A three-phase line current wide range measurement device and method based on TMR

Abstract

The present invention discloses a three-phase line current wide range measurement device and method based on TMR, the measurement device includes a TMR mutual inductor array and a data processing unit module; the mutual inductor array is composed of M rows and 3 columns of TMR mutual inductors, and each column of mutual inductors is correspondingly arranged vertically below the three-phase line, and each row of mutual inductors has a different range; the data processing unit module calculates the three-phase line current under the corresponding range according to the data collected by each row of mutual inductors; selects a row of mutual inductors that is not over-range and has the smallest error at the current moment, and obtains the corresponding three-phase line current as the initial current; selects a row of mutual inductors that is currently over-range and has the largest range, and uses the predicted current calculated by the current to correct the initial current, and obtains the final current of the three-phase line at the current moment. The present invention maintains high-precision measurement of the three-phase line current while greatly improving the range, and solves the problem of data mutation that may occur when switching between different ranges.

Description

Technical Field

[0001] The invention belongs to the technical field of current measurement, and in particular relates to a three-phase line current wide-range measurement device and method based on TMR. Background Art

[0002] With the rapid development of smart grids and digital grids, in order to better evaluate the health status of the entire grid and monitor faults in a timely manner, more comprehensive measurement of electrical quantity information at each node of the grid is required. Traditional electromagnetic current transformers are large and difficult to install widely, while electronic current transformers (TMR transformers) based on the measurement principle of tunneling magnetoresistance (TMR) effect have the advantages of wide bandwidth, small size, safety and non-invasive measurement. They can measure line current without being connected in series, and are a hot topic in research and one of the future development directions.

[0003] The current problem is that, unlike the traditional electromagnetic transformer principle based on the principle of electromagnetic induction, the range of the electronic transformer is limited by the voltage and current range of its internal circuit elements. Its output value will not increase indefinitely with the increase of the primary current, and it cannot measure short-term overcurrent, that is, there is a signal "saturation distortion" problem. For example: a TMR transformer has a full-scale output voltage signal of 5V at a current of 1200A. If a power grid fails and the current increases to 10kA, its output is still 5V, because this has reached the maximum output capacity of the electronic current transformer, and the excess cannot be measured.

[0004] There are several technical solutions to the problem that the electronic transformer cannot measure short-term overcurrent due to "saturation distortion" of the signal caused by the measured current exceeding its rated range:

[0005] (1) Select a transformer with a larger range. For example, select a transformer with a range of 20kA for measurement, which can meet the measurement requirements of 10kA current. However, this will greatly reduce its measurement accuracy. For example, a transformer with the same accuracy of 0.5 has two specifications with rated ranges of 1200A and 20kA. Their maximum measurement errors are Δ2=1200×±0.5%=±6A and Δ1=20kA×±0.5%=±100A, respectively. Figure 1As shown in the figure, the maximum measurement error Δ1 of the large range is much higher than the maximum measurement error Δ2 of the small range. Therefore, when the line current is small, both ranges of the transformer can measure normally, but the noise level of the large range transformer is obviously higher. Simply switching to a large range electronic transformer will lead to a serious decrease in accuracy, so that in most of the non-fault moments, the measurement error (uncertainty) of the normal operating current (about 100~500A) increases, for example, from 300A±6A to 300A±100A, which is not allowed and will lead to inaccurate measurement and erroneous operation of protection devices.

[0006] (2) Simply using two sets of transformers with different ranges, that is, 1200A and 20kA transformers for combined measurement, will output two sets of signals. However, traditional measuring devices, mechanical instruments, etc. cannot actively distinguish when to use low-range or high-range transformers. Existing technologies cannot handle the measurement value error at the moment of range switching. Sudden changes in current measurement values ​​can easily lead to false operation of protection devices, and cannot meet the requirements of large range and high precision at the same time. Figure 2 As shown in the figure, it can be seen from the arrow that when the current range is saturated and directly switched to the large-range transformer Kun, the measured value will have a current mutation. For example, the enlarged figure shown in the small window shows that when the 1200A transformer is saturated and automatically switched to the 20kA transformer measurement value, the final output signal will have a large numerical mutation, and the burr can be as high as 1500A, which poses a risk of false protection.

