On-line calibration method for measuring error of instrument current transformer in parallel line scene

Abstract

The present application relates to a kind of instrument current transformer measurement error online calibration method in parallel line scene, comprising: the equivalent impedance of line is dynamically adjusted based on the action compensation equipment deployed in parallel line, the symmetry of current of parallel line is realized to be destroyed;Current of two lines in parallel line is used to build the index indicating the current correlation characteristics between parallel lines, and the working state of the compensation device action indicator for indicating the action of the compensation device is constructed based on the index;Current symmetry destruction time of parallel line is determined based on compensation device action indicator, and current transformer measurement error solving equation is established based on the measurement data before and after symmetry destruction time, and the measurement error of current transformer is solved;The destruction of current symmetry is realized by introducing the action of the action compensation equipment in power system, and the online calibration problem caused by the linear correlation of current between parallel lines in actual power grid can be solved.

Description

Technical Field

[0001] This invention relates to the field of power transmission equipment condition assessment and online monitoring, and in particular to an online calibration method for the measurement error of instrument current transformers in parallel line scenarios. Background Technology

[0002] Current transformers are widely used measuring devices in high-voltage power systems. Their main function is to reduce large currents in the high-voltage grid to small current signals by a given coefficient. Measurement error (ME) is a key performance indicator of current transformers. However, because current transformers are sensitive to factors such as ambient temperature, external electric fields, and leakage current, ME increases during long-term operation and may exceed the allowable error limit. The ME of a current transformer significantly affects the overall accuracy of the measurement chain, leading to inaccuracies or failures in downstream applications such as relay protection, control, and metering. Therefore, ensuring the measurement performance of current transformers during long-term operation is crucial.

[0003] Traditional power outage detection methods suffer from inherent drawbacks such as low verification efficiency, high cost, and inability to acquire errors in real time. In recent years, online calibration methods have received widespread attention, with the mainstream approach being analytical modeling based on a single-line network model of the power system. The paper "Line impedance estimation based on synchrophasor measurements for power distribution systems" proposes using instrument transformers (MEs) and transmission line parameters as unknowns. It constructs equations relating the measured values ​​and unknowns using transmission line voltage drop constraints and node current balance constraints, and then solves for the MEs using the least squares method. This analytical modeling method constructs a system of equations by combining measurements from multiple time periods; the full rank of this system of equations is the foundation for online ME calibration.

[0004] However, in actual power transmission networks, parallel lines, represented by two-circuit overhead transmission lines on the same tower, are widely used, accounting for over 95% of high-voltage transmission networks. The parallel construction method, with shared busbars at both ends and passing through the same transmission corridor, results in a linear correlation of currents between the parallel lines. Consequently, the current transformer (ME) estimation equations constructed do not meet the required rank, making them unsolvable by the aforementioned methods. Existing online calibration methods for current transformers (ME) have all failed.

[0005] Therefore, it is necessary to propose an online calibration method for the measurement error of instrument current transformers in parallel circuit scenarios. Summary of the Invention

[0006] This invention addresses the technical problems existing in the prior art by providing an online calibration method for the measurement error of instrument current transformers in parallel circuit scenarios. This method solves the problems of existing online calibration methods failing and traditional power outage verification methods being labor-intensive, resource-intensive, and having poor real-time performance in parallel circuit scenarios.

[0007] According to a first aspect of the present invention, an online calibration method for the measurement error of an instrument current transformer in a parallel circuit scenario is provided, comprising:

[0008] Step 1: Based on the motion compensation equipment deployed on the parallel lines, the equivalent impedance of the lines is dynamically adjusted to change the shunt ratio of the parallel lines, thereby disrupting the current symmetry of the parallel lines.

[0009] Step 2: Construct an index characterizing the current correlation between two parallel lines based on the current of the two lines in the parallel line, and construct a compensation device action indicator based on the index to indicate the working status of the action compensation device.

