insulation condition analysis system in an embodiment of the present application;

[0072] Figure 7 A structural block diagram of a computer device in an embodiment of the present application. DETAILED DESCRIPTION

[0073] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without any creative work fall within the scope of protection of the present application.

[0074] Please refer to Figure 1 , Figure 1 A flow chart of a power distribution system insulation condition analysis method in an embodiment of the present application; as Figure 1 shown, the method can include the following steps:

[0075] 101, injecting wideband voltage into the power distribution system at different output frequencies;

[0076] It should be noted that the present application can be executed by a control device with control analysis capability, further, the control device can be a power distribution system insulation state analysis system in a power distribution system, or directly executed through the power distribution system, which is not limited herein, and the embodiment is described by taking the application in the power distribution system insulation state analysis system as an example. Further, first, a sweep frequency signal is injected into the power distribution system, the injection of the sweep frequency signal is realized by injecting a wide frequency voltage into the power distribution system at different output frequencies, and the injection of the wide frequency voltage can be realized by a control voltage source, and the voltage source can be a wide frequency voltage source. For example, the output frequency can be varied between 0.001 Hz and 1 MHz.

[0077] 102, obtain the operating parameters of the power distribution system, the operating parameters at least including line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line wide frequency zero sequence current, transformer secondary side three-phase wide frequency current;

[0078] Further, the operating parameters of the power distribution system are also obtained, which are electrical parameters of each electrical element during the operation of the power distribution system, and the operating parameters include but are not limited to line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line wide frequency zero sequence current, transformer secondary side three-phase wide frequency current, zero sequence power frequency voltage, line zero sequence power frequency current, transformer secondary side three-phase power frequency current, and line zero sequence wide frequency current, and the like. For example, the signal acquisition device such as a sensor can be set to monitor the operating parameters of the power distribution system, and the power frequency quantity monitoring and wide frequency voltage and wide frequency current monitoring can be included, wherein the power frequency quantity monitoring can include three-phase bus power frequency voltage, zero sequence power frequency voltage, line zero sequence power frequency current, and transformer secondary side three-phase power frequency current; and the wide frequency voltage and wide frequency current monitoring can include three-phase bus pulse voltage monitoring, transformer secondary side three-phase wide frequency current monitoring, and line zero sequence wide frequency current monitoring.

[0079] 103, according to the wide frequency voltage and the line wide frequency zero sequence current, the first insulation state of the power distribution line is determined; according to the line power frequency zero sequence current and the transformer secondary side power frequency current, the ground fault state of the power distribution line is determined; based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage, the second insulation state of the bus is determined; based on the transformer secondary side three-phase wide frequency current and the wide frequency voltage, the third insulation state of the transformer low-voltage winding is determined;

[0080] It can be understood that after the above operation parameters are obtained, the operation states of the electrical elements of the power distribution system can be evaluated and analyzed through step 103. In this embodiment, the operation states of the power distribution lines, the bus and the transformer in the power distribution system are evaluated and analyzed. Specifically, the first insulation state of the power distribution line is determined through the broadband voltage and the line broadband zero sequence current; the ground fault state of the power distribution line is determined through the line power frequency zero sequence current and the transformer secondary side power frequency current; the second insulation state of the bus is determined through the three-phase bus pulse voltage and the three-phase bus power frequency voltage; and the third insulation state of the low-voltage winding of the transformer is determined through the transformer secondary side three-phase broadband current and the broadband voltage. The first insulation state indicates the insulation condition of the power distribution line, and the first insulation state includes line insulation fault or line insulation normal; the ground fault state indicates the ground fault condition of the power distribution line, and the ground fault state includes line ground fault or line ungrounded fault; the second insulation state indicates the insulation condition of the bus, and the second insulation state includes bus insulation fault or bus insulation normal; and the third insulation state indicates the insulation condition of the transformer, and the third insulation state includes transformer insulation fault or transformer insulation normal.

[0081] 104. Output the line operation and maintenance strategy, the bus operation and maintenance strategy and the transformer operation and maintenance strategy based on the first insulation state, the ground fault state, the second insulation state and the third insulation state.

[0082] It should be noted that after the operation states of the electrical elements in the power distribution system are obtained, the operation and maintenance strategy can be output according to the operation state, that is, after the first insulation state of the power distribution line is obtained, the line operation and maintenance strategy can be output based on the first insulation state; after the ground fault state of the power distribution line is obtained, the line operation and maintenance strategy can be output based on the ground fault state; after the second insulation state of the bus is obtained, the bus operation and maintenance strategy can be output based on the second insulation state; and after the third insulation state of the transformer is obtained, the transformer operation and maintenance strategy can be output based on the third insulation state. Further, the operation and maintenance strategy is used to indicate the maintenance strategy for the operation state of the electrical element. In this embodiment, the line operation and maintenance strategy, the bus operation and maintenance strategy and the transformer operation and maintenance strategy can be output based on the first insulation state, the ground fault state, the second insulation state and the third insulation state, respectively.

[0083] The application provides a power distribution system insulation state analysis method, which comprises the following steps: injecting broadband voltage into a power distribution system at different output frequencies; obtaining operation parameters of the power distribution system, wherein the operation parameters at least include line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current, and transformer secondary side three-phase broadband current; determining a first insulation state of a power distribution line according to the broadband voltage and the line broadband zero sequence current; determining a grounding fault state of the power distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current; determining a second insulation state of a bus based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage; determining a third insulation state of a transformer low-voltage winding based on the transformer secondary side three-phase broadband current and the broadband voltage; and outputting a line operation and maintenance strategy, a bus operation and maintenance strategy and a transformer operation and maintenance strategy based on the first insulation state, the grounding fault state, the second insulation state and the third insulation state. Through the above method, the insulation states of the bus, the power distribution line and the transformer can be monitored online, the insulation state of the power distribution system can be comprehensively evaluated, and operation and maintenance early warning and suggestions can be given, thereby providing a technical solution for changing from emergency maintenance to active operation and maintenance of the power distribution system, realizing accurate operation and maintenance of the power distribution system, and improving operation and maintenance efficiency, accuracy and power supply reliability.

[0084] Please refer to Figure 2 , Figure 2 The application provides another flowchart of a power distribution system insulation state analysis method, as shown in Figure 2 The method shown in Figure 2 may comprise the following steps:

[0085] 201. Injecting broadband voltage into a power distribution system at different output frequencies;

[0086] 202. Obtaining operation parameters of the power distribution system, wherein the operation parameters at least include line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current, and transformer secondary side three-phase broadband current;

[0087] It should be noted that the steps 201 and 202 are similar to the contents of the steps 101 and 102 shown in Figure 1 To avoid repetition, the specific contents can be referred to the contents of the steps 101 and 102 shown in Figure 1 .

