A power distribution network load-carrying capacity quantitative evaluation method, system and terminal device

Abstract

This invention discloses a method, system, and terminal equipment for quantitatively assessing the carrying capacity of a distribution network, specifically relating to the field of power system regulation and control technology. It addresses the problem of overestimating carrying capacity due to neglecting the dynamic conflict between on-load tap-changing transformer operation and distributed generation voltage regulation. By real-time monitoring of the on-load tap-changing transformer's tap position operation status, it identifies local voltage exceedance events caused by distributed generation output increases. When a tap-down operation is triggered, it coordinates the integral value of the impact vibration envelope of the tap changer operation with the eddy current intensity distribution of the insulating oil flow field to determine the range of the voltage counter-regulation effect. Within this range, it detects the grounding current phase offset angle and determines whether it exceeds the tap changer insulation dielectric loss angle safety threshold. When it exceeds this threshold, it couples the tap position switching dynamic process with the phase offset constraint to quantify the voltage safety boundary compression ratio. Finally, it corrects the maximum connectable capacity based on this ratio and outputs the carrying capacity assessment result.

Description

Technical Field

[0001] This invention relates to the field of power system regulation and control technology, and more specifically, to a method, system, and terminal equipment for quantitatively assessing the carrying capacity of a distribution network. Background Technology

[0002] In the planning and operation of distribution networks, quantitatively assessing the access capacity of distributed generation requires determining the safety boundary based on the physical constraints of the power grid. Existing technologies calculate the maximum accessible capacity by establishing a static power grid model and verifying parameters such as line thermal stability and node voltage. This method assumes that the tap position of the on-load tap-changing transformer (OLTC) is fixed and its voltage regulation function is independent of the voltage regulation behavior of distributed generation.

[0003] Existing assessment methods ignore the dynamic conflict between OLTC action and distributed generation voltage regulation: when the output of distributed generation increases the local voltage, it triggers OLTC downshifting to maintain the voltage upper limit. However, the mechanical adjustment delay leads to excessive voltage adjustment, causing voltage instability in the remote load area. This causes the static model to overestimate the actual carrying capacity and cannot quantify the compression effect of OLTC action on the safety boundary, resulting in a serious deviation between the planning results and the actual operation. Summary of the Invention

[0004] In order to overcome the above-mentioned defects of the prior art, the present invention provides a method, system and terminal equipment for quantitatively evaluating the carrying capacity of a power distribution network to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for quantitatively assessing the carrying capacity of a power distribution network includes:

[0007] S1. Obtain the distribution network topology parameters and the location of distributed power source access;

[0008] S2. Based on the distribution network topology parameters and the location of distributed power source access, monitor the operation status of the on-load tap-changing transformer in real time to identify local voltage over-limit events caused by the increase in output of distributed power sources.

[0009] S3. When a local voltage over-limit event triggers a down-shifting operation, the integral value of the shock vibration envelope of the coordinated tap changer operation and the vortex intensity distribution of the insulating oil flow field determine the range of the voltage reverse regulation effect.

[0010] S4. Within the range of voltage reverse regulation effect, detect the phase offset angle of the grounding current injected by the distributed power source and determine whether the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer.

[0011] S5. When the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer, the dynamic process of coupling position switching and the phase offset constraint conditions are used to quantify the voltage safety boundary compression ratio.

[0012] S6. Correct the maximum accessible capacity according to the voltage safety boundary compression ratio, and output the load-bearing capacity assessment result.

[0013] Furthermore, the distribution network topology parameters and the location of distributed generation access are obtained, including:

[0014] The connection relationships and electrical parameters of the lines in the distribution network are obtained as the distribution network topology parameters. The distribution network topology parameters include line resistance, line reactance, and line-to-ground capacitance.

[0015] The specific node location of the distributed power source connected to the distribution network is obtained as the connection location of the distributed power source. The connection location of the distributed power source corresponds one-to-one with the node identifier in the distribution network topology parameters.

[0016] Establish a mapping relationship between distribution network topology parameters and the location of distributed power source access to form a basic dataset for dynamic analysis of the distribution network.

[0017] Furthermore, based on the distribution network topology parameters and the location of distributed power source access, the on-load tap-changing transformer tap position operation status is monitored in real time to identify local voltage over-limit events caused by the increase in distributed power source output, including:

[0018] Locate the node where the on-load tap-changing transformer is located and the node where the distributed power source is connected in the distribution network topology parameters;

[0019] Real-time acquisition of voltage values ​​at nodes where on-load tap-changing transformers are located and current output values ​​at nodes where distributed power sources are connected;

[0020] When the current output value of the node where the distributed power source is connected exceeds the historical benchmark output value and the duration reaches a preset threshold, it is determined that a distributed power source output increase has occurred.

[0021] The system synchronously monitors the changes in the tap position of the on-load tap-changing transformer. If the tap position is downshifting and the voltage value of the node where the transformer is located exceeds the upper voltage threshold, it is determined that a local voltage over-limit event has occurred due to the increase in the output of the distributed power source.

[0022] Furthermore, when a local voltage over-limit event triggers a down-tapping operation, the integral value of the shock vibration envelope of the coordinated tap changer operation and the eddy current intensity distribution of the insulating oil flow field determine the range of the voltage reversal effect, including:

[0023] When a local voltage over-limit event caused by a rise in the output of a distributed power source triggers a down-segment operation, the operation impact vibration waveform is collected at the moment the tap changer down-segmentes.

[0024] Envelope analysis is performed on the operational impact vibration waveform to extract the characteristic frequency band vibration energy envelope.

[0025] The integral value of the characteristic frequency band vibration energy envelope during the downshift operation duration is used as the integral value of the tap changer operation impact vibration envelope.

[0026] Simultaneously acquire image sequences of insulating oil flow field in the tap changer tank area;

[0027] The fluid velocity vector field was calculated based on the insulating oil flow field image sequence, and the maximum vortex intensity value and its spatial distribution were extracted.

[0028] Based on the mechanical impact energy propagation characteristics characterized by the integral value of the impact vibration envelope of the tap changer operation, and combined with the electromagnetic wave propagation medium state characterized by the maximum vortex intensity value of the insulating oil flow field, the range of voltage counter-regulation effect is calculated through the physical coupling effect of mechanical energy and fluid dynamic pressure.

[0029] Furthermore, within the range of voltage reverse regulation effect, the phase offset angle of the grounding current injected by the distributed power source is detected to determine whether the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer, including:

[0030] Locate the connection points of all distributed power sources within the range of voltage reverse regulation effect;

[0031] Real-time acquisition of the injected grounding current waveform and the reference waveform of the system neutral point voltage at each location of the distributed power supply access point;

[0032] The phase difference angle between the ground current waveform and the reference waveform of the system neutral point voltage is calculated as the phase offset angle of the ground current.

[0033] The standard dielectric loss tangent value of the tap changer insulation material is used as the safety threshold for the dielectric loss angle of the tap changer insulation.

[0034] The phase offset angle of the grounding current is numerically compared with the safety threshold of the insulation dielectric loss angle of the tap changer.

[0035] If the phase offset angle is greater than the safety threshold for the dielectric loss angle of the tap changer insulation, it is determined to exceed the safety threshold.

[0036] Furthermore, when the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer, the dynamic process of coupling tap switching and the phase offset constraint conditions, along with the quantified voltage safety boundary compression ratio, include:

[0037] The duration of the tap changer's gear switching action is obtained as a representation of the dynamic process of gear switching.

[0038] The excess value of the phase offset angle exceeding the safety threshold of the insulation dielectric loss angle of the tap changer is extracted as the quantitative parameter of the phase offset constraint condition;

[0039] Establish a physical correlation between the tap changer's tap position switching action duration and the excess value of the phase offset angle exceeding the safety threshold of the tap changer's insulation dielectric loss angle;

[0040] The weighting coefficient for the impact of tap changer position switching action duration on voltage safety boundary is determined based on physical correlation.

