EC-RASP: A new Elec ical Ene gy S a ic Coun e based on
Random Signal P ocessing
S. To al, J. M. Que o and L. G. F anquelo
Dp o. de Ingenie ´ıaElec ´
onica
EscuelaSupe io de Ingenie os,
A da. ReinaMe cedes s/n, Se illa–41012(SPAIN)
Tel.: +34(9)5 45568 57
FAX: +34(9)5 45568 49
e–mail: [email p o ec ed]
Con e ence Topic: IC’s o ins umen a ion and con ol
Abs ac — Thispape conce ns hedesignandde elopmen o elec i-
cal ene gy s a ic coun e , based on andom pulse s eam p ocessing.
Measu emen p oceeding, calib a ionand ha dwa e implemen a ion
a e checked in a p o o ype. As a esul , a simple low cos measu e-
men sys em has been ob ained. The esul ing measu es ha e been
compa ed wi h he ones ob ainedusing a poly phase comme cialan-
alyze . A maximum 2% e o has been achie ed. This measu emen
p oceedingis pa en pending.
I. STATE OF ART
His o ically he moni o ing o elec ical ene gy
consump ion has been done by a ious ypes o
induc ion wa me e s. The con en ional induc-
ion wa me e , wi h o a ing disc and sha , con-
ains a mechanical egis e (d i en by a gea on
he sha ) which con inuously displays he o al
accumula ed kilowa hou s consumed. Swi ch o
clu ch ac i able mechanical demand and ime o
use egis e s a e also used on hese me e s o dis-
play demand and ime o use quan i ies.
Elec onic egis e s a e in common use odaywi h
induc ion ype wa me e , o accumula e pulse
da a p opo ional o powe consump ion. This
pulse da a is usually p o ided o he egis e om
an op ical pick up o senso de ice which senses
me e disc o a ion. These egis e s ha e he ad-
an age ha hey can pe o m calcula ions on ac-
cumula ed pulse da a and elec onically display
much mo e in o ma ion han ispossiblewi h con-
en ional mechanical ype egis e s.
Nowadays, be e pe o mances a e equi ed and
achie ed using s a ic coun e s. In his sense, elec-
ic companiesha e oundi desi able omeasu e,
in addi ion o o al kilowa -hou s, powe ac o ,
KVA, o eac i e ol ampe es. The measu emen
o eac i e ol ampe es ypically has been accom-
plished by using a second me e in conjunc ion
wi h he con en ional kilowa -hou me e . F om
he eac i e ol ampe esand he eal ol ampe es,
quan i ies such as powe ac o and KVA can be
calcula ed. This second me e o measu emen
o eac i e ol ampe es is a wa me e connec ed
wi hphaseshi ing ans o me sin he ol ageci -
cui s.
I is also in e es ing o p o ide he capabili y o
digi ally con igu e he me e o measu e elec ic
ene gy low in any o he di e en elec ical se -
ices. Finally, i is desi able he possibili yo con-
nec ing o ei he single phaseo poly phasepowe
line sys ems. All hese cha ac e is ics should be
accomplished by low cos and p ecise simple de-
ices.
P esen ly, elec onic coun e s and wa me e s use
ei he analog ci cui s, o an analog o digi al con-
e sion, ollowed by a pu e digi al p ocessing,
basedonmic op ocesso sys ems,mic ocon olle
sys emso digi al signal p ocesso (DSP).
In he ollowing,se e alpa en sa edesc ibed. Eu-
opean pa en No. 94110967.0[1] desc ibes a s a ic
kWh me e ha makes use o an analog mul i-
plie . F om he pulse-wid h modula ed ol age, a
pulse-wid h/pulse-heigh modula ed signal, p o-
po ional o he powe , is gene a ed, using analog
connec o s. A equency signal is hus ob ained,
which is passed h ough a di ide ci cui o he
coun e o he kWh me e o de e mina ion o he
ene gy ha has been consumed. Analog connec-
o sha eade imen alp ope y, because heyp o-
duce ex a ol age and cu en pulses in he signal
o be measu ed. So, i is necessa y o compensa e
his e ec , including an addi ional elec onic o
sol e he p oblem. Besides, ypical disad an ages
o analogelec onic de ices a e p esen : noisesen-
si i eness, he mical sensi i eness, manu ac u e
ole ances
:::
Eu opean pa en No. 94203283.0 [1] uses a digi al
signal p ocesso om he analog odigi al con e -
sion o ol age and cu en . High numbe o pe -
o mances a e achie ed a he expenses o a high
cos de ice.
