A method and system for identifying line parameters of an ultra-high voltage transmission ring network

Abstract

The present invention discloses a method and system for identifying line parameters of an ultra-high voltage power transmission loop network. The method includes: obtaining effective measurement data corresponding to a preset scenario based on the preset scenario; obtaining voltage drop phasors of each line in the power transmission loop network based on the scenario and the effective measurement data; and determining an identification result of the ultra-high voltage power transmission loop network line in the scenario based on the voltage drop phasors of each line. The present invention improves the overall quality of the basic model data of power grid operation and simultaneously improves the accuracy of calculation based on line measurement data.

Description

Technical Field

[0001] The present invention relates to the field of power system calculations, and particularly to a method and system for identifying line parameters of an extra-high voltage transmission loop network. Background Art

[0002] With the completion of the AC-DC hybrid power grid, the power grid shows a phenomenon of huge scale, complex network operation characteristics, and great difficulty in power grid regulation and control. Online applications play a more fundamental and crucial role. As the model basis of online applications, the accuracy of line parameters directly affects the credibility of network analysis and auxiliary decision-making. At present, the line parameters of the dispatching automation system adopt fixed values (measured values or nameplate parameter values) without correction throughout the year for online application use.

[0003] Currently, the dispatching system automation department uses online parameters, and the method department and protection department use offline parameters given in the measured reports. However, with the changes in external conditions such as the equipment operation environment, current-carrying capacity, season, time period, and system load operation level, the operation parameters of power grid equipment change, and the actual system power grid parameters are not re-measured. Even if the power grid parameters deviate, offline parameters are still used. For the protection department, since the fault location calculation is based on the basic power grid parameters, this increases the risk of large errors in fault location. Summary of the Invention

[0004] In order to solve the above-mentioned deficiencies in the prior art, the present invention provides a method and system for identifying line parameters of an extra-high voltage transmission loop network. The present invention utilizes the massive SCADA measurements of lines in the extra-high voltage transmission loop network under different scenarios, and through the parameter combinations of the transmission loop network line parameters within the deviation range, with the minimum average voltage drop of the loop network loop as the target, adopts a statistical analysis method to identify the loop network line parameters and achieve accurate estimation of the line parameters.

[0005] A method for identifying line parameters of an extra-high voltage transmission loop network provided by the present invention includes:

[0006] Obtaining the effective measurement data corresponding to the scenario based on a pre-set scenario;

[0007] Obtaining the voltage drop phasors of each line in the transmission loop network based on the scenario and the effective measurement data;

[0008] Determining the identification result of the extra-high voltage transmission loop network lines in the scenario based on the voltage drop phasors of each line.

[0009] Preferably, the obtaining the voltage drop phasors of each line in the transmission loop network based on the scenario and the effective measurement data includes:

[0010] Determining the lines with fixed parameters in the transmission loop network corresponding to the scenario;

[0011] Based on the line with fixed parameters in the transmission ring network, search for parameters corresponding to the remaining lines;

[0012] The voltage drop phase of each line in the scenario is obtained by calculation based on the effective measurement data and the parameters of all lines.

[0013] Preferably, the determining of the line with fixed parameters in the power transmission ring network corresponding to the scenario includes:

[0014] Based on the wide area measurement system, in the scenario, the lines with dual-terminal PMU measurement are selected from the ultra-high voltage transmission ring network;

[0015] Select effective two-terminal PMU measurement based on voltage phase angle difference;

[0016] Based on the effective PMU measurement data, the least square method is used to identify the line parameters to obtain the identification parameters;

[0017] Based on the PMU measurement data and identification parameters on one side of the line, estimate the PMU measurement on the other side of the line;

[0018] Constitute a comparative evaluation index based on the PMU quantity measurement on the other side of the line and the corresponding PMU measurement data;

[0019] The evaluation indicators of all lines with dual-end PMU measurement are ranked, and the line with the smallest evaluation indicator is selected as the line with fixed parameters in the transmission ring network under the scenario, and the identification parameters corresponding to the line are used as the fixed parameters of the transmission ring network under the scenario.

[0020] Preferably, the step of searching for parameters corresponding to other lines based on the line with fixed parameters in the power transmission ring network includes:

[0021] Based on the lines with fixed transmission ring network parameters in the scenario, determining the transmission ring network line parameter set by enumeration method according to the set search space;

[0022] Generate parameters corresponding to other lines in the transmission ring network based on the line parameter set;

[0023] The line parameters include resistance, reactance and ground susceptance.