[0010] Step 3: Determine the moment when the current symmetry of the parallel line is disrupted based on the operation indicator of the compensation device; establish the current transformer measurement error solution equation based on the measurement data before and after the symmetry disruption moment; solve for the measurement error of the current transformer; and perform online calibration of the current transformer based on the measurement error.

[0011] Based on the above technical solution, the present invention can also be improved as follows.

[0012] Optionally, step 2 includes:

[0013] Step 201: Extract indicators characterizing the current correlation between parallel lines. ;

[0014] In the formula, and For any i-th and j-th current transformers in parallel lines, respectively... The measured current value at a given time;

[0015] Step 202, extract the indicators The amplitude and phase are used as time-series characteristic parameters:

[0016] ;

[0017] ;

[0018] In the formula, For phasor magnitude, The phasor phase angle;

[0019] Step 203: Construct an autoencoder model. Construct a modeling dataset using the features of the time-series feature parameters. Train an autoencoder model based on the dataset to obtain the optimal parameters that satisfy the minimum loss function. Construct a residual threshold based on the reconstruction residuals of the autoencoder model during the training process.

[0020] Step 204: Input the real-time current data into the autoencoder model to obtain the reconstruction residual at the current time, and compare the reconstruction residual at the current time with the residual threshold to obtain the judgment value of the action recognition flag bit of the compensation device action indicator.

[0021] Optionally, the process of constructing the autoencoder model in step 203 includes:

[0022] Step 20301: Extract the temporal feature parameters of the current motion compensation device in its working state to form the dataset. ;

[0023] In the formula, , , Total number of time points in the dataset used for modeling;

[0024] Step 20302, construct the autoencoder model based on the dataset X as follows: ;

[0025] In the formula, This refers to the data at time t in dataset X;

[0026] During the coding process: This is the weight matrix. For bias vectors, For activation function, As latent variables;

[0027] During the decoding process: This is the weight matrix. For bias vectors, For activation function, To rebuild the output;

[0028] Step 20303: Construct the loss function and find the optimal parameter set that minimizes the loss function. ;

[0029] Step 20304, construct the residual threshold based on the reconstruction residual during the training process:

[0030] .

[0031] Optionally, step 204 includes:

[0032] Step 20401: Collect real-time current data for the parallel lines. ;

[0033] Step 20402: Extract the time-series feature parameters of the real-time current data feature quantities. The data is then fed into the trained autoencoder model to obtain the reconstructed residual at the current time step. ;

[0034] Step 20403: Reconstruct the residual at the current time. With the residual threshold Compare and determine the current motion compensation device identification flag. :

[0035] .

[0036] Optionally, step 204 may be followed by:

[0037] Step 205, when the motion compensation device The number of consecutive data points with a value of 1 reached At that time, dynamically update the flag bit. Set to 1;

[0038] Step 206, summarize the above. Current data is collected at any time to generate a new dataset. ;

[0039] Step 207: Re-model the autoencoder and determine the residual threshold limit; after the autoencoder model is updated, the flag bits will be dynamically updated. Set to 0.

[0040] Optionally, step 3 includes:

[0041] Step 301: Construct the current measurement matrix for the current transformers in the same phase group. :

[0042] ;

[0043] In the formula, n is the serial number of the current transformer. This indicates the number of current transformers, and T is the number of time points. This represents the current measurement value of the nth current transformer at time T, indicated by the superscript. It is the transpose symbol. This represents the current measurement value of the nth current transformer at each moment. Indicates all A matrix composed of the current measurement values ​​of each current transformer at various times;

[0044] Step 302, based on Kirchhoff's current law, construct the equation for solving the measurement error of the current transformer as follows:

[0045] ;

[0046] In the formula, , The lines are respectively The ratio error and phase error of the current transformer;

[0047] Step 303: Solve the measurement error equation using a solver to obtain the estimated measurement error values ​​for each current transformer.

[0048] Optionally, step 3 may be followed by:

[0049] Step 4: After the motion compensation device enters a stable operating condition, extract the historical measurement error data to form an error matrix, and use statistical methods to extract the dense region of error distribution in the error matrix to determine the measurement error of each current transformer.

