ade7880 Analog Devices, Inc., ade7880 Datasheet - Page 55

• Manufacturer Part Number: ade7880
• Description: Polyphase Multifunction Energy Metering Ic With Harmonic Monitoring
• Manufacturer: Analog Devices, Inc.

Preliminary Technical Data
When the neutral current and the sum of the three phase
currents represented by ISUM register are analyzed, the
following metering quantities are computed for both currents:
-rms of fundamental and of up to 2 harmonics or rms of up to 3
harmonics: I
-harmonic distortions of the analyzed harmonics.
Configuring the harmonic calculations
The ADE7880 requires a time base provided by a phase voltage.
Bits 9 and 8 (ACTPHSEL) of HCONFIG[15:0]register select
this phase voltage. If ACTPHSEL =00, the phase A is used. If
ACTPHSEL =01, the phase B is used and if ACTPHSEL=10, the
phase C is used. If the phase voltage used as time base is down,
simply select another phase and the harmonic engine will
continue to work properly.
The phase under analysis is selected by bits 2 and 1 (HPHASE)
of HCONFIG[7:0]register. If HPHASE=00, the phase A is
monitored. If HPHASE=01, the phase B is monitored and if
HPHASE=10, the phase C is monitored. If HPHASE=11, the
neutral current together with the sum of the phase currents
represented by ISUM register are monitored.
Harmonic calculations when a phase is monitored
As mentioned, when a phase is monitored, fundamental
information together with information about up to 3 harmonics
is computed. The indexes of the 3 additional harmonics
simultaneously monitored by the ADE7880 are provided by the
8-bit registers HX, HY and HZ. Simply write the index of the
Table 20. Harmonic engine outputs when phase A, B or C is analyzed and the registers where the values are stored
Quantity
Rms of the fundamental component
Rms of a harmonic component
Active Power of the fundamental component
Active Power of a harmonic component
Reactive Power of the fundamental component
Reactive Power of a harmonic component
x
, I
y
, I
z
, x,y,z=1,2, 3,…, N.
Definition
V
V
V
V
Q
Q
Q
P
P
P
P
1
x
y
z
1
x
z
y
1
, I
x
y
, I
, I
, I
=
=
=
=
=
=
=
1
x
y
, y = 2, 3,…, N
z
, x = 2, 3,…, N
V
V
V
V
, z = 2, 3,…, N
V
V
V
1
x
z
1
y
x
y
I
I
I
I
Rev. PrE | Page 55 of 103
I
I
1
I
1
x
z
y
x
cos
y
sin
cos
cos
cos
sin
sin
(
(
(
(
(
ϕ
ϕ
ϕ
(
ϕ
ϕ
(
ϕ
ϕ
1
1
x
z
x
y
y
−
−
−
−
−
−
−
γ
γ
γ
γ
γ
γ
γ
1
1
x
z
x
)
)
y
y
)
)
)
harmonic into the register for that harmonic to be monitored. If
the second harmonic is monitored, write 2. If harmonic 51 is
desired, write 51. The fundamental components are always
monitored, independent of the values written into HX, HY or
HZ. Therefore, if one of these registers is made equal to 1, the
ADE7880 monitors the fundamental components multiple
times. The maximum index allowed in HX, HY and HZ
registers is 63. The no attenuation pass band is 2.8KHz,
corresponding to a -3dB bandwidth of 3.3KHz, thus all
harmonics of frequency lower than 2800Hz are supported
without attenuation.
The rms of the phase voltage and phase current fundamental
components are stored into FVRMS and FIRMS 24-bit signed
registers. The associated data path is presented in Figure 58.
Similar to the rms current and voltage rms data paths presented
in Root Mean Square Measurement section, the data path
contains 24-bit signed offset compensation registers xIRMSOS,
xVRMSOS, x=A, B, C for each phase quantity. The rms of the
phase current and phase voltage 3 harmonic components are
stored into HXVRMS, HXIRMS, HYVRMS, HYIRMS,
HZVRMS and HZIRMS 24-bit signed registers. The associated
data path is presented in Figure 59 and contains the following
24-bit signed offset compensation registers: HXIRMSOS,
HYIRMSOS, HZIRMSOS, HXVRMSOS, HYVRMSOS and
HZVRMSOS.
It is recommended to leave the offset compensation registers at
0, the default value.
)
)
, x = 2, 3,…, N
, z = 2, 3,…, N
, x = 2, 3,…, N
, y = 2, 3,…, N
, y = 2, 3,…, N
ADE7880 register
FVRMS, FIRMS
HXVRMS, HXIRMS
HYVRMS, HYIRMS
HZVRMS, HZIRMS
FWATT
HXWATT
HYWATT
HZWATT
FVAR
HXVAR
HYVAR
ADE7880