Initial phase angle high-precision measuring method and measuring device based on double-point angle difference automatic correction

Abstract

The invention discloses an initial phase angle high-precision measurement method and device based on automatic correction of a double-point angle difference value, and relates to the technical field of electric signal measurement of relay protection devices. In order to overcome the defects that an existing electric signal angle calibration device is limited by sampling frequency, large in difference estimation error and incapable of achieving dynamic compensation, an initial phase angle and cyclic wave data are measured through electric signal break variables; calculating an angle difference value between the second point and the first point according to the cyclic wave data; calculating a reference angle according to the number of sampling points, and calculating a compensation reference quantity; a compensation coefficient model is adopted to obtain an angle dynamic compensation coefficient, and the initial phase angle is dynamically compensated according to the angle difference value; and calibrating a real-time phase angle difference value, and calibrating an initial phase angle according to the real-time phase angle difference value. The method is mainly used for compensating the break variable of the electric signal.

Description

Technical Field

[0001] The present invention relates to the technical field of electrical signal measurement of relay protection devices, and particularly to a high-precision measurement method and device for initial phase angle based on automatic correction of double-point angle difference. Background Art

[0002] For the voltage and current input into the relay protection device, when calculating the initial angle, the Fourier filtering algorithm is usually used to obtain the voltage and current vectors, and then the angle is obtained. However, when using this method, the error is usually large, and it is limited by the number of sampling points. For example, for 32-point sampling, the angle between the current sampling point and the next sampling point is 360 / 32 = 11.25 degrees. At this time, the error between the calculated result of the initial phase angle and the actual added quantity reaches 11.25 degrees. By increasing the number of sampling points, the error can only be slightly improved. And this is only the theoretical error at this time, without considering whether the initial point capture is accurate. If there are fluctuations in the starting stage, there will also be a certain error in the angle calculation and other problems, and these errors are all objective errors and cannot be avoided.

[0003] In the prior art, angle calibration is usually achieved through hardware synchronization or software interpolation, but limited by the sampling frequency, angle error is still difficult to avoid. Currently, there is an angle compensation method based on linear interpolation, which estimates the true angle through linear interpolation between adjacent sampling points. However, this method does not consider the non-linear characteristics of angle change, and the compensation amount is fixed and cannot be dynamically compensated, so the error is still relatively large.

[0004] Therefore, there is a need for a high-precision measurement method and device for initial phase angle based on automatic correction of double-point angle difference, which can dynamically compensate the sampling angle with high precision, have small error, high precision, and can dynamically compensate the phase angle difference. Summary of the Invention

[0005] The present invention is to solve the defects of the existing electrical signal angle calibration device, such as being limited by the sampling frequency, large difference estimation error, and inability to dynamically compensate. It provides a high-precision measurement method and device for initial phase angle based on automatic correction of double-point angle difference, which can dynamically compensate the sampling angle with high precision, have small error, high precision, and can dynamically compensate the phase angle difference.

[0006] The high-precision measurement method for initial phase angle based on automatic correction of double-point angle difference of the present invention includes the following steps: S1. Measure the initial phase angle and cycle data using the electrical signal mutation amount; S2. Calculate the angle difference between the second point and the first point according to the cycle data; S3. Calculate the reference angle according to the number of sampling points and calculate the compensation reference quantity ; S4. Preset a dynamic compensation coefficient to dynamically compensate the initial phase angle according to the angle difference ΔA; S5. Calibrate the real-time phase angle difference, and calibrate the initial phase angle according to the real-time phase angle difference.

[0007] Furthermore: The triggering condition for measuring the initial phase angle is that when the relay protection device detects a sudden change in voltage or current, the initial phase angle measurement function is automatically started.

[0008] Furthermore: The calculation process of the angle difference is as follows: The first point starts from the first point of the sudden change start, uses one-cycle data starting from the first point, and calculates the first point angle A1 based on the Fourier algorithm; calculates the second point angle A2 using one-cycle data starting from the second point, and then calculates the difference ∆A = A2 - A1.

[0009] Furthermore: The dynamic compensation of the initial phase angle according to the angle difference ΔA includes: When the angle difference ∆A is between 10.0 - 11.5 degrees, the initial phase angle A = A1 - 1.2 * ; When the angle difference ∆A is between 11.6 - 12.0 degrees, the initial phase angle A = A1 - 1.0 * ; When the angle difference ∆A is between 12.0 - 12.4 degrees, the initial phase angle A = A1 - 0.8 * ; When the angle difference ∆A is between 12.5 - 13.5 degrees, the initial phase angle A = A1 - 0.1 * ; When the angle difference ∆A is between 13.6 - 14.5 degrees, the initial phase angle A = A1; When the angle difference ∆A is between 14.5 - 15.9 degrees, the initial phase angle A = A1 + 0.5 * (∆A / A0) * ; When the angle difference ∆A is 16.0 degrees or more, the initial phase angle A = A1 + 0.8 * (∆A / A0) * ; where A0 is the reference angle.

