A method and system for locating harmonic sources in a proactive power distribution network

Abstract

The present application relates to the technical field of electric variable detection, and in particular to a kind of active distribution network harmonic source positioning method and system, method includes: determining the probability characteristics of each substation in the current monitoring time period, in combination with the harmonic impedance attenuation characteristics of each substation, total harmonic current increment of substation is divided, the dynamic responsibility current distribution of each substation is obtained, in combination with historical harmonic responsibility index stock, obtain the latest harmonic responsibility index stock of each substation in the current monitoring time period, thereby screening substation, and the latest harmonic responsibility index stock and fundamental current effective value of target substation are fused, to obtain the electric-thermal comprehensive characteristic load of target substation, and then obtain the transformer insulation deterioration risk index of target substation, finally by transformer insulation deterioration risk index, the accurate positioning of distribution network harmonic source is realized, and the operation safety and operation efficiency of distribution network are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of electrical variable detection technology, specifically to a method and system for locating harmonic sources in an active distribution network. Background Technology

[0002] With the large-scale integration of nonlinear devices such as distributed photovoltaic power and electric vehicle charging stations into the power distribution network, continuous steady-state high-frequency harmonic currents are generated in the grid. These high-frequency harmonics induce significant skin and proximity effects in the windings of distribution transformers, leading to a surge in internal heat generation, which in turn accelerates the aging of insulating paper materials and poses a risk of equipment burnout. Therefore, online identification of the steady-state harmonic sources causing long-term accumulated heat in transformers is crucial for timely issuance of load reduction intervention work orders.

[0003] Existing methods for locating harmonic sources in distribution networks typically involve obtaining the harmonic components in the current of each transformer substation downstream of the substation, and then locating the harmonic source based on the amplitude of these components. However, this method has significant drawbacks: firstly, it cannot distinguish whether a transformer substation actively emits or passively absorbs harmonics, easily leading to misjudgments; secondly, it only focuses on the magnitude of the harmonic current, ignoring the contribution of the fundamental load current to the transformer's thermal effect, resulting in an inability to accurately assess the actual impact of harmonic sources on transformer insulation degradation and hindering effective preventative control. Summary of the Invention

[0004] To address the technical problem that existing methods for locating harmonic sources in distribution networks cannot accurately pinpoint these sources, the present invention aims to provide an active method and system for locating harmonic sources in distribution networks. The specific technical solution adopted is as follows: In a first aspect of the present invention, a method for locating harmonic sources in an active distribution network is provided, comprising: Determine the probability characteristics of harmonic generation in each transformer area during the current monitoring period; Based on the harmonic generation probability characteristics and harmonic impedance attenuation characteristics of each transformer area, the total harmonic current increment of the substation is divided to obtain the dynamic responsibility current allocation of each transformer area. Based on the dynamic responsibility current allocation of each transformer area and the historical harmonic responsibility index inventory of the previous adjacent monitoring time period, the latest harmonic responsibility index inventory of each transformer area in the current monitoring time period is obtained. The target distribution area is obtained by integrating the latest harmonic responsibility index inventory and the fundamental current RMS value; the target distribution area is selected from the latest harmonic responsibility index inventory. Based on the comprehensive electrothermal load characteristics, the transformer insulation degradation risk index for the target distribution area is obtained; The transformer insulation degradation risk index is used to locate harmonic sources in the distribution network.

[0005] In an exemplary embodiment, the process of obtaining the harmonic generation probability characteristics of the transformer area includes: Based on the proportion of nonlinear equipment capacity in the transformer substation during the current monitoring period, the apparent power fluctuation in the transformer substation during the current monitoring period, and the rated capacity of the transformer in the transformer substation, the harmonic generation probability characteristics of the transformer substation during the current monitoring period are obtained. The harmonic generation probability characteristics of the transformer substation are positively correlated with the proportion of nonlinear equipment capacity and the apparent power fluctuation, and negatively correlated with the rated capacity of the transformer.

[0006] In an exemplary embodiment, the process of obtaining the dynamic responsibility current allocation includes: The harmonic impedance attenuation characteristics of the transformer substation are obtained based on the actual line length between the transformer substation and the substation; the harmonic impedance attenuation characteristics are inversely correlated with the actual line length. Based on the harmonic impedance attenuation characteristics and harmonic generation probability characteristics of the transformer area, the harmonic responsibility allocation ratio of the transformer area is obtained; the harmonic responsibility allocation ratio is positively correlated with both the harmonic impedance attenuation characteristics and the harmonic generation probability characteristics of the transformer area. The dynamic responsibility current allocation of each transformer area is obtained based on the harmonic responsibility allocation ratio of each transformer area and the total harmonic current increment of the substation.

[0007] In an exemplary embodiment, obtaining the dynamic responsibility current allocation for each transformer substation based on the harmonic responsibility allocation ratio of each substation and the total harmonic current increment of the substation includes: Determine whether the total harmonic current increment of the substation is greater than or equal to 0; When the total harmonic current increment of the substation is greater than or equal to 0, the product of the harmonic responsibility allocation ratio of each distribution area and the total harmonic current increment of the substation is calculated to obtain the dynamic responsibility current allocation of each distribution area. When the total harmonic current increment of the substation is less than 0, determine the stock ratio of the historical harmonic responsibility index of each distribution area in the previous monitoring period; calculate the product of the stock ratio of each distribution area and the total harmonic current increment of the substation to obtain the dynamic responsibility current allocation of each distribution area.

[0008] In an exemplary embodiment, the process of obtaining the latest harmonic responsibility index inventory includes: The latest harmonic responsibility index is obtained by summing the historical harmonic responsibility index inventory and the dynamic responsibility current allocation.

[0009] In an exemplary embodiment, the process of acquiring the target station area includes: Compare the latest harmonic responsibility index inventory of each transformer area with the preset inventory threshold; The transformer area corresponding to the latest harmonic responsibility index inventory that is greater than the preset inventory threshold is determined as the target transformer area.

[0010] In an exemplary embodiment, the process of obtaining the electrothermal composite characteristic load includes: The weighted value of the latest harmonic responsibility index is obtained by combining the latest harmonic responsibility index inventory of the target transformer area with the preset harmonic heating weighting coefficient. The L2 norm of the weighted value and the effective value of the fundamental current is calculated to obtain the comprehensive electrothermal characteristic load.