[0088] 203. Determining a first angle difference between the line broadband zero sequence current and the broadband voltage of each line at different output frequencies according to the broadband voltage and the line broadband zero sequence current at different output frequencies;

[0089] In the embodiment, the insulation state of the power distribution line is evaluated and analyzed by the dielectric loss value of each line, and therefore, the first angle difference between the line wideband zero sequence current and the wideband voltage of each line at different output frequencies is determined by the wideband voltage and the line wideband zero sequence current at different output frequencies, and the first angle difference represents the phase difference between the line wideband zero sequence current and the wideband voltage. The dielectric loss value of each line is obtained by using the first angle difference.

[0090] 204, determine the first dielectric spectrum of each power distribution line at different output frequencies by using the first angle difference and the tangent value algorithm;

[0091] Further, the first dielectric spectrum of each power distribution line at different output frequencies is determined by using the first angle difference and the tangent value algorithm, and the first dielectric spectrum is the tangent value corresponding to the first angle difference, wherein the tangent value can be used to represent the zero sequence loss degree of the power distribution line, and the tangent value can be used as the dielectric loss value of each line.

[0092] The steps 201, 202, 203 and 204 are illustrated as follows: firstly, in step 201, the wideband voltage at different output frequencies can be obtained by applying a sinusoidal voltage with an output frequency of n and an amplitude of m to the neutral point of the power distribution system; then, in step 202, the system zero sequence voltage (wideband voltage) and the line zero sequence current (line wideband zero sequence current) are obtained, and step 203 is performed, in which the phase difference σ n between the system zero sequence voltage and the line zero sequence current at the output frequency n is obtained. n The tangent value of the phase difference Δδ n is calculated in step 204 to obtain the first dielectric spectrum (line node loss value), wherein the tangent value can be calculated according to the following formula: tan(900-Δδ n ), wherein n represents the number of output frequencies to distinguish different output frequencies, and further, the step s gradually changes the output frequency applied to the neutral point of the system, and the amplitude is kept as s, and steps 202-204 are repeatedly performed to obtain the dielectric spectrum of each line at different output frequencies, wherein the output frequency can vary from 0.1 Hz to 1 MHz, and the amplitude m can be 0-0.5 kV.

[0093] 205, when there is a power distribution line whose first dielectric spectrum at the current time is greater than the first dielectric spectrum at the last time at the same output frequency, it is determined that the first insulation state of the power distribution line is line insulation fault;

[0094] It should be noted that the first dielectric spectrum of each line before and after the fault at the same frequency point is different, therefore, by comparing the size of the first dielectric spectrum of each line before and after the fault at the same frequency point, the first insulation state of the distribution line is determined, and the first dielectric spectrum after the fault is larger than the first dielectric spectrum before the fault, therefore, when the first dielectric spectrum of the distribution line at the current time is larger than the first dielectric spectrum of the distribution line at the last time at the same output frequency, it is determined that the first insulation state of the distribution line is a line insulation fault, that is, the distribution line is an insulation fault line.

[0095] In a feasible implementation manner, after step 204, the first insulation state can also be determined by the correlation coefficient between the first dielectric spectra, and then step 204 can further include A1-A3:

[0096] A1, determining the line reference dielectric spectrum at different output frequencies when the distribution system is in normal operation;

[0097] In the embodiment, when the distribution system is in normal operation, the wideband voltage is injected into the distribution system at different output frequencies, and the line reference dielectric spectrum at different output frequencies when the distribution system is in normal operation is obtained by using the wideband voltage and the line wideband zero sequence current when the distribution system is in normal operation, therefore, the line reference dielectric spectrum at different output frequencies when the distribution system is in normal operation can be further determined, and the line reference dielectric spectrum is used as a reference standard for evaluating the line insulation state.

[0098] A2, determining the line dielectric spectrum correlation coefficient by using the first dielectric spectrum of each distribution line at different output frequencies and the line reference dielectric spectrum, the line dielectric spectrum correlation coefficient being obtained based on the curve of the first dielectric spectrum changing with different output frequencies and the curve of the line reference dielectric spectrum changing with different output frequencies;

[0099] Further, the line dielectric spectrum correlation coefficient is calculated by the obtained line reference dielectric spectrum and the above-mentioned first dielectric spectrum, wherein by different output frequencies, the curve of the first dielectric spectrum changing with different output frequencies and the curve of the line reference dielectric spectrum changing with different output frequencies can be obtained, and then the line dielectric spectrum correlation coefficient is used to represent the correlation degree of the curve of the first dielectric spectrum changing with different output frequencies and the curve of the line reference dielectric spectrum changing with different output frequencies.

[0100] For example, the line dielectric spectrum correlation coefficient can be obtained by the following formula:

[0101]

[0102] wherein, x can represent the first dielectric spectrum, y represents the line reference dielectric spectrum, i represents a certain frequency point, i∈n, n is a set of different frequency points, x can include the first dielectric spectrum of each phase of the power distribution line, and similarly, the first dielectric spectrum can include the line reference dielectric spectrum of each phase of the power distribution line, the line dielectric spectrum correlation coefficient is used to represent the correlation degree of the curve of the first dielectric spectrum with different output frequencies and the curve of the line reference dielectric spectrum with different output frequencies, if the two curves are completely correlated, the correlation coefficient is 1, and if they are completely unrelated, the correlation coefficient is 0.

[0103] A3, if any of the power distribution line dielectric spectrum correlation coefficients is less than the first preset correlation coefficient threshold, it is determined that the first insulation state of the power distribution line is a line insulation fault.

[0104] It can be understood that when the dielectric spectrum correlation degree is small, it can be explained that the first dielectric spectrum is greatly different from the line reference dielectric spectrum when the system is running normally, therefore, if any of the power distribution line dielectric spectrum correlation coefficients is less than the first preset correlation coefficient threshold, it is determined that the first insulation state of the power distribution line is a line insulation fault. Further, taking the first preset correlation coefficient threshold as 0.5, steps A1-A3 are illustrated, the dielectric spectrum of each line at an output frequency of 0.1Hz-1MHz when the system is running normally is calculated and marked as a reference dielectric spectrum (line reference dielectric spectrum); the dielectric spectrum (first dielectric spectrum) of each line at an output frequency of 0.1Hz-1MHz is continuously calculated in real time; further, the correlation coefficient (line dielectric spectrum correlation coefficient) of the real-time dielectric spectrum (first dielectric spectrum) of each line at an output frequency of 0.1Hz-1MHz and the reference dielectric spectrum of each line at an output frequency of 0.1Hz-1MHz is calculated, for example, if the correlation coefficient of the first dielectric spectrum and the reference dielectric spectrum is less than 0.5, it is considered that the line has insulation decline, that is, the first insulation state of the power distribution line is a line insulation fault.

