RLS adaptive transient current signal frequency division inversion measurement method

Abstract

The present application relates to the field of electric power. Provided is an RLS adaptive transient current signal frequency division inversion measurement method. The method comprises: firstly acquiring a full-frequency measurement characteristic curve of a current transformer; injecting test signals into the current transformer on the basis of the full-frequency measurement characteristic curve, and measuring output signals of the current transformer; training input signals and the output signals by means of using an RLS adaptive algorithm to obtain a transfer relationship between the input signals and the output signals; then establishing an inversion measurement group by means of the transfer relationship; and by means of using the inversion measurement group, performing frequency division inversion on an output signal to be inverted, so as to obtain a corrected transient current signal. The present application performs frequency division on output signals of transformers, and uses the inversion measurement group to perform inversion on signals having different frequencies, thus solving the problem of incapability of accurately acquiring transient current signals.

Description

RLS adaptive frequency division inversion measurement method for transient current signal

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on September 18, 2023, with application number 202311201393.8 and invention name “RLS adaptive transient current signal frequency division inversion measurement method”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of electric power, and in particular to an RLS adaptive transient current signal frequency division inversion measurement method. Background Art

[0003] The distribution network adopts a low-current non-effective grounding system. However, due to the frequent switching of overhead cable lines in cities and mountains, the fault types are complex and diverse. The fault characteristic transient current signal contains rich fault information. Accurately measuring this transient current information has the following benefits: accurate identification of fault type, precise location of fault, and precise line and phase selection of protection equipment.

[0004] Accurate extraction of transient current signals is key to implementing the above technologies and enhancing grid stability. Considering that existing electromagnetic current transformers (CTs) have complex winding inductance and distributed capacitance, transient signals are severely attenuated, resulting in inconsistencies between the output signal and the measured signal. Measurement and control equipment cannot obtain accurate broadband, true transient current signals of the distribution network from the output signal. This can cause power protection measurement and control equipment to fail to operate or malfunction, leading to accidents such as fires or power outages, affecting the safe and stable operation of the distribution network.

[0005] Summary of the Invention

[0006] The present application provides an RLS adaptive transient current signal frequency division inversion measurement method to solve the problem of being unable to accurately obtain transient current signals.

[0007] The present application provides an RLS adaptive transient current signal frequency division inversion measurement method, comprising:

[0008] Obtain the full-frequency measurement characteristic curve of the current transformer;

[0009] injecting a test signal into the current transformer according to the full-band measurement characteristic curve, and measuring an output signal of the current transformer;

[0010] Using an RLS adaptive algorithm to train the input signal and the output signal to obtain a transfer relationship between the input signal and the output signal;

[0011] Establishing an inversion measurement group through the transfer relationship;

[0012] The inversion measurement group is used to perform frequency division inversion on the output signal to be inverted to obtain a modified transient current signal.

[0013] Optionally, the test signal is an alternating current signal of different frequencies; the method further includes:

[0014] Generate multiple samples using the current transformer input signal and output signal at different frequencies, each sample corresponding to an RLS adaptive filter, the sample including the output signal to be inverted and the input signal as the desired signal;

[0015] A plurality of the samples are input into an RLS adaptive filter to calculate an estimated output signal, and the estimated output signal is used to calculate an RLS error signal.

[0016] Optionally, the method further includes:

[0017] inputting the output signal and the input signal at a first frequency into the RLS adaptive filter;

[0018] Calculating a vector composed of the input signal at the first moment as a first vector; calculating a coefficient vector composed of the RLS adaptive filter weights at the first moment as a second vector;

[0019] Calculate an estimated output signal at a first moment using the first vector and the second vector;

[0020] The difference between the estimated output signal and the input signal as the desired signal is calculated to obtain an RLS error signal.

[0021] Optionally, the method further includes:

[0022] generating an autocorrelation matrix of the input signal;

[0023] Calculating the inverse matrix of the autocorrelation matrix;

[0024] The inverse matrix is ​​recursively calculated to obtain coefficient update equations of the RLS adaptive filter at a first moment and a moment next to the first moment.