[0024] Preferably, the acquisition of the effective measurement data includes:

[0025] Selecting measurement data collected from the ultra-high voltage transmission ring network in the scenario;

[0026] The box plot method is used to detect the measurement data in the scenario and eliminate bad measurement data;

[0027] The measured data includes active power, reactive power and voltage.

[0028] Preferably, the measured data collected from the extra-high voltage transmission loop network selected under the scenario includes:

[0029] Construct a scenario measurement data set for the scenario;

[0030] When the scenario is the operation mode, select the measured data of the transmission loop network based on the set operation mode and save it to the corresponding scenario measurement data set;

[0031] When the scenario is the season, select the measured data of the transmission loop network line based on the average temperature of the four seasons and save it to the corresponding scenario measurement data set;

[0032] When the scenario is the operation load rate of the power grid, select the measured data of the transmission loop network line based on the set operation load rate and save it to the corresponding scenario measurement data set;

[0033] The operation modes include peak load, off-peak load, and shoulder load.

[0034] Preferably, calculating the voltage drop phasor of each line under the scenario based on the effective measured data and the parameters of all lines includes:

[0035] Obtain the line end current corresponding to the scenario based on the measured data of active power, reactive power, and voltage under the scenario;

[0036] Obtain the line impedance line current based on the line end current and parameters corresponding to the scenario;

[0037] Obtain the voltage drop phasor between the two ends of the line based on the line impedance line current and the measured data of voltage.

[0038] Preferably, the voltage drop phasor is calculated according to the following formula:

[0039]

[0040] In the formula: is the voltage drop phasor of line ij; P ji is the active power at the j end of line ij; R is the line resistance; Q ji is the reactive power at the j end of line ij; U j is the bus voltage at the j end; y c is the line-to-ground susceptance; X is the line reactance.

[0041] Preferably, determining the identification result of the extra-high voltage transmission loop network line in the scenario based on the voltage drop phasor of each line includes:

[0042] Under the described scenario, based on the voltage drop phasors of all lines, calculate the sum of the loop voltage drops of the transmission ring network according to the electrical constraint that the sum of the ring network voltage phasor drops is zero;

[0043] Sort according to the average loop voltage drop, and use statistical analysis methods to calculate the maximum value, minimum value and variance of the grouping parameters;

[0044] Select the parameter with the smallest variance as the final identification result of the extra-high voltage transmission ring network line.

[0045] Preferably, the electrical constraint is shown as the following formula:

[0046]

[0047] In the formula: dU i-1,i is the voltage drop phasor of the ring network line (i - 1, i); N is the number of ring network nodes.

[0048] Preferably, the scenario is set according to the power grid operation mode, season and power grid operation load rate.

[0049] Based on the same inventive concept, the present invention also provides a line parameter identification system for an extra-high voltage transmission ring network, including:

[0050] An acquisition module, configured to acquire the effective measurement data corresponding to the scenario based on a preset scenario;

[0051] A calculation module, configured to obtain the voltage drop phasors of each line in the transmission ring network based on the scenario and the effective measurement data;

[0052] A result module, configured to determine the identification result of the extra-high voltage transmission ring network line in the scenario based on the voltage drop phasors of each line.

[0053] Preferably, the calculation module includes:

[0054] A determination sub-module, configured to determine the lines with fixed parameters in the transmission ring network corresponding to the scenario;

[0055] An acquisition sub-module, configured to search for the parameters corresponding to the remaining lines based on the lines with fixed parameters in the transmission ring network;

[0056] A calculation sub-module, configured to perform calculations based on the effective measurement data and the parameters of all lines to obtain the voltage drop phasors of each line in the scenario.

[0057] Preferably, the determination sub-module includes:

[0058] A screening unit, configured to screen out the lines with dual-terminal PMU measurements from the extra-high voltage transmission ring network based on the wide-area measurement system under the scenario;

[0059] A selection unit, configured to select effective double - end PMU measurements according to the voltage phase angle difference;

[0060] An identification parameter acquisition unit, configured to identify line parameters by using the least - squares method based on the effective PMU measurement data, and obtain the identification parameters;

[0061] An estimation unit, configured to estimate the PMU measurement value on the other side of the line based on the PMU measurement data on one side of the line and the identification parameters;

[0062] A composition unit, configured to form a comparative evaluation index based on the PMU measurement value on the other side of the line and the corresponding PMU measurement data;

[0063] A determination unit, configured to sort the evaluation indexes of all lines with double - end PMU measurements, select the line with the smallest evaluation index as the line with fixed parameters in the transmission ring network under the scenario, and use the identification parameters corresponding to the line as the fixed parameters of the transmission ring network under the scenario.

