CN102520386A - Calibration method of three-phase electric energy meter - Google Patents

Abstract

The invention relates to a calibration method of a three-phase electric energy meter. The calibration method comprises the following steps that: (1) first taking a voltage current source of which the accuracy class is higher than the class requested by a tested electric energy meter, a PC (Personal Computer) machine used for issuing synchronous orders for the voltage current source and the electric energy meter, a mother meter as a reference and a three-phase electric energy meter needing to be calibrated; (2) the PC machine reads a measurement parameter data of the mother meter through an RS 485 communicating interface to be synchronous with the calibrated three-phase electric energy meter, and the parameter setting of the calibrated three-phase electric energy meter is realized; and (3) the voltage current source PF is equal to 0.5L, wherein when the voltage current source outputs rated voltage and current, the PC machine broadcasts calibrating voltage, calibrating current, a channel gaining order of an A phase, a B phase and C phase and a phase correction order for the calibrated three-phase electric energy meter. The invention discloses an automatic calibration method of a three-phase intelligent electric energy meter, which combines a meter calibrating method with power and a traditional meter calibrating method with pulses. Therefore, the production difficulty of the three-phase intelligent electric energy meter is greatly reduced, and the production efficiency is increased.

Description

The adjusting process of three-phase electric energy meter

Technical field

The present invention relates to a kind of adjusting process of three-phase electric energy meter.

Background technology

In recent years, under the overall situation that intelligent grid is transformed, intelligent electric energy meter is as the indispensable equipment of intelligent grid; Demand is big, and in the production of traditional three-phase intelligent electric energy meter, pulse adjustment method is generally adopted in the intelligent electric energy meter adjustment; Pulse adjustment method has stable and accurate advantage, but pulse adjustment method need take great amount of time, particularly when the underloading point to high-precision electric energy meter carries out adjustment; Though can reduce the time of adjustment through the way that pulse is quickened, shortcoming such as the reliability of pulse accelerated process is not fine, and is not easy to operate; Thereby cause the production difficulty of three-phase intelligent electric energy meter big, efficient is low.

Summary of the invention

The purpose of this invention is to provide a kind of simply, fast, the adjusting process of three-phase electric energy meter accurately.

A kind of adjusting process of three-phase electric energy meter, its special feature is, comprises the steps:

(1), at first get an accuracy class and be higher than the electric current and voltage source of tested electric energy meter institute calling hierarchy, give the PC of electric current and voltage source with electric energy meter issue synch command for one, one as the matrix of reference with need the three-phase electric energy meter of adjustment;

(2), PC read matrix through the RS485 communication interface the measuring parameter data with synchronous by the three-phase electric energy meter of adjustment, realize by the parameter setting of adjustment electric energy meter;

(3), electric current and voltage source PF=0.5L; During the rated output voltage electric current; PC is to by the three-phase electric energy meter of adjustment broadcasting adjustment voltage, electric current and A, B, C phase channel gain and phase correction commands, and electric energy meter is accomplished the adjustment of above debug point according to the information in electric current and voltage source;

(4), electric current and voltage source PF=0.5L; Output rated voltage; The 20% current work point of rated current, PC is to being broadcasted underloading point A, B, C phase phase correction commands by the adjustment electric energy meter, and electric energy meter is accomplished the adjustment of the error of above underloading point according to the information in electric current and voltage source;

(5), electric current and voltage source electric current is unloaded; Output rated voltage; Electric energy meter is read unloaded effective value, performance number behind the PC broadcasting command, calculates the value that corresponding OFFSET value is inserted corresponding OFFSET register according to quiescent value again, accomplishes A, B, C phase OFFSET correction.

The present invention is the automatic adjusting process that adopts a kind of three-phase intelligent electric energy meter that the power calibration combines with traditional pulse calibration method, thereby reduces the production difficulty of three-phase intelligent electric energy meter greatly, enhances productivity.

Description of drawings

Accompanying drawing 1 is the process flow diagram of adjusting process of the present invention;

Accompanying drawing 2 is the logic theory block diagram of adjustment system of the present invention.