[0025] Optionally, the method further includes:

[0026] performing iterative updating on the second vector using the coefficient updating equation to obtain updated data;

[0027] Correcting the estimated output signal at a second moment using a recursive algorithm based on the updated data to obtain parameter estimates and a corrected estimated output signal, wherein the second moment is earlier than the first moment;

[0028] Calculating an estimation error using the estimated output signal and the corrected estimated output signal;

[0029] If the estimated error is within the error threshold, the second vector at the first moment is stored.

[0030] Optionally, establishing the inversion measurement group through the transfer relationship further includes:

[0031] Establishing an RLS training group based on the transmission relationship between the input signal and the output signal at different frequencies;

[0032] An inversion measurement set is established through the RLS training set, wherein the inversion measurement set includes the parameter estimation values ​​at different frequencies.

[0033] Optionally, the method further includes:

[0034] receiving a measurement signal output by the current transformer;

[0035] Screening out distorted signals from the measurement signal;

[0036] Using short-time Fourier transform to divide the frequency of the distorted signal to obtain signals of different frequencies;

[0037] inputting the signals of different frequencies into the inversion measurement group;

[0038] Obtaining the estimated output signals at different frequencies according to the parameter estimation values ​​at different frequencies;

[0039] The estimated output signals of different frequencies are summed to obtain a corrected transient current signal.

[0040] Optionally, the method further includes:

[0041] detecting the amplitude of the corrected transient current signal;

[0042] If the signal output amplitude is equal to the preset range, the gain is switched using an automatic variable range algorithm to expand the range.

[0043] Optionally, the method further includes:

[0044] measuring a measurement signal output by the current transformer;

[0045] converting the measurement signal into a voltage signal;

[0046] If the voltage signal amplitude is less than the maximum output voltage value of the preset ratio, the range is restored to the preset range.

[0047] Optionally, the method further includes:

[0048] detecting whether the measuring range is an expanded measuring range or a preset measuring range;

[0049] If the measuring range is the extended measuring range, a high level signal is output, and the high level signal is defined as a temporary modified ratio;

[0050] If the measuring range is the preset measuring range, a low-level signal is output, and the low-level signal is defined as restoring the transformation ratio to an initial value.

[0051] The present application provides an RLS adaptive transient current signal frequency division inversion measurement method, the method comprising: first obtaining a full-band measurement characteristic curve of a current transformer; then injecting a test signal into the current transformer according to the full-band measurement characteristic curve, and measuring the output signal of the current transformer; using an RLS adaptive algorithm to train the input signal and the output signal to obtain a transfer relationship between the input signal and the output signal; then establishing an inversion measurement group based on the transfer relationship; using the inversion measurement group to perform frequency division inversion on the output signal to be inverted to obtain a corrected transient current signal, and by frequency dividing the transformer output signal and inverting signals of different frequencies with the inversion measurement group, the problem of being unable to accurately obtain the transient current signal is resolved. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings:

[0053] FIG1 is a flow chart of an RLS adaptive transient current signal frequency division inversion measurement method according to an embodiment;

[0054] FIG2 is a schematic diagram of an output signal that needs to be inverted, shown in one embodiment;

[0055] FIG3 is a schematic diagram of an input signal as a desired signal according to an embodiment;

[0056] FIG4 is a schematic diagram showing the flow of output signals and input signals according to an embodiment;

[0057] FIG5 is a schematic diagram of the coefficient update equation calculation process;

[0058] FIG6 is a schematic diagram of an inversion measurement group according to an embodiment;

[0059] FIG7 is a schematic diagram of a signal inversion unit according to an embodiment;

[0060] FIG8 is a schematic diagram of outputting a corrected transient current signal according to an embodiment;

[0061] FIG9 is a schematic diagram showing a case where an output signal requiring inversion is clipped and distorted according to an embodiment;

[0062] FIG10 is a schematic diagram of an output signal processed by an adaptive variable range module according to an embodiment;

[0063] FIG11 is a schematic diagram showing the connection between the adaptive variable range module and the signal inversion unit according to an embodiment. DETAILED DESCRIPTION

[0064] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0065] To address the high-frequency attenuation and signal distortion issues that occur with transient current signals after being measured by current transformers, there are several methods to improve the transient current measurement accuracy of current transformer signals: The first method involves optimizing the structure of the current transformer equipment to reduce the influence of winding inductance and distributed capacitance. For example, the Rogowski coil transformer eliminates the iron core, allowing for the measurement of higher-frequency transient current signals; the optical current transformer eliminates the conductor winding, increasing the measurement bandwidth. These methods require precise modeling of the current transformer or changes to its basic measurement principles and performance. Rogowski coil transformers have difficulty measuring low-frequency signals, resulting in reduced measurement accuracy for important power frequency quantities, sacrificing some power frequency accuracy in exchange for transient current measurement performance; the manufacturing process for optical current transformers is complex and costly, and they are mostly used for current measurement in transmission networks.