[0105] 206, statistically analyzing the first insulation state of the power distribution line to determine the first insulation fault condition of the power distribution line, the first insulation state including a line insulation fault;

[0106] In this embodiment, data recording is also performed, and the recording content includes but is not limited to the information of the first insulation state of the power distribution line, such as recording the line name and the occurrence time of the insulation decline. Therefore, when outputting the operation and maintenance strategy, the first insulation fault condition of the power distribution line can be determined by statistically analyzing the first insulation state of the power distribution line, and the operation and maintenance strategy can be output by the fault condition, wherein the first insulation state at least includes a line insulation fault.

[0107] 207. When the first insulation fault condition is that there is a distribution line with a number of insulation faults greater than or equal to a preset first number threshold within a preset first time period, outputting a first line operation and maintenance strategy, wherein the first line operation and maintenance strategy includes a suggestion to strengthen line inspection and find the fault location;

[0108] 208. When the first insulation fault condition is that there is a distribution line with a number of insulation faults greater than or equal to a preset second number threshold within a preset second time period, outputting a second line operation and maintenance strategy, the second line operation and maintenance strategy including a recommendation to strengthen line inspections and perform line channel clearing; the preset first time period is less than the preset second time period, and the preset second number threshold is greater than the preset first number threshold;

[0109] 209. When the first insulation fault situation is that there is a distribution line in which the number of insulation faults within a preset third time period is greater than or equal to a preset third number threshold, a third line operation and maintenance strategy is output, and the third line operation and maintenance strategy includes a recommendation to perform insulation treatment on the line conductors; the preset second time period is less than the preset third time period, and the preset third number threshold is greater than the preset second number threshold.

[0110] It should be noted that steps 207-209 are the output of the line operation and maintenance strategy under different first insulation fault conditions after statistical analysis of the first insulation state, wherein the preset first duration, the preset second duration, and the preset third duration increase in sequence, and the preset first number threshold, the preset second number threshold, and the preset third number threshold also increase in sequence. For example, the preset first duration is 1 week, the preset second duration is 1 month, and the preset third duration is 1 year, the preset first number threshold is 10 times, the preset second number threshold is 50 times, and the preset third number threshold is 50 times. Then, the line insulation fault situation is statistically analyzed, and the operation and maintenance suggestions (operation and maintenance strategy) are given as follows: 1) If a line has more than 10 insulation faults within 1 week, it is recommended to strengthen line patrols and find the fault location; 2) If a line has more than 50 insulation faults within 1 month, it is recommended to strengthen line patrols and clean the line channels. 3) If a line has more than 500 insulation faults within a year, it is recommended to insulate the line conductors.

[0111] The application provides a power distribution system insulation state analysis method, which comprises the following steps: injecting broadband voltage into a power distribution system at different output frequencies; obtaining operation parameters of the power distribution system, wherein the operation parameters at least include line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current and transformer secondary side three-phase broadband current; determining a first insulation state of the power distribution line according to the broadband voltage and the line broadband zero sequence current; and outputting a line operation and maintenance strategy based on the first insulation state. Through the above method, the insulation state of the power distribution line can be monitored online, and operation and maintenance early warning, suggestions and the like can be given, and the insulation state of the power distribution line is monitored in a way, such as dielectric spectrum and dielectric spectrum correlation coefficient, so that the accuracy and reliability of the detection result are further improved, a technical solution is provided for the change from emergency repair to active operation and maintenance of the power distribution system, accurate operation and maintenance of the power distribution system is realized, and the operation and maintenance efficiency, accuracy and power supply reliability are improved.

[0112] Please refer to Figure 3 , Figure 3 for another flowchart of the power distribution system insulation state analysis method in the embodiment of the application; as shown in the method, Figure 3 the method can analyze the power distribution line, and as shown in the method, Figure 3 the method can comprise the following steps:

[0113] 301. Injecting broadband voltage into a power distribution system at different output frequencies;

[0114] 302. Obtaining operation parameters of the power distribution system, wherein the operation parameters at least include line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current and transformer secondary side three-phase broadband current;

[0115] It should be noted that the steps 301 and 302 are similar to the contents of the steps 201 and 202 shown in Figure 2 , to avoid repetition, the contents will not be described here, and the contents of the steps 201 and 202 shown in the foregoing Figure 2 can be referred to.

[0116] 303. Determining whether a line grounding fault exists in the power distribution line according to the size of the line power frequency zero sequence current;

[0117] 304. If the power distribution line has a line grounding fault, determining the fault type and grounding fault state of the power distribution line according to the size of the transformer secondary side power frequency current, wherein the fault type includes phase-to-phase short circuit fault or single-phase short circuit fault;

[0118] It should be noted that the system power frequency three-phase voltage, power frequency zero sequence voltage, line power frequency zero sequence current can be used to determine whether a single-phase grounding fault occurs. Specifically, according to the size of the line power frequency zero sequence current, it is determined whether the distribution line has a line grounding fault. If the distribution line has a line grounding fault, according to the size of the transformer secondary side power frequency current, the fault type and grounding fault state of the distribution line are determined, wherein the fault type includes a phase-to-phase short circuit fault or a single-phase short circuit fault.

[0119] 305, statistical analysis is performed on the grounding fault state of the distribution line to determine the grounding fault condition of the distribution line;

[0120] Further, in the embodiment, the data record can also include the line name, fault time, fault point current of the line where the grounding fault occurs; the line name, single-phase grounding fault frequency, duration, phase-to-phase fault frequency, grounding fault resistance and fault current of each line. Therefore, when outputting the operation and maintenance strategy, the grounding fault condition of the distribution line can be determined by statistical analysis of the grounding fault state of the distribution line, and the operation and maintenance strategy can be output according to the grounding fault condition.

[0121] 306, when the grounding fault condition is that the number of line grounding faults existing within a preset fourth time length is greater than or equal to a preset first number threshold and the duration of each line grounding fault is less than or equal to a preset first time threshold, a fourth line operation and maintenance strategy is output, the fourth line operation and maintenance strategy is that the distribution line has intermittent grounding faults, and it is suggested to clean the line channel;

[0122] 307, when the grounding fault condition is that the number of line grounding faults existing within a preset fourth time length is greater than or equal to a preset first number threshold and the duration of each line grounding fault is less than or equal to a preset second time threshold, a fifth line operation and maintenance strategy is output, the fifth line operation and maintenance strategy is that the distribution line has foreign object contact, and it is suggested to clean and check the line channel; the preset second time threshold is greater than the preset first time threshold;

[0123] 308, when the grounding fault condition is that the number of line grounding faults existing within a preset fourth time length is greater than or equal to a preset first number threshold and the duration of each line grounding fault is less than or equal to a preset third time threshold, a sixth line operation and maintenance strategy is output, the sixth line operation and maintenance strategy is that the distribution line has a persistent single-phase grounding fault, and it is suggested to strengthen the line conductor insulation; the preset third time threshold is greater than the preset second time threshold.

