A metrology chip calibration method

Abstract

The application provides a new metering chip calibration method, which comprises the following steps: setting a platform body, i.e., an electric energy meter testing device, to output under the condition of a power factor of 1.0, obtaining data of the output of the platform body, and data P of the output of the platform body after metering by a metering chip 功率原始值 ; calculating a voltage proportional coefficient R 电压 , a current proportional coefficient R 电流 and a power proportional coefficient R 1.0功率 ; setting the platform body to output under a preset power factor condition, calculating a power error Err 功率 under the current condition, calculating an angle difference β and sine and cosine values of the angle difference β; judging whether to perform secondary compensation calibration; calculating a power proportional coefficient R 1.0功率 under the current power factor condition according to the power proportional coefficient R 功率 , the angle difference β and the sine and cosine values of the angle difference β, so as to calculate an accurate power effective value P 功率有效值 ; and completing the metering chip calibration. The application further provides a metering chip calibration device.

Description

Technical Field

[0001] This invention relates to a calibration method, and more particularly to a calibration method for a metrology chip. Background Technology

[0002] Currently, the traditional calibration method in the industry involves the main control chip calculating the calibration value based on the output of the calibration platform and then writing it to the metrology chip. After the metrology chip completes the calibration, it outputs accurate metrological data. This method requires rewriting the calibration parameters into the metrology chip every time it is initialized, which lengthens the initialization process. If a short interval between power-on and pulse output is required, then shortening the initialization time of the metrology chip is particularly important.

[0003] Due to hardware limitations, the data collected by the metering chip is not entirely accurate and requires calibration. Currently, there are two main calibration methods: multi-point calibration and single-point calibration. However, both methods require writing calibration parameters into the metering chip's registers during the initialization phase.

[0004] The calibration parameters of the metering chip mainly include three types: ratio difference, angle difference, and small signal compensation.

[0005] The multi-point calibration method first calibrates the ratio difference when the power factor is 1.0. Then, it calibrates the angle difference after switching the power factor of the platform to 0.5L. Finally, it switches back to a power factor of 1.0 and defines a small-signal compensation point according to the current specifications of the metering instrument, such as 5% of the rated current, and performs small-signal compensation as needed.

[0006] The single-point calibration method first calibrates the angle difference when the power factor is 0.5L. This requires that the accurate angle difference compensation parameters can be calculated from the measurement data output by the metering chip in its initial state. After calibrating the angle difference, the measurement data after angle difference calibration is read again, and the difference is compared for recalibration. The method for small signal compensation is the same as the multi-point calibration method.

[0007] In a discrete design, where the main control chip and the metrology chip are not packaged on a single chip, they need to exchange data through a hardware communication interface. Because of the calibration parameters, the metrology chip must provide a receiving channel to receive the calibration parameters stored by the main control chip. This not only increases the initialization time of the metrology chip but also increases its design cost.

[0008] Due to hardware limitations, the calibration range of angular difference for metering chips is also greatly limited, generally only a few degrees positive or negative. Summary of the Invention

[0009] Purpose of the invention: The technical problem to be solved by the present invention is to provide a new calibration method for metrology chips, which addresses the shortcomings of the existing technology.

[0010] To address the aforementioned technical problems, this invention discloses a novel calibration method for a metrology chip, comprising the following steps:

[0011] Step 1: Set up the testing device (electricity meter) to output power under a power factor of 1.0, and acquire the output data from the device, as well as the data P after the output is measured by the metering chip. 功率原始值 ;

[0012] Step 2: Calculate the voltage proportionality coefficient R based on the data obtained in Step 1. 电压 Current proportionality coefficient R 电流 and power proportionality coefficient R 1.0功率 ;

[0013] Step 3: Configure the platform to output power under a preset power factor condition, and calculate the power error Err under the current conditions based on the platform's output data and the data measured by the metering chip. 功率 The angle difference β and its sine and cosine values ​​are calculated based on the power error.

[0014] Step 4: Determine whether to perform secondary compensation calibration; if secondary compensation calibration is required, determine the small signal point according to the specifications of the metering chip, calculate the error at the small signal point (i.e., the small signal error), and perform secondary compensation based on the small signal error; otherwise, proceed to step 5.