Embodiment

The principle of the inventive method is following:

1, normal voltage electric current and active power value are calculated:

(1), the voltage effective value register value of calculating and choice criteria

The voltage effective value register value of standard should both make things convenient for MCU to convert the LCD displayed value to during the voltagerating input, again in the zone of reasonableness of channel phases 1.0Ib.

When supposing voltagerating input Un, chip voltage passage input terminal voltage effective value is Vu, and calculated value is U _Theoretical, be U through MCU conversion LCD displayed value _{Indicating value}, the voltage effective value register value of standard is U _Standard, U then _StandardSelection should be satisfied following condition:

0.8＜U _Standard/ U _Theoretical＜1.2

K=U _Standard/ U _Theoretical, K should be integer and is convenient to the MCU conversion

Above-mentioned first condition guarantees U channel phases 1.0Ib a reasonable range, and choosing of second condition K should make things convenient for MCU to convert the effective value register value to the LCD displayed value.Wherein if PGA=1, U _TheoreticalCan be calculated as follows:

U _Theoretical=INT [(Vu/800) * 2^27]

(2), the current effective value register value of calculating and choice criteria

When calculating the specified input of electric current with same principle, the current effective value register value I of standard _Standard

(3), calculate PF=1.0Ib, PF=0.5L Ib and PF=0.5L 0.2Ib, the active power register value of standard

Specified input, PF=1.0Ib, the active power effective value P of standard _1.0Ib=INT (U _Standard* I _Standard/ 2^31)

Specified input, PF=0.5L Ib, the active power effective value P of standard _0.5LIb=INT (U _Standard* I _Standard/ 2^32)

Specified input, PF=0.5L 0.2Ib, the active power effective value P of standard _0.2L0.5Ib=0.2INT (U _Standard* I _Standard/ 2^32)

2, HFConst calculates:

According to PF=1.0Ib, parameters such as the active power value P of standard, ammeter constant EC are calculated as follows theoretical HFConst value:

HFConst＝INT[P*3.6*10^6*Fosc/(32*EC*Un*Ib*2^31)]

P:PF=1.0Ib is by 3) the active power register value of the standard calculated

Fosc: crystal frequency, recommend external 8.192Mhz crystal

Un: specified input voltage

Ib: the electric current of specified input

EC: ammeter constant

By result of calculation configuration HFConst1 and HFConst2 register.

3, channel phases 1.0Ib

The specified output in electric current and voltage source, suppose as 1 in to calculate A phase normal voltage effective value be UA, the normalized current effective value is IA, reading A phase virtual voltage effective value register value is that UA ', actual current effective value register value are IA ', then:

A phase voltage effective value error E rrUA=(UA '-UA)/UA

A phase current effective value error E rrIA=(IA '-IA)/IA

A phase U channel phases 1.0Ib can realize that the computing method of GSUA are following through configuration GSUA register:

USGain＝(-ErrUA)/(1+ErrUA)

If USGain＞=0, then GSUA=INT [USGain*2 ¹⁵]

Otherwise USGain＜0, then GSUA=INT [2 ¹⁶+ USGain*2 ¹⁵]

A phase I channel power correcting gain can be realized the same GSUA of method through configuration GSIA register

4, channel phases 0.5LIb

Electric current and voltage source configuration change is PF=0.5L Ib, and specified output is supposed as the mutually desirable active power of 1 calculating A is PA _0.5LIb, reading actual active power is PA _0.5LIbBe PA _0.5LIb', then the active power error brought by phase error of A is:

ErrPA＝(PA _0.5LIb’-PA _0.5LIb)/PA _0.5LIb

This error can realize through configuration A phase U channel phases 0.5LIb register PHSUA or I channel phases 0.5LIb register PHSIA.Phase compensation formula: do as if A phase U, the interchannel angular difference of I

θ, then

$\mathrm{\θ}=\mathrm{Arc}\sin \frac{-\mathrm{ErrPA}}{\sqrt{3}}$

If θ＞0, the leading IA of expression UA; If θ＜0, expression UA hysteresis IA.