[0041] The influence weighting coefficients are applied to the static voltage safety boundary reference value to generate the voltage safety boundary compression ratio.

[0042] Furthermore, the physical correlation between the tap changer's position switching action duration and the phase offset angle exceeding the specified value is established through the following method:

[0043] Based on the correspondence records between gear shifting action duration and phase offset angle exceeding value in the historical fault database, a linear proportional mapping rule is established between the increase in action duration and the increase in phase offset exceeding value.

[0044] Furthermore, the maximum connectable capacity is corrected based on the voltage safety boundary compression ratio, and the output carrying capacity assessment results are given, including:

[0045] Obtain the baseline value of the maximum accessible capacity of the distribution network under static scenarios;

[0046] Extract the capacity correction factor characterized by the voltage safety boundary compression ratio;

[0047] The capacity correction factor is applied to the baseline value of the maximum accessible capacity of the distribution network under static scenarios to generate the dynamically corrected maximum accessible capacity value.

[0048] The carrying capacity assessment result is generated by comparing the maximum accessible capacity value after dynamic correction with the actual output value of distributed power sources.

[0049] On the other hand, the present invention provides a quantitative assessment system for the carrying capacity of a distribution network, comprising:

[0050] The parameter acquisition module is used to acquire distribution network topology parameters and the location of distributed power source access;

[0051] The over-limit identification module is used to monitor the tap position operation status of on-load tap-changing transformers in real time based on distribution network topology parameters and distributed power source access location, and to identify local voltage over-limit events caused by the increase in output of distributed power sources.

[0052] The reverse adjustment range module is used to determine the range of voltage reverse adjustment effect by coordinating the integral value of the impact vibration envelope of the tap changer operation with the eddy intensity distribution of the insulating oil flow field when a local voltage over-limit event triggers a down-shift operation.

[0053] The phase detection module is used to detect the phase offset angle of the grounding current injected by the distributed power source within the range of voltage reverse regulation effect, and to determine whether the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer.

[0054] The boundary compression module is used to couple the dynamic process of tap position switching with the phase offset constraint when the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer, and to quantify the voltage safety boundary compression ratio.

[0055] The capacity assessment module is used to correct the maximum accessible capacity according to the voltage safety boundary compression ratio and output the load capacity assessment result.

[0056] On the other hand, the present invention provides a terminal device, which includes a processor, a memory, and a program or instructions stored in the memory and executable on the processor. When the program or instructions are executed by the processor, a method for quantitatively assessing the carrying capacity of a power distribution network is implemented.

[0057] Compared with the prior art, the present invention has the following beneficial effects:

[0058] 1. By real-time monitoring of the dynamic interaction between the tap position operation status of the on-load tap-changing transformer and the output of distributed power sources, the coupling conflict mechanism between mechanical delay and electrical response during the tap-down operation of the on-load tap-changing transformer when the output of distributed power sources rises and triggers a local voltage over-limit event is revealed. By coordinating the integral value of the impact vibration envelope of the tap changer operation and the eddy intensity distribution of the insulating oil flow field, the spatial propagation range of the voltage reverse regulation effect is accurately quantified. This breaks through the simplified assumption in the traditional static model that the transformer regulation behavior and the distributed power source voltage regulation are independent of each other. By capturing the overshoot phenomenon in the voltage adjustment process, voltage instability in the remote load area caused by the regulation delay is avoided, and the technical blind spot of the static model overestimating the carrying capacity is eliminated.

[0059] 2. Based on the detection of the ground current phase offset angle within the range of voltage reverse regulation effect, and by associating the safety threshold of the insulation dielectric loss angle of the tap changer with the voltage safety boundary compression effect, the mechanical action characteristics are transformed into a quantifiable voltage safety boundary compression ratio by coupling the dynamic process of tap switching with the phase offset constraint. This achieves a dynamic mapping from the state of the insulation dielectric to the grid safety boundary. Finally, the maximum connectable capacity is corrected in real time based on the compression ratio, so that the carrying capacity assessment results synchronously reflect the time-varying compression effect of transformer operation on the grid safety boundary. This expands the traditional static safety boundary into a dynamic adjustable boundary, solves the contradiction between the planning results and the actual operation, and provides an accurate carrying capacity assessment framework for high-proportion distributed power access. Attached Figure Description

[0060] Figure 1This is a flowchart of a method for quantitatively evaluating the carrying capacity of a power distribution network according to the present invention;

[0061] Figure 2 This is a schematic diagram of the structure of a power distribution network carrying capacity quantitative assessment system according to the present invention. Detailed Implementation

[0062] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0063] Example 1: Figure 1 This invention provides a method for quantitatively assessing the carrying capacity of a distribution network, comprising:

[0064] S1. Obtain the distribution network topology parameters and the location of distributed power source access;

[0065] S2. Based on the distribution network topology parameters and the location of distributed power source access, monitor the operation status of the on-load tap-changing transformer in real time to identify local voltage over-limit events caused by the increase in output of distributed power sources.

[0066] S3. When a local voltage over-limit event triggers a down-shifting operation, the integral value of the shock vibration envelope of the coordinated tap changer operation and the vortex intensity distribution of the insulating oil flow field determine the range of the voltage reverse regulation effect.

[0067] S4. Within the range of voltage reverse regulation effect, detect the phase offset angle of the grounding current injected by the distributed power source and determine whether the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer.

[0068] S5. When the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer, the dynamic process of coupling position switching and the phase offset constraint conditions are used to quantify the voltage safety boundary compression ratio.

[0069] S6. Correct the maximum accessible capacity according to the voltage safety boundary compression ratio, and output the load-bearing capacity assessment result.

[0070] S1. Obtain the distribution network topology parameters and the location of distributed power source access. Specific implementation includes:

[0071] The specific implementation process for obtaining the line connection relationships and electrical parameters in the distribution network as distribution network topology parameters is as follows: The distribution network line ledger database is accessed in real time through the power grid dispatch automation system, and the measured electrical parameter records of each line segment are extracted from the database. Electrical parameters include line resistance, line reactance, and line-to-ground capacitance. Line resistance is measured using a DC resistance tester during power outage maintenance. The ambient temperature is corrected to a standard temperature of 20 degrees Celsius during measurement. For example, at an ambient temperature of 35 degrees Celsius, the measured resistance value is multiplied by a temperature correction factor to obtain the standard resistance value. Line reactance is calculated based on line geometric parameters combined with a conductor parameter library. The conductor parameter library pre-stores the inductive reactance per unit length for common conductor types; for example, the inductive reactance per unit length for 400 square millimeter steel-cored aluminum stranded wire is 0.3 ohms / km. The line-to-ground capacitance is measured using a distributed capacitance meter under energized conditions. The process involves injecting a 10 kHz high-frequency signal into the line and detecting the phase difference of the response current. The capacitance is calculated based on this phase difference; for example, a phase difference of 15 degrees corresponds to a capacitance of 0.02 microfarads. All electrical parameters are stored in a database according to line segment identifiers. Each record includes the line number, resistance value, reactance value, line-to-ground capacitance value, and a detection timestamp.

[0072] The specific implementation process for obtaining the exact node location of distributed power generation (DPG) access to the distribution network is as follows: First, the node coordinate data of the distribution network in the power grid geographic information system is read. This node coordinate data includes the latitude and longitude information of the power distribution equipment. Simultaneously, the access point coordinates of already connected power sources are obtained from the distributed power generation grid-connected management platform. These coordinates are collected on-site using GPS mapping equipment. Second, the distribution transformer node identifier is spatially matched with the DPG access point coordinates. The matching process calculates the straight-line distance. When the distance between the access point and the distribution transformer node is less than a set threshold (e.g., 50 meters), it is determined that the DPG is connected to this node, and an access location mapping table containing node number, power type, and installed capacity is generated.