[0007] (3) Improve the structure of the internal components of the transformer to improve the measurement accuracy of the large-range 20kA transformer chip, that is, reduce the transformer noise and improve the accuracy of the analog-to-digital converter (ADC). This method requires too high a cost and has limited improvement capabilities. From the perspective of improving the accuracy of the analog-to-digital converter (ADC), the current 12-bit ADC resolution is 4096 levels, and the use of a 16-bit ADC can be increased to 65536 levels, which increases the measurement accuracy by 16 times. Although there is a significant improvement, the high-speed (10MHz) high-precision ADC suitable for TMR electronic transformers is expensive. The price of a single chip has increased from 20 yuan to 500 yuan, which is far higher than the price of the tunnel magnetoresistance current sensitive chip itself. More importantly, from the perspective of reducing transformer noise, the power system itself is a complex environment with high voltage and strong electromagnetic interference. Relying on interference shielding cannot completely solve the problem (that is, when the current induction intensity of the measured line is less than the internal circuit noise of the transformer, no matter how high the resolution of the measurement system is, it cannot distinguish between noise and current).

[0008] In summary, there is currently no good way to solve the problem of high-precision range expansion of tunnel magnetoresistance electronic transformers. The demand for high-precision measurement of various advanced algorithms in new power systems is rapidly increasing. How to achieve high precision while measuring a wide range of electronic transformers is an extremely important issue and has become a key issue hindering its application. Summary of the invention

[0009] The present invention provides a three-phase line wide-range current measurement device and method based on TMR, which can significantly improve the range while maintaining high accuracy, and solve the problem of data mutation that may occur when switching between different ranges.

[0010] In order to achieve the above technical objectives, the present invention adopts the following technical solutions:

[0011] A three-phase line current wide range measurement device based on TMR, comprising a TMR mutual inductor array and a data processing unit module;

[0012] The TMR mutual inductor array is composed of M rows and 3 columns of TMR mutual inductors, and each column of TMR mutual inductors is correspondingly arranged vertically below the three-phase line, and each row uses a TMR mutual inductor of a corresponding range; wherein M≥2;

[0013] The data processing unit module is used to: calculate the three-phase line current under the corresponding range according to the data collected by each row of TMR mutual inductors; select the three-phase line current corresponding to the row of TMR mutual inductors that is not over-range and has the smallest error value at the current moment from the three-phase line current under each range, and record it as the initial current of the three-phase line; select the row of TMR mutual inductors that is over-range and has the largest range at the current moment from the TMR mutual inductors of each range, use the historical three-phase line current calculated by the row of TMR mutual inductors to correct the initial current of the three-phase line at the current moment, and obtain and use it as the final current of the three-phase line at the current moment; if there is no TMR mutual inductor that exceeds the range at the current moment, then directly use the initial current of the three-phase line as the final current of the three-phase line at the current moment.

[0014] Furthermore, each row of TMR transformers calculates the three-phase line current under the corresponding range, which is expressed as:

[0015]

[0016]

[0017] In the formula, Calculate the currents of the three-phase lines A, B, and C for the mth row of TMR transformers respectively; is the sensitivity coefficient of the mth row of TMR transformers; is the magnetic permeability coefficient; are the collected data output values ​​of the TMR transformers in the mth row, 1st, 2nd, and 3rd columns respectively; are the angles formed clockwise from the positive direction of the x-axis between the A-phase line and the TMR transformers in the mth row, 1st, 2nd, and 3rd columns, respectively. are the angles formed clockwise from the x-axis between the B-phase line and the TMR transformers in the mth row, 1st, 2nd, and 3rd columns, respectively. are the angles formed clockwise from the x-axis between the C-phase line and the TMR transformers in the 1st, 2nd, and 3rd columns of the mth row; is the decoupling coefficient matrix of the transformer in the mth row, where They represent the transformation ratio coefficients between the A-phase line and the TMR transformers in the mth row, 1st, 2nd, and 3rd columns, respectively. They represent the transformation ratio coefficients between the B-phase line and the TMR transformers in the mth row, 1st, 2nd, and 3rd columns, respectively. They respectively represent the transformation ratio coefficients between the C-phase line and the TMR transformers in the 1st, 2nd and 3rd columns of the mth row; wherein, the three-phase lines are A-phase, B-phase and C-phase from left to right, and the TMR transformers vertically below the A, B and C-phase lines are numbered in the 1st, 2nd and 3rd columns respectively, and the direction from left to right is the positive direction of the x-axis.