To 50Hz, PHSUA and PHSIA register all have the relation of 0.017578 °/LSB.

If adjustment PHSUA register, PHSUA=0x80+INT (θ/0.017578 °) is arranged then

If adjust the PHSIA register and do not consider the segmentation correction, then have:

PHSIA_R1[7:0]＝0x80-INT(θ/0.017578°)

5, channel phases 0.5L0.2Ib

Electric current and voltage source configuration change is PF=0.5L 0.2Ib, and specified output is supposed as the mutually desirable active power of 1 calculating A is PA _0.5L0.2Ib, reading actual active power is PA _0.5L0.2IbBe PA _0.5L0.2Ib', then the active power error brought by phase error of A is:

ErrPA＝(PA _0.5L0.2Ib’-PA _0.5L0.2Ib)/PA _0.5L0.2Ib

This error can realize through configuration A phase U channel phases 0.5L0.2Ib register PHSUA or I channel phases 0.5L0.2Ib register PHSIA.Phase compensation formula: do as if A phase U, the interchannel angular difference of I

θ, then

$\mathrm{\θ}=\mathrm{Arc}\sin \frac{-\mathrm{ErrPA}}{\sqrt{3}}$

If θ＞0, the leading IA of expression UA; If θ＜0, expression UA hysteresis IA.

To 50Hz, PHSUA and PHSIA register all have the relation of 0.017578 °/LSB.

If adjustment PHSUA register, PHSUA=0x80+INT (θ/0.017578 °) is arranged then

If adjust the PHSIA register and do not consider the segmentation correction, then have:

PHSIA_R1[7:0]＝0x80-INT(θ/0.017578°)

6, according to above theory, produce some of the three-phase intelligent electric energy matrixs of various current specification, use during the intelligent electric energy meter adjustment that supplies different size.

7, in by the intelligent electric energy meter of adjustment, do corresponding adjustment according to above theory and realize program and signal procedure.

8, the control program of design PC end, so that PC realizes matrix, standard scale and by the control of adjustment table.

9, power calibration method for example

Suppose that a design 220V (Un), the specified input of 1.5A (In), table constant are the appearance table of 3200 (EC).Rated voltage Un=220V, requiring corresponding A DC input end signal amplitude is Vn=220mV; Rated current Ib=1.5A; Corresponding A DC input end signal amplitude is Vi=50mV, and the analog channel gain is 1 times.

(1), normal voltage effective value register value calculates and selects

A, voltage effective value register theoretical value when calculating specified input

According to formula U _Theoretical=INT [(Vu/800) * 2^27], substitution Vn=220mV,

U _Theoretical=INT [(220/800) * 2^27]=36909875

B, according to condition 0.8＜U _Standard/ U _Theoretical＜1.2, U _TheoreticalReasonable choice range is 29527900～44291850

C, be U through MCU conversion LCD displayed value _{Indicating value}=220V can select U _StandardBe 44000000, MCU can change easily

(2), normalized current effective value register value calculates and selects

A, current effective value register theoretical value when calculating specified input

According to formula I _Theoretical=INT [(Vi/800) * 2^27], substitution Vu=50mV,

I _Theoretical=INT [(50/800) * 2^27]=8388608

B, according to condition 0.8＜I _Standard/ I _Theoretical＜1.2, I _TheoreticalReasonable choice range is 6710886～10066329

C, be I through MCU conversion LCD displayed value _{Indicating value}=1.5A can select I _StandardBe 7500000, MCU can change easily

(3), PF=1.0Ib, PF=0.5LIb and PF=0.5L0.2Ib, standard active power register value calculates