[0011] In an exemplary embodiment, the process of obtaining the transformer insulation degradation risk index includes: Obtain the rated current and rated winding hot spot temperature rise constant of the transformer in the target distribution area; The rated current, rated winding hot spot temperature rise constant, and the electrothermal comprehensive characteristic load are input into the preset winding temperature rise calculation formula, and the estimated value of the transformer winding hot spot temperature of the target area is output. The estimated value of the transformer winding hot spot temperature is input into the transformer insulation aging calculation model based on the Arrhenius rule, and the transformer insulation deterioration risk index is output.

[0012] In an exemplary embodiment, the step of locating the harmonic source of the distribution network using the transformer insulation degradation risk index includes: Compare the transformer insulation degradation risk index of each target distribution area with the preset risk threshold. The location of the target transformer area corresponding to the transformer insulation degradation risk index that is greater than the preset risk threshold is determined, thereby realizing the location of the harmonic source in the distribution network.

[0013] In a second aspect of the present invention, an active distribution network harmonic source location system is provided, comprising: a memory and a processor; the memory is connected to the processor; the memory is used to store program instructions; the processor is used to implement the above-described active distribution network harmonic source location method when the program instructions are executed.

[0014] This invention offers the following advantages: Firstly, it introduces the probability characteristics of harmonic generation in different transformer substations, determining the likelihood of these substations actively generating harmonics, which serves as the basis for subsequent dynamic responsibility allocation. Secondly, considering that harmonics attenuate due to line impedance during propagation in the distribution network, the total harmonic current increment is allocated based on the harmonic impedance attenuation characteristics of each substation, resulting in a dynamic responsibility current allocation. This makes the responsibility current allocation more consistent with the actual physical process, and the dynamic allocation reflects the actual contribution of each substation to the total harmonic increment of the substation in the current period, further improving the accuracy of harmonic source location. Thirdly, it introduces historical data, giving the harmonic responsibility assessment a time-cumulative effect. Because transformer heating and insulation aging are long-term processes, a single harmonic event may have little impact, but the continuously accumulated responsibility index can reflect the substation's long-term impact on transformer heating. The contribution of the effect is considered to avoid misjudgment caused by instantaneous fluctuations, making the positioning results more consistent with the actual scenario of long-term cumulative heat generation. The heat generation caused by harmonics (skin effect, proximity effect) is superimposed on the Joule heat generated by the fundamental current itself. By integrating the stock of harmonic responsibility indicators (reflecting the contribution of harmonic thermal effects) and the effective value of the fundamental current (reflecting the thermal effect of the base load), a comprehensive electrothermal characteristic load is constructed, which directly quantifies the comprehensive impact of the distribution area on the transformer's thermal load, upgrading the harmonic source positioning from electrical quantity positioning to thermal effect positioning. The comprehensive electrothermal characteristic load is further transformed into an insulation degradation risk index, realizing the leap from physical quantity to risk quantity. This index can be directly used to assess the degree of accelerated insulation aging faced by the transformer due to harmonic pollution in the distribution area. The final risk index can achieve accurate positioning of the harmonic source in the distribution network. Attached Figure Description

[0015] Figure 1 This is a flowchart of an active distribution network harmonic source location method provided in one embodiment of the present invention. Detailed Implementation

[0016] To further illustrate the technical means and effects adopted by the present invention to achieve its intended purpose, the specific implementation methods, structures, features, and effects of the present invention are described in detail below with reference to the accompanying drawings and preferred embodiments. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. Furthermore, specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0017] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. All data and information collected in this application have been obtained with full consent.

[0018] This embodiment provides an active method for locating harmonic sources in a distribution network. The applicable network topology includes substations and multiple transformer substations downstream of the substations. The number of transformer substations is set to M (in principle, M is greater than or equal to 2). The specific number M in the network topology is not limited, but is usually quite large. Relevant electrical quantity acquisition devices are installed at the substations and each transformer substation to collect the electrical data required in this embodiment. For example, a high-frequency power quality monitoring terminal is deployed at the substation feeder outlet to obtain the effective value of the total harmonic current, and low-frequency smart meters are installed in each transformer substation to obtain low-frequency data such as apparent power.

[0019] In this embodiment, the station area spatial index number is set to... ,in "I" is a positive integer, ranging from 1 to M, representing the first... The first station area. Any station area is set as the first... The first district, targeting the first The first district, in the... Each distribution area is equipped with a transformer; obtain the rated capacity of the transformer in that distribution area. and the actual line length between the distribution area and the substation. Specifically, this refers to the actual transmission length of the line from the distribution area to the substation feeder outlet. This data can be pre-stored in the distribution network's marketing ledger database and retrieved from it.

[0020] This embodiment aims to locate the steady-state harmonic source (i.e., the transformer substation) that causes long-term cumulative heating in the transformer, rather than capturing transient high-frequency faults in the power grid. Therefore, this embodiment sets a fixed analysis time window, i.e., a monitoring period, and uses this monitoring period to extract the envelope change of the effective value of steady-state harmonics as the data basis for subsequent long-term health assessment. Since the smart meters in each transformer substation upload data information according to a preset sampling period, this embodiment uses the sampling period of the smart meters as the monitoring period. In conventional engineering practice, this sampling period is usually set to 15 minutes. Therefore, this embodiment sets the duration of each monitoring period to 15 minutes. Data is uploaded synchronously from each transformer substation to ensure data alignment in the time dimension. Moreover, the two time boundaries of the monitoring period are the times when data is received from two adjacent transformer substations.

[0021] For any given monitoring time period, taking the current monitoring time period as an example, this embodiment can directly read the effective value of the total harmonic current (THC) of the substation during the current monitoring time period through the high-frequency power quality monitoring terminal at the substation feeder outlet. Alternatively, it can be calculated as follows: Since substation harmonic current is high-frequency data, multiple THC effective values ​​(the effective value of the THC is the square root of the sum of the squares of the various harmonic currents) can be obtained within the current monitoring time period. Then, the average value of all THC effective values ​​within the current monitoring time period is calculated, and the result is taken as the effective value of the substation's THC during the current monitoring time period, denoted as . Frequency reduction is achieved by averaging high-frequency data within the current monitoring period, thus ensuring the alignment of high and low frequency data. The averaging method also filters out millisecond-level transient spikes.

