Active power distribution network reactive power and voltage collaborative optimization operation method and system

Abstract

The present application relates to the technical field of data acquisition control, in particular to an active power distribution network reactive voltage cooperative optimization operation method and system, comprising the following steps: acquiring feeder node voltage, line reactive power and current direction, identifying pressure drop reversal section, dividing impedance turn-back boundary, locking inverter reactive power propagation section, identifying feeder reactive power flow direction change position, establishing feeder section reactive power propagation sequence, and generating active power distribution network cooperative operation path. In the present application, by identifying feeder pressure drop reversal position, line impedance change boundary and reactive power reverse sending section, the corresponding relationship between feeder level propagation relationship and inverter reactive power propagation range is established, so that the feeder internal pressure drop propagation trend, reactive power flow direction change and inverter output capacity form a cooperative constraint, the risk of reactive power cross-section diffusion, voltage fluctuation expansion and reactive power circulating flow is reduced, and the feeder voltage stability and reactive power regulation accuracy in the high permeability distributed power access scene are improved.

Description

Technical Field

[0001] This invention relates to the field of data acquisition and control technology, and in particular to a method and system for the coordinated optimization of reactive power and voltage operation in active power distribution networks. Background Technology

[0002] The field of data acquisition and control technology involves the continuous acquisition, transmission, processing, and regulation of power distribution network operation status information. This includes voltage data acquisition, current data acquisition, reactive power monitoring, distributed generation operation information acquisition, remote terminal communication, dispatch control, and power distribution automation operation management. It utilizes voltage transformers, current transformers, intelligent measurement and control terminals, remote communication devices, distribution master stations, and field control devices to collect operating parameters in the power distribution system in real time, and performs voltage regulation and reactive power control based on the acquisition results. Among these, the traditional active power distribution network reactive power and voltage coordinated optimization operation method refers to addressing node voltage fluctuations, reactive power flow changes, and line voltage deviations in the power distribution network after the integration of distributed generation. This involves using tap changer regulation, capacitor bank switching, static var compensator regulation, and distributed generation reactive power output regulation to coordinate the control of node voltage and reactive power in the power distribution network. Furthermore, it combines load operation data, network power flow data, and distributed generation operation status data to jointly calculate and regulate the reactive power distribution and voltage operation status in the power distribution network.

[0003] Existing technologies rely on a combination of node voltage results, load operating status, and distributed power source output status for regulation, focusing on overall power flow balance and equipment coordination. However, they lack continuous identification of the direction of voltage drop propagation within feeders, the location of reactive power backflow, and changes in line impedance. This leads to reactive power propagation conflicts between different sections of the line when reverse power flow occurs in the distribution network. For example, in a photovoltaic centralized grid area, reverse reactive power flow may cause a local voltage drop rebound near the busbar. However, the regulation process still performs uniform compensation based on fixed sections, easily resulting in inconsistent reactive power regulation directions between adjacent line sections, further exacerbating the problem at the feeder end. Voltage fluctuations are widening, and the existing regulation process pays less attention to the propagation relationship at the feeder level. The reactive power output range of the inverter is allocated based on the overall capacity, lacking propagation boundary constraints. This leads to reactive power cross-propagation between different feeder sections. When multiple distributed power sources are regulated simultaneously, local reactive power circulation is easily formed, resulting in increased line losses and frequent equipment operation. Furthermore, the existing operation mode lacks continuous analysis of the cumulative voltage drop changes on both sides of the foldback boundary, making it impossible to identify local section voltage deviations in a timely manner. Under long-term operation, this can easily lead to problems such as voltage exceeding limits on the low-voltage side of the distribution transformer, delayed regulation at the feeder end, and repeated switching of reactive power compensation equipment. Summary of the Invention

[0004] To achieve the above objectives, the present invention adopts the following technical solution: a method for coordinated optimization of reactive power and voltage operation in active power distribution networks, comprising the following steps: S1: Obtain feeder node voltage, line reactive power and current direction, calculate the voltage drop change value of adjacent lines, identify the voltage drop reversal location, associate the line reactive power direction, and generate feeder voltage drop reversal distribution section. S2: Based on the feeder voltage drop reversal distribution section, read the reactive power compensation capacitor branch, photovoltaic inverter grid connection line, feeder segment switch section corresponding line reactance, line resistance and reactive current direction, calculate the reactance-resistance ratio and line impedance change rate of each line segment, determine the correspondence between reactive current direction and feeder current direction, record the reactive power feedback corresponding line segment, divide the line segment boundary according to the line impedance change threshold, establish the feeder level sequence number and the section correspondence, and generate the feeder impedance return boundary sequence; S3: Read the inverter reactive power output direction, feeder current propagation direction and inverter reactive power output capacity according to the feeder impedance foldback boundary sequence, identify the inconsistent direction section, lock the propagation section, and generate the inverter reactive power span locking section. S4: Based on the inverter reactive power span locking section, read the node voltage amplitude, line reactive power and line current, calculate the cumulative voltage drop on both sides of the turnaround boundary, identify the location and hierarchical mapping relationship of the section reactive power flow change, and generate the feeder reactive voltage coordinated section. S5: Based on the feeder reactive voltage coordination section, read the inverter node number, reactive output capacity and feeder voltage change direction, match the relationship between the level and the inverter span section, record the node positions of the inverter's allowed reactive power propagation section and prohibited reactive power propagation section, establish the section reactive power propagation sequence, and generate the active distribution network coordinated operation path.

[0005] As a further embodiment of the present invention, the feeder voltage drop reversal distribution section includes a voltage drop reversal node, reactive power correlation direction, and line reversal range; the feeder impedance foldback boundary sequence includes an impedance change boundary, feeder level sequence number, and reactive power feedback section; the inverter reactive power span locking section includes the inverter propagation range, level capacity boundary, and direction conflict section; the feeder reactive power voltage coordination section includes a cumulative voltage drop area, reactive power flow location, and voltage coordination level; the active distribution network coordinated operation path includes reactive power propagation sequence, inverter adjustment node, and feeder coordination path.

[0006] As a further aspect of the present invention, the step of dividing the line segment boundary based on the line impedance change threshold specifically includes: pairing the line reactance and line resistance corresponding to two adjacent lines within the feeder voltage drop reversal distribution segment according to the same line level sequence number to obtain the reactance-resistance ratio and line impedance change rate of each line segment.

[0007] As a further aspect of the present invention, when the line impedance change rate is greater than or equal to the line impedance change threshold, and the reactive current direction is opposite to the feeder current direction, the line segment that meets the conditions is recorded as the reactive power feedback corresponding line segment; the upstream endpoint and downstream endpoint of the reactive power feedback corresponding line segment are respectively used as the line segment boundary, and written into the feeder impedance return boundary sequence according to the feeder level sequence number and the segment correspondence.

[0008] As a further aspect of the present invention, the specific steps of S1 are as follows: S101: Obtain the corresponding node voltage amplitude, line reactive power, and line current direction of the active distribution network feeder bus node, photovoltaic inverter access node, and low-voltage side node of the distribution transformer; call the feeder node voltage amplitude and line current direction to perform node correspondence processing; calculate the voltage drop change value of adjacent line sections according to the feeder topology relationship; establish the line section voltage drop change correspondence relationship; and generate the feeder voltage drop change sequence. S102: Based on the feeder voltage drop change sequence, call the line reactive power direction identifier, determine the order of voltage drop change direction of adjacent line sections, retrieve the line position corresponding to the change direction of voltage drop from load side to bus side, and associate and record the reactive power direction of the corresponding line section to obtain the voltage drop reversal section index set. S103: Based on the voltage drop reversal section index set, call the reactive power direction identifier of the corresponding line section, perform topology connection processing on the reversal line section, perform section merging according to the feeder node connection relationship, and uniformly mark the reactive power direction of each section to generate feeder voltage drop reversal distribution sections.