[0066] The second category is the optimization of current transformer measurement algorithms. This method uses intelligent algorithms to train the characteristics of current transformers, reversely derives the high-voltage side signal from the current transformer output signal, and then outputs it. This method does not require the elimination of existing current transformers in operation. It only measures the existing output signal, analyzes and processes the output signal using learning methods such as artificial intelligence, and finally processes the signal and outputs it again. For example, the LMS algorithm uses the tap parameters of previous moments as the data block at that moment, and estimates the minimum mean square error of the squared error at the moment. It does not use the tap parameters of the current moment to re-estimate the data blocks of previous moments and the minimum cumulative squared error. Therefore, the LMS algorithm has poor adaptability to non-stationary signals.

[0067] 1 , an embodiment of the present application provides an RLS adaptive transient current signal frequency division inversion measurement method, comprising:

[0068] S100: Obtain the full-frequency measurement characteristic curve of the current transformer.

[0069] S110: injecting a test signal into the current transformer according to the full-band measurement characteristic curve, and measuring the output signal of the current transformer.

[0070] The test signal is an AC current signal of different frequencies. The method further includes: generating multiple samples using the current transformer input signal and output signal at different frequencies, each sample corresponding to an RLS adaptive filter, the sample including the output signal to be inverted and the input signal as the desired signal; inputting the multiple samples into the RLS adaptive filter to calculate an estimated output signal, wherein the estimated output signal is used to calculate the RLS error signal.

[0071] As shown in Figure 4, AC current signals of varying frequencies are injected into an optimized current transformer. The current transformer input and output signals at varying current frequencies serve as h samples, each corresponding to an RLS adaptive filter. These h samples include the output signal x(h) to be inverted and the input signal p(h), which serves as the desired signal. See Figures 2 and 3. The greater the number of current frequency points, the greater the number of samples h, resulting in better frequency division inversion. A higher upper limit on the current frequency points indicates that the optimized current sensor is better able to measure higher-frequency grid current signals.

[0072] The following method can be used to select different frequencies: The optimal measurement bandwidth of an iron-core electromagnetic current transformer is 30 to 10 kHz. To ensure that the current transformer's normal measurement is not affected in the extreme case of a signal inversion unit failure and to reduce interference with a well-performing current transformer, adaptive frequency division inversion processing can be performed on the signal starting at 10 kHz. To increase the accuracy of the traveling wave inversion model, a large number of samples can be used for training. Based on the computing and storage capabilities of the inversion unit, a step value of 1 kHz is used to control the AC current source to inject a signal between 10 kHz and 2 MHz, with h = 1990 samples.

[0073] S200: Using the RLS adaptive algorithm to train the input signal and the output signal to obtain a transfer relationship between the input signal and the output signal.

[0074] In some embodiments, the method further includes: inputting an output signal and an input signal at a first frequency into the RLS adaptive filter; calculating a vector consisting of the input signal at the first moment as a first vector; calculating a coefficient vector consisting of the RLS adaptive filter weights at the first moment as a second vector; calculating an estimated output signal at the first moment using the first vector and the second vector; and calculating a difference between the estimated output signal and the input signal as the expected signal to obtain an RLS error signal.

[0075] For example, referring to FIG5 , the first moment is set as the nth moment. After inputting x(n) and p(n) into the RLS adaptive filter, the vector consisting of the input signal at the nth moment is calculated using the following formula: X(n) = [x(n), x(n-1), x(n-2), ..., x(nJ)] T ;

[0076] where J is the filter order.

