To Study About Hydro Power Plant

Hydro Power plant

The purpose of this experiment is to study the constructional details and working principle of hydropower plant.

Principle of Hydro Power Plant:
  • A generating station which utilizes the potential energy of water at a high level for the generation of electrical energy is known as hydro-electric power station. As we know that the power plant is defined as the place where power is generated from a given source, so here the source is hydro that‟s why we called it “hydro power plant”
  • The term “hydro‟ is the Greek word for water and hydro power is the energy contained  in water.
  • Hydro power is considered a renewable energy source.
  • Hydro power transform the potential energy of a mass of water flowing in a river or stream with a certain vertical fall (termed the “head”).
  • The power output from the scheme is proportional to the flow and to the head.
  • The water or hydraulic turbines converts this kinetic and potential energy into mechanical power and is thus a prime mover, which coupled to a generator, produces electrical power. The power plants designed to produce  electric power  from water,  flowing continuously under pressure are known as “hydro-electric power plants”.
Theory

The hydro Power plant plays very important role in development of the country as it provides power at cheapest rate as source of natural energy. About 20% of the total world power  is  generated  by  hydro Power  station.  As  on  the  date  about  23%  of  energy  is contributed by hydro power to India. The main source of hydroelectricity is the water which is  readily  available  in  India.  Hydroelectric  power  defines  the  usage  of  water  resources towards  inflation  free  green  energy  in  the  absence  of  fuel  cost  with  mature  technology characterized  by  highest  prime  moving  efficiency  and  operational  flexibility.  Reservoir hold lots of water which is employed to generate power by means of turbines.

We  start  to  generate  electricity  from  hydro  power  in  1882  when  United  States  (US) establishes a first hydro power station which generate 12.5 kilowatts (KW) of power. The rapid growth of hydro power comes in 1900‟s when hydraulic reaction turbine comes in picture as a result in 1900‟s hydro power plants fulfill the requirement of 40% of total United states‟ electricity.

For  construction  of  hydro  power  plant  first  we choose  the  area  where the  water is sufficient to reserve and no crisis of water and suitable to build a dam. The main function of dam is to stop the flow of water and reserve the water in reservoir. Mainly dam is situated at  a  good  height  to  increase  the  force  of  water.  Reservoir  hold  lots  of  water  which  is employed to generate power by means of turbines. To control the pressure of water means increase  or  decrease  water  pressure  whenever  required,  we  use  a  valve.  After  that  we employ  turbine  and  generator  turbine  is  the  main  stuff,  when  water  comes  through  the pen stock  with  high  kinetic  energy  and  falls  on  turbine  blades,  turbine  rotates  at  high speed.  As  we  know  that  the  turbine  is  an  engine  that  transfers  energy  of  fluid  into mechanical  energy  which  is  coupled  with  generator  converts  mechanical  energy  into electrical energy which we utilized at the  end.

In  hydro  power  plant  we  also  add  switchgears  and  protections  which  control  and protect the whole process Inside the Plant. We use step up transformers to enlarge the level of Voltage (generally 132KV, 220KV, 400KV, and above) as per our requirement. After that  we  transmit  the  electric  power  to  the  load  and  then  we  step  down  the  voltage  for industrial  and  large  consumer  and  then  again  we  step  down  the  voltage  to  distribute electricity at domestic level which we used at home.

This is the whole process of generating electricity by the means of hydro (hydro power plant) and then transmitting and distributing electricity.

In a hydro power plant, the water is collected across the river by constructing a dam. The water from dam is passed through the pipes to turbines. The water coming out of nozzle at high velocity strikes  on the blades mounted  on the wheel (turbine)  where the kinetic energy of water is converted into mechanical energy as it‟s.

For  construction  of  hydro  power  plant  first  we choose  the  area  where  the  water is sufficient to reserve and no crisis of water and suitable to build a dam. The main function of dam is to stop the flow of water and reserve the water in reservoir. Mainly dam is situated at  a  good  height  to  increase  the  force  of  water.  Reservoir  hold  lots  of  water  which  is employed to generate power by means of turbines. Penstock, the pipe which is connected between dam and turbine blades and most important purpose of the penstock is to enlarge the kinetic energy of water that‟s why this pipe is made up of extremely well-buildmaterial which carry on the pressure of water. To control the pressure   of   water   means   increase or decrease water pressure whenever required, we use a valve. the  turbine  is  an  engine  that  transfers  energy  of  fluid   into   mechanical   energy which is coupled with generator converts mechanical energy into electrical energy which we utilized at the  end.

Fig. 1: Principle of Hydroelectric Power plant

Fig.2: System of the Hydro Power plant

Components of hydro-electric power plant

Catchment area

The Catchment  area  of  a  hydro  plant  is  the  whole  area  behind  the  dam,  draining into  a stream or river across which the dam has been built at suitable place.