[0050] Optionally, step 4 includes:

[0051] Step 401: Summarize all historical data of measurement error assessment results and construct an assessment error matrix. :

[0052] ;

[0053] In the formula, and They represent the first Current transformer The ratio error assessment value and phase offset assessment value of each step. Characterizes the total number of error assessments;

[0054] Step 402, evaluate the error matrix. Cluster analysis was performed to extract the cluster with the largest number of points, and the mean within the cluster was taken as the final online error calibration result.

[0055] According to a second aspect of the present invention, an online calibration system for the measurement error of an instrument current transformer in a parallel circuit scenario is provided, comprising: an action compensation device deployment module, a compensation device action indicator construction module, and an online calibration module;

[0056] The motion compensation device deployment module is used to dynamically adjust the equivalent impedance of the line based on the motion compensation device deployed on the parallel line, change the current shunting ratio of the parallel line, and thus disrupt the current symmetry of the parallel line.

[0057] The compensation device action indicator construction module is used to construct an index characterizing the current correlation characteristics between two parallel lines based on the current of two lines in the parallel line, and to construct a compensation device action indicator to indicate the working status of the action compensation device based on the index.

[0058] The online calibration module is used to determine the moment when the current symmetry of the parallel line is broken based on the operation indicator of the compensation device, establish a current transformer measurement error solving equation based on the measurement data before and after the symmetry breakage moment, solve for the measurement error of the current transformer, and perform online calibration of the current transformer based on the measurement error.

[0059] This invention provides an online calibration method and system for instrument current transformer (CT) measurement errors in parallel line scenarios. It proposes a solution approach that disrupts the current symmetry between parallel lines to ensure the problem's solvability. The method incorporates widely deployed motion compensation devices in power systems to disrupt the current symmetry. It extracts indicators characterizing the current correlation between parallel lines and constructs an action indicator for the motion compensation device based on the temporal characteristic parameters of these indicators. It establishes measurement error solution equations based on measurement data before and after the symmetry disruption, and solves for the measurement errors. It extracts historically solved measurement errors to form an error matrix, and uses statistical methods to obtain dense regions of error distribution and determine the measurement errors of each CT. This invention solves the problem that the linear correlation of line currents in parallel line scenarios leads to unsolvable CT ME estimation equations due to insufficient column rank. It not only reduces the manpower and material costs in power outage verification but also enables real-time online sensing of CT metering performance. This solves the online calibration problem caused by the linear correlation of currents between parallel lines in actual power transmission networks, enabling real-time assessment of CT measurement performance and effectively ensuring the accuracy and reliability of critical aspects such as protection, control, and metering in power systems. Attached Figure Description

[0060] Figure 1 This invention provides a flowchart for online calibration of measurement errors of instrument current transformers in parallel circuit scenarios;

[0061] Figure 2 A schematic diagram illustrating an embodiment of a site topology provided by the present invention;

[0062] Figure 3(a) is a schematic diagram of the structure and composition of a typical fixed series compensator provided in an embodiment of the present invention;

[0063] Figure 3(b) is a schematic diagram of the structure and composition of a thyristor-controlled series capacitor provided in an embodiment of the present invention. Detailed Implementation

[0064] The principles and features of the present invention are described below with reference to the accompanying drawings. The examples given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0065] Figure 1 A flowchart of an online calibration method for measurement error of instrument current transformers in a parallel circuit scenario provided by the present invention is shown below. Figure 1 As shown, the online calibration method includes:

[0066] Step 1: Based on the motion compensation equipment deployed on the parallel lines, the equivalent impedance of the lines is dynamically adjusted to change the shunt ratio of the parallel lines, thereby disrupting the current symmetry of the parallel lines.