[0077] The coefficient vector consisting of the weights of the RLS adaptive filter is calculated by the following formula: W(n)=[w0(n),w1(n),...,w J (n)] T ;

[0078] The estimated output signal at the nth moment is then calculated using the following formula. In this embodiment, the estimated output signal is defined as d(n):

[0079] Finally, the RLS error signal w(n) is obtained by the following formula: ω(n)=p(n)-d(n)=p(n)-W T (n)X(n);

[0080] In some embodiments, the method further includes: generating an autocorrelation matrix of the input signal; calculating an inverse matrix of the autocorrelation matrix; and recursively calculating the inverse matrix to obtain coefficient update equations of the RLS adaptive filter at the first moment and the next moment after the first moment.

[0081] The autocorrelation matrix R of the input signal is calculated by the following formula D (n):

[0082] Among them, λ is the parameter forgetting factor of the least squares method, and the range of λ is 0-1.

[0083] Due to λ n-i , in the accumulation process, the earlier the data is, the better the autocorrelation matrix R D The smaller the impact of (n).

[0084] Then calculate the autocorrelation matrix R by the following formula D The inverse matrix of (n):

[0085] After further simplification, the coefficient update equation of the RLS adaptive filter is obtained: W(n)=W(n-1)+ω(n)R D (n) -1 X(n);

[0086] In some embodiments, the method further includes: performing iterative updates on the second vector using a coefficient update equation to obtain updated data; correcting the estimated output signal at the second moment using a recursive algorithm based on the updated data to obtain parameter estimates and a corrected estimated output signal, wherein the second moment is earlier than the first moment; calculating an estimated error using the estimated output signal and the corrected estimated output signal; and storing the second vector at the first moment if the estimated error is within an error threshold.

[0087] Exemplarily, the coefficient vector W(n) is iteratively updated using the RLS coefficient update equation. Each time new data is obtained, the previously estimated output signal d(n) is corrected using the newly introduced data according to a recursive algorithm to reduce the estimation error, thereby recursively deriving new parameter estimates until the estimation error is less than the required measurement accuracy. The coefficient vector at this time is stored and the coefficient vector at this moment is defined as the optimal coefficient vector.

[0088] S300: Establish an inversion measurement group through a transfer relationship.

[0089] S310: Establish an RLS training group based on the transmission relationship between the input signal and the output signal at different frequencies.

[0090] Among them, it is necessary to learn the input and output signals at different frequencies through the RLS adaptive algorithm to obtain the transfer relationship.

[0091] S320: Establish an inversion measurement group through the RLS training group, where the inversion measurement group includes parameter estimation values ​​at different frequencies.

[0092] 6 , the process of S200 is performed for each test frequency, and an inversion measurement group is established, wherein the inversion measurement group includes multiple RLS training groups, and different parameter estimation values ​​are obtained through the RLS training groups.

[0093] S400: Using the inversion measurement group, perform frequency division inversion on the output signal to be inverted to obtain a corrected transient current signal.

[0094] In some embodiments, the method further includes: receiving a measurement signal output by a current transformer; filtering out a distorted signal in the measurement signal; dividing the distorted signal using a short-time Fourier transform to obtain signals of different frequencies; inputting the signals of different frequencies into an inversion measurement group; obtaining estimated output signals of different frequencies based on the estimated values ​​of the parameters at different frequencies; and summing the estimated output signals of different frequencies to obtain a corrected transient current signal.

[0095] For example, referring to Figures 7 and 8, a signal inversion unit is connected in series to the output end of the current transformer, and the inversion test group is stored in the signal inversion unit. After the inversion signal unit receives the measurement signal output by the current transformer, it uses short-time Fourier transform to divide the frequency of the distorted signal, and then inputs the signals of different frequencies into the inversion test group accordingly. It is estimated that the set of output signals will be re-accumulated and restored to the corrected transient current signal, that is, signal reconstruction is performed. The corrected transient current signal is used as the output signal of the signal inversion unit and is used for the secondary equipment of the power system.

[0096] The expression of the signal after frequency division by Short-Time Fourier Transform (STFT) and its frequency is:

[0097] Where w′ is the signal that needs to be input into the signal inversion unit after frequency division, f is the frequency of the decomposed signal, and h(τ) is the time window, which takes the power frequency cycle as 20ms.

