CN114167135B - Voltage-current phase angle distinguishing method for power meter - Google Patents
Voltage-current phase angle distinguishing method for power meter Download PDFInfo
- Publication number
- CN114167135B CN114167135B CN202111399033.4A CN202111399033A CN114167135B CN 114167135 B CN114167135 B CN 114167135B CN 202111399033 A CN202111399033 A CN 202111399033A CN 114167135 B CN114167135 B CN 114167135B
- Authority
- CN
- China
- Prior art keywords
- current
- voltage
- cos
- phase
- alpha
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R25/00—Arrangements for measuring phase angle between a voltage and a current or between voltages or currents
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R21/00—Arrangements for measuring electric power or power factor
- G01R21/006—Measuring power factor
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R21/00—Arrangements for measuring electric power or power factor
- G01R21/133—Arrangements for measuring electric power or power factor by using digital technique
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Measurement Of Current Or Voltage (AREA)
- Measuring Phase Differences (AREA)
Abstract
The invention provides a voltage and current phase angle distinguishing method for a power meter, and relates to the technical field of electric parameter measurement. The voltage and current signals are subjected to software operation to obtain active power P, a voltage effective value U and a current effective value I, a power factor cos alpha is calculated according to cos alpha=P/(U.I), the current signals are phase-shifted by one sampling period, and a new power factor lambda is calculated New type Calculating an angle difference beta calculated by one sampling period relative to the frequency of the current sine wave signal to be measured, further calculating sin beta and cos beta, calculating sin alpha by using a trigonometric function and a difference angle formula, confirming the specific quadrant in which alpha is positioned, and confirming the unique alpha. Compared with the prior art, the phase-shifting method has the advantages that the phase shifting is carried out for one sampling period, the voltage and current phase angle judgment is carried out by combining the trigonometric function and the difference angle formula, the mode of identifying the phase by using a sine wave-to-square wave circuit is abandoned, an unnecessary circuit is omitted, the material cost is reduced, and meanwhile, the identification precision is improved.
Description
Technical Field
The invention relates to the technical field of electric parameter measurement, in particular to a voltage-current phase angle distinguishing method for a power meter.
Background
The power meter is widely applied as a basic instrument for measuring electric parameters, and can simultaneously measure a plurality of electric parameters such as voltage effective values, current effective values, power factors and the like, wherein the power meter also has an electric parameter measuring function, namely the phase angles of voltage and current, namely the voltage and current phase angles for short, which are also marked by the middle-high-end power meter.
The voltage current phase angle and the power factor are directly related, the power factor is obtained by performing cosine operation on the parameter, but if the power factor is subjected to inverse cosine operation, the phase angle cannot be directly obtained, because the inverse cosine operation can obtain more than one angle, for example, the phase angle of the voltage and the current is 60 degrees, the power factor is 0.5, but the phase angle of the voltage and the current is-60 degrees, and the power factor is also 0.5. That is, the power factor obtained in the case of 60 degrees of voltage lead or lag current is 0.5, so that only the absolute value of the voltage current phase angle can be obtained by the parameter of the power factor, and the specific lead or lag cannot be determined. The common mode is to amplify the waveforms of the voltage and the current and then convert the amplified waveforms into square waves, and digitally detect the lead or lag of the square waves as the basis for judging the phases of the voltage and the current. However, this method is not satisfactory when the sine wave frequency is high, because the sine wave will introduce a new phase error during the square wave conversion process due to the frequency response properties of the devices such as op-amps.
Disclosure of Invention
The invention aims to provide a voltage-current phase angle distinguishing method for a power meter, which reduces the design of a hardware circuit and improves the phase identification precision.
The specific technical scheme is that the voltage and current phase angle distinguishing method for the power meter is characterized in that the voltage and current phase angle is alpha, the power factor lambda=cos alpha=P/(U.I), and the method comprises the following steps:
s100, under the detection condition, the voltage and current signals are subjected to software operation to obtain active power P, a voltage effective value U and a current effective value I, a power factor cos alpha is calculated according to cos alpha=P/(U×I),
s200, shifting the current signal by one sampling period through software, obtaining active power P' through software operation of voltage and current after phase shifting, wherein the effective value of the voltage is still U, the effective value of the current after phase shifting is still I, and then calculating a new power factor lambda New type ，
S300, calculating an angle difference beta calculated by a sampling period relative to the frequency of the current sine wave signal to be measured, further calculating sin beta and cos beta,
s400, calculating sin alpha by using a trigonometric function and a difference angle formula, and confirming a specific quadrant in which alpha is positioned according to signs of sin alpha and cos alpha to confirm the unique alpha.
