CN102520386B - 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 of intelligent grid transformation, intelligent electric energy meter is as the indispensable equipment of intelligent grid, demand is large, in the production of traditional three-phase intelligent electric-energy meter, intelligent electric energy meter adjustment generally adopts pulse adjustment method, pulse adjustment method has stable and accurate advantage, but pulse adjustment method need to take a large amount of time, particularly when the underloading point to high-precision electric energy meter carries out adjustment, although the way that can accelerate by pulse reduces the time of adjustment, but the reliability of pulse accelerated process is not fine, the shortcoming such as not easy to operate, thereby cause the production difficulty of three-phase intelligent electric-energy meter large, efficiency is low.

Summary of the invention

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

An adjusting process for three-phase electric energy meter, its special feature is, comprises the steps:

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

(2), the PC measuring parameter data that read matrix by RS485 communication interface with by the three-phase electric energy meter of adjustment, synchronizeed, realize and being arranged by the parameter of adjustment electric energy meter;

(3), electric current and voltage source PF=0.5L, during rated output voltage electric current, PC is to by the three-phase electric energy meter of adjustment broadcast adjustment voltage, electric current and A, B, C phase channel gain and phase correction commands, and electric energy meter completes 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, 20% current work point of rated current, PC is to being broadcasted underloading point A, B, C phase phase correction commands by adjustment electric energy meter, and electric energy meter completes 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, after PC broadcasting command, electric energy meter is read unloaded effective value, performance number, then calculates according to quiescent value the value that corresponding OFFSET value is inserted corresponding OFFSET register, completes A, B, C phase OFFSET correction.

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

Accompanying drawing explanation

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 as follows:

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

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

During voltagerating input, the voltage effective value register value of standard should both facilitate MCU to convert LCD displayed value to, again in the zone of reasonableness of channel phases 1.0Ib.

While supposing voltagerating input Un, chip voltage passage input terminal voltage effective value is Vu, and calculated value is U _theoretical, through MCU, change LCD displayed value into U _{indicating value}, the voltage effective value register value of standard is U _standard, U _standardselection should meet following condition:

0.8 < U _standard/ U _theoretical< 1.2

K=U _standard/ U _theoretical, K should be integer and is convenient to MCU conversion

Above-mentioned first condition guarantees that U channel phases 1.0Ib is a rational scope, and choosing of second condition K should facilitate MCU to convert effective value register value to LCD displayed value.If PGA=1 wherein, 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

While calculating current rating input by 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, the parameters such as active power value P, the electric meter constant EC of standard 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, 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: electric meter 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, 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 ':

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 by configuration GSUA register, and the computing method of GSUA are as follows:

USGain＝(-ErrUA)/(1+ErrUA)

If USGain >=0, GSUA=INT[USGain*2 ¹⁵]

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

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

4, channel phases 0.5LIb

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

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

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

θ,

$\mathrm{\&theta;}=\mathrm{Arc}\sin \frac{-\mathrm{ErrPA}}{\sqrt{3}}$

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

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

If adjust PHSUA register, have PHSUA=0x80+INT (θ/0.017578 °)

If adjust PHSIA register and do not consider Stepwise calibration, having:

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, supposes as the mutually desirable active power of 1 calculating A is PA _0.5L0.2Ib, reading actual active power is PA _0.5L0.2Ibfor PA _0.5L0.2Ib', the active power error that A is brought by phase error is:

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

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

θ,

$\mathrm{\&theta;}=\mathrm{Arc}\sin \frac{-\mathrm{ErrPA}}{\sqrt{3}}$

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

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

If adjust PHSUA register, have PHSUA=0x80+INT (θ/0.017578 °)

If adjust PHSIA register and do not consider Stepwise calibration, having:

PHSIA_R1[7:0]＝0x80-INT(θ/0.017578°)

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

7, according to above theory, in by the intelligent electric energy meter of adjustment, do corresponding adjustment 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 sample 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 analog channel gain is 1 times.

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

A, voltage effective value register theoretical value while 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, through MCU, change LCD displayed value into U _{indicating value}=220V, can select U _standardbe that 44000000, MCU can change easily

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

A, current effective value register theoretical value while 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, through MCU, change LCD displayed value into I _{indicating value}=1.5A, can select I _standardbe that 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, ErrUA=(UA '-UA)/UA=(37297350-44000000)/7500000=-0.152333 so, 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, ErrIA=(IA '-IA)/IA=(8299685-7500000)/7500000=0.106625 so,-ErrIA/ (1+ErrIA)=-0.0963515 writes INT[65536-0.0963515*32768 in register GSIA]=F3ABH; Current effective value can be proofreaied and correct is like this 7500000, and correction error can be controlled at 0.02%～0.03%.

After A phase voltage effective value and current effective value have been proofreaied and correct, be correlated with effective value, power etc. of active power/reactive power/first-harmonic have all been proofreaied and correct.Because HFconst is the 3E73H being extrapolated by standard active power, thus A phase voltage error also automatic calibration complete.

The same process of the interdependent photograph of B phase and C is proofreaied and correct.

(6), channel phases 0.5LIb process

After the complete 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 _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, being converted to 16 systems is 0x8E

The same process of the interdependent photograph of B phase and C is 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. an adjusting process for three-phase electric energy meter, is characterized in that, comprises the steps:

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

(2), the PC measuring parameter data that read matrix by RS485 communication interface with by the three-phase electric energy meter of adjustment, synchronizeed, realize and being arranged by the parameter of adjustment electric energy meter;

(3), electric current and voltage source PF=0.5L, during rated output voltage electric current, PC is to by the three-phase electric energy meter of adjustment broadcast adjustment voltage, electric current and A, B, C phase channel gain and phase correction commands, and electric energy meter completes 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, 20% current work point of rated current, PC is to being broadcasted underloading point A, B, C phase phase correction commands by adjustment electric energy meter, and electric energy meter completes 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, after PC broadcasting command, electric energy meter is read unloaded effective value, performance number, then calculates according to quiescent value the value that corresponding OFFSET value is inserted corresponding OFFSET register, completes A, B, C phase OFFSET correction.

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