[0022] Using the above method, the effective value of the total harmonic current of the substation in the previous monitoring time period adjacent to the current monitoring time period (hereinafter referred to as the previous monitoring time period) is obtained and denoted as: Then minus This yields the total harmonic current increment of the substation during the current monitoring period. Total harmonic current increment in substation The dimension is A, representing the increment of the total harmonic current in the substation. The value is indicated by a positive or negative sign. If the effective value of the total harmonic current of the substation in the previous monitoring period is greater than the effective value of the total harmonic current of the substation in the current monitoring period, then the increment of the total harmonic current of the substation is indicated by a positive or negative sign. If the value is less than 0, the effective value of the total harmonic current of the substation is decreasing; if the effective value of the total harmonic current of the substation in the previous monitoring period is less than the effective value of the total harmonic current of the substation in the current monitoring period, then the increment of the total harmonic current of the substation is... If the value is greater than 0, the effective value of the total harmonic current of the substation is increasing; if the effective value of the total harmonic current of the substation in the previous monitoring period is equal to the effective value of the total harmonic current of the substation in the current monitoring period, then the increment of the total harmonic current of the substation is... When the value equals 0, the effective value of the total harmonic current in the substation is in a stable trend.

[0023] Moreover, the total harmonic current increment of the substation It is the overall source of harmonic responsibility allocation across the entire network. A value greater than 0 indicates an overall increase in harmonics across the network, requiring additional responsibility for heat generation from downstream transformer substations; a value less than 0 indicates an overall decrease in harmonics across the network, requiring deduction of responsibility for heat generation from downstream transformer substations. Specifically, if determined... If the value is 0, this embodiment can directly skip the calculation of the dynamic responsibility current allocation for the current monitoring period and maintain the historical state of each transformer area in the previous monitoring period to save computing power. If the result is not equal to 0, continue with the subsequent steps.

[0024] For any given area, the first Taking a single distribution area as an example. In this embodiment, to address the lack of historical baselines during initial power-on or network topology changes, it is determined whether the current cycle is the initial power-on commissioning time, or whether the distribution network topology has undergone a change registration (e.g., tie switch switching). If the current cycle is determined to be the initial power-on or a topology change, an initialization operation is forcibly triggered: extracting the first... The total capacity of the nonlinear equipment (nonlinear equipment refers to electrical equipment that generates harmonics and causes distortion of the current waveform during operation, such as frequency converters and charging equipment within the distribution area) that has been registered in each distribution area. (Dimension is kVA), and the th is calculated. The capacity ratio of the total registered nonlinear equipment in each distribution area is used to perform static base allocation for each distribution area. The initial allocation formula is as follows: ; in, Indicates the first Initial harmonic responsibility index for each transformer area (dimension A). This represents the effective value of the total harmonic current collected by the substation in the initial stage; Indicates the first The total capacity of nonlinear equipment registered in each distribution area; Indicates the first The total capacity of nonlinear equipment registered in each substation area, This represents the sum of the total capacity of the nonlinear equipment in all M substations. This represents a preset, extremely small positive number, used as a zero-prevention parameter adjustment factor, and can take values ​​of [value missing]. The dimensions of the denominator must be consistent with those of the denominator to avoid a denominator of 0. Indicates the first The percentage of the total capacity of nonlinear equipment registered in each distribution area.

[0025] As another implementation method, the first The initial harmonic liability index for each transformer substation can also be obtained directly using the following method: This achieves an even distribution of the initial harmonic responsibility indicators for each transformer substation.

[0026] This initial allocation formula ensures that, even in the absence of historical power fluctuation data during startup, areas with larger installed capacities of nonlinear equipment can still be assigned a higher initial heat dissipation responsibility baseline. After initialization, a baseline is established, and the subsequent routine operation process begins with cyclical monitoring.

[0027] like Figure 1 As shown in the figure, the active distribution network harmonic source localization method provided in this embodiment includes the following steps: Step S1: Determine the probability characteristics of harmonic generation in each transformer area during the current monitoring time period; Step S2: Based on the harmonic generation probability characteristics and harmonic impedance attenuation characteristics of each transformer area, divide the total harmonic current increment of the substation to obtain the dynamic responsibility current allocation of each transformer area. Step S3: Based on the dynamic responsibility current allocation of each transformer area and the historical harmonic responsibility index inventory of the previous adjacent monitoring time period, obtain the latest harmonic responsibility index inventory of each transformer area in the current monitoring time period. Step S4: Integrate the latest harmonic responsibility index inventory and fundamental current RMS value of the target transformer area to obtain the comprehensive electrothermal characteristic load of the target transformer area; Step S5: Based on the comprehensive electrothermal load characteristics, obtain the transformer insulation degradation risk index for the target distribution area; Step S6: Locate the harmonic sources in the distribution network using the transformer insulation degradation risk index.

[0028] The following is a detailed explanation of each step.

[0029] Step S1: Determine the probability characteristics of harmonic generation in each transformer area during the current monitoring period.

[0030] According to the The electrical quantity data of each transformer substation within the current monitoring time period is used to obtain the first... The harmonic generation probability characteristics of each transformer substation during the current monitoring time period, the harmonic generation probability characteristics of the substation represent the... The probability of harmonic generation in a given transformer substation during the current monitoring period is as follows: the higher the probability, the higher the value of the harmonic generation probability characteristic of the transformer substation.

[0031] To capture the degree of load fluctuation in each transformer area during the current monitoring period (and thus measure its potential harmonic generation probability), this embodiment extracts low-frequency power data for each transformer area. For the first... The [number] station area, in this embodiment, obtains the [number]th [unit]. The apparent power of each station area during the current monitoring period; the apparent power can be determined by the first... The data is directly obtained and uploaded from the smart meters in each distribution area.

[0032] In an exemplary embodiment, the first... The active and reactive power of each transformer area during the current monitoring period are calculated, and then the first... The square root of the sum of the squares of the active and reactive power of each transformer substation during the current monitoring period is taken as the result of the first... Apparent power of each transformer station during the current monitoring period Similarly, to obtain the first... The apparent power of each station area during the previous monitoring period Then, calculate and absolute value of the difference As the first Apparent power fluctuation of each transformer area during the current monitoring period (in kVA).

[0033] In addition, to prevent the measurement noise of the smart meter itself from being misinterpreted as a real load change while calculating the apparent power fluctuation, this embodiment also obtains the first... The inherent measurement error percentage (e.g., 1%) specified on the factory nameplate of the smart meter for each transformer area is multiplied by the current load level (i.e., the current rated power, in kVA) to output a lower limit of the smart meter measurement error with absolute dimensions (kVA). (Dimensions are in kVA), for example: rated capacity is The area of ​​the platform, Can be calibrated as .Should This will be used as a safety margin value in subsequent probability calculations.