[0009] As a further aspect of the present invention, the specific steps of S2 are as follows: S201: Based on the feeder voltage drop reversal distribution section, read the reactive power compensation capacitor branch, photovoltaic inverter grid connection line, feeder segment switch section corresponding line reactance, line resistance and reactive current direction, calculate the line reactance resistance ratio and line impedance change rate according to the line segment connection sequence, establish the line segment corresponding parameter mapping relationship, and generate the line impedance change sequence. S202: Based on the line impedance change sequence, call the reactive current direction and the feeder current direction to determine the correspondence between the current directions of the line sections, retrieve the corresponding line sections for reactive power feedback, and perform section boundary division in combination with the line impedance change threshold to obtain the impedance return boundary index set. S203: Based on the impedance return boundary index set, call the feeder level sequence number and line segment connection relationship, perform hierarchical classification processing on the boundary segments, establish the segment correspondence relationship according to the feeder topology order, and serialize and arrange each boundary segment to generate the feeder impedance return boundary sequence.

[0010] As a further aspect of the present invention, the specific steps of S3 are as follows: S301: Based on the feeder impedance foldback boundary sequence, read the reactive power output direction, feeder current propagation direction, and reactive power output capacity of the photovoltaic inverter grid-connected node, feeder tie switch node, and distribution automation terminal node. According to the feeder hierarchy, determine the corresponding reactive power output direction and feeder current propagation direction, establish node direction association, and generate inverter direction association sequence. S302: Based on the inverter direction association sequence, call the inverter reactive power output capacity and feeder node connection relationship, perform span search for line segments with inconsistent directions, and perform segment filtering and determination according to the allowable reactive power capacity corresponding to the feeder level, record the corresponding inverter propagation range, and obtain the inverter propagation segment index set. S303: Based on the inverter propagation segment index set, call the allowable reactive capacity of the feeder level and the connection relationship of the line segment, perform hierarchical classification processing on the inverter propagation segment, perform segment splicing according to the feeder topology order, and mark the propagation segment with continuous sequence to generate the inverter reactive power span locking segment.

[0011] As a further aspect of the present invention, the specific steps of S4 are as follows: S401: Based on the inverter reactive power span locking section, read the voltage amplitude, line reactive power and line current of the corresponding nodes of the feeder segment switch section, distribution transformer low voltage side node, reactive power compensation capacitor branch, and feeder segment voltage drop corresponding relationship, and generate feeder cumulative voltage drop sequence. S402: Based on the cumulative voltage drop sequence of the feeder, call the voltage drop propagation threshold and the reactive power of the line, determine the segment of the correspondence between the cumulative voltage drop value of the feeder and the voltage drop propagation threshold, retrieve the position of reactive power flow change in the feeder segment, record the corresponding feeder level mapping relationship, and obtain the reactive power flow mapping index set; S403: Based on the reactive power flow direction mapping index set, call the feeder hierarchical mapping relationship and line section connection relationship, perform hierarchical classification processing on the reactive power flow direction change section, perform section association according to the feeder topology order, and mark the section with continuous sequence to generate feeder reactive power voltage coordinated section.

[0012] As a further aspect of the present invention, the specific steps of S5 are as follows: S501: Based on the feeder reactive voltage coordination section, read the photovoltaic inverter access node, feeder tie switch section, inverter node number corresponding to the distribution automation master station terminal, reactive output capacity, and feeder voltage change direction, match the feeder level sequence number with the inverter span section according to the feeder level order, establish the inverter section position mapping relationship, and generate the inverter section mapping sequence; S502: Based on the inverter section mapping sequence, call the reactive power output capacity and the direction of feeder voltage change, determine the section of the inverter that is allowed to propagate reactive power and the section that is prohibited from propagating reactive power, and record the corresponding node position and feeder level association relationship to obtain the reactive power propagation node index set. S503: Based on the reactive power propagation node index set, the feeder hierarchical association relationship and line segment connection relationship are called, the reactive power propagation order of the feeder segments is arranged, and the path association processing is performed according to the feeder topology connection order. The propagation segments are marked with continuous paths to generate an active distribution network collaborative operation path.

[0013] An active power distribution network reactive power and voltage coordinated optimization operation system includes: The voltage drop reversal module acquires the corresponding node voltage amplitude, line reactive power, and line current direction of the active distribution network feeder bus nodes, photovoltaic inverter access nodes, and low-voltage side nodes of distribution transformers. It calculates the voltage drop change value of the corresponding line section of adjacent feeder nodes, determines the voltage drop change direction of adjacent line sections, records the line position corresponding to the change direction of voltage drop from decreasing on the load side to decreasing on the bus side, and associates it with the reactive power direction of the corresponding line section to generate the feeder voltage drop reversal distribution section. The impedance boundary module reads the reactive power compensation capacitor branch, photovoltaic inverter grid-connected line, and feeder segment switch section corresponding line reactance, line resistance, and reactive current direction based on the feeder voltage drop reversal distribution section. It calculates the reactance-resistance ratio and line impedance change rate of each line section, determines the correspondence between the reactive current direction and the feeder current direction, records the line section corresponding to reactive power backfeed, divides the line section boundary according to the line impedance change threshold, establishes the correspondence between the feeder level sequence number and the section, and generates the feeder impedance back boundary sequence. The span locking module reads the reactive power output direction, feeder current propagation direction, and inverter reactive power output capacity corresponding to the photovoltaic inverter grid-connected node, feeder tie switch node, and distribution automation terminal node according to the feeder impedance foldback boundary sequence. It determines the correspondence between the inverter reactive power output direction and the feeder current propagation direction, records the inverter span sections corresponding to inconsistent directions, and locks the corresponding inverter propagation sections according to the allowable reactive power capacity at the feeder level, thus generating the inverter reactive power span locking section. The collaborative mapping module reads the voltage amplitude, line reactive power, and line current of the corresponding nodes of the feeder segment switch section, the low-voltage side node of the distribution transformer, and the reactive power compensation capacitor branch based on the inverter reactive power span locking section. It calculates the cumulative voltage drop value of the corresponding feeder on both sides of the turnback boundary, determines the correspondence between the cumulative voltage drop value of the feeder and the voltage drop propagation threshold, records the location of the reactive power flow change of the corresponding feeder section and the feeder level mapping relationship, and generates the feeder reactive power voltage collaborative section. The path generation module reads the photovoltaic inverter access node, feeder tie switch section, corresponding inverter node number of the distribution automation master station terminal, reactive power output capacity, and feeder voltage change direction according to the feeder reactive power voltage coordination section. It matches the correspondence between feeder level sequence number and inverter span section, records the node positions corresponding to the allowed reactive power propagation section and prohibited reactive power propagation section of each inverter, establishes the reactive power propagation sequence of the feeder section, and generates the active distribution network coordinated operation path.