[0064] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0065] The technical solution provided by the present invention obtains the corresponding effective measurement data based on a preset scenario; obtains the voltage drop phasors of each line in the transmission ring network based on the scenario and the effective measurement data; determines the identification results of the extra - high - voltage transmission ring network lines under the scenario. By the method provided by the present invention, it helps dispatch and operation and maintenance personnel to improve the overall quality of the operation basic model data in the power grid, and improves the accuracy of calculations based on line measurement data by updating the data.

[0066] The technical solution provided by the present invention uses a large amount of multi - source historical data such as SCADA measurements and PMU measurements stored in the dispatching automation system to identify the steady - state parameters of lines under different operating conditions, different external environments, and different load rates, so as to provide more reliable and more reference - significant equipment parameters for power grid operation analysis. Brief Description of the Drawings

[0067] Figure 1 It is a flowchart of a method for identifying line parameters of an extra - high - voltage transmission ring network in the present invention;

[0068] Figure 2 It is a specific flowchart of a method for identifying line parameters of a 500kV transmission ring network in an embodiment of the present invention;

[0069] Figure 3 It is a schematic diagram of using the box - plot method to detect outliers in the present invention;

[0070] Figure 4It is a schematic diagram of the structure of the power transmission ring network of the present invention;

[0071] Figure 5 It is a schematic diagram of the transmission line parameter identification model of the present invention. DETAILED DESCRIPTION

[0072] In order to better understand the present invention, the content of the present invention is further described below in conjunction with the accompanying drawings and examples.

[0073] Example 1

[0074] like Figure 1 As shown, the present invention provides a line parameter identification method for an ultra-high voltage transmission ring network, comprising:

[0075] S1. Acquire effective measurement data corresponding to a preset scenario based on the preset scenario;

[0076] S2. Obtaining the voltage drop phase of each line in the transmission ring network based on the scenario and effective measurement data;

[0077] S3. Based on the voltage drop phase of each line, determine the identification result of the ultra-high voltage transmission ring network line in the scenario.

[0078] In this embodiment, the present invention is introduced by taking a 500kv network as an example. Figure 2 A line parameter identification method of a 500kV transmission ring network in this embodiment is specifically explained as follows, including:

[0079] Firstly, the active power, reactive power and voltage measurement data collected from the 500kV transmission ring network were selected according to different scenarios such as grid operation mode, season and load rate, and the box plot method was used to eliminate the bad measurement data;

[0080] Secondly, the lines of fixed parameters of the transmission ring network are determined based on PMU data;

[0081] Then, based on the effective measurement data and search parameters, the voltage drop phase quantity of a single line of the transmission ring network line is calculated;

[0082] Finally, the average voltage drop of the transmission ring network loop is calculated, and the final identification result of the 500kV transmission ring network line is obtained by using statistical analysis method.

[0083] (1) SCADA measurement data extraction and preprocessing of transmission ring network lines

[0084] According to different scenarios such as power grid operation mode, season, load rate, etc., the measured data of active power P, reactive power Q and bus voltage U of the transmission ring network line are selected, and the following methods are used: Figure 3 The box plot shown detects outliers. They are as follows:

[0085] 1) Classify the measurement data of the transmission ring network according to peak load, valley load, and shoulder load, and establish a measurement data set corresponding to different operation mode scenarios;

[0086] 2) Select the measurement data of the transmission ring network lines according to the average ambient temperature in different seasons of spring, summer, autumn, and winter, and establish a measurement data set for external meteorological scenarios;

[0087] 3) Select the measurement data of the transmission ring network lines according to the grid operation load rate, and establish a measurement data set for line operation scenarios;

[0088] 4) Use the box plot method to detect the bad measurement data of active power, reactive power, and bus voltage in different application scenarios, and eliminate the bad measurement data in different operation scenarios.