[0067] like Figure 2 The diagram shown is a schematic representation of an embodiment of a site topology provided by the present invention. Figure 2 Medium current transformers are installed on each transmission line on the same busbar within a substation / power plant. Lines 1 and 2 are parallel lines, and the number of current transformers configured is [number missing]. The above-mentioned current transformers satisfy the law of conservation of energy. Parallel lines refer to multiple transmission lines that share the same busbar at both ends and are erected in parallel.

[0068] Action compensation equipment refers to equipment connected in series on transmission lines that can control line impedance or current, with series compensation equipment being the representative. Series compensation equipment is widely deployed in power systems. Based on the different switching devices used, currently operational series compensation equipment is mainly divided into two categories: mechanically switched impedance type equipment and thyristor-controlled impedance type equipment. Figures 3(a) and 3(b) show schematic diagrams of the structure and composition of a typical fixed series compensator (FSC) and a thyristor-controlled series capacitor (TCSC) provided in this embodiment of the invention, respectively. The FSC is switched on and off via a disconnecting switch, and is equivalent to a constant capacitive reactance during operation. The TCSC changes the equivalent impedance of the TCR by controlling the conduction and cutoff of the thyristor SW; the fundamental steady-state impedance is a continuous function of the delay angle α.

[0069] String complement It is the core indicator for measuring the degree of compensation of transmission lines by series compensation equipment, as shown in the following formula:

[0070] 100%

[0071] in It is a series compensation device to compensate for capacitance, It is the inductive reactance of the power transmission line.

[0072] The actual series compensation value is generally between 20% and 70%, which means that the line impedance will vary within the range of 30% to 80%, thereby achieving dynamic power flow control and improving voltage stability.

[0073] During power grid operation, series compensation equipment dynamically adjusts the equivalent impedance of the lines. Symmetry refers to the fact that for parallel lines, the current is shunted according to the impedance parameters of each circuit, and the shunting ratio remains relatively stable. Therefore, the line currents exhibit a linear correlation characteristic, exhibiting symmetry. The disruption of symmetry occurs when the series compensation equipment dynamically adjusts the equivalent impedance of the lines, thereby changing the current shunting ratio of the parallel lines. The original linear correlation characteristic of the currents differs before and after the series compensation equipment operates, and the linear correlation of the currents is broken.

[0074] This application proposes a solution by disrupting the current symmetry between parallel lines to ensure the solvability of the problem. It introduces the role of action compensation devices widely deployed in power systems. These devices can dynamically adjust the equivalent impedance of the lines. By combining measurement data of different shunt ratios of parallel lines, the linear correlation characteristics of the currents between parallel lines are weakened, thereby disrupting the current symmetry and ensuring the solvability of the equations.

[0075] Step 2: Construct an index characterizing the current correlation between the two parallel lines based on the current of the two lines in the parallel line, and construct a compensation device action indicator based on the index to indicate the working status of the compensation device; the compensation device action indicator can locate the moment when the current symmetry of the parallel lines is broken online.

[0076] Step 3: Determine the moment when the current symmetry of the parallel line is disrupted based on the operation indicator of the compensation equipment. Establish the current transformer measurement error solution equation based on the measurement data before and after the symmetry disruption moment. Solve the equation to obtain the measurement error of the current transformer. Perform online calibration of the current transformer based on the measurement error.

[0077] This invention provides an online calibration method for the measurement error of instrument current transformers in parallel line scenarios. It proposes an approach to disrupt the current symmetry between parallel lines to ensure the problem is solvable. By introducing an action compensation device to achieve the disruption of symmetry, it can solve the online calibration problem caused by the linear correlation of currents between parallel lines in actual power transmission networks. It enables real-time assessment of the measurement performance of current transformers and effectively ensures the accuracy and reliability of important links such as protection, control and metering in the power system.

[0078] Example 1

[0079] Embodiment 1 of this invention is an embodiment of an online calibration method for the measurement error of an instrument current transformer in a parallel circuit scenario, more specifically, it relates to an online calibration method for the measurement error of a current transformer in a substation or power plant, combined with... Figure 1 and Figure 2 It can be seen that embodiments of this online calibration method include:

[0080] Step 1: Based on the motion compensation equipment deployed on the parallel lines, the equivalent impedance of the lines is dynamically adjusted to change the shunt ratio of the parallel lines, thereby disrupting the current symmetry of the parallel lines.