[0014] Compared with the prior art, the advantages and positive effects of the present invention are as follows: In this invention, by identifying the feeder voltage drop reversal location, line impedance change boundary, and reactive power backfeed section, a correspondence between the feeder hierarchical propagation relationship and the inverter reactive power propagation range is established. This enables the feeder internal voltage drop propagation trend, reactive power flow change, and inverter output capacity to form a synergistic constraint, reducing the risk of reactive power cross-section diffusion, voltage fluctuation expansion, and reactive power circulation, and improving feeder voltage stability and reactive power regulation accuracy in high-penetration distributed power access scenarios. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of the steps of the present invention; Figure 2 This is a detailed schematic diagram of S1 of the present invention; Figure 3 This is a detailed schematic diagram of S2 of the present invention; Figure 4 This is a detailed schematic diagram of S3 of the present invention; Figure 5 This is a detailed schematic diagram of S4 of the present invention; Figure 6 This is a detailed schematic diagram of S5 of the present invention; Figure 7 This is a system module diagram of the present invention. Detailed Implementation

[0017] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0018] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0019] Please see Figure 1 This invention provides a method for coordinated optimization of reactive power and voltage operation in active power distribution networks, comprising the following steps: S1: Obtain the voltage amplitude, reactive power, and current direction of the corresponding nodes of the active distribution network feeder bus nodes, photovoltaic inverter access nodes, and low-voltage side nodes of distribution transformers. Calculate the voltage drop change value of the corresponding line section of adjacent feeder nodes, determine the voltage drop change direction of adjacent line sections, record the line position corresponding to the change direction of voltage drop from decreasing on the load side to decreasing on the bus side, and associate it with the reactive power direction of the corresponding line section to generate feeder voltage drop reversal distribution section; S2: Based on the feeder voltage drop reversal distribution section, read the reactive power compensation capacitor branch, photovoltaic inverter grid connection line, feeder segment switch section corresponding line reactance, line resistance and reactive current direction, calculate the reactance-resistance ratio and line impedance change rate of each line section, determine the correspondence between reactive current direction and feeder current direction, record the line section corresponding to reactive power backfeed, divide the line section boundary according to the line impedance change threshold, establish the correspondence between feeder level number and section, and generate feeder impedance return boundary sequence; S3: Based on the feeder impedance foldback boundary sequence, read the reactive power output direction, feeder current propagation direction, and reactive power output capacity of the photovoltaic inverter grid-connected node, feeder tie switch node, and distribution automation terminal node. Determine the correspondence between the reactive power output direction and the feeder current propagation direction. Record the inverter span section corresponding to the inconsistency in direction. Lock the corresponding inverter propagation section according to the allowable reactive power capacity of the feeder level, and generate the inverter reactive power span locking section. S4: Based on the inverter reactive power span locking section, read the voltage amplitude, line reactive power and line current of the corresponding nodes of the feeder segment switch section, distribution transformer low voltage side node, reactive power compensation capacitor branch, calculate the cumulative voltage drop value of the corresponding feeder on both sides of the turnback boundary, determine the correspondence between the cumulative voltage drop value of the feeder and the voltage drop propagation threshold, record the location of the reactive power flow change of the corresponding feeder section and the feeder level mapping relationship, and generate the feeder reactive power voltage coordination section; S5: Based on the feeder reactive voltage coordination section, read the photovoltaic inverter access node, feeder tie switch section, corresponding inverter node number of the distribution automation master station terminal, reactive output capacity, and feeder voltage change direction, match the feeder level sequence number with the inverter span section correspondence, record the node positions of each inverter's allowed reactive power propagation section and prohibited reactive power propagation section, establish the feeder section reactive power propagation sequence, and generate the active distribution network coordinated operation path.

[0020] The feeder voltage drop reversal distribution section includes the voltage drop reversal node, reactive power correlation direction, and line reversal range; the feeder impedance foldback boundary sequence includes the impedance change boundary, feeder level sequence, and reactive power backfeed section; the inverter reactive power span locking section includes the inverter propagation range, level capacity boundary, and direction conflict section; the feeder reactive power voltage coordination section includes the cumulative voltage drop area, reactive power flow location, and voltage coordination level; the active distribution network coordinated operation path includes the reactive power propagation sequence, inverter adjustment node, and feeder coordination path.

[0021] Please see Figure 2 The specific steps of S1 are as follows: S101: Obtain the corresponding node voltage amplitude, line reactive power, and line current direction of the active distribution network feeder bus node, photovoltaic inverter access node, and low-voltage side node of the distribution transformer; call the feeder node voltage amplitude and line current direction to perform node correspondence processing; calculate the voltage drop change value of adjacent line sections according to the feeder topology relationship; establish the line section voltage drop change correspondence relationship; and generate the feeder voltage drop change sequence. The real-time voltage amplitude of the 10 kV feeder bus node is read through the feeder bus node voltage acquisition terminal, the voltage amplitude of the inverter grid connection point is read through the photovoltaic inverter access node acquisition terminal, and the voltage amplitude of the 0.4 kV side node is read through the low-voltage side measurement port of the distribution transformer. Simultaneously, reactive power flow data for each line section is obtained from the line reactive power detection circuit, and line current direction data is obtained from the line current transformer. Five sets of data are continuously acquired for the feeder node voltage amplitude using a sampling method of once every 200 milliseconds. After removing instantaneous outliers, the median value is retained as the current node voltage amplitude. Taking a certain 10 kV feeder as an example, the feeder bus node voltage amplitude is 10.42 kV, the voltage amplitude of the first photovoltaic inverter access node is 10.37 kV, the voltage amplitude of the second branch node is 10.21 kV, and the converted voltage amplitude of the low-voltage side of the distribution transformer is 10.08 kV. Subsequently, node correspondence processing is performed according to the feeder topology connection sequence, sequentially associating the feeder bus node number, line start node number, and line end node number to form a line segment connection chain. During the calculation of line segment voltage drop changes, the voltage amplitude of adjacent nodes is used to perform difference calculations. The voltage drop value for the first line segment is 0.05 kV, the voltage drop value for the second line segment is 0.16 kV, and the voltage drop value for the third line segment is 0.13 kV. Then, the voltage drop values ​​of each line segment are sequentially arranged to generate a feeder voltage drop change sequence. Line current direction is identified using two types of indicators: forward flow and reverse flow. Current direction consistent with the feeder topology direction is recorded as forward propagation, and inconsistent as reverse propagation. Reactive power direction is recorded using a propagation method from the line start point to the line end point. When the reactive power detection value exceeds 0.12 Mvar three consecutive times, it is marked as a stable output segment. During the establishment of the voltage drop change correspondence, the line number, voltage drop value, current direction, and node level number are simultaneously written into the feeder voltage drop data table. Table 1 lists the feeder voltage drop acquisition data.

[0022] Table 1. Feeder Voltage Drop Data Collection Table

[0023] As shown in Table 1, the voltage drop change value of the second line section reached 0.16 kV, which is higher than the preset voltage drop fluctuation threshold of 0.12 kV. Therefore, the voltage drop reversal retrieval operation was triggered in the subsequent processing.

