Hydro Power Plant | Construction and Working
The kinetic energy developed in a hydro power plant due to gravity in a falling water from higher to lower head is used to rotate a turbine to produce electricity. When it falls to the lower water level, the potential energy stored in the water at the upper water level will release as kinetic energy. This turbine rotates when the turbine blades are hit by the following water.
In hilly regions, a water hydro power plant is usually built to obtain a head difference. An artificial dam is built in the way of the river in hilly regions to generate the required water head. Water from this dam is permitted to drop downstream to turbine blades in a controlled manner. As a result, due to the water force applied to its blades, the turbine rotates and therefore the alternator rotates as the turbine shaft is combined with the alternator shaft.
A power plant’s primary benefit is that it does not require any fuel. It needs only the water head that is naturally accessible after the necessary dam has been built.
Advantages of Hydro Power Plant-
No fuel means no fuel costs, no combustion, no flue gas generation, and no atmospheric pollution. The hydro power plant itself is very nice and clean due to the lack of fuel combustion. Besides that, it does not generate any atmospheric pollution. It is also easier than any thermal and nuclear power plant from a constructional point of perspective.
Disadvantages of Hydro Power Plant-
Because of building a massive dam across the flowing river, the building price of a hydro power plant may be greater than that of other standard thermal power plants. In addition to the construction costs, the engineering costs in a hydroelectric power plant are also high. Another drawback of this plant is that according to the load centers it can not be built anywhere.
The transmission of the generated energy to the load centers requires long transmission lines.
The transmission price can therefore be sufficiently high.
However, it is also possible to use the stored water in the dam for irrigation and any other similar purposes. Sometimes it is possible to significantly control occasional floods in the downstream of the river by creating such a dam in the way of the river.
The construction of a hydroelectric power plant requires only six main parts. These are dam, tunnel pressure, surge tank, valve house, penstock, and powerhouse.
The dam is an artificial concrete barrier built across the river path. A huge water reservoir is created by the catchment area behind the dam.
Two kinds of valves are available in the valve house. The first is the primary sluicing valve, while the second is an automatic isolation valve. The sluicing valves regulate the downstream flow of water and automatic isolating valves prevent the flow of water when the electrical load is suddenly thrown off the plant. Automatic isolating valve is a protective valve that does not directly regulate the water flow to the turbine. It only works to safeguard the system from bursting out during an emergency.
The penstock is an appropriate diameter steel pipeline linked between the house of the valve and the powerhouse. The water only flows through this penstock from the upper valve house to the lower powerhouse.
In the powerhouse there are water turbines and alternators to produce and then promote electricity transmission with related transformers and switchgear systems.
We’re lastly coming to the surge tank. The surge tank is also a hydroelectric power plant-related protective accessory. It’s just before the valve house. The tank height must be higher than the water head stored behind the dam in the water reservoir. This is a tank of open top water.
This tank’s aim is to safeguard the penstock from bursting when turbine suddenly refuses to carry water. Turbine doors are controlled by governors at the turbine entry stage. Depending on the electrical charge fluctuation, the governor opens or closes the turbine doors. If the electrical load is suddenly thrown off from plant, the governor closes the doors of the turbine and the penstock blocks water. Sudden water shutdown can cause a serious penstock pipeline burst. By swinging the level water in this tank, the surge tank absorbs this back pressure.
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