Page 446 - Decision Making Applications in Modern Power Systems

Impact of demand-side management system Chapter | 15 405

Similarly, at time instant 07:00 hours the washing machine is switched
“ON” with the conventional scheme and remains “ON” during
07:00 08:30 hours time interval as shown in Fig. 15.8B by a red line,
which is the cause to achieve lower SOC than the desired SOC with a
conventional scheme during 07:00 08:30 hours time interval as shown in
Fig. 15.7, while the washing machine task completion time instant is
12:30 hours with 90 minutes operating time. The DSM scheme keeps the
washing machine at the second priority and shifts the washing machine
operating time from 07:00 08:30 hours to the future. As the PV genera-
tion at 10:41 hours becomes higher than the building demand (critical
load and deferrable load washing machine), the washing machine is
switched “ON.” At time instant 10:59 hours the PV generation becomes
lower than the building demand (critical load and deferrable load like
washing machine) and remains lower up to 11:04 hours, so that the wash-
ing machine remains switched “OFF” during 10:59 11:04 hours time
interval while the battery is charged by the surplus power to achieve the
SOC higher than the desired. As the washing machine operation time is
90 minutes, and it runs only for 18 minutes, it has to be switched “ON”
again to complete its task. As the PV generation becomes higher than the
building demand at time instant 11:05 hours, the washing machine is
switched “ON” and remains switched “ON” to 12:18 hours to complete
the task as shown in Fig. 15.9B by a blue line.

Mode III: PV with low SOC of BB (control of noncritical and cycle-
based load): During 12:16 17:40 hours time interval the PV generation
is greater than the building demand but the battery SOC is lower than the
desired with the conventional scheme. The DSM scheme reduces the
building demand by switching “OFF” the controllable loads (LED bulbs
mounted in bedroom-1, bedroom-2, living room, and kitchen as shown in

Conventional scheme
Proposed DSM scheme
1
(A)
0
Control signal 1 0 (B)

1
(C)
0
0000 0400 0800 1200 1600 2000 2400
Time (h)
FIGURE 15.9 Control signal for cycle-based loads and deferrable loads (A) refrigerator, (B)
washing machine, and (C) water pump.