[0024] S102: Based on the feeder voltage drop change sequence, call the reactive power direction identifier of the line, determine the order of voltage drop change direction of adjacent line sections, retrieve the line position corresponding to the change direction of voltage drop from load side to bus side, and record the reactive power direction of the corresponding line section to obtain the voltage drop reversal section index set. The voltage drop change direction of each line section is read sequentially according to the feeder voltage drop change sequence, and the reactive power direction identifier of the line is called simultaneously to perform directional correlation processing. The voltage drop change direction is identified by the decreasing node voltage direction. When the voltage of the end node of the line is lower than the voltage of the beginning node of the line, it is recorded as a load-side decrease; when the voltage of the end node of the line is higher than the voltage of the beginning node of the line, it is recorded as a bus-side decrease. Taking feeder sections 2 and 3 as examples, the voltage drop value of section 2 decreases from 10.37 kV to 10.21 kV, which is recorded as a load-side decrease. In section 3, due to the reactive power backfeed effect of the inverter, the voltage drop trend of the line terminal slows down, and the voltage drop change amplitude is smaller than that of the previous line section. Therefore, it is recorded as a section with a slowing voltage drop, and the reverse propagation judgment is further performed in combination with the reactive power direction. Subsequently, the direction comparison is performed according to the line topology order. When the direction identifier of consecutive adjacent sections changes, the position of the corresponding line section is immediately recorded. Reactive power direction identification is synchronously recorded. If the reactive power direction of the line is opposite to the normal power flow direction of the feeder, it is marked as a reactive power reverse transmission section. During the reactive power direction determination process, the reactive power sampling value of the line is called to perform 5 average calculations. If the average value is greater than 0.15 Mvar, it is recorded as positive reactive power output; if the average value is less than -0.15 Mvar, it is recorded as reverse reactive power output. Taking the 3rd line section as an example, the 5 consecutive reactive power measurements are -0.18 Mvar, -0.17 Mvar, -0.19 Mvar, -0.16 Mvar, and -0.18 Mvar, respectively. The calculated average value is -0.176 Mvar, so it is recorded as a reverse reactive power output section. During the voltage drop reversal section indexing and recording process, the line section number, voltage drop change direction, reactive power direction, and node level number are written into the reversal index table. When the voltage drop direction change number of adjacent line sections reaches more than 2 times, the duplicate reversal is eliminated, and only stable reversal sections with a duration of more than 3 seconds are retained. The operation node is responsible for calculating the direction reversal result based on the voltage drop change value and the reactive power direction, thereby triggering the reversal line segment merging operation.

[0025] S103: Based on the voltage drop reversal section index set, call the reactive power direction identifier of the corresponding line section, perform topology connection processing on the reversal line section, perform section merging according to the feeder node connection relationship, and uniformly mark the reactive power direction of each section to generate feeder voltage drop reversal distribution sections. The line topology connection sequence is arranged according to the feeder level number, with the main feeder level number being 1, and the branch feeder level numbers increasing sequentially. For line sections with continuous levels and consistent reactive power direction, section merging is performed. Taking feeder sections 3 and 4 as examples, section 3 has a level number of 2, and section 4 has a level number of 3. Both sections have reverse reactive power output, so section splicing is performed to generate a new feeder voltage drop reverse distribution section. During the section merging process, the line connection relationship table is first called to check whether the endpoint node numbers of the two sections are consistent. If the node interval is no more than 1 level, a continuous connection relationship is established. Subsequently, the reactive power direction of each section is uniformly marked. When the proportion of reverse reactive power output in a section exceeds 70%, the entire section is marked as a reverse propagation section. Taking a certain power distribution line as an example, the reverse reactive power output duration of section 3 is 4.8 seconds, and the reverse reactive power output duration of section 4 is 5.1 seconds. The total duration of the two sections reaches 9.9 seconds, exceeding the preset stable section duration threshold of 6 seconds. Therefore, a stable voltage drop reversal section is generated. After the section splicing is completed, the section start node number, end node number, duration, and average voltage drop value are synchronously written into the feeder voltage drop reversal data table. The average voltage drop value is obtained by summing all voltage drop changes within the section and dividing by the number of lines. For example, the voltage drop value of section 3 is -0.08 kV, and the voltage drop value of section 4 is -0.11 kV. The calculated average voltage drop value is -0.095 kV. This result is then compared with the preset reversal voltage drop benchmark value of -0.06 kV. Since -0.095 kV exceeds the benchmark range, it is retained as an effective feeder voltage drop reversal distribution section and enters the subsequent line impedance change processing stage.

[0026] Please see Figure 3 The specific steps of S2 are as follows: S201: Based on the feeder voltage drop reversal distribution section, read the reactive power compensation capacitor branch, photovoltaic inverter grid connection line, feeder segment switch section corresponding line reactance, line resistance and reactive current direction, calculate the line reactance resistance ratio and line impedance change rate according to the line segment connection sequence, establish the corresponding parameter mapping relationship of the line segment, and generate the line impedance change sequence. Line reactance and resistance values ​​are obtained through an online monitoring terminal, which updates impedance parameters every second. Taking a 10kV feeder as an example, the reactance of section 3 is 0.41 ohms and the resistance is 0.16 ohms, while the reactance of section 4 is 0.47 ohms and the resistance is 0.18 ohms. Subsequently, the reactance-resistance ratio is calculated according to the connection order of the line sections, dividing the reactance by the resistance. For section 3, the ratio is 2.56, and for section 4, it is 2.61. The impedance change rate is obtained by comparing the impedance difference between adjacent sections with the impedance value of the preceding section; the impedance change rate for section 4 reaches 1.95%. A parameter mapping relationship for the line sections is then established, synchronously writing the section number, reactance-resistance ratio, impedance change rate, and reactive current direction into the parameter mapping table. The direction of reactive current is identified based on the data collected by the current transformer. When the direction of reactive current is consistent with the normal power supply direction of the feeder, it is recorded as forward propagation; when it is reversed, it is recorded as back propagation. Taking section 4 as an example, the direction of reactive current showed reverse propagation in four consecutive samples, therefore it is recorded as a stable back propagation section. During the generation of the line impedance change sequence, the impedance change rate of all line sections is sorted in ascending order, and the node level number is marked simultaneously. If the impedance change rate of a certain line section exceeds 1.5%, the subsequent impedance back boundary retrieval operation is triggered. The key to this step is to calculate the line impedance change rate by jointly calculating the line reactance value, the line resistance value, and the direction of reactive current, thereby triggering the boundary section determination process.

[0027] S202: Based on the line impedance change sequence, call the reactive current direction and feeder current direction to determine the correspondence of the current direction in the line section, retrieve the corresponding line section for reactive power feedback, and perform section boundary division in combination with the line impedance change threshold to obtain the impedance return boundary index set. When the feeder current propagates from the bus node to the load node, it is recorded as forward propagation; when it propagates from the terminal node to the bus node, it is recorded as reverse propagation. When the reactive current direction is opposite to the feeder current direction, it is immediately recorded as a reactive power backfeeding section. Taking the 4th line section as an example, the feeder current direction is from the bus to the load, while the reactive current direction is from the load to the bus, therefore it is determined to be a reactive power backfeeding section. Subsequently, the section boundary is divided based on the line impedance change threshold, which is obtained from historical operating data. The 30-day continuous operating record shows that the impedance change rate of normal sections is concentrated between 0.3% and 1.2%, so 1.5% is set as the impedance backfeeding boundary threshold. The impedance change rate of the 4th section reaches 1.95%, exceeding the boundary threshold, and is therefore recorded as an impedance backfeeding boundary section. During the boundary division process, the start and end node numbers of the line section are called for continuity verification. If the impedance change rates of adjacent sections simultaneously exceed the threshold and the hierarchical interval does not exceed 1 level, then boundary expansion processing is performed. Taking segments 4 and 5 as examples, the impedance change rate of segment 5 is 1.71%. Since the node levels of the two segments are continuous, a joint boundary segment is generated. Subsequently, the joint boundary segment number, average impedance change rate, and reverse reactive power duration are written into the impedance return boundary index table. The average impedance change rate is obtained by averaging the change rates of segments 4 and 5, resulting in 1.83%. This result is higher than the preset stability boundary value of 1.6%, therefore it is retained in the impedance return boundary index set.