In his pape a new s a ic ene gy coun e is p e-
sen ed. Tha is, a coun e in which bo h cu en
COMP
|U|
COMP
INC/DEC
I
U
|I|
(1) (2)
(3)
(4)
(6)
(7)
(8)
(9)
(10)
(11)
(12)
(13)
(15)
(14)
CAD
CAD
sign(I)
10
10
10
10
U
II
ld
m
e
l
m
U
d
I
e
U
e
(5)
sign(U)
SENSOR
NUMBER
GENERATOR
RANDOM COUNTER
Figu e 1: De ailed block diag am
and ol age change p ope ies o solid s a e elec-
onic de ices, gene a ingpulseso equency p o-
po ional o kWh. A i s , cu en and ol age
a e sensed and digi al con e ed. S ochas ic pulse
s eams a e p oduced by compa ing hese digi al
numbe s wi h andom numbe s. The mul iplie is
achie edbyasimpleANDga e. I sou pu isa an-
dom pulse s eam ha ep esen s ins an aneous
ac i e powe . Time in eg a ion is achie ed by a
digi al coun e . I should be no iced ha s ochas-
ic signal p ocessing is en i ely digi al. In con as
wi h he las men ioned me hod ou digi al ci -
cui sa eex emelysimpleandeasilyimplemen ed
in low cos p og ammable de ices o ASICs, p e-
se ing all he pe o mances desc ibed abo e.
In he ollowing sec ions, i will be explained in
de ail he design and de elopmen o he mea-
su emen sys em. Fi s o all, i will be desc ibed
he mono phase a chi ec u e o an ac i e ene gy
coun e , ha has been implemen ed. P o o ype
cha ac e is ics, calib a ion p oceeding and illus-
a i e measu emen s will be shown nex . Finally,
possible gene aliza ions and se e al conclusions
will be wi hd awn.
II. MONO PHASE ARCHITECTURE
Figu e 2 is a simpli ied block diag am o he elec-
onic me e : Rec i ied cu en and ol age signals
a e digi al con e ed. S ochas ic pulse s eams
a e p oduced by compa ing hesedigi al numbe s
wi h andom numbe s. The mul iplie is achie ed
by a simple AND ga e. Ins an aneous powe ,
coded in he andom pulse s eam a he ou pu
o he AND ga e, is ime in eg a ed by a coun e
ha inc easesodec easesi s alueacco ding o he
mul iplying signal signs.
Figu e 1 is a de ailed logic block diag am.
Blocks (1) and (7), connec ed o he wi es o he
U
I
1
1
ADQUISITION
ADQUISITION
SIGNAL
SIGNAL
COUNTER
up/down
sign(U)
sign(I)
CONVERSION
RANDOM PULSE
RANDOM PULSE
CONVERSION
Figu e 2: Block diag am
elec ici y ne wo k gene a es measu es
U
l
and
I
l
,
p opo ional o ol age (U) and cu en (I). Blocks
(2) and (9) ec i y bo h magni udes and (3) and
(10) calcula e he sign. (4) and (11) make analog o
digi al con e sion. (5) gene a es pai s o andom
numbe oge andompulses eams
U
e
e
I
e
. AND
ga e (13) gene a es he andom pulses s eam
P
e
,
which codes ins an aneous powe . This powe is
in eg a ed by a coun e (14), which inc eases o
dec eases acco ding o ol age and cu en signs.