[0018] Furthermore, all TMR transformers have the same sensitivity, and the larger the range, the larger the error value.

[0019] Furthermore, the row of TMR mutual inductors that exceeds the range and has the largest range at the current moment is selected, and the historical three-phase line current calculated is used to correct the initial current of the three-phase line at the current moment, and the final current of the three-phase line at the current moment is obtained and output, which is specifically:

[0020] Sort the TMR transformers in each row in order from small to large according to the error value. , suppose the TMR transformer with the largest range and exceeding the current range is The TMR transformer that has not exceeded the range and has the smallest error value at the current moment is the first line; set TMR transformer from The moment starts to exceed the range;

[0021] Use The TMR transformer collects The three-phase line current at several moments before the moment is used to make rolling predictions from Started from time to time, continuous Any P-phase line current at a total of k sampling points within the time length , and obtain a series of predicted short-term current time series , , is the sampling rate of the data processing unit, and the arbitrary P phase is A phase, B phase or C phase;

[0022] Using forecasted short-term current time series , for The TMR transformer is used to measure Started from time to time, continuous The three-phase line current sequence of k sampling points in the time length To make corrections:

[0023]

[0024] In the formula, To correct the P-phase line current at time t, that is, the final P-phase line current at the current time to be output; is a time-varying weight, and , .

[0025] Furthermore, only Continuous start of time The initial current of the three-phase line at k sampling points within the time length is corrected, and the time length satisfy ; The final current of the three-phase line at the next moment is taken as The three-phase line current is measured by the TMR transformer.

[0026] Furthermore, if there is no TMR transformer with an over-range at the current moment, there is no TMR transformers are used, and thus there is no predictable short-term current time series , so the final current of the P-phase line at the current moment to be output is , directly take the value as the P-phase line current measured by the TMR transformer in the first row ,Right now .

[0027] A three-phase line current wide range measurement method based on TMR, comprising:

[0028] A row of M TMR transformers is arranged vertically below the three-phase line, and an array of M rows and 3 columns of TMR transformers constitutes a data acquisition module, and each row uses a TMR transformer of a corresponding range; wherein M≥2;

[0029] Each TMR transformer collects data and uploads it to the data processing unit;

[0030] The data processing unit completes the following processes:

[0031] (1) Calculate the three-phase line current under the corresponding range based on the data collected by each row of TMR transformers;

[0032] (2) From the three-phase line currents under each range, select the three-phase line current corresponding to a row of TMR transformers that is within the range and has the smallest error value at the current moment, and record it as the initial three-phase line current;

[0033] (3) From the TMR transformers of each range, select a row of TMR transformers that are out of range and have the largest range at the current moment, use the historical three-phase line current calculated by the transformer to correct the initial current of the three-phase line at the current moment, and obtain the final current of the three-phase line at the current moment;

[0034] (4) If there is no TMR transformer with out-of-range current at the current moment, the initial current of the three-phase line is directly used as the final current of the three-phase line at the current moment.

[0035] Compared with the prior art, this application has the following beneficial effects:

[0036] (1) The measurement method and device of the present invention solve the problem of data mutation caused by different minimum resolutions when switching between different ranges of the electronic transformer, and combine the data of the electronic transformer of two adjacent ranges for accurate measurement, thereby improving the accuracy and stability of current measurement.

[0037] (2) The present invention adopts a regression prediction model based on a long short-term memory network (LSTM). In the selection of training input data, in addition to the known actual current data as input, time series and sine wave sequences are added as auxiliary regression parameters to enhance the learning effect, making the training accuracy higher and the prediction more accurate.

[0038] (3) The present invention fully considers the objective law that the deviation between the predicted value and the actual value gradually increases, and adopts the time-varying weight method to correct the measured value, so that the weight of the predicted data decreases over time, and the final output measured current value smoothly transitions to the measurement data of the next range transformer.