[0015] Step 5, according to the power ratio coefficient R mentioned in Step 1 1.0功率 Using the angle difference β and its sine and cosine values, the power ratio coefficient R under the current power factor condition is calculated. 功率 Thus, the accurate effective power value P can be calculated. 功率有效值 ;

[0016] Step 6: Complete the calibration of the metering chip.

[0017] The platform output data mentioned in step 1 of this invention includes: the platform output power, the platform output rated voltage, and the platform output rated current.

[0018] The output data of the platform after being measured by the metering chip includes: the power measured by the metering chip, the voltage measured by the metering chip, and the current measured by the metering chip.

[0019] The power proportionality coefficient R mentioned in step 2 of this invention 1.0功率 The calculation methods include:

[0020] R 1.0功率 = Power measured by the metering chip / Power output by the platform.

[0021] The preset power factor mentioned in step 3 of this invention is any value other than 1.0 mentioned in step 1.

[0022] The data output by the platform in step 3 includes: the voltage-current angle α of the platform output under the preset power factor condition, and the output power of the platform under the preset power factor condition, denoted as P. 非1.0 .

[0023] The output data of the platform after being measured by the metering chip includes: the output power obtained by the metering chip under a preset power factor condition, denoted as P. 计 .

[0024] The power error Err mentioned in step 3 功率 The calculation method is as follows:

[0025] Err 功率 = (P 计 - P 非1.0 ) / P 非1.0 .

[0026] The method for calculating the angle difference β described in step 3 is as follows:

[0027] tanβ= (Err 功率非1.0 + 1) / tanα

[0028] Wherein, α is the voltage-current angle between the output voltage of the platform under the preset power factor condition described in step 3; when using a computer program for calculation, the following method is adopted:

[0029] sin²β= Err 功率非1.0 ² / (Err 功率非1.0 ² + tan²α)

[0030] The direction of the voltage-current angle difference β passes through Err. 非1.0 If Err 非1.0 If the value is negative, then β is a negative angle, and sinβ is a negative number; otherwise, β is positive.

[0031] The active power ratio coefficient R obtained in step 4 is the preset power factor condition. 功率 The method is as follows:

[0032] R 功率 = (cos(α+β) / (cosα * cosβ)) * R 1.0功率

[0033] Among them, R 1.0功率 The power proportionality coefficient R mentioned in step 1 1.0功率 .

[0034] The method for performing secondary compensation calibration as described in step 5 includes:

[0035] P 功率offset = P S台体 * cosα- P S * cos(α+β) / R 功率

[0036] Among them, P 功率offset It is the power deviation at the small signal point, P S It is the raw apparent power value within the metering chip, i.e., the power obtained after being measured by the metering chip, P S台体 It is the apparent power RMS value of the platform output, that is, the power output by the platform.

[0037] The method for completing the calibration of the metering chip in step 6 includes:

[0038] Current effective value = Original value / Scale factor R + Secondary compensation value, that is:

[0039] P 功率有效值 = P 功率原始值 / R 功率 + P 功率offset .

[0040] Beneficial effects:

[0041] 1. This invention proposes a calibration circuit that can operate independently of a metrology chip. Real-time calibration can be completed using only the raw data from the metrology chip.

[0042] 2. This invention enables a calibration register that is completely independent of the metering chip, and adjusts the proportional coefficient in real time to achieve the purpose of calibration.

[0043] 3. The metering chip calibration method proposed in this invention eliminates the limitation on the angle difference calibration range. Attached Figure Description

[0044] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0045] Figure 1 This is a schematic diagram of the calibration process in this invention.

[0046] Figure 2 This is a schematic diagram of the calculation process for each power effective value. Detailed Implementation

[0047] like Figure 1 As shown, this invention proposes a novel calibration method for a metrology chip, comprising the following steps:

[0048] Step 1: Set up the testing device (electricity meter) to output power under a power factor of 1.0, and acquire the output data from the device, as well as the data P after the output is measured by the metering chip. 功率原始值 ;

[0049] The output data of the platform includes: the output power of the platform, the rated output voltage of the platform, and the rated output current of the platform.

[0050] The output data of the platform after being measured by the metering chip includes: the power measured by the metering chip, the voltage measured by the metering chip, and the current measured by the metering chip.

