The load on any power plant can be considered into two parts namely
- Base Load Plants
- Peak Load Plants
Load
in a power system varies all the day. Electrical power generated by the
generating stations depends on the demand for electrical power. During
day time demand for electricity will be more and hence all the
generating units will be running under full load. During nights, load on
the generating stations will be less. The unvarying load which occurs
almost the whole day on the power plant is called the base load. Whereas the various peak demands of the load over and above the base load of the power plant is called peak load.
If
the load represented in the figure is to be supplied by the single
power plant only, the installed capacity of the plant should be equal to
the peak load demand or more. Such a power plant is uneconomical since
the peak load occurs only for a short duration in a day or in an year.
Hence such a peak load should not be supplied from a single power plant.
Therefore there should be an optimum mix of the power plants which
supply the base load round the year and some other power plants of
different type supply power to the peak load plants. Thus the
co-ordination of operation of different power stations is essential.
Base Load Power Plants:
The power plants to be employed as base load plants should have some of the characteristics:
- Low operating cost
- Capability of operating for longer periods
- Maintenance should be simpler and requires less time. Time duration between the maintenance should be long
- Requires few operating personnel
Peak Load Power Plants
The power plants to be employed as peak load plants should have the following capabilites:
- Quick start
- Faster synchronization to the grid
- Should be faster in taking up the system loads
- Quick response to the load variations
Hydro Power Plants both Base Load and Peak Load Plants:
The
hydro-power plants are well suited for both base load as well as peak
load operational plants. The hydro power plants should be employed for
base load operations as far as possible because of their higher capital
cost. However during the period of draught or in summer season, the
hydro power plants may be used as a peak load power plants
Steam power plants
or thermal power plants gives minimum cost of generation per unit when
employed as base load plant. However, in order to save the fuel it may
be used to run as peak load plants in some circumstances
Nuclear power plants are suitable only for base load operation. Nuclear power plants have the highest load factor of over 0.8 to 0.9
Gas turbine power plants are best suited for peak load power plant operations
Diesel engine power plants
are generally will have higher operational costs and is uneconomical to
operate them continuously. Diesel plants are mostly operated as peak
load plants
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