There are various classifications of hydroelectric power plants. Based on the nature of load there are two types of hydroelectric power plants: base load type and peak load type.
In the series of articles on the classification the hydroelectric power plants, in this article classification of hydroelectric power plants based on the nature of load have been described. The hydroelectric power plants can be started and stopped easily thus they can be used as per the requirement of the power in the national grid. The starting and stopping procedure of the thermal and nuclear power plants is very lengthy so they cannot be started and stopped frequently and at a short notice, thus they are used for continuous production of power. The hydroelectric power plants can be used for continuous as well as intermittent supply of power whenever required.
Depending on the nature of load on the hydroelectric power plant there are two types of hydroelectric power plants, these are:
1) Base load hydroelectric power plants
The base load type of hydroelectric power plants produce power constantly irrespective of the total load in the national grid. They keep on producing power throughout the day and during all the times of the year. They will stop producing power only during breakdown maintenance. Usually these types of hydroelectric power plants have standby power generation unit to ensure continuous production of power even in case of failure of one of the power generation unit. The generation of power from base load power plants is cheaper so they can be run continuously.
The total power generated within the national grid includes the power generated by the base load type of hydroelectric power plant. The power output from the base load plants is constant and it does not usually vary in the normal working conditions. The total capacity of the national grid includes the power produced by the base power plant. The majority of the power in the national grid it supplied by the base power plants.
All the base plants within the national grid are allotted specific amount of base-load to handle constantly depending upon their power generation capacity. If there are fluctuations or peak demands like during the nighttime, these are handled by the other smaller plants that can be started and stopped easily. The thermal and nuclear power plants are the base plants, but there are many hydroelectric plants that can are being used as the base load power plants.
2) Peak load hydroelectric power plants
Most of the normal power requirements are fulfilled by the base load hydroelectric power plants. However, during night times the requirement of power becomes very high; it is called peak load period. During peak load periods small power plants are started that add to the total power generated in the grid by base load plants. The peak load plants are not run continuously since the cost of production of power from them is high. The hydroelectric power plants can be used as the peak load plants since they can be started and stopped easily. The diesel power plants are also used as the peak load plants since they can be started and stopped easily, but their operation is very expensive.