Mecc Alte DER1 - Page 22

DER1 digital regulator instruction manual - rev. 05 - pag. 23
If the STAB trimmer is enabled (STAB Flag Trimmer present) its angular position, available at location
L[33], is transformed by the Fc
STAB
(2)
function into the numeric value available at location L[53]
(3)
(figs. 8a
and 8b). If the STAB trimmer is disabled, the value of location L[53]
(3)
directly becomes the value set using
the P[20] parameter (fig. 8c).
The proportional gain K
P
is obtained by multiplying the value of location L[53]
(3)
by a coefficient that de-
pends on the value given in parameter P[11]
(4)
.
NOTE
(1)
Starting from Rev. 15 of the firmware
NOTE
(2)
The Fc
STAB
, Fcig
50
and Fcig
60
functions are not implemented in the DER1s with firmware up to version 14, and in the
block diagram they are considered as identities, i.e. L[53]
(3)
=Fc
STAB
(L[33])=L[33] e Fcig
60
(L[53] ) = Fcig
50
(L[53])=L[53]
(3)
.
With these regulators the STAB trimmer needs to be rotated by less than two notches counted clockwise.
NOTE
(3)
Location available to the user from firmware Rev. 15.
NOTE
(4)
Structure valid also for DER1s with firmware up to version 14 but without location L[53] and L[54] availability
Trimmer
STAB
L
[33] L[53]
2
P
[11]
K
P
2
P[12]
K
I
P
[13]
L
[54]
Fc
STAB
()
fig. 8b: drawing of the numeric elaboration of the proportional and integral
gain by a DER1/A with the STAB trimmer enabled
The integral gain, available at location L[54]
(3)
minus the multiplication by a coefficient, depends on the va-
lue of the proportional gain at location L[53]
(3)
; in the standard DER1 (grey box) with the STAB trimmer
enabled (STAB Flag Trimmer present) the value of location L[53]
(3)
at 50Hz is transformed by the function
Fcig
50
(2)
and by the multiplication of the value of parameter P[13], in the numeric value available at location
L[54]
(3)
; at 60Hz the transformation function is Fcig
60
(2)
, different from that at 50Hz, (fig. 8a); in the other
versions of the DER1 (fig. 8b), for example DER1/A (blue box), or if the STAB trimmer is disabled
(4)
(fig.
8c), not only is there a difference between the integral value at 50Hz and at 60Hz, but even the value of
location L[54]
(3)
is obtained by simply multiplying the proportional gain at location L[53]
(3)
by the value of
parameter P[13].
L
[53]
2
P[11]
K
P
2
P[12]
K
I
P
[13]
L
[54]
P[20]
fig. 8c: drawing of the numeric elaborations of proportional and integral gain by all
DER1 with STAB trimmer disabled
In both cases, the effective integral gain K
I
is obtained by multiplying the value of location L[54]
(3)
by a co-
efficient that depends on the value given in parameter P[12]
(4)
.
The mentioned coefficients can take on values of 1, 2, 4, 8, 16, 32 or 64 according to the values written in
parameters P[11] (for proportional gain) and P[12] (for integral gain); these values represent the value as-
signed to base 2 (fixed) to obtain the required coefficient (e.g. parameter P[11] = 4 => multiplication coeffi-
cient of the proportional gain = 2
4
= 16, P[12] = 3 => multiplication coefficient of the integral gain = 2
3
= 8).
The following tables show, for every three-phase machine on 50Hz and 60Hz, the STAB trimmer calibra-
tion which allows increased speed of response to the transistor with the generator in stand-alone opera-
tion. In case of different applications (for example alternators reconnected in single-phase, in parallel
among them or in parallel with the grid, with motors having less than 4 cylinders and so on) it may be nec-
essary to readjust the STAB trimmer calibration.
If the voltage cannot be stably adjusted for permanent operation and/or in the transient by the STAB trim-
mer settings, it may be necessary to vary one or more stability adjustment parameters: P[11], P[12] and P
[13] the description of which is given in table 6.