[0039] (4) The present invention improves the measuring range of the TMR electronic transformer without losing accuracy. The greater the number of measuring ranges, the higher and more stable the measurement data accuracy is, which helps the normal and stable operation of the power system protection and control device and expands the application scope of the electronic transformer. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a comparison chart of measurement errors of transformers with different ranges;

[0041] Figure 2 It is the current mutation phenomenon that occurs when the low-range transformer is directly switched to the high-range after saturation;

[0042] Figure 3 This is a step diagram of the wide-range current measurement method for three-phase circuits of the present application;

[0043] Figure 4 This is a schematic diagram of the installation of the TMR transformer array of this application;

[0044] Figure 5 This is the structure diagram of the LSTM regression prediction model of this application;

[0045] Figure 6 1 is a comparison diagram of the effects of the traditional method and the method of the present application, wherein (a) represents the traditional method and (b) represents the method of the present application;

[0046] Figure 7 This is a connection diagram of the wide-range current measuring device for three-phase circuits of the present application. DETAILED DESCRIPTION

[0047] The following is a detailed description of an embodiment of the present invention. This embodiment is based on the technical solution of the present invention, and provides a detailed implementation method and a specific operation process to further explain the technical solution of the present invention.

[0048] This embodiment provides a three-phase line current wide range measurement method based on TMR, including installing a TMR transformer array and collecting and processing the three-phase line current. Figure 3 shown.

[0049] 1. Install the TMR transformer array.

[0050] A row of M TMR transformers is arranged vertically below the three-phase line, and an array of M rows and 3 columns of TMR transformers constitutes a data acquisition module, and each row adopts a TMR transformer of a corresponding range; wherein M≥2.

[0051] TMR electronic transformers are installed in an array of M rows and three columns, and the relative position is measured to obtain parameters such as length and angle for subsequent magnetic field decoupling and range calculation. This step is to enable M rows of TMR electronic transformers to measure the coupled magnetic field signals generated by the A / B / C three-phase line currents in the environmental space. Each electronic transformer independently outputs an analog signal of -5V~+5V, and the output value is a variable matrix U related to the spatial magnetic field intensity (M×3 order, M≥2, physical quantity unit: volt V, any element in the matrix can be mapped to the output value of a TMR electronic transformer in the actual scene):

[0052]

[0053] According to the relative position of the transformer and the conductor of the measured line when installed, combined with the Biot-Savart Law, the magnetic field at the location of three TMR transformers in a row of the array is obtained. Any element has the following coupling relationship with the current of the three-phase line under test. Taking the TMR transformer corresponding to the (m,2) element as an example, it is simultaneously affected by the magnetic field of the three-phase measured line, such as Figure 4 As shown by the dotted line in It is expressed as:

[0054]

[0055] Where: is the sensitivity coefficient of the mth row TMR transformer, which has a constant value; is the magnetic permeability coefficient, whose value is ; is the current to be measured in phase A; is the angle between the A-phase conductor and the (m,2) transformer clockwise from the x-axis; Represents the transformation ratio between the A-phase conductor and the (m,2) transformer; A can also be B or C.

[0056] 2. The TMR transformer collects data and uploads it to the data processing unit for processing to obtain the three-phase line current.

[0057] The output value of the TMR transformer is uploaded to the data processing unit module, where it is converted from analog to digital and cached in a first-in-first-out queue (FIFO) for subsequent algorithm processing and use.

[0058] After receiving the data collected by each TMR transformer, the data processing unit module completes the following process:

[0059] Step 1: Calculate the three-phase line current under the corresponding range according to the data collected by each row of TMR transformers.

[0060] Solve the decoupling equation between the TMR electronic transformer array and the primary line current so that the three columns of electronic transformers in each row correspond to the single magnetic field generated by the three-phase line current (that is, the value of each column element is only affected by the change of the measured line current in this column, rather than the initial three-phase coupled magnetic field). According to the relative position of the transformer and the measured conductor when installed, the decoupling coefficient matrix K of any m-th row of transformers is calculated. m (3×3 order, physical quantity unit: volt per ampere V / A).

[0061]

[0062] Further derivation of the equations yields the three-phase current measured by the output values ​​of the TMR transformers in the mth row: , , for:

[0063]

[0064] The TMR electronic transformers installed in an array of M rows and three columns can correspondingly solve the three-phase line currents measured by M groups of transformers with different ranges.

[0065] Step 2: From the three-phase line currents under each range, select the three-phase line current corresponding to a row of TMR transformers that is not out of range and has the smallest error value at the current moment, and record it as the initial three-phase line current.