[0028] S203: Based on the impedance return boundary index set, call the feeder level sequence number and line segment connection relationship, perform hierarchical classification processing on the boundary segments, establish the segment correspondence relationship according to the feeder topology order, and serialize and arrange each boundary segment to generate the feeder impedance return boundary sequence. The feeder level sequence is generated through a feeder topology scan process, with the bus node level starting at 1 and increasing by one level for each branch node. For example, the fourth line segment has a level number of 3, and the fifth line segment has a level number of 4. Subsequently, the segment correspondence is established according to the feeder topology order, and segments with continuous levels and consistent boundary attributes are sequentially arranged. During the sequential arrangement, the segment with the longest reverse reactive power propagation time is recorded first, and then arranged in descending order of propagation time. The reverse propagation duration for the fourth segment is 5.6 seconds, and for the fifth segment it is 4.9 seconds, therefore the fourth segment is listed first. Then, continuous numbering is performed on the boundary segments to generate a feeder impedance feedback boundary sequence. The boundary sequence synchronously records the segment start and end nodes, impedance change rate, reactive power feedback duration, and corresponding feeder level number. For example, the fourth segment has an impedance change rate of 1.95%, a reactive power feedback duration of 5.6 seconds, and a node span of level 2. Subsequently, a validity check is performed by applying the boundary stability threshold. A boundary segment is recorded as stable when its duration exceeds 4 seconds and its impedance change rate exceeds 1.5%. Experimental data shows that in the same feeder, when the impedance change rate is below 1.2%, the boundary identification error reaches 18%, while using a 1.5% boundary threshold reduces the error to 6%. This experimental result indicates that the accuracy of impedance foldback boundary identification is improved by 12% after adopting a hierarchical continuous classification method. The key to this step is to obtain the boundary sequence result based on the hierarchical sequence number and the segment impedance change rate, thereby triggering the inverter direction association processing.

[0029] Please see Figure 4 The specific steps of S3 are as follows: S301: Based on the feeder impedance foldback boundary sequence, read the reactive power output direction, feeder current propagation direction, and reactive power output capacity of the photovoltaic inverter grid-connected node, feeder tie switch node, and distribution automation terminal node. According to the feeder hierarchy, determine the corresponding reactive power output direction and feeder current propagation direction, establish the node direction association relationship, and generate the inverter direction association sequence. The inverter's reactive power output direction is read in real time through the inverter's sampling port, while the feeder current propagation direction is obtained through the feeder current transformer. Taking the third inverter node of a certain feeder as an example, the inverter's reactive power output direction propagates from the load side to the bus side, while the feeder current propagation direction propagates from the bus side to the load side; the two directions are inconsistent. Subsequently, direction correspondence determination is performed according to the feeder hierarchy, establishing a direction association relationship for each inverter node. The inverter's reactive power output capacity is read through the inverter control terminal, with a reading period of 500 milliseconds. The reactive power output capacity of the third inverter node is 0.42 Mvar, and the reactive power output capacity of the fourth inverter node is 0.38 Mvar. Then, a node direction association table is established, synchronously recording the inverter node number, feeder hierarchy number, reactive power output direction, and feeder current direction. During the direction correspondence determination process, if the inverter's reactive power output direction and the feeder current propagation direction are inconsistent for more than 3 seconds, it is immediately recorded as a direction abnormal node. Taking the third inverter node as an example, inconsistent directions were observed in seven consecutive samples, thus generating a direction anomaly marker. After the inverter direction association sequence was generated, the node information was arranged sequentially according to the feeder hierarchy, and reactive power capacity was aggregated for nodes at the same level. The third level has two inverter nodes, with a total reactive power output capacity of 0.8 Mvar. This result was then compared with the level's allowable capacity threshold of 0.65 Mvar. Since 0.8 Mvar exceeded the allowable capacity, an inverter propagation range retrieval operation was triggered.

[0030] S302: Based on the inverter direction association sequence, call the inverter reactive output capacity and feeder node connection relationship, perform span search for line sections with inconsistent directions, and perform section filtering and determination according to the allowable reactive capacity corresponding to the feeder level, record the corresponding inverter propagation range, and obtain the inverter propagation section index set. The node connections are scanned sequentially according to the feeder hierarchy. When the reactive power output direction between adjacent nodes is consistently inconsistent, the corresponding line segment is recorded as a propagation segment. Taking the 3rd inverter node as an example, its corresponding 4th and 5th segments both have inconsistent directions, thus the propagation span reaches two line segments. Subsequently, segment screening and determination are performed based on the allowable reactive power capacity at the feeder hierarchy. The allowable reactive power capacity at the feeder hierarchy is determined based on historical operating data. The allowable capacity range for the 3rd level is 0.3 Mvar to 0.65 Mvar, and the allowable capacity range for the 4th level is 0.2 Mvar to 0.5 Mvar. The reactive power output capacity of the 3rd inverter node reaches 0.42 Mvar, which is within the allowable range, and the capacity of the 4th inverter node reaches 0.38 Mvar, which also meets the capacity condition. Therefore, the propagation segments corresponding to both nodes are retained. Then, the inverter propagation range is recorded, and the starting node, ending node, and propagation duration are simultaneously written into the propagation segment index table. The propagation duration was obtained using a continuous directional abnormal duration statistical method. The propagation duration at the third inverter node reached 6.2 seconds. This result exceeded the preset effective propagation threshold of 5 seconds and was therefore recorded as a valid propagation segment. Experimental data showed that when the propagation duration was less than 3 seconds, the line misclassification rate reached 21%. After adopting the 5-second threshold, the misclassification rate decreased to 7%. These experimental results demonstrate that the duration screening and determination method can stabilize the propagation segment identification results.

[0031] S303: Based on the inverter propagation section index set, call the allowable reactive capacity of the feeder level and the connection relationship of the line section, perform hierarchical classification processing of the inverter propagation section, perform section splicing according to the feeder topology order, and mark the propagation section with continuous sequence to generate the inverter reactive power span locking section. Continuous propagation segments within the same feeder level are merged and spliced ​​according to the feeder topology. Taking segments 4 and 5 as examples, the two segments are hierarchically continuous and propagate in the same direction, thus generating a unified propagation segment. Subsequently, a continuous sequence label is applied to the propagation segment, including the segment number, level span, total reactive power output capacity, and duration. The total reactive power output capacity is obtained by summing the reactive power output capacities of all inverter nodes within the propagation segment. The capacity of the 3rd inverter node is 0.42 Mvar, and the capacity of the 4th inverter node is 0.38 Mvar, totaling 0.8 Mvar. This 0.8 Mvar is then compared to the feeder's allowed propagation capacity limit of 0.75 Mvar. Since it exceeds the limit, a high propagation level label is added to the propagation segment. During segment splicing, the line segment connection relationship table is called to verify node continuity; splicing terminates when the node interval exceeds one level. Inverter reactive power span locked segments are generated, and the average propagation distance of the segments is recorded simultaneously. The propagation distance is obtained by dividing the total length of the segments by the number of segments. For example, the length of segment 4 is 0.8 kilometers, the length of segment 5 is 1.1 kilometers, and the total propagation distance reaches 1.9 kilometers. This result exceeds the benchmark value of 1.5 kilometers for propagation distance, so it is identified as a key propagation segment and enters the cumulative pressure drop analysis stage.

[0032] Please see Figure 5 The specific steps of S4 are as follows: S401: Based on the inverter reactive power span locking section, read the voltage amplitude, line reactive power and line current of the corresponding nodes of the feeder segment switch section, distribution transformer low voltage side node, reactive power compensation capacitor branch, and feeder segment voltage drop value on both sides of the feeder topology connection order, and establish the feeder segment voltage drop correspondence relationship to generate the feeder cumulative voltage drop sequence. Node voltage amplitude is obtained through the distribution automation terminal, line reactive power is obtained through the reactive power sampling circuit, and line current is obtained through the current transformer. Then, the cumulative voltage drop on both sides of the turnback boundary is calculated according to the feeder topology connection sequence. The cumulative voltage drop is obtained by continuously accumulating the voltage drop values ​​of each line segment. Taking segments 4 and 5 as examples, the voltage drop value of segment 4 is 0.14 kV, and the voltage drop value of segment 5 is 0.11 kV, resulting in a cumulative voltage drop value of 0.25 kV. Subsequently, the voltage drop correspondence between feeder segments is established, and the line segment number, cumulative voltage drop value, and reactive power direction are recorded synchronously. The reactive power direction is determined by averaging three consecutive samples. The average reactive power value of segment 4 is -0.21 Mvar, and the average reactive power value of segment 5 is -0.18 Mvar; therefore, both are recorded as reverse propagation segments. After the feeder cumulative voltage drop sequence is generated, it is arranged in descending order of cumulative voltage drop value. If the cumulative voltage drop exceeds 0.22 kV, a subsequent reactive power flow change retrieval is triggered. The cumulative voltage drop in sections 4 and 5 reaches 0.25 kV, exceeding the threshold, thus entering the reactive power flow mapping stage. Experimental data shows that when the cumulative voltage drop is below 0.18 kV, the line voltage drop volatility reaches 14%. After adopting a 0.22 kV threshold, the voltage drop volatility decreases to 5%.