[0124] It should be noted that steps 306-308 are statistical analysis of ground fault state, and the output of line operation strategy under different ground fault conditions, wherein the preset first time threshold, the preset second time threshold and the preset third time threshold increase in turn, for example, the preset fourth time length is one minute, the preset first time threshold is 1s, the preset second time threshold is 1s-10s, and the preset third time threshold is more than 10s, and the preset first number threshold is 3 times or more, then the statistical analysis of the line ground fault condition is carried out, and the operation suggestion is output: 1) if the line occurs 3 times or more single-phase ground fault with duration not more than 1s within 1 minute, it is considered that the line occurs intermittent ground fault, and it is suggested to clean the line channel; 2) if the line appears single-phase ground fault with duration of 1s-10s, it is considered that the line appears foreign object contact, and it is suggested to carry out line channel cleaning, check line insulator, arrester, bird nest, small animal invasion, etc.; 3) if the line appears single-phase ground fault more than 10s, it is considered that the line appears persistent single-phase ground fault, and it is suggested to strengthen the line conductor insulation.

[0125] The application provides a power distribution system insulation state analysis method, which comprises the following steps: injecting broadband voltage into a power distribution system at different output frequencies; obtaining operation parameters of the power distribution system, wherein the operation parameters at least include line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current, and transformer secondary side three-phase broadband current; determining a ground fault state of a power distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current; and outputting a line operation strategy based on the ground fault state. Through the above method, the ground fault state of the power distribution line can be monitored online, and operation early warning, suggestions, etc. are given, which provides a technical solution for the change from emergency maintenance to active operation of the power distribution system, realizes accurate operation of the power distribution system, and improves operation efficiency, accuracy and power supply reliability.

[0126] Please refer to Figure 4 , Figure 4 Another flowchart of the power distribution system insulation state analysis method in the embodiment of the application is shown in Figure 4 The method shown in Figure 4 may comprise the following steps:

[0127] 401, injecting broadband voltage into a power distribution system at different output frequencies;

[0128] 402, obtaining operation parameters of the power distribution system, wherein the operation parameters at least include line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current, and transformer secondary side three-phase broadband current;

[0129] It should be noted that steps 401 and 402 are similar to the contents of steps 101 and 102 shown in FIG. 1, and thus are not described herein again for brevity. For details, reference can be made to the foregoing description of steps 101 and 102. Figure 1 It should be noted that steps 401 and 402 are similar to the contents of steps 101 and 102 shown in FIG. 1, and thus are not described herein again for brevity. For details, reference can be made to the foregoing description of steps 101 and 102. Figure 1 It should be noted that steps 401 and 402 are similar to the contents of steps 101 and 102 shown in FIG. 1, and thus are not described herein again for brevity. For details, reference can be made to the foregoing description of steps 101 and 102.

[0130] 403, when the ratio of the amplitude of the three-phase bus impulse voltage of each bus switch cabinet to the three-phase bus power frequency voltage is greater than or equal to a preset multiple threshold value, and the phase of the three-phase bus impulse voltage of each bus switch cabinet is greater than a preset phase threshold value, it is determined that the second insulation state of the bus is a bus insulation fault, and the preset phase threshold value is set based on the phase of the three-phase bus power frequency voltage of each bus switch cabinet;

[0131] In this embodiment, the second insulation state of the bus is determined by analyzing each bus switch cabinet. Specifically, when the ratio of the amplitude of the three-phase bus impulse voltage of each bus switch cabinet to the three-phase bus power frequency voltage is greater than or equal to a preset multiple threshold value, and the phase of the three-phase bus impulse voltage of each bus switch cabinet is greater than a preset phase threshold value, it is determined that the second insulation state of the bus is a bus insulation fault, and the preset phase threshold value is set based on the phase of the three-phase bus power frequency voltage of each bus switch cabinet. That is, when the amplitude of the three-phase bus impulse voltage of the bus switch cabinet exceeds the preset multiple threshold value of the background threshold value, it is considered that the bus insulation fault occurs in the outgoing line cabinet, indicating a bus insulation fault. For example, if the amplitude of the impulse voltage of each bus switch cabinet exceeds 1.5 times the background threshold value, it is considered that the bus insulation fault occurs in the outgoing line cabinet. The amplitude comparison method is used to determine in which switch cabinet the bus insulation fault occurs.

[0132] For example, the second insulation state can also be determined by detecting whether the amplitude of the impulse voltage of each bus switch cabinet exceeds a threshold value, which is 0.1% to 50% of the system nominal voltage; checking whether the phase of the impulse voltage is within the range of π-π / 4 to π+π / 4 or -π / 4 to π / 4 of the phase power frequency voltage; and if the impulse voltage of a certain line outgoing line cabinet continuously meets the conditions S901 and S902 for 2 to 100 power frequency cycles, it is considered that the bus insulation fault occurs in the outgoing line cabinet.

[0133] 404, statistically analyzing the second insulation state of the bus of the power distribution system to determine the second insulation fault condition of the bus, the second insulation state including a bus insulation fault;

[0134] In this embodiment, the position and occurrence time of the bus insulation fault are also recorded, and thus the bus insulation fault of the second insulation state of the bus of the power distribution system can be statistically analyzed to determine the second insulation fault condition of the bus.

[0135] 405. When the second insulation fault condition is a busbar insulation fault, a busbar operation and maintenance strategy is output, wherein the busbar operation and maintenance strategy includes a suggestion to shut down the power supply to check the fault condition and carry out emergency repairs.

[0136] The present invention provides a method for analyzing the insulation status of a power distribution system, the method comprising: injecting broadband voltage into the power distribution system at different output frequencies; obtaining operating parameters of the power distribution system, the operating parameters at least including line power frequency zero-sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero-sequence current, transformer secondary side three-phase broadband current; determining the second insulation state of the bus based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage; and outputting a bus operation and maintenance strategy based on the second insulation state. The above method can monitor the insulation state of the bus online, and provide operation and maintenance warnings and suggestions, etc., providing a technical solution for the transformation of the power distribution system from emergency maintenance to active operation and maintenance, realizing precise operation and maintenance of the power distribution system, and improving operation and maintenance efficiency, accuracy and power supply reliability.

[0137] See also Figure 5 , Figure 5 FIG. 2 is a flow chart of a method for analyzing insulation status of a power distribution system according to an embodiment of the present invention; FIG. Figure 5 The method shown is an analysis of the transformer, such as Figure 5 The illustrated method may include:

[0138] 501. Injecting broadband voltage into the power distribution system at different output frequencies;

[0139] 502. Obtain operating parameters of the power distribution system, wherein the operating parameters include at least line power frequency zero-sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero-sequence current, and transformer secondary side three-phase broadband current;

[0140] It should be noted that steps 401 and 402 are Figure 1 The contents of steps 101 and 102 are similar, and are not described here to avoid repetition. For details, please refer to the aforementioned Figure 1 The contents of steps 101 and 102 are shown.