[0081] Step 2: Construct an index characterizing the current correlation between two parallel lines based on the current of the two lines in the parallel line, and construct an action indicator for the compensation device to indicate the working status of the action compensation device based on the index.

[0082] In one possible embodiment, step 2 includes:

[0083] Step 201: Extract indicators characterizing the current correlation between parallel lines. .

[0084] In the formula, and For any i-th and j-th current transformers in parallel lines, respectively... The current measurement at a given time is a phasor.

[0085] Step 202, extract indicators The amplitude and phase are used as time-series characteristic parameters:

[0086] .

[0087] .

[0088] In the formula, For phasor magnitude, The phase angle is the phasor angle.

[0089] Step 203: Construct an autoencoder model. Use the features of the temporal feature parameters to construct a modeling dataset. Train the autoencoder model based on the dataset to obtain the optimal parameters that satisfy the minimum loss function. Construct a residual threshold based on the reconstruction residuals of the autoencoder model during the training process.

[0090] In one possible embodiment, constructing the compensation device action indicator includes three stages: modeling, monitoring, and self-updating. Step 203, the process of constructing the autoencoder model, includes:

[0091] Step 20301: Extract the temporal feature parameters of the current motion compensation device under its working state to form a dataset. .

[0092] In the formula, , , The total number of time points in the dataset used for modeling.

[0093] Step 20302, construct the autoencoder model based on dataset X as follows: .

[0094] In the formula, This represents the data at time t in dataset X.

[0095] During the coding process: This is the weight matrix. For bias vectors, For activation function, These are latent variables.

[0096] During the decoding process: This is the weight matrix. For bias vectors, For activation function, To rebuild the output.

[0097] Step 20303: Construct the loss function and find the optimal parameter set that minimizes the loss function. .

[0098] In practice, the loss function can be: After training, the autoencoder model of the PCR index is obtained.

[0099] Step 20304, construct the residual threshold based on the reconstruction residual during the training process:

[0100] .

[0101] Step 204: Input the real-time current data into the autoencoder model to obtain the reconstruction residual at the current moment. Compare the reconstruction residual at the current moment with the residual threshold to obtain the judgment value of the action recognition flag bit of the compensation device's action indicator. This action recognition flag bit indicates the working status of the action compensation device.

[0102] In one possible embodiment, step 204 includes:

[0103] Step 20401: Collect real-time current data for the parallel lines. .

[0104] Step 20402: Extract the time-series feature parameters of real-time current data. The data is then fed into the trained autoencoder model to obtain the reconstructed residual at the current time step. .

[0105] Step 20403: Reconstruct the residual at the current time. With residual threshold Compare and determine the current motion compensation device identification flag. :

[0106] .

[0107] In one possible embodiment, step 204 is followed by:

[0108] Step 205, when the motion compensation device The number of consecutive data points with a value of 1 reached This indicates that the compensation equipment has entered a stable new working state, and the flag is dynamically updated. Set to 1.

[0109] Step 206, Summary Current data is collected at any time to generate a new dataset. .

[0110] Step 207: Re-model the autoencoder and determine the residual threshold limit; after the autoencoder model is updated, the flag bits will be dynamically updated. Set to 0 and continue real-time online monitoring.

[0111] In practice, the indicator uses an autoencoder model to learn the core features and potential patterns of temporal characteristic parameters. When the motion compensation device moves, causing a state switch in the PCR indicator, the autoencoder reconstruction error will increase significantly. Specifically, the motion indicator includes three stages: modeling, monitoring, and self-updating.

[0112] During long-term operation, the indicator needs to recognize the continuous and multiple actions of the compensation equipment, so a dynamic update mechanism is designed here.

