Dr. RIYADH S. AL-TURAIHI
POWER PLANT
LEC.NO.(2)
____________________________________________________________________
Load Variation:
What happens when load change on station ,say at particular point or
instant the plant carries a steady load and energy input balances plant
output of losses ,suddenly many lights are switched on the effect will be
as follows:
1- This reduces over all resistance of the system and a greater current
flows through the generator armature and connected circuit .
2- Reduces the turbine generated shaft speed.
3- Bring governor in to action which will open the throttle valve more for
supplying more steam.
4-Reduction of steam pressure in the boiler .
5-Will give single to automatic combustion control system to speed up
the forced draft and induced draft fan and also the fuel feed and water
feed system.
6-Governnor spring tension helps in opening the throttle valve ,increase
the flow of steam bring the shaft speed normal .The total time takes in
this process from few second to few minutes.
Dr. RIYADH S. AL-TURAIHI
POWER PLANT
LEC.NO.(2)
____________________________________________________________________
Distribution of Electricity:
Demand Factor:
demand factor=Maximum demand / connected load
is the ratio of the maximum demand of a system or part of the a system to
the total connected load of the system under consideration .
Diversity factor:
DF=
is the ratio of the sum of the individual max demand of the various sub
division of a system or part of a system to the max demand of the hole
system or part of the system under consideration the partial subdivision
may be one substation where there are several in a system or may be a
group of residential customs .Supplied by one Transformer.
Load factor=
Dr. RIYADH S. AL-TURAIHI
POWER PLANT
LEC.NO.(2)
____________________________________________________________________
Average load=
capacity factor=
when applied to machine or equipment ,rating of the machine is capacity.
when applied to power plant ,plant capacity is the capacity.
Use Factor=
=
Ex(1):Given (70 Mw) power plant ( installed capacity ),Annual
output=250,000,000 kw/h, having peak head=56700 kw,plant was not
use for (500 hr) in one year, find the load factor ,capacity factor and
use factor?
Ex(2):Given :capacity (70 Mw),straight line (load variation
curve)varies, from (50 Mw to 6 Mw) ,find load factor ,capacity
factor and demand factor?
Ex(3):Given: L.F=0.5,CF=0.3,use factor=0.37,Reverse of low peak
load=20000 kw, find capacity and peak load? if capacity=Lp+
Reverse
Dr. RIYADH S. AL-TURAIHI
POWER PLANT
LEC.NO.(2)
____________________________________________________________________
Plant location:
1- Transmission of energy.
2- Supply of fuel (transportation).
3- Supply of water.
4- Availability of land and its cost.
Station performance of operation characteristics.
I=input in million of kg/hr
L=output in kws of mega watts
Io=amount of energy required to keep the plant functioning (frictional of
other losses).
y=a+bx+cx2+dx3+………
I=a+bL+cL2+dL3+………
dI/dL=increment rate
Heat rate= I/L (kJ/hr.kw)
=
Dr. RIYADH S. AL-TURAIHI
POWER PLANT
LEC.NO.(2)
____________________________________________________________________
= +b+cL+dL2
increase rate=dI/dL= 0+b+2cL+3dL2
Average heat rate=
Ex(4):A 20 Mw station has an input -output curve defined by:
I= 30+0.5L0.65L2+0.01L3
where I t is the in millions of kg/hr and L is in (Mw) ,find the increase
output from (7Mw) to (9 Mw) by means of the input-output curve
and also by the incremental rate curve?
EX(5): The input -output curve of a (20Mw) generating station in
defined by I= 30+0.5L0.65L2, where I is in millions of ( kJ/hr) and L
is in (Mw) ,find the average heat rate of this station for a day when it
was operating at load of (20Mw) for 12 hr ,and at (4 Mw )load for
the remaining 12 hr?