[0066] All TMR transformers have the same sensitivity, and the minimum noise is positively correlated with the transformer range, that is, the larger the range, the larger the error value caused by the background noise. Therefore, a row of TMR transformers with the smallest error value (that is, the smallest noise) is selected from each row of TMR transformers that are not currently over-range, and the three-phase line current calculated corresponding to this row of TMR transformers is recorded as the initial current of the three-phase line.

[0067] Step 3, from the TMR transformers of each range, select a row of TMR transformers that are out of range and have the largest range at the current moment, use the historical three-phase line current calculated by them to correct the initial current of the three-phase line at the current moment, and obtain and use it as the final current of the three-phase line at the current moment.

[0068] When the current measured by the low-range transformer reaches saturation at a certain moment, it is necessary to switch to a transformer with a larger range. However, suddenly switching from a transformer with a smaller range to a transformer with a larger range may cause data mutation problems. However, based on the principle that the magnetic field cannot mutate, that is, the current cannot mutate, the measured three-phase line current should have a characteristic trend in a short period of time to keep it continuous. The embodiment of the present invention adopts a regression prediction model based on the long short-term memory network LSTM (Long Short-Term Memory). In particular, considering that the AC power system presents a significant periodic variation law, the fundamental sinusoidal current signal is used as an auxiliary parameter to enhance the learning effect. Then, the data when the transformer is not saturated and distorted is used for rolling learning correction to find the characteristic trend in the current time series data.

[0069] When the current measured by the low-range transformer is saturated and distorted at a certain moment, that is, it exceeds the range, the embodiment of the present invention adopts a regression prediction model based on the long short-term memory network LSTM to predict the current signal in the short term of the subsequent several sampling points, and uses this predicted short-term current signal as the correction amount of the initial current of the three-phase line. At the same time, the objective law that the deviation between the predicted value and the actual value gradually increases is taken into account, and the measured value is corrected by time-varying weights (the specific correction method and the time-varying weight method are explained in Chapter 5). This can reduce the measurement error of the high-range transformer, that is, reduce the sudden change of the value of the transformer in the next gear range.

[0070] The regression prediction model based on the long short-term memory network LSTM, such as Figure 5 As shown in Figure 1, it includes input layer, LSTM layer, activation layer, fully connected layer and output layer. The LSTM layer is composed of input gate , Forget Gate , output gate composition , the calculation methods at time t are:

[0071]

[0072]

[0073]

[0074] Where: ReLU (Rectified Linear Unit) is the ramp activation function , W is the weight matrix of the corresponding gate, is the output of the previous moment, is the output at the current moment, and b is the bias term of the corresponding gate.

[0075] LSTM layer memory unit for loop parameter transmission And the current time output The calculation methods are:

[0076]

[0077] Where: tanh is the hyperbolic tangent activation function .

[0078] Before using the LSTM regression prediction model to predict short-term current signals, the model is trained first: the training set and test set data are input into the model, and each layer calculates and outputs the data in turn, which is compared with the test set data. After reaching the preset step size, the trained LSTM regression prediction model is exported.

[0079] Sort the TMR transformers in each row in order from small to large according to the error value. , suppose the TMR transformer with the largest range and exceeding the current range is The TMR transformer that has not exceeded the range and has the smallest error value at the current moment is the first OK.

[0080] Assume that the time when the low-range transformer measuring current saturation (i.e., the output value reaches its maximum or minimum output value, i.e., exceeds the range) in row a and column 2 (phase B) is t0, and use the LSTM model trained with the data of the previous moment for autoregressive prediction. The predicted current value is used as the last value of the next round of input data. After k consecutive predictions, a series of predicted short-term current time series is obtained. .

[0081] The predicted short-term current time series As the Transformer continuous k sampling points in the time length ( ) of the measurement series The correction amount, f s is the sampling rate of the data processing unit. At the same time, considering the objective law that the deviation between the predicted value and the actual value gradually increases, the time-varying weight p is used to The measured value sequence of k sampling points of the row transformer The correction is performed to obtain the three-phase line current at time t, that is, the final three-phase line current to be output at the current time. The correction calculation method is:

[0082]

[0083] Extended to the actual measured current value of any column of the TMR electronic transformer installed in an array of M rows and three columns, it is:

[0084]

[0085] In the formula, To correct the P-phase line current at time t, that is, the final P-phase line current at the current time to be output; is a time-varying weight, and , .

