Construction and working principle of pumped storage plants

Construction and working principle of pumped storage plants

Figure: Pumped storage plant.

Pumped storage plants are employed at the places where the quantity of water available for power generation is inadequate. Here the water passing through the turbines is store in ‘tail race pond’During. low load periods this water is pumped back to the head reservoir using the extra energy available. This water can be again used for generating power during peak load periods. Pumping of water may be done seasonally or daily depending upon the conditions of the site and the nature of the load on the plant.

Such plants are usually interconnected with steam or diesel engine pants so that off peak capacity of interconnecting stations is used in pumping water and the same is used during peak load periods. Of course, the energy available from the quantity of water pumped water the power available is reduced on account of losses occurring in prime movers.

Advantages:

The pump storage plants entail the following advantages :

1.    There is substantial increase in peak load capacity of the plant at comparatively low capital cost.

2.    Due to load comparable to rated load on the plant, the operating efficiency of the plant is high.

3.    There is an improvement in the load factor of the plant.

4.    The energy available during peak load periods is higher than that of during off peak periods so that inspite of losses incurred in pumping there is over-all gain.

5.    Load on the hydro-electric plant remains uniform.

6.    The hydro-electric plant becomes partly independent of the stream flow conditions.

Under pump storage projects almost 70 percent power used in pumping the water can be recovered. In this field the use of ‚Reversible Turbine Pump‛units is also worth noting. These units can be used as turbine while generating power and as pump while pumping water to storage. The generator in this case works as motor during reverse operation. The efficiency in such case is high and almost the same in both the operations. With the use of reversible turbine pump sets, additional capital investment on pump and its motor can be saved and the scheme can be worked more economically.

Pumped storage plants are employed at the places where the quantity of water available for power generation is inadequate. Here the water passing through the turbines is store in ‘tail race pond’During. low load periods this water is pumped back to the head reservoir using the extra energy available. This water can be again used for generating power during peak load periods. Pumping of water may be done seasonally or daily depending upon the conditions of the site and the nature of the load on the plant.