[0073] The specific implementation process for establishing the association mapping relationship between distribution network topology parameters and distributed generation access locations is as follows: A data structure for the basic dataset of distribution network dynamic analysis is created. This data structure includes an association index between the topology parameter table and the access location table. The association index is implemented using the node number as the primary key. The node encoding rule is: area code plus node type code plus sequence number, for example, area code 1101 plus node type B plus sequence number 001203. The start and end node numbers of the lines in the line parameter table are matched with the node numbers in the access location table. Successfully matched records are merged into complete data entries. Data entries are stored in an in-memory database. Each entry contains a node number, line resistance value, line reactance value, line-to-ground capacitance value, access power type, and installed capacity. Association reconstruction is automatically triggered when data is updated. The reconstruction process includes incremental verification and topology connectivity verification. Topology connectivity verification ensures no isolated points by traversing all nodes.

[0074] The following is an example of the application of the basic dataset for dynamic analysis of distribution networks: Retrieving a data entry for a 10 kV feeder node, for example, the data corresponding to node number 1101B001203 includes: line resistance value 0.25 ohms, line reactance value 0.35 ohms, line-to-ground capacitance value 0.02 microfarads, and photovoltaic installed capacity 500 kilowatts.

[0075] Key parameter accuracy control implementation methods include: Line resistance measurement uses a four-wire connection method to eliminate contact resistance errors, retaining three significant figures; line reactance calculation incorporates temperature and humidity correction coefficients, for example, a correction coefficient of 1.05 at 70% relative humidity; ground capacitance testing uses a dual-frequency measurement method with weighted averages, for example, a weight of 0.7 for 10 kHz and 0.3 for 50 kHz. Distributed power source positioning accuracy is controlled within 0.1 meters.

[0076] The data anomaly handling process is as follows: When the line resistance value exceeds 10% of the theoretical maximum value of the same type of conductor (e.g., measured at 0.5 ohms while the theoretical upper limit is 0.4 ohms), the following processing procedure is executed: The three most recent historical records are retrieved. If the historical values ​​are consistently stable, the most recent valid value is adopted (e.g., 0.38 ohms); if no historical records are found, the average value of adjacent sections is taken (e.g., 0.36 ohms), and a maintenance warning is triggered. A temporary node number is added to the unmatched power supply access point, using a reserved coding segment (e.g., starting with 9000).

[0077] The storage implementation method for the basic dataset of power distribution network dynamic analysis is as follows: a block storage strategy is adopted, with each block having a fixed size of, for example, 8 megabytes. Line resistance values, reactance values, and capacitance values ​​to ground are stored as 32-bit floating-point numbers, and node numbers are stored as 12-byte fixed-length strings. The data index key is the node number prefix code (e.g., 1101B).

[0078] The data validation process includes: daily scanning of non-empty fields and numerical ranges (e.g., resistance value > 0); weekly verification of topological connectivity; and monthly backup of 12 copies. A backup database is switched on if three consecutive validations fail.

[0079] S2. Based on the distribution network topology parameters and the location of distributed power source access, monitor the tap position operation status of on-load tap-changing transformers in real time to identify local voltage over-limit events caused by the increase in output of distributed power sources. Specific implementation includes:

[0080] The specific implementation process for locating the nodes containing on-load tap-changing transformers and the nodes where distributed generation (DG) sources are connected in the distribution network topology parameters is as follows: A list of node numbers is read from the distribution network dynamic analysis basic dataset. Node numbers use a unified coding rule, for example, area code 1101 plus node type code B plus serial number 001203. Nodes with node type code 'T' are identified as nodes containing on-load tap-changing transformers, and nodes with node type code 'G' and a non-empty power source type field are identified as nodes where DG sources are connected. The location process is implemented through database queries, with the query condition set to the node type field equal to a specific code value. For example, the query for the node containing the on-load tap-changing transformer is SELECT node_number FROM basic_dataset WHERE node_type='T'. The location results generate two node mapping tables: the on-load tap-changing transformer node table contains the node number and its associated feeder information, and the DG source connection node table contains the node number, power source type, and installed capacity.

[0081] The specific implementation process for real-time acquisition of voltage values ​​at nodes where on-load tap-changing transformers are located and current output values ​​at nodes where distributed power sources are connected is as follows: For each located node where an on-load tap-changing transformer is located, real-time voltage waveforms are acquired using voltage sensors installed at that node. The voltage sensors employ voltage transformers with a precision of 0.2 class, and the acquisition frequency is 80 sampling points per second. The acquired data is transmitted to the data processing unit via an optical fiber communication network. The data processing unit filters the original waveform using a 50 Hz bandpass filter to eliminate high-frequency interference, and then calculates the effective voltage value for each power frequency cycle, for example, calculating the root mean square value of the voltage within a 20-millisecond window. For nodes where distributed power sources are connected, instantaneous three-phase current and voltage values ​​are acquired using smart meters. The current measurement accuracy is 0.5 class. Real-time output power is calculated based on the instantaneous values, using the formula P = Ua × Ia + Ub × Ib + Uc × Ic, where Ua, Ub, and Uc are the instantaneous phase voltage values, and Ia, Ib, and Ic are the instantaneous phase current values. The calculation results are updated every 200 milliseconds and stored in the power output table of the real-time database.

[0082] When the current output value of the node where the distributed power source is connected exceeds the historical baseline output value and the duration reaches a preset threshold, the specific implementation process for determining a distributed power source output increase is as follows: The historical baseline output value is calculated by statistically analyzing output data from the same time period over the past 30 days. For example, the average output value from 9:00 to 10:00 AM daily is used as the baseline value for that period, and the statistical period covers day and night cycles as well as weather change cycles. The comparison between the current output value and the historical baseline output value adopts a sliding window mechanism, with a window duration set, for example, 5 minutes. Within the window duration, if the current output value continuously exceeds the baseline value, an output increase flag is triggered. The duration threshold is set according to the power source type; for example, 10 minutes for photovoltaic power and 15 minutes for wind turbine power. The determination logic is implemented through a state machine, which includes three states: normal state, warning state, and increase state. When the output value continuously exceeds the baseline value and reaches the threshold, the system transitions to the increase state and generates an event record.

[0083] The specific implementation process for synchronously monitoring the tap position operation status changes of the on-load tap-changing transformer is as follows: If the tap position operation status is a downshift and the voltage value of the node where the transformer is located exceeds the upper voltage threshold, a local voltage over-limit event caused by the output increase of distributed generation is determined. Tap position operation status monitoring is achieved through tap changer position sensors, with the sensor outputting a 4-20 mA analog signal corresponding to 17 tap positions. Tap position change detection uses a method of comparing tap values ​​in adjacent sampling periods. When the tap value changes and the change exceeds one tap, a tap position operation event is recorded. The upper voltage threshold is obtained by multiplying the transformer's rated voltage by a coefficient, with the coefficient ranging from 1.05 to 1.10 (e.g., 10.7 kV for a 10 kV transformer). Event determination requires the simultaneous fulfillment of three conditions: the presence of a distributed generation output increase event flag, the tap position operation direction being a downshift, and the voltage value of the node where the on-load tap-changing transformer is located exceeding the upper voltage threshold. The judgment process is completed within a 200-millisecond time window. The event log includes a timestamp, the on-load tap-changing transformer node number, the associated distributed power source node number, the tap change value, and the voltage exceedance value.

[0084] The specific implementation methods for setting key parameters include: adjusting the voltage upper limit threshold coefficient according to the line length, with the coefficient increasing by 0.01 for every 5 kilometers of line length increase. The duration threshold is dynamically adjusted in wind turbine power supply scenarios; when the wind speed change rate exceeds 1 meter per second, the threshold is shortened to, for example, 8 minutes. A 50-millisecond delay is set for gear change detection to eliminate mechanical vibration interference.

[0085] The data acquisition accuracy assurance process is as follows: The voltage acquisition channel undergoes daily zero-point drift calibration. The calibration process involves shorting the input terminal, recording the offset, and storing the compensation value. Current acquisition employs temperature compensation technology; when the temperature change exceeds 5 degrees Celsius, the turns ratio is automatically adjusted. A harmonic filtering stage is added to the output calculation to remove higher-order harmonic components.