[0141] 503. Determine a second angle difference between the broadband voltage at different frequencies and the broadband current on the secondary side of the transformer for each phase of the transformer using the broadband current on the secondary side of the transformer and the broadband voltage at different frequencies.

[0142] 504. Determine a second dielectric spectrum of each phase of the transformer at different frequencies using the second angle difference and tangent value algorithm;

[0143] For example, steps 501-504 can be implemented as follows: step 501, coupling a sinusoidal voltage with frequency n and amplitude m to the three phases of the first side winding of the transformer; step 502, obtaining the three-phase current of the second side winding of the transformer; step 503, calculating the phase difference between the three-phase current of the second side winding of the transformer and the sinusoidal voltage with frequency n; step 504, calculating the cotangent of the phase difference between the current and the voltage as the three-phase dielectric loss value of the first side winding to the second side winding of the transformer with frequency n; changing the frequency of the output sinusoidal voltage step by step with step size s, and keeping the amplitude m, and repeating steps 501-504 to obtain the third dielectric spectrum of the three-phase first side winding to the second side winding of the transformer from 0.1 Hz to 1 MHz.

[0144] 505. determining the third insulation state of the low-voltage winding of the transformer according to the second dielectric spectrum of each phase of the transformer at each output frequency.

[0145] It can be understood that the second dielectric spectrum is obtained based on the change of dielectric loss with output frequency, and therefore, the third insulation state of the low-voltage winding of the transformer can be determined according to the second dielectric spectrum of each phase of the transformer at each output frequency.

[0146] For example, step 505 can include B1-B2:

[0147] B1, determining the first transformer reference dielectric spectrum of each phase of the transformer at different output frequencies when the power distribution system is in normal operation;

[0148] B2, if the second dielectric spectrum of the same phase is greater than the first transformer reference dielectric spectrum at the same output frequency, determining that the third insulation state of the low-voltage winding of the transformer is an insulation fault of the low-voltage winding of the transformer.

[0149] For example, the dielectric spectrum of the low-voltage winding of the transformer at output frequencies from 0.1 Hz to 1 MHz under normal state (e.g., when the transformer is in operation) is calculated as the first transformer reference dielectric spectrum (reference dielectric spectrum) of each phase. The third insulation state of the low-voltage winding of the transformer can be determined by comparing the second dielectric spectrum of the same phase with the first transformer reference dielectric spectrum at the same output frequency. Specifically, if the second dielectric spectrum of the same phase is greater than the first transformer reference dielectric spectrum at the same output frequency, it is determined that the third insulation state of the low-voltage winding of the transformer is an insulation fault of the low-voltage winding of the transformer; if the second dielectric spectrum of the same phase is equal to the first transformer reference dielectric spectrum at the same output frequency, it is determined that the third insulation state of the low-voltage winding of the transformer is normal insulation of the low-voltage winding of the transformer.

[0150] In an implementation, the insulation state of the transformer can also be determined by the correlation coefficient of the dielectric spectrum, wherein the transformer comprises a primary side and a secondary side, the primary side comprises a high-voltage winding side or a medium-voltage winding side, and the secondary side comprises a low-voltage winding side or a medium-voltage winding side, further, the wideband voltage is injected from the primary side, and the third insulation state of the low-voltage winding of the transformer is determined based on the wideband current and the wideband voltage of the three-phase wideband current of the secondary side of the transformer, and the method further comprises:

[0151] C1, determining the third angle difference between the wideband voltage of the secondary side at different frequencies and the wideband current of the secondary side of the transformer by using the wideband current of the secondary side of the transformer and the wideband voltage at different frequencies;

[0152] C2, determining the third dielectric spectrum between each phase of the secondary side and the primary side of the transformer at different frequencies by using the third angle difference and the tangent value algorithm;

[0153] Further, steps 501-504 can refer to the following examples: the frequency n and amplitude m sinusoidal voltage is coupled to the x phase of the primary transformer first side winding through step 501, the current of the x phase of the secondary side winding of the main transformer is obtained through step 502, further, the phase difference between the frequency n current of the x phase of the main transformer second side and the output frequency n sinusoidal voltage (wideband voltage) is calculated by step C1, the residual angle of the above current and voltage phase difference is calculated by step C2, and the tangent value of the residual angle is taken as the dielectric loss value of the x phase of the main transformer first side to the second side winding at frequency n; the frequency of the output sinusoidal voltage is changed by step s, and the amplitude is kept as m, and steps 502, C1 and C2 are executed in a loop to obtain the dielectric spectrum of the x phase of the main transformer first side to the second side winding from 0.1 Hz to 1 MHz; the steps 501, 502, C1 and C2 are performed on the other two phases to obtain the third dielectric spectrum of the three-phase first side to the second side winding of the main transformer from 0.1 Hz to 1 MHz. The exemplary third dielectric spectrum of the first side to the second side winding includes the third dielectric spectrum of the low-voltage winding to the medium-voltage winding, the third dielectric spectrum of the low-voltage winding to the high-voltage winding, and the third dielectric spectrum of the medium-voltage winding to the high-voltage winding.

[0154] C3, determining the second transformer reference dielectric spectrum between each phase of the secondary side and the primary side at different output frequencies when the power distribution system is in normal operation;

[0155] Exemplarily, the 0.1 Hz-1 MHz dielectric spectrum of the low-voltage winding to the medium-voltage winding, the low-voltage winding to the high-voltage winding, and the medium-voltage winding to the high-voltage winding of the main transformer is obtained by cyclically executing 502, C1 and C2 when the power distribution system is in normal operation (such as when the main transformer is in operation), which is taken as the reference dielectric spectrum (the second transformer reference dielectric spectrum) of the low-voltage winding to the medium-voltage winding, the low-voltage winding to the high-voltage winding, and the medium-voltage winding to the high-voltage winding, respectively.

[0156] C4, determining transformer dielectric spectrum correlation coefficients between each phase of the secondary side and the primary side of the transformer according to the third dielectric spectrum under each output frequency and the second transformer reference dielectric spectrum, the transformer dielectric spectrum correlation coefficients being based on curves of the third dielectric spectrum of the same phase of the secondary side and the primary side varying with different output frequencies and curves of the second transformer reference dielectric spectrum varying with different output frequencies;

[0157] Further, similarity coefficients of 0.1 Hz-1 MHz dielectric spectrum of the low-voltage winding pair to the medium-voltage winding, the low-voltage winding pair to the high-voltage winding, and the medium-voltage winding pair to the high-voltage winding are respectively calculated. That is, transformer dielectric spectrum correlation coefficients between each phase of the secondary side and the primary side of the transformer are determined according to the third dielectric spectrum of each phase of the low-voltage winding pair to the medium-voltage winding under each output frequency and the second transformer reference dielectric spectrum of each phase of the low-voltage winding pair to the medium-voltage winding, transformer dielectric spectrum correlation coefficients between each phase of the secondary side and the primary side of the transformer are determined according to the third dielectric spectrum of each phase of the low-voltage winding pair to the high-voltage winding under each output frequency and the second transformer reference dielectric spectrum of each phase of the low-voltage winding pair to the high-voltage winding, and transformer dielectric spectrum correlation coefficients between each phase of the secondary side and the primary side of the transformer are determined according to the third dielectric spectrum of each phase of the medium-voltage winding pair to the high-voltage winding under each output frequency and the second transformer reference dielectric spectrum of each phase of the medium-voltage winding pair to the high-voltage winding, and it needs to be noted that the transformer dielectric spectrum correlation coefficients also need to be calculated with the same phase dielectric spectrum.