Preferably, in both steps S100 and S200, the ADC collects the voltage and current signals and then performs a software operation.
Preferably, in step S200, one sampling period is 10 microseconds.
Preferably, in S300, the angular difference β=360×t/T, T representing a sampling period, and T representing a sine wave period.
Preferably, in step S200, the current signal is shifted backward by one sampling period by software, the new power factor lambda New type P'/(U x I), i.e. cos (α+β); in step S400, sin α is calculated using a trigonometric function and the angle formula cos (α+β) =cos α×cos β—sin α×sin β.
Compared with the prior art, the phase-shifting method has the advantages that the phase shifting is carried out for one sampling period, the voltage and current phase angle judgment is carried out by combining the trigonometric function and the difference angle formula, the mode of identifying the phase by using a sine wave-to-square wave circuit is abandoned, an unnecessary circuit is omitted, the material cost is reduced, and meanwhile, the identification precision is improved.
Drawings
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the invention. In the drawings:
FIG. 1 is a schematic diagram of the phase angle of the voltage and current in step S100 in example 1;
fig. 2 is a schematic diagram of the phase angle of the voltage and current after one sampling period of the backward phase shift in step S200 in embodiment 1.
Detailed Description
The present invention will be described in further detail with reference to the embodiments and the accompanying drawings, for the purpose of making the objects, technical solutions and advantages of the present invention more apparent. The exemplary embodiments of the present invention and the descriptions thereof are used herein to explain the present invention, but are not intended to limit the invention.
The voltage-current phase angle alpha and the power factor lambda are directly related, the power factor lambda is obtained by cosine operation of the parameter, the formula is lambda=cos alpha, wherein lambda=p/(u×i), and cos alpha and cos (alpha+beta) are mainly used for representing the mathematical relation between the phase angle and the power factor. In the power meter design, the phase difference between the voltage and the current is calculated by using α=arccosλ. However, because the inverse cosine operation can result in more than one angle, such as 60 degrees for the phase angles of voltage and current, 0.5 for the power factor, but-60 degrees for the phase angles of voltage and current, and 0.5 for the power factor as well. That is, the power factor obtained in the case of 60 degrees of voltage lead or lag current is 0.5, so that only the absolute value of the voltage current phase angle can be obtained by the parameter of the power factor, and the specific lead or lag cannot be determined.
A voltage-current phase angle discrimination method for a power meter, the voltage-current phase angle being α, the power factor λ=cos α=p/(u×i), comprising the steps of:
s100, under the detection condition, the voltage and current signals are subjected to software operation to obtain active power P, a voltage effective value U and a current effective value I, a power factor cos alpha is calculated according to cos alpha=P/(U.I), a phase difference is calculated by adopting alpha=arccoslambda, the voltage lead or lag current cannot be determined at the moment,
s200, shifting the current signal by one sampling period through software, in one embodiment, the sampling speed is 100ksps, one sampling period is 10 microseconds, the active power P' is obtained through voltage and current after phase shifting through software operation, the voltage effective value is still U, the current effective value after phase shifting is still I, and then the new power factor lambda is calculated New type ，
S300, calculating an angle difference beta calculated by a sampling period relative to the frequency of the current sine wave signal to be measured, further calculating sin beta and cos beta,
s400, calculating sin alpha by using a trigonometric function and a difference angle formula, confirming a specific quadrant where alpha is located according to signs of sin alpha and cos alpha, confirming a unique alpha, and determining voltage lead or lag current.
In one embodiment, in both steps S100 and S200, the voltage and current signals are collected by the ADC and then subjected to a software operation. The method always uses the signals sampled by the ADC to operate, and the signal delay of a sine wave-to-square wave circuit does not exist in the operation process, and a new phase error is not generated in the whole process, so that the accuracy of phase identification is ensured.
In one embodiment, in S300, the angular difference β=360×t/T, T representing a sampling period, and T representing a sine wave period. When the frequency is 50Hz, the sine wave period T is 20 milliseconds, and when the sampling period T is 10 microseconds, the angular difference beta is calculated to be 0.18 degrees.
