Civil Engineering Reference
In-Depth Information
Fig. 5.22
Scheme of the fancoil unit
air temperature,
T
a
imp
, by the regulation of the water flow through it,
q
W
, and/or
the return air velocity,
v
a
ret
,are
controlled by means of the aperture of a valve,
Ap
Va l ve
, and the fan velocity,
V
Fan
,
respectively. Hence, the fancoil unit can be classified as Multiple Inputs Single Out-
put (MISO) system where the control inputs are the aperture of a valve,
Ap
Va l ve
, and
the fan velocity,
V
Fan
, and the output is the impulse air temperature,
T
a
imp
. Therefore,
it is necessary to develop a fancoil MISO controller capable of achieving the impulse
air temperature setpoint provided by the PNMPC. More specifically, a discrete PI
with anti-windup combined with a split-range control strategy has been used, as
illustrated in Fig.
5.21
. Furthermore, as the solar cooling installation that is available
inside the building has two operation modes, winter and summer (Pasamontes et al.
2009
), it is necessary to design different controllers for each of them.
v
a
ret
. At the same time, these two variables,
q
W
and
5.4.2.1 PI with Anti-Reset Windup Function
This controller receives as input the impulse air temperature setpoint estimated by
means of the PNMPC optimizer. It consists of a discrete time PI controller with a
sample time of
t
s
=
8 s, which is designed to obtain the impulse air temperature based
on the upper layer reference as a function of a global control signal,
u
, comprised
between 0 and 100%. More specifically, two different PI controllers have been tuned
(one for each operation mode, winter or summer). To tune the parameters of each one
of the PI controllers, a first order function which relates changes in the impulse air
temperature with the combined effect of water flow and the fancoil velocity has been
obtained. This function has been estimated through a real test, in which, a step from
an initial fancoil state equal to 0% (defined by both a fancoil velocity, and an aperture
of the valve equal to 0%) to a final fancoil state equal to 100% (defined by both a
fancoil velocity, and an aperture of the valve equal to 100%) has been performed.
Hence, the transfer functions for both operation modes which represent the relation