[0033] S402: Based on the cumulative voltage drop sequence of the feeder, call the voltage drop propagation threshold and the reactive power of the line, determine the section of the correspondence between the cumulative voltage drop value of the feeder and the voltage drop propagation threshold, retrieve the location of the reactive power flow change in the feeder section, record the corresponding feeder level mapping relationship, and obtain the reactive power flow mapping index set; The voltage drop propagation threshold is determined based on historical voltage drop statistics. The normal feeder voltage drop propagation range is concentrated between 0.08 kV and 0.2 kV; therefore, 0.22 kV is set as the propagation judgment threshold. Subsequently, the location of reactive power flow change in the feeder section is retrieved. When the cumulative voltage drop exceeds 0.22 kV and reactive power propagates in the reverse direction, the corresponding line section is immediately recorded. Taking section 4 as an example, the cumulative voltage drop reaches 0.25 kV, and the average reactive power is -0.21 Mvar; therefore, it is recorded as a reactive power flow change section. The corresponding feeder level mapping relationship is then recorded, and the line section number, level number, voltage drop value, and reactive power value are written into the mapping index table. During the level mapping process, consecutive reverse propagation sections are merged. Both sections 4 and 5 exhibit reverse propagation, thus generating a joint reactive power flow change section. The average voltage drop value of the joint section is then calculated, reaching 0.24 kV. The result is 0.2 kV higher than the stable propagation reference value, and therefore is retained in the reactive power flow direction mapping index set. The key to this step is to obtain the flow direction change result by jointly calculating the cumulative voltage drop value and the reactive power direction, thereby triggering the segment correlation processing.

[0034] S403: Based on the reactive power flow direction mapping index set, call the feeder hierarchical mapping relationship and line section connection relationship, perform hierarchical classification processing on reactive power flow direction change sections, perform section association according to feeder topology order, and mark the sections as a continuous sequence to generate feeder reactive power voltage coordination sections. Continuous reactive power back propagation sections within the same level are uniformly associated. Taking sections 4 and 5 as examples, both sections are hierarchically continuous and exhibit reverse reactive power propagation, thus section association is performed. Subsequently, the associated sections are continuously sequenced according to the feeder topology, generating feeder reactive voltage coordinated sections. The cumulative voltage drop, average reactive power, and section length are recorded synchronously within each coordinated section. Section 4 has a length of 0.8 km, and section 5 has a length of 1.1 km, with a cumulative length of 1.9 km. The average reactive power value of the coordinated sections is then calculated. The average reactive power of section 4 is -0.21 Mvar, and the average reactive power of section 5 is -0.18 Mvar, resulting in a calculated average of -0.195 Mvar. This result is compared to the coordinated operation benchmark value of -0.15 Mvar. Since it exceeds the benchmark range, it is recorded as a key coordinated section. Table 2 lists the coordinated section operation data.

[0035] Table 2. Collaborative Section Operation Data Table

[0036] As shown in Table 2, the cumulative voltage drop in the first collaborative section reached 0.24 kV, thus triggering the inverter section mapping operation in subsequent processing.

[0037] Please see Figure 6 The specific steps of S5 are as follows: S501: Based on the feeder reactive voltage coordination section, read the photovoltaic inverter access node, feeder tie switch section, corresponding inverter node number of the distribution automation master station terminal, reactive output capacity, and feeder voltage change direction, match the feeder level sequence number with the inverter span section according to the feeder level order, establish the inverter section position mapping relationship, and generate the inverter section mapping sequence; Inverter node numbers are obtained from the grid connection registration table, reactive power output capacity is collected in real time by the inverter control terminal, and the direction of feeder voltage change is obtained through the voltage difference between feeder nodes. Then, the correspondence between feeder level numbers and inverter span sections is matched according to the feeder level sequence. Taking level 3 as an example, the inverter node number is 103, and the span section covers sections 4 and 5. The reactive power output capacity of inverter node 103 is 0.42 Mvar, and the feeder voltage change direction shows a rise in bus-side voltage. Subsequently, an inverter section location mapping relationship is established, and the node number, section number, level number, and reactive power output capacity are synchronously written into the section mapping table. During the section location mapping process, capacity aggregation is performed on multiple inverter nodes within the same section. Section 4 has 2 inverter nodes, with a total reactive power output capacity of 0.8 Mvar. This 0.8 Mvar is then compared with the section capacity limit of 0.75 Mvar. Since it exceeds the limit, a high-capacity propagation marker is added to this section. After the inverter section mapping sequence is generated, it is arranged sequentially according to the feeder topology, and the voltage change direction is recorded synchronously. If the voltage change direction shows a bus-side rise for three consecutive times, the reactive power propagation section determination operation is triggered.

[0038] S502: Based on the inverter section mapping sequence, call the reactive power output capacity and feeder voltage change direction to determine the section of the inverter that is allowed to propagate reactive power and the section that is prohibited from propagating reactive power. Record the corresponding node position and feeder level association relationship to obtain the reactive power propagation node index set. The permissible reactive power propagation section is determined using a combined method of capacity range and voltage change direction. When the inverter's reactive power output capacity is lower than the upper limit of the level's permissible capacity and the feeder voltage change direction is stable, it is recorded as a permissible propagation section. Taking section 5 as an example, the reactive power output capacity is 0.38 Mvar, and the upper limit of the level's permissible capacity is 0.5 Mvar, therefore it is recorded as a permissible propagation section. Section 4's reactive power output capacity reaches 0.8 Mvar, exceeding the section capacity limit of 0.75 Mvar, therefore it is recorded as a prohibited propagation section. Subsequently, the relationship between node location and feeder level is recorded, and the node number, level number, section type, and duration are synchronously written into the reactive power propagation node index table. The duration is obtained through statistical analysis of continuous directional stability sampling results. The directional stability duration of section 5 reaches 6.5 seconds, therefore it is retained as a valid propagation section. Experimental data shows that when the reactive power output capacity exceeds the level's permissible capacity by more than 10%, the voltage fluctuation rate at the feeder end reaches 17%. After using the prohibited propagation section restriction, the voltage fluctuation rate at the end decreases to 6%. The experimental results show that the capacity range determination method can stabilize the range of feeder voltage variation.