[0034] Get the Total capacity of nonlinear equipment already registered in each distribution area At the same time, obtain the first Rated capacity of transformers in each distribution area The rated capacity of a transformer is the maximum apparent power (in kVA) that the transformer can output under specified environmental conditions during long-term continuous operation. Calculation... and The ratio: The result obtained is used as the first The proportion of nonlinear equipment capacity in each monitoring area during different monitoring time periods Also known as the first The penetration rate of nonlinear equipment in each distribution area. The larger the value of the proportion of nonlinear equipment capacity, the higher the penetration rate of the nonlinear equipment. The higher the proportion of different types and numbers of devices that generate high-frequency distortion within a given distribution area, the better.

[0035] According to the The proportion of nonlinear equipment capacity in each distribution area during the current monitoring period , No. Apparent power fluctuation of each transformer area during the current monitoring period and the The rated capacity of the transformer in each distribution area , obtained the The probability characteristics of harmonic generation in each transformer substation during the current monitoring period. Among them, the first... The proportion of nonlinear equipment capacity in each distribution area during the current monitoring period The larger the value, the higher the value. The higher the proportion of different types and numbers of devices generating high-frequency distortion within a given distribution area, the better. The higher the probability of a transformer substation generating harmonics during the current monitoring period, the higher its harmonic generation probability characteristics; the two are positively correlated. Apparent power fluctuation of each transformer area during the current monitoring period The larger the value, the higher the value. The higher the apparent power fluctuation of a given area during the current monitoring period, the more unstable the apparent power. The higher the probability of a transformer substation generating harmonics during the current monitoring period, the higher the probability characteristic of harmonic generation in that substation, and the two are positively correlated.

[0036] This embodiment calculates the first... Apparent power fluctuation of each transformer area during the current monitoring period With the Rated capacity of transformers in each distribution area The ratio, i.e., the apparent power fluctuation. Compared to the first Rated capacity of transformers in each distribution area The proportion is equivalent to using the first Rated capacity of transformers in each distribution area Apparent power fluctuation After performing dimensionless normalization, the first... The dimensionless result of the apparent power fluctuation of each transformer area during the current monitoring period is compared with the first... The probability characteristics of harmonic generation in each transformer substation during the current monitoring period are positively correlated, which can also be understood as the probability characteristics of harmonic generation in each substation being inversely correlated with the rated capacity of the transformer.

[0037] Based on the above logical analysis, the following is given: A specific formula for calculating the probability characteristics of harmonic generation in a transformer substation during the current monitoring period: ; in, Indicates the first The probability characteristics of harmonic generation in each transformer substation during the current monitoring period.

[0038] It should be understood that if the first [unit] is considered during the calculation... Lower limit of measurement error for smart meters in each distribution area Then calculate the first Apparent power fluctuation of each transformer area during the current monitoring period Lower limit of measurement error of smart meters The sum of these values ​​serves as the total apparent power fluctuation, representing the degree of current load abrupt change. Another specific formula for calculating the probability characteristics of harmonic generation in a transformer substation during the current monitoring period is shown below: .

[0039] This formula utilizes As a safety margin, to prevent small power fluctuations from causing numerical overflow in subsequent calculations, the value of the probability characteristic of harmonic generation in the transformer area is proportional to the degree of current load change and is subject to a strong correlation penalty correction based on the installed capacity of nonlinear equipment.

[0040] Using the above method, the harmonic generation probability characteristics of each transformer substation during the current monitoring time period are obtained. In this embodiment, to facilitate subsequent data processing, after obtaining the harmonic generation probability characteristics of each transformer substation during the current monitoring time period, this embodiment performs a normalization operation on the harmonic generation probability characteristics of each transformer substation during the current monitoring time period. The specific implementation method of the normalization operation is as follows: calculate the sum of the harmonic generation probability characteristics of all transformer substations during the current monitoring time period, and then calculate the ratio of the harmonic generation probability characteristics of each transformer substation during the current monitoring time period to the sum. Using this normalization method, the sum of the harmonic generation probability characteristics of all transformer substations during the current monitoring time period after normalization is 1. It should be understood that if the sum of the harmonic generation probability characteristics of all transformer substations during the current monitoring time period is 0 during normalization, it means that the harmonic generation probability characteristics of all transformer substations during the current monitoring time period are all 0, indicating that no harmonics are generated in any transformer substation during the current monitoring time period. In this case, the subsequent data processing process is terminated, and the harmonic source localization process for the current monitoring time period is no longer executed. The normalization calculation formula is: ; in, Represents the normalized i-th The harmonic generation probability characteristics of each transformer substation during the current monitoring period are as follows: The harmonic generation probability characteristics of the transformer substations mentioned below are all normalized harmonic generation probability characteristics. Indicates the first The probability characteristics of harmonic generation in each transformer substation during the current monitoring period.

[0041] By performing normalization, the output is the first... Harmonic generation probability characteristics of each transformer substation during the current monitoring period , Achieved in The relative proportion within the interval is quantitatively represented, meaning that the closer the value is to 1, the higher the relative probability of a sudden increase / decrease in nonlinear load in the current monitoring period.

[0042] Step S2: Based on the harmonic generation probability characteristics and harmonic impedance attenuation characteristics of each transformer area, divide the total harmonic current increment of the substation to obtain the dynamic responsibility current allocation of each transformer area.

[0043] When high-frequency harmonics from various distribution areas propagate along the distribution network lines to the substation, they undergo natural attenuation due to the impedance characteristics of the line materials. To quantify this spatial impedance penalty in subsequent algorithms, this embodiment determines the harmonic impedance attenuation characteristics based on the physical characteristics of the lines. For the first... The first district, winning the first The actual line length from each transformer substation to the feeder outlet of the substation (Dimension: km). Then obtain the number of... The attenuation constant of the line material between each distribution area and the substation Line material attenuation constant The skin effect coefficient of the conductor material and the conductor cross-sectional area are usually obtained by looking up a table (for example, for a certain standard aluminum stranded wire, the skin effect coefficient can be set). Then, according to the first... The actual line length between each distribution area and the substation , obtained the Harmonic impedance attenuation characteristics of each transformer substation. Among these, the actual line length... The longer the line, the greater the proportion of harmonics consumed by the line impedance during transmission, and the smaller the harmonic impedance attenuation characteristic. The harmonic impedance attenuation characteristic is inversely correlated with the actual line length.

[0044] In an exemplary embodiment, the exponential decay method is used to obtain the first... Harmonic impedance attenuation characteristics of individual transformer areas: ; in, Indicates the first The harmonic impedance attenuation characteristics of each transformer substation, where e represents the natural constant. Therefore, The numerical range is Actual line length The longer the length, the more accurate the calculation. The smaller the value, the greater the proportion of harmonics that are consumed by the line impedance during transmission.