Reservoir

Whole of water available from the catchment area is collected in the reservoir behind the dam.

Function : To store the Water during rainy season and supply the water during dry season.

Dam

A dam is built across a river.

Function : To increase the height of water level behind it which ultimately increases the reservoir capacity.

Trash Race

Function : To  prevent  the  entry  of  debris  which  might  damage  the  fixed  Blades  and  runner  of turbine or chock up the nozzles of the impulse Turbine.

Fore Bay 

These are a kind of storage tanks which are present at end of the Head race pipe or canal. These are input to the pen stock.

Function : To serve as a regulating reservoir, temporarily storing water When the load on the plant is reduced and provides water for initial Increment of an increasing load while water in the canal is being accelerated.

Surge Tank

Function : It provides better regulation of water in the system during Variable load conditions.

Penstock

Function : To carry water under the pressure from the large reservoir to the turbine. It‟s pipes of large diameters and commonly made of steel through reinforced concrete. These are input to the penstock.

Spillway

Function : To discharge major floods without damage to the dam and same time keeps the reservoir level below predetermined maximum level, therefore it considered safety valve for dam.

Turbine ( Prime Mover )

Function : To convert the kinetic energy of water into mechanical energy to produce electric energy.

Electric Generator 

It is used to produce electricity from turbine mechanical energy. There are various type of generator  used  in  hydro  plant  like  synchronous  generator,  D.C.  generator  and  Induction generator.

Power House

Function : The power house consists of substructure to support the Hydraulic and electric equipment and superstructure to house and protect this equipment.

Draft Tube 

The draft tube is essential part of reaction turbine.

Function : To discharge water from exit of turbine to tail race.

Tail Race

It is a passage for discharging water leaving the turbine or draft tube into the river.

 

Formula For A Hydroelectric Power And Energy & Efficiency

Expressions:

𝒑=𝜸×𝑸×𝑯𝒈  ×𝒆

𝑬=𝜸×𝑸×𝑯𝒈 ×𝒆×∆𝒕

                                        Where,

                                                         P = power (KW)

                                                         E = energy (KWH)

                                                         Q = discharge ( m3 /s)

                                                       𝐻𝑔 = gross head (m)

                                                           e = overall unit efficiency (%)

                                                            e = (ℎ𝑦𝑟𝑙𝑖) ×(𝑟𝑖) ×(𝑔𝑟𝑟)

Where:

Overall efficiency = power available at the shaft / Power available at Water jet

                                 = shaft power / water power

                                 = P / WQH

H – Is the net or efficiency head in meters and Q is the total Discharge in m3/s

 

Specifications:
  • A proven hydro power plant library to be provided, which should comprise of the following component models as a minimum.
  • Reservoir- should be possible to parameterize to any geometrical shape, can be discretized, and wave propagation due to transients should be covered.
  • Head Race Tunnel – should be possible to parameterize to any geometrical shape.
  • A pipeline model using a TLM (transmission line modelling) approximation to wave propagation in pipes, penstocks and general closed condition.
  • Surge Shaft – Should include a surge shaft connected to multiple penstocks.
  • Penstock- Should include    penstocks  supplying  multiple  turbines  connected  in  parallel, elastic &  inelastic water column effects, water hammer, travelling wave effect to be covered.
Experiments

A. Calculation of the Turbine Efficiency

The requirement of the data to calculate turbine efficiency and calculation will be write to the observation table given below:

Measurement No:  Initial time T1 Final time T2
Rotation speed of turbine shaft(rev/s)
Force(N)
Water flow rate(m3/h)
Water inlet pressure(bar)

Calculation: Using the appropriate equations, calculation the overall Efficiency.

B. Change the turbine efficiency with respect to flow rate:

The necessary data for understanding how turbine efficiency alters when the flow rate is varied and calculations will be recorded to the Observation table given below:

Measurement No:             Rate, R1  Rate, R2 Rate, R3
Rotational speed of turbine shaft(rev/s)
Force(N)
Water flow

rate(m3/h)

Water inlet

pressure(bar)

Calculation: Using the appropriate equations, calculate the efficiency of turbine and draw the graph of efficiency versus flow Rate.

C. Calculation of the generator efficiency:

The necessary data for understanding how calculate generator efficiency and calculation will be recorded to the observation table given below:

Measurement No Initial time T1 Initial time T2
Water flow rate(m3/h)
Water inlet pressure(bar)
Power(W)

Calculation: Using the appropriate equation, calculation the efficiency of generator.

 

Quiz

1) Draw general layout mentioning essential components of hydro Power plant.Explain the function of each components.

2) Classify the Hydro-electric power plants according to availability of head, Quantity of water and nature of  load.

3) List the factors affecting selection of site for hydro-electric power plant.

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