[0098] Referring to Figure 9 , unlike grid voltage measurement, transient current can significantly increase when a power system fault occurs, temporarily exceeding the transformer's range. While electromagnetic transformers allow for short-term overcurrent measurement and output, the signal inversion unit is limited by the sampling voltage of the analog-to-digital converter (ADC) chip, resulting in a limited measurement signal amplitude. This can cause clipping and distortion of the output signal to be inverted, leading to inversion failure. When a microprocessor measures analog signals, the analog current or voltage signal must be uniformly converted to a voltage signal and input into the ADC before it can be captured by the microcontroller. This process can lead to voltage clipping. Therefore, in some embodiments, the method further includes: detecting the amplitude of the corrected transient current signal; if the signal output amplitude is equal to a preset range, switching the gain using an automatic variable range algorithm to expand the range; measuring the measurement signal output by the current transformer; converting the measurement signal to a voltage signal; and restoring the range to the preset range if the voltage signal amplitude is less than a preset ratio of the maximum output voltage value.

[0099] In some embodiments, the method further comprises:

[0100] Whether the detection range is an extended range or a preset range;

[0101] If the measuring range is the extended range, a high-level signal is output, which is defined as a temporary modification ratio.

[0102] If the range is the preset range, a low-level signal is output. The low-level signal is defined as restoring the transformation ratio to the initial value.

[0103] Referring to Figures 10 and 11, an adaptive variable range module is added to the signal inversion unit as an example. As can be seen from the above, the corrected transient current signal is used as the output signal of the signal inversion unit. After detecting that the output signal is equal to the preset range, the gain is automatically switched to 20%, the range is expanded to 5 times, and a high-level switching output signal is sent to the microprocessor MCU to indicate that the ratio is temporarily modified, thereby measuring the over-range current. When the adaptive variable range module detects that the amplitude of the output signal measured by the signal inversion unit is less than 20% of the maximum voltage, the range is restored to 1 times, and a low-level switching output signal is sent to the microprocessor MCU to indicate that the ratio is restored to the preset value. For current signals, the adaptive variable range module, based on the improvement of the measurement accuracy of transient signals, widens the range of the invertible signal and enhances the frequency division inversion capability of transient large currents.

[0104] Referring again to Figure 11, the adaptive variable range module includes an absolute value circuit U1, a hysteresis comparator U2, and a programmable gain amplifier U3. Absolute value circuit U1 is connected to the current input port and is used to convert positive and negative bipolar signals into unipolar signals. Hysteresis comparator U2 is used to detect the preset range state and control the over-range indicator port. When the input port amplitude reaches the preset range voltage, it outputs a high level; when the input port amplitude drops below 20%, it outputs a low level. Programmable gain amplifier U3 controls the gain. When the input signal is low, the gain is 1x; when the input signal is high, the gain is controlled to 0.2x, thereby reducing the input port signal and expanding the range. Op amps TLV9151 and TLV2371 are available for U1 and U2, while the LTC6910 programmable gain amplifier chip is available for U3.

[0105] This embodiment provides an RLS adaptive transient current signal frequency division inversion measurement method. By incorporating an adaptive variable range module, the method can match the signal output characteristics with the transformer operating characteristics. Furthermore, the method eliminates the need to solve the inversion model using the current transformer transfer function, thereby reducing the impact of transfer function inaccuracies on the response results and effectively improving the accuracy and reliability of transient current signal detection. This embodiment utilizes the RLS algorithm for adaptive training, resulting in rapid convergence, high estimation accuracy, and excellent stability when extracting input and output signals. This method can suppress the convergence process of vibration acceleration, exhibits strong adaptability to non-stationary signals, and improves the inversion efficiency of transient current signals.

[0106] The present application provides an RLS adaptive transient current signal frequency division inversion measurement method, which includes: first obtaining a full-band measurement characteristic curve of a current transformer; then injecting a test signal into the current transformer according to the full-band measurement characteristic curve, and measuring the output signal of the current transformer; using an RLS adaptive algorithm to train the input signal and the output signal to obtain a transfer relationship between the input signal and the output signal; then establishing an inversion measurement group based on the transfer relationship; using the inversion measurement group to perform frequency division inversion on the output signal to be inverted to obtain a corrected transient current signal, and by dividing the frequency of the transformer output signal and inverting signals of different frequencies with the inversion measurement group, the problem of being unable to accurately obtain the transient current signal is resolved.

[0107] The above-described embodiments of the present application do not constitute a limitation on the scope of protection of the present application.