[0086] Where: P can be phase A, phase B or phase C; r m is the range of the transformer in the mth layer; t0 is the moment when the transformer is saturated, and the value will be updated when each row of transformers is saturated; k is the number of sampling points for backward prediction, f s is the sampling rate of the data processing unit. In order to ensure the prediction range expansion effect and avoid overfitting, its value has a constraint relationship , that is, the predicted waveform length should be less than or equal to 1% of the power frequency current cycle. For example, if the sampling rate of the data processing unit is ,but .

[0087] Following this formula can reduce the sudden change in value when switching to the next range transformer.

[0088] For example, when M=2, the low-range transformer range r1 is 1200A, and the high-range transformer range r2 is 20kA. When the current suddenly increases, the phase line current wide-range measurement method of the present invention is compared with the measurement effect of the traditional direct switching to the next range transformer, such as Figure 6 As shown, the standard deviation coefficient of the traditional method when switching the range is 75.49, while the standard deviation coefficient of the method proposed in the present invention is only 57.53, and the data fluctuation caused by the measurement error is smaller, which proves that the measurement accuracy of the method of the present invention has a better effect.

[0089] Step 4: If there is no TMR transformer with out-of-range at the current moment, the initial current of the three-phase line is directly used as the final current of the three-phase line at the current moment.

[0090] This embodiment provides a three-phase line current wide range measurement device based on TMR, including a TMR transformer array data processing unit module, such as Figure 7 shown.

[0091] The TMR transformer array is composed of M rows and 3 columns of TMR transformers, and each column of TMR transformers is correspondingly arranged vertically below the three-phase line, and each row adopts a TMR transformer of a corresponding range; wherein M≥2; the array-mounted TMR transformers measure the coupled magnetic field signals generated by the A / B / C three-phase lines in the environmental space in real time, and each electronic transformer independently outputs an analog signal of -5V~+5V, and the output signal is connected to the data processing unit module through a coaxial cable.

[0092] The data processing unit module is composed of an analog-to-digital converter (ADC), a field programmable gate array (FPGA), a random access memory (RAM), a physical layer port controller (PHY), and a power management module, and is used to: (1) convert the received analog signal into a digital signal; (2) calculate the three-phase line current under the corresponding range based on the data collected by each row of TMR transformers; (3) select the three-phase line current corresponding to the row of TMR transformers that is not out of range at the current moment and has the smallest error value from the three-phase line current under each range , recorded as the initial current of the three-phase line; (4) From the TMR transformers of each range, select a row of TMR transformers that are out of range and have the largest range at the current moment, use the historical three-phase line current calculated by them to correct the initial current of the three-phase line at the current moment, and obtain and use it as the final current of the three-phase line at the current moment; (5) If there is no TMR transformer that is out of range at the current moment, directly use the initial current of the three-phase line as the final current of the three-phase line at the current moment; (6) The final current of the three-phase line is output as a digital quantity through optical fiber or Ethernet for use by the subsequent equipment of the power system.

[0093] Among them, the analog-to-digital converter (ADC) converts the analog signal output by the transformer into a digital signal that can be accessed by the computer.

[0094] Field Programmable Gate Array (FPGA): Data processing and control chip used for learning and training normal current and predicting saturation current, calculating and outputting the final current value.

[0095] Random Access Memory (RAM): quickly accesses waveform data and caches waveform data in a first-in, first-out queue (FIFO) for use by algorithms within the FPGA.

[0096] Physical layer port controller (PHY): Packs the final current signal output by the FPGA, sends it quickly through optical fiber or Ethernet, and verifies data with the receiving end.

[0097] Power management module: controls and distributes power supply to ensure stable operation of each part.

[0098] The above embodiments are preferred embodiments of the present application. Ordinary technicians in this field can also make various changes or improvements on this basis. Without departing from the overall concept of the present application, these changes or improvements should fall within the scope of protection required by the present application.