[0010] Furthermore: The calculation steps of the real-time phase angle difference are as follows: Calculate the real-time phase angle of the current three-phase power; Calculate the real-time phase angle differences and the initial phase angle differences of the AB phase, BC phase, and CA phase, continue to find the differences between the real-time phase angle differences and the initial phase angle differences of the AB phase, BC phase, and CA phase, and find the smallest difference between the two phases; Calculate the difference between the real-time phase angle difference and the initial phase angle difference, and find the two phases with the smallest difference.

[0011] Further: The specific calibration initial phase angle includes: Calculate the real-time phase angle difference value, calculate the difference between the real-time phase angle difference value and the initial phase angle difference value, and find out the two phases with the smallest difference; take the two phases with the smallest difference as the reference phases, and correct the initial phase angle of the third phase according to the real-time phase angle difference value.

[0012] The measuring device for realizing the high-precision measurement method of the initial phase angle based on the automatic correction of the double-point angle difference according to the present invention includes a signal acquisition device, a dynamic compensation module and a difference correction module; The signal acquisition device is used to acquire the mutation amount and cycle data of the electric signal; The dynamic compensation module is used to dynamically compensate the angle difference of the electric signal; The difference correction module is used to correct the initial phase angle.

[0013] The beneficial effects of the present invention are: The present invention provides a calibration method based on double-point angle with compensation. By adopting this method, the angle error caused by the sampling point number limitation can be significantly reduced. Taking 32-point sampling as an example, the error is mostly below 2 degrees, and the maximum error is about 5 degrees. Based on the double-point angle difference, the present invention introduces a high-precision calibration mechanism for the real-time phase angle difference to further calibrate the initial phase angle; a high-precision compensation coefficient model for the sampling initial phase angle is used to dynamically compensate the initial sampling angle, and improve the calculation accuracy of the initial phase angle of the added device. It enables obtaining relatively accurate initial addition angles of current and voltage without changing the sampling rate, saves costs, and meets the on-site requirements.

[0014] The present invention introduces a high-precision calibration mechanism for the real-time phase angle difference. According to the three-phase phase angle difference calculated at the current moment, compare with the three-phase initial phase angle difference, take the two phases with the smallest difference as the reference phases, correct the calculated value of the initial phase angle of the other phase, further improve the accuracy, and reduce the situation where the error of a certain phase is too large. Description of the Drawings

[0015] Figure 1 It is a schematic flowchart of the high-precision measurement method of the initial phase angle based on the automatic correction of the double-point angle difference. Detailed Embodiments

[0016] The following are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention should be covered within the protection scope of the present invention. The following embodiments are only used to explain the present invention and cannot be construed as a limitation of the present invention. The protection scope of the present invention should be subject to the protection scope of the claims. The embodiments of the present invention are described in detail below. For the convenience of describing the present invention and simplifying the description, the technical terms used in the specification of the present invention should be interpreted in a broad sense, including but not limited to the conventional replacement schemes not mentioned in this application, and including both direct implementation methods and indirect implementation methods.

[0017] Embodiment 1 Combined with Figure 1 To illustrate this embodiment, the high-precision measurement method for the initial phase angle based on automatic correction of the double-point angle difference disclosed in this embodiment includes the following steps: S1. Measure the initial phase angle and cycle data using the sudden change amount of the electrical signal; Measure the initial phase angle; Adopt the sudden change amount to start the initial phase angle measurement method. When voltage and current are applied to the device, the initial phase angle measurement function is started; Trigger condition: When the relay protection device detects a sudden change amount of voltage or current, the initial phase angle measurement function is automatically started.

[0018] Data recording: Starting from the first point where the sudden change amount is triggered, record the data of one cycle (complete cycle) plus one sampling point. For example, for a 32-point sampling system, record 33 sampling points.

[0019] S2. Calculate the angle difference ΔA between the second point and the first point according to the cycle data; Data preparation and preliminary calculation; After the data preparation is completed, use the data of one cycle starting from the first point to calculate the first point angle A1 based on the Fourier algorithm; use the data of one cycle starting from the second point to calculate the second point angle A2, and then calculate the difference ∆A = A2 - A1; After starting, record the sampled one cycle + one point data starting from the first sudden change amount trigger point; Calculate the angle using the Fourier algorithm: Use the data of one cycle (32 points) starting from the first sampling point to calculate the initial phase angle A1.