Example 1: a voltage-current phase angle discrimination method for a power meter, the voltage-current phase angle being α, cosα=p/(u×i), comprising the steps of:
under the detection condition, the voltage and current signals are subjected to software operation to obtain active power P, a voltage effective value U and a current effective value I, and cos alpha is calculated according to cos alpha=P/(U×I), as shown in figure 1, the phase difference between the voltage effective value U and the current effective value I is alpha,
s200, a current signal is backward phase-shifted by one sampling period through software, the active power P 'is obtained through voltage and phase-shifted current through software operation, the voltage effective value is still U, the phase-shifted current effective value is still I, then cos (alpha+beta) is calculated according to the formula cos (alpha+beta) =P'/(U x I), as shown in FIG. 2, the current signal is backward phase-shifted by one sampling period on the basis of S100, the phase difference between the voltage effective value U and the current effective value I is changed into (alpha+beta),
s300, calculating an angle difference beta calculated by a sampling period relative to the frequency of the current sine wave signal to be measured, further calculating sin beta and cos beta,
s400, calculating sin α by using trigonometric function and angle formula cos (α+β) =cos α×cos β—sin α×sin β, determining the specific quadrant in which α is located according to sin α and cos α signs, determining the unique α, and determining the voltage lead or lag current.
Example 2: unlike example 1, in step S200, the current signal is shifted forward by one sample period by software, the new power factor λ New type P'/(U x I), i.e. cos (α - β); in step S400, sin α is calculated using the trigonometric function difference angle formula cos (α - β) =cos α+sin α.
Wherein, for the formula cosα=p/(u×i) correlation description:
the voltage-current phase angle alpha and the power factor lambda are directly related, and the power factor lambda is obtained by cosine operation of the parameter, and the formula is lambda=cos alpha, and lambda=P/(U.I).
Prompting:
(1) u (n) represents a voltage transient;
(2) i (n) represents a current instantaneous value;
(3) n represents an nth measurement interval;
(4) AVG [ ] means that the sampled data in [ ] is simply averaged over the data measurement period.
The sampling and operation process is approximately as follows:
s1, using an FPGA as an interface unit of a CPU and an ADC (analog-to-digital converter), respectively and synchronously reading ADC sampling digital quantities of a voltage signal and a current signal at a speed of 100ksps, and then generating an external interrupt to inform the CPU of reading;
s2, carrying out corresponding operation after the CPU obtains the digital quantity, if the voltage signal is subjected to square root equalizing operation to obtain a voltage effective value U, the current signal is subjected to square root equalizing operation to obtain a current effective value I, and the instantaneous values synchronously sampled by the voltage and the current signals are multiplied point by point and accumulated to obtain active power P, wherein the active power P is divided by the product of the voltage effective value U and the current effective value I to obtain a power factor lambda;
s3, each sampled current instantaneous value is always multiplied by the last sampled voltage instantaneous value and accumulated to obtain new active power, and the new active power is divided by the product of the voltage effective value and the current effective value to obtain a new power factor;
s4, the cosine value of the phase angle can be calculated by using the formula introduced in the above part, and whether the voltage is the leading current or the lagging current is further judged according to the judging method in the application.
The above description is only of the preferred embodiments of the present invention and is not intended to limit the invention in any way, and any person skilled in the art may make modifications or alterations to the equivalent embodiments using the technical disclosure described above. However, any simple modification, equivalent variation and variation of the above embodiments according to the technical substance of the present invention still fall within the protection scope of the technical solution of the present invention.
Claims (4)
1. A method for discriminating the phase angle of a voltage and a current for a power meter, the phase angle of the voltage and the current being α, the power factor l=cos α=p/(u×i), characterized by comprising the steps of:
s100, under the detection condition, the voltage and current signals are subjected to software operation to obtain active power P, a voltage effective value U and a current effective value I, a power factor cos alpha is calculated according to cos alpha=P/(U×I),
s200, shifting the current signal by one sampling period through software, obtaining active power P' through software operation of voltage and current after phase shifting, wherein the effective value of the voltage is still U, the effective value of the current after phase shifting is still I, and then calculating a new power factor l New type The current signal is backward phase-shifted by one sampling period by software, and the new power factor l New type P'/(U x I), i.e. cos (a + beta),
s300, calculating an angle difference beta calculated by a sampling period relative to the frequency of the current sine wave signal to be measured, further calculating sin beta and cos beta,
s400, calculating sin α by using trigonometric function and angle formula cos (α+β) =cos α×cos β—sin α×sin β, and determining the specific quadrant in which α is located according to sin α and cos α signs, and determining the unique α.