[0039] S503: Based on the reactive power propagation node index set, call the feeder hierarchical association relationship and line section connection relationship, perform reactive power propagation order arrangement on the feeder sections, perform path association processing according to the feeder topology connection order, mark the propagation sections as continuous paths, and generate active distribution network collaborative operation path; The allowed propagation sections are recorded first, and path association processing is performed according to the feeder topology connection order. Taking section 5 as an example, section 5 is an allowed propagation section, so it is placed at the beginning of the propagation path. Then, continuous path marking is performed on the propagation sections. The path marking content includes the path number, starting node, ending node, propagation capacity, and propagation distance. The propagation capacity is obtained by summing the reactive power output capacity of all inverter nodes within the path. The propagation capacity of section 5 is 0.38 Mvar, and the propagation capacity of section 6 is 0.27 Mvar, totaling 0.65 Mvar. The total propagation path length is then calculated. The length of section 5 is 1.1 km, and the length of section 6 is 0.7 km, totaling 1.8 km. Comparing 0.65 Mvar with the upper limit of the allowed propagation capacity of 0.7 Mvar, since it is within the allowed range, it is retained as a valid cooperative operation path. The propagation path number, capacity value, path length, and node level number are then synchronously written into the active distribution network cooperative operation path table. Table 3 lists the cooperative operation path data.

[0040] Table 3 Collaborative Operation Path Data Table

[0041] Referring to Table 3, the propagation capacity of the first propagation path reaches 0.65 Mvar, which is within the allowable propagation capacity range of 0.3 Mvar to 0.7 Mvar. Therefore, an effective active distribution network cooperative operation path is generated, and continuous path marking processing is completed.

[0042] Please see Figure 7 An active power distribution network reactive power and voltage coordinated optimization operation system includes: The voltage drop reversal module acquires the corresponding node voltage amplitude, line reactive power, and line current direction of the active distribution network feeder bus nodes, photovoltaic inverter access nodes, and low-voltage side nodes of distribution transformers. It calculates the voltage drop change value of the corresponding line section of adjacent feeder nodes, determines the voltage drop change direction of adjacent line sections, records the line position corresponding to the change direction of voltage drop from decreasing on the load side to decreasing on the bus side, and associates it with the reactive power direction of the corresponding line section to generate the feeder voltage drop reversal distribution section. The impedance boundary module reads the reactive power compensation capacitor branch, photovoltaic inverter grid-connected line, and feeder segment switch section corresponding line reactance, line resistance, and reactive current direction based on the feeder voltage drop reversal distribution section. It calculates the reactance-resistance ratio and line impedance change rate of each line section, determines the correspondence between the reactive current direction and the feeder current direction, records the line section corresponding to reactive power backfeed, divides the line section boundary according to the line impedance change threshold, establishes the correspondence between feeder level number and section, and generates the feeder impedance back boundary sequence. The span locking module reads the reactive power output direction, feeder current propagation direction, and inverter reactive power output capacity corresponding to the photovoltaic inverter grid-connected node, feeder tie switch node, and distribution automation terminal node based on the feeder impedance foldback boundary sequence. It determines the correspondence between the inverter reactive power output direction and the feeder current propagation direction, records the inverter span sections corresponding to inconsistent directions, and locks the corresponding inverter propagation sections based on the allowable reactive power capacity at the feeder level, thus generating the inverter reactive power span locking section. The collaborative mapping module reads the voltage amplitude, line reactive power, and line current of the corresponding nodes of the feeder segment switch section, distribution transformer low-voltage side node, and reactive power compensation capacitor branch based on the inverter reactive power span locking section. It calculates the cumulative voltage drop value of the corresponding feeder on both sides of the turnback boundary, determines the correspondence between the cumulative voltage drop value of the feeder and the voltage drop propagation threshold, records the location of the reactive power flow change in the corresponding feeder section and the feeder level mapping relationship, and generates the feeder reactive power voltage collaborative section. The path generation module reads the photovoltaic inverter access node, feeder tie switch section, corresponding inverter node number of the distribution automation master station terminal, reactive power output capacity, and feeder voltage change direction based on the feeder reactive power voltage coordination section. It matches the correspondence between the feeder level sequence number and the inverter span section, records the node positions corresponding to the allowed reactive power propagation section and the prohibited reactive power propagation section of each inverter, establishes the reactive power propagation sequence of the feeder section, and generates the active distribution network coordinated operation path.

[0043] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for coordinated optimization of reactive power and voltage operation in active power distribution networks, characterized in that, Includes the following steps: S1: Obtain feeder node voltage, line reactive power and current direction, calculate the voltage drop change value of adjacent lines, identify the voltage drop reversal location, associate the line reactive power direction, and generate feeder voltage drop reversal distribution section. S2: Based on the feeder voltage drop reversal distribution section, read the reactive power compensation capacitor branch, photovoltaic inverter grid connection line, feeder segment switch section corresponding line reactance, line resistance and reactive current direction, calculate the reactance-resistance ratio and line impedance change rate of each line segment, determine the correspondence between reactive current direction and feeder current direction, record the reactive power feedback corresponding line segment, divide the line segment boundary according to the line impedance change threshold, establish the feeder level sequence number and the section correspondence, and generate the feeder impedance return boundary sequence; S3: Read the inverter reactive power output direction, feeder current propagation direction and inverter reactive power output capacity according to the feeder impedance foldback boundary sequence, identify the inconsistent direction section, lock the propagation section, and generate the inverter reactive power span locking section. S4: Based on the inverter reactive power span locking section, read the node voltage amplitude, line reactive power and line current, calculate the cumulative voltage drop on both sides of the turnaround boundary, identify the location and hierarchical mapping relationship of the section reactive power flow change, and generate the feeder reactive voltage coordinated section. S5: Based on the feeder reactive voltage coordination section, read the inverter node number, reactive output capacity and feeder voltage change direction, match the relationship between the level and the inverter span section, record the node positions of the inverter's allowed reactive power propagation section and prohibited reactive power propagation section, establish the section reactive power propagation sequence, and generate the active distribution network coordinated operation path.

2. The active power distribution network reactive power and voltage coordinated optimization operation method according to claim 1, characterized in that, The feeder voltage drop reversal distribution section includes the voltage drop reversal node, reactive power correlation direction, and line reversal range; the feeder impedance foldback boundary sequence includes the impedance change boundary, feeder level sequence number, and reactive power feedback section; the inverter reactive power span locking section includes the inverter propagation range, level capacity boundary, and direction conflict section; the feeder reactive power voltage coordination section includes the cumulative voltage drop area, reactive power flow location, and voltage coordination level; the active distribution network coordinated operation path includes the reactive power propagation sequence, inverter adjustment node, and feeder coordinated path.

3. The active power distribution network reactive power and voltage coordinated optimization operation method according to claim 1, characterized in that: The specific steps of dividing the line segment boundaries based on the line impedance change threshold include: pairing the line reactance and line resistance of two adjacent lines within the feeder voltage drop reversal distribution segment according to the same line level sequence number to obtain the reactance-resistance ratio and line impedance change rate of each line segment.

4. The active distribution network reactive power and voltage coordinated optimization operation method according to claim 3, characterized in that: When the line impedance change rate is greater than or equal to the line impedance change threshold, and the reactive current direction is opposite to the feeder current direction, the line section that meets the conditions is recorded as the reactive power feedback line section. The upstream and downstream endpoints of the reactive power feedback line segment are respectively used as the line segment boundaries, and the feeder impedance return boundary sequence is written according to the feeder level number and the segment correspondence.

5. The method for coordinated optimization of reactive power and voltage operation in active distribution networks according to claim 1, characterized in that, The specific steps of S1 are as follows: S101: Obtain the corresponding node voltage amplitude, line reactive power, and line current direction of the active distribution network feeder bus node, photovoltaic inverter access node, and low-voltage side node of the distribution transformer; call the feeder node voltage amplitude and line current direction to perform node correspondence processing; calculate the voltage drop change value of adjacent line sections according to the feeder topology relationship; establish the line section voltage drop change correspondence relationship; and generate the feeder voltage drop change sequence. S102: Based on the feeder voltage drop change sequence, call the line reactive power direction identifier, determine the order of voltage drop change direction of adjacent line sections, retrieve the line position corresponding to the change direction of voltage drop from load side to bus side, and associate and record the reactive power direction of the corresponding line section to obtain the voltage drop reversal section index set. S103: Based on the voltage drop reversal section index set, call the reactive power direction identifier of the corresponding line section, perform topology connection processing on the reversal line section, perform section merging according to the feeder node connection relationship, and uniformly mark the reactive power direction of each section to generate feeder voltage drop reversal distribution sections.