Claims

1. A three-phase line current wide range measurement device based on TMR, characterized in that: It includes a TMR mutual inductor array and a data processing unit module; The TMR mutual inductor array is composed of M rows and 3 columns of TMR mutual inductors, and each column of TMR mutual inductors is correspondingly arranged vertically below the three-phase line, and each row uses a TMR mutual inductor of a corresponding range; wherein M≥2; The data processing unit module is used to: calculate the three-phase line current under the corresponding range according to the data collected by each row of TMR mutual inductors; select the three-phase line current corresponding to the row of TMR mutual inductors that is not over-range and has the smallest error value at the current moment from the three-phase line current under each range, and record it as the initial current of the three-phase line; select the row of TMR mutual inductors that is over-range and has the largest range at the current moment from the TMR mutual inductors of each range, use the historical three-phase line current calculated by the row of TMR mutual inductors to correct the initial current of the three-phase line at the current moment, and obtain and use it as the final current of the three-phase line at the current moment; if there is no TMR mutual inductor that is over-range at the current moment, directly use the initial current of the three-phase line as the final current of the three-phase line at the current moment; Each row of TMR transformers calculates the three-phase line current under the corresponding range, expressed as: ； ； In the formula, Calculate the currents of the three-phase lines A, B, and C for the mth row of TMR transformers respectively; is the sensitivity coefficient of the mth row of TMR transformers; is the magnetic permeability coefficient; are the collected data output values ​​of the TMR transformers in the mth row, 1st, 2nd, and 3rd columns respectively; are the angles formed clockwise from the positive direction of the x-axis between the A-phase line and the TMR transformers in the mth row, 1st, 2nd, and 3rd columns, respectively. are the angles formed clockwise from the x-axis between the B-phase line and the TMR transformers in the mth row, 1st, 2nd, and 3rd columns, respectively. are the angles formed clockwise from the x-axis between the C-phase line and the TMR transformers in the m-th row, the 1st, 2nd, and 3rd columns; is the decoupling coefficient matrix of the mth row transformer, where They represent the transformation ratio coefficients between the A-phase line and the TMR transformers in the mth row, 1st, 2nd, and 3rd columns, respectively. They represent the transformation ratio coefficients between the B-phase line and the TMR transformers in the mth row, 1st, 2nd, and 3rd columns, respectively. They represent the transformation ratio coefficients between the C-phase line and the TMR transformers in the 1st, 2nd and 3rd columns of the mth row, respectively; wherein the three-phase lines are A-phase, B-phase and C-phase from left to right, and the TMR transformers vertically below the A-phase, B-phase and C-phase lines are numbered in the 1st, 2nd and 3rd columns, respectively, and the direction from left to right is the positive direction of the x-axis; All TMR transformers have the same sensitivity, and the larger the range, the greater the error value; The method selects a row of TMR transformers that are out of range and have the largest range at the current moment, and uses the calculated historical three-phase line current to correct the initial current of the three-phase line at the current moment, and obtains and outputs the final current of the three-phase line at the current moment, which is specifically: Sort the TMR transformers in each row in order from small to large according to the error value. , suppose the TMR transformer with the largest range and exceeding the current range is The TMR transformer that has not exceeded the range and has the smallest error value at the current moment is the first line; set TMR transformer from The moment starts to exceed the range; Use The TMR transformer collects The three-phase line current at several moments before the moment is used to make rolling predictions from Started from time to time, continuous Any P-phase line current at a total of k sampling points within the time length , and obtain a series of predicted short-term current time series , , is the sampling rate of the data processing unit, and the arbitrary P phase is A phase, B phase or C phase; Using forecasted short-term current time series , for The TMR transformer is used to measure Started from time to time, continuous The three-phase line current sequence of k sampling points in the time length To make corrections: ； In the formula, To correct the P-phase line current at time t, that is, the final P-phase line current at the current time to be output; is a time-varying weight, and , .

2. The three-phase line current wide-range measuring device based on TMR according to claim 1, characterized in that: Only from Continuous start of time The initial current of the three-phase line at k sampling points within the time length is corrected, and the time length satisfy ; The final current of the three-phase line at the next moment is taken as The three-phase line current is measured by the TMR transformer.

3. The three-phase line current wide-range measuring device based on TMR according to claim 1, characterized in that: If there is no TMR transformer with over-range at the current moment, there is no TMR transformers are used, and thus there is no predictable short-term current time series , so the final current of the P-phase line at the current moment to be output is , directly take the value as the P-phase line current measured by the TMR transformer in the first row ,Right now .