[0086] The event judgment and anomaly handling implementation methods include: when voltage acquisition is abnormal, initiating backup voltage source switching, with the backup voltage source taken from the voltage transformer of the adjacent node. When the tap position signal is lost, judgment is aided by vibration sensors, detecting the vibration characteristic waveform of the tap changer mechanism. For missing historical reference values, data interpolation from adjacent dates and time periods is used.

[0087] The local voltage over-limit event log storage structure is implemented as follows: binary format is used for storage, with fields including event type code, timestamp, on-load tap-changing transformer node number, distributed power source node number, previous tap value, subsequent tap value, and peak voltage. Storage files are archived by feeder partition, with each file containing 24 hours of event records. Event log transmission uses a communication protocol with retransmission mechanism.

[0088] The event judgment logic verification implementation process includes: weekly simulation tests to inject simulated signals, and monthly on-site comparison tests to calibrate the judgment threshold. The judgment results generate a statistical report including the number of events and the extent of exceedance.

[0089] S3. When a local voltage over-limit event triggers a down-tapping operation, the integral value of the shock vibration envelope of the coordinated tap changer operation and the eddy current intensity distribution of the insulating oil flow field determine the range of the voltage reversal effect. Specific implementation includes:

[0090] When a local voltage over-limit event triggered by a distributed power supply output surge causes a tap changer to downshift, the specific implementation process for acquiring the impact vibration waveform at the moment of tap changer downshift is as follows: Within 500 milliseconds of the local voltage over-limit event trigger, a vibration acceleration sensor installed on the tap changer mechanism box is activated to acquire the vibration waveform. The vibration acceleration sensor is a piezoelectric triaxial sensor with a range set to, for example, ±50g and a sampling frequency of, for example, 10 kHz. The acquisition time window covers the entire downshift operation process, for example, from 100 milliseconds before the tap change begins to 200 milliseconds after the tap change stabilizes. The sensor signal is transmitted to the signal conditioning unit via a shielded cable. The acquisition is triggered by the simultaneous detection of the local voltage over-limit event flag and the tap changer position sensor's downshift initiation signal.

[0091] The specific implementation process for extracting the characteristic frequency band vibration energy envelope from the operational impact vibration waveform is as follows: First, the original vibration waveform is bandpass filtered, with the filtering frequency band set to, for example, 1 kHz to 3 kHz. The filtered signal is then transformed to obtain the analytic signal; the amplitude component of the analytic signal is the vibration envelope. The characteristic frequency band vibration energy envelope is extracted using root mean square calculation with a sliding window, with the window width set to, for example, 10 milliseconds. The envelope data is stored in time series.

[0092] The specific implementation process for calculating the integral value of the characteristic frequency band vibration energy envelope during the downshift operation duration as the integral value of the tap changer operation impact vibration envelope is as follows: The downshift operation duration is determined by the tap changer position sensor. The integration calculation uses a numerical integration method, with an integration step size of, for example, the sampling interval of 0.1 milliseconds. The integral value is calculated by multiplying the cumulative value of the characteristic frequency band vibration energy envelope at all sampling points during the duration by the step size. For example, if the duration is 200 milliseconds and contains 2000 sampling points, the integral value is the sum of the envelope values ​​at each point multiplied by 0.0001 seconds. The unit of the integration result is acceleration multiplied by time.

[0093] The specific implementation process for synchronously acquiring the insulating oil flow field image sequence in the tap changer tank area is as follows: A high-speed camera is installed at the observation window of the tap changer tank, with the frame rate set to, for example, 2000 frames per second. The acquisition timing is synchronized with the vibration waveform acquisition. The image sequence acquisition duration covers the entire downscaling operation process plus a buffer period, for example, a total duration of 300 milliseconds. Each frame of the image is marked with a precise timestamp.

[0094] The specific implementation process for calculating the fluid velocity vector field and extracting the maximum vortex intensity value and its spatial distribution based on the image sequence of insulating oil flow field is as follows: Displacement analysis is performed on two consecutive frames of images, with the analysis window size set to, for example, 32×32 pixels. The displacement vector is calculated using a pixel displacement calculation method. The velocity vector field is obtained by dividing the displacement vector by the inter-frame time interval. The vortex intensity is calculated using a velocity rotation method, calculating the local vortex value at each grid point. The maximum vortex intensity value is obtained by comparing the vortex data across the entire field. The spatial distribution is recorded as a set of coordinates of regions where the vortex is greater than a specific proportion of the maximum vortex intensity value; this specific proportion is set to, for example, 80%.

[0095] Based on the mechanical impact energy propagation characteristics characterized by the integral value of the tap changer operation impact vibration envelope, and combined with the electromagnetic wave propagation medium state characterized by the maximum vortex intensity value of the insulating oil flow field, the specific implementation process for calculating the range of the voltage reverse regulation effect through the physical coupling of mechanical energy and fluid dynamic pressure is as follows: Establish the physical coupling relationship between mechanical impact energy and oil flow vortex intensity. The radius of the voltage reverse regulation effect's range is proportional to the product of the mechanical impact energy coefficient and the vortex intensity coefficient. The mechanical impact energy coefficient is calculated by dividing the integral value of the tap changer operation impact vibration envelope by a reference integral value, which is determined through testing, for example, 0.5 times the acceleration multiplied by the time unit. The vortex intensity coefficient is calculated by dividing the maximum vortex intensity value of the insulating oil flow field by a reference vortex intensity value, which is measured under static conditions, for example, 10 radians per second. The range is defined as a spherical region with the tap changer as its center.

[0096] The key parameter calibration implementation methods include: determining the characteristic frequency band through impact testing; calibrating the vortex intensity benchmark value using a flow velocity measurement device; and obtaining the proportionality coefficient in the radius of action calculation formula from historical cases, for example, a mechanical impact energy coefficient of 1.2 corresponds to a 20% increase in the radius of action.

[0097] The synchronous control implementation process of the acquisition system is as follows: a clock source is used to provide a unified time base, with a clock accuracy of, for example, 100 nanoseconds. Vibration acquisition and image acquisition trigger signals are transmitted via optical fiber.

[0098] The abnormal data processing implementation methods include: activating the automatic range switching function when the vibration signal is saturated; employing adjacent frame interpolation compensation when motion blur occurs in image acquisition; and setting the outlier filtering rule for vortex intensity calculation to consider data points exceeding a specific multiple of the theoretical maximum value as invalid, with the specific multiple set to, for example, 3 times.

[0099] The output implementation of the voltage inversion effect range is as follows: the effective radius value is accurate to 0.1 meters, and the spatial distribution coordinate set uses three-dimensional grid encoding, with a grid size of, for example, 0.5 meters by 0.5 meters by 0.5 meters. The output data includes the effective radius value and a spatial distribution map.

[0100] The verification method implementation process includes: conducting monthly simulation tests to measure the deviation between the actual impact range and the calculated value. The calculated impact range is compared with fault data, and a calibration process is triggered when the deviation exceeds a set threshold, which is set, for example, 20%.

[0101] S4. Within the range of voltage reverse regulation effect, detect the phase offset angle of the grounding current injected by the distributed power source, and determine whether the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer. Specific implementation includes:

[0102] The specific implementation process for locating the connection locations of all distributed power sources within the voltage inversion effect range is as follows: The spatial coordinate data of the voltage inversion effect range is read. This data is a three-dimensional grid map, with a grid size of, for example, 0.5m × 0.5m × 0.5m. The coordinates of the distributed power source connection locations in the distribution network dynamic analysis basic dataset are spatially matched with the grid of the effect range. The matching algorithm calculates the spatial distance from the power source coordinates to the center point of the effect range. When the distance is less than the effect radius, the distributed power source is determined to be within the effect range. For example, when the effect radius is 15 meters, power sources with a distance less than 15 meters are located. The location results generate a list of power source node numbers. Each node number is associated with its spatial coordinates and electrical parameters. The coordinate matching process considers the influence of terrain elevation differences. When the elevation difference exceeds, for example, 10 meters, the effect radius is reduced by 0.5% per meter of difference.