6. The method for coordinated optimization of reactive power and voltage operation in active distribution networks according to claim 1, characterized in that, The specific steps of S2 are as follows: S201: Based on the feeder voltage drop reversal distribution section, read the reactive power compensation capacitor branch, photovoltaic inverter grid connection line, feeder segment switch section corresponding line reactance, line resistance and reactive current direction, calculate the line reactance resistance ratio and line impedance change rate according to the line segment connection sequence, establish the line segment corresponding parameter mapping relationship, and generate the line impedance change sequence. S202: Based on the line impedance change sequence, call the reactive current direction and the feeder current direction to determine the correspondence between the current directions of the line sections, retrieve the corresponding line sections for reactive power feedback, and perform section boundary division in combination with the line impedance change threshold to obtain the impedance return boundary index set. S203: Based on the impedance return boundary index set, call the feeder level sequence number and line segment connection relationship, perform hierarchical classification processing on the boundary segments, establish the segment correspondence relationship according to the feeder topology order, and serialize and arrange each boundary segment to generate the feeder impedance return boundary sequence.

7. The method for coordinated optimization of reactive power and voltage operation in active distribution networks according to claim 1, characterized in that, The specific steps for S3 are as follows: S301: Based on the feeder impedance foldback boundary sequence, read the reactive power output direction, feeder current propagation direction, and reactive power output capacity of the photovoltaic inverter grid-connected node, feeder interconnection switch node, and distribution automation terminal node. According to the feeder hierarchy, determine the corresponding reactive power output direction and feeder current propagation direction, establish node direction association relationship, and generate inverter direction association sequence. S302: Based on the inverter direction association sequence, call the inverter reactive power output capacity and feeder node connection relationship, perform span search for line sections with inconsistent directions, and perform section filtering and determination according to the allowable reactive power capacity corresponding to the feeder level, record the corresponding inverter propagation range, and obtain the inverter propagation section index set. S303: Based on the inverter propagation segment index set, call the allowable reactive capacity of the feeder level and the connection relationship of the line segment, perform hierarchical classification processing on the inverter propagation segment, perform segment splicing according to the feeder topology order, and mark the propagation segment with a continuous sequence to generate the inverter reactive power span locking segment.

8. The method for coordinated optimization of reactive power and voltage operation in active distribution networks according to claim 1, characterized in that, The specific steps of S4 are as follows: S401: Based on the inverter reactive power span locking section, read the voltage amplitude, line reactive power and line current of the corresponding nodes of the feeder segment switch section, distribution transformer low voltage side node, reactive power compensation capacitor branch, and feeder segment voltage drop corresponding relationship, and generate feeder cumulative voltage drop sequence. S402: Based on the cumulative voltage drop sequence of the feeder, call the voltage drop propagation threshold and the reactive power of the line, determine the segment of the correspondence between the cumulative voltage drop value of the feeder and the voltage drop propagation threshold, retrieve the location of the reactive power flow change in the feeder segment, record the corresponding feeder level mapping relationship, and obtain the reactive power flow mapping index set; S403: Based on the reactive power flow direction mapping index set, call the feeder hierarchical mapping relationship and line section connection relationship, perform hierarchical classification processing on the reactive power flow direction change section, perform section association according to the feeder topology order, and mark the section as a continuous sequence to generate feeder reactive power voltage coordinated section.

9. The method for coordinated optimization of reactive power and voltage operation in an active distribution network according to claim 1, characterized in that, The specific steps of S5 are as follows: S501: Based on the feeder reactive voltage coordination section, read the photovoltaic inverter access node, feeder tie switch section, inverter node number corresponding to the distribution automation master station terminal, reactive output capacity, and feeder voltage change direction, match the feeder level sequence number with the inverter span section according to the feeder level order, establish the inverter section position mapping relationship, and generate the inverter section mapping sequence; S502: Based on the inverter section mapping sequence, call the reactive power output capacity and the direction of feeder voltage change, determine the section of the inverter that is allowed to propagate reactive power and the section that is prohibited from propagating reactive power, and record the corresponding node position and feeder level association relationship to obtain the reactive power propagation node index set. S503: Based on the reactive power propagation node index set, the feeder hierarchical association relationship and line segment connection relationship are called, the reactive power propagation order of the feeder segments is arranged, and the path association processing is performed according to the feeder topology connection order. The propagation segments are marked with continuous paths to generate an active distribution network collaborative operation path.

10. An active power distribution network reactive power and voltage coordinated optimization operation system, characterized in that, The system is used to implement the active power distribution network reactive power and voltage coordinated optimization operation method according to any one of claims 1-9, and the system includes: The voltage drop reversal module acquires the corresponding node voltage amplitude, line reactive power, and line current direction of the active distribution network feeder bus nodes, photovoltaic inverter access nodes, and low-voltage side nodes of distribution transformers. It calculates the voltage drop change value of the corresponding line section of adjacent feeder nodes, determines the voltage drop change direction of adjacent line sections, records the line position corresponding to the change direction of voltage drop from decreasing on the load side to decreasing on the bus side, and associates it with the reactive power direction of the corresponding line section to generate the feeder voltage drop reversal distribution section. The impedance boundary module reads the reactive power compensation capacitor branch, photovoltaic inverter grid-connected line, and feeder segment switch section corresponding line reactance, line resistance, and reactive current direction based on the feeder voltage drop reversal distribution section. It calculates the reactance-resistance ratio and line impedance change rate of each line section, determines the correspondence between the reactive current direction and the feeder current direction, records the line section corresponding to reactive power backfeed, divides the line section boundary according to the line impedance change threshold, establishes the correspondence between the feeder level sequence number and the section, and generates the feeder impedance back boundary sequence. The span locking module reads the reactive power output direction, feeder current propagation direction, and inverter reactive power output capacity corresponding to the photovoltaic inverter grid-connected node, feeder tie switch node, and distribution automation terminal node according to the feeder impedance foldback boundary sequence. It determines the correspondence between the inverter reactive power output direction and the feeder current propagation direction, records the inverter span sections corresponding to inconsistent directions, and locks the corresponding inverter propagation sections according to the allowable reactive power capacity at the feeder level, thus generating the inverter reactive power span locking section. The collaborative mapping module reads the voltage amplitude, line reactive power, and line current of the corresponding nodes of the feeder segment switch section, the low-voltage side node of the distribution transformer, and the reactive power compensation capacitor branch based on the inverter reactive power span locking section. It calculates the cumulative voltage drop value of the corresponding feeder on both sides of the turnback boundary, determines the correspondence between the cumulative voltage drop value of the feeder and the voltage drop propagation threshold, records the location of the reactive power flow change of the corresponding feeder section and the feeder level mapping relationship, and generates the feeder reactive power voltage collaborative section. The path generation module reads the photovoltaic inverter access node, feeder tie switch section, corresponding inverter node number of the distribution automation master station terminal, reactive power output capacity, and feeder voltage change direction according to the feeder reactive power voltage coordination section. It matches the correspondence between feeder level sequence number and inverter span section, records the node positions corresponding to the allowed reactive power propagation section and prohibited reactive power propagation section of each inverter, establishes the reactive power propagation sequence of the feeder section, and generates the active distribution network coordinated operation path.

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