III. REALIZATION
In igu e3apho og apho hep o o ypeisshown:
The p o o ypeisa monophase s a icac i e ene gy
coun e . This es boa d has been de eloped as a
PC expansion boa d, in o de o debug ha dwa e
easily. The es boa d includes a cu en in e ace
wi h a i de ices, acco ding oDIN 43864. E e y
3600
W
s
, i is gene a ed a cu en pulse g ea e
han 30 ms.
Measu emen s o bo h cu en and ol age a e
aken om wo ansduce s, acco ding o igu e
4. Ac ually, ol age ansduce is no necessa y. I
could be used a simple esis o ol age di ide .
R
1
−
+
+12V
-12V
R
1
Vo = RVi
0 si Vi > 0
5 si Vi < 0
−
+
+12V
-12V
(x=i, )
Rx
RR R
−
+
+12V
-12V
Vi
Vo
Zene
Ro se 5 V
sign =
Zene
4 V
I ansduce
To A/D inpu
To FPGA inpu
Figu e 5: Rec i ica ion ci cui
Figu e 3: P o o ype
Rec i ica ion ci cui is illus a ed in igu e 5.
Once signal acquisi ion has been comple ed and
digi al con e ed, da a is ed in o an Ac el FPGA,
1020B, 509 logic blocks o 547 [3] [4] (93 %) ( igu e
6). The FPGA has been designed wi h Ve ilog [5]
and syn hesized wi h Cadence. Clock and sup-
plies a e aken om PC. F equency clock is 8 MHz
and sampling speed is 250 kHz. So, o each sam-
ple, 32p oduc s o andom s eamsa e compu ed.
In e nally, a andomnumbe gene a o anda32bi
coun e , acco ding o igu e 1, is implemen ed in-
side heFPGA.Thiscoun e canbeei he inc eased
o dec eased, and is eadable om he PC. E e y
ime he PC eads he less signi ican by e o he
coun e , i ese s au oma ically. This unc ionali y
has been included o debugging pu poses.
IV. CALIBRATION
I is necessa y o de ine a calib a ion p oceeding
o he measu emen sys em acco ding o he scale
limi s. Maximum ol age alue is 380 V, and max-
imumcu en alue 7A. Tha means ha he alue
(LA 25-NP)
I in
-
+
I ou
Ri
Vss (-12 V)
Vcc (+12 V)
M
Cu en Vol age
(LV 25-P)
I ou
Vss (-12 V)
Vcc (+12 V)
M
R
V in
+ ΗΤ
− ΗΤ
25 k Ω
Figu e 4: Schema ic diag am o ansduce connec ions
. . .
da a
add esses
clk
ese
Supplies
+5, -5, +12, -12
FPGA
MAXIM
MAXIM
1020BNF
MAX151
MAX151
Figu e 6: Tes boa d
o a coun e uni will be:
1
pul se
=
V
I
8
106
W
s
=
3
:
325
10
,
4
W
s
Maximum coun ing ime is:
T ime
=
232
8
106
=
536
:
87
s
=
8
:
947
min
In wo FPGA’s pins, we ex ac ol age and cu -
en andom pulse s eams, and, wi h a e y sim-
ple ci cui , we eco e analog alue. This ci cui s
consis so alow pass il e [6]. Calib a ion is done
by wo po en iome e s ha modi y ol age and
cu en gain.
A DC powe supply has beenused o modi y ol -
age be ween 0 and 100 V. Fo 100 V and 3.75 A,
analog alue o cu en and ol age has been e-
co e ed a he end o he chain, ha is, a he ou -
pu o FPGA. Po en iome e s has been calib a ed
so ha we ge he equi alen alue o 100 V and
3.75 A a he ou pu o he FPGA. Once calib a ion
is inished, in e medium aluesa e aken ocheck
calib a ion quali y. The esul is illus a ed in ig-
u es 7 and 8. Y axis ep esen s in bo h cases he
mean alue a he ou pu o he low pass il e , as
men ioned abo e.
