Page 433 - Decision Making Applications in Modern Power Systems

Impact of demand-side management system Chapter | 15 393

PV Watt-hours needed per day
PV module size 5 ð15:4Þ
Average sun hours per day in year
Battery capacity: The battery size should be large enough to store the suf-
ficient energy to supply the load in the nonsunny hours and cloudy days.

k a
Battery capacity ðAhÞ 5 3 n au ð15:5Þ
η 3 DOD b 3 V nl
b
where k a is the Watt-hours needed for the appliances per day, η b is the bat-
tery efficiency (0.85), DOD b is the depth of discharge (0.5), V nl is the nomi-
nal voltage of the battery, n au is the number of autonomy (2 days), and

average winter temperature is 80 F.
The size of the BB, PV plant, and the system cost for an autonomous DC
microgrid with the consideration of the different distribution systems can be
found in Table 15.2. In the case of AC distribution system including AC
appliances (ACDSA), the AC technology based appliances are used, which
are less efficient as compared to DC appliances. The DC AC and
AC DC AC converters are used to interconnect the PV plant and BB with
the AC bus, which is the cause of poor efficiency of the system. Therefore
building energy demand with ACDSA is 4.2 kW h, which is the highest one
as compared to the other four cases and 1.5 times higher than the direct cur-
rent distribution system including direct current appliances (DCDSA).

TABLE 15.2 Description of PV plant and battery bank and their cost.
Source/Load ACDSA ACDSD DCDSD DCDSD DSM
Building energy 4.2 3.1 2.7 2.7
demand (kW h)
Battery AH needed per day 910 672 585 434
Number of battery (150 A h) 7 5 4 3
PV plant (kW) 1.590 1.175 1.023 0.7
Number of PV module 16 12 11 7
(100 W)
PV cost (Rupees) 160,000 120,000 110,000 70,000
Battery cost (Rupees) 94,500 67,500 54,000 40,500
System cost (Rupees) 254,500 187,500 164,000 110,500

ACDSA, AC distribution system including AC appliances; ACDSD, AC distribution system
including DC appliances; DCDSD, DC distribution system including DC appliances;
DCDSD DSM, DC distribution system including DC appliances with demand-side management;
PV, photovoltaic.