[0045] According to the Harmonic generation probability characteristics of each transformer substation during the current monitoring period Harmonic impedance attenuation characteristics And the division of the total harmonic current increment of the substation , obtained the Dynamic responsibility current allocation for each transformer substation.

[0046] In an exemplary embodiment, firstly according to the first The probability characteristics of harmonic generation and harmonic impedance attenuation of each transformer substation during the current monitoring period are obtained to obtain the first... The harmonic responsibility allocation ratio for each transformer substation during the current monitoring period is as follows. A higher harmonic generation probability characteristic indicates a higher harmonic responsibility allocation ratio, requiring more harmonic current to be allocated; these two are positively correlated. Conversely, a smaller harmonic impedance attenuation characteristic indicates a greater proportion of harmonics being consumed by line impedance during transmission, meaning more severe harmonic attenuation. A lower harmonic responsibility allocation ratio results in less harmonic current to be allocated; these two are also positively correlated. Based on this logical analysis, the following is given... A specific process for obtaining the proportion of harmonic responsibility allocation for each transformer substation during the current monitoring period: First, calculate the... Harmonic generation probability characteristics of each transformer substation during the current monitoring period Harmonic impedance attenuation characteristics The product of: , obtained the The joint allocation weight of each monitoring station area during the current monitoring period. Then, for the first... The joint allocation weight of each district Perform normalization processing and calculate the th... The normalized calculation formula for the harmonic responsibility allocation ratio of each transformer substation during the current monitoring period is as follows: ; in, Indicates the first The proportion of harmonic responsibility allocated to each transformer substation during the current monitoring period. Indicates the first The joint allocation weight of each transformer substation during the current monitoring period. This normalization method ensures that the sum of the harmonic responsibility allocation ratios of all transformer substations during the current monitoring period is 1, thus guaranteeing the total harmonic current increment of the substation. Reasonable allocation.

[0047] It should be understood that if the sum of the joint allocation weights of all transformer substations in the current monitoring time period is 0 during normalization, it means that the joint allocation weights of all transformer substations in the current monitoring time period are all 0. This means that the probability characteristics of harmonic generation of each transformer substation are all 0 in the current monitoring time period, which also indicates that no harmonics are generated in each transformer substation in the current monitoring time period. Therefore, the subsequent data processing process is terminated, and the harmonic source localization process for the current monitoring time period is no longer executed.

[0048] No. Harmonic responsibility allocation ratio for each transformer substation during the current monitoring period Indicates the first The total harmonic current increment of each substation during the current monitoring period. The proportion of harmonic liability borne in the current period, the weight of harmonic liability allocation The larger the value, the more total harmonic current increment of the substation needs to be allocated.

[0049] No. Harmonic responsibility allocation ratio for each transformer substation during the current monitoring period The value is greater than or equal to 0. This calculation method ensures that the final allocation ratio is simultaneously positively stimulated by the degree of load mutation and negatively attenuated by the actual line length. That is, only when a distribution area has both large nonlinear load fluctuations and is sufficiently close to the substation in terms of topological distance can it obtain a larger harmonic responsibility allocation ratio.

[0050] Through the above process, this embodiment completely eliminates the obstacle of solving equations without phase angle data, and successfully obtains the harmonic responsibility allocation ratio corresponding to each transformer area. This data is used to calculate the total harmonic current increment of the substation. It is broken down into the dynamic responsibility current allocation of each transformer substation.

[0051] The harmonic responsibility allocation ratio for each transformer substation during the current monitoring period only reflects the harmonic current increment of each substation during the current monitoring period. However, in actual engineering practice, if a high-pollution transformer substation (such as a steel plant) is in a stable high-harmonic injection state for a long time, its power fluctuation increment during the current monitoring period may be zero, but this does not mean that the substation has stopped outputting harmonics. Therefore, the steady-state heating responsibility of a transformer substation cannot be measured solely by the transient harmonic current increment. To solve the problem of how to quantify the steady-state harmonic current continuously injected by equipment in a transformer substation that has been operating stably for a long time, this embodiment obtains the dynamic responsibility current allocation of each transformer substation based on the sign of the total harmonic current increment of the substation (i.e., whether it is greater than or equal to 0), as follows: Determine the total harmonic current increment of the substation Is it greater than or equal to 0? Increment of total harmonic current in substation When the value is greater than or equal to 0, calculate the harmonic responsibility allocation ratio of each distribution area and the total harmonic current increment of the substation during the current monitoring period. The product of these two values ​​yields the dynamic responsibility current allocation for each transformer substation during the current monitoring period: ; in, Indicates the first The dynamic responsibility current allocation (in A) of each transformer substation during the current monitoring period. Under the positive branch (i.e., the total harmonic current increment of the substation). (Greater than or equal to 0), it is determined that the newly added harmonic heating burden of the entire network should be borne by the transformer area with a sudden increase in load and a relatively short actual line length during the current monitoring period (i.e., Larger districts will share the majority of the additional contribution proportionally.

[0052] Increment of total harmonic current in substation When the value is less than 0 (i.e., overall harmonic improvement across the entire network), obtain the historical harmonic responsibility index inventory for each transformer substation during the previous monitoring period (if in the cold start phase, the initialization results of the historical harmonic responsibility index inventory have been given above), determine the inventory ratio of the historical harmonic responsibility index inventory for each transformer substation during the previous monitoring period, and then calculate the inventory ratio of each transformer substation and the total harmonic current increment of the substation. The product of these factors yields the dynamic responsibility current allocation for each transformer substation: ; in, Indicates the first The historical harmonic responsibility index inventory of each monitoring station area in the previous monitoring period. Indicates the first The historical harmonic responsibility index inventory of each monitoring station area in the previous monitoring period. Indicates the first The percentage of historical harmonic responsibility indicators in each monitoring area during the previous monitoring period.

[0053] It should be understood that, if If the value is 0, it means that the historical harmonic responsibility index inventory of all transformer areas in the previous monitoring period is 0, and the following method can be used for allocation: .

[0054] Increment of total harmonic current in substation When the value is less than 0, it is assumed that when the total harmonic heat generation burden of the entire network is reduced, a proportional reduction should be applied based on the accumulated heat generation responsibility of each transformer substation. This asymmetric incremental calculation logic ensures that the total reduction across the entire network is consistent with the actual total improvement.

[0055] Step S3: Based on the dynamic responsibility current allocation of each transformer area and the historical harmonic responsibility index inventory of the previous adjacent monitoring time period, obtain the latest harmonic responsibility index inventory of each transformer area in the current monitoring time period.