[0089] (2) Calculation and selection of fixed parameters of transmission ring network lines

[0090] 1) Based on the wide area measurement system, screen out the lines with phasor measurement unit (PMU) measurements from the 500 kV transmission ring network;

[0091] 2) Judge whether the double-ended PMU measurement is valid according to the voltage phase angle difference;

[0092] 3) Based on the valid PMU data, use the least squares method to identify the line parameters and obtain the identified parameters;

[0093] 4) Based on the PMU measurement data on one side of the line and the identified parameters, estimate the PMU measurement on the other side, and form a comparative evaluation index with the PMU measurement value.

[0094] 5) Sort the evaluation indexes, and select the line identification parameters corresponding to the minimum index as the fixed parameters of the transmission ring network.

[0095] (3) Calculation of single-line voltage drop phasor of transmission ring network lines

[0096] 1) Select the valid measurement data of active power P, reactive power Q, and bus voltage U of the preprocessed lines in different scenarios given in step 1;

[0097] 2) Based on the lines with fixed parameters of the transmission ring network in different scenarios given in step 2, search and combine the remaining line parameters of the transmission ring network. The line parameters include resistance, reactance, and shunt capacitance to ground. The search space is limited to the range of plus or minus 20% of the original parameter value, and the search step is 0.01. Determine the set of line parameter groups corresponding to the remaining lines through the enumeration method, and form the parameters of each line of the transmission ring network based on the set of line parameter groups.

[0098] 3) Calculate the voltage drop phasor of each line on the transmission ring network according to the above valid measurement data and parameters Voltage drop phasor is calculated as follows:

[0099] As Figure 5 shown, the voltage phasor difference between the two ends of the line is:

[0100]

[0101] In Equation (1.1), is the voltage drop phasor of line ij; is the bus voltage phasor at end i; is the bus voltage phasor at end j; R is the line resistance; X is the line reactance; is the current on the i side of the line impedance; is the current on the j side of the line impedance.

[0102] The current at the end of the line is

[0103]

[0104] In Equation (1.2), P ij is the active power at end j of line ij; Q ji is the reactive power at end j of line ij; is the conjugate phasor of phasor ; is the conjugate phasor of the bus voltage phasor at end j.

[0105] The current on the j side of the line impedance is:

[0106]

[0107] In Equation (1.3), y c is the shunt admittance to ground of the line.

[0108] Substitute Equation (1.2) into Equation (1.3):

[0109]

[0110] Substitute Equation (1.4) into Equation (1.1) to obtain:

[0111]

[0112] Taking the voltage phasor at end j as the reference phasor, the above equation becomes:

[0113]

[0114] where P jiThe active power at the j - end of line ij, with the direction from j to i being positive and from i to j being negative; R is the line resistance; Q ji is the reactive power at the j - end of line ij; U j is the magnitude of the bus voltage at the j - end; y c is the line - to - ground susceptance; X is the line reactance.

[0115] (4) Identification of 500kV transmission loop network line parameters

[0116] As shown in the appendix Figure 4 , along all lines of the 500kV ring - shaped transmission network, there is an electrical constraint that the sum of voltage - drop phasors is 0, as shown in Equation (1.7), where N is the number of nodes in the ring network.

[0117]

[0118] Based on the single - line line voltage - drop phasor results given in Step 3, according to different scenarios such as the selected operation mode, season, load factor, etc., calculate the sum of loop voltage drops of the 500kV transmission loop network according to Equation (1.7), sort according to the average loop voltage drop, and use statistical analysis methods to calculate the maximum value, minimum value, and variance of the grouped parameters, and select the one with the smallest variance as the final identification result of the 500kV transmission loop network lines.

[0119] Embodiment 2

[0120] Based on the same inventive concept, the present invention also provides a line parameter identification system for an extra - high - voltage transmission loop network, including:

[0121] An acquisition module for acquiring the effective measurement data corresponding to the scenario based on a preset scenario;

[0122] A calculation module for obtaining the voltage - drop phasors of each line in the transmission loop network based on the scenario and the effective measurement data;

[0123] A result module for determining the identification result of the extra - high - voltage transmission loop network lines in the scenario based on the voltage - drop phasors of each line.

[0124] In the embodiment, the calculation module includes:

[0125] A determination sub - module for determining the lines with fixed parameters in the transmission loop network corresponding to the scenario;

[0126] An acquisition sub - module for searching for the parameters corresponding to the remaining lines based on the lines with fixed parameters in the transmission loop network;

[0127] A calculation sub - module for calculating based on the effective measurement data and the parameters of all lines to obtain the voltage - drop phasors of each line in the scenario.

