Classification of Hydro Power Plants According to Nature of Load
According to nature of load, the plants are classified as follows :
(i) Base load plants, (ii) Peak load plants, (iii) Pumped storage plants for peak-loads.
(i) Base load plants : These are the plants which operate to supply the load on the base portion of the load curve. The load on such plants is practically constant. They are generally of large capacity. The load factor is high. Hydro plants which have large storage capacity are most suitable as base-load plants. Run-off river plants without pondage can also be used as base-load plants.
(ii) Peak load plants : Run-off river plants with pondage can be used as peak load plants. Depending upon the reservoir, the plant can supply the load. If the pondage is enough, it can supply a large portion of the load, Reservoir plants with sufficient storage or large catchment area can be used as base-load or peak load plants as required.
(iii) Pumped storage plants : Such type of plant is as shown in Figure. They are used when the available quantity of water for generation is insufficient. Generally, a storage pond is built to store water at head race and tall race. The water passing through the turbines is stored in tall race pond and it is pumped back by the generating system working as a motor and stored in the head-race pond again, during the off peak-load hours of the system. Water is drawn from the pond through the penstock to operate the turbine. These type of plant can be operated only in interconnected systems.