2. The method according to claim 1, wherein in steps S100 and S200, the ADC collects voltage and current signals and performs a software operation.
3. The method according to claim 1, wherein in step S200, one sampling period is 10 μs.
4. The method according to claim 1, wherein in S300, the angular difference β=360×t/T, T represents a sampling period, and T represents a sine wave period.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111399033.4A CN114167135B (en) | 2021-11-19 | 2021-11-19 | Voltage-current phase angle distinguishing method for power meter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202111399033.4A CN114167135B (en) | 2021-11-19 | 2021-11-19 | Voltage-current phase angle distinguishing method for power meter |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN114167135A CN114167135A (en) | 2022-03-11 |
| CN114167135B true CN114167135B (en) | 2023-07-21 |
Family
ID=80480106
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202111399033.4A Active CN114167135B (en) | 2021-11-19 | 2021-11-19 | Voltage-current phase angle distinguishing method for power meter |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN114167135B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN117879179B (en) * | 2024-03-11 | 2024-06-11 | 西安热工研究院有限公司 | Electrical equipment abnormal power state monitoring method and system |
Citations (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4075698A (en) * | 1974-04-01 | 1978-02-21 | Lode Tenny D | Digital phase measurement system |
| CN1038378A (en) * | 1988-04-12 | 1989-12-27 | 根本企画工业株式会社 | Antenna assembly and attitude control method thereof |
| CN1077831A (en) * | 1991-12-23 | 1993-10-27 | 艾利森电话股份有限公司 | Be used in particular for the phase shift of the clock signal of digital data signal clock recovery |
| US5294841A (en) * | 1990-12-28 | 1994-03-15 | Thomson Composants Microondes | Method of shifting the phase of an electrical signal and a phase-shifter based on this method |
| CN1242836A (en) * | 1997-05-19 | 2000-01-26 | 施蓝姆伯格资源管理服务公司 | Electronic revenue meter with automatic service sensing |
| JP2000077990A (en) * | 1998-09-03 | 2000-03-14 | Victor Co Of Japan Ltd | Digital phase comparator |
| CN1321248A (en) * | 1999-07-02 | 2001-11-07 | 通用电气公司 | Method and apparatus for real time measurement of three phase electrical parameters |
| CN101310498A (en) * | 2006-02-03 | 2008-11-19 | 安立股份有限公司 | Phase control device, and pulse pattern generator and error detector using the phase control device |
| CN102288821A (en) * | 2011-04-29 | 2011-12-21 | 北京合康亿盛变频科技股份有限公司 | Measuring method, measuring device, measuring procedure and carrier for phase difference of three-phase circuit |
| CN102721859A (en) * | 2012-07-09 | 2012-10-10 | 上海稳利达科技股份有限公司 | Power factor sampling controller for three-phase transmission line in electric power system and control method thereof |
| CN109066698A (en) * | 2018-08-13 | 2018-12-21 | 合肥工业大学 | A kind of calculation method of network voltage instantaneous phase angle |
| CN111542155A (en) * | 2020-04-24 | 2020-08-14 | 武汉理工大学 | Household LED lighting circuit |
| CN213461544U (en) * | 2020-09-10 | 2021-06-15 | 青岛仪迪电子有限公司 | DC-DC isolation power supply circuit for high-precision power meter |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9733288B2 (en) * | 2015-10-02 | 2017-08-15 | Continental Automotive Systems, Inc. | Apparatus and method for determining a resonant frequency of an LC circuit in situ, by comparing voltage and current polarity changes |
| US10782329B2 (en) * | 2017-09-27 | 2020-09-22 | Marcdevices Co., Ltd. | Phase analysis circuit |
-
2021
- 2021-11-19 CN CN202111399033.4A patent/CN114167135B/en active Active
Patent Citations (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4075698A (en) * | 1974-04-01 | 1978-02-21 | Lode Tenny D | Digital phase measurement system |
