Page 440 - Decision Making Applications in Modern Power Systems

Impact of demand-side management system Chapter | 15 399

while the green push button is used to switch “ON/OFF” the supply of the
main board. The microcontroller executes the control algorithm and creates
the digital control signal in the form of “0” and “1” to actuate the relays to
switch “ON”/“OFF” their respective appliances. The real-time clock gives an
accurate measure of the current time in the circuit as the Arduino mega
board itself does not have a time clock. The values extracted from this circuit
are used to put a time stamp on the recorded data on the SD card. The cur-
rent and voltage sensors are mounted on the board-2 and board-3 to measure
the current for the load, PV plant, and ES and their bus voltage. The data
logging algorithm automatically created a new file with a date stamp and
stored the current and voltage for each minute in a single row of the text file
delimited by a space. The 16 relays are mounted on the board-4, which auto-
matically switch “ON/OFF” the appliances as per the control action gener-
ated by the Arduino Mega based on the control algorithm. The push buttons
and LCD displays are mounted on the board-5. One of the push buttons is
used to start and stop the data logging process, while another is used to con-
vert the relay operations from automatic to manual mode. The display-1 is
used to display the measured current and voltage of PV plant and load, while
the measured SOC, current, and voltage of the battery (i.e., ES) are displayed
on the display-2.

15.5 Demand-side management algorithm
The flowchart of the control algorithm for the DSM scheme is shown in
Fig. 15.4. The PV plant feed their generated power to the DC microgrid irre-
spective of the building demand at different time instants. The smart sensors
are mounted at service mains of the load, PV plant, and BB to monitoring
the power of PV plant, load, and ES in real time. The control objective of
the DSM scheme is to maximize the direct use of the PV power in the build-
ing and maintain the desired SOC of the ES to supply the future load of the
building. Therefore the DSM scheme schedules the deferrable loads (i.e.,
washing machine and pump) during the regular sunny hours (i.e., when the
PV generation is higher than the critical load of the building) without affect-
ing the comfort of the consumer. In this way the DSM scheme maximizes
the direct use of power generation of PV plant. This approach reduces the
charging/discharging cycles of the battery (i.e., power losses in the BB) and
improves the efficiency of the DC microgrid. The controllable loads such as
DC tube lights are switched “OFF,” and the refrigerator operates with the
“control cycle” mode to reduce the building demand and increase the charg-
ing or decrease the discharging of the BB to achieve the desired SOC as
soon as possible.
The desired SOC shows the minimum requirement of stored energy in
the battery to supply the future load during the time interval in which the PV
plant does not generate any power (i.e., nighttime) or produces a small