4. A three-phase line current wide range measurement method based on TMR, characterized in that: include: A row of M TMR transformers is arranged vertically below the three-phase line, and an array of M rows and 3 columns of TMR transformers constitutes a data acquisition module, and each row uses a TMR transformer of a corresponding range; wherein M≥2; Each TMR transformer collects data and uploads it to the data processing unit; The data processing unit completes the following processes: (1) Calculate the three-phase line current under the corresponding range based on the data collected by each row of TMR transformers; (2) From the three-phase line currents under each range, select the three-phase line current corresponding to a row of TMR transformers that is within the range and has the smallest error value at the current moment, and record it as the initial three-phase line current; (3) From the TMR transformers of each range, select a row of TMR transformers that are out of range and have the largest range at the current moment, use the historical three-phase line current calculated by the transformer to correct the initial current of the three-phase line at the current moment, and obtain the final current of the three-phase line at the current moment; (4) If there is no TMR transformer with over-range at the current moment, the initial current of the three-phase line is directly used as the final current of the three-phase line at the current moment; Each row of TMR transformers calculates the three-phase line current under the corresponding range, expressed as: ； ； In the formula, Calculate the currents of the three-phase lines A, B, and C for the mth row of TMR transformers respectively; is the sensitivity coefficient of the mth row of TMR transformers; is the magnetic permeability coefficient; are the collected data output values ​​of the TMR transformers in the mth row, 1st, 2nd, and 3rd columns respectively; are the angles formed clockwise from the positive direction of the x-axis between the A-phase line and the TMR transformers in the mth row, 1st, 2nd, and 3rd columns, respectively. are the angles formed clockwise from the x-axis between the B-phase line and the TMR transformers in the mth row, 1st, 2nd, and 3rd columns, respectively. are the angles formed clockwise from the x-axis between the C-phase line and the TMR transformers in the m-th row, the 1st, 2nd, and 3rd columns; is the decoupling coefficient matrix of the mth row transformer, where They represent the transformation ratio coefficients between the A-phase line and the TMR transformers in the mth row, 1st, 2nd, and 3rd columns, respectively. They represent the transformation ratio coefficients between the B-phase line and the TMR transformers in the mth row, 1st, 2nd, and 3rd columns, respectively. They represent the transformation ratio coefficients between the C-phase line and the TMR transformers in the 1st, 2nd and 3rd columns of the mth row, respectively; wherein the three-phase lines are A-phase, B-phase and C-phase from left to right, and the TMR transformers vertically below the A-phase, B-phase and C-phase lines are numbered in the 1st, 2nd and 3rd columns, respectively, and the direction from left to right is the positive direction of the x-axis; All TMR transformers have the same sensitivity, and the larger the range, the greater the error value; The method selects a row of TMR transformers that are out of range and have the largest range at the current moment, and uses the calculated historical three-phase line current to correct the initial current of the three-phase line at the current moment, and obtains and outputs the final current of the three-phase line at the current moment, which is specifically: Sort the TMR transformers in each row in order from small to large according to the error value. , suppose the TMR transformer with the largest range and exceeding the current range is The TMR transformer that has not exceeded the range and has the smallest error value at the current moment is the first line; set TMR transformer from The moment starts to exceed the range; Use The TMR transformer collects The three-phase line current at several moments before the moment is used to make rolling predictions from Started from time to time, continuous The line current of any P-phase line at a total of k sampling points within the time length , and obtain a series of predicted short-term current time series , , is the sampling rate of the data processing unit, and the arbitrary P phase is A phase, B phase or C phase; Using forecasted short-term current time series , for The TMR transformer is used to measure Started from time to time, continuous The three-phase line current sequence at k sampling points at time To make corrections: ； In the formula, To correct the P-phase line current at time t, that is, the final P-phase line current at the current time to be output; is a time-varying weight, and , .

5. The method for measuring three-phase line current with a wide range based on TMR according to claim 4, characterized in that: Only from Started from time to time, continuous The initial current of the three-phase line at k sampling points within the time length is corrected, and the time length t satisfies ; The final current of the three-phase line at the next moment is taken as The three-phase line current is measured by the TMR transformer.

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