[0020] Use the data of one cycle starting from the second sampling point to calculate the initial phase angle A2.

[0021] Calculate the angle difference: ΔA = A2 - A1.

[0022] S3. Calculate the reference angle according to the number of sampling points and calculate the compensation reference quantity ; Calculation of reference angle and compensation reference quantity; Calculate the reference angle A0 based on the number of sampling points; taking 32 points as an example, according to the number of sampling points 32, calculate the reference angle A0 = 360 / 32 = 11.25°, and the compensation reference quantity Acomp = 11.25 / 2 ≈ 5.6°. According to the Fourier series algorithm, the 32-point sampling data can be decomposed into the real part , imaginary part . In one coordinate axis, the actual phase of this cycle analog quantity can be obtained through the inverse trigonometric function algorithm from the real part and the imaginary part. The formulas after simplifying the real part and the imaginary part of the Fourier algorithm: ; ; Among them, N is the number of sampling points in one cycle, n is the multiple of the fundamental wave frequency (n = 1, 2, 3...). When using the 32-point full-cycle Fourier fundamental wave algorithm, take N = 32 and n = 1. k refers to the current k-th point, ranging from 0 to N - 1, a total of N points; is the sampling value of the k-th point.

[0023] S4. Preset the dynamic compensation coefficient, and dynamically compensate the initial phase angle according to the angle difference ΔA; According to experimental tests, summarize the angle dynamic compensation coefficient. Through a large number of experiments, many raw data are obtained, including the angle difference data between the second point and the first point, and the angle difference data between the applied analog quantity and the calculated value of the initial phase angle. By drawing data points on the table axis and fitting them in segments according to the degree of dispersion, an approximate compensation model and an approximate compensation coefficient are obtained.

[0024] Dynamically compensate according to the angle difference ΔA, and the dynamic compensation satisfies the following relationship: When the angle difference ∆A is between 10.0 - 11.5 degrees, the initial phase angle A = A1 - 1.2 * Acomp; When the angle difference ∆A is between 11.6 - 12.0 degrees, the initial phase angle A = A1 - 1.0 * Acomp; When the angle difference ∆A is between 12.0 - 12.4 degrees, the initial phase angle A = A1 - 0.8 * Acomp; When the angle difference ∆A is between 12.5 - 13.5 degrees, the initial phase angle A = A1 - 0.1 * Acomp; When the angle difference ∆A is between 13.6 - 14.5 degrees, the initial phase angle A = A1; When the angle difference ∆A is between 14.5 - 15.9 degrees, the initial phase angle A = A1 + 0.5 * (∆A / A0) * Acomp; When the angle difference ∆A is 16.0 degrees and above, the initial phase angle A = A1 + 0.8 * (∆A / A0) * Acomp.

[0025] S5. Calibrate the real-time phase angle difference and calibrate the initial phase angle according to the real-time phase angle difference.

[0026] Calculate the real-time phase angle difference: First, calculate the real-time phase angles of the current three-phase power quantities (phases A, B, and C); these phase angles are calculated in real time from the current sampling values, with almost no phase angle error.

[0027] Then, calculate the real-time phase angle differences and the initial phase angle differences of phases AB, BC, and CA. Continue to find the differences between the real-time phase angle differences and the initial phase angle differences of phases AB, BC, and CA, and find the smallest difference between two phases.

[0028] Finally, calculate the difference between the real-time phase angle difference and the initial phase angle difference, and find the two phases with the smallest difference; Calculate the initial phase angles of the first two points. According to the magnitude of the two-point angle difference, substitute it into the high-precision compensation model to dynamically compensate the calculated angle of the initial phase angle, and greatly correct the measurement error of the initial phase angle.

[0029] Compared with calculating the initial phase angle at a single point, the calculation accuracy is greatly improved; compared with the linear compensation of two-point calculation, the accuracy can also be further improved.

[0030] Calibrate the initial phase angle: Take the two phases with the smallest difference as the reference phases (such as phases A and B), and correct the initial phase angle of the third phase (such as phase C) according to the real-time phase angle difference. For example, if the difference between AB is the smallest, then use the initial phase angle of phase A or phase B as the reference to adjust the initial phase angle of phase C.