Claims

1. A RLS adaptive transient current signal frequency division inversion measurement method, characterized in that: include: Obtain the full-band measurement characteristic curve of the current transformer; Injecting a test signal into the current transformer according to the full-band measurement characteristic curve, and measuring an output signal of the current transformer; Using an RLS adaptive algorithm to train the input signal and the output signal to obtain a transfer relationship between the input signal and the output signal; Establishing an inversion measurement group through the transfer relationship; The inversion measurement group is used to perform frequency division inversion on the output signal to be inverted to obtain a modified transient current signal.

2. The RLS adaptive transient current signal frequency division inversion measurement method according to claim 1 is characterized in that: The test signal is an alternating current signal of different frequencies; the method further comprises: Generate multiple samples with the current transformer input signal and output signal at different frequencies, each sample corresponds to an RLS adaptive filter, and the sample includes the output signal to be inverted and the input signal as the desired signal; A plurality of the samples are input into an RLS adaptive filter to calculate an estimated output signal, and the estimated output signal is used to calculate an RLS error signal.

3. The RLS adaptive transient current signal frequency division inversion measurement method according to claim 2 is characterized in that: The method further comprises: Inputting the output signal and the input signal at a first frequency into the RLS adaptive filter; Calculate a vector composed of the input signal at the first moment as the first vector; calculate a coefficient vector composed of the RLS adaptive filter weights at the first moment as the second vector; Calculate an estimated output signal at a first moment using the first vector and the second vector; The difference between the estimated output signal and the input signal as the desired signal is calculated to obtain an RLS error signal.

4. The RLS adaptive transient current signal frequency division inversion measurement method according to claim 3 is characterized in that: The method further comprises: generating an autocorrelation matrix of the input signal; Calculating the inverse matrix of the autocorrelation matrix; The inverse matrix is ​​recursively derived to obtain coefficient update equations of the RLS adaptive filter at a first moment and at a moment next to the first moment.

5. The RLS adaptive transient current signal frequency division inversion measurement method according to claim 4 is characterized in that: The method further comprises: Iteratively updating the second vector using the coefficient update equation to obtain update data; According to the update data, using a recursive algorithm to correct the estimated output signal at a second moment to obtain a parameter estimation value and a corrected estimated output signal, the second moment being earlier than the first moment; Calculating an estimation error using the estimated output signal and the corrected estimated output signal; If the estimated error is within an error threshold, the second vector at the first moment is stored.

6. The RLS adaptive transient current signal frequency division inversion measurement method according to claim 5, characterized in that: The inversion measurement group is established through the transfer relationship, which also includes: Establishing an RLS training group through a transfer relationship between the input signal and the output signal at different frequencies; An inversion measurement set is established through the RLS training set, wherein the inversion measurement set includes the parameter estimation values ​​at different frequencies.

7. The RLS adaptive transient current signal frequency division inversion measurement method according to claim 6, characterized in that: The method further comprises: Receiving a measurement signal output by the current transformer; Screening out distorted signals in the measurement signal; Using short-time Fourier transform to divide the frequency of the distorted signal to obtain signals of different frequencies; Inputting the signals of different frequencies into the inversion measurement group; Obtaining the estimated output signals at different frequencies according to the estimated parameter values ​​at different frequencies; The estimated output signals of different frequencies are summed to obtain a modified transient current signal.

8. The RLS adaptive transient current signal frequency division inversion measurement method according to claim 1, characterized in that: The method further comprises: Detecting the corrected transient current signal amplitude; If the signal output amplitude is equal to the preset range, the gain is switched using an automatic variable range algorithm to expand the range.

9. The RLS adaptive transient current signal frequency division inversion measurement method according to claim 8, characterized in that: The method further comprises: measuring a measurement signal output by the current transformer; Converting the measurement signal into a voltage signal; If the voltage signal amplitude is less than the maximum output voltage value of the preset ratio, the range is restored to the preset range.

10. The RLS adaptive transient current signal frequency division inversion measurement method according to claim 9, characterized in that: The method further comprises: detecting whether the measuring range is an extended measuring range or a preset measuring range; If the measuring range is the extended measuring range, a high level signal is output, and the high level signal is defined as a temporary modification ratio; If the measuring range is a preset measuring range, a low level signal is output, and the low level signal is defined as restoring the transformation ratio to an initial value.

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