[0158] It needs to be noted that the calculation method of the similarity coefficient can also refer to the above line dielectric spectrum correlation coefficient, and the formula r xy x can also represent the third dielectric spectrum of each phase of the transformer, y represents the reference dielectric spectrum of each phase, the transformer dielectric spectrum correlation coefficient is used to represent the correlation degree of the curve of the third dielectric spectrum varying with different output frequencies and the curve of the reference dielectric spectrum varying with different output frequencies, if the two curves are completely correlated, the correlation coefficient is 1, and if they are completely unrelated, the correlation coefficient is 0.

[0159] C5, if the transformer dielectric spectrum correlation coefficient of any phase is less than a second preset correlation coefficient threshold, it is determined that the third insulation state of the low-voltage winding of the transformer is a transformer low-voltage winding insulation fault.

[0160] For example, the second preset correlation coefficient threshold can be 0.5, if the transformer dielectric spectrum correlation coefficient is less than 0.5, it is considered that the transformer has an insulation fault, and if the transformer dielectric spectrum correlation coefficient is greater than or equal to 0.5, it is considered that the transformer has normal insulation.

[0161] 506、When the third insulation state of the transformer is a transformer low-voltage winding insulation fault, a transformer operation and maintenance strategy is output, and the transformer operation and maintenance strategy includes a suggestion to shut down power for transformer maintenance.

[0162] Further, when the third insulation state of the transformer is a transformer low-voltage winding insulation fault, the transformer operation and maintenance strategy can be output as a suggestion to shut down power for transformer maintenance.

[0163] It should be noted that the above operation and maintenance strategy can be configured with an output priority according to the influence of each operation and maintenance strategy on the current operation state of the power distribution system, the operation and maintenance strategy is output according to the output priority, or the priority order is directly set from the operation and maintenance operation suggested by the operation and maintenance strategy, which is not limited herein, so as to realize the priority reminding and processing of the emergency fault.

[0164] The present application provides a kind of insulation state analysis method of power distribution system, which comprises: different output frequency is injected into power distribution system with wideband voltage;Obtain the operating parameter of power distribution system, operating parameter at least includes line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line wideband zero sequence current, transformer secondary side three-phase wideband current;Based on transformer secondary side three-phase wideband current and wideband voltage, the third insulation state of transformer low-voltage winding is determined;Based on the third insulation state, output transformer operation and maintenance strategy.Through the above method, the insulation state of transformer can be monitored online, and operation and maintenance early warning, suggestion, etc.are given, and by judging the insulation state of transformer through transformer each phase dielectric spectrum and dielectric spectrum correlation coefficient, the accuracy of detection can be improved, which provides a technical solution for the change from emergency maintenance to active operation and maintenance of power distribution system, realizes accurate operation and maintenance of power distribution system, and improves operation and maintenance efficiency, accuracy and power supply reliability.

[0165] In summary, the advantages of the present application are as follows: (1) complete online monitoring of system insulation is realized, with strong timeliness; (2) the monitoring range covers the main equipment of the power distribution system: main transformer, switch cabinet, line, for comprehensive insulation online monitoring, with wide monitoring range; (3) high sensitivity, early insulation hidden trouble of main transformer and line is found early and treated early, which can effectively avoid the development of insulation hidden trouble into major fault; (4) comprehensive operation and maintenance suggestions are provided, which breaks the current "emergency maintenance" status of power distribution system, realizes accurate and efficient operation and maintenance of power distribution system, improves the reliability and safety of power distribution system, and effectively reduces the operation and maintenance cost of the system.

[0166] Please refer to Figure 6 , Figure 6 The structure block diagram of a power distribution system insulation state analysis system in an embodiment of the present application is shown in Figure 6 The power distribution system insulation state analysis system comprises:

[0167] The signal injection module 601 is configured to inject a broadband voltage into the power distribution system at different output frequencies.

[0168] The parameter monitoring module 602 is configured to acquire operation parameters of the power distribution system, wherein the operation parameters at least include a line power frequency zero sequence current, a transformer secondary side power frequency current, a three-phase bus power frequency voltage, a three-phase bus pulse voltage, a line broadband zero sequence current, and a transformer secondary side three-phase broadband current.

[0169] The line analysis module 603 is configured to determine a first insulation state of a power distribution line according to the broadband voltage and the line broadband zero sequence current, and determine a grounding fault state of the power distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current.

[0170] The bus analysis module 604 is configured to determine a second insulation state of a bus according to the three-phase bus pulse voltage and the three-phase bus power frequency voltage.

[0171] The transformer analysis module 605 is configured to determine a third insulation state of a transformer low-voltage winding according to the transformer secondary side three-phase broadband current and the broadband voltage.

[0172] The operation and maintenance strategy output module 606 is configured to output a line operation and maintenance strategy, a bus operation and maintenance strategy, and a transformer operation and maintenance strategy based on the first insulation state, the grounding fault state, the second insulation state, and the third insulation state.

[0173] The application provides a power distribution system insulation state analysis system, which comprises a signal injection module, a parameter monitoring module, a line analysis module, a bus analysis module, a transformer analysis module and an operation and maintenance strategy output module.

[0174] Figure 7 An internal structure diagram of a computer device in an embodiment is shown. The computer device can be a terminal or a server. As shown in the figure, Figure 7 The computer device comprises a processor, a memory and a network interface connected through a system bus. The memory comprises a non-volatile storage medium and an internal memory. The non-volatile storage medium of the computer device stores an operating system and can also store a computer program, which, when executed by the processor, can enable the processor to implement the above method. The internal memory can also store a computer program, which, when executed by the processor, can enable the processor to execute the above method. Those skilled in the art can understand that Figure 7 The structure shown in the figure is only a block diagram of part of the structure related to the scheme of the present application and does not constitute a limitation on the computer device to which the scheme of the present application is applied. A specific computer device can comprise more or fewer components than those shown in the figure, or some components can be combined or have a different arrangement of components.

