Thermal Power Station

1. ELECTRICAL POWER
GENERATION
Load curve and Important terms
By D. N. Thakkar
RCTI, Ahmedabad

2. Connected load
• The sum of continuous ratings of all the
electrical equipments connected to the supply
system is called the connected load

3. Demand Factor.
• The word “demand” itself says the meaning of
Demand Factor. Demand Factor = Maximum
demand / Total connected load
• For example, an over sized motor 20 Kw drives a
constant 15 Kw load whenever it is ON. The
motor demand factor is then 15/20 =0.75= 75 %.
• Demand Factor is express as a percentage (%) or
in a ratio
• Demand factor is always < =1.
• The lower the demand factor, the less system
capacity required to serve the connected load.

4. Load factor
• Load Factor = Actual Load / Full Load
• OR
• Load Factor = Area under the curve / Area of
the rectangle
• OR
• Load Factor = Units generated / (Maximum
demand x hours)

5. Load factor
• It is the ratio of actual kilowatt-Hours used in
a given period, divided by the total possible
kilowatt -hours that could have been used in
the same period at the peak KW level.
• Load Factor = ( energy (kWh per month) ) /
( peak demand (kW) x hours/month )
• The Load factor is always <=1.

6. Load factor
• Higher the load factor is GOOD and it will more
Output of Plan, lesser the cost per unit which
means an electricity generator can sell more
electricity at a higher spark spread, Fixed costs
are spread over more kWh of output. A power
plant may be highly efficient at High load factors.
• Low load factor is a BED. A low load factor will
use electricity inefficiently relative to what we
could be if we were controlling our peak demand.
A power plant may be less efficient at low load
factors.

7. Connected load factor
Connected load factor = Average load /
connected load
= (Average demand / Maximum demand) x
(Maximum demand / connected load)
= Load factor x Demand factor

8. Diversity factor
• Diversity Factor = Sum of Individual
Maximum Demands / Maximum Demand of
the System.
• The diversity factor is always >= 1.

9. Coincidence factor
• The reciprocal of diversity factor is
coincidence factor
• Coincidence factor = Maximum demand /
Sum of individual maximum demands
• The Coincidence Factor is always <=1.

10. Load diversity
• Load diversity is the difference of sum of
individual maximum demands of two or more
consumers and their combined maximum
demand

11. Loss factor
Loss factor = Average power loss / Power loss at
peak load

12. Plant capacity factor
Plant capacity factor = Average demand /
Installed plant capacity
OR
Plant capacity factor = Units generated in a year
/ Installed plant capacity x 8760

13. Utilization factor
Utilization factor = Maximum demand / Plant
capacity

14. Plant use factor
Plant use factor = Units generated / ∑kWh
= Units generated / kW1h1+kW2h2+….

15. Load curve
Load curve is the variation
of load with time on a
Power Station. As the load
on a Power Station never
remain constant rather it
varies time to time, these
variations in load is plotted
on half hourly or hourly
basis for the whole day. The
curve thus obtained is
known as Daily Load Curve.

16. Importance of Load Curve
• From the daily load curve we can have insight of load at different time for a
day.
• The area under the daily load curve gives the total units of electric energy
generated.
• Units Generated / day = Area under the daily Load Curve in kW
• The peak point on the daily load curve gives the highest demand on the
Power Station for that day.
• The average load per day on the Power Station can be calculated using the
daily load curve.
• Average load = Area under the daily Load Curve (kWh)/ 24 hrs.
• Load curve helps in deciding the size and number of Generating Units.
• Load Factor = Avg. Load / maximum Load = Avg. Load x24 / 24xmaximum
Load
• = Area under daily Load Curve/Area of Rectangle having Daily
Load Curve
• Load curve helps in the preparing the operation schedule of the generating
units.

17. Load Duration Curve
• Load Duration Curve is the plot of Load versus
time duration for which that load was
persisting.

18. Base load & Peak load
• Base load is the minimum level of electricity
demand required over a period of 24 hours. It
is needed to provide power to components
that keep running at all times (also referred as
continuous load). Peak load is the time of
high demand.

19. Base load & Peak load

20. Base load & Peak load

21. Characteristics of Base load station
• Operating throughout the year
• Load factor is high
• Efficiency is high
• Cost of unit generation is less
• Capital cost is high
• Capacity is high
• Difficult to start and stop

22. TPS in Gujarat