[0103] The specific implementation process for real-time acquisition of the injected grounding current waveform and the system neutral point voltage reference waveform at each location of the distributed power supply access point is as follows: For each location node, the injected grounding current waveform is acquired through a zero-sequence current transformer. The current transformer ratio is set to, for example, 1000:1, and the sampling frequency is set to, for example, 10 kHz. The system neutral point voltage reference waveform is obtained through the secondary side of a voltage transformer, whose primary side is connected to the neutral point of the transformer's star winding. Acquisition synchronization is ensured by a clock source, with time synchronization accuracy controlled within, for example, 1 microsecond. The grounding current waveform acquisition duration is two power frequency cycles after the downsizing operation, for example, 40 milliseconds, and the waveform data is stored at 12-bit resolution. The acquisition channel is configured with a 50 Hz notch filter, with an attenuation factor set to, for example, 60 dB. The voltage reference channel adds a common-mode rejection circuit, with a common-mode rejection ratio greater than, for example, 120 dB.

[0104] The specific implementation process for calculating the phase difference angle between the grounding current waveform and the system neutral point voltage reference waveform as the phase offset angle of the grounding current is as follows: First, align the zero-time points of the two waveforms, using the positive zero-crossing point of the voltage reference waveform as the alignment reference. Within a 5-cycle window (e.g., 100 milliseconds), extract the fundamental component of the grounding current and the fundamental component of the voltage reference waveform. The phase difference is calculated using the zero-crossing detection method: identify the positive zero-crossing time values ​​of the voltage waveform and the current waveform respectively. The phase difference angle is equal to the time difference divided by the waveform period and then multiplied by 360 degrees. For example, if the measured time difference is 0.5 milliseconds and the power frequency period is 20 milliseconds, then the phase offset angle is (0.5 / 20) × 360 = 9 degrees. The calculation result is accurate to 0.1 degrees. The calculation process is implemented using a hardware timer with a reference clock frequency of, for example, 100 MHz and a time resolution of 10 nanoseconds.

[0105] The specific implementation process for obtaining the standard dielectric loss tangent value safety threshold of the tap changer insulation material as the safety threshold of the tap changer insulation dielectric loss angle is as follows: Access the pre-stored tap changer insulation material technical manual database. The database structure includes a tap changer model field, an insulation material type field, and a standard dielectric loss tangent value field. Based on the current tap changer model identifier, such as model code OLTC-2024, query matching records and extract the standard dielectric loss tangent value safety threshold. This value is a material characteristic constant; for example, 0.005 corresponds to epoxy resin material. Convert the tangent value into an angle value as the safety threshold. The conversion process is implemented using a lookup table, storing the angle values ​​corresponding to tangent values ​​from 0 to 0.01, with a step size of 0.0001. For example, a tangent value of 0.005 corresponds to a 0.286-degree angle safety threshold.

[0106] The specific implementation process of comparing the phase offset angle of the grounding current with the safety threshold of the tap changer insulation dielectric loss angle is as follows: A comparator circuit is established. Input A is connected to the digital signal of the phase offset angle, for example, 9.0 degrees. Input B is connected to the digital signal of the safety threshold of the tap changer insulation dielectric loss angle, for example, 0.286 degrees. The comparator outputs a high level when the input value of A is greater than the input value of B. The comparison result generates a Boolean flag signal, and the actual difference is recorded, for example, 9.0 - 0.286 = 8.714 degrees. The comparison process is executed every 200 milliseconds. If three consecutive comparisons are true, a judgment is triggered. The judgment time is set to, for example, 600 milliseconds.

[0107] If the phase offset angle exceeds the safety threshold for the tap changer's insulation dielectric loss angle, the specific implementation process for determining that the safety threshold has been exceeded is as follows: When the comparator output remains high for the determination duration, a safety threshold over-limit event record is generated. The event record includes the over-limit node number, the measured value of the phase offset angle, the safety threshold for the tap changer's insulation dielectric loss angle, and the over-limit start timestamp. The determination result is transmitted to the protection system through the digital signal output interface, simultaneously triggering the local alarm indicator. The event record uses a structured data format, with fields including event number, node number, phase offset angle, safety threshold for the tap changer's insulation dielectric loss angle, and timestamp.

[0108] The specific implementation process for calling the standard dielectric loss tangent value data table pre-stored in the tap changer insulation material technical manual is as follows: The technical manual database is stored in a read-only memory chip. The data table structure is a two-dimensional relational table, with the row index being the tap changer model code. The column fields include material name, test temperature, and standard dielectric loss tangent value. The query command is sent via a serial communication interface, containing a 16-bit model identification code. The returned data packet contains a 32-bit floating-point tangent value; for example, model code 0x5A2B returns 0.005. The data table update mechanism involves writing new version data via a dedicated programmer while the power is off, with the update cycle set to, for example, once every two years.

[0109] The anomaly handling mechanism includes the following steps: When the clock signal is lost, switching to the backup clock source is initiated, with a clock drift compensation value of 0.1 seconds per day (daily error correction). If a database query fails, the default tap changer insulation loss angle safety threshold of 0.3 degrees is activated, and a maintenance request is issued. If the phase difference calculation result is abnormal, such as greater than 90 degrees, the backup calculation channel is activated for re-acquisition. Signal transmission uses twisted-pair shielded cable, with the shield grounded at the nearest grounding point to the acquisition point, and the grounding resistance less than, for example, 1 ohm.

[0110] The output of the judgment result is implemented as follows: Over-limit event records are stored in a circular buffer with a depth of, for example, 1000 records, covering the event records of the most recent 10 minutes. Real-time comparison results are output via an analog signal of 4 to 20 mA, with 20 mA corresponding to the over-limit state. The data storage format uses a time-series database, stored in minute-by-minute chunks, with each chunk approximately 50 kilobytes in size. The output interface is configured with opto-isolation protection, with the isolation voltage set to, for example, 2500 volts.

[0111] The verification process includes: quarterly phase calibration tests, using a standard phase source to inject a known phase difference signal, verifying that the measurement error is less than, for example, 0.5 degrees. Annually, the technical manual database version is compared with the equipment nameplate parameters to ensure data consistency. Monthly grounding loop impedance tests are performed to ensure that the grounding resistance is less than, for example, 0.5 ohms. Field verification uses a simulated grounding fault generator to inject a controllable phase offset current to verify the accuracy of the judgment logic.

[0112] S5. When the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer, the dynamic process of coupling tap switching and the phase offset constraint conditions are used to quantify the voltage safety boundary compression ratio. Specific implementation includes:

[0113] The specific implementation process for obtaining the tap changer gear shifting action duration as a characterizing quantity of the dynamic process of gear shifting is as follows: The start and end times of gear shifting are recorded using a tap changer position sensor. The start time is determined by a change in the gear value for two consecutive sampling periods, and the end time is determined by a stable gear value for, for example, 10 consecutive sampling periods. The action duration is calculated by subtracting the start time from the end time, with the time difference accurate to the millisecond level. For example, if the start time is measured to be 10:05:30.500 and the end time to be 10:05:31.200, the action duration is 700 milliseconds. The sensor sampling period is set to, for example, 100 milliseconds to ensure complete capture of the switching process. The action duration data is stored in an action duration record table in a real-time database. Each record includes a timestamp, tap changer number, and tap changer gear shifting action duration value.