[0128] In an embodiment, the determination sub-module includes:

[0129] A screening unit, configured to screen out lines with double-ended PMU measurements from an extra-high voltage transmission loop network in the scenario based on a wide-area measurement system;

[0130] A selection unit, configured to select effective double-ended PMU measurements according to the voltage phase angle difference;

[0131] An identification parameter acquisition unit, configured to identify line parameters by using the least squares method based on effective PMU measurement data to obtain identification parameters;

[0132] An estimation unit, configured to estimate the PMU measurement value on the other side of the line based on the PMU measurement data on one side of the line and the identification parameters;

[0133] A composition unit, configured to compose a comparative evaluation index based on the PMU measurement value on the other side of the line and the corresponding PMU measurement data;

[0134] A determination unit, configured to sort the evaluation indexes of all lines with double-ended PMU measurements, select the line with the smallest evaluation index as the line with fixed parameters in the transmission loop network in the scenario, and use the identification parameters corresponding to the line as the fixed parameters of the transmission loop network in the scenario.

[0135] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0136] The present application is described with reference to the flowcharts and / or block diagrams of methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or block in the flowcharts and / or block diagrams, and the combination of processes and / or blocks in the flowcharts and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate means for implementing the functions specified in one Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0137] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to operate in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction device that implements the functions specified in one or more of the processes and / or blocks Figure 1 one or more of the processes and / or blocks Figure 1 specified in the function.

[0138] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, whereby the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one or more of the processes and / or blocks Figure 1 one or more of the processes and / or blocks Figure 1 specified in the function.

[0139] The above are only embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention are included in the scope of the claims of the present invention pending approval of the application.

Claims

1. A method for identifying line parameters of an ultra-high voltage transmission ring network, characterized in that, include: Acquire effective measurement data corresponding to a preset scenario based on the preset scenario; Based on the scenario and effective measurement data, obtain the voltage drop phase of each line in the transmission ring network; Determine the identification result of the ultra-high voltage transmission ring network line in the scenario based on the voltage drop phase of each line; The step of determining the identification result of the ultra-high voltage transmission ring network line in the scenario based on the voltage drop phase of each line includes: In the scenario, based on the voltage drop phases of all lines, the sum of the voltage drops of the transmission ring network loop is calculated according to the electrical constraint that the sum of the voltage drop phases of the ring network is zero; Sort by the average loop voltage drop, and use statistical analysis methods to calculate the maximum, minimum and variance of grouping parameters; The parameter with the smallest variance is selected as the final identification result of the ultra-high voltage transmission ring network line.

2. The method according to claim 1, wherein The step of obtaining the voltage drop phase quantity of each line in the power transmission ring network based on the scenario and the effective measurement data includes: Determine a line with fixed parameters in a power transmission ring network corresponding to the scenario; Based on the line with fixed parameters in the transmission ring network, search for parameters corresponding to the remaining lines; The voltage drop phase of each line in the scenario is obtained by calculation based on the effective measurement data and the parameters of all lines.

3. The method according to claim 2, characterized in that, The determining of a line with fixed parameters in the power transmission ring network corresponding to the scenario includes: Based on the wide area measurement system, in the scenario, the lines with dual-terminal PMU measurement are selected from the ultra-high voltage transmission ring network; Select effective two-terminal PMU measurement based on voltage phase angle difference; Based on the effective PMU measurement data, the least square method is used to identify the line parameters to obtain the identification parameters; Based on the PMU measurement data and identification parameters on one side of the line, estimate the PMU measurement on the other side of the line; Constitute a comparative evaluation index based on the PMU quantity measurement on the other side of the line and the corresponding PMU measurement data; The evaluation indicators of all lines with dual-end PMU measurement are ranked, and the line with the smallest evaluation indicator is selected as the line with fixed parameters in the transmission ring network under the scenario, and the identification parameters corresponding to the line are used as the fixed parameters of the transmission ring network under the scenario.

4. The method according to claim 2, characterized in that The searching for parameters corresponding to other lines based on the line with fixed parameters in the power transmission ring network includes: Based on the lines with fixed transmission ring network parameters in the scenario, determining the transmission ring network line parameter set by enumeration method according to the set search space; Generate parameters corresponding to other lines in the transmission ring network based on the line parameter set; The line parameters include resistance, reactance and ground susceptance.