[0056] Step S2 obtains the dynamic responsibility current allocation for each transformer substation during the current monitoring period. To quantify the actual long-term steady-state harmonic output intensity borne by each substation during the current monitoring period, it is necessary to... The dynamic responsibility current allocation of each transformer substation during the current monitoring period is superimposed with the historical harmonic responsibility index inventory from the previous monitoring period to obtain the first... The latest harmonic responsibility index inventory for each transformer area during the current monitoring period: ; in, Indicates the first The latest harmonic responsibility index inventory (dimension A) of each transformer area during the current monitoring period, max represents the maximum value function, realizes the non-negative restriction on the calculation result, and prevents the occurrence of negative heating index that violates the engineering facts under extreme working conditions of continuous large negative deductions, thus ensuring the safe closed loop of the algorithm.

[0057] The temperature rise of transformer windings exhibits thermal inertia; the heat generated by harmonic losses does not disappear instantaneously but dissipates gradually during the heat dissipation process. In mathematical modeling, the aging attenuation coefficient is used to simulate the discretized attenuation of the first-order inertial element, ensuring that the impact of historical harmonic liability on current insulation risks diminishes exponentially over time.

[0058] In another embodiment, the process of obtaining the latest harmonic responsibility index inventory includes: Based on the preset time-decrease coefficient and the historical harmonic responsibility index inventory, the correction amount of the historical harmonic responsibility index inventory is obtained; the latest harmonic responsibility index inventory is obtained by the sum of the correction amount and the dynamic responsibility current allocation amount.

[0059] In the formula, This represents the preset aging attenuation coefficient, with a value ranging from 0.9 to 0.99, and a typical value of 0.95. It is used to characterize the natural dissipation of heat accumulation in the transformer over time, preventing the responsibility index from accumulating indefinitely.

[0060] It should be noted that the core purpose of setting the time-degradation coefficient is to prevent occasional instantaneous harmonic impacts from creating "permanent memory" in the system, and to ensure that when the transformer area manages harmonics or the load decreases, its liability stock can automatically return to the baseline level as the heat dissipation process proceeds.

[0061] The latest harmonic responsibility index inventory for each transformer substation during the current monitoring period integrates the latest dynamic responsibility current allocation and the historical harmonic responsibility index inventory. It should be understood that when the next monitoring period arrives, the latest harmonic responsibility index inventory for each transformer substation during the current monitoring period will automatically be updated to the historical harmonic responsibility index inventory for that current monitoring period.

[0062] Step S4: Integrate the latest harmonic responsibility index inventory and fundamental current RMS value of the target transformer area to obtain the comprehensive electrothermal characteristic load of the target transformer area.

[0063] In order to shield the interference of calculation residuals caused by small fluctuations in the normal safe power load in the distribution network and reduce the workload of ineffective investigation, this embodiment filters all distribution areas based on the latest harmonic responsibility index inventory of each distribution area in the current monitoring time period, thereby selecting distribution areas with higher latest harmonic responsibility index inventory values, and defining the distribution areas with higher latest harmonic responsibility index inventory values ​​as target distribution areas.

[0064] In one exemplary embodiment, a preset inventory threshold is established. This preset threshold can be set according to actual needs. For example, the preset inventory threshold can be set based on the background harmonic limits specified in the national power quality standard GB / T14549. For instance, the permissible harmonic current values ​​for each voltage level of the transformer can be queried, the square root of the sum of the squares of the permissible harmonic current values ​​can be calculated, and 20% to 50% of the result can be used as the preset inventory threshold. For example, for a 10kV distribution transformer, the preset inventory threshold can be set to a fixed value of 5A. This preset inventory threshold is used to filter sampling glitches and normal background harmonic fluctuations, ensuring that subsequent electrothermal assessments only target significant harmonic pollution sources.

[0065] The latest harmonic responsibility index inventory of each transformer substation during the current monitoring period is compared with a preset inventory threshold. Substations with inventory levels exceeding the preset threshold are designated as target substations, which are considered potential sources of harmonic pollution. This process yields the latest harmonic responsibility index inventory for each target substation during the current monitoring period. Other substations not designated as target substations are considered normal, safe nodes that do not generate significant harmonic pollution and are removed from the calculations, terminating subsequent calculations for these non-target substations. It should be understood that if, after the above determination, a target substation cannot be identified, the subsequent data processing process is terminated.

[0066] For any target station area, with the first Taking the target transformer area as an example, determine the first... The effective value of the fundamental current for the target transformer area during the current monitoring period is determined as follows: The process is as follows: Determine the effective value of the fundamental current for the target transformer area during the current monitoring period. The apparent power of each target area during the current monitoring period and obtain the first The rated phase voltage on the secondary side of the transformer in each target distribution area Perform the electrical calculation formula: ; in, Indicates the first The effective value of the fundamental current (in A) of each target transformer area during the current monitoring period.

[0067] Since the actual heat generation of a transformer is determined by both the fundamental load and the harmonic load, and the skin effect and proximity effect generated by mid-to-high frequency harmonics in the transformer windings further amplify eddy current losses, simply superimposing the latest harmonic responsibility index (regardless of frequency) with the effective value of the fundamental current using a simple root-mean-square summation would severely underestimate the heat generation hazard of harmonics. Therefore, this embodiment introduces a preset harmonic heat generation weighting coefficient for equivalent correction. This preset harmonic heat generation weighting coefficient is used to equivalently simulate the additional heat generation penalty of the transformer windings caused by the skin effect of mid-to-high frequency harmonics. Under the same fundamental load, the larger the value of the latest harmonic responsibility index, the larger the calculated comprehensive electrothermal characteristic load, and the heavier the thermal damage burden it bears.

[0068] This embodiment calculates the fundamental current RMS value by integrating it with the latest harmonic responsibility index inventory, as detailed below: To effectively mitigate the heating amplification effect of mid-to-high frequency harmonics, this embodiment weights the latest harmonic responsibility index inventory based on a preset harmonic heating weighting coefficient. This results in a frequency penalty on the latest harmonic responsibility index inventory, yielding a weighted value for the latest harmonic responsibility index inventory. Then, the L2 norm of this weighted value and the effective value of the fundamental current are calculated to obtain the comprehensive electrothermal characteristic load. The calculation formula is as follows: ; in, Indicates the first The comprehensive electrothermal characteristic load (in units of A) of each target transformer area during the current monitoring period. This indicates the preset harmonic heating weighting coefficient. Indicates the first The latest harmonic responsibility index inventory for each target transformer area during the current monitoring period.