[0114] The specific implementation process for extracting the excess value of the phase offset angle exceeding the safety threshold of the tap changer insulation dielectric loss angle as a quantitative parameter of the phase offset constraint is as follows: The measured value of the phase offset angle and the safety threshold of the tap changer insulation dielectric loss angle are read from the safety threshold exceedance event record. The excess value is calculated as the difference between the measured value and the safety threshold. For example, if the measured phase offset angle is 9.0 degrees and the safety threshold is 0.286 degrees, the excess value is 8.714 degrees. The calculation process is executed immediately after the event is determined, and the excess value is accurate to 0.01 degrees. The excess value data is associated with the corresponding gear switching event, and the stored fields include the event number, the excess value of the phase offset angle, and the associated tap changer number. The data verification mechanism includes a range check; when the excess value is less than 0 or greater than, for example, 90 degrees, it is marked as abnormal data.

[0115] The specific implementation process for establishing the physical correlation between the tap changer shifting action duration and the phase offset angle exceeding value is as follows: Access the historical fault database. The database storage structure includes fields for tap changer shifting action duration, phase offset angle exceeding value, and fault level. Establish a linear proportional mapping rule based on historical records: the increase in the phase offset angle exceeding value is equal to the increase in the tap changer shifting action duration multiplied by a proportional coefficient. The proportional coefficient is determined through historical data fitting analysis. For example, analyzing 100 sets of historical records yields a proportional coefficient of 0.02 degrees per millisecond, indicating that for every 1 millisecond increase in the tap changer shifting action duration, the phase offset angle exceeding value increases by 0.02 degrees. The mapping rule is stored as a two-dimensional lookup table. The horizontal axis represents the tap changer shifting action duration value, ranging from, for example, 200 milliseconds to 1000 milliseconds, and the vertical axis represents the phase offset angle exceeding value, ranging from, for example, 0 degrees to 20 degrees.

[0116] The specific implementation process for determining the weighting coefficient of the influence of tap changer position switching action duration on the voltage safety boundary based on physical correlation is as follows: The influence weighting coefficient is equal to the ratio of the tap changer position switching action duration to the reference duration multiplied by the ratio of the phase offset angle excess value to the reference excess value. The reference duration is taken as the rated action duration of the tap changer, for example, 500 milliseconds; the reference excess value is taken as a specific multiple of the safety threshold, for example, 2 times, i.e., 0.572 degrees. The specific calculation is: Influence weighting coefficient = (Measured action duration / 500 milliseconds) × (Measured excess value / 0.572 degrees). For example, if the measured action duration is 700 milliseconds and the excess value is 8.714 degrees, then the influence weighting coefficient = (700 / 500) × (8.714 / 0.572) = 2.5 × 15.24 = 38.1. The calculation result is rounded to one decimal place.

[0117] The specific implementation process for applying the influence weighting coefficient to the static voltage safety boundary benchmark value to generate the voltage safety boundary compression ratio is as follows: The static voltage safety boundary benchmark value is taken from the upper limit value specified in the distribution network operation regulations, for example, 10.7 kV for a 10 kV system. The voltage safety boundary compression ratio is calculated using a segmented rule: when the influence weighting coefficient is less than or equal to 1, the voltage safety boundary compression ratio is 0; when the influence weighting coefficient is greater than 1 and less than or equal to 30, the voltage safety boundary compression ratio = 0.01 × influence weighting coefficient; when the influence weighting coefficient is greater than 30, the voltage safety boundary compression ratio is fixed at 0.3. For example, an influence weighting coefficient of 38.1 corresponds to a voltage safety boundary compression ratio of 0.3. The voltage safety boundary compression ratio value is stored in the safety boundary correction table, and a voltage safety boundary compression ratio record is generated simultaneously. The record includes the voltage safety boundary compression ratio value, calculation time, and associated event number.

[0118] The implementation method for constructing the historical fault database includes: the database records fault events within a specific time period, such as the past five years. Each record includes the duration of tap changer position switching, the excess value of the phase offset angle, and the severity of the fault consequence. The proportional coefficient update mechanism recalculates the coefficient every time a certain number of valid records are added; for example, every 50 new records are added, the proportional coefficient is updated using a data fitting method. The lookup table is updated at a fixed period, such as quarterly. New data points must pass quality verification, and the verification rule is that the duration of tap changer position switching and the excess value of the phase offset angle must satisfy a positive correlation.

[0119] The abnormal data handling process is as follows: When the tap changer's position switching action duration exceeds a reasonable range, such as greater than 2000 milliseconds, it is considered mechanical fault data, and the backup mapping rule is activated: the phase offset angle exceeding the value is taken as the historical average, for example, 8 degrees. When the proportional coefficient calculation results in a negative value, it is forcibly reset to zero and a system alarm is triggered. A limiting protection is added to the calculation of the weighting coefficient, with the upper limit set to, for example, 100, to prevent calculation overflow. When the static voltage safety boundary reference value is missing, the default value of the same voltage level is called.

[0120] The verification method implementation process includes: monthly sampling of a specific percentage of historical events to recalculate the voltage safety boundary compression ratio, for example, 10%, with the deviation compared to the original records needing to be less than a specific threshold, such as 5%. Quarterly dynamic simulation tests are conducted: different tap changer switching action durations are set on the test tap changer, such as 300 milliseconds, 600 milliseconds, and 900 milliseconds, injecting corresponding phase offset angle excess values, such as 6 degrees, 12 degrees, and 18 degrees, and measuring the actual voltage safety boundary compression. When the deviation between the test result and the calculated result exceeds a specific threshold, such as 10%, the mapping rule calibration process is triggered. The calibration process includes refitting the scaling factor and updating the lookup table.

[0121] The implementation method for the voltage safety boundary compression ratio is as follows: The voltage safety boundary compression ratio value is output to the distribution network monitoring system, and the system automatically generates a new voltage upper limit value. The new upper limit value = static reference value × (1 - compression ratio). For example, if the static reference value is 10.7 kV and the voltage safety boundary compression ratio is 0.3, then the new upper limit value is 7.49 kV. The voltage safety boundary compression ratio record is stored for a specific period, such as one year, in a time-series database format, supporting retrieval by feeder partition. Data storage adopts a dual backup mechanism, with the primary and backup databases synchronized in real time, and the synchronization time difference is less than a specific value, such as 50 milliseconds.

[0122] The fault tolerance mechanism for key parameters includes: when the calculation of the weighting coefficient is abnormal, such as when the division by zero, a fixed voltage safety boundary compression ratio is enabled, for example, 0.2. The voltage safety boundary compression ratio output is processed with a smoothing filter, using a moving average algorithm, with a window size of, for example, 5 consecutive calculated values, to avoid abrupt changes in the result. The data communication interface is configured with an error check code, using cyclic redundancy check (CRC) as the check polynomial, and a specific standard, such as CRC-16.

[0123] S6. Correct the maximum accessible capacity according to the voltage safety boundary compression ratio, and output the load-bearing capacity assessment result. Specific implementation includes:

[0124] The specific implementation process for obtaining the baseline value of the maximum accessible capacity of the distribution network under static scenarios is as follows: The baseline value of the maximum accessible capacity of the distribution network under static scenarios comes from pre-stored data in the distribution network planning database. This database stores the carrying capacity limit values ​​of each feeder segment under standard operating conditions. Standard operating conditions are defined as the ideal operating state with an ambient temperature of, for example, 25 degrees Celsius, a line load factor of, for example, 80%, and a power factor of, for example, 0.95. The baseline value is generated through offline power flow calculation. The calculation method is to gradually increase the output of distributed power sources until the voltage of key nodes reaches the upper limit threshold, for example, the total capacity value corresponding to the upper limit of the 10 kV system voltage of, for example, 10.7 kV. The database record contains the feeder number, the baseline value, and the calculation timestamp. For example, the baseline value of feeder F01 is, for example, 5 MW. Data retrieval is implemented through a standard application programming interface (API). The input parameters of the interface are the feeder number and voltage level, and the output is a 32-bit floating-point capacity value.