[0175] In one embodiment, a computer device is provided, comprising a memory and a processor, the memory storing a computer program, the computer program being executed by the processor to enable the processor to execute the method as Figure 1 , Figure 2 , Figure 3, Figure 4 and Figure 5 the steps of the method shown in

[0176] In one embodiment, a computer readable storage medium is provided, storing a computer program, which, when executed by a processor, causes the processor to perform the steps of the method shown in Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 the steps of the method shown in

[0177] It is understood by those of ordinary skill in the art that all or part of the processes in the above-mentioned embodiments can be implemented by a computer program instructing relevant hardware, and the program can be stored in a non-volatile computer readable storage medium. When the program is executed, it can include the processes of the above-mentioned embodiments. Any reference to memory, storage, database or other medium used in the embodiments provided by the present application can include non-volatile and / or volatile memory. Non-volatile memory can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM) or flash memory. Volatile memory can include random access memory (RAM) or external cache memory. As an illustration but not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link (Synchlink) DRAM (SLDRAM), memory bus (Rambus) direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM), etc.

[0178] Any combination of the technical features of the above embodiments can be made. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, however, as long as the combination of the technical features does not exist, it should be considered as the scope of the present application.

[0179] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application. Therefore, the scope of protection of the patent of the present application should be subject to the appended claims.

Claims

1. A method of analyzing an insulation condition of a power distribution system, characterized by, The method comprises: injecting a wide-frequency voltage into a power distribution system at different output frequencies; obtaining operating parameters of the power distribution system, the operating parameters at least including line power-frequency zero-sequence current, transformer secondary-side power-frequency current, three-phase bus power-frequency voltage, three-phase bus pulse voltage, line wide-frequency zero-sequence current, transformer secondary-side three-phase wide-frequency current; determining a first insulation state of a power distribution line according to the wide-frequency voltage and the line wide-frequency zero-sequence current; determining a ground fault state of the power distribution line according to the line power-frequency zero-sequence current and the transformer secondary-side power-frequency current; determining a second insulation state of a bus according to the three-phase bus pulse voltage and the three-phase bus power-frequency voltage; determining a third insulation state of a transformer low-voltage winding according to the transformer secondary-side three-phase wide-frequency current and the wide-frequency voltage; outputting a line operation and maintenance strategy, a bus operation and maintenance strategy, and a transformer operation and maintenance strategy based on the first insulation state, the ground fault state, the second insulation state, and the third insulation state; wherein the determining of the first insulation state of the power distribution line according to the wide-frequency voltage and the line wide-frequency zero-sequence current comprises: determining a first angle difference between the line wide-frequency zero-sequence current and the wide-frequency voltage of each line at different output frequencies according to the wide-frequency voltage and the line wide-frequency zero-sequence current at different output frequencies; determining a first dielectric spectrum of each power distribution line at different output frequencies by using the first angle difference and a tangent value algorithm; when there is a power distribution line in which the first dielectric spectrum at the current time is greater than the first dielectric spectrum at the last time at the same output frequency, determining that the first insulation state of the power distribution line is a line insulation fault; wherein the determining of the ground fault state of the power distribution line according to the line power-frequency zero-sequence current and the transformer secondary-side power-frequency current comprises: determining whether there is a line ground fault of the power distribution line according to the size of the line power-frequency zero-sequence current; if there is a line ground fault of the power distribution line, determining a fault type and a ground fault state of the power distribution line according to the size of the transformer secondary-side power-frequency current, the fault type including an inter-phase short-circuit fault or a single-phase short-circuit fault; wherein the determining of the second insulation state of the bus according to the three-phase bus pulse voltage and the three-phase bus power-frequency voltage comprises: when the ratio of the amplitude of the three-phase bus pulse voltage of each bus switch cabinet to the three-phase bus power-frequency voltage is greater than or equal to a preset multiple threshold value, and the phase of the three-phase bus pulse voltage of each bus switch cabinet is greater than a preset phase threshold value, determining that the second insulation state of the bus is a bus insulation fault, the preset phase threshold value being set based on the phase of the three-phase bus power-frequency voltage of each bus switch cabinet; wherein the determining of the third insulation state of the transformer low-voltage winding according to the transformer secondary-side three-phase wide-frequency current and the wide-frequency voltage comprises: determining a second angle difference between the wide-frequency voltage and the transformer secondary-side wide-frequency current of each phase of the transformer at different frequencies by using the transformer secondary-side wide-frequency current and the wide-frequency voltage at different frequencies; determining a second dielectric spectrum of each phase of the transformer at different frequencies by using the second angle difference and a tangent value algorithm; According to the second dielectric spectrum of each phase of the transformer under each output frequency, a third insulation state of the low-voltage winding of the transformer is determined.

2. The method of claim 1, wherein, The third insulation state of the low-voltage winding of the transformer is determined according to the second dielectric spectrum of each phase of the transformer under each output frequency, including: A first transformer reference dielectric spectrum of each phase of the transformer under different output frequencies when the power distribution system is in normal operation is determined. If the second dielectric spectrum of the same phase under the same output frequency is greater than the first transformer reference dielectric spectrum, it is determined that the third insulation state of the low-voltage winding of the transformer is a transformer low-voltage winding insulation fault.

3. The method of claim 1, wherein, The first dielectric spectrum of each power distribution line under different output frequencies is determined by using the first angle difference and the tangent value algorithm, and then further including: A line reference dielectric spectrum under different output frequencies when the power distribution system is in normal operation is determined. A line dielectric spectrum correlation coefficient is determined by using the first dielectric spectrum of each power distribution line under different output frequencies and the line reference dielectric spectrum, the line dielectric spectrum correlation coefficient being obtained based on the curve of the first dielectric spectrum changing with different output frequencies and the curve of the line reference dielectric spectrum changing with different output frequencies. If any of the line dielectric spectrum correlation coefficients is less than a first preset correlation coefficient threshold, it is determined that the first insulation state of the power distribution line is a line insulation fault.

4. The method of claim 1, wherein, The transformer includes a primary side and a secondary side, the primary side includes a high-voltage winding side or a medium-voltage winding side, the secondary side includes a low-voltage winding side or a medium-voltage winding side, and the wide-frequency voltage is injected from the primary side, and the third insulation state of the low-voltage winding of the transformer is determined based on the wide-frequency current of the secondary side of the transformer and the wide-frequency voltage, further including: A third angle difference between the wide-frequency voltage of the secondary side and the wide-frequency current of the secondary side of the transformer under different frequencies is determined by using the wide-frequency current of the secondary side of the transformer and the wide-frequency voltage under different frequencies. A third dielectric spectrum between each phase of the secondary side and the primary side of the transformer under different frequencies is determined by using the third angle difference and the tangent value algorithm. A second transformer reference dielectric spectrum between each phase of the secondary side and the primary side of the transformer under different output frequencies when the power distribution system is in normal operation is determined. A transformer dielectric spectrum correlation coefficient between each phase of the secondary side and the primary side of the transformer is determined according to the third dielectric spectrum under each output frequency and the second transformer reference dielectric spectrum, the transformer dielectric spectrum correlation coefficient being obtained based on the curve of the third dielectric spectrum of the same phase of the secondary side and the primary side changing with different output frequencies and the curve of the second transformer reference dielectric spectrum changing with different output frequencies. If any of the transformer dielectric spectrum correlation coefficients is less than a second preset correlation coefficient threshold, it is determined that the third insulation state of the low-voltage winding of the transformer is a transformer low-voltage winding insulation fault.