0.0 50.0 100.0 150.0 200.0 250.0 300.0 350.0 400.0
0.0
50.0
100.0
150.0
200.0
250.0
300.0
350.0
400.0
450.0
500.0
Vol age
Mean alue (mV)
Figu e 7: Vol age calib a ion
0.0 1.0 2.0 3.0 4.0 5.0 6.0 7.0
0.0
100.0
200.0
300.0
400.0
500.0
Cu en (A)
Mean alue (mV)
Figu e 8: Cu en calib a ion
I can be obse ed ha we do no co e he whole
ol age and cu en scale, because ou DC powe
supplyisonlyup o100V.Besides, he eisano se
incu en and ol agecalib a ion ha co esponds
wi h one bi o he analog o digi al con e e .
Con inuous powe measu emen e o , o 2s ime
in e als, is de ailed in igu e 9. I has been ep e-
sen ed ealpowe andexpe imen alpowe agains
ol age.
0.0 100.0 200.0 300.0 400.0
0.0
100.0
200.0
300.0
400.0
ac ual powe
measu ed powe
Figu e 9: Con inuous powe measu emen e o
V. MEASUREMENTS
Measu emen sha e been done using a polyphase
analyze Equa, based on a DSP echnique, as a
e e ence de ice [8]. In e nally, Equa has a 0.2 %
e o in measu emen o ol age and cu en . All
o he magni udes a e compu ed om hese ones.
Re e ence de ice uses he ollowing equa ion o
compu e magni udes:
RMS ol age:
V
L
iN
=
u
u
P
P
k
=
1
2
L
iN
k
P
RMS cu en :
I
L
i
=
u
u
P
P
k
=
1
i
2
L
i
k
P
Ac i e powe :
W
L
i
=
P
P
k
=
1
L
iN
k
i
L
i
k
P
Reac i e powe :
Q
L
i
=
P
P
k
=
1
L
iN
k
i
L
i
(
k
,
)
P
Powe ac o :
PF
L
i
=
W
L
i
p
W
2
L
i
+
Q
2
L
i
whe eP=128,i=1,2,3y
=P/4. I canbeno iced e-
ac i epowe iscompu edusingold cu en alues
ins ead o shi ing ins an aneous cu en alue.
Expe imen al esul s a e sepa a ed om load:
Resis i e powe ac o :
PF EC-RPS Equa E o
1 553.6 557 0.6 %
1 569.4 573.8 0.76 %
1 1088 1104 1.45 %
Capaci i e powe ac o :
PF EC-RPS Equa E o
0.888 439.4 443 0.81 %
0.885 447.5 451 0.77 %
0.693 537 546 1.64 %
Induc i e powe ac o :
PF EC-RPS Equa E o
0.994 536 538.7 0.50 %
0.994 556.8 560.6 0.67 %
0.979 1032 1045 1.24 %
0.979 513.5 519 1.05 %
0.979 524.8 530.6 1.09 %
0.923 900 916.3 1.7 %
0.910 86.81 86.13 0.78 %
0.834 81.88 82.3 0.51 %
Measu es unde 2% e o a e achie ed. Acco d-
ing o [7], his de ice would be a class 2 s a ic
coun e . In u u es imp o emen s, lowe e o
alues a e expec ed. We can men ion, al hough
we ha e no included such esul s, he s abili y o
measu emen s. The s anda d de ia ion o esul s
is e y low.
VI. GENERALIZATIONS
F om he mono phase desc ip ion, i s poly phase
e sioncanbeeasilydeduced. Acco ding o igu e
2, i s gene aliza ion is d awn in igu e 10:
A mul iplexo is u ilized o combine he powe
signal s eams o each phase. Each phase is se-
quen ially selec ed, inc easing o dec easing he
coun e acco ding o signs. The inal esul is a
andom codi ica ion o n- h pa o ins an aneous
poly phase powe a he mul iplexo ou pu , in e-
g a ed in ime by he coun e .
Reac i e powe measu emen is done by in eg a-
ion o eac i e powe . In he mono phase a chi-
ec u e, cu en is he same o he mono phase ci -
cui , bu ol age shi s 90 deg ees espec ol age
o mono phase ci cui ( igu e 12).