[0125] The specific implementation process for extracting the capacity correction coefficient, which is characterized by the voltage safety boundary compression ratio, is as follows: The capacity correction coefficient is defined as 1 minus the voltage safety boundary compression ratio. The voltage safety boundary compression ratio is taken from the latest record in the safety boundary correction table, which stores the most recently calculated voltage safety boundary compression ratio values ​​in reverse chronological order. For example, when the voltage safety boundary compression ratio is read as 0.3, the capacity correction coefficient is calculated as 1 - 0.3 = 0.7. The extraction process includes data validity verification. When the voltage safety boundary compression ratio is less than 0 or greater than 1, the default value of 0 is enabled, corresponding to a capacity correction coefficient of 1. A data association mechanism ensures the correspondence between the correction coefficient and the target feeder, and an index is established through the feeder number field.

[0126] The specific implementation process for generating a dynamically corrected maximum access capacity value by applying a capacity correction factor to the static maximum access capacity benchmark value of the distribution network is as follows: The dynamically corrected maximum access capacity value is equal to the static maximum access capacity benchmark value of the distribution network multiplied by the capacity correction factor. The calculation process is completed in the data processor. For example, the static maximum access capacity benchmark value of the distribution network is 5 MW, multiplied by the capacity correction factor of 0.7 to obtain a dynamically corrected maximum access capacity value of 3.5 MW. The calculation result is added with a time stamp and feeder identifier and stored in the dynamic capacity table of the real-time database. The calculation is triggered by the voltage safety boundary compression ratio update event, and the event response delay is controlled within, for example, 100 milliseconds. The calculation result is smoothed using a moving average algorithm, and the average of the three most recent calculation values ​​is taken as the final output value.

[0127] The specific implementation process for generating a carrying capacity assessment result based on the comparison between the dynamically corrected maximum accessible capacity and the actual output of distributed generation is as follows: The actual output of distributed generation is acquired in real time through the distribution network monitoring system, with a data sampling interval of, for example, 1 second. The comparison process uses difference calculation: the margin value equals the dynamically corrected maximum accessible capacity minus the actual output value. The carrying capacity assessment result is graded according to the percentage of the margin value: when the margin value is greater than, for example, 20% of the dynamically corrected maximum accessible capacity, the assessment result is "ample"; when the margin value is between, for example, 5% and 20%, it is "critical"; when the margin value is less than, for example, 5%, it is "overloaded". For example, if the dynamically corrected maximum accessible capacity is, for example, 3.5 MW, the actual output is, for example, 3.3 MW, the margin is 0.2 MW, the proportion is, for example, 5.7%, and the assessment result is "critical". The assessment result generates a structured data packet containing a timestamp, feeder number, margin value, and assessment level field.

[0128] The implementation methods for handling key parameters include: In static scenarios, the update mechanism for the maximum accessible capacity benchmark value of the distribution network is set to automatically overwrite the old value with the latest planning data every quarter. A range constraint is added to the capacity correction coefficient, with an upper limit fixed at 1.0 and a lower limit set, for example, 0.5. After dynamic correction, the maximum accessible capacity value output is configured with amplitude limiting protection; when the calculated result exceeds, for example, 120% of the maximum accessible capacity benchmark value of the distribution network in static scenarios, it is forcibly reverted to the benchmark value.

[0129] The anomaly handling process is as follows: When the voltage safety boundary compression ratio is missing, the capacity correction factor is set to 1.0 by default. In static scenarios, if the maximum accessible capacity benchmark value for the distribution network fails to be retrieved, a typical value of the same voltage level is used; for example, 4 MW for a 10 kV feeder. When the actual output value is abnormal, the average value over a specific previous time period is used instead, such as the average value of the previous 5 minutes. When a negative value appears in the margin calculation, the assessment result is forced to be "overload," and an alarm is triggered.

[0130] The load-bearing capacity assessment results are output as follows: the assessment level is displayed via indicator lights on the human-machine interface, with green corresponding to "ample," yellow to "critical," and red to "overload." Data packets are transmitted to the upper-level system via a message queue. Historical assessment results are stored in a time-series database with a retention period of, for example, one year, and can be retrieved by time range.

[0131] The verification process includes: daily comparison of the maximum accessible capacity benchmark value of the distribution network under static scenarios with the offline calculation results; issuing a data anomaly alarm when the deviation exceeds, for example, 5%. Monthly verification of the correction logic: setting a known voltage safety boundary compression ratio value, for example, 0.2, and the maximum accessible capacity benchmark value of the distribution network under static scenarios, for example, 5 MW, to verify whether the dynamically corrected maximum accessible capacity value is, for example, 4 MW. Quarterly on-site stress testing: gradually increasing the output of distributed power sources, recording the deviation between the actual limit-crossing points and the dynamically corrected maximum accessible capacity value, requiring the deviation to be less than, for example, 10%.

[0132] Application scenario implementation example: When the assessment result shows a "critical" state, the preventive control strategy is automatically activated. If the "overload" state is displayed, a load reduction operation command is executed, with a command issuance delay of less than, for example, 200 milliseconds. Assessment result reports are generated daily, including the number of times each feeder exceeds limits and the maximum exceedance percentage.

[0133] Data security mechanisms include: two-factor authentication for database access, and encryption of data transmission using a specific bit depth, such as a 256-bit encryption algorithm. Modification operations are logged. Disaster recovery mechanisms include off-site backups configured with backup intervals set to, for example, one hour.

[0134] Example 2: Figure 2A schematic diagram of a distribution network carrying capacity quantitative assessment system according to the present invention is provided. The distribution network carrying capacity quantitative assessment system includes:

[0135] The parameter acquisition module is used to acquire distribution network topology parameters and the location of distributed power source access;

[0136] The over-limit identification module is used to monitor the tap position operation status of on-load tap-changing transformers in real time based on distribution network topology parameters and distributed power source access location, and to identify local voltage over-limit events caused by the increase in output of distributed power sources.

[0137] The reverse adjustment range module is used to determine the range of voltage reverse adjustment effect by coordinating the integral value of the impact vibration envelope of the tap changer operation with the eddy intensity distribution of the insulating oil flow field when a local voltage over-limit event triggers a down-shift operation.

[0138] The phase detection module is used to detect the phase offset angle of the grounding current injected by the distributed power source within the range of voltage reverse regulation effect, and to determine whether the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer.

[0139] The boundary compression module is used to couple the dynamic process of tap position switching with the phase offset constraint when the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer, and to quantify the voltage safety boundary compression ratio.

[0140] The capacity assessment module is used to correct the maximum accessible capacity according to the voltage safety boundary compression ratio and output the load capacity assessment result.

[0141] Example 3: The present invention provides a terminal device, which includes a processor, a memory, and a program or instructions stored in the memory and executable on the processor. When the program or instructions are executed by the processor, a method for quantitatively evaluating the carrying capacity of a power distribution network is implemented.

[0142] All calculations involved in the embodiments are dimensionless numerical calculations, and the preset parameters and thresholds in the calculations are set by those skilled in the art according to the actual situation.

[0143] It should be noted that this invention can be deployed on the device itself to realize embedded applications, or it can run on a PC or other terminal with a user interface, thereby meeting various hardware environments and usage requirements.

[0144] The above embodiments can be implemented, in whole or in part, by software, hardware, firmware, or any other combination thereof. When implemented using software, the above embodiments can be implemented, in whole or in part, as a computer program product. The computer program product includes one or more computer instructions or computer programs. When the computer instructions or computer programs are loaded or executed on a computer, all or part of the processes or functions described in the embodiments of this application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another. For example, the computer instructions can be transmitted from one website, computer, server, or data center to another website, computer, server, or data center via wireless or wired transmission; wired transmission methods include optical fiber, twisted pair, coaxial cable, etc.; wireless transmission includes infrared, microwave, etc. The computer-readable storage medium can be any available medium that a computer can access or a data storage device such as a server or data center containing one or more sets of available media. The available medium can be a magnetic medium (e.g., floppy disk, hard disk, magnetic tape), an optical medium (e.g., DVD), or a semiconductor medium. A semiconductor medium can be a solid-state drive.