[0113] Step 3: Determine the moment when the current symmetry of the parallel line is disrupted based on the operation indicator of the compensation equipment. Establish the current transformer measurement error solution equation based on the measurement data before and after the symmetry disruption moment. Solve the equation to obtain the measurement error of the current transformer. Perform online calibration of the current transformer based on the measurement error.

[0114] In one possible embodiment, step 3 includes:

[0115] Step 301: Construct the current measurement matrix for the current transformers in the same phase group. :

[0116] .

[0117] In the formula, n is the serial number of the current transformer. This indicates the number of current transformers, and T is the number of time points. This represents the current measurement value of the nth current transformer at time T, indicated by the superscript. It is the transpose symbol. This represents the current measurement value of the nth current transformer at each moment. Indicates all A matrix composed of the current measurements of each current transformer at various times.

[0118] A series compensation device (LCD) group is constructed using the in-phase current transformers of each line on the busbar within the station. The in-phase current transformers in this group satisfy the law of conservation of energy. Based on the compensation device's operation indicator, the operation identification flag of the LCD can be obtained from the data at each time point. .for At time point 1, the current measurement matrix is ​​formed by summing the in-phase group data from the current and historical times. .

[0119] Step 302, based on Kirchhoff's current law, construct the equation for solving the measurement error of the current transformer as follows:

[0120] .

[0121] In the formula, , The lines are respectively The ratio error and phase error of the current transformer.

[0122] When the line When the CT is a calibrated reference CT, .

[0123] Step 303: Use the solver to solve the measurement error equation and obtain the estimated measurement error values ​​for each current transformer.

[0124] In practice, a least squares solver can generally be used:

[0125] .

[0126] superscript , These are the symbols for conjugate transpose and inverse, respectively.

[0127] In one possible embodiment, step 3 is followed by:

[0128] Step 4: After the motion compensation device enters a stable operating condition, extract the historical measurement error data to form an error matrix. Use statistical methods to extract the dense regions of error distribution within the error matrix to determine the measurement error of each current transformer. In specific implementation, dynamically updating the flag bits can be used. This step is triggered after the motion compensation equipment enters a stable operating condition. When the dynamic update flag is set... When the value is 1, the series compensation equipment completes the switching of operating conditions and operates stably.

[0129] In one possible embodiment, step 4 includes:

[0130] Step 401: Summarize all historical data of measurement error assessment results and construct an assessment error matrix. :

[0131] .

[0132] In the formula, and They represent the first Current transformer The ratio error assessment value and phase offset assessment value of each step. Characterizing the total number of error assessments, Excludes calibrated CT errors.

[0133] Step 402, evaluate the error matrix Cluster analysis was performed to extract the cluster with the largest number of points, and the mean within the cluster was taken as the final online error calibration result.

[0134] In practice, the efficient K-Means algorithm can be used for cluster analysis, and the number of cluster points is determined by the silhouette coefficient method.

[0135] Example 2

[0136] Embodiment 2 of the present invention is an embodiment of an online calibration system for the measurement error of an instrument current transformer in a parallel circuit scenario. The embodiment of the online calibration system includes: an action compensation device deployment module, a compensation device action indicator construction module, and an online calibration module.

[0137] The motion compensation device deployment module is used to dynamically adjust the equivalent impedance of the parallel lines based on the motion compensation devices deployed on the parallel lines, thereby changing the shunt ratio of the parallel lines and disrupting the current symmetry of the parallel lines.

[0138] The compensation equipment action indicator construction module is used to construct an index characterizing the current correlation characteristics between two parallel lines based on the current of the two lines in the parallel line, and to construct a compensation equipment action indicator to indicate the working status of the compensation equipment based on the index.

[0139] The online calibration module is used to determine the moment when the current symmetry of the parallel line is broken based on the operation indicator of the compensation device, establish the current transformer measurement error solution equation based on the measurement data before and after the symmetry failure moment, solve for the measurement error of the current transformer, and perform online calibration of the current transformer based on the measurement error.