| CN1038378A (en) * | 1988-04-12 | 1989-12-27 | 根本企画工业株式会社 | Antenna assembly and attitude control method thereof |
| US5294841A (en) * | 1990-12-28 | 1994-03-15 | Thomson Composants Microondes | Method of shifting the phase of an electrical signal and a phase-shifter based on this method |
| CN1077831A (en) * | 1991-12-23 | 1993-10-27 | 艾利森电话股份有限公司 | Be used in particular for the phase shift of the clock signal of digital data signal clock recovery |
| CN1242836A (en) * | 1997-05-19 | 2000-01-26 | 施蓝姆伯格资源管理服务公司 | Electronic revenue meter with automatic service sensing |
| JP2000077990A (en) * | 1998-09-03 | 2000-03-14 | Victor Co Of Japan Ltd | Digital phase comparator |
| CN1321248A (en) * | 1999-07-02 | 2001-11-07 | 通用电气公司 | Method and apparatus for real time measurement of three phase electrical parameters |
| CN101310498A (en) * | 2006-02-03 | 2008-11-19 | 安立股份有限公司 | Phase control device, and pulse pattern generator and error detector using the phase control device |
| CN102288821A (en) * | 2011-04-29 | 2011-12-21 | 北京合康亿盛变频科技股份有限公司 | Measuring method, measuring device, measuring procedure and carrier for phase difference of three-phase circuit |
| CN102721859A (en) * | 2012-07-09 | 2012-10-10 | 上海稳利达科技股份有限公司 | Power factor sampling controller for three-phase transmission line in electric power system and control method thereof |
| CN109066698A (en) * | 2018-08-13 | 2018-12-21 | 合肥工业大学 | A kind of calculation method of network voltage instantaneous phase angle |
| CN111542155A (en) * | 2020-04-24 | 2020-08-14 | 武汉理工大学 | Household LED lighting circuit |
| CN213461544U (en) * | 2020-09-10 | 2021-06-15 | 青岛仪迪电子有限公司 | DC-DC isolation power supply circuit for high-precision power meter |
Non-Patent Citations (2)
| Title |
|---|
| "基于部分移相网络级联的传输线远端串扰消除技术";娄千层;《电工技术学报》;全文 * |
| "数字相位测量仪设计与开发";刘竹;《中国优秀硕士学位论文全文数据库》;全文 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN114167135A (en) | 2022-03-11 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN114167135B (en) | Voltage-current phase angle distinguishing method for power meter | |
| CN101420228B (en) | Method and device for multi-range analog/digital conversion | |
| JP3508718B2 (en) | Rotation angle detector | |
| JPS61292067A (en) | Method for measuring electric energy | |
| CN109470389A (en) | Strain-type torch measuring system and method | |
| EP0058050B1 (en) | Measuring method | |
| KR101203041B1 (en) | Method of measuring an amplitude of a sinusoidal wave using a phase difference and apparatus thereof | |
| CN111999559B (en) | Digital linear phase comparison method based on double ADCs | |
| JP4350488B2 (en) | Voltage, current, active power, reactive power, frequency measuring device and measuring method in power system | |
| US6469492B1 (en) | Precision RMS measurement | |
| CN111208346B (en) | Small signal voltage measuring device and method | |
| CN114019222B (en) | Half-wave detection method for high-precision measurement of residual current | |
| CN110763915A (en) | Method for calculating voltage included angle and zero line current and three-phase electric energy meter | |
| JP2995769B2 (en) | How to measure electrical variables | |
| JP3082124B2 (en) | Electromagnetic flow meter | |
| KR20080081392A (en) | Method for measuring line to line voltage using an interpolation | |
| US4654585A (en) | Phase detection method | |
| CN110596456A (en) | Power grid frequency testing method | |
| EP0465476A1 (en) | A sampling circuit | |
| CN108037352B (en) | Method and system for improving electric energy measurement accuracy | |
| JPH0782044B2 (en) | Power converter | |
| CN116298472A (en) | Busbar current determining method, device and system | |
| JPH11287829A (en) | Digital power measuring device | |
| SU1241146A1 (en) | Method of indicating quadrature phase shift | |
| SU847218A1 (en) | Method of measuring electric signal amplitude value |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |