What are the effects of Variable Load on Power Stations?

Variable Load on Power Station

The load on an electric power system changes from time to time due to uncertain demands of the consumers, this variation in load of a power station is termed as variable load on power station.

An electric power station is designed to meet the load requirements of the consumers. From the standpoint of equipment needed and operating routine, an ideal load on a power station would be of constant magnitude and of steady duration.

However, in actual practice, such a steady load on the power station cannot be realised. It is because the consumers require different blocks of power in accordance with the demands of their activities. Therefore, the load demand of one consumer at any time may be different from that of the other consumer. Consequently, the load on a power station varies from time to time.

Effects of Variable Load on Power Station

The variable load on an electric power station introduces many obstacles in its operation. Some of the important effects of load variation on a power station are as follows −

Requirement of Additional Equipment

The variable load on a power station necessitates to have additional equipment for proper operation of the station.

  • For example, consider a thermal power station. Coal, air and water are the raw materials for the power generation from this station.

  • But in order to produce variable power to meet the load demand, the supply of these materials will be required to be varied correspondingly.

  • If the load demand on the power station is increased, it must be followed by the increased supply of coal, air and water to the boiler in order to meet the increased load demand. Thus, to accomplish this job, additional equipment are required.

In modern power stations, various equipment are used to adjust the supply of raw materials in accordance with the power demand made on the power station.

High Production Cost

The cost of production of electrical energy is increased by the variable load on the power station

An alternator (or electric generator) operates at maximum efficiency near its rated capacity. If a single alternator is used in the power station, then it will have poor efficiency during the periods of light loads on the station. Therefore, in actual practice, a number of alternators of different capacities are installed so that most of the alternators can be operated at almost full-load capacity.

The use of a large number of generating units increases the capital cost per kW of the power plant capacity as well as floor area required. This also increases the cost of production of electrical energy.