[0140] It is understood that the online calibration system for measuring current transformer measurement error in parallel circuit scenarios provided by this invention corresponds to the online calibration method for measuring current transformer measurement error in parallel circuit scenarios provided in the foregoing embodiments. The relevant technical features of the online calibration system for measuring current transformer measurement error in parallel circuit scenarios can be referred to the relevant technical features of the online calibration method for measuring current transformer measurement error in parallel circuit scenarios, and will not be repeated here.

[0141] This invention provides an online calibration method and system for instrument current transformer (CT) measurement errors in parallel line scenarios. It proposes a solution approach that disrupts the current symmetry between parallel lines to ensure the problem's solvability. The method incorporates widely deployed motion compensation devices in power systems to disrupt the current symmetry. It extracts indicators characterizing the current correlation between parallel lines and constructs a motion compensation device action indicator based on the time-series characteristic parameters of these indicators. It establishes measurement error solution equations based on measurement data before and after the symmetry disruption, and solves for the measurement errors. It extracts historically solved measurement errors to form an error matrix, and uses statistical methods to obtain dense regions of error distribution and determine the measurement errors of each CT. This solves the problem of unsolvable CT ME estimation equations due to incomplete column rank caused by linear correlation of line currents in parallel line scenarios. It not only reduces the manpower and material costs of power outage verification but also achieves real-time online sensing of CT metering performance. This addresses the online calibration challenges caused by linear correlation of currents between parallel lines in actual power transmission networks, enabling real-time assessment of CT measurement performance and effectively ensuring the accuracy and reliability of critical aspects such as protection, control, and metering in power systems.

[0142] It should be noted that the descriptions of each embodiment in the above embodiments have different focuses. For parts that are not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0143] Those skilled in the art will understand that embodiments of the present invention can be provided as methods, systems, or computer program products. Therefore, the present invention can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, the present invention can take the form of a computer program product embodied 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.

[0144] This invention is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded computer, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0145] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0146] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0147] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including both the preferred embodiments and all changes and modifications falling within the scope of the invention.

[0148] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for online calibration of measurement error of instrument current transformers in parallel circuit scenarios, characterized in that, The online calibration method includes: Step 1: Based on the motion compensation equipment deployed on the parallel lines, the equivalent impedance of the lines is dynamically adjusted to change the shunt ratio of the parallel lines, thereby disrupting the current symmetry of the parallel lines. Step 2: Construct an index characterizing the current correlation between parallel lines based on the current of any two lines in the parallel lines, and construct a compensation device action indicator based on the index to indicate the working status of the action compensation device. Step 3: Determine the moment when the current symmetry of the parallel line is broken based on the operation indicator of the compensation device; establish the current transformer measurement error solution equation based on the measurement data before and after the moment of symmetry failure; solve the measurement error of the current transformer; and perform online calibration of the current transformer based on the measurement error. Step 2 includes: Step 201: Extract indicators characterizing the current correlation between parallel lines. ; In the formula, and For any i-th and j-th current transformers in parallel lines, respectively... The measured current value at a given time; Step 202, extract the indicators The amplitude and phase are used as time-series characteristic parameters: ； ； In the formula, For phasor magnitude, The phasor phase angle; Step 203: Construct an autoencoder model. Construct a modeling dataset using the features of the time-series feature parameters. Train an autoencoder model based on the dataset to obtain the optimal parameters that satisfy the minimum loss function. Construct a residual threshold based on the reconstruction residuals of the autoencoder model during the training process. Step 204: Input the real-time current data into the autoencoder model to obtain the reconstruction residual at the current time, and compare the reconstruction residual at the current time with the residual threshold to obtain the judgment value of the action recognition flag bit of the compensation device action indicator; Step 3 includes: Step 301: Construct the current measurement matrix for the current transformers in the same phase group. : ； In the formula, n is the serial number of the current transformer. This indicates the number of current transformers, and T is the number of time points. This represents the current measurement value of the nth current transformer at time T, indicated by the superscript. It is the transpose symbol. This represents the current measurement value of the nth current transformer at each moment; A series compensation device operation identification flag can be obtained from the data at each moment based on the in-phase current transformers of each line on the busbar within the station to construct an in-phase group. ,for At time point 1, the current measurement matrix is ​​formed by summing the in-phase group data from the current and historical times. ; Step 302, based on Kirchhoff's current law, construct the equation for solving the measurement error of the current transformer as follows: ； In the formula, , The lines are respectively The ratio error and phase error of the current transformer; When the line When the CT is a calibrated reference CT, ; Step 303: Use the solver to solve the measurement error equation and obtain the estimated measurement error values ​​for each current transformer.