Specified input, PF=1.0, the active power value of standard

P _1.0Ib=INT (U _Standard* I _Standard/ 2^31)=44000000*7500000/2^23=39339066

Specified input, PF=0.5L, the active power value of standard

P _0.5LIb=INT (U _Standard* I _Standard/ 2^32)=39339066/2=19669533

Specified input, PF=0.2L, the active power value of standard

P _0.5L0.2Ib=0.2INT (U _Standard* I _Standard/ 2^32)=19669533*0.2=3933906

(4), HFConst calculates and configuration

By formula: HFConst=INT [P*3.6*10^6*Fosc/ (32*EC*Un*Ib*2^31)]

＝INT[(39339066*3.6*8.192*10^12)/(32*3200*220*1.5*2^31)]

＝15987

＝3E73H

So chip configuration HFConst1=HFConst2=3E73H

(5), channel phases 1.0Ib process

The specified output in electric current and voltage source; Read A phase voltage effective value register; Be assumed to be 37297350; So ErrUA=(UA '-UA)/UA=(37297350-44000000)/7500000=-0.152333, in register GSUA, write-ErrUA/ (1+ErrUA)=0.1321953*32768=4332, correction error can be controlled at 0.02%～0.03%.

Read A phase current effective value register; Be assumed to be 8299685; So ErrIA=(IA '-IA)/IA=(8299685-7500000)/7500000=0.106625;-ErrIA/ (1+ErrIA)=-0.0963515 writes INT [65536-0.0963515*32768]=F3ABH in register GSIA; Can proofread and correct current effective value like this is 7500000, and correction error can be controlled at 0.02%～0.03%.

After A phase voltage effective value and current effective value were proofreaied and correct and accomplished, be correlated with effective value, power etc. of active power/reactive power/first-harmonic were all proofreaied and correct completion.Because HFconst is the 3E73H that is extrapolated by standard active power, so A phase voltage error is also accomplished from NMO correction.

B phase and the interdependent photograph of C process are together proofreaied and correct.

(6), channel phases 0.5LIb process

Behind the intact channel phases 1.0Ib in school, change power factor into 0.5L Ib, the value of reading A phase active power register is 9526535,

ErrPA=(PA then _0.5LIb'-PA _0.5LIb)/PA _0.5LIb=(19526535-19669533)/19669533=-0.00727

θ＝ArcSin(-(-0.00727)/1.732)＝ArcSin0.0042＝0.2406°。

PHSUA=128+INT [0.2406/0.017578]=142, converting 16 systems into is 0x8E

B phase and the interdependent photograph of C process are together proofreaied and correct.

(7), channel phases 0.5L0.2Ib process

Channel phases 0.5L0.2Ib reference channel phase place 0.5LIb process.

Claims (1)

1. the adjusting process of a three-phase electric energy meter is characterized in that, comprises the steps:

(1), at first get an accuracy class and be higher than the electric current and voltage source of tested electric energy meter institute calling hierarchy, give the PC of electric current and voltage source with electric energy meter issue synch command for one, one as the matrix of reference with need the three-phase electric energy meter of adjustment;

(2), PC read matrix through the RS485 communication interface the measuring parameter data with synchronous by the three-phase electric energy meter of adjustment, realize by the parameter setting of adjustment electric energy meter;

(3), electric current and voltage source PF=0.5L; During the rated output voltage electric current; PC is to by the three-phase electric energy meter of adjustment broadcasting adjustment voltage, electric current and A, B, C phase channel gain and phase correction commands, and electric energy meter is accomplished the adjustment of above debug point according to the information in electric current and voltage source;

(4), electric current and voltage source PF=0.5L; Output rated voltage; The 20% current work point of rated current, PC is to being broadcasted underloading point A, B, C phase phase correction commands by the adjustment electric energy meter, and electric energy meter is accomplished the adjustment of the error of above underloading point according to the information in electric current and voltage source;

(5), electric current and voltage source electric current is unloaded; Output rated voltage; Electric energy meter is read unloaded effective value, performance number behind the PC broadcasting command, calculates the value that corresponding OFFSET value is inserted corresponding OFFSET register according to quiescent value again, accomplishes A, B, C phase OFFSET correction.