[0051] Step 2: Calculate the voltage proportionality coefficient R based on the data obtained in Step 1. 电压 Current proportionality coefficient R 电流 and power proportionality coefficient R 1.0功率 ;

[0052] The power proportionality coefficient R 1.0功率 The calculation methods include:

[0053] R 1.0功率 = Power measured by the metering chip / Power output by the platform.

[0054] Step 3: Configure the platform to output power under a preset power factor condition, and calculate the power error Err under the current conditions based on the platform's output data and the data measured by the metering chip. 功率 The angle difference β and its sine and cosine values ​​are calculated based on the power error.

[0055] The preset power factor is any value other than 1.0 mentioned in step 1.

[0056] The data output by the platform includes: the voltage-current angle α of the platform output under a preset power factor condition, and the output power of the platform under the preset power factor condition, denoted as P. 非1.0 .

[0057] The output data of the platform after being measured by the metering chip includes: the output power obtained by the metering chip under a preset power factor condition, denoted as P. 计 .

[0058] The power error Err 功率The calculation method is as follows:

[0059] Err 功率 = (P 计 - P 非1.0 ) / P 非1.0 .

[0060] The method for calculating the angle difference β is as follows:

[0061] tanβ= (Err 功率非1.0 + 1) / tanα

[0062] Wherein, α is the voltage-current angle between the output voltage of the platform under the preset power factor condition described in step 3; when using a computer program for calculation, the following method is adopted:

[0063] sin²β= Err 功率非1.0 ² / (Err 功率非1.0 ² + tan²α)

[0064] The direction of the voltage-current angle difference β passes through Err. 非1.0 If Err 非1.0 If the value is negative, then β is a negative angle, and sinβ is a negative number; otherwise, β is positive.

[0065] Step 4: Determine whether to perform secondary compensation calibration; if secondary compensation calibration is required, determine the small signal point according to the specifications of the metering chip, calculate the error at the small signal point (i.e., the small signal error), and perform secondary compensation based on the small signal error; otherwise, proceed to step 5.

[0066] The calculation yields the active power ratio coefficient R under the preset power factor condition. 功率 The method is as follows:

[0067] R 功率 = (cos(α+β) / (cosα * cosβ)) * R 1.0功率

[0068] Among them, R 1.0功率 The power proportionality coefficient R mentioned in step 1 1.0功率 .

[0069] Step 5, according to the power ratio coefficient R mentioned in Step 1 1.0功率 Using the angle difference β and its sine and cosine values, the power ratio coefficient R under the current power factor condition is calculated. 功率 Thus, the accurate effective power value P can be calculated. 功率有效值 ;

[0070] The method for performing secondary compensation calibration includes:

[0071] P 功率offset = P S台体 * cosα- P S * cos(α+β) / R 功率

[0072] Among them, P 功率offset It is the power deviation at the small signal point, P S It is the raw apparent power value within the metering chip, i.e., the power obtained after being measured by the metering chip, P S台体 It is the apparent power RMS value of the platform output, that is, the power output by the platform.

[0073] Step 6: Complete the calibration of the metering chip.

[0074] The method for calibrating the metering chip as described herein includes:

[0075] Current effective value = Original value / Scale factor R + Secondary compensation value, that is:

[0076] P 功率有效值 = P 功率原始值 / R 功率 + P 功率offset .

[0077] Example:

[0078] like Figure 2 As shown, the measurement data read from the metering chip is generally the raw value, which has a proportional relationship with the actual value required. For example, when the voltage is 220V and the current is 5A, the raw voltage and current values ​​read from the metering chip are ADC conversion values, such as the raw voltage value being 110000 and the raw current value being 60000. Converting this to the actual voltage of 220V and current of 5A requires a scaling factor. Assuming the voltage is accurate to two decimal places and the current is accurate to three decimal places, then the voltage scaling factor R... U that is:

[0079] R U = 22000 / 110000 = 0.2

[0080] Similarly, the current proportionality coefficient R can be obtained. I yes:

[0081] R I = 5000 / 60000 = 0.83

[0082] The formula for obtaining the proportionality constant R is:

[0083] R = Current valid value / Original value; --------Formula 1

[0084] The proportionality coefficient R of active power can be obtained from Formula 1. P for:

[0085] R P = P S * cos(α+β) / P S台体 * cosα ----------Formula 2

[0086] Among them, P S It is the raw apparent power value within the metering chip, P S台体 It is the apparent power RMS value output by the test platform (three-phase / single-phase energy meter testing device), α is the voltage-current angle of the current output of the test platform, and β is the angle difference of the current output of the test platform.

[0087] Therefore, according to Formula 2, we can obtain:

[0088] R P1.0 = P S * cosβ / P S台体 ----------Formula 3

[0089] R P非1.0 = P S * cos(α+β) / P S台体 * cosα ----------Formula 4

[0090] R Q1.0 = P S * sinβ / P S台体 ----------Formula 5

[0091] R Q非1.0 = P S * sin(α+β) / P S台体 * sinα ----------Formula 6

[0092] Among them, R P1.0 R represents the active power proportionality coefficient when the power factor is 1.0. P非1.0 R represents the active power proportionality coefficient when the power factor is not 1.0. Q1.0 R represents the reactive power proportionality coefficient when the power factor is 1.0. Q非1.0 Represents the reactive power proportionality coefficient when the power factor is not 1.0;

[0093] From formulas 3 and 4, we can obtain:

[0094] R P非1.0= (cos(α+β) / (cosα * cosβ)) * R P1.0 ----------Formula 7

[0095] R S非1.0 = cosβ * R P1.0 ----------Formula 8

[0096] Among them, R S非1.0 The apparent power proportionality coefficient when the power factor is not 1.0;

[0097] From formulas 5 and 6, we can obtain:

[0098] R Q非1.0 = (sin(α+β) / (sinα * cosβ)) * R Q1.0 ----------Formula 9

[0099] Formulas 7 and 9 show that if the power proportionality coefficient and angle difference β can be calculated at a power factor of 1.0, the proportionality coefficient at any current power factor can be obtained, thus allowing for the calculation of an accurate effective power value.

[0100] The following is an explanation of the calibration process and principles, using active power as an example:

[0101] 1. The platform outputs active power under a power factor of 1.0, rated voltage Un, and rated current Ib. The voltage proportionality coefficient R is calculated using formula 1. U Current proportionality coefficient R I and R P1.0 ;

[0102] 2. Under the conditions of a power factor of 0.5L (0.5 inductance), rated voltage Un, and rated current Ib, the platform outputs active power. At this point, the voltage-current angle α is 60°. Calculate the current active power error Err. P0.5L The method is as follows:

[0103] Err P0.5L = (P S * cos(α+β) / R P1.0 - P S台体 * cosα) / P S台体 * cosα -- Formula 10

[0104] Formula 3 provides the following:

[0105] P S = P S台体 * R P1.0 / cosβ -------Formula 11

[0106] Substituting formula 11 into formula 10 yields:

[0107] Err P0.5L = (cos(α+β) / cosβ - cosα) / cosα

[0108] Err P0.5L = cos(α+β) / (cosα * cosβ) - 1

[0109] Err P0.5L + 1 = cos(α+β) / (cosα * cosβ)

[0110] Err P0.5L + 1 = tanα * tanβ

[0111] tanβ = (Err P0.5L + 1) / tanα ------- Formula 12

[0112] Among them, Err P0.5L Given that α is known, tanβ can be calculated. Since C only uses sine and cosine, it can be obtained using sin²γ + cos²γ = 1.

[0113] sin²β = Err P0.5L ² / (Err P0.5L 2 + tan²α) ------Formula 13

[0114] Taking the square root of Equation 13 yields sinβ, and the direction of the angle difference can be determined by Err. P0.5L If Err P0.5L If the value is negative, it means that α + β < α, so β ​​is a negative angle and sinβ is a negative number; otherwise, β is positive.

[0115] 3. Determine the small signal point according to the specifications of the actual instrument (generally according to the definition in standard documents, such as the State Grid standard, refer to "Q / GDW 10364—2020 Technical Specifications for Single-Phase Smart Energy Meters");

[0116] Referring to the definitions of minimum current and transition current in "Q / GDW 10364—2020 Technical Specification for Single-Phase Smart Energy Meters", the minimum current is defined as "the minimum current value that meets the accuracy class requirements of the energy meter", and the transition current is defined as "the maximum permissible error corresponding to the accuracy class of the energy meter within the minimum limit when the specified current value is greater than or equal to this value". The relationship between the two satisfies: transition current = 0.1 * rated current, minimum current = 0.5 * transition current. Therefore, the small-signal calibration point can be defined at the minimum current, which is 0.05 * rated current.

[0117] Taking the 5%Ib point as an example, the platform outputs active power at power factors of 1.0, Un, and 5%Ib. Calculate the current active power deviation P. offset The method is as follows:

[0118] P offset = P S台体 * cosα- P S * cos(α+β) / R P非1.0 --------Formula 14

[0119] Similarly, the reactive power deviation Q can be derived. offset

[0120] Q offset = P S台体 * sinα - P S * sin(α+β) / R Q非1.0 --------Formula 15

[0121] The secondary compensation value is not a mandatory calibration step; if the small-signal error of the hardware meets the standard requirements, this step can be omitted. The secondary compensation value is a vertical shift of the curve in Formula 1, therefore it does not affect the calculation of the proportional coefficient and angle difference.

[0122] Therefore, the final calibration formula is:

[0123] Current effective value = Original value / Scale factor R + Secondary compensation value -------- Formula 16

[0124] This completes the entire calibration process. After calibration, the calibration parameter voltage proportionality coefficient R is obtained. U Current proportionality coefficient R I R P1.0 R Q1.0 sinβ, cosβ, β, P offset Q offsetOnce the voltage-current angle α+β is obtained from the original values ​​of the current active and reactive power, the correct voltage-current angle α can be deduced from the angle difference β, thus obtaining the proportionality coefficient R. P非1.0 That is, the proportionality coefficient R in Formula 16, and the accurate effective values ​​of voltage, current and power are calculated according to Formula 16.

[0125] After calibration, the following parameters are obtained. Among them, the parameters related to small-signal secondary compensation are not mandatory. If the deviation under small signal is within the allowable range, calibration is not required:

[0126] 1) Active power proportionality coefficient;

[0127] 2) Reactive power ratio coefficient;

[0128] 3) Voltage proportionality coefficient;

[0129] 4) Current proportionality coefficient;

[0130] 5) Angular difference;

[0131] 6) Sine of the angle difference;

[0132] 7) Angle difference cosine;

[0133] 8) Voltage secondary compensation value;

[0134] 9) Current secondary compensation value;

[0135] 10) Active power secondary compensation value;

[0136] 11) Secondary reactive power compensation value;

[0137] 12) Apparent power secondary compensation value;

[0138] According to Formula 7, if we want to find R... P非1.0 This requires calculating the voltage-current angle α output by the current platform. This is because the voltage-current angle during metering chip conversion is α + β, and...

[0139] cos(α+β) = Original value of active power / Original value of apparent power ----------- Formula 14

[0140] Therefore, the voltage-current angle α+β can be calculated using the inverse cosine function in the C language's math library or the CMSIS DSP library. Since the cosine is positive in the first and fourth quadrants and negative in the second and third quadrants, it's necessary to determine the quadrant by judging the signs of the original active and reactive power values ​​to obtain the sign of α+β. After obtaining the correct α+β, since β has already been obtained through table calibration, α can then be calculated. Finally, R can be calculated in real-time using formula 7. P非1.0 Similarly, because

[0141] sin(α+β) = Original value of reactive power / Original value of apparent power ----------- Formula 15

[0142] R can be obtained by combining formulas 15 and 9. Q非1.0 Because the apparent power proportionality coefficient is independent of the current voltage-current angle, the active power proportionality coefficient R can now be obtained. P非1.0 Reactive power proportionality coefficient R Q非1.0 The proportionality coefficient R of apparent power S非1.0 .

[0143] At this point, the proportional coefficients of active power, reactive power, and apparent power under all power factors can be obtained. The effective value of each power can be calculated by following Formula 1.

[0144] In its specific implementation, this application provides a computer storage medium and a corresponding data processing unit. The computer storage medium is capable of storing a computer program, which, when executed by the data processing unit, can run the invention's content regarding a novel metrology chip calibration method and some or all of the steps in various embodiments. The storage medium can be a magnetic disk, optical disk, read-only memory (ROM), or random access memory (RAM), etc.

[0145] Those skilled in the art will clearly understand that the technical solutions in the embodiments of the present invention can be implemented using computer programs and their corresponding general-purpose hardware platforms. Based on this understanding, the technical solutions in the embodiments of the present invention, or the parts that contribute to the prior art, can be embodied in the form of computer programs, i.e., software products. These computer program software products can be stored in a storage medium and include several instructions to cause a device containing a data processing unit (which may be a personal computer, server, microcontroller, MUU, or network device, etc.) to execute the methods described in various embodiments or certain parts of the embodiments of the present invention.