5. The method according to claim 1, characterized in that The acquisition of the effective measurement data includes: Selecting measurement data collected from the ultra-high voltage transmission ring network in the scenario; The box plot method is used to detect the measurement data in the scenario and eliminate bad measurement data; The measured data includes active power, reactive power and voltage.

6. The method according to claim 5, characterized in that The measurement data collected by the ultra-high voltage transmission ring network under the scenario is selected, including: Constructing a scene measurement dataset for the scene; When the scenario is an operation mode, the measurement data of the power transmission ring network is selected based on the set operation mode, and saved to the corresponding scenario measurement data set; When the scenario is season, select the measurement data of the transmission ring network line based on the average temperature of the four seasons, and save it to the corresponding scenario measurement data set; When the scenario is the operating load rate of the power grid, select the measurement data of the transmission ring network line based on the set operating load rate, and save it to the corresponding scenario measurement data set; The operating modes include peak load, valley load, and shoulder load.

7. The method according to claim 2, wherein The calculation based on the effective measurement data and the parameters of all lines to obtain the voltage drop phasors of each line under the scenario includes: Obtain the line end current corresponding to the scenario based on the measurement data of active power, reactive power, and voltage under the scenario; Obtain the line impedance line current based on the line end current corresponding to the scenario and the parameters; Obtain the voltage drop phasors between the two ends of the line based on the line impedance line current and the measurement data of voltage.

8. The method according to claim 7, wherein The voltage drop phasor is calculated according to the following formula: Wherein: is the voltage drop phasor of line ij; P ji is the active power at the j end of line ij; R is the line resistance; Q ji is the reactive power at the j end of line ij; U j is the bus voltage at the j end; y c is the line shunt susceptance; X is the line reactance.

9. The method according to claim 1, wherein The electrical constraint is shown in the following formula: where: dU i-1,i is the voltage drop phasor of the loop network line (i - 1, i); N is the number of loop network nodes.

10. The method according to claim 1, characterized in that The scenario is set according to the power grid operation mode, season, and power grid operation load rate.

11. A line parameter identification system for an ultra-high voltage transmission ring network, characterized in that, It includes: An acquisition module for obtaining the effective measurement data corresponding to the scenario based on the preset scenario; A calculation module for obtaining the voltage drop phasors of each line in the transmission ring network based on the scenario and the effective measurement data; A result module for determining the identification result of the extra-high voltage transmission ring network line in the scenario based on the voltage drop phasors of each line; The result module includes: Based on the voltage drop phasors of all lines in the scenario, calculate the sum of the loop voltage drops of the transmission ring network according to the electrical constraint that the sum of the loop voltage drop phasors is zero; Sort according to the average loop voltage drop, and use statistical analysis methods to calculate the maximum value, minimum value, and variance of the grouping parameters; Select the parameter with the smallest variance as the final identification result of the extra-high voltage transmission ring network line.

12. The system according to claim 11, wherein The calculation module includes: A determination sub-module for determining the lines with fixed parameters in the transmission ring network corresponding to the scenario; An acquisition sub-module for searching for the parameters corresponding to the other lines based on the lines with fixed parameters in the transmission ring network; A calculation sub-module for calculating based on the effective measurement data and the parameters of all lines to obtain the voltage drop phasors of each line under the scenario.

13. The system according to claim 12, wherein The determination sub-module includes: A screening unit for screening out the lines with double-ended PMU measurements from the extra-high voltage transmission ring network under the scenario based on the wide area measurement system; A selection unit for selecting effective double-ended PMU measurements according to the voltage phase angle difference; An identification parameter acquisition unit for identifying the line parameters by the least squares method based on the effective PMU measurement data to obtain the identification parameters; An estimation unit for estimating the PMU measurement on the other side of the line based on the PMU measurement data on one side of the line and the identification parameters; A composition unit for composing a comparative evaluation index based on the PMU measurement on the other side of the line and the corresponding PMU measurement data; A determination unit for sorting the evaluation indexes of all lines with double-ended PMU measurements, selecting the line with the smallest evaluation index as the line with fixed parameters in the transmission ring network under the scenario, and taking the identification parameters corresponding to the line as the fixed parameters of the transmission ring network under the scenario.

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