[0031] In this embodiment, based on the difference between the real-time phase angle difference and the initial phase angle difference of the two smallest phases, according to the angle of the real-time phase angle difference, the initial phase angle of another phase is obtained on the basis of the initial phase angle of the reference phase. For example, if the difference between AB is the smallest, then use the initial phase angle of phase A or phase B as the reference phase, and correct phase C according to the real-time phase angle difference. This method can correct the initial phase angle with a large error and obtain a more accurate measurement value of the initial phase angle.

[0032] Generalization extension: This calculation method of initial phase angle measurement is also applicable to systems with different sampling points, such as 40 points, 96 points, etc. And the higher the sampling rate, the better the actual effect and the higher the measurement accuracy of the initial phase angle.

[0033] Verification and output: Verify the accuracy of the compensation model through experimental tests to ensure that the error is within an acceptable range (for example, when sampling 32 points, the error is less than 2 degrees, and the maximum does not exceed 5.6 degrees), and output the final high-precision measurement value of the initial phase angle.

Claims

1. An initial phase angle high-precision measurement method based on automatic correction of the double-point angle difference, characterized in that It includes the following steps: S1. Measure the initial phase angle and cycle data using the sudden change amount of the electrical signal; S2. Calculate the angle difference ΔA between the second point and the first point according to the cycle data; S3. Calculate the reference angle based on the number of sampling points and calculate the compensation reference quantity ; S4. Preset a dynamic compensation coefficient, and dynamically compensate the initial phase angle according to the angle difference ΔA; S5. Calibrate the real-time phase angle difference, and calibrate the initial phase angle according to the real-time phase angle difference.

2. The high-precision measurement method for initial phase angle based on automatic correction of double-point angle difference according to claim 1, characterized in that The trigger condition for measuring the initial phase angle is that when the relay protection device detects a sudden change in voltage or current, the initial phase angle measurement function is automatically started.

3. The high-precision measurement method for initial phase angle based on automatic correction of double-point angle difference according to claim 1, characterized in that The calculation process of the angle difference is as follows: The first point starts from the first point when the sudden change amount starts. Use one cycle of data starting from the first point, and calculate the first point angle A1 based on the Fourier algorithm; calculate the second point angle A2 using one cycle of data starting from the second point, and then calculate the difference ∆A = A2 - A1.

4. The high-precision measurement method for initial phase angle based on automatic correction by double-point angle difference according to claim 1, characterized in that The dynamic compensation of the initial phase angle according to the angle difference ΔA includes: When the angular difference ΔA is between 10.0 and 11.5 degrees, the initial phase angle A = A1 - 1.2* ; When the angle difference ΔA is between 11.6 - 12.0 degrees, the initial phase angle A = A1 - 1.0* ; When the angle difference ΔA is between 12.0 - 12.4 degrees, the initial phase angle A = A1 - 0.8* ; When the angle difference ΔA is between 12.5 and 13.5 degrees, the initial phase angle A = A1 - 0.1* ; When the angle difference ΔA is between 13.6 - 14.5 degrees, the initial phase angle A = A1; When the angle difference ΔA is between 14.5 - 15.9 degrees, the initial phase angle A = A1 + 0.5*(∆A / A0)* ; When the angular difference ΔA is 16.0 degrees or more, the initial phase angle A = A1 + 0.8 * (∆A / A0) * ; Wherein, A0 is the reference angle.

5. The high-precision measurement method for initial phase angle based on automatic correction by double-point angle difference according to claim 1, characterized in that The calculation steps of the real-time phase angle difference are: Calculate the real-time phase angles of the current three-phase electrical quantities; Calculate the real-time phase angle differences of the AB phase, BC phase, CA phase and the initial phase angle difference, continue to calculate the differences between the real-time phase angle differences of the AB phase, BC phase, CA phase and the initial phase angle difference, and find the difference between the two smallest phases; Calculate the difference between the real-time phase angle difference and the initial phase angle difference, and find the two phases with the smallest difference.

6. The high-precision measurement method for the initial phase angle automatically corrected based on the double-point angle difference according to claim 1, characterized in that The calibration of the initial phase angle specifically includes: Calculate the real-time phase angle difference, calculate the difference between the real-time phase angle difference and the initial phase angle difference, and find the two phases with the smallest difference; use the two phases with the smallest difference as the reference phases, and correct the initial phase angle of the third phase according to the real-time phase angle difference.

7. A measuring device for implementing the high-precision measurement method of the initial phase angle with automatic correction based on the double-point angle difference according to any one of claims 1-6, characterized in that, It includes a signal acquisition device, a dynamic compensation module and a difference correction module; The signal acquisition device is used to acquire the sudden change amount of the electrical signal and the cycle data; The dynamic compensation module is used to dynamically compensate the angle difference of the electrical signal; The difference correction module is used to correct the initial phase angle.

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