EXAMPLE 2.15 Assume that a 5-kW air conditioner would run 80% of the time (80% duty cycle) during the peak hour and might be limited by utility remote control to a duty cycle of 65%. Determine the following: (a) The number of minutes of operation denied at the end of I h of control of the unit. (b) The amount of reduced energy consumption during the peak hour if such control is applied simultaneously to 100,000 air conditioners throughout the system. (c) The total amount of reduced energy consumption during the peak. (d) The total amount of additional reduction in energy consumption in part (c) if T&D losses at peak is 8%.

EXAMPLE 2.15
Assume that a 5-kW air conditioner would run 80% of the time (80% duty cycle) during the peak hour
and might be limited by utility remote control to a duty cycle of 65%. Determine the following:
(a) The number of minutes of operation denied at the end of I h of control of the unit.
(b) The amount of reduced energy consumption during the peak hour if such control is applied
simultaneously to 100,000 air conditioners throughout the system.
(c) The total amount of reduced energy consumption during the peak.
(d) The total amount of additional reduction in energy consumption in part (c) if T&D losses
at peak is 8%.
Solution
(a) The amount of operation that is denied is
(0.80 - 0.65) x (60 min/h) = 9 min.
(b) The amount of reduced energy consumption during the peak is
(0.80 - 0.65) x (5 kW) = 0.75 kW
(c) The total amount of energy reduction for 100,000 units is
LlS(t) = Savg x [Duncont(t) - Dcont(t)] x N
= (5 kW) 3[0.80 - 0.65] x 100,000
=75 MW.
(d) The total additional amount of energy reduction due to the reduction in the T&D losses is
(75 MW) x 0.08 = 6 MW
Thus, the overall total reduction is
75MW+6MW=81 MW.
This example shows attractiveness of controlling air conditioners to utility company.

Q) Repeat Example 2.15, assuming that the 30-min monthly maximum demands of customers
A and Bare 27 and 42 kW, respectively. The new monthly energy consumptions by customers
A and Bare 8000 and 9000 kWh, respectively. The new lagging load PFs of A and Bare
0.90 and 0.70, respectively.