[0069] Preset harmonic heating weighting coefficient It can be obtained by setting it based on experience, and the value range is usually between 1.2 and 1.5 (1.3 is taken as an example in this embodiment). Alternatively, it can be an empirical constant determined by the ratio of the equivalent resistance of the transformer winding to the fundamental resistance at the harmonic frequency. The specific value can be determined by the material and structure of the transformer winding, by consulting the stray loss parameters in the transformer's factory test report, or by calculating the ratio of the skin effect loss caused by the harmonic current in the winding to the fundamental loss.

[0070] Using the above process, the comprehensive electrothermal characteristic load of each target area during the current monitoring period is obtained.

[0071] Step S5: Based on the comprehensive electrothermal load characteristics, obtain the transformer insulation degradation risk index for the target distribution area.

[0072] In order to transform the comprehensive electrothermal load into a safety management indicator that can be intuitively judged (i.e., the transformer insulation deterioration risk index), this embodiment introduces a conventional reduced-order temperature rise model and life loss calculation method to perform insulation status assessment and closed-loop dispatch.

[0073] With the first Taking the target transformer area as an example, obtain the first... The rated current (in A) of the transformers in the target distribution area and the first The rated winding hot spot temperature rise constant (in degrees Celsius) of each target transformer area. Among them, the... The rated current of the transformer in the target distribution area is the first The rated current marked on the transformer nameplate of each target distribution area, the first The rated winding hot spot temperature rise constant of the target transformer area represents the first... The rated winding hot spot temperature rise constant of the transformer in each target transformer area under rated full-load conditions, the rated current and the rated winding hot spot temperature rise constant are both inherent known parameters of the transformer. Simultaneously, the [missing information - likely a data point or parameter] is obtained. The ambient temperature (in degrees Celsius) of each target area during the current monitoring period, specifically: in the... Each target monitoring area is equipped with at least one temperature sensor, which obtains multiple ambient temperature values ​​within the current monitoring time period according to a preset temperature sampling cycle. The average value of all ambient temperature values ​​within the current monitoring time period is calculated as the first value. The ambient temperature of each target monitoring area during the current monitoring period. It should be understood that if the temperature sensor is offline or cannot obtain the ambient temperature for other reasons, the preset empirical temperature value corresponding to the season of the current monitoring period will be used as the ambient temperature. For example, 39℃ can be used in summer and 8℃ in winter to avoid data processing interruption.

[0074] The first The rated current of the transformer in each target distribution area, the first The rated winding hot spot temperature rise constant of the target transformer area, the first The ambient temperature of the target area during the current monitoring period and the... The comprehensive electrothermal load characteristic of each target transformer area during the current monitoring period is input into the preset winding temperature rise calculation formula, and the output is the [number]th [unit / area]. The estimated value of the transformer winding hot spot temperature for each target area during the current monitoring period is calculated using the following formula: ; in, Indicates the first Estimated hot spot temperature of transformer windings in each target area during the current monitoring period (in degrees Celsius). Indicates the first The ambient temperature of each target area during the current monitoring period. Indicates the first The rated winding hot spot temperature rise constant of each target transformer area Indicates the first The rated current of the transformers in each target distribution area.

[0075] Then, the first The estimated transformer winding hot spot temperature of each target area during the current monitoring period is input into the transformer insulation aging calculation model based on the Arrhenius rule, and the model outputs the first... The transformer insulation degradation risk index for each target distribution area during the current monitoring period: ; in, Indicates the first The transformer insulation degradation risk index for each target distribution area during the current monitoring period. The formula represents an exponential function with the natural constant as the base. The constant 15000 in the formula represents the activation energy parameter of a specific insulating paper material, with the dimension in degrees Celsius. The constant 110 in the formula represents the reference temperature, with the dimension in degrees Celsius. 273 represents the temperature difference conversion constant between degrees Celsius and Kelvin, with the dimension in degrees Celsius.

[0076] The above calculations show that the... The transformer insulation degradation risk index for each target distribution area falls into three ranges during the current monitoring period: greater than 0 and less than 1, equal to 1, and greater than 1. Overall, the... The higher the transformer insulation degradation risk index value for a target transformer area during the current monitoring period, the faster the lifespan of the transformer insulation material deteriorates during that period. Specifically: when the transformer insulation degradation risk index is greater than 0 and less than 1, it indicates that the transformer is aging at a rate lower than its rated rate. The lower the value, the slower the aging. For example, operating at the current temperature for 1 hour results in an insulation lifespan loss equivalent to operating at 110°C for 0.5 hours (30 minutes), thus extending the transformer's lifespan. This typically corresponds to the transformer operating under light load or low temperature conditions. When the transformer insulation degradation risk index equals 1... When the insulation degradation risk index is greater than 1, it means that the transformer is operating at the current hot spot temperature and its insulation aging rate is exactly the same as when it is operating at the reference temperature (110°C). This means that the transformer is operating at the rated life consumption rate specified by the standard. When the transformer insulation degradation risk index is greater than 1, it means that the transformer is aging at a rate exceeding the rated rate. The larger the value, the faster the aging. For example, if the transformer insulation degradation risk index is equal to 2, it means that operating at the current temperature for 1 hour results in an insulation life loss equivalent to operating at 110°C for 2 hours. This usually corresponds to the transformer being in an overload or cooling system failure state.

[0077] Step S6: Locate the harmonic sources in the distribution network using the transformer insulation degradation risk index.

[0078] Based on the transformer insulation degradation risk index of each target area during the current monitoring period, the source of harmonics in the distribution network is located during the current monitoring period. In an exemplary embodiment, this embodiment presets a risk threshold, which is essentially a safety aging threshold. This preset risk threshold can be obtained through experience. In this embodiment, it can be set to 1.0 or 1.2 according to the requirements of asset life cycle management, indicating that it is not allowed to exceed a specific multiple of the rated life depreciation rate. In order to improve the safety of judgment, this embodiment uses 1.0 as an example.

[0079] Compare the transformer insulation degradation risk index of each target area with the preset risk threshold during the current monitoring period. (Using the first...) Taking the first target area as an example, if the first... If the transformer insulation degradation risk index of a target distribution area is less than or equal to a preset risk threshold during the current monitoring period, then the first target distribution area is determined to be... The operating status of each target transformer area is within the safety margin during the current monitoring period. The target transformer area is not a source of power grid harmonics during the current monitoring period; if the first... If the transformer insulation degradation risk index of a target distribution area is greater than the preset risk threshold during the current monitoring period, then the target distribution area is determined to be... The target transformer area faces a high risk of near-term insulation breakdown during the current monitoring period. The target transformer substation is identified as a harmonic source in the power grid during the current monitoring period. This process identifies the target substations (as harmonic sources) with transformer insulation degradation risk indices exceeding a preset risk threshold. The location of these target substations is determined, for example, by accessing the geographic information system database of the distribution automation master station and extracting the geographic coordinates (latitude, longitude, and line station number) of each target substation with an insulation degradation risk index exceeding the preset risk threshold. After extracting the geographic coordinates, this embodiment combines the geographic coordinates with the transformer insulation degradation risk index to generate a formatted health warning load reduction work order. Finally, this work order is sent via wireless communication to the mobile terminal of the corresponding operation and maintenance team in the relevant area, thereby completing the location of the harmonic source in the distribution network and guiding on-site personnel to perform load reduction or disconnection operations.

