Power Generation Economics : Concepts

Introduction to Economics of Power Generation:

The function of a power station is to deliver power at the lowest possible cost per kilo watt hour. This total cost is made up of fixed charges consisting of interest on the capital, taxes, insurance, depreciation and salary of managerial staff, the operating expenses such as cost of fuels, water, oil, labor, repairs and maintenance etc.

The cost of power generation can be minimized by :

1. Choosing equipment that is available for operation during the largest possible % of time in a year.
2. Reducing the amount of investment in the plant.
3. Operation through fewer men.
4. Having uniform design
5. Selecting the station as to reduce cost of fuel, labor, etc.

All the electrical energy generated in a power station must be consumed immediately as it cannot be stored. So the electrical energy generated in a power station must be regulated according to the demand. The demand of electrical energy or load will also vary with the time and a power station must be capable of meeting the maximum load at any time. Certain definitions related to power station practice are given below:

Load curve :

Load curve is plot of load in kilowatts versus time usually for a day or a year.

Load duration curve :

Load duration curve is the plot of load in kilowatts versus time duration for which it occurs.

Maximum demand :

Maximum demand is the greatest of all demands which have occurred during a given period of time.

Average load :

Average load is is the average load on the power station in a given period (day/month or year)

Base load :

Base load is the minimum load over a given period of time.

Connected load :

Connected load of a system is the sum of the continuous ratings of the load consuming apparatus connected to the system.

Peak load :

Peak load is the maximum load consumed or produced by a unit or group of units in a stated period of time. It may be the maximum instantaneous load or the maximum average load over a designated interval of time.

Demand factor :

Demand factor is the ratio of maximum demand to the connected load of a consumer.

Diversity factor :

Diversity factor is the ratio of sum of individual maximum demands to the combined maximum demand on power stations

Load factor :

Load factor is the ratio of average load during a specified period to the maximum load occurring during the period.

Load factor = Average Load / Maximum demand

Station load factor :

Station load factor is the ratio of net power generated to the net maximum demand on a power station.

Plant factor :

Plant factor is the ratio of the average load on the plant for the period of time considered, to the aggregate rating of the generating equipment installed in the plant.

Capacity factor :

Capacity factor is the ratio of the average load on the machine for a period of time considered, to the rating of the machine.

Demand factor :

Demand factor is the ratio of maximum demand of system or part of system, to the total connected load of the system, or part of system, under consideration.

Utilization factor :

Utilization factor is the ratio of maximum demand of a system or part of the system, to the rated capacity of the system, or part of the system, under consideration.

Firm power :

Firm power is the power intended always to be available even under emergency conditions.

Prime power :

Prime power is the maximum potential power constantly available for transformation into electrical power.

Cold reserve :

Cold reserve is the reserve generating capacity that is available for service but not in operation.

Hot reserve :

Hot reverse is the reserve generating capacity that is in operation but not in service.

Spinning reserve :

Spinning reserve is the reserve generating capacity that is connected to the bus and ready to take load.

Run of river station :

Run of river station is a hydro-electric station that utilizes the stream flow without water storage.

Base Load supply :

In inter connected systems with many generating stations of various types, the choice of station to supply the varying load is of considerable economic significance. Entire load of the system may be divided into two parts e.g., base load and peak load. Base load is the load which is supplied for most of the time which remains more or less constant. Peak load is the intermittent requirement at particular hours of the day and so on.

The main consideration for base load provision are :

(i) high efficiency
(ii) high availability of the system.

Even a higher capital cost is sometime favored if it can ensure resultant gain in efficiency, as the cost is spread over a large total energy value.

Nuclear power plants are invariably used as base load plants. Thermal power plants and hydroelectric power plants can also be used as base load plants.

As far as peak load plants are concerned, these plants should have :

(i) ability to start and take full load with a short time
(ii) low capacity cost in view of the small annual output with the efficiency only a secondary condition.

Obsolete steam plant, through less efficient can't be used to met with peak load demand. Gas turbines, diesel engine plant and pumped storage stations are also suitable for peak load operation.

Peak Load :

Load on a power plant seldom remain constant. The load varies from season to season and also in a day from hour to hour. In summer, due to fans and air conditioners the plants have generally high load as compared to winter months. During day time also lights are switched on in the evening , the load on the plant will increase. During the days of festivals like national festivals, national days etc., there is excessive demand of electrical power. A power generating plant has to meet with all such variable demand sand at the same time maintain over all economy of operation. The period during which the demands on a power station is highest is known as peak load. Peak load on a plant may exist for small duration but still the plant has to devise ways and means for meeting with such demands.

from ur's -- Bellapuri saikumar
( www.facebook.com/saikumar544)

Monday, 15 June 2015