[0146] This invention provides a novel approach and method for calibrating metrology chips. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A metrology chip calibration method, characterized by, The method comprises the following steps: Step 1, set the platform body, i.e. the electric energy meter inspection device, to carry out output under the condition of power factor 1.0, and obtain the data of the output of the platform body and the data P of the output of the platform body after metering by the metering chip 功率原始值 ; Step 2, according to the data obtained in step 1, the voltage ratio coefficient R is calculated 电压 , the current ratio coefficient R 电流 and the power ratio coefficient R 1.0功率 ; Step 3, set the table body to output under preset power factor condition, and calculate the power error Err under current condition according to the data output by the table body and the data output by the table body after metering by the metering chip 功率 and calculate the angle difference β and the sine and cosine values thereof according to the power error. Step 4: judging whether to perform secondary compensation calibration; if yes, determining a small signal point according to the specification of the metering chip, calculating the error at the small signal point, i.e. small signal error, and performing secondary compensation according to the small signal error; otherwise, entering step 5; Step 5, the power ratio factor R under the current power factor condition is calculated according to the power ratio factor R described in step 2 1.0功率 , the angle difference β and its sine and cosine values described in step 3 功率 , so as to calculate the accurate power effective value P 功率有效值 ; Step 6: completing the calibration of the metering chip; wherein the calculation in step 5 yields the power scaling factor R under the current power factor condition 功率 The method is as follows: R 功率 = (cos(α+β) / (cosα * cosβ)) * R 1.0功率 wherein R 1.0功率 is the power scaling factor R 1.0功率 described in step 1. The method for performing secondary compensation calibration comprises: P 功率offset = P S台体 * cosα- P S * cos(α+β) / R 功率 wherein a is the voltage-current angle of the output of the platform at the preset power factor condition described in step 3, P 功率offset is the power deviation at the small signal point, P S is the apparent power raw value in the metering chip, i.e., the power obtained by metering the metering chip, P S台体 is the apparent power effective value of the output of the platform, i.e., the power output by the platform; The method for completing the calibration of the metering chip in step 6 comprises: The current effective value = original value / proportionality coefficient R + secondary compensation value, i.e. P 功率有效值 = P 功率原始值 / R 功率 + P 功率offset 。 2. The method of claim 1, wherein the method further comprises: The data output by the power station in step 1 comprises: power output by the power station, rated voltage output by the power station and rated current output by the power station. The data output by the power station after metering by the metering chip comprises: power obtained after metering by the metering chip, voltage obtained after metering by the metering chip and current obtained after metering by the metering chip.

3. The method of claim 2, wherein the calibration of the metrology chip is performed by: The power ratio coefficient R described in step 2 1.0功率 The calculation method comprises: R 1.0功率 = power measured by the metrology chip / power of the power supply output.

4. The method of claim 3, wherein the calibration of the metrology chip is performed by: The preset power factor in step 3 is any value other than 1.0 in step 1.

5. The method of claim 4, wherein the calibration of the metrology chip is performed by: The data outputted by the platform body in step 3 includes: the voltage-current angle α of the platform body under the preset power factor condition, and the output power of the platform body under the preset power factor condition, denoted as P 非1.0 ; The output of the platform body after metering by the metering chip includes: output power obtained after metering by the metering chip under a preset power factor condition, denoted as P 计 .

6. The method of claim 5, wherein the calibration of the metrology chip is performed by: The power error Err described in step 3 功率 is calculated as follows: Err 功率 = (P 计 - P 非1.0 ) / P 非1.0 .

7. The method of claim 6, wherein the method further comprises: The method for calculating the angle difference β in step 3 is as follows: tan β = (Err 功率 + 1) / tan α Wherein, α is the voltage-current angle of the power station output under the preset power factor in step 3; when a computer program is used for calculation, the following method is adopted: When a computer program is used for calculation, the following method is adopted: sin²β = Err 功率 ² / (Err 功率 ² + tan²α) where the direction of the angle difference β is given by Err 功率 If Err 功率 is negative, then β is a negative angle and sin β is negative; otherwise β is positive.

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