U
1
90
o
ADQUISITION
ADQUISITION
STOCHASTIC
CONVERSION
STOCHASTIC
CONVERSION
up/down
CONTADOR
I
1
U
1
’
SHIFTED
SIGNAL
SIGNAL
Figu e 12: Reac i e ene gy compu a ion: mono phase a chi ec u e
Reac i epolyphaseene gywillbe hesumo eac-
i e mono phase eac i e ene gy. Again, he same
mul iplexo s a egy is applied ( igu e 11).
VII. CONCLUSIONS
This pape desc ibes he comple e p oceeding o
design, de elopmen and calib a ion o an elec i-
cal ene gy coun e based on andom signal p o-
cessing. I has been de eloped a FPGA p o o-
ype wi h sa is ac o y esul s. Abo e, i has been
explained all he gene aliza ions o e his simple
p o o ype,sowecanachie e simila u ili iesgi en
by mode ns measu emen equipmen s, based on
DSP. Bu , as a g ea di e ence wi h hese equip-
men s,weha eimp o ed alowcos measu emen
sys em. One o hese equipmen s ha e been used
as a e e ence de ice. A maximum 2 % e o has
been ob ained unde any load condi ion.
As a u u e imp o e, we can hink in an ASIC
implemen a ion. I would be posi i e a mixed
echnology ASIC, including analog o digi al con-
e e s. This way, i would be only necessa y a
p e ious s age o signal acquisi ion be o e ASIC,
educing manu ac u ing cos . This measu emen
p oceeding is pa en pending [9].
REFERENCES
[1] Lah i,Teu o.
Eu opeanpa en applica ion,No.
94110967.0
. ENERMET OY.
[2] W. R. Ge me , M. Negahban-Hagh, M. J. Ouel-
le e, B. Whi e.
Eu opean pa en applica ion,
No. 94203283.0
. SILICON SYSTEMS, INC.
[3]
The
AC T
TM
Family Mac o Lib a y Guide
Ac-
el Co po a ion.
[4]
Field P og ammable Ga e A ay. Applica ion
Handbook
. Texas Ins umen s.
[5]
Ve ilog-XL. Re e ence Manual, ol 1,2,3
. Ca-
dence Design Sys ems,Inc.
[6] J.G. O ega, C.L. Jane , J.M. Que o and L.G.
F anquelo.
“Analog o Digi al and Digi al
o Analog Con e sion Based on S ochas ic
Logic”
. P oceedings IECON’95.
[7]
UNE-EN 61036:1994
. AENOR.
[8]
Elec ic Powe Quali y Analyze
. TeamWa e.
[9] J.M. Que o, S. To al, L.G. F anquelo.
Elec ical
ene gy s a ic coun e based on andom signal
p ocessing. No. 9700600
. Se ille Uni e si y.
SIGNAL
ADQUISITION CONVERSION
STOCHASTIC
SIGNAL
ADQUISITION SIGNAL
ADQUISITION
SIGNAL
ADQUISITION
SIGNAL
ADQUISITION
SIGNAL
ADQUISITION
SIGNAL
ADQUISITION
SIGNAL
ADQUISITION SIGNAL
ADQUISITION
SIGNAL
ADQUISITION
SIGNAL
ADQUISITION
.
.
.
.
.
.
mux
U
I
1
1
U
I
2
2
U
n
n
COUNTER
up/down
I
Figu e 10: poly phase sys em gene aliza ion
SIGNAL
ADQUISITION CONVERSION
STOCHASTIC
SIGNAL
ADQUISITION SIGNAL
ADQUISITION
SIGNAL
ADQUISITION
SIGNAL
ADQUISITION
SIGNAL
ADQUISITION
SIGNAL
ADQUISITION
SIGNAL
ADQUISITION SIGNAL
ADQUISITION
SIGNAL
ADQUISITION
SIGNAL
ADQUISITION
U
1
90
o
90
o
90
o
.
.
.
.
.
.
mux
I
1
I
2
I
n
COUNTER
up/down
2
U
2
’
U
n
’
n
UU
U
1
’
SHIFTED
SHIFTED
SHIFTED
Figu e 11: Reac i e ene gy compu a ion: poly phase a chi ec u e