2. The online calibration method according to claim 1, characterized in that, The process of constructing the autoencoder model in step 203 includes: Step 20301: Extract the temporal feature parameters of the current motion compensation device in its working state to form the dataset. ; In the formula, , , Total number of time points in the dataset used for modeling; Step 20302, construct the autoencoder model based on the dataset X as follows: ; In the formula, This refers to the data at time t in dataset X; During the coding process: This is the weight matrix. For bias vectors, For activation function, As latent variables; During the decoding process: This is the weight matrix. For bias vectors, For activation function, To rebuild the output; Step 20303: Construct the loss function and find the optimal parameter set that minimizes the loss function. ; Step 20304, construct the residual threshold based on the reconstruction residual during the training process: 。 3. The online calibration method according to claim 1, characterized in that, Step 204 includes: Step 20401: Collect real-time current data for the parallel lines. ; Step 20402: Extract the time-series feature parameters of the real-time current data feature quantities. The data is then fed into the trained autoencoder model to obtain the reconstructed residual at the current time step. ; Step 20403: Reconstruct the residual at the current time. With the residual threshold Compare and determine the current motion compensation device identification flag. : 。 4. The online calibration method according to claim 1, characterized in that, Following step 204, the following also includes: Step 205, when the motion compensation device The number of consecutive data points with a value of 1 reached At that time, dynamically update the flag bit. Set to 1; Step 206, summarize the above. Current data is collected at any time to generate a new dataset. ; Step 207: Re-model the autoencoder and determine the residual threshold limit; after the autoencoder model is updated, the flag bits will be dynamically updated. Set to 0.

5. The online calibration method according to claim 1, characterized in that, Step 3 is followed by: Step 4: After the motion compensation device enters a stable operating condition, extract the historical measurement error data to form an error matrix, and use statistical methods to extract the dense region of error distribution in the error matrix to determine the measurement error of each current transformer.

6. The online calibration method according to claim 5, characterized in that, Step 4 includes: Step 401: Summarize all historical data of measurement error assessment results and construct an assessment error matrix. : ； In the formula, and They represent the first Current transformer The ratio error assessment value and phase offset assessment value of each step. Characterizes the total number of error assessments; Step 402, evaluate the error matrix. Cluster analysis was performed to extract the cluster with the largest number of points, and the mean within the cluster was taken as the final online error calibration result.

7. An online calibration system based on the online calibration method for measuring the measurement error of an instrument current transformer in a parallel circuit scenario as described in any one of claims 1-6, characterized in that, The online calibration system includes: a motion compensation device deployment module, a compensation device motion indicator construction module, and an online calibration module; The motion compensation device deployment module is used to dynamically adjust the equivalent impedance of the line based on the motion compensation device deployed on the parallel line, change the current shunting ratio of the parallel line, and thus disrupt the current symmetry of the parallel line. The compensation device action indicator construction module is used to construct an index characterizing the current correlation characteristics between two parallel lines based on the current of two lines in the parallel line, and to construct a compensation device action indicator to indicate the working status of the action compensation device based on the index. The online calibration module is used to determine the moment when the current symmetry of the parallel line is broken based on the operation indicator of the compensation device, establish a current transformer measurement error solving equation based on the measurement data before and after the symmetry breakage moment, solve for the measurement error of the current transformer, and perform online calibration of the current transformer based on the measurement error.

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