[0080] This embodiment also provides an active distribution network harmonic source location system, including: a memory and a processor; the memory is connected to the processor, and the memory is used to store program instructions; the processor is used to implement the steps in the above-described active distribution network harmonic source location method embodiment when the program instructions are executed.

[0081] In one exemplary embodiment, the present invention provides a computer-readable storage medium storing a computer program that, when executed by a processor, implements the steps described in the embodiment of the active distribution network harmonic source localization method.

[0082] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0083] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A method for locating harmonic sources in an active distribution network, characterized in that, include: Determine the probability characteristics of harmonic generation in each transformer area during the current monitoring period; Based on the harmonic generation probability characteristics and harmonic impedance attenuation characteristics of each transformer area, the total harmonic current increment of the substation is divided to obtain the dynamic responsibility current allocation of each transformer area. Based on the dynamic responsibility current allocation of each transformer area and the historical harmonic responsibility index inventory of the previous adjacent monitoring time period, the latest harmonic responsibility index inventory of each transformer area in the current monitoring time period is obtained. The target distribution area is obtained by integrating the latest harmonic responsibility index inventory and the fundamental current RMS value; the target distribution area is selected from the latest harmonic responsibility index inventory. Based on the comprehensive electrothermal load characteristics, the transformer insulation degradation risk index for the target distribution area is obtained; The transformer insulation degradation risk index is used to locate harmonic sources in the distribution network.

2. The method for locating harmonic sources in an active distribution network as described in claim 1, characterized in that, The process of obtaining the probability characteristics of harmonic generation in the transformer area includes: Based on the proportion of nonlinear equipment capacity in the transformer substation during the current monitoring period, the apparent power fluctuation in the transformer substation during the current monitoring period, and the rated capacity of the transformer in the transformer substation, the harmonic generation probability characteristics of the transformer substation during the current monitoring period are obtained. The harmonic generation probability characteristics of the transformer substation are positively correlated with the proportion of nonlinear equipment capacity and the apparent power fluctuation, and negatively correlated with the rated capacity of the transformer.

3. The method for locating harmonic sources in an active distribution network as described in claim 1, characterized in that, The process of obtaining the dynamic responsibility current allocation includes: The harmonic impedance attenuation characteristics of the transformer substation are obtained based on the actual line length between the transformer substation and the substation; the harmonic impedance attenuation characteristics are inversely correlated with the actual line length. Based on the harmonic impedance attenuation characteristics and harmonic generation probability characteristics of the transformer area, the harmonic responsibility allocation ratio of the transformer area is obtained; the harmonic responsibility allocation ratio is positively correlated with both the harmonic impedance attenuation characteristics and the harmonic generation probability characteristics of the transformer area. The dynamic responsibility current allocation of each transformer area is obtained based on the harmonic responsibility allocation ratio of each transformer area and the total harmonic current increment of the substation.

4. The method for locating harmonic sources in an active distribution network as described in claim 3, characterized in that, The dynamic responsibility current allocation for each transformer area is obtained based on the harmonic responsibility allocation ratio of each transformer area and the total harmonic current increment of the substation, including: Determine whether the total harmonic current increment of the substation is greater than or equal to 0; When the total harmonic current increment of the substation is greater than or equal to 0, the product of the harmonic responsibility allocation ratio of each distribution area and the total harmonic current increment of the substation is calculated to obtain the dynamic responsibility current allocation of each distribution area. When the total harmonic current increment of the substation is less than 0, determine the stock ratio of the historical harmonic responsibility index of each distribution area in the previous monitoring period; calculate the product of the stock ratio of each distribution area and the total harmonic current increment of the substation to obtain the dynamic responsibility current allocation of each distribution area.

5. The method for locating harmonic sources in an active distribution network as described in claim 1, characterized in that, The process of obtaining the latest harmonic responsibility index inventory includes: The latest harmonic responsibility index is obtained by summing the historical harmonic responsibility index inventory and the dynamic responsibility current allocation.

6. The method for locating harmonic sources in an active distribution network as described in claim 1, characterized in that, The process of acquiring the target station area includes: Compare the latest harmonic responsibility index inventory of each transformer area with the preset inventory threshold; The transformer area corresponding to the latest harmonic responsibility index inventory that is greater than the preset inventory threshold is determined as the target transformer area.

7. The method for locating harmonic sources in an active distribution network as described in claim 1, characterized in that, The process of obtaining the comprehensive electrothermal characteristic load includes: The weighted value of the latest harmonic responsibility index is obtained by combining the latest harmonic responsibility index inventory of the target transformer area with the preset harmonic heating weighting coefficient. The L2 norm of the weighted value and the effective value of the fundamental current is calculated to obtain the comprehensive electrothermal characteristic load.

8. The method for locating harmonic sources in an active distribution network as described in claim 1, characterized in that, The process of obtaining the transformer insulation degradation risk index includes: Obtain the rated current and rated winding hot spot temperature rise constant of the transformer in the target distribution area; The rated current, rated winding hot spot temperature rise constant, and the electrothermal comprehensive characteristic load are input into the preset winding temperature rise calculation formula, and the estimated value of the transformer winding hot spot temperature of the target area is output. The estimated value of the transformer winding hot spot temperature is input into the transformer insulation aging calculation model based on the Arrhenius rule, and the transformer insulation deterioration risk index is output.

9. The method for locating harmonic sources in an active distribution network as described in claim 1, characterized in that, The method of locating harmonic sources in the distribution network based on the transformer insulation degradation risk index includes: Compare the transformer insulation degradation risk index of each target distribution area with the preset risk threshold. The location of the target transformer area corresponding to the transformer insulation degradation risk index that is greater than the preset risk threshold is determined, thereby realizing the location of the harmonic source in the distribution network.

10. An active distribution network harmonic source location system, characterized in that it comprises: Memory and processor; The memory is connected to the processor; The memory is used to store program instructions; The processor is configured to implement the active distribution network harmonic source localization method according to any one of claims 1-9 when program instructions are executed.

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