5. The method of claim 1, wherein, Based on the first insulation state, a line operation and maintenance strategy is output, including: A statistical analysis of the first insulation state of the power distribution line is performed to determine the first insulation fault condition of the power distribution line, and the first insulation state includes a line insulation fault. When the first insulation fault condition is that there is a power distribution line with an insulation fault number within a preset first time length greater than or equal to a preset first number threshold, a first line operation and maintenance strategy is output, the first line operation and maintenance strategy including recommending strengthening line patrol and finding fault position; When the first insulation fault condition is that there is a power distribution line with an insulation fault number within a preset second time length greater than or equal to a preset second number threshold, a second line operation and maintenance strategy is output, the second line operation and maintenance strategy including recommending strengthening line patrol and performing line channel cleaning; the preset first time length is less than the preset second time length, and the preset second number threshold is greater than the preset first number threshold; When the first insulation fault condition is that there is a power distribution line with an insulation fault number within a preset third time length greater than or equal to a preset third number threshold, a third line operation and maintenance strategy is output, the third line operation and maintenance strategy including recommending performing line conductor insulation treatment; the preset second time length is less than the preset third time length, and the preset third number threshold is greater than the preset second number threshold.

6. The method of claim 1, wherein, Based on the second insulation state, a bus operation and maintenance strategy is output, including: statistically analyzing a second insulation state of a bus of the power distribution system to determine a second insulation fault condition of the bus, the second insulation state including bus insulation fault; When the second insulation fault condition is that there is a bus insulation fault, a bus operation and maintenance strategy is output, the bus operation and maintenance strategy including recommending power-off to check fault condition for repair.

7. The method of claim 1, wherein, Based on the third insulation state, a transformer operation and maintenance strategy is output, including: When the third insulation state of the transformer is transformer low-voltage winding insulation fault, a transformer operation and maintenance strategy is output, the transformer operation and maintenance strategy including recommending power-off for transformer maintenance.

8. The method of claim 1, wherein, Based on the grounding fault state, a line operation and maintenance strategy is output, including: statistically analyzing a grounding fault state of the power distribution line to determine a grounding fault condition of the power distribution line; When the grounding fault condition is that there is a power distribution line with a line grounding fault number within a preset fourth time length greater than or equal to a preset first number threshold and a duration of each line grounding fault less than or equal to a preset first time threshold, a fourth line operation and maintenance strategy is output, the fourth line operation and maintenance strategy being that the power distribution line has intermittent grounding fault and recommending line channel cleaning; When the grounding fault condition is that there is a power distribution line with a line grounding fault number within a preset fourth time length greater than or equal to a preset first number threshold and a duration of each line grounding fault less than or equal to a preset second time threshold, a fifth line operation and maintenance strategy is output, the fifth line operation and maintenance strategy being that the power distribution line has foreign matter contact, and recommending line channel cleaning and inspection; the preset second time threshold is greater than the preset first time threshold. When the ground fault condition is a distribution line in which the number of line ground faults existing within a preset fourth time length is greater than or equal to a preset first number threshold and the duration of each line ground fault is less than or equal to a preset third time threshold, a sixth line operation and maintenance strategy is output, the sixth line operation and maintenance strategy is that the distribution line has a line persistent single-phase ground fault, and it is recommended to strengthen the line conductor insulation; the preset third time threshold is greater than the preset second time threshold.

9. An electrical distribution system insulation condition analysis system characterized by, The power distribution system insulation state analysis system comprises: a signal injection module configured to inject broadband voltage into the power distribution system at different output frequencies; a parameter monitoring module configured to obtain operating parameters of the power distribution system, the operating parameters comprising at least line power frequency zero sequence current, transformer secondary side power frequency current, three-phase bus power frequency voltage, three-phase bus pulse voltage, line broadband zero sequence current, and transformer secondary side three-phase broadband current; a line analysis module configured to determine a first insulation state of a distribution line according to the broadband voltage and the line broadband zero sequence current, and determine a ground fault state of the distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current; a bus analysis module configured to determine a second insulation state of a bus based on the three-phase bus pulse voltage and the three-phase bus power frequency voltage; a transformer analysis module configured to determine a third insulation state of a transformer low-voltage winding based on the transformer secondary side three-phase broadband current and the broadband voltage; an operation and maintenance strategy output module configured to output line operation and maintenance strategies, bus operation and maintenance strategies, and transformer operation and maintenance strategies based on the first insulation state, the ground fault state, the second insulation state, and the third insulation state; wherein the line analysis module is specifically configured to determine a first angle difference between the line broadband zero sequence current and the broadband voltage of each line at different output frequencies according to the broadband voltage and the line broadband zero sequence current at different output frequencies, determine a first dielectric spectrum of each distribution line at different output frequencies by using the first angle difference and a tangent value algorithm, and determine that the first insulation state of the distribution line is a line insulation fault when there is a distribution line in which the first dielectric spectrum at the current time is greater than the first dielectric spectrum at the previous time at the same output frequency. wherein the determination of the ground fault state of the distribution line according to the line power frequency zero sequence current and the transformer secondary side power frequency current comprises: determining whether the distribution line has a line ground fault according to the size of the line power frequency zero sequence current; and if the distribution line has a line ground fault, determining the fault type and the ground fault state of the distribution line according to the size of the transformer secondary side power frequency current, the fault type comprising an inter-phase short-circuit fault or a single-phase short-circuit fault. The bus analysis module is specifically configured to: when a ratio of an amplitude of a three-phase bus impulse voltage of each bus switch cabinet to a three-phase bus power frequency voltage is greater than or equal to a preset multiple threshold, and a phase of the three-phase bus impulse voltage of each bus switch cabinet is greater than a preset phase threshold, determine that a second insulation state of the bus is a bus insulation fault, and the preset phase threshold is set based on a phase of the three-phase bus power frequency voltage of each bus switch cabinet. The transformer analysis module is specifically configured to: determine a second angle difference between the wide-frequency voltage at different frequencies and the transformer secondary side wide-frequency current of each phase of the transformer by using the transformer secondary side wide-frequency current and the wide-frequency voltage at different frequencies; determine a second dielectric spectrum of each phase of the transformer at different frequencies by using the second angle difference and a tangent value algorithm; and determine a third insulation state of a low-voltage winding of the transformer according to the second dielectric spectrum of each phase of the transformer at each output frequency.

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