[0145] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and modules described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0146] In the several embodiments provided in this application, it should be understood that the disclosed systems, apparatuses, and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0147] The modules described as separate components may or may not be physically separate. The components shown as modules may or may not be physical modules; they may be located in one place or distributed across multiple network modules. Some or all of the modules can be selected to achieve the purpose of this embodiment according to actual needs.

[0148] In addition, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module.

[0149] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0150] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

[0151] In conclusion, the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for quantitatively assessing the carrying capacity of a power distribution network, characterized in that, include: S1. Obtain the distribution network topology parameters and the location of distributed power source access; S2. Based on the distribution network topology parameters and the location of distributed power source access, monitor the operation status of the on-load tap-changing transformer in real time to identify local voltage over-limit events caused by the increase in output of distributed power sources. S3. When a local voltage over-limit event triggers a down-tapping operation, the integral value of the shock vibration envelope of the coordinated tap changer operation and the eddy current intensity distribution of the insulating oil flow field determine the range of the voltage reverse regulation effect, including: When a local voltage over-limit event caused by a rise in the output of a distributed power source triggers a down-segment operation, the operation impact vibration waveform is collected at the moment the tap changer down-segmentes. Envelope analysis is performed on the operational impact vibration waveform to extract the characteristic frequency band vibration energy envelope. The integral value of the characteristic frequency band vibration energy envelope during the downshift operation duration is used as the integral value of the tap changer operation impact vibration envelope. Simultaneously acquire image sequences of insulating oil flow field in the tap changer tank area; The fluid velocity vector field was calculated based on the insulating oil flow field image sequence, and the maximum vortex intensity value and its spatial distribution were extracted. Based on the mechanical impact energy propagation characteristics characterized by the integral value of the impact vibration envelope of the tap changer operation, and combined with the electromagnetic wave propagation medium state characterized by the maximum vortex intensity value of the insulating oil flow field, the range of voltage reverse regulation effect is calculated through the physical coupling effect of mechanical energy and fluid dynamic pressure. S4. Within the range of voltage reverse regulation effect, detect the phase offset angle of the grounding current injected by the distributed power source and determine whether the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer. S5. When the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer, the dynamic process of coupling tap switching and phase offset constraints, and the quantified voltage safety boundary compression ratio, including: The duration of the tap changer's gear switching action is obtained as a representation of the dynamic process of gear switching. The excess value of the phase offset angle exceeding the safety threshold of the insulation dielectric loss angle of the tap changer is extracted as the quantitative parameter of the phase offset constraint condition; Establish a physical correlation between the tap changer's tap position switching action duration and the excess value of the phase offset angle exceeding the safety threshold of the tap changer's insulation dielectric loss angle; The weighting coefficient for the impact of tap changer position switching action duration on voltage safety boundary is determined based on physical correlation. The influence weighting coefficients are applied to the static voltage safety boundary reference value to generate the voltage safety boundary compression ratio. S6. Correct the maximum accessible capacity according to the voltage safety boundary compression ratio, and output the load-bearing capacity assessment result.

2. The method for quantitatively assessing the carrying capacity of a power distribution network according to claim 1, characterized in that, Obtain distribution network topology parameters and distributed generation access locations, including: The connection relationships and electrical parameters of the lines in the distribution network are obtained as the distribution network topology parameters. The distribution network topology parameters include line resistance, line reactance, and line-to-ground capacitance. The specific node location of the distributed power source connected to the distribution network is obtained as the connection location of the distributed power source. The connection location of the distributed power source corresponds one-to-one with the node identifier in the distribution network topology parameters. Establish a mapping relationship between distribution network topology parameters and the location of distributed power source access to form a basic dataset for dynamic analysis of the distribution network.

3. The method for quantitatively assessing the carrying capacity of a power distribution network according to claim 1, characterized in that, Based on real-time monitoring of the on-load tap-changing transformer's tap position status according to distribution network topology parameters and distributed generation connection locations, local voltage over-limit events caused by distributed generation output increases are identified, including: Locate the node where the on-load tap-changing transformer is located and the node where the distributed power source is connected in the distribution network topology parameters; Real-time acquisition of voltage values ​​at nodes where on-load tap-changing transformers are located and current output values ​​at nodes where distributed power sources are connected; When the current output value of the node where the distributed power source is connected exceeds the historical benchmark output value and the duration reaches a preset threshold, it is determined that a distributed power source output increase has occurred. The system synchronously monitors the changes in the tap position of the on-load tap-changing transformer. If the tap position is downshifting and the voltage value of the node where the transformer is located exceeds the upper voltage threshold, it is determined that a local voltage over-limit event has occurred due to the increase in the output of the distributed power source.

4. The method for quantitatively assessing the carrying capacity of a power distribution network according to claim 1, characterized in that, Within the range of voltage reverse regulation effect, the phase offset angle of the grounding current injected by the distributed power source is detected to determine whether the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer, including: Locate the connection points of all distributed power sources within the range of voltage reverse regulation effect; Real-time acquisition of the injected grounding current waveform and the reference waveform of the system neutral point voltage at each location of the distributed power supply access point; The phase difference angle between the ground current waveform and the reference waveform of the system neutral point voltage is calculated as the phase offset angle of the ground current. The standard dielectric loss tangent value of the tap changer insulation material is used as the safety threshold for the dielectric loss angle of the tap changer insulation. The phase offset angle of the grounding current is numerically compared with the safety threshold of the insulation dielectric loss angle of the tap changer. If the phase offset angle is greater than the safety threshold for the dielectric loss angle of the tap changer insulation, it is determined to exceed the safety threshold.

5. The method for quantitatively assessing the carrying capacity of a power distribution network according to claim 1, characterized in that, The physical correlation between the tap changer position switching action duration and the phase offset angle exceeding the specified value is established through the following method: Based on the correspondence records between gear shifting action duration and phase offset angle exceeding value in the historical fault database, a linear proportional mapping rule is established between the increase in action duration and the increase in phase offset exceeding value.

6. The method for quantitatively assessing the carrying capacity of a power distribution network according to claim 1, characterized in that, The maximum connectable capacity is adjusted based on the voltage safety boundary compression ratio, and the output load capacity assessment results are included: Obtain the baseline value of the maximum accessible capacity of the distribution network under static scenarios; Extract the capacity correction factor characterized by the voltage safety boundary compression ratio; The capacity correction factor is applied to the baseline value of the maximum accessible capacity of the distribution network under static scenarios to generate the dynamically corrected maximum accessible capacity value. The carrying capacity assessment result is generated by comparing the maximum accessible capacity value after dynamic correction with the actual output value of distributed power sources.

7. A system for quantitatively assessing the carrying capacity of a distribution network, used to implement the method for quantitatively assessing the carrying capacity of a distribution network as described in any one of claims 1-6, characterized in that, include: The parameter acquisition module is used to acquire distribution network topology parameters and the location of distributed power source access; The over-limit identification module is used to monitor the tap position operation status of on-load tap-changing transformers in real time based on distribution network topology parameters and distributed power source access location, and to identify local voltage over-limit events caused by the increase in output of distributed power sources. The reverse adjustment range module is used to determine the range of voltage reverse adjustment effect by coordinating the integral value of the impact vibration envelope of the tap changer operation with the eddy intensity distribution of the insulating oil flow field when a local voltage over-limit event triggers a down-shift operation. The phase detection module is used to detect the phase offset angle of the grounding current injected by the distributed power source within the range of voltage reverse regulation effect, and to determine whether the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer. The boundary compression module is used to couple the dynamic process of tap position switching with the phase offset constraint when the phase offset angle exceeds the safety threshold of the insulation dielectric loss angle of the tap changer, and to quantify the voltage safety boundary compression ratio. The capacity assessment module is used to correct the maximum accessible capacity according to the voltage safety boundary compression ratio and output the load capacity assessment result.

8. A terminal device, characterized in that, The terminal device includes: a processor, a memory, and a program or instructions stored in the memory and executable on the processor. When the program or instructions are executed by the processor, they implement the quantitative assessment method for the carrying capacity of